隧道硬岩大变形

公路隧道在工程建设中愈发常见。为研究裂隙围岩在开挖扰动作用下的塌方规律，本文以某一公路隧道为工程背景，借助UDEC离散元模拟软件，得到岩体位移、速度、加速度随时间变化的曲线图，模拟开挖扰动下隧道塌方的演变过程，为类似的隧道工程建设和支护提供建议。

为研究地下洞库岩体的破坏特征，开展含孔洞真实砂岩模型双轴压缩试验，同时结合声发射系统从岩石内部分析裂纹的演化过程及破坏前兆信息。试验结果表明，洞口拱脚处由于应力集中最先出现裂纹，裂纹沿着尖端向拱肩发展。洞室内部出现板裂现象，两侧直墙岩体受裂纹切割掉落至拱底。加载前期声发射信号微弱，随着裂纹的萌生及扩展，声发射活动逐渐变得活跃。即将到达隧洞峰值荷载时，声发射信号突然下降进入平静期，达到峰值荷载时声发射特征参数跃升均达到最大值，声发射平静期能够作为岩体破坏的预兆信息。

通过分析隧道侧导坑法施工过程中引起围岩的应力重分布的规律，研究隧道压力拱的动态变化，探究侧导坑法施工对隧道压力拱的影响规律，得出：隧道侧导坑法开挖时，上部压力拱的内外界随导坑宽度的增大而增大，侧向压力拱的内界随侧导坑宽度的增大而减小，侧向压力拱的外界基本保持不变；而侧导坑开挖后，压力拱的分布范围受侧导坑宽度的影响较大，侧导坑宽度对最终压力拱不产生影响。研究成果为隧道施工选择侧导坑法时提供理论基础和方法依据。

本文以探究不同侧压力系数对隧道开挖围岩稳定性的影响规律为研究目标，采用FLAC3D有限差分软件建立直墙半圆拱隧道模型，通过在隧道关键位置处(隧道顶、底、两侧)布置位移监测点，研究不同测出压力系数条件下，隧道开挖后垂直位移、水平位移的变化规律；在总结隧道开挖后塑性区变化规律的基础上，进一步分析侧压力系数对隧道围岩稳定性的影响规律。研究结果表明：在其余条件保持不变情况下，侧压力系数与围岩塑性区、垂直应力、水平应力皆呈现正相关关系，侧压力系数越大、隧道开挖之后围岩越不稳定，且不稳定区域集中在拱顶、拱底与拱肩处。研究成果可为相似地质条件下隧道开挖过程中的围岩支护提供理论依据。

随着我国隧道和地下空间迅速向深部发展，深入认识高应力下洞周围岩力学特性及损伤破裂机制对岩石地下工程施工设计和安全防护具有重要意义。从深埋岩石力学特性、声发射特征及损伤破裂机制等三个方面介绍了高应力下岩石损伤破裂机制研究进展，表明：1) 目前针对不同应力、加卸载速率等条件下的岩石变形、强度和破坏特征研究已相对成熟，但针对多场耦合等复杂环境下岩石力学特性及微细观破裂机制方面的研究还相对较少。2) 利用声发射特征参数变化规律来反演岩石破裂特征及前兆点预测的研究已较为成熟，但针对岩石峰值后残余阶段的声发射特征研究及利用声发射特征参数反演岩石损伤理论的归一化研究尚处于一个不断完善的探索阶段。3) 目前所建立的岩石统计损伤本构模型考虑了岩石材料的各向异性，使模型的计算结果更趋于实际，但大多仍处于理论阶段，有待结合室内或者现场试验验证。

文章深入探讨了隧道岩爆现象，包括其定义、成因、分类以及对隧道工程的影响。首先，分析了岩爆的突发性、不确定性、破坏性等关键特征，讨论了其全球分布和具体案例，如英吉利海峡隧道和青藏铁路隧道的岩爆事件。其次，探讨了岩爆的地质、工程和环境成因，指出了岩石物理性质、地质构造、开挖方法、支护设计和地下水等因素对岩爆的影响。最后，提出了包括设计优化、施工技术改进、支护和加固措施、风险管理以及应急预案在内的综合防治策略，旨在为隧道工程的安全施工和岩爆风险管理提供科学依据和实际指导。

地质力学模型试验技术是一种重要的工程力学分析手段，在隧道工程领域具有广泛的应用价值。本文介绍了地质力学模型试验技术的基本原理和特点，依托工程实例利用相似理论做出相应的模型箱等相关试验材料，阐述了其在隧道工程中的试验系统组成，包括模型箱、加载系统、相似材料、量测系统等。

为了探讨空间上的地层岩性界面对构造裂缝发育的影响，以库车坳陷白垩系和古近系致密砂岩储层为例，结合岩心和野外观察，配合力学实验、应力应变关系推导及破裂准则选取，研究软硬相间岩层在不同受力条件下的变形破坏特征，最终采用弹塑性有限元法模拟三维应力分布和裂缝发育规律。结果表明：砂泥岩组合方式与裂缝类型及发育规律关系密切，岩性界面处裂缝可划分为：界面滑移缝、界面终止缝、界面贯穿缝和界面转换缝四种基本类型；厚层均质砂岩中中尺度共轭缝发育，薄层中层间杂乱缝发育，50 cm以上夹层可挡住大尺度缝的延伸；水平受力条件下，泥质夹层厚度和泥/砂厚比控制着裂缝的发育规律，当泥/砂厚比值位于0.1~0.35时，泥岩内裂缝密度达最高值；围压条件下，随应力的增加裂缝密度迅速增大，在300 MPa时达最大值；同等应力条件下，砂岩层越薄越容易产生裂缝，泥岩厚度和应力强度对砂岩裂缝在泥岩中延伸的长度影响很小，即不管泥岩上下砂岩层的厚度如何，泥岩恰好不被穿透的厚度都为3 m左右。

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The mechanical and deformation behaviors of the surrounding rock play a crucial role in the structural safety and stability of tunnel shafts. During drilling and blasting construction, seepage failure and hard brittleness damage of the surrounding rock occur frequently. However, previous discussions on stress deformation in the surrounding rock did not consider these two factors. This paper adopts the theory of elastoplastic to analyze the effects of seepage and hard brittleness damage on the stress and deformation of the surrounding rock of a tunnel shaft. The seepage effect is equivalent to the volumetric force, and a mechanical model of the surrounding rock considering seepage and hard brittleness damage was established. An elastoplastic analytical formula for surrounding rock was derived, and its rationality was verified through numerical examples. Based on these findings, this study revealed the plastic zone as well as stress and deformation laws governing the behavior of surrounding rock. The results showed that the radius of a plastic zone had a significant increase under high geostress conditions, considering the hard brittleness damage characteristics of the surrounding rock. The radius of the plastic zone increased with an increase in the initial water pressure and pore pressure coefficient, and the radius of the plastic zone increased by 5.5% and 3.8% for each 0.2 MPa increase in initial water pressure and 0.2 increase in pore pressure coefficient, respectively. Comparing the significant effects of various factors on the radius of the plastic zone, the effect of support resistance inhibition was the most significant, the effect of the seepage parameter promotion was the second, and the effect of the hard brittleness index promotion was relatively poor. The hard brittleness index and water pressure parameters were positively correlated with the tangential and radial stresses in the surrounding rock, and the radial stresses were overall smaller than the tangential stresses. The deformation of the surrounding rock was twice as large as the initial one when hard brittleness damage and seepage acted together. These findings can provide a reference for the stability evaluation of the surrounding rock in tunnel shafts.

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In rock engineering, the dynamic loads caused by mechanical action and rock blasting have an extremely significant influence on the stableness of surrounding rock masses. To examine the impact of dynamic load on the mechanical properties and fracturing characteristics of hard rocks as well as the failure responses of underground openings, a number of prismatic samples with holes of different numbers and configurations were prepared for dynamic tests employing an SHPB loading device. The experimental results demonstrate that the order of dynamic compressive strength of each group of samples under the impact nitrogen pressure of 0.45 MPa is: G3 > G2 > G5 > G4 > G7 > G6, and the dynamic deformation process of the samples is parted into three phases: linear elastic deformation, plastic deformation and post-peak deformation. A total of three categories of cracks, i.e., spalling cracks, shear cracks and tensile cracks, occur in the specimens. The failure mode of the samples having one or two holes arranged in a vertical direction is controlled by shear cracks, whilst that of the rest groups of pre-holed specimens belongs to tensile-shear failure. The existence of the fabricated holes in the samples significantly weakens the mechanical properties and affects the fracture evolution characteristics, which rely on the quantity and layout of the cavities in the specimens. The interesting results are also discussed and explained, and could supply some insight in the mechanisms of tunnel surrounding rock failure and rock dynamic hazards such as rock burst.

Aiming at the crucial engineering challenge of the ambiguous excavation deformation mechanism of hard and brittle surrounding rock under high geos-tress conditions, with the right bank diversion tunnel at the dam site of the hydropower station as the research object, the deformation and failure characteristics of the surrounding rock and their formation mechanisms during the layered excavation of the diversion tunnel were investigated. The research findings show: (1) The main factors influencing the deformation of the diversion tunnel’s surrounding rock are the high ground stress environment, the degree of fracture development in the rock mass, and the effectiveness of the support system. (2) Following the excavation of the first layer, extensive shallow damage predominates, with damaged blocks primarily exhibiting sheet-like and plate-like forms. After excavating the second and third layers, there is a significant reduction in confining pressure in this region, leading to a rapid deterioration in the extent of damage. (3) Layered excavation induces ‘time-dependent’ variations in the yield characteristics of the surrounding rock, while simultaneously being influenced by the location and extent of fracture development. The study results are expected to provide a theoretical basis for the excavation of underground caverns under high ground stress.

Based on five different constitutive models, the progressive failure process of deep hard rock was simulated, and the plastic zone, shear strain increment high-value zone, horizontal displacement, and maximum principal stress distribution of surrounding rock were obtained. The calculation results show that the plastic zone of surrounding rock calculated by MCSS and HBSS models is mainly concentrated in the floor and vault of the cavern, and the sidewall is not damaged. There is no shear zone in the surrounding rock, and the magnitude of horizontal displacement is 10-4. In the L-CWFS model, the hysteresis cohesion of friction strengthening is weakened, and the initial friction angle is 0. The calculated plastic zone runs through the surrounding rock, and the whole section is destroyed. The order of magnitude of the horizontal displacement extremum is 10-3. The MC-HB model simulates the spalling failure of the side wall, and the strain localization of the side wall is not obvious, and no shear band is formed inside the surrounding rock deeply. The N-CWFS-TSS model simulates the buckling failure process of the straight wall plate crack. A shear band is formed at the bottom of the straight wall and penetrates into the interior of the surrounding rock. The strain localization is obvious and the order of magnitude of the shear strain increment is 10-2. The calculation results are consistent with the results of laboratory tests and field observations, and the failure mechanism of the compression-shear-tensile-shear composite in the progressive failure process of the surrounding rock is clarified.

To solve the key problems of tunneling and excavation, deformation and rupture of surrounding rocks in TBM tunnel model test research in deep composite stratum was conducted. This research employed a combined strategy of physical model test and numerical simulation for studying the deformation and fracture laws of the surrounding rock in a vertical section of a TBM tunnel in deep composite strata. In this study, the main research results are 1) The “soft and hard unevenness” and “combination effect” of the composite stratum affected the overall bearing capacity of the tunnel resulting in failure at a shallower buried depth or a lower stress concentration factor. 2) When the model was only excavated and unloaded, the plastic zone was basically near the periphery of the tunnel, resulting mainly in shear failure. In the lower layer of the composite stratum tunnel, the plastic zone due to its higher strength parameters was smaller than that in the upper layer. 3) Under the premise of the axial loading and surrounding constraints, the deformation and failure mode of the TBM tunnel in the deep composite strata exhibited “X”-type failure characteristics. The vertical section of the partially excavated rock mass revealed that the rock mass at the top layer of the tunnel caused a sudden and integral shear sliding of the palm face along the oblique direction upward 50°. This research provides significant and important guidelines for solving the problems of safety in TBM tunnel construction in a deep composite stratum.

We develop a novel computational framework based on the particle finite element method for simulating rockburst phenomena, from pre-failure initiation to failure evolution and to post-failure mobilisation and ejection, across spatiotemporal scales in hard rocks. The proposed framework builds upon a rigorously validated and extensively calibrated particle finite element model, distinguished by its unique capability to handle large deformation problems. This framework can simultaneously capture the creep damage mechanism based on a time-dependent strength degradation model and the brittle fracturing process based on a cohesion loss-frictional strengthening model. The post-failure mobilisation is further governed by a frictional weakening formulation to capture the associated stress drop behaviour. We consider the intrinsic material heterogeneity assuming a Weibull distribution of rock mass properties and represent the nearby fault zone as a thin continuum layer with equivalent mechanical properties. We apply the model to investigate the processes and phenomena of deep tunnelling-induced rockbursts under different stress and heterogeneity conditions. Our simulation results, grounded in a thoroughly validated modelling framework, yield insights with important implications for understanding and predicting catastrophic rockbursts during deep tunnel excavation. While further site-specific calibration would be required for practical application, the current framework demonstrates strong potential as a predictive tool for evaluating rockburst hazards in complex geological settings.

With the further implementation and development of the Western Development Strategy, studying the mechanical behavior and deformation characteristics of deep-buried tunnels in layered hard rock under high ground stress conditions holds considerable engineering significance. To study the mechanical properties and long-term deformation and failure characteristics of different bedding stratified rocks, this research employed an MTS815 electro-hydraulic servo rock testing system and a French TOP rheometer. Triaxial compression tests, rheological property tests, and long-term cyclic and unloading tests were conducted on shale samples under varying confining pressures and bedding angles. The results indicate that (1) under triaxial compression, shale demonstrates pronounced anisotropic behavior. When the confining pressure is constant, the peak strength of the rock sample exhibits a “U”-shaped variation with the bedding angle (its minimum value at 60°). For a fixed bedding angle, the peak strength of the rock sample progressively increases as the confining pressure rises. (2) The mode of shale failure varies with the angle: at 0°, shale exhibits conjugate shear failure; at 30°, shear slip failure along the bedding is controlled by the bedding weak plane; at 60° and 90°, failure occurs through the bedding. (3) During the creep process of layered shale, brittle failure characteristics are evident, with microcracks within the sample gradually failing at stress concentration points. The decelerated and stable creep stages are prominent; while the accelerated creep stage is less noticeable, the creep rate increases with increasing stress level. (4) Under low confining pressure, the peak strength during cyclic loading and unloading creep processes is lower than that of conventional triaxial tests when the bedding plane dip angles are 0° and 30°, which is the opposite at 60° and 90°. (5) In the cyclic loading and unloading process, Poisson’s ratio gradually increases, whereas the elastic modulus, shear modulus, and bulk modulus gradually decrease.

Rockbursts are characterized by violent rock fractures and pose a significant threat to hard-rock tunnels, potentially resulting in casualties and damage to excavation spaces. Globally recognized as one of the least understood and most feared challenges in underground excavations, rockbursts are often triggered by dynamic disturbances such as engineering activities or nearby vibrations. This study conceptualizes rockbursts as dynamic buckling or instability issues inherent in rock structures. It specifically investigates the mechanism of tunnel rockbursts induced by ambient blasting. The derivation of the governing equation of motion, which incorporates shear deformation and rotary inertia of the rock column, results in coupled Mathieu equations. By employing the proposed numerical method, the conditions triggering rockburst were established using instability diagrams. The study examines the effects of static components, dynamic loading, and frequency on a tunnel example, revealing that the amplitude and frequency of dynamic disturbances are critical in influencing the occurrence of tunnel rockbursts through perturbation effects and parametric resonance mechanisms. These insights offer valuable understanding into the mechanisms, mitigation, and control of tunnel rockbursts.

