The time-dependent failure of surrounding rock in deep engineering is essentially controlled by the evolution of microcracks, with the pre-existing fracturing state induced by excavation playing a crucial role in the subsequent time-dependent fracturing process. From the perspective of microcrack development, it is a continuous, dynamic process. Therefore, taking the microcrack propagation process as the fundamental principle, this paper proposes a novel three-dimensional (3D) time-dependent model for hard rock that can depict the entire fracturing process within a unified theoretical framework. This developed model discards the traditional tri-modal partition method based on deformation, and instead adopts an analysis approach centred on time-dependent tensile and shear fracturing. The results show that the time-dependent deformation of hard rock is the macroscopic manifestation of the progressive evolution of microcracks over time. Under true triaxial stress, the growth tendency of cracks in hard rock is orientation-dependent throughout the entire loading process. This developed model provides a mechanical explanation for key time-dependent fracture characteristics observed in true triaxial creep tests, including the anisotropy of time-dependent deformation and the preferred orientation of macroscopic failure plane, and provides a novel framework for elucidating the time-dependent failure process of hard rock.

Sub-level caving (SLC) is a mass mining method suitable for large, steeply dipping orebodies. The particle size distribution (PSD) of blasted material affects material flow through the stope. Improving blast-induced fragmentation can enhance draw point extraction, increasing ore recovery, reducing dilution, and lowering costs in loading and crushing. Numerical simulations using the Mechanistic Blasting Model (MBM) explored these improvements. MBM simulates the explosive loading, rock fracturing, and dynamic explosive gas effects. It addresses uneven explosive distribution from fan-shaped blast holes and complex broken ground conditions. The simulations used Ernest Henry Mine (EHM) data to define the baseline blast design and rock mass and compared field and modelled fragmentation sizes for varying explosive densities and burden sizes. Then, MBM simulations incorporated different rock mass fracture densities, tensile strengths and in-situ stresses, and further blast design changes in the blasthole diameter and charge spacings. A total of 34 scenarios were modelled. Multivariate regression analysis identified key parameters, and new regression models for P20, P50, and P80 passing sizes were developed and validated against the EHM and MBM simulation data. Additional simulations confirmed that while regression predictive models were slightly less accurate, they provided efficient predictions with acceptable accuracy.

This study presents a novel framework for evaluating slope stability in spatially variable soils by integrating a newly developed sequential limit analysis based on the Hellinger-Reissner functional, utilizing the node-based smoothed finite element method (NS-FEM), with a newly proposed deep learning (DL) approach termed multi-downsampling hybrid Linformer-convolutional neural networks (CNNs). The NS-FEM-based mixed formulation of limit analysis (MFLA) enhances computational accuracy and convergence by smoothing strain fields and mitigating numerical discontinuities commonly encountered in standard finite element methods (FEMs). This method generates reliable datasets for stochastic simulations of slope stability under both static and seismic loading conditions. To address the computational expense of specific simulations, we propose the multi-downsampling hybrid Linformer-CNN model, a sophisticated DL architecture that employs dual parallel pathways with distinct downsampling strategies - AveragePpooling1D for medium-scale feature extraction and MaxPooling1D for coarse-scale feature extraction. Each pathway integrates one-dimensional (1D) CNNs for local feature extraction and Linformer-based self-attention mechanisms to efficiently capture global dependencies. The parallel downsampling strategies balance computational efficiency with feature granularity, enabling the model to leverage both local and global data characteristics effectively. The extracted multi-scale features are concatenated and further processed through fully connected networks (FCNs) to accurately predict the factor of safety (FoS) of slopes. Comparative analyses demonstrate that the hybrid Linformer-CNN model outperforms traditional FCN and CNN architectures, achieving robust and precise predictions with a mean absolute percentage error (MAPE) below 10 %. Additionally, the proposed framework significantly reduces computational time, highlighting the potential of integrating NS-FEM-based MFLA with advanced DL architectures for rapid and reliable slope stability assessment in geotechnical engineering.