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The deterioration of the surrounding rock at the tunnel bottom is a damage mechanics issue that occurs under disturbance load. To investigate the anisotropic characteristics of mechanical behavior and the AE response mechanism of layered sandstone, uniaxial compression tests and acoustic emission (AE) monitoring were conducted. The results show that the layer structure causes remarkable anisotropic characteristics in the wave velocities. The strain characteristics and mechanical parameters of layered sandstone exhibit obvious deterioration effects. The local strain and overall strain show a synergistic feature, with the local strain path being more complex and the deformation response being extremely sensitive. The peak stress and elastic modulus both exhibit V-type distribution rules, slowly decreasing first, then rapidly decreasing, and finally increasing rapidly, with the boundary points of the layer angle being 45° and 67.50°. The peak stress and elastic modulus show a nonlinear exponential correlation with the layer angle, and the sandstone belongs to the intermediate anisotropy level. The rupture pattern shows significant anisotropic characteristics, with the failure modes including tension failure, including tension failure I and tension failure Ⅱ, shear failure, and tension–shear composite failure. The fractal dimension shows a negative correlation with the layer deterioration effect. The AE activity exhibits a phased response characteristic to the aging deformation of layer structure. The more obvious the layer deterioration effect is, the longer the AE delay is. The AE intensity of tensile failure sandstone is generally greater than that of oblique shear failure.

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This paper aims at deriving a closed‐form solution for deep lined tunnels within a saturated anisotropic poro‐elastic medium. The derivation of the solution is carried out with the assumption of plane strain conditions along the tunnel axis, an isotropic elastic liner, a steady‐state flow, and perfect contact between the liner and rock. For this purpose, the complex potential function approach pioneered by Lekhnitskii for the anisotropic elastic body was used to develop the mechanical response of the rock mass. A complex hydraulic potential function is also introduced to solve the steady state fluid flow. Then the well‐known Biot theory is chosen to describe the hydro‐mechanical coupling of the anisotropic saturated rock. The stress and displacement solutions of both the liner and the surrounding rock, considering the tunnel face advance with respect to the considered section, are derived based on the principle of the convergence‐confining method. Comparisons with previous closed‐form solutions for isotropic case and finite element solution for anisotropic case were made to show the accuracy of the current closed form solution. Sensitivity analysis is performed based on this analytical solution to highlight the effect of some rock parameters on the stress and displacement of the liner.

Accurately identifying surrounding rock failure modes and designing matching support systems are critical to the safety of deep-earth and underground space engineering. We develop a graded classification scheme based on the rock strength-to-stress ratio and the Stress Reduction Factor (SRF) to quantify failure types and guide support design. Within the convergence–confinement method (CCM) framework, we establish analytical models for shotcrete, rock bolts, steel arches, and composite support systems, enabling parameterized calculations of stiffness, load-bearing capacity, and equilibrium conditions. We conduct single-factor sensitivity analyses to reveal how the Geological Strength Index (GSI), burial depth (H), and equivalent tunnel radius (R0) govern the evolution of surrounding rock pressure and deformation. We propose targeted reinforcement strategies that address large-deformation and high-stress instabilities in practice by linking observed or predicted failure modes to specific support schemes. A large-deformation case study verifies that the proposed parameterized design method accurately predicts the equilibrium support pressure and radial deformation, and the designed support scheme markedly reduces convergence. Accordingly, this study provides a practical tool for tunnel support parameter design and an analytical platform for safe, reliable, and efficient decision making for initial support.

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Abstract Predicting tunnel crown settlement and convergence remains challenging due to uncertainties unaddressed by traditional methods. This study proposes an interpretable intelligent model to enhance surrounding rock deformation predictions. Six heuristic swarm intelligence optimization algorithms (HSIOAs) are applied to enhance the Deep Belief Network (DBN) model. Six DBN-based models are compared against classical machine learning models using metrics like RMSE, R2, MAE, and VAF. The KOA-DBN achieves the best performance, with R2 = 0.938, RMSE = 0.484 mm, and MAE = 0.381 mm for crown settlement, and R2 = 0.949, RMSE = 0.947 mm, and MAE = 0.767 mm for tunnel convergence. KOA-DBN outperforms hybrid models, improving R2 by 1.1%–4.3% and reducing RMSE by 7.6%–16.3% and MAE by 8.7%–29.5%. Its accelerated convergence boosts computational efficiency, while compatibility with monitoring systems enhances deformation prediction accuracy and safety. SHAP analysis identifies burial depth, lateral pressure coefficient, and support type as key deformation factors. This framework effectively addresses complex tunnel engineering challenges and offers a practical solution for deformation forecasting, with strong potential to support real-time decision-making and enhance safety standards in tunnel construction.

In order to solve the problems of low prediction accuracy and poor generalization ability of the current tunnel surrounding rock deformation, this paper proposes a method based on Bayesian optimization long short-term memory network (LSTM). This method first analyzes the vault settlement Preprocess the original monitoring data of the highway tunnel vault settlement and peripheral convergence, and then construct an initial LSTM model of the highway tunnel vault settlement and peripheral convergence, and use Bayes to optimize the hyperparameters in the model to finally obtain the prediction results.

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The monitoring, analysis and prediction of surrounding rock deformation during underground tunnel construction is the crucial points of NATM construction. The convergence deformation and vault settlement of surrounding rock of underground tunnel comprehensively reflect the dynamic adjustment process of surrounding rock stress and the supporting effect of supporting structure after tunnel excavation. The observed values can serve as the basis for judging the initial supporting stability of surrounding rock and selecting a reasonable time for secondary supporting. In this paper, the grey theory is implemented to establish the prediction model of the convergence deformation and vault settlement of tunnel surrounding rock. According to field monitoring and grey prediction results, the deformation stability of surrounding rock of underground tunnel is analyzed from two aspects of relative displacement and deformation rate, and the secondary support time is reasonably determined. The analysis results can provide reference for the design, construction and monitoring of similar projects.

Relying upon a three-dimensional finite element analysis, this contribution investigates the instantaneous irreversivel response induced by the constitutive behavior of the rock mass in the convergence profile of twin tunnels. At the rock material level, elastoplastic state equations based on a Drucker-Prager yield surface with an associated flow rule are adopted in the modeling. As regards the tunnel support, the formulation accounts for the presence of an elastic shotcrete-like lining. From a computational point of view, the deactivation-activation method is used to simulate the excavation process and the installation of the lining. The accuracy of the finite element predictions is assessed through comparisons with the available analytical solutions formulated in a simplified scenario for the twin tunnel configuration. A parametric study investigates the mutual interaction induced by the proximity of the tunnels.

Large-scale rock burst disasters often occur in high-stress and deep-buried tunnels, due to challenges in accurate forecasting and the lack of clarity regarding the underlying mechanisms largely. This study combined on-site stress drilling tests, coupled finite and discrete element simulations, and theoretical calculations to examine unloading damage, rockburst evolution, and deformation failure of the high-stress and deep-buried Xuefengshan No.1 tunnel. The initial geo-stress characteristics were inversed to explore the unloading damage evolution and failure mechanism. The influences of stress distribution, displacement development, and energy release on the stability and rock burst risk of surrounding rock masses were analyzed. The rock burst risks along this tunnel were assessed by the energy method and stress intensity ratio method comprehensively. The findings revealed that displacement convergence and stress release caused by unloading during tunnel excavation were most prominent at the tunnel invert and the arch waist on both sides. The displacement of the rock mass within the unloading zone exhibited a symmetrical distribution along the tunnel axis, with displacement gradually decreasing radially outward. The deep-buried granite and slate sustained greater damage during the rockburst compared to sandstone. There were approximately 6500 m of the Xuefengshan No.1 tunnel, accounting for 55.7% of its total length, possessing potential rock bursts, predominantly at weak to moderate levels. The likelihood of rock bursts increased with burial depth, with a marked rise in risk when the depth exceeded 300 m. The results of this study could provide valuable insights into the geo-stress characteristics and rockburst risk assessment for high-stress and deep-buried tunnels.

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Rockbolt support is one of the most commonly used reinforcement measures for rock tunnels. It is important to explore the effect of rockbolts on seismic design of tunnel structures, and therefore, a design method is required for the evaluation of such effect, which was, however, still vacant in current studies. In this paper, a novel analytical solution for the seismic response of deep tunnels with rockbolts support subjected to P and SV waves is presented. The rockbolts support region is assumed to be cylindrical and anisotropic based on the equivalent material method, and the ground and liner are considered homogenous, isotropic, and linear elastic. The general solutions for the response of a cylindrical anisotropic layer subjected to arbitrary dynamic loading are derived using generalized power series. The convergence and the linear independence of the solutions are proved. Then, the solutions for displacements and stresses of the tunnel liner are obtained by utilizing these proposed general solutions. The validity of the proposed solution is demonstrated by comparing its results and those from FEM. Parametric analysis is presented with the solution where the influences of the rockbolts length and modulus of the equivalent layer reinforced by the rockbolts support on seismic responses of deep tunnels are investigated.

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This paper summarises key findings from a 39-month study at CSA Mine on factors controlling anisotropic ground behaviour in sub-level open stope (SLOS) access tunnels at depths of 1500 m – 1700 m. The aim was to understand factors controlling high displacement ground behaviour through numerical and empirical back analysis at 45 damage sites over a 39-month period. It was found that excavation orientation, rock mass matrix and foliation strength, and stress path are key parameters influencing tunnel damage and convergence at CSA Mine. Tunnels driven parallel to foliation (i.e., along strike), experienced much higher levels of damage than those driven perpendicular to foliation. Drives at intermediate angles experience varying levels of damage, depending on rock mass strength and stress. The stress path induced by mining was found to significantly affect both the initiation and progression of damage in both tunnels and raises.

Energy dissipation is a fundamental characteristic of rock failure, and energy-based analysis methods have been increasingly applied in various rock engineering contexts. However, comprehensive studies on the complete energy evolution process of surrounding rock failure induced by deep tunnel excavation remain limited. Considering the effects of intermediate principal stress and the dilatancy behavior of plastic surrounding rock, this study derives, validates, and optimizes an elastoplastic analytical method that incorporates the triaxial stress path and nonlinear behavior of surrounding rock. Based on the principle of energy dissipation, a semi-analytical energy solution accounting for longitudinal excavation effects is further established. The energy evolution and damage development within surrounding rock under tunnel excavation are analyzed for rock masses with different properties. Results indicate that under high in-situ stress conditions, tunnel excavation in elastic-brittle hard rock triggers a rapid surge in the damage variable beyond 100% once the energy storage limit is surpassed, causing brittle failure and sudden energy release toward the cavity, with a fully damaged zone swiftly forming along the longitudinal direction as the excavation face progresses. In contrast, soft rock tunnels display a more gradual damage progression, where the maximum damage variable often remains below 100%, and energy is primarily dissipated through crack propagation and extrusion deformation, leading to a broader range of energy dissipation and significant macro-level deformation, despite a lower longitudinal energy evolution rate. In practical engineering, energy-based analysis proves valuable for developing early warning systems and designing tailored measures to address diverse geotechnical hazards.

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In tunneling through hard rock under high geostress, sudden stress release near the excavation face can lead to collapse or rockburst. Traditional uniaxial and triaxial tests do not accurately simulate the unloading conditions near the excavation face. This paper employs true triaxial unloading tests across various stress paths to study the stress-strain behavior and failure characteristics of rocks. The results show that specimens primarily fail due to strong dilatancy along the unloading surface, with combined shear, tension, and splitting failure modes. Increased axial pressure leads to brittle shear and splitting failure in the rock's center, while decreased axial pressure results in tensile plate fracture near the unloading surface. Additionally, three classic rock failure criteria are discussed, with the Mogi-Coulomb criterion showing the best alignment with strength data during unloading in true triaxial tests.

Overcoming the brittle cracking and the corresponding hard rock has become the key bottleneck challenge in the excavation of underground engineering with high geostress. To further understand the onsite cracking’s characteristics and the basic mechanism of hard rock, we carried out a detailed field monitoring action for basalt breaking behaviors in a large underground powerhouse by in situ investigation, digital borehole camera, multi-point deformation measurement, and real-time micro-seismic monitoring. On the basis of our observations, the inner cracking performances of surrounding rock embodied as discontinuous appearance and open of cracks during excavation, and these fractures were often parallel to the outline of the cavern and extended to the inner side because of the subsequent excavation disturbance. Corresponding numerical simulation indicated that the redistribution of rock stress induced local stress concentration and would result in the splitting break of basalt. Field complicated proof indicated that this stress-induced cracking of basalt belonged to the tensile break, and the macroscopic deformation of the surrounding was the result of the accumulation of abundant open deformation of discontinued cracks. This observed achievement can enrich our understanding of the cracking mechanism of hard rock and provide some key cures for optimization design for underground engineering construction under high geostress conditions.

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With the remarkable advancements in Artificial Intelligence (AI) and Machine Learning (ML) technologies across various fields, these tools offer innovative directions for long-standing, experience-based designs in tunnel and underground construction. Especially in the context of vulnerable rock tunnels under high geostress conditions, these technologies have opened up new avenues for research. In such settings, primary support structures frequently experience large-scale deformation due to rock squeezing, subsequently leading to structural failure. To address this issue, we introduce a novel passive deformation node based on the concept of energy release.Initially, we conducted laboratory tests to investigate the mechanical behavior of this new node. A series of rigorous tests were performed to understand its performance under various conditions. Following the lab experiments, field trials were carried out to validate the mechanical properties of this novel node.Ultimately, we employed the PSO-SVM (Particle Swarm Optimization-Support Vector Machine) algorithm to ascertain the data stability of the passive deformation node. The results were then integrated into the tunnel support design, providing further refinement to the support structures and construction plans

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To improve the understanding of failure mechanisms and behaviour of hard rock tunnel linings, local load conditions were experimentally simulated and monitored using a comprehensive set of sensors and imaging techniques. The data includes measurements from distributed optical fiber sensors (DOFS), high-resolution cameras, load cells, pressure cells and LVDTs. Two types of loads were examined: rock block load and bond loss combined with a distributed load over the area of lost bond. The experiments replicated these conditions and were conducted in a laboratory setting where the shotcrete and substrate rock were substituted by cast fiber reinforced concrete (FRC) and cast concrete, respectively. To facilitate the loads, concrete cones were cast into the substrate concrete and pushed through the FRC top layer with a hydraulic jack to mimic rock block loads. To simulate the bond loss and the associated distributed load, lifting bags were installed and inflated between the FRC layer and substrate cast concrete. All specimens were monitored using DOFS embedded in two perpendicular directions and in two layers in the top FRC layer. In addition, the hydraulic jack was instrumented with LVDTs and load cells to measure displacement and load, and the pressure in the lifting bags was monitored using a pressure cell. Two cameras continuously photographed the top surface of the FRC layer, which had been painted with a speckle pattern, during the testing and the pictures can be used for digital image correlation (DIC). Lastly, each specimen was scanned with a 3D scanner prior to and after testing of the specimen.

Considering the effect of surrounding rock on lining in the design of tunnel lining within fractured rock masses is challenging, particularly in accurately predicting the reserved deformation of the tunnel. This study bases a rock mass classification method and the established Hoek–Brown (H-B) strength criterion to assess the deformation characteristics of the surrounding rock. It establishes a more scientifically rigorous theoretical calculation method for the reserved deformation of tunnel linings that accounts for the rock–lining interaction. An optimization design approach for the lining structure, based on the synergistic effect and considering the stress safety of the concrete lining and the rock’s displacement release rate, is proposed. Case analysis is utilized to validate the safety of the lining design in the study section through computational verification. The recommended optimized lining parameters are identified: the support time is initiated when the tunnel wall’s surrounding rock deforms by 9 mm, and the lining thickness is optimized to 47 cm, which is approximately 36.5% less than the pre-optimization thickness. This precise optimization of support timing and lining thickness enhances both the safety and economic efficiency of the Wufengshan Tunnel. The method allows for the calculation of the optimal combination of support time and lining thickness tailored to different surrounding rock conditions, offering significant reference value for tunnel lining optimization.

Tunnels excavated in a combination of hard and soft rock strata with high ground stress are prone to large deformations, collapse, and other disasters. The Yongfeng Tunnel, a reconstruction and expansion of the G544 line, suffered severe high ground stress from plate compression. This paper studied the surrounding rock pressure and supporting structure stress characteristics of tunnels with a combination of hard and soft rock strata with high ground stress by using earth pressure cells, surface strain gauges, and embedded strain gauges to test all stress related to the surrounding rock, primary support, and secondary lining. It was found that the contact pressure (P1) between the initial support and the surrounding rock and the contact pressure (P2) between the initial support of the leading tunnel were distributed in the direction of vertical stratification, while the contact pressures (P1 and P2) of the lagging tunnel were different due to the excavation unloading of the leading tunnel. The maximum stress positions of the initial support of the leading tunnel and the lagging tunnel were located in the left arch waist and the vault, respectively. However, the maximum stress position of the secondary lining was generally located on the side wall. The research results presented herein can guide future tunnel construction projects.

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Existing research on layout parameters of compressed air energy storage (CAES) cavern groups in hard rock has indicated that the key influential factors for group stability include buried depth, diameter, and cavern spacing. Among these, in contrasting to other factors, the research on cavern spacing is limited. This paper focuses on the issue of safe spacing and proposes a numerical method to determine it. By establishing a series of finite element models, the stress state of surrounding rock, changes in shape, equivalent plastic strain of plastic zone, and cavern wall deformation under different spacing have been studied. When a group of air storage caverns in rows is subjected to high internal pressure, for a small spacing, the plastic zone of the surrounding rock between two caverns is connected. Here, the size of the plastic zone, equivalent plastic strain value, and deformation of the cavern wall are relatively large, making the surrounding rock highly susceptible to damage. As the spacing increases, the horizontal width of the plastic zone, the maximum equivalent plastic strain value, the displacement changes of the cavern wall remain stable. This spacing is virtually the same as that when the plastic zone of the surrounding rock is no longer connected and can be selected as a safe spacing. This study explores the design of cavern safe spacing of underground CAES cavern groups and discusses several influencing factors, which can provide references for follow-up energy storage engineering and research.

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To study the stress distribution characteristics of surrounding rock and the spalling mechanism of deep hard rock tunnels with different arch heights, the complex variable function and angle-preserving transformation method in elasticity theory were applied to the analytic solution of tangential stress distribution of arch tunnels during stress adjustment. In addition, true triaxial tests were conducted on granite cube specimens (100 mm × 100 mm × 100 mm) containing holes with three arch heights (including the 25 mm semi-circular arch, 16.7 mm three-centered arch, 12.5 mm three-centered arch) to simulate the spalling process under different initial ground stresses. The stress distribution solution and experimental results show that the initial failure stress of arch holes is 0.39–0.48 times the uniaxial compressive strength (UCS) of the rock. The initial failure location occurs at the arch foot, where tangential stress maximizes. When the lateral pressure coefficient is in the range of 0.38–0.50, the tangential stress is 3.2–3.5 times the UCS. The rock debris of the hole wall are in thin flake shapes. Symmetrical V-shaped or curved failure zones occurred on hole sidewalls. The stress distribution resolution of the surrounding rock of tunnels with different arch heights shows that with the increasing burial depth, the bearing performance of the semi-circular arch tunnel is optimal. In addition, the maximum tangential stress increases as the height of the arch decreases or the lateral stress increases, making it easier for the initial failure to occur at the foot of the arch.

Columnar jointed rock mass (CJRM) formed by intact rock divided by special symmetrical columnar joints is a special type of rock with poor mechanical properties, strong anisotropy, and weak self-supporting ability, severely affecting the excavation safety and stability of underground tunnels. In this study, taking the Baihetan hydropower station as the engineering background, CJRM geological numerical models with different dip angles that combined well with the natural CJRM were generated based on the geological statistical parameters of the engineering site and were verified to have high rationality and accuracy. Tunnel excavation and overloading tests were carried out on these numerical models, and the results showed that the stress and displacement distributions after excavation exhibited strong anisotropic characteristics under different dip angles, and the positions where engineering safety problems are most likely to occur are the side walls, which are prone to stress-structure-controlled failure mode. The self-supporting ability at different dip angles after excavation from weak to strong are 45°, 60°, 75°, 90°, 30°, 0°, and 15°. The safety factors assessed by overloading for CJRM with dip angles of 0–90° degrees were 2.5, 2.6, 2.6, 1.8, 2.1, and 2.2, respectively, providing a valuable reference for the construction safety and support measures of CJRM excavation.

The rock burst causes a significant threat to the construction of the deep-buried tunnel, and the displacement and fracture evolution characteristics of surrounding rock are investigated during the rock burst. First, the full-time numerical simulation of the rock burst is conducted. Then, the displacement evolution characteristic of the rock is analyzed. Finally, the fracture evolution characteristic of the rock is analyzed. The results indicate that more and more surrounding rock near the left straight-wall segment undergoes fracture and movement with the increase of time, and the rock that heaps up in the tunnel mainly comes from the middle-upper part. With the increase of time, the volume V r of rock moving into the tunnel and the fracture ratio α keep increasing, while the growth trends of V r and α decay. The fracture degree of rock near the left straight-wall segment is the most severe, and the fracture area gradually expands with the increase of time.

Double-arch tunnels in inclined layered jointed rock masses face risks of lining cracking and collapse under bedding-inclined asymmetric stress (BIAS); however, related studies remain limited. Based on a case study of an expressway tunnel case in Zhejiang Province, a three-dimensional discrete element model of a double-arch tunnel was developed using Three-Dimensional Distinct Element Code (3DEC) (version 7.0, Itasca Consulting Group, Inc., Minneapolis, MN, USA). The impacts of joint dip angle (0–90°) and spacing (0.5–6.5 m) on deformation, BIAS evolution, and middle partition wall stability were analyzed. Key findings reveal that joint presence significantly amplifies surrounding rock deformation, with pronounced displacement increases observed on the counter-dip side. The BIAS intensity follows a unimodal distribution with joint dip angles, peaking within the 30–60° range. Increasing joint spacing reduces BIAS effects, with a 57.1% decrease in asymmetric deformation observed when spacing increases from 0.5 m to 6.5 m. The implementation of dip-side pilot excavation with the main tunnel full-face method, combined with an optimized support strategy (installing dip-side bolts perpendicular to joints and extending counter-dip side bolt lengths from 4 m to 6 m), achieved a near-unity stress ratio between tunnel sides under equivalent overburden depths compared to conventional methods. These findings offer theoretical and technical insights for optimizing excavation and reinforcement in similar tunnel engineering contexts.

In the deep and large vertical shaft excavation project, the composite stratum poses a great challenge to the stability of the vertical shaft surrounding rock, especially the upper soft and lower hard stratum. In this paper, a tunnel ventilation shaft is taken as the engineering background, and ABAQUS finite element software is used to establish a three-dimensional numerical model of the deep and large shaft crossing the upper soft and lower hard rock layers, and analyze the radial displacement and stress evolution characteristics of the surrounding rock. Subsequently, the effects of soft and hard rock stiffness ratios and construction stages on the stability of the surrounding rock were investigated by parametric analysis. The results show that the radial displacement and stress of the surrounding rock in homogeneous rock layers increase linearly with depth. However, the radial displacement and stress in the surrounding rock near the soft–hard rock interface decrease sharply with depth. In contrast, the influence of the soft and hard rock interface on the stability of the surrounding rock was most significant during the reverse and forward drilling stages. As the difference between soft and hard rock stiffness increases, the displacement attenuation near the soft and hard rock interface is more significant, and the threat to the stability of the surrounding rock is greater. These findings can provide a reference for deformation control and support optimization of deep and large vertical shafts under complex geological conditions.

One of the interesting features with the ellipsoidal models of anisotropy presented in this paper is their acceptance of analytical solutions for some of the basic elasticity problems. It was shown by Pouya (2000) and Pouya and Zaoui (2006) that many closed-form solutions for basic problems involving linear isotropic materials could be extended by linear transformation to cover a variety of "ellipsoidal" materials. This paper will describe two main varieties of ellipsoidal elastic models and show how well they fit the in situ data for sedimentary rocks; numerical homogenization results for several varieties of fractured rock masses will also be provided.

Temperature increase in saturated porous materials under undrained conditions leads to thermal pressurization of the pore fluid due to the discrepancy between the thermal expansion coefficients of the pore fluid and of the solid matrix. This increase in the pore fluid pressure induces a reduction of the effective mean stress and can lead to shear failure or hydraulic fracturing. The equations governing the phenomenon of thermal pressurization are presented and this phenomenon is studied experimentally for a saturated granular rock in an undrained heating test under constant isotropic stress. Careful analysis of the effect of mechanical and thermal deformation of the drainage and pressure measurement system is performed and a correction of the measured pore pressure is introduced. The test results are modelled using a non-linear thermo-poro-elastic constitutive model of the granular rock with emphasis on the stress-dependent character of the rock compressibility. The effects of stress and temperature on thermal pressurization observed in the tests are correctly reproduced by the model.

Geometry of the rock joint is a governing factor for joint mechanical and hydraulic behavior. A new method of evaluating aperture distribution based on measurement of joint surfaces and three dimensional characteristics of each surface is developed. Artificial joint of granite surfaces are measured,processed, analyzed and three dimensional approaches are carried out for surface characterization. Parameters such as asperity's heights, slope angles, and aspects distribution at micro scale,local concentration of elements and their spatial localization at local scale are determined by Geographic Information System (GIS). Changes of aperture distribution at different normal stresses and various shear displacements are visualized and interpreted. Increasing normal load causes negative changes in aperture frequency distribution which indicates high joint matching. However, increasing shear displacement causes a rapid increase in the aperture and positive changes in the aperture frequency distribution which could be due to unmatching, surface anisotropy and spatial localization of contact points with proceeding shear.

The drilling of geothermal energy, CO2 sequestration, and wastewater injection all involve the pressurized flow of fluids through porous rock, which can cause deformation and fracture of the material. Despite the widespread use of these industrial methods, there is a lack of experimental data on the connection between the pore pressure rise, the deformation and permeability changes in real rock. In order to address this gap in the literature, this study developed an artificial rock material that can be deformed and fractured at low pressures. By controlling the porosity, permeability, and strength of the material during the sintering process, it is possible to mimic various types of rock. The artificial rock was designed to accommodate radial flow and deformation, allowing for the tracking of deformation by monitoring the flux and driving pressure and thus calculating the permeability changes under various pressure conditions. The study was able to examine the impact of both ductile and brittle deformation on the permeability during pressurized flow, which were captured by two models that were adjusted to this scenario. This study provides a link between pressurized flow, rock formation permeability and ductile to brittle deformation, that can constrain risk assessment to geothermal energy and CO2

Rock geophysical properties are widely reported to exhibit non-linear behaviours under low-stress conditions (below 10-20 MPa) before transitioning to the linear elastic stage, primarily due to the closure of microcracks and grain interfaces. Image-based modelling of rock deformation struggles to effectively characterise the microcrack closure effect because of the partial-volume effect, where image voxels are larger than microcracks and contain both pore and solid phases. This study presents a novel method to simulate non-linear rock deformation under elevated stress conditions. The method reconstructs digital rock models by treating partial-volume voxels as transitional phases that incorporate microcracks. By assigning intermediate elastic moduli and assuming that the pore portion within each partial-volume voxel deforms before the remaining solid content, the method employs the finite element method to simulate rock deformation and calculate the porosity of the deformed model. The method is tested on two Bentheimer sandstone models, and the results demonstrate its ability to predict the non-linear changes in porosity and elastic properties as the effective stress increases. This work provides a new pathway for image-based modelling of non-linear rock deformation considering the microcrack closure effect, offering valuable insights into the complex mechanical behaviour of rocks under confinement.

This paper presents a deep learning strategy to simultaneously solve Partial Differential Equations (PDEs) and back-calculate their parameters in the context of deep tunnel excavation. A Physics-Informed Neural Network (PINN) model is trained with synthetic data that emulates in situ displacement measurements in the host rock and at the cavity wall, obtained from extensometers and convergence monitoring. As acquiring field observations can be costly, a sequential training approach based on active learning is implemented to determine the most informative locations for new sensors. In particular, Monte Carlo dropout is used to quantify epistemic uncertainty and query measurements in regions where the model is least confident. This approach reduces the amount of required field data and optimizes sensor placement. The PINN is tested to reconstruct the displacement field around a deep tunnel of circular section excavated in transversely isotropic elastic rock and to determine rock constitutive and stress-field parameters. Results demonstrate excellent performance on small, scattered, and noisy datasets, achieving high precision for the Young's moduli, shear modulus, horizontal-to-vertical far-field stress ratio, and the orientation of the bedding planes. The proposed framework shall ultimately support decision-making for optimal subsurface monitoring and for adaptive tunnel design and control.

A better understanding and anticipation of natural processes such as landsliding or seismic fault activity requires detailed theoretical and experimental analysis of rock mechanics and geomaterial dynamics. These last decades, considerable progress has been made towards understanding deformation and fracture process in laboratory experiment on granular rock materials, as the well-known shear banding experiment. One of the reasons for this progress is the continuous improvement in the instrumental techniques of observation. But the lack of real time methods does not allow the detection of indicators of the upcoming fracture process and thus to anticipate the phenomenon. Here, we have performed uniaxial compression experiments to analyse the response of a granular rock material sample to different shocks. We use a novel interferometric laser sensor based on the nonlinear self-mixing interferometry technique to observe in real time the deformations of the sample and assess its usefulness as a diagnostic tool for the analysis of geomaterial dynamics. Due to the high spatial and temporal resolution of this approach, we observe both vibrations processes in response to a dynamic loading and the onset of failure. The latter is preceded by a continuous variation of vibration period of the material. After several shocks, the material response is no longer reversible and we detect a progressive accumulation of irreversible deformation leading to the fracture process. We demonstrate that material failure is anticipated by the critical slowing down of the surface vibrational motion, which may therefore be envisioned as an early warning signal or predictor to the macroscopic failure of the sample. The nonlinear self-mixing interferometry technique is readily extensible to fault propagation measurements. As such, it opens a new window of observation for the study of geomaterial deformation and failure.

The initiation and development of fractures in rocks is the key part of many problems from academic to industrial, such as faulting, folding, rock mass engineering, reservoir characterization, etc. Conventional ways of evaluating the fracture historical deformations depend on the geologists' visual interpretation of indicating structures such as fault striations, fault steps, plumose structures, etc. on the fracture surface produced by previous deformations, and hence suffer from problems like subjectivity and the absence of obvious indicating structures. In this study, we propose a quantitative method to derive historical shear deformations of rock fractures from digital outcrop models (DOMs) based on the analysis of effects of fault striations and fault steps on the shear strength parameter of the fracture surface. A theoretical model that combines effects of fault striations, fault steps and isotropic base shear strength is fitted to the shear strength parameter. The amount of fault striations and fault steps and their occurrences are estimated, and the historical shear deformations can be inferred. The validity and the effectiveness of the proposed method was proved by testing it on a constructed fracture surface with idealized striations and a fracture surface with clear fault steps. The application of this method on an example outcrop shows an intuitive idea of how the rock mass was deformed and that the distribution, occurrence and mode of new fractures are strictly controlled by preexisting fractures, and hence emphasizes the importance of preexisting fractures in modeling the development of fracture systems.

Systematic numerical simulations of model dense granular materials in monotonous, quasistatic deformation reveal the existence of two different régimes. In the first one, the macroscopic strains stem from the deformation of contacts. The motion can be calculated by purely static means, without inertia, stress controlled or strain rate controlled simulations yield identical smooth rheological curves for a same sample. In the second régime, strains are essentially due to instabilities of the contact network, the approach to the limits of large samples and of small strain rates is considerably slower and the material is more sensitive to perturbations. These results are discussed and related to experiments : measurements of elastic moduli with very small strain increments, and slow deformation (creep) under constant stress.