This study investigates the influence of mean stress and Lode angle on the mechanical behavior of porous sandstone. Sandstone specimens were tested using a newly developed true-triaxial loading apparatus under five constant Lode angle conditions and seven different mean stresses, covering a transition from brittle to ductile regimes. Based on the experimental results, three types of stress-strain responses were identified, transitioning progressively from Type 1, through Type 2 to Type 3 as the mean stress increases. Type 1 response represents typical brittle behavior, characterized by prominent shear fractures. Type 2 response corresponds to the brittle-ductile transition behavior, exhibiting non-penetrating shear fractures. Type 3 response is associated with ductile behavior, characterized by no visible shear fractures. The deviatoric stress initially increases and then decreases with increasing mean stress, forming a cap surface in the meridian plane. A generalized failure criterion is subsequently developed, capable of accurately characterizing this strength response. Furthermore, the brittle-ductile transition behavior is found to be significantly dependent on the Lode angle. Finally, the brittle-ductile transition boundary is described, incorporating the dependence of Lode angle.

Cemented paste backfill (CPB) is a key material in underground mining, providing essential ground support while aiding in tailings management. However, current research has overlooked the combined effects of horizontal rockwall closure stress and vertical self-loading stress, referred to as multiaxial stress, on the CPB's consolidation behavior and its mechanical properties development. Understanding and assessing these effects is critical because they directly affect the stability and performance of CPB structures. In this study, a novel multiaxial compressive stress curing and monitoring apparatus was used to simulate two horizontal rockwall closure scenarios with a consistent backfilling rate, under both drained and undrained conditions. Key parameters assessed included unconfined compressive strength (UCS), deformation during curing, stress-strain behavior, and modulus of elasticity. The results highlight that rockwall closure, combined with vertical stress, plays a pivotal role in the consolidation behavior of CPB, significantly affecting key mechanical properties. Higher horizontal stress from faster rockwall closure intensified compression during curing, leading to reduced porosity, enhanced particle rearrangement, and accelerated consolidation. This intensified consolidation leads to notable improvements in mechanical properties, including increased UCS, enhanced stiffness, and a higher modulus of elasticity, indicating improved load-bearing capacity. Moreover, the interaction between multiaxial stress and drainage conditions influenced stress-strain behavior and deformation, with drained conditions promoting earlier plasticity and higher peak stresses. These findings underscore the critical influence of multiaxial stress, combined with drainage conditions, on CPB performance, offering valuable insights for optimizing CPB design in underground mining applications.

This study integrates unconfined compression tests with high-resolution computed tomography (CT) to analyze the pore heterogeneity, crack propagation, and failure modes of red sandstone specimens with diameters ranging from 10 mm to 100 mm. Key findings include: (1) With increasing specimen size, crack initiation stress (CI), damage stress (CD), and unconfined compressive strength (UCS) initially increase and then decrease, (2) In smaller specimens, stress concentration due to pore heterogeneity leads to splitting failure and lower strength, (3) In medium-sized specimens, friction dominates crack propagation, causing shear failure, while increased fragment rotation enhances energy dissipation, yielding highest strength, and (4) In larger specimens, cracks tend to propagate along bedding planes, reducing energy dissipation and then weakening strength. These results provide insights into the reverse size effect on sandstone strength and have implications for engineering applications.