Inverse problems are ubiquitous in nature, arising in almost all areas of science and engineering ranging from geophysics and climate science to astrophysics and biomechanics. One of the central challenges in solving inverse problems is tackling their ill-posed nature. Bayesian inference provides a principled approach for overcoming this by formulating the inverse problem into a statistical framework. However, it is challenging to apply when inferring fields that have discrete representations of large dimensions (the so-called "curse of dimensionality") and/or when prior information is available only in the form of previously acquired solutions. In this work, we present a novel method for efficient and accurate Bayesian inversion using deep generative models. Specifically, we demonstrate how using the approximate distribution learned by a Generative Adversarial Network (GAN) as a prior in a Bayesian update and reformulating the resulting inference problem in the low-dimensional latent space of the GAN, enables the efficient solution of large-scale Bayesian inverse problems. Our statistical framework preserves the underlying physics and is demonstrated to yield accurate results with reliable uncertainty estimates, even in the absence of information about underlying noise model, which is a significant challenge with many existing methods. We demonstrate the effectiveness of proposed method on a variety of inverse problems which include both synthetic as well as experimentally observed data.

A coupled mech-hydro-chemical model for rock geometry alteration of fractures under water-rock interaction (WRI) and geostress is developed. Processes including WRI, asperity deformation, mineral chemical dissolution and pressure dissolution etc., are taken into account. A feature of this model lies in its approximate linearization to the non-linear pressure dissolution process, which makes this model compatible with existing numerical solute transport models. Case study shows that although usually only a thin layer of rock surface is invaded by WRI, the mechanical weakening of this thin layer tend to induce significant increase in rock surface deformation. Thus, the distributed flow field, mineral dissolution rates, and surface alteration increments etc., are all affected. This indicates that when fracture flow related issues are concerned, we should focus on the top thin layer of rock surface rather than the matrix. Results also show that fluid flow enhances the dissolution of rocks and development of flowing channels; however, at places where stress induces high pressure-dissolution but fluid flows slowly, minerals precipitate and fill up fracture voids. This suggests the hydraulic condition plays a key role in the development of fracture flow channels and the evolution of fracture geometry.

Aiming at the unclear bearing mechanism of the single-layer lining structure of high-performance fiber shotcrete under layered construction in the hard rock section of a highway tunnel, this paper studies the effect of different thickness ratios under layered construction on the flexural performance of the single-layer lining structure. Six types of thickness ratio specimens were subjected to a four-point bending test. The tests employed 3D digital image correlation technology to record and analyze the deformation and failure process of the specimens, and the calculation method of single-layer lining flexural stiffness was modified. The results indicate that the flexural ultimate load of the specimens is achieved at a thickness ratio of 2, which is 20.9% higher compared to a thickness ratio of 0. Layered construction affects the failure mode of the specimens. All specimens exhibit mixed-mode failure. However, with the increase in the thickness ratio, the percentage of flexural failure cracks gradually increases. Under layered construction, the reduction in the effective bending stiffness of fiber shotcrete beams becomes more pronounced as the thickness ratio increases. Based on these findings, the interface influence factor is proposed, and the flexural stiffness is corrected using composite beam theory.

: This study aims to determine the rational construction safety step distance for hard rock tunnels, with the goal of effectively organizing the implementation of various construction processes to meet the requirements of rapid construction in hard rock tunnels. The FLAC3D finite difference software was utilized to establish a three-dimensional model based on the tunnel's cross-sectional form, excavation method, and support parameters, followed by numerical simulation analysis. The deformation patterns of the tunnel surrounding rock and the stress characteristics of the support structure under different construction step distances for II and III grade surrounding rocks were analyzed, and the stability of the tunnel surrounding rock and support structure was investigated. The results indicate that: 1) Under different rock grade conditions, as the tunnel construction step distance increases, the deformation of the tunnel surrounding rock and the stress on the initial support structure both show varying degrees of increase; 2) Considering the actual operation tool configuration and operational space requirements at the construction site of the Ma Bai Shan Tunnel, the bottom plate step distance for II and III grade surrounding rocks is adjusted to 300m, and the secondary lining step distance is adjusted to 400m, achieving the goal of rapid construction in hard rock tunnels while ensuring safety.

In view of the problem of the plastic state of the surrounding rock of loess high-speed railway tunnels changing from hard plastic to soft-plastic, even in a flow-plastic state with increasing moisture content, and appearing collapse and large deformation of support structure, it is put forward to use advanced pipe-roof support. Numerical simulation and site monitoring and measurement are adopted to analyze the tunnel surrounding rock deformation characteristics when different soft-plastic layer thicknesses (1 m, 3 m, 5 m) distributing on tunnel arc, sidewall and invert, and the control effect of advanced pipe-roof support to tunnel construction deformation. Results show: ① The spatial distribution of soft-plastic loess layer has a much greater impact on deformation than its thickness. Vertical and horizontal displacements of the tunnel surrounding rock appear three stages: rapid deformation during the initial stage of excavation, continuous slow deformation and tending towards stable convergence deformation. ② Compared to the situation of no pipe–roof, implement of advance pipe-roof support can significantly improve the control effect of vertical and horizontal displacements of the tunnel surrounding rock. ③ The tunnel surrounding rock deformation characteristics show: it is crucial to control the deformation of surrounding rock from the initial excavation stage to the primary support and sealing before forming a ring. The use of advanced pipe-roof support has a significant effect on controlling deformation during the construction of soft-plastic loess high-speed railway tunnels.

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To investigate the soil displacement rule caused by shield tunneling in soil–rock composite strata, the convergence mode of the shield excavation surface was analyzed. The research accounts for the variations in the slopes of the tunnel and the rock–soil interface along the excavation direction. Based on the stochastic medium theory, the calculation formula of soil displacement under different depths is derived. Surface subsidence was computed and evaluated using three engineering case studies. The results show that the calculated surface subsidence curves exhibit strong symmetry and are similar to the distribution pattern of the measured data. When tunneling through composite strata, the segments are prone to an upward floating motion, leading to a convergence pattern in the cross-section that tends toward a non-equal radial convergence mode with top tangency. Within the same project context, the grouting filling rate (δ) diminishes as the hard rock ratio (B) increases, exhibiting an approximate linear correlation. An increase in the hard rock ratio results in reduced values for lateral and longitudinal subsidence, the width of the lateral subsidence trough, and the main impact zone of the shield tunneling operations.

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When the highway tunnel crosses the soft rock, the primary support structure often fails and damages because it cannot withstand the excessive surrounding rock pressure. For the Magu tunnel in Yunnan Province, which is in the upper hard and lower soft stratum, the surrounding rock deformation is large, and the primary support structure occurs spray concrete cracking, steel arch frame twisting deformation. According to the convergence constraint curve, this paper proposes to adopt the primary support optimization design scheme of "shortening the bench length + optimizing the length and arrangement of anchor rods". According to the numerical simulation results of FLAC3D, the important indexes such as deformation convergence, surrounding rock stress, anchor axial force and thickness of plastic zone in different excavation support conditions are analyzed. The conclusions are as follows: 1. The soft rock at the foot of the benches does not provide sufficient support resistance, resulting in large settlement and convergence deformation that can cause the primary support structure to fail and become damaged. 2. The length of the middle bench and the primary support strength and stiffness contribute most to the deformation. 3. The deformation control effect of the short anchor rods on the surrounding rock is relatively weak. Increasing the length of anchor can better play the role of anchor suspension enhancement and give full play to the surrounding rock's own bearing capacity. Finally, the deformation of the tunnel is under control after adopting the optimized primary support structure, which ensures the smooth construction.

As the penetration of intermittent renewable energy sources increases, compressed air energy storage (CAES) in subsurface caverns has gained attention for its scalability, cost-effectiveness, and long operational lifespan. In regions lacking suitable salt formations, hard rock caverns provide a viable alternative due to their widespread availability and geological stability. This study develops and evaluates two representative cavern configurations—tunnel-type and tank-type—using finite element models based on typical geological profiles. A four-stage simulation framework was employed to assess the mechanical response of the surrounding rock and lining structures under varying internal gas pressures ranging from 10 MPa to 20 MPa. Sensitivity analyses revealed a linear relationship between internal pressure and deformation, with maximum displacements remaining within acceptable millimeter-scale limits. No plastic deformation or structural failure was observed in either the surrounding rock mass or the reinforced concrete lining, indicating sufficient mechanical resilience. Additionally, a limit equilibrium model based on the Mohr-Coulomb strength criterion was developed to evaluate the uplift stability of overlying rock layers. Simulation results for cavern diameters of 12 m and 15 m at a burial depth of 120 m confirm structural safety under a maximum operating pressure of 13.3 MPa. The findings support the suitability of smaller-diameter (φ12 m) tunnel-type caverns for high-pressure CAES applications in hard rock formations, offering an optimal balance between stability, constructability, and storage capacity. The proposed analysis framework provides a robust methodological reference for future underground gas storage design in complex geological settings.

The tunnel face stability in composite strata, commonly referred to as the soft upper and hard lower condition, is a critical challenge in tunnel construction. The soft–hard ratio (SA) strongly influences the limit support pressure as well as the failure mechanism experienced by a tunnel face. This study focused on the Xingye Tunnel project in the Xiangzhou District of Zhuhai City. By conducting numerical simulations, the impact of different SAs on the limit support pressure was investigated. Furthermore, a limit equilibrium model was established on the basis of the analysis of the results of numerical simulation. The findings were then compared and analyzed alongside those of relevant theoretical models. In the event of tunnel face instability of composite strata, the deformation tends to be concentrated mainly in the soft soil layer, with less noticeable deformation in the hard rock layer. The investigation of different SAs revealed a linear decrease in the limit support pressure ratio of the tunnel face in composite strata as SA decreases. The self-stability of the tunnel face was observed when SA ≤ 0.125. Moreover, the limit support pressure ratio predicted by the truncated log-spiral model (TLSM) exhibited a higher degree of agreement with the results of numerical simulation than those of other relevant models. The superiority of TLSM was mainly demonstrated in the range of SA = 0.25 to 1.0.

Considering the large-span underground excavation subway station of Qingdao Metro Line 6 of China for analysis, it is necessary to optimize the traditional support system by investigating relevant codes and other tunnel projects. Based on the active support concept, a high prestressed rock bolt support system is proposed, and the optimization direction is defined to apply a high prestress force to rock bolts, increasing the appropriate spacing between supporting arches and strengthening support at key parts such as the large arch foot area, sidewalls and junctions. Numerical calculations and field monitoring are performed to analyze and evaluate the new support system. Numerical simulation results show that the new support system can effectively improve the stress state of the surrounding rock; the tensile stress area markedly decreases in size or disappears; and the plastic area also decreases in size. Field monitoring results show that the settlement of the arch crown is concentrated at 2–5 mm and the deformation rates are less than 0.5 mm/day. The supporting arches, shotcrete and rock bolts are all less than the yield strength and a high safety reserve. These results verify the safety and rationality of the proposed support system, which can be used as a reference for similar projects.

Tunnel-type anchorage are increasingly used in the construction of long-span suspension bridges. Numerical methods are a major means to study their bearing characteristics and failure modes. The current mainstream research method is still based on continuum mechanics, which cannot simulate the whole failure evolution process of tunnel-type anchorage-surrounding rock system. Therefore, discontinuous deformation analysis method based on discontinuous medium mechanics was used to carry out related research, comprehensively considering the influence of different rock mass quality and faults. The results show that: 1) In the case of soft rock and hard rock, the bearing capacity of the tunnel-type anchorage increases with the increase of the clamping angle, and the change in hard rock is more obvious. 2) Under the condition of soft rock, the envelope area of resistance body increases linearly with the increase of clamping angle. Because of gravity, the envelope area of the resistance body on the lower side of the tunnel-type anchorage is larger than that on the upper side. Under the four clamping angles of 2°, 4°, 6° and 8°, the envelope curves on the upper and lower sides of the tunnel-type anchorage are parallel to each other on their own sides. 3) Compared with the soft rock, the envelope areas of hard rock under the above four clamping angles are significantly increased, and the growth multiple is between 0.44 and 0.87. But in this case, the envelope area has no obvious change with the increase of clamping angle. 4) In soft rock, the envelope shape of the resistance body is a curve that is convex toward the outside of the anchorage; when it is hard rock, it tends to be a curve that is concave toward the inside of the anchorage. 5) Under the condition of hard rock, the integral deformation of surrounding rock on both sides of the tunnel-type anchorage is more obvious, which means that the load transfer range is wider and the clamping effect is more obvious. 6) The ultimate bearing capacity increases with the increase of the clamping angle, and shows a linear change trend. 7) Faults significantly weaken the bearing capacity of tunnel-type anchorage, but the impact of faults at different angles is slightly different. Finally, the whole process of deformation and failure of surrounding rock is intuitively displayed, and the load transfer mechanism can be peeped from it.

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As cities continue to expand, the demand for effective underground infrastructure to address urban transportation challenges has increased. Tunnels, particularly those constructed using the New Austrian Tunneling Method (NATM), play a crucial role in managing these challenges. This study investigates the deformation behaviors of NATM tunnels under three different cover depths (17 m, 26 m, and 56 m) using the Finite Element Model (FEM) under static loading conditions. The main objective is to analyze the impact of varying cover loads on the stability and structural integrity of egg-shaped tunnel geometries, which are commonly preferred by designers. The analysis investigates deformations during excavation, focusing on both tunnel convergence and surface settlement, in a four-layered ground profile consisting of weathered soil, weathered rock, soft rock, and hard rock, respectively. By comparing these deformations under different cover loads, this study highlights critical factors influencing tunnel design and provides valuable insights for ensuring the safety and efficiency of shallow tunnel construction, particularly in multi-layered rock formations. Key findings indicate a maximum vertical displacement of -11.50 mm at the top of the final lining and a maximum compressive thrust of 155 t/m in the deepest case, demonstrating a non-linear structural response to increasing cover depth. The results, supported by graphical representations, demonstrate the importance of precise cover load calculations in tunnel stability and contribute to the development of engineering guidelines for similar projects.

In order to mitigate ground deformation during shield construction in both upper soft and lower hard strata of coastal areas, a numerical simulation was executed. This simulation assessed surface deformation under varying stratum ratios, grouting pressures, and earth bin pressures. The evaluation was primarily based on the amount of ground deformation, which revealed that hard rock strata offer superior settlement control compared to soft rock strata. The excavation of the right tunnel line increased disturbance to the left line at higher stratum ratios. Surface deformation demonstrated a linear correlation with earth pressure, with 130 kPa identified as the optimal point. Higher pressures resulted in extrusion deformation and ground uplift. Grouting pressure had a minimal impact on stratum deformation over time. The stratum ratio exerted the most significant influence on settlement, followed by earth pressure, with grouting pressure having the least impact. In the context of coastal tunnel construction, hard rock excavation is favored. Earth pressure must be balanced to prevent subsidence or uplift, while excessive grouting pressure does not significantly reduce subsidence. Grouting pressure should ensure the complete filling of voids.

This research was undertaken to predict the result of vault settlement during the excavation of super-large-span tunnels in soft rock strata, which are prone to deformation and hard to predict aftermaths. Numerical simulation was applied to tackle with vault problems during excavation of super-large-span soft rock tunnels such as proneness to deformation and hard prediction on vault settlement. As a result, a model for continuous prediction of vault settlement as the tunnel face keeps advancing was proposed, with influencing factors such as excavation span and tunnel depth taken into consideration, and put forward the optimization of super-large-span variable-section tunnels construction scheme. The results show that the vault settlement becomes fast at the beginning of the excavation because its surrounding rocks are characterized by weakness, incompleteness, and poor stability. At the initial stage of excavation, the varying tunnel depth had a greater impact on vault settlement, indicating that the primary support has to be enhanced at the beginning of the excavation of a vault with weak surrounding rocks. As the excavation of pilot tunnels proceeds, the high-stress zone transfers to the deep part of the surrounding rocks. The tunnel vault settlement model is capable of rapidly predicting the vault settlement at locations other than the observation points. The final settlement amount is affected by the excavation span, the tunnel depth, and the basic mechanical parameters of surrounding rocks. The key to the construction of a super-large-span and variable cross-section tunnel lies in the cross-section varying parts where the stress is concentrated, thus requiring reinforcement and frequent monitoring. The research methods and analysis may provide basic data and technical means for the control of the vault settlement of large-span tunnels in soft rock strata.

In order to study the creep behavior of the surrounding rock of the interbedded rock mass tunnel considering the time-dependent deformation, this paper proposes a viscoelastic-plastic seven-element model considering the stress threshold, and derives and establishes its creep equation under three-dimensional stress state. At the same time, the UMAT (User-defined Material) subroutine of the model is developed based on the ABAQUS software. The rationality of the seven-element model and the effectiveness of the subprogram are verified by rheological test results. Finally, the UMAT subroutine is applied to the numerical simulation of the creep behavior of soft and hard interbedded rock tunnels with different rock inclinations ( α ). The results show that the different rock inclination angles have different effects on the horizontal displacement of the ground above the tunnel, settlement deformation, and the convergence of the tunnel section. With the increase of the rock inclination (0 ≤  α  ≤ 90°), the horizontal displacement of the surface on both sides is antisymmetric. When α is 0°, 45° and 90°, the horizontal displacement on both sides is equivalent. Surface subsidence decreases and then increases slowly. When α is 0° and 45°, the surface subsidence is the largest (12.4 mm) and the smallest (11.1 mm), respectively. The convergence values of the tunnel section change according to different parts of the tunnel. The convergence values of the arch top and arch bottom decrease continuously, and their maximum convergence values are 23.4 mm and 17.3 mm, respectively. The change trend of the arch waist and arch shoulder convergence values is the opposite. When α is 0°, the convergence value of the arch waist is maximum (3.5 mm). When α is 15°, the convergence value of the arch shoulder is the maximum (2.0 mm).

The research in this paper relies on the Baochang shield construction section of Jinan Metro Line R2 and uses MIDAS GTS and MIDAS GEN to construct a three-dimensional calculation model to numerically simulate the process of shield tunneling through abrupt geology. The main research focuses on surface settlement and building deformation during excavation, as well as monitoring of building deformation and surface settlement after adopting settlement control measures. The research results are as follows: The maximum settlement of tunnel excavation from hard rock to soft rock and from soft rock to hard rock occurs at the longitudinal center of the tunnel, with values of 1.66 mm and 4.82 mm. The excavation direction has a significant impact on surface deformation. The tunnel is excavated from hard rock to soft rock and the maximum deformation values in the vertical and horizontal directions of the building are 2.04 mm and 1.92 mm. After adopting settlement control measures, surface settlement and deformation of buildings were monitored. The monitoring results showed that the deformation monitoring values of the surface and buildings, after adopting engineering measurements, were lower than the values of numerical simulation. This indicates that the engineering control measures adopted can effectively constrain surface settlement and the deformation of buildings.

This paper introduces ZDY1200G lightweight underground drilling rig. The feeding device was designed with light alloy material and the deformation of the fuselage was measured by 3D DIC speckle deformation measurement. A high-speed gyrator with large through hole for hard rock coring was designed. A hydraulic system based on constant pressure variable displacement pump was developed, which included feed linkage and rotary linkage. The drilling rig has been applied in the Cangyuan lead-zinc mine in Yunnan Province. A rope coring drilling hole with 512.68 m depth and 76 mm diameter has been completed. The reliability and technological advancement of the whole set of equipment have been verified, which provided technical support for the exploration of the Cangyuan lead-zinc mine and also mining areas with similar conditions.

It is usually hard to ensure overall stability and construction safety when tunneling in weak rock. Therefore, it is of practical engineering significance to conduct safety monitoring reference value study based on numerical ultimate load analysis by building an equivalent rock model. In this paper we investigate ultimate strains of equivalent rock masses of different classes based on numerical ultimate load analysis by building an equivalent surrounding rock model; examined the deformation reduction factor changes for different classes of surrounding rock by building a plane model for calculation and analysis; established tunnel stability assessment criteria through observation of ultimate shear strain diagrams under different reduction factors; and determined appropriate management measures according to warning levels. Our analyses show (1) under different loads the higher the rock mass classification the smaller its vertical displacement and hence its ultimate strain; (2) the higher the rock mass classification the more susceptible it is to strength, creep and instabilities; (3) Assessment criteria are established by comparing displacement U measured during tunneling with the ultimate displacement U0, i.e. the tunnel is stable if U < U0 and unstable if U > U0.

According to the geological characteristics of Xinjiang Ili mine in western area of China, a physical model of interstratified strata composed of soft rock and hard coal seam was established. Selecting the tunnel position, deformation modulus, and strength parameters of each layer as influencing factors, the sensitivity coefficient of roadway deformation to each parameter was firstly analyzed based on a Mohr-Columb strain softening model and nonlinear elastic-plastic finite element analysis. Then the effect laws of influencing factors which showed high sensitivity were further discussed. Finally, a regression model for the relationship between roadway displacements and multifactors was obtained by equivalent linear regression under multiple factors. The results show that the roadway deformation is highly sensitive to the depth of coal seam under the floor which should be considered in the layout of coal roadway; deformation modulus and strength of coal seam and floor have a great influence on the global stability of tunnel; on the contrary, roadway deformation is not sensitive to the mechanical parameters of soft roof; roadway deformation under random combinations of multi-factors can be deduced by the regression model. These conclusions provide theoretical significance to the arrangement and stability maintenance of coal roadway.

The primary support arch-cover method is a construction excavation that can effectively deal with upper soft and lower hard strata, but its deformation sensitivity is relatively large in shallow buried strata, and there are still problems in applicability when it occurred to large spans. This paper takes a hidden excavation station in Qingdao as the research background, and uses FLAC-3D simulation software to carry out numerical simulation calculations for the entire excavation of the primary support arch-cover method. The study analyzes the changes in stress and displacement of surrounding rocks under different excavation procedures. The results show that the excavation of the middle diversion tunnel is the process where the stress of the surrounding rock changes the most; the maximum stress and displacement of the rock and soil in the upper part of the station cavern happens when the arch structure is excavated; the surrounding rock remains basically unchanged during the excavation of the lower section. The safety and stability of the excavation process indicates that the method can be applied to metro stations in shallow buried hard rocks, providing a certain reference for similar projects.

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With the further development of China’s coal resources, mining operations are constantly transferred to the deep soft rock. As such, the mine roadway is under the action of high geostress, the surrounding rock body engineering properties are poor, the overall strength is low, the traditional support method struggles to meet the needs of safe production, and the surrounding rock control has become a major technical challenge. This paper relies on the actual project, analyzes the destabilization mechanism of the roadway, analyzes the deformation of the peripheral rock of the deep roadway, determines the physical and mechanical parameters of the peripheral rock through indoor tests, establishes numerical analysis model, proposes to adopt the joint support scheme of anchor rods + anchor cables + a 36U-type steel metal bracket + a laying net + a laying mat + filling behind the wall, and monitors the displacement of peripheral rock of the roadway on a regular basis by using the numerical display convergence meter, and then obtains the displacement of the peripheral rock of the roadway after excavation as well as under the influence of the quarrying movement. Under the influence of the roadway perimeter rock displacement, we evaluate the reasonableness of the support program, as well as the safe and effective control of the roadway perimeter rock, to achieve the ideal roadway perimeter rock support and control effect.

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: Based on the spiral tunnel group of Xinjin expressway, this paper takes the typical deep buried soft broken section of Hankou tunnel as the research object. On the basis of the composite lining structure with primary support and secondary lining, considering four working conditions: the presence or absence of systematic rock bolts and advanced small pipes. Utilizing the ABAQUS numerical simulation platform, refined numerical simulations of the entire construction process are conducted and compared with field-measured engineering data. The results indicate: (1) Under all four working conditions, the vault settlement and horizontal convergence exhibit a pattern of slow growth, followed by rapid growth, and eventual stabilization during tunnel excavation. When excavating the core soil of the upper bench after installing the primary support, the rate and magnitude of

The Muzhailing highway extra-long tunnel is affected by high geostress, and during the construction, large deformation of soft rock frequently occurred. Taking this as the research background, the high-prestressed constant resistance and large deformation anchor cable support scheme was proposed. In the field test, the indicators of three support schemes were compared, including the convergence deformation of surrounding rock, the deep displacement of surrounding rock, the axial force of anchor cable and bolt, and the stress between primary support and surrounding rock. The field test results show that: under the support of bolts, the cumulative deformation of surrounding rock exceeded 1500 mm, and the primary support damage was serious; In the second scheme, under the support of 4 m and 5 m long constant resistance anchor cables, although the large deformation of surrounding rock was controlled, the cumulative deformation was about 600 mm; In the third scheme, under the support of 5 m and 10 m long constant resistance anchor cables, the cumulative maximum deformation of surrounding rock was reduced to 216 mm, and all the data of the field test were within the controllable range. Therefore, high prestressed constant resistance and large deformation anchor cable support measures can effectively control the large deformation of surrounding rock.

Squeezing phenomena can lead to severe loads in deep tunnels, especially in the presence of a low ratio of surrounding rock strength to overburden pressure. For this reason, it is highly imperative to analyze and identify a suitable methodology to estimate the squeezing potential and select a proper support system of rock mass. This study aims to reveal the causes of failure of Tishreen tunnel in the west of Syria and develop remediation measures accordingly so as to bring the tunnel back into service. The tunnel in question was subjected to successive failures such as buckling and spalling of side walls, floor heave, and extremely large convergence reaching the failure state of the tunnel lining. In this study, an effective way was demonstrated to evaluate the squeezing potential of the tunnel lining and appropriate modeling of the long‐term response of a tunnel excavated in weak rock. Specifically, the causes of failure of Tishreen tunnel were first evaluated by empirical approaches. Then, a numerical model was developed using a time‐dependent constitutive model to investigate the time‐dependent response of the tunnel lining. On this basis, this study proposed an effective reinforcement schemes including steel ribs, grout injection, ground anchors, and new lining of reinforced concrete. The results show that the Burger viscoplastic model simulates effectively the resulting deformation and creep behavior of squeezing ground. It is also observed that using a combined heavy support system can provide efficient control over squeezing deformation and maintain the serviceability of the tunnel under study.

This study focuses on monitoring the deformation of the shallow unsymmetrical section of a super-large-span tunnel portal relying on the newly built Shimentangshan Tunnel, and through numerical simulations, the construction sequence and drift ratios were optimized to address challenges related to the stability of surrounding rock and structure. The findings indicate that employing the double-side drift method results in a maximum settlement value of 107.0 mm and a maximum convergence value of 108.8 mm, leading to larger deformations. Excavating the shallow buried side first followed by the deep buried side proves beneficial for deformation control of the support structure and effectively limits damage to the surrounding rock. A drift ratio of 0.3 ensures optimal support structure security and stability. Considering both structural deformation and surrounding rock damage, a ratio between 0.25 and 0.35 for the drifts is recommended. Taking into account construction efficiency and economic benefits, a construction plan for the shallow buried unsymmetrical section at the portal of super-large-span tunnels is proposed.

When traversing a complex and fractured geological formation, a deep-buried highway tunnel in Yunnan Province encountered a significant uplift problem in the invert. The causes of the tunnel’s uplifted section were analyzed through on-site observations and monitoring of the lining structure’s deformation, combined with numerical simulation methods. The results indicate that the primary factors leading to the invert uplift are the softening of the surrounding rock at the invert base due to water seepage and the high water pressure in the fractured zone. The softening of the surrounding rock is crucial to the safety of the inverted uplift structure. Based on the tunnel’s engineering characteristics and the causes of the invert uplift, remediation measures such as “enhancing the drainage system, grouting with steel flower pipes, and demolishing and replacing the invert” were adopted. These measures effectively controlled the invert uplift. After the remediation, the convergence rate of the secondary lining decreased, and the deformation stabilized, indicating that the invert uplift remediation plan was reasonable and effective Analysing the causes of tunnel uplift through numerical simulation. Propose measures to deal with the uplift of the tunnel arch. The treatment plan can effectively control the damage to the uplift arch. Analysing the causes of tunnel uplift through numerical simulation. Propose measures to deal with the uplift of the tunnel arch. The treatment plan can effectively control the damage to the uplift arch.

Taking the Jiangluling Carbonaceous Shale Tunnel as an example, this study aims to investigate the mechanism of large deformation and design construction technology of carbonaceous shale tunnels. Using theoretical analysis and comparative analysis of numerical simulation and field measured data, the mechanism, mechanical properties, and causes of large squeezing deformation of the Jiangluling Tunnel were analyzed. The study results are as follows: 1) Six failure modes of the support structure can be generated due to the large deformation of the surrounding rocks during the construction of Jiangluling Carbonaceous Shale Tunnel; 2) The causes of large deformation during the construction can be divided into internal and external causes; 3) The deformation degree of the surrounding rock of Jiangluling Carbonaceous Shale Tunnel increases with the burial depth in an approximately linear manner. Under deep-buried conditions, horizontal convergence is more severe than vault settlement in carbonaceous shale tunnels; 4) The deformation of the construction cavern of the Jiangluling Carbonaceous Shale Tunnel typically includes the displacement before tunnel face excavation, tunnel face deformation, and deformation behind the tunnel face. The advance displacement accounts for 30.73% of the total displacement. The influence range of advance displacement is 1-1.2D in front of the tunnel face. These results can provide a reference for the design and construction of carbonaceous shale tunnels.

Mechanized excavation via tunnel boring machines (TBMs) could contribute to significantly reducing construction time and costs. However, problems stemming from extreme geological conditions can cause a variety of issues, such as the potential of TBM jamming. Based on the time-dependent behavior of silty mudstone, the present work focuses on investigating the complex interaction between the surrounding rock and the tunnel machinery. A case study was also discussed that provides a theoretical basis for planning the actual project excavation along the tunnel. Comprehensive theoretical calculation methods are used to determine the radius of the plastic zone, the maximum total thrust of the non-jammed TBM, and the convergent deformation. To avoid jamming the TBM, the rated thrust of the TBM should be greater than the maximum total thrust force experienced by the auxiliary thrust cylinders, and the convergence deformation of surrounding rock should also be less than the expected deformation.

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The application of convergence-confinement analysis in tunnel engineering serves as a conventional initial approach to evaluate wall movements and devise support frameworks in scenarios involving swelling rock. This analytical technique relies on either a closed-form solution or a finite element method (FEM) utilizing a plane strain numerical model. A crucial component of this analysis is the longitudinal displacement profile (LDP), which is essential for linking the displacements of tunnel walls during the excavation process. The evaluation is performed along the tunnel’s axis. In this research, the LDP formulation proposed by Vlachopoulos and Diederichs (2009) is employed to assess how factors such as the distance supported from the tunnel face (working surface), as well as the spacing of rock bolts—both diametrically and transversely—affect the safety factor and the maximum plastic radius produced during installation. The calculations are premised on the understanding that optimal conditions are influenced by variations in the plastic zone’s size, with larger zones requiring more extended normal excavation distances. Mistakes in applying the LDP can lead to substantial errors in determining the correct distances for installing tunnel support systems, potentially resulting in failures of temporary supports. This paper details the findings obtained from the analytical solutions utilized in this investigation.

The prediction and early warning of tunnel collapse in weak surrounding rock is very important for tunnel construction safety, but the current monitoring methods are insufficient. In view of the shortcomings of existing monitoring methods for deformation of advanced core soil, a monitoring method of pre-convergence deformation of advanced core soil in front of the tunnel face was proposed; this involves placing an array displacement meter (ADME) in a leading small conduit and monitoring the deformation of the leading small conduit. The coupling accuracy test data of the ADME and steel pipe were combined to prove the feasibility of the device and test method. Finally, it is proposed to place the ADME in the lead duct, calculate the displacement of the measuring unit through the change of gravity and angle, and obtain the pre-convergence deformation of the lead core soil in front of the palm face. The results show that the floating error of the measuring unit of the ADME is 0.2 mm by calibrating the precision measuring device designed by itself. The absolute error is 0.2 mm @ 1 m. When the ADME is used for deformation measurement with displacement greater than 2 mm @ 1 m, the relative error can be controlled within 10%. Through the above deformation monitoring system, it is expected to realize a real-time monitoring method which can ensure monitoring accuracy and frequency, reduce interference to tunnel construction, and improve the safety and accuracy of tunnel construction in weak surrounding rock.