Liquid nitrogen (LN₂)-assisted fracturing has emerged as a promising technique to enhance the productivity of hot dry rock (HDR) geothermal reservoirs. To elucidate the progressive mechanical degradation and fracture mechanisms of granite under cyclic thermal shocks, this study integrates ultrasonic testing, acoustic emission (AE) monitoring, three-dimensional profilometry, and uniaxial compression testing. Damage evolution was assessed through velocity attenuation, waveform distortion, and AE characteristics, while microcrack propagation and fracture morphology were analyzed using scanning electron microscopy and surface topography reconstruction. The degradation process exhibits a distinct cycle-dependent transition, evolving from tensile microcrack initiation during early cycles to shear-dominated failure during prolonged cycling. In Phase Ⅰ (1-3 cycles), initial thermal stresses induce axial tensile microcracks, leading to sharp decreases in P-wave velocity (53.45 %) and amplitude (40.55 %). Frequency analysis reveals a narrowing and convergence of secondary bands, whereas the fracture surfaces exhibit low undulation, dominated by tensile failure. In Phase II (3-20 cycles), shear-dominated damage progressively develops, as cyclic cooling enhances crack connectivity. AE activity intensifies sharply, correlating with macroscopic shear crack networks. Fracture surfaces evolve toward step-like morphologies, with roughness parameters increasing by up to 277.43 %, indicative of composite tensile-shear failure. Cyclic LN₂ cooling significantly lowers crack initiation stress and fracture energy, while promoting crack density and surface roughness. These findings provide critical insights into the mechanisms of LN₂-induced fracture enhancement, highlighting its potential to optimize HDR reservoir stimulation strategies.

Current in-situ stress determination methods are typically conducted inside a drillhole after its creation. However, the drilling process itself is not utilized for measuring in-situ stress or rock strength, despite being a form of direct mechanical testing on the rock mass. Crucially, drilling contains valuable information about in-situ stress and rock strength, as rocks under high compressive stresses exhibit greater strength. This paper presents a novel in-situ stress determination method, supported by the experimental result of rock drilling monitoring tests using a mine hydraulic-rotary drilling machine. Key drilling parameters-including thrust force, rotation speed, torque and drilling speed-are monitored in real time to determine the drilling specific energy per unit volume of rock. A concave-upward relationship between drilling specific energy and rotation speed is identified, which can characterize rock compressive strength and tensile strength with consistent regularity. Further drilling tests are conducted on the same rock samples under varying confining pressures. Results indicate that as confining pressure increases, the concave-upward curve of drilling specific energy shift upward, reflecting enhanced rock strengths due to confinement. The paper outlines the complete methodology for in-situ stress determination using drilling monitoring techniques, bridging the research gaps among drilling monitoring, rock mechanics, and in-situ stress analysis.

The instability of composite coal-rock structures can easily trigger severe dynamic disasters, such as rockbursts. The application of electric potential (EP) method shows promise for disaster prediction and accurate identification of coal-rock interfaces. In this study, uniaxial compression experiments were conducted to monitor the EP spatiotemporal response of fine sandstone-coal and coarse sandstone-coal combined samples. EP distribution contour maps and three-dimensional (3D) EP models were utilized to explore the failure mechanisms and identify the interface state. Then the relationship between EP response and force field was examined through numerical simulations. An EP-based multifractal method was utilized to predict rock failure. Results show that the intensity and polarity of EPs differ between coal and rock but are correlated with stress state. The progressive failure features of two types of combined samples differ, triggering distinct EP responses. In the EP contour maps, the EP level increases with increasing height, and a low-intensity signal band appears around the interface before failure. When failure occurs, the EP field changes, and the low-intensity signal band becomes distorted. The 3D EP models effectively visualize the progressive failure of combined samples and clearly identify the interface location, similar to acoustic emission (AE) location. The evolution of force chain field is closely related to EP generation, and sparse strong force chain fields leads to a significant increase in EP level. Furthermore, the EPs display multifractal features, with precursory information being reflected inΔα and Δf. This study provides new ideas for early-warning of composite coal-rock and coal-rock interface identification.

The ISRM-suggested Brazilian disc (BD) test using split Hopkinson pressure bar (SHPB) for dynamic rock tensile strength requires central crack initiation and stress equilibrium. This study aims to re-evaluate the critical strain rate, ensuring a valid dynamic Brazilian disc test, and to analyse the reliable dynamic tensile behaviour of granite using high-speed digital image correlation (DIC). The comparison between the measured strain obtained through high-speed DIC analysis and the strain gauge allowed for determining the optimal subset parameters used to obtain the real-time deformation