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How to evaluate the reliability of deep soft rock tunnels under high stress is a very important problem to be solved. In this paper, we proposed a practical stochastic reliability method based on the third-generation non-dominated sorting genetic algorithm (NSGA–III) and eXtreme Gradient Boosting (XGBoost). The proposed method used the Latin hypercube sampling method to generate the dataset samples of geo-mechanical parameters and adopted XGBoost to establish the model of the nonlinear relationship between displacements and surrounding rock mechanical parameters. And NSGA–III was used to optimize the surrogate model hyper-parameters. Finally, the failure probability was computed by the optimized surrogate model. The proposed approach was firstly implemented in the analysis of a horseshoe-shaped highway tunnel to illustrate the efficiency of the approach. Then, in comparison to the support vector regression method and the back propagation neural network method, the feasibility, validity and advantages of XGBoost were demonstrated for practical problems. Using XGBoost to achieve Monte Carlo simulation, a surrogate solution can be provided for numerical simulation analysis to overcome the time-consuming reliability evaluation of initial support structures in soft rock tunnels. The proposed method can evaluate quickly the large deformation disaster risks of non-circular deep soft rock tunnels.

Under asymmetric three-dimensional high in-situ stress and high pore water pressure, tunnels are subjected to complex stress conditions, making them susceptible to failure and posing a threat to water conveyance safety. This study focuses on a large-scale cross-basin water diversion tunnel from Datong river into Huangshui river, which characterized by ultra-deep and complex geological conditions. Based on the field measurement data, a parameter inversion method considering the deformation of tunnel surrounding rock at multiple characteristic points is proposed. Additionally, considering the fluid-structure interaction effects under the influence of asymmetrical three-dimensional high in-situ stress and high pore water pressure, the stress-deformation characteristics of the soft rock tunnel are studied, and the damage evolution characteristics of the surrounding rock under different in-situ stresses and pore water pressures are analyzed. The results manifest that intense mutual extrusion of the surrounding rock, leading to volumetric compression, is the primary cause of the formation of stress concentration and excess pore water pressure. Additionally, the maximum deformation and the most likely location for gushing water both occur at the tunnel’s waist. After the implementation of segment support measures, the deformation control effect on the surrounding rock is remarkable. Notably, the reduction in damage depth across various characteristic locations due to segment support shows minimal variation. However, in terms of the reduction in disturbance depth, the tunnel waist significantly outperforms the top and bottom positions. The damage depth of the tunnel surrounding rock is positively correlated with both in-situ stress and pore water pressure, but it is more significantly influenced by in-situ stress than by pore water pressure. These findings can offer some valuable insights and guidance for future similar tunnel construction project.

After the excavation and unloading of deep-buried soft rock tunnels, support structures often experience deformation-related disasters such as concrete cracking, steel frame bending and twisting, and primary support instability under different forms of load. Accurately calculating the load borne by the primary support structure is the key to ensuring design rationality and construction safety. Especially in layered soft surrounding rock formations, the magnitude and distribution of the loads are different from those of conventional rock and soil masses, resulting in limited applicability of existing load calculation methods to similar formations. Therefore, based on the measured deformation of the tunnel structure, while considering the different geometric forms of the primary support structure during partial excavation, this paper proposes a deformation-structure (D-S) load calculation method. By comparing the calculation results of this method and a large number of sample data for typical deep-buried layered soft rock tunnels, the reliability of the D-S load calculation method is verified. In addition, the variation law of the loads during the tunnel construction period is enunciated, and the magnitude and distribution of the loads acting on the primary support are clarified. The D-S load calculation method provides a theoretical basis for load calculation in deep-buried layered soft rock tunnels.

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Due to the special engineering geological characteristics of weak interlayer zone (WIZ) with the initial shear, the pre-consolidation, the water softening and clay generation, that occurs between different rock strata (e.g., tuff and basalt), it tends to represent potential threats to the overall stability of large underground cavern under high geostress, such as the large deformation of upper and lower rock masses, structural stress-induced collapse and the time-dependent plastic squeezing-out failure, which could never be neglected, and requires more widespread concern. Focusing on the prediction and analysis of such stability issues induced by WIZ, a novel constitutive model for WIZ, based on the unearthed macro-meso mechanical response of WIZ under complicated unloading stress paths, has been first established, and well embed into the effective numerical calculation platform, to realize the quantitative descriptions of the mechanical effects of stress path, the particle breakage as well as the mechanical parameter evolution of WIZ. Then the rock failure index for WIZ (RFDwiz) was derivated, to help determine the cracking scale, depth and degree of surrounding rock masses with WIZ. Based on the proposed model, the RFDwiz and the cracking-restraint design method, the prediction of the failure position and degree, as well as the dynamic optimization design of the reasonable supporting parameters of rock masses with WIZ in underground cavern, were ultimately realized. This study will provide theoretical basis for the analysis and prediction of the instability of deep underground projects controlled by rock masses with WIZ.

Accurate penetration rate prediction enhances rock-breaking efficiency and reduces disc cutter damage in tunnel boring machine (TBM) construction. However, this process faces significant challenges such as the high uncertainty of ground conditions and the complexity of maintaining optimal TBM operation in long and large tunnels. To address these challenges, we propose TCN-SENet++, a novel hybrid multistep real-time penetration rate prediction model that combines a temporal convolutional network (TCN) and a squeeze-and-excitation (SENet) block for aided tunneling. This study aims to demonstrate the application of TCN-SENet++, as well as other models such as RNN, LSTM, GRU, and TCN, for TBM penetration rate prediction. The model was developed using actual datasets collected from the Yin-Song diversion project. We employ a 30-s time step to predict the future time steps of the penetration rate (1st, 3rd, 5th, 7th, and 9th). The features that influence the penetration rate, such as the cutterhead torque, thrust, and cutterhead power, were considered. A comparative analysis using the mean absolute error and mean squared error revealed that the TCN-SENet++ model outperformed the other models, including RNN, LSTM, GRU, TCN, and TCN-SENet+. In comparison, TCN-SENet++ achieved average MSE reductions of 18%, 6%, 3%, 1%, and 2%, respectively. The TCN-SENet++ model demonstrated fewer errors in the new project, validating its effectiveness and suitability for real-time penetration rate prediction in TBM construction.

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During metro tunnel construction, Tunnel Boring Machine(TBM) often induces surface and nearby pile vibrations. However, these vibrations are often overlooked due to the short-term passage of the cutterhead beneath the foundation structures. In fact, these vibrations had adverse effects on certain sensitivity structures. Therefore, to analyze the dynamic characteristics of environmental vibrations induced by TBM, on-site vibration monitoring and a numerical modeling method coupling Discrete Element Method with Finite Difference Method were employed for the research. The study focused on a metro tunnel segment passing beneath the foundation of an interchange bridge. The results show that the acceleration of the cutterhead vibration reached 2.55 g during tunnel boring machine operation, with the nearest segment to the cutterhead experiencing a maximum vibration displacement 20% of that at the cutterhead. In weathered limestone formations, when the tunnel depth is less than 10 m, peak accelerations of the ground directly above the excavation face exceed 0.05 g, while pier accelerations reach 0.005 g. Due to cutterhead vibrations, the piers above pile foundations experience low-frequency vibrations (< 12 Hz), with four peak segments identified in the frequency domain, and vibration energy primarily concentrated between 7 and 10.6 Hz. Numerical simulation data based on the DEM-FDM coupling method indicates a negative exponential relationship between peak acceleration and frequency of piles, with a linear positive correlation with amplitude. Piles exhibit the highest sensitivity to vibrations below 4 Hz. Sensitivity analysis results indicate that during tunnel construction, nearby piles are most sensitive to the frequency of the vibration source, followed by the amplitude of the vibration source and the spacing between piles and the tunnel.

To investigate the arching effect of shallow buried hard rock tunnels under overlying load, the engineering scenario of a subway station on Qingdao Metro Line 6 is utilized. A large-scale tunnel loading model test is conducted, in conjunction with finite element numerical simulations, to analyze the impact of various overburden ratios on strata arching. The results show that: when the tunnel excavation span is certain, with an increase in the overlying rock mass, the stress diffusion process of the surrounding rock can be better accomplished to form the arch effect. This means that the thickness of the overburden of the tunnel determines whether or not the surrounding rock appears to have a stratified arch effect. When the tunnel overlying rock thickness is certain, the span of the tunnel determines the shape of the formation into an arch, that is, the curvature of the arch. The joint surface is an important factor in tunnel stability. When the overlying load increases to a certain value, the rock mass at the joint plane slips relatively, leading to the displacement phenomenon of the surrounding rock, which then affects the formation and shape of the formation arch.

The frequent and complex stress variation of surrounding rock and load transfer of the lining structure during the construction of large-span double-arch tunnels pose certain challenges to subsequent construction control. This study employs a combination of physical model and numerical simulation to investigate the mechanical response of large-span double-arch tunnels during construction, and develops relevant model testing equipment and monitoring systems to provide references for similar tunnel mechanical response studies. The results show that: (1) The displacement and deformation of tunnel structures during construction experience three stages: " Slow deformation → Rapid deformation → Convergence deformation," with the settlement deformation on the same side accounting for over 80% due to construction in the same direction. (2) During excavation, the stress variation of surrounding rock and lining structures undergoes three processes: "Stress concentration → Stress release → Stress stabilization." The horizontal load transferred by the initial support causes abrupt changes in the horizontal thrust of the partition wall, while the vertical load induces an eccentric loading effect on the partition wall towards the leading side. This eccentric loading effect reaches its maximum when the leading side’s bench III is excavated to the left tunnel and decreases to a minimum and stabilizes when the excavation of the right tunnel’s monitoring face is completed. (3) The influence on tunnel crown settlement is in the order of Step I> Step II > Step III, while the influence length on surrounding rock stress is in the order of Step II > Step III > Step I. Therefore, these construction steps should be closely monitored initially. (4) Due to asymmetric construction, the partition wall of the double-arch tunnel is subjected to eccentric loading from the initial support load and the overlying surrounding rock load on the leading side. This effect improves as the trailing side is excavated, but the section bending moment still exhibits a "W" shape with flatter ends. The eccentric loading effect persists, increasing the risk of lateral displacement, bending-torsion, and shear failure of the partition wall.

The stability of underground openings in weak rocks presents a major challenge in geotechnical engineering due to the time-dependent deformation and low mechanical strength of such materials. This study analyzes total displacement in tunnel structures with and without support systems, focusing on the Cileunyi "“ Sumedang - Dawuan toll road tunnel in West Java. Using a 3D finite element modeling approach (Phase2 software), comparisons were made between two tunnel spacing configurations (3R and 5R). The results show that the installation of support systems such as steel ribs, wire mesh, and shotcrete significantly reduces displacement, especially on critical zones like the tunnel"™s left wall. The 3R model recorded a maximum displacement difference of 46.3 mm, while the 5R model showed 44.9 mm. This study confirms that proper support configuration not only minimizes deformation but also promotes more uniform stress redistribution. The findings highlight the importance of integrating empirical data with numerical simulations for effective tunnel support design in weak rock environments.

Hanging tunnels are a unique type of highway constructed on hard cliffs and towering mountains, renowned for their steep and distinctive characteristics. Compared to traditional full tunnels or open excavations, hanging tunnels offer significant advantages in terms of cost and construction time. However, the engineering design and construction cases of such tunnels are rarely reported, and concerns about construction safety and surrounding rock stability have become focal points. Taking the Shibanhe hanging tunnel as a case study, this paper focuses on the stability of the surrounding rock during the excavation of limestone hanging tunnels using physical analog model (PAM) experiments and numerical calculation. Firstly, based on the similarity principle and orthogonal experiments, river sand, bentonite, gypsum and P.O42.5 ordinary Portland cement were selected as the raw materials to configure similar materials from limestone. Secondly, according to the characteristics of hanging tunnels, geological models were designed, and excavation experiments with three different sidewall excavation widths and rock wall slopes were carried out. The effects of these variables on the stress and displacement behavior of the surrounding rock were analyzed, and the laws of their influence on the stability of the surrounding rock were explored. Finally, numerical simulations were employed to simulate the tunnel excavation, and the results of the numerical simulations and PAM experiments were compared and analyzed to verify the reliability of the PAM experiment. The results showed that the vertical stress on the rock pillars was significantly affected by the sidewall excavation widths, with a maximum increase rate of 53.8%. The displacement of the sidewall opening top was greatly influenced by the sidewall excavation widths, while the displacement of the sidewalls was more influenced by the rock wall slope. The experimental results of the PAM are consistent with the displacement and stress trends observed in the numerical simulation results, verifying their reliability. These findings can provide valuable guidance and reference for the design and construction of hanging tunnels.

Alkali injection treatment is a key method for stabilizing surrounding rock containing H2S. To examine the deformation of surrounding rock with and without coal seams under different excavation methods and Alkali injection treatments, the finite difference method for single-hole Alkali injection, double-side-wall excavation, and three-bench excavation is simulated. The results indicate that, under the same excavation method, compared with no Alkali injection, the displacement of the vault increases by 23.37% to 24.33% for a 3% Alkali concentration and by 34.55% to 42.70% for a 5% concentration. The horizontal convergence of side walls increases by 18.20% to 25.53% for a 3% Alkali treatment and by 46.20% to 61.08% for a 5% Alkali treatment. When two coal seams tilt through the working face, the deformation of the lower layer is more significant than that of the upper. The greatest deformation occurs at the intersection of the lower layer and the excavation line. Under different Alkali injections, compared with the three-bench excavation method, the vault settlement of the double-side-wall excavation method decreases by 7.65% to 11.37% and the horizontal convergence of sidewalls decreases by 22.80% to 72.27%. When the surrounding rock contains coal seams and is treated with Alkali injection, it is recommended to use the double-sided excavation method.

When the Xiaojiazhai tunnel is constructed by the double-wall method, different curvature radii have different effects on controlling the stability of the surrounding rock and speeding up the construction progress. By numerically simulating the tunnel excavation under different radius of curvature, it is concluded that R is adopted respectively. The deformation displacement of surrounding rock is =11.6m∠520 and R=5.76m∠1060. The maximum horizontal displacement and vertical displacement are smaller when R=5.76m∠1060 is selected. According to the analysis results, when R=5.76m∠1060 is selected, the deformation of surrounding rock can be controlled to ensure the safety of construction and provide reference for future construction.

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According to the problem of deformation of surrounding rock when the double-wall method is adopted in the tunnel, the five tunnel monitoring points are set in the tunnel vault, arch waist and arch foot to simulate the tunnel excavation process. The surrounding rock is deformed, and the excavation of the middle guide hole makes the deformation of the surrounding rock reach 7.2mm. After the removal of the middle partition wall, the deformation reaches the maximum, which is 8.4mm. The horizontal displacement starts to increase rapidly, and the maximum is 5.3mm. According to the analysis results, the surrounding rock above the tunnel should be reinforced in time, and the deformation of the surrounding rock after the removal of the middle partition wall should be paid attention to ensure the construction safety and provide reference for future construction.

In the process of coal seam mining, there are often hard thick key layers in the overlying strata. Due to the high strength and good integrity of the hard thick key layer, after the hard thick key layer is broken, the overlying strata will collapse and lose stability in a large area, which is very easy to induce dynamic disasters such as rock burst, mine earthquake, coal wall caving, and roof slab caving. Aiming at the hard and thick key layer overlying the working face, the dynamic response of the mine under the strong mine earthquake induced by the breaking of the main key layer of high-level magmatic rock is numerically simulated and analyzed by using FLAC2D numerical simulation software, and the variation laws of the stress field, displacement field, and velocity field of the coal seam roadway under different boundary conditions and different focal heights are studied. The research shows that the roof of solid coal roadway is prone to vibration in a small range, and the displacement increases and decreases with the disturbance. The displacement of the floor and two sides of the solid coal roadway and the top floor and two sides of the roadway along the goaf continues to increase in the initial stage of the disturbance, and the displacement will remain stable with the continuation of the disturbance. The displacement of both sides and roof and floor of gob roadway can reach stability in the later stage of disturbance, and with the increase of the number of adjacent goaf, the longer it takes for the displacement of surrounding rock to reach stability. When the focal height is lower than 90 m, the variation of surrounding rock response increases sharply with the decrease of focal height. When a strong earthquake occurs in the low rock stratum, the impact damage of roadway surrounding rock is almost inevitable. The influence degree of strong earthquake on the stability of roadway surrounding rock is arranged as follows: gob-side roadway (mined out on one side) > solid coal roadway (mined out on both sides) > solid coal roadway (mined out on one side). The evolution process also shows that the working face boundary conditions have an important influence on the energy propagation of mine earthquake. With the increase of the number of adjacent goafs, the faster the energy attenuation rate of mine earthquake propagation is. The research results have important reference significance for the safe mining of working face under similar geological conditions.

The tunnel boring method (TBM) is a widely used and effective tunneling technology in various rock mass quality circumstances. A “faulted rock mass” can range from a highly fractured rock mass to a sheared weak rock mass, making the ground conditions challenging for tunneling, especially for TBMs. “Faulted rock” significantly affects hard rock TBMs, primarily due to the TBM’s high geological risk and poor flexibility. TBMs require careful planning and preparation, starting with preliminary assessments. This study investigates the impact of establishing an isolation material between a circular tunnel and the adjacent faulting rock on seismic response. The two parts of the parametric analysis for the isolation material utilized in the model look at how changes in the mechanical characteristics of the material, such as the shear modulus of the rock and the fault, affect the stresses created in the tunnel. The second section examines how changes in the isolation width concerning the fault width affect the stresses and displacements produced in the tunnel. Additionally, the effectiveness of isolating the tunnel during sudden changes in the characteristics of the rock was investigated under seismic loading perpendicular to the tunnel and parallel to the tunnel. The finite element approach was utilized to model the TBM tunnel and the neighboring rock with a fault or sudden change in the rock using Midas/GTS-NX, simulating the interactions between the rock and the tunnel. Time-history analysis using the El Centro earthquake was conducted to calculate the stresses in the tunnels during seismic events. Peak ground accelerations between 0.10 g and 0.30 g were utilized for excitation. A time step of 0.02 s and a length of 10 s for the seismic event were used in the analysis, with traditional grout pea gravel vs. the isolation layer. Comparisons were made between the absolute stresses (the greatest possible values) in the normal tunnel section (Sxx) and those induced in the tunnel with traditional grout and with isolation. Furthermore, the study of vertical displacement was taken into consideration. The seismic isolation method is highly effective in improving the seismic safety of bored tunnels. The results show that the significant values of the ratio between the shear modulus of isolation and the surrounding soil should be between 0.2% and 0.4%. Where parts of the tunnel run through a fault, the effective length of isolation should be between one and two times the fault width. The dynamic behavior of the tunnel with isolation is better than that with traditional grout. Generally, when isolation is used for any length, it reduces the stresses at the area of sudden change. Consequently, engineering assessments from both structural and geotechnical engineering viewpoints are now required for these unique constructions. An underground structure’s safety should be evaluated by the designer to ensure that it can sustain various applied loads, taking into account seismic loads in addition to construction and permanent static loads. Tunnels may be especially vulnerable in areas where the composition of the soil or rock varies.

Based on the engineering background of shield construction of a subway section in Chongqing, which needs to pass through a park and there is a lake inside this park, this paper adopts theoretical analysis methods and numerical simulation calculation methods to explore the distribution law of the seepage field and the characteristics of water pressure in lining segments during shield tunneling. The results show that, during the whole excavation of a double-track tunnel with EPB shield, the maximum vertical effective stress is about 4.24 MPa, which is located at the arch foot of the tunnel. The maximum effective stress in the horizontal direction is about 3.61 MPa, which is located on both side walls of the tunnel in the horizontal direction; after the left and right tunnels are excavated in sequence, a “double precipitation funnel-shaped” pore pressure distribution is formed around the tunnel; during the construction of the shield tunnel, the vertical displacement and horizontal displacement of the surrounding rock show an increasing trend and gradually tend to be stable values of 24.09 mm and 25.28 mm; the segment vault has settlement, the maximum settlement is 21.8 mm, the arch bottom has uplift, and the maximum uplift is 24.4 mm. The maximum horizontal displacement of the segment appears on both sides of the arch waist, and the maximum horizontal displacement decreases with the increase of excavation steps; the positive bending moment of the lining segment is mainly distributed on both sides of the arch crown, and the negative bending moment is mainly distributed on both sides of the arch bottom. The axial force of the lining segment is compressive stress, and the maximum axial force is mainly distributed on both sides of the arch waist. The maximum normal shear stress occurs on both sides of the segment arch bottom. The study conclusions provide theoretical foundation and a new guidance for long-term safety evaluation of underwater tunnel structures.

Double‐wheel trench cutters display reduced efficiency while cutting through hard or extremely hard rock strata, leading to significant wear on their picks. A high‐pressure water jet‐pick combined rock‐breaking method (HPC) for double‐wheel trench cutters is proposed, addressing the challenges of low efficiency and high pick wear when cutting hard rock strata. The HPC mode integrates high‐pressure water jets to precut grooves on both sides of the picks, creating free surfaces that facilitate rock fragmentation. Experiments were conducted with the combination of high‐pressure water jet cutting and linear pick cutting under the HPC mode with granite. The HPC rock‐breaking efficiency was compared with that of conventional pick‐relieved cutting (PRC) and pick‐unrelieved cutting (PUC) modes. A numerical model based on the continuum‐discontinuum element method was developed to investigate the rock‐breaking mechanism with water jet assistance. The mechanism of rock breaking by pick with bilateral water jet assistance has been revealed. The main conclusions are as follows: (1) The HPC mode reduced the average horizontal and normal rock‐breaking forces by 36.02% and 48.78%, respectively, compared with PRC, and by 32.07% and 42.85%, respectively, compared with PUC. Furthermore, compared with the PRC and PUC modes, the HPC mode decreased specific energy consumption by 88.58% and 93.84% and increased the coarseness index of rock debris by 159.28% and 189.77%, respectively. These improvements indicate a transition from localized fragmentation to large‐chunk stripping during rock breaking, attributed to the free surfaces created by water jet grooving. (2) The free surfaces created by the water jet altered the rock mass displacement vector from radial to horizontal, promoting the formation of Λ‐shaped fractures and increasing tensile and tensile‐shear fractures. This mechanism reduced the intermediate principal stress and strain energy within the rock mass, reducing the difficulty of rock breaking. The HPC mode thus offers a promising solution for improving the efficiency of double‐wheel trench cutters in hard rock excavation, with the potential for broader application in underground diaphragm wall construction.

Tunnel portal sections located in the soft-hard rock junction are vulnerable to the strong earthquake motions in seismically active regions. The main objective of this paper is to investigate the seismic response of tunnel portals located in the soft-hard rock junction. Taking the Baiyunding tunnel in northeast China as a background, a shaking table test with a geometric scaling ratio of 1:30 was built. Details of test setup and procedures are introduced first and then the test results are presented. The discussion of the results is based on the peak ground acceleration (PGA), the longitudinal, the contact stress, and the safety factor. The results show that the soft section of the soft-hard rock junction suffers remarkable damages under strong seismic motions, while the hard rock section is less affected by earthquakes. The increasing soft rock range causes a rise of the forced displacement of tunnel linings, which, together with the seismic inertia force, leads to the increase of the contact stress of the linings, and ultimately resulting in the deterioration of the tunnel seismic safety. To mitigate the seismic damage of tunnel portals in the soft-hard rock junction, rock grouting, bolt support, and other effective reinforced methods should be considered in the seismic design of the soft section.

According to field observation and theoretical analysis, the failure of the 1523103 reserved roadway is mainly affected by the lateral support pressure, rock mass strength, and support mode. With the mining of the 152309 working face, the lateral pressure of coal pillars on both sides of the reserved roadway increases, and since the lithology of the two sides and the floor of the roadway is weak, the reserved roadway experiences spalling and floor heave. Through numerical simulation, the distribution law of surrounding rock stress and the displacement of surrounding rock are obtained after the roof cutting and pressure relief of the reserved roadway with hard roof. According to the cause of surrounding rock failure of a reserved roadway, the combined control technology of roof cutting and pressure relief, grouting anchor cable support, and bolt support is put forward. After cutting the roof and releasing the pressure on the working face, the lateral support pressure of the two sides of the roadway is significantly reduced, the deformation of the two sides of the roadway is small, the maximum shrinkage rate of the section is reduced from 70% to 11%, and the deformation of the surrounding rock of the 1523103 reserved roadway is effectively controlled. The successful control of the surrounding rock in the 1523103 tunnel reduces the number of coal pillars to be installed, improves the coal extraction rate, and is conducive to the sustainable utilization of limited natural resources and the sustainable development of the coal industry.

For tunnel excavation with poor stability of surrounding rock, controlling the construction of key steps in each construction method is of great significance to tunnel construction. Taking Fengshuao and Daping tunnels as examples, this paper uses FLAC software to simulate three construction methods, i.e. double sides heading tunnel method, three-step method and CRD method. Through the analysis of displacement deformation in the numerical simulation results of three construction methods, it is concluded that the corresponding steps of maximum displacement deformation in different construction methods are the key steps in construction: the both sides heading method needs to strictly control the excavation of double-sided upper steps, the excavation of inverted arch and the dismantlement of middle-wall; the three-step method mainly controls the excavation of curved guide tunnel of upper steps, the excavation of inverted arch and the strike of locked bolts. The control steps of CRD method are the excavation of upper steps on the left wall, the excavation of upper steps on the right wall and the dismantlement of the middle wall. Therefore, strictly controlling the key steps of each construction method can improve the safety and efficiency of this kind of highway tunnel construction, and provide reference for future construction.

The cutter head, a pivotal component of the tunnel boring machine (TBM), endures high-risk working conditions involving high temperature, pressure, and hardness. The intricacy and variability of working conditions give rise to high torque, substantial thrust, and stochastic impact loads, ultimately leading to the damage and failure of the cutter head. In this paper, the mechanical and fatigue properties of the 8 -meter-class spoke-web composite cutter head have been investigated through the finite element method (FEM) more academically. Specifically, this article explores the typical working conditions (full load, eccentric load, and extreme condition) and different geologies (soft soil, composite formation, and hard rock) that the cutter head encounters. The findings demonstrate that under extreme working conditions, the cutter head experiences a maximum equivalent stress of 250.76 MPa. Additionally, the maximum displacement of 4.83 mm occurs on the outer ring when subjected to a one-half eccentric load. Concisely, the FEA validates the cutter head’s structural rationality in stiffness and strength. Furthermore, a fatigue durability analysis of the cutter head structure was conducted using nCode DesignLife based on the stress method, determining its fatigue life range to be between 6.857E+4 and 1.253E+7 cycles, with an error not exceeding 20% compared to the theoretical fatigue life. This research provides valuable insights for the structural design and fatigue life studies of cutter heads for TBMs.

When there are adverse conditions such as shallow burial and large bias pressure, half-light and half-darkness, and steep mountains in the tunnel portal section, construction is tough. To ensure the stability of the tunnel opening and the safety of the tunnel construction, according to the geological condition and terrain characteristics, a joint support scheme such as anti-slip piles + retaining wall + anchor cable is proposed; a three -dimensional finite element model is established to analyze the displacement and stress of the surrounding rock and the support structure in the opening section and the support effect is verified by combining with the on-site monitoring data. The results show that: finite element analysis of the Z direction and X direction of the maximum displacement value of 18.7 mm and 20.0 mm are less than the design of the reserved deformation; the maximum tensile and compressive stress of the initial support for 1.2 MPa and 4.0 MPa, respectively, are lower than the initial support of C30 concrete axial tensile and compressive strength design value, indicating that the support force is more reasonable. The cumulative settlement value of the tunnel site monitoring arch top is 16.9 mm. The convergence value of the section periphery is 17.7 mm, which is similar to the value of numerical calculation, indicating that the joint support design can effectively control the displacement of the tunnel surrounding rock and the stress change of the initial support, and the application effect is good.

Ice-rich planets are formed exterior to the water ice-line and thus are expected to contain a substantial amount of ices. The high ice content leads to unique conditions in the interior, under which the structure of a planet is affected by ice interaction with other metals. We apply experimental data of ice-rock interaction at high pressure, and calculate detailed thermal evolution for possible interior configurations of ice-rich planets, in the mass range of super-Earth to Neptunes (5-15 Earth masses). We model the effect of migration inward on the ice-rich interior by including the influences of stellar flux and envelope mass loss. We find that ice and rock are expected to remain mixed, due to miscibility at high pressure, in substantial parts of the planetary interior for billions of years. We also find that the deep interior of planetary twins that have migrated to different distances from the star are usually similar, if no mass loss occurs. Significant mass loss results in separation of the water from the rock on the surface and emergence of a volatile atmosphere of less than 1 percent of the planet's mass. The mass of the atmosphere of water/steam is limited by the ice-rock interaction. We conclude that when ice is abundant in planetary interiors the planet structure may differ significantly from the standard layered structure of a water shell on top of a rocky core. Similar structure is expected in both close-in and further-out planets.

An extension of a previously developed rock physics model is made that quantifies the relationship between the ductile fraction of a brittle/ductile binary mixture and the isotropic seismic reflection response. By making a weak scattering (Born) approximation and plane wave (eikonal) approximation, with a subsequent ordering according to the angle of incidence, singular value decomposition analysis are done to understand the stack weightings, number of stacks, and the type of stacks that will optimally estimate the two fundamental rock physics parameters. Through this angle ordering, it is found that effective wavelets can be used for the stacks up to second order. Finally, it is concluded that the full PP stack and the "full" PS stack are the two optimal stacks needed to estimate the two rock physics parameters. They dominate over both the second order AVO "gradient" stack and the higher order (4th order) PP stack (even at large angles of incidence). Using this result and model based Bayesian inversion, the detectability of the ductile fraction (shown by others to be the important quantity for the geomechanical response of unconventional reservoir fracking) is demonstrated on a model characteristic of the Marcellus shale play.

Video try-on is a challenging task and has not been well tackled in previous works. The main obstacle lies in preserving the details of the clothing and modeling the coherent motions simultaneously. Faced with those difficulties, we address video try-on by proposing a diffusion-based framework named "Tunnel Try-on." The core idea is excavating a "focus tunnel" in the input video that gives close-up shots around the clothing regions. We zoom in on the region in the tunnel to better preserve the fine details of the clothing. To generate coherent motions, we first leverage the Kalman filter to construct smooth crops in the focus tunnel and inject the position embedding of the tunnel into attention layers to improve the continuity of the generated videos. In addition, we develop an environment encoder to extract the context information outside the tunnels as supplementary cues. Equipped with these techniques, Tunnel Try-on keeps the fine details of the clothing and synthesizes stable and smooth videos. Demonstrating significant advancements, Tunnel Try-on could be regarded as the first attempt toward the commercial-level application of virtual try-on in videos.

Traditional Aboriginal Australian cultures include a significant astronomical component, perpetuated through oral tradition and ceremony. This knowledge has practical navigational and calendrical functions, and sometimes extends to a deep understanding of the motion of objects in the sky. Here we explore whether this astronomical tradition is reflected in the rock art of Aboriginal Australians. We find several plausible examples of depictions of astronomical figures and symbols, and also evidence that astronomical observations were used to set out stone arrangements. However, we recognise that the case is not yet strong enough to make an unequivocal statement, and describe our plans for further research.

Antiferromagnetic (AFM) spintronics has emerged as a subfield of spintronics, where an AFM Néel vector is used as a state variable. Efficient electric control and detection of the Néel vector are critical for spintronic applications. This review article features fundamental properties of AFM tunnel junctions (AFMTJs) as spintronic devices where such electric control and detection can be realized. We emphasize critical requirements for observing a large tunneling magnetoresistance (TMR) effect in AFMTJs with collinear and noncollinear AFM electrodes, such as a momentum-dependent spin polarization and Néel spin currents. We further discuss spin torques in AFMTJs that are capable of Néel vector switching. Overall, AFMTJs have potential to become a new standard for spintronics providing larger magnetoresistive effects, few orders of magnitude faster switching speed, and much higher packing density than conventional magnetic tunnel junctions (MTJs).

Driver assistance systems as well as autonomous cars have to rely on sensors to perceive their environment. A heterogeneous set of sensors is used to perform this task robustly. Among them, radar sensors are indispensable because of their range resolution and the possibility to directly measure velocity. Since more and more radar sensors are deployed on the streets, mutual interference must be dealt with. In the so far unregulated automotive radar frequency band, a sensor must be capable of detecting, or even mitigating the harmful effects of interference, which include a decreased detection sensitivity. In this paper, we address this issue with Convolutional Neural Networks (CNNs), which are state-of-the-art machine learning tools. We show that the ability of CNNs to find structured information in data while preserving local information enables superior denoising performance. To achieve this, CNN parameters are found using training with simulated data and integrated into the automotive radar signal processing chain. The presented method is compared with the state of the art, highlighting its promising performance. Hence, CNNs can be employed for interference mitigation as an alternative to conventional signal processing methods. Code and pre-trained models are available at https://github.com/johanna-rock/imRICnn.

Understanding the mechanisms by which cells coordinate their size with their ability to divide has long attracted the interest of biologists. The Target of Rapamycin (TOR) pathway is becoming increasingly recognized as a master regulator of cell size, however less is known how TOR activity might be coupled with the cell cycle. Here, we establish that mTOR complex 1 (mTORC1) promotes cytokinesis through activation of a Rho GTPase-Rho Kinase (ROCK) signaling cascade. Hyperactivation of mTORC1 signaling by depletion of any of its negative regulators: TSC1, TSC2, PTEN, or DEPTOR, induces polyploidy in a rapamycin-sensitive manner. mTORC1 hyperactivation-mediated polyploidization occurs by a prolonged, but ultimately failed attempt at abcission followed by re-fusion. Similar to the effects of ROCK2 overexpression, these mTORC1-driven aberrant cytokinesis events are accompanied by increased Rho-GTP loading, extensive plasma membrane blebbing, and increased actin-myosin contractility, all of which can be rescued by either mTORC1 or ROCK inhibition. These results provide evidence for the existence of a novel mTORC1-Rho-ROCK pathway during cytokinesis and suggest that mTORC1 might play a critical role in setting the size at which a mammalian cell divides.

This paper presents a modified grand canonical ensemble which provides a new simple and efficient scheme to study few-body fluid-like inhomogeneous systems under confinement. The new formalism is implemented to investigate the exact thermodynamic properties of a hard sphere (HS) fluid-like system with up to three particles confined in a spherical cavity. In addition, the partition function of this system was used to analyze the surface thermodynamic properties of the many-HS system and to derive the exact curvature dependence of both the surface tension and adsorption in powers of the density. The expressions for the surface tension and the adsorption were also obtained for the many- HS system outside of a fixed hard spherical object. We used these results to derive the dependence of the fluid-substrate Tolman length up to first order in density.

Predicting the geometrical evolution of the pore space in geological formations due to fluid-solid interactions has applications in reservoir engineering, oil recovery, and geological storage of carbon dioxide. However, modeling frameworks that combine fluid flow with physical and chemical processes at a rock's pore scale are scarce. Here, we report a method for modeling a rock's pore space as a network of connected capillaries and to simulate the capillary diameter modifications caused by reactive flow processes. Specifically, we model mineral erosion, deposition, dissolution, and precipitation processes by solving the transport equations iteratively, computing diameter changes within each capillary of the network simultaneously. Our automated modeling framework enables simulations on digital rock samples as large as (1.125mm)$^3$ with 125$\times 10^6$ voxels within seconds of CPU time per iteration. As an application of the computational method, we have simulated brine injection and calcium carbonate precipitation in sandstone. For quantitatively comparing simulation results obtained with models predicting either a constant or a flow-rate dependent precipitation, we track the time-dependent capillary diameter distribution as well as the permeability of the connected pore space. For validation and reuse, we have made the automated simulation workflow, the reactive flow model library, and the digital rock samples available in public repositories.

An overview of some analytical approaches to the computation of the structural and thermodynamic properties of single component and multicomponent hard-sphere fluids is provided. For the structural properties, they yield a thermodynamically consistent formulation, thus improving and extending the known analytical results of the Percus-Yevick theory. Approximate expressions for the contact values of the radial distribution functions and the corresponding analytical equations of state are also discussed. Extensions of this methodology to related systems, such as sticky hard spheres and square-well fluids, as well as its use in connection with the perturbation theory of fluids are briefly addressed.

The igneous rocks in deep formation have the characteristics of hardness, poor drillability and high abrasiveness, which is a difficulty in speeding up drilling. The drilling efficiency of existing conventional bits is low in igneous rocks. Based on the characteristics of igneous rocks, rock mechanical parameters and drillability experiments of granite, sandstone and other rocks were carried out. The rock drilling experiments of composite bit, tri-cone bit and PDC bit were carried out. Experiments have shown that in granite with very high strength, the drilling efficiency of conventional cone bit is very low, and it is extremely difficult for PDC bit to penetrate. The impact crushing effect of the cone of the composite bit can make the rock at the bottom of the well produce pits and cracks, which can assist the PDC cutters to penetrate into the formation, and solve the problem of the PDC cutters difficulty in penetrating in hard formations. In softer formations, the rock-breaking advantage of composite bit is not obvious, and the rock-breaking efficiency is lower than that of PDC bit. However, in hard formations, the advantage of composite bit is obvious, with higher drilling efficiency than PDC bit and cone bits. The personalized composite bit developed for deep igneous rocks formations has fast drilling speed, strong sustained drilling ability, long footage, and significant drilling speed-up effect. It significantly reduces the number of runs in deep drilling operations and achieves good application results. The composite bit is suitable for drilling in deep igneous hard-to-drill formations, and it has obvious advantages in deep igneous formations. It is a good choice for drilling speed-up in this kind of hard-to-drill formation.

Computer science research has led to many breakthrough innovations but has also been scrutinized for enabling technology that has negative, unintended consequences for society. Given the increasing discussions of ethics in the news and among researchers, we interviewed 20 researchers in various CS sub-disciplines to identify whether and how they consider potential unintended consequences of their research innovations. We show that considering unintended consequences is generally seen as important but rarely practiced. Principal barriers are a lack of formal process and strategy as well as the academic practice that prioritizes fast progress and publications. Drawing on these findings, we discuss approaches to support researchers in routinely considering unintended consequences, from bringing diverse perspectives through community participation to increasing incentives to investigate potential consequences. We intend for our work to pave the way for routine explorations of the societal implications of technological innovations before, during, and after the research process.

We present a new theory which describes the collection of all tunnels of tunnel number 1 knots in the 3-sphere (up to orientation-preserving equivalence in the sense of Heegaard splittings) using the disk complex of the genus-2 handlebody and associated structures. It shows that each knot tunnel is obtained from the tunnel of the trivial knot by a uniquely determined sequence of simple cabling constructions. A cabling construction is determined by a single rational parameter, so there is a corresponding numerical parameterization of all tunnels by sequences of such parameters and some additional data. Up to superficial differences in definition, the final parameter of this sequence is the Scharlemann-Thompson invariant of the tunnel, and the other parameters are the Scharlemann-Thompson invariants of the intermediate tunnels produced by the constructions. We calculate the parameter sequences for tunnels of 2-bridge knots. The theory extends easily to links, and to allow equivalence of tunnels by homeomorphisms that may be orientation-reversing.

Dynamic surface reconstruction of objects from point cloud sequences is a challenging field in computer graphics. Existing approaches either require multiple regularization terms or extensive training data which, however, lead to compromises in reconstruction accuracy as well as over-smoothing or poor generalization to unseen objects and motions. To address these lim- itations, we introduce Preconditioned Deformation Grids, a novel technique for estimating coherent deformation fields directly from unstructured point cloud sequences without requiring or forming explicit correspondences. Key to our approach is the use of multi-resolution voxel grids that capture the overall motion at varying spatial scales, enabling a more flexible deformation representation. In conjunction with incorporating grid-based Sobolev preconditioning into gradient-based optimization, we show that applying a Chamfer loss between the input point clouds as well as to an evolving template mesh is sufficient to obtain accurate deformations. To ensure temporal consistency along the object surface, we include a weak isometry loss on mesh edges which complements the main objective without constraining deformation fidelity. Extensive evaluations demonstrate that our method achieves superior results, particularly for long sequences, compared to state-of-the-art techniques.

We introduce a novel regularization for localizing an elastic-energy-driven deformation to only those regions being manipulated by the user. Our local deformation features a natural region of influence, which is automatically adaptive to the geometry of the shape, the size of the deformation and the elastic energy in use. We further propose a three-block ADMM-based optimization to efficiently minimize the energy and achieve interactive frame rates. Our approach avoids the artifacts of other alternative methods, is simple and easy to implement, does not require tedious control primitive setup and generalizes across different dimensions and elastic energies. We demonstrates the effectiveness and efficiency of our localized deformation tool through a variety of local editing scenarios, including 1D, 2D, 3D elasticity and cloth deformation.

For a genus-1 1-bridge knot in the 3-sphere, that is, a (1,1)-knot, a middle tunnel is a tunnel that is not an upper or lower tunnel for some (1,1)-position. Most torus knots have a middle tunnel, and non-torus-knot examples were obtained by Goda, Hayashi, and Ishihara. In a previous paper, we generalized their construction and calculated the slope invariants for the resulting examples. We give an iterated version of the construction that produces many more examples, and calculate their slope invariants. If one starts with the trivial knot, the iterated constructions produce all the 2-bridge knots, giving a new calculation of the slope invariants of their tunnels. In the final section we compile a list of the known possibilities for the set of tunnels of a given tunnel number 1 knot.

The description of the initial state of heavy ion collisions, which covers the description of the incoming nuclei, the initial hard and soft interactions, the resulting spatial geometry of the produced matter, as well as the dynamic approach to a medium well described by hydrodynamics, has important consequences for the study of hard and electromagnetic probes. I will review new developments presented at Hard Probes 2020 that have an impact on these aspects of our understanding of the initial state of heavy ion and smaller system collisions.

Hard-jet correlations probe parton energy loss and the microscopic structure of the quark-gluon plasma formed in ultra-relativistic heavy-ion collisions. The correlation of high-$p_\mathrm{T}$ jets with other jets, hadrons, or electroweak bosons, offers differential sensitivity to medium-induced effects such as momentum broadening, color decoherence, and medium response in different types of nuclear reactions. Such correlations can also be used to study cold nuclear matter effects arising in $p$+A collisions. This proceeding summarizes recent advances achieved by studying hard-jet correlations in large and small systems discussed at Hard Probes 2024, complementing the experimental jet overview.

This paper is the continuation of arXiv:0802.1245. We construct the Hochschild class for coherent modules over a deformation quantization algebroid on a complex Poisson manifold. We also define the convolution of Hochschild homologies, and prove that the Hochschild class of the convolution of two coherent modules is the convolution of their Hochschild classes. We study with some details the case of symplectic deformations.

In this paper we address the following question: is it always possible to choose a deformation quantization of a Poisson algebra A so that certain Poisson-commutative subalgebra C in it remains commutative? We define a series of cohomological obstructions to this, that take values in the Hochschild cohomology of C with coefficients in A. In some particular case of the pair (A,C) we reduce these classes to the classes of the Poisson relative cohomology of the Hochschild cohomology. We show, that in the case, when the algebra C is polynomial, these obstructions coincide with the previously known ones, those which were defined by Garay and van Straten.

This article presents novel designs of autonomous UAV prototypes specifically developed for inspecting GPS-denied tunnel construction environments with dynamic human and robotic presence. Our UAVs integrate advanced sensor suites and robust motion planning algorithms to autonomously navigate and explore these complex environments. We validated our approach through comprehensive simulation experiments in PX4 Gazebo and Airsim Unreal Engine 4 environments. Real-world wind tests and exploration experiments demonstrate the UAVs' capability to operate stably under diverse environmental conditions without GPS assistance. This study highlights the practicality and resilience of our UAV prototypes in real-world applications.

Here we survey the compactness and geometric stability conjectures formulated by the participants at the 2018 IAS Emerging Topics Workshop on {\em Scalar Curvature and Convergence}. We have tried to survey all the progress towards these conjectures as well as related examples, although it is impossible to cover everything. We focus primarily on sequences of compact Riemannian manifolds with nonnegative scalar curvature and their limit spaces. Christina Sormani is grateful to have had the opportunity to write up our ideas and has done her best to credit everyone involved within the paper even though she is the only author listed above. In truth we are a team of over thirty people working together and apart on these deep questions and we welcome everyone who is interested in these conjectures to join us.

These notes were compiled as lecture notes for a course developed and taught at the University of the Southern California. They should be accessible to a typical engineering graduate student with a strong background in Applied Mathematics. The main objective of these notes is to introduce a student who is familiar with concepts in linear algebra and partial differential equations to select topics in deep learning. These lecture notes exploit the strong connections between deep learning algorithms and the more conventional techniques of computational physics to achieve two goals. First, they use concepts from computational physics to develop an understanding of deep learning algorithms. Not surprisingly, many concepts in deep learning can be connected to similar concepts in computational physics, and one can utilize this connection to better understand these algorithms. Second, several novel deep learning algorithms can be used to solve challenging problems in computational physics. Thus, they offer someone who is interested in modeling a physical phenomena with a complementary set of tools.

Deep Neural Networks, often owing to the overparameterization, are shown to be capable of exactly memorizing even randomly labelled data. Empirical studies have also shown that none of the standard regularization techniques mitigate such overfitting. We investigate whether the choice of the loss function can affect this memorization. We empirically show, with benchmark data sets MNIST and CIFAR-10, that a symmetric loss function, as opposed to either cross-entropy or squared error loss, results in significant improvement in the ability of the network to resist such overfitting. We then provide a formal definition for robustness to memorization and provide a theoretical explanation as to why the symmetric losses provide this robustness. Our results clearly bring out the role loss functions alone can play in this phenomenon of memorization.

Deep neural networks and the ENO procedure are both efficient frameworks for approximating rough functions. We prove that at any order, the ENO interpolation procedure can be cast as a deep ReLU neural network. This surprising fact enables the transfer of several desirable properties of the ENO procedure to deep neural networks, including its high-order accuracy at approximating Lipschitz functions. Numerical tests for the resulting neural networks show excellent performance for approximating solutions of nonlinear conservation laws and at data compression.

Evidential deep learning, built upon belief theory and subjective logic, offers a principled and computationally efficient way to turn a deterministic neural network uncertainty-aware. The resultant evidential models can quantify fine-grained uncertainty using the learned evidence. To ensure theoretically sound evidential models, the evidence needs to be non-negative, which requires special activation functions for model training and inference. This constraint often leads to inferior predictive performance compared to standard softmax models, making it challenging to extend them to many large-scale datasets. To unveil the real cause of this undesired behavior, we theoretically investigate evidential models and identify a fundamental limitation that explains the inferior performance: existing evidential activation functions create zero evidence regions, which prevent the model to learn from training samples falling into such regions. A deeper analysis of evidential activation functions based on our theoretical underpinning inspires the design of a novel regularizer that effectively alleviates this fundamental limitation. Extensive experiments over many challenging real-world datasets and settings confirm our theoretical findings and demonstrate the effectiveness of our proposed approach.

Evidential deep learning (EDL) models, based on Subjective Logic, introduce a principled and computationally efficient way to make deterministic neural networks uncertainty-aware. The resulting evidential models can quantify fine-grained uncertainty using learned evidence. However, the Subjective-Logic framework constrains evidence to be non-negative, requiring specific activation functions whose geometric properties can induce activation-dependent learning-freeze behavior: a regime where gradients become extremely small for samples mapped into low-evidence regions. We theoretically characterize this behavior and analyze how different evidential activations influence learning dynamics. Building on this analysis, we design a general family of activation functions and corresponding evidential regularizers that provide an alternative pathway for consistent evidence updates across activation regimes. Extensive experiments on four benchmark classification problems (MNIST, CIFAR-10, CIFAR-100, and Tiny-ImageNet), two few-shot classification problems, and blind face restoration problem empirically validate the developed theory and demonstrate the effectiveness of the proposed generalized regularized evidential models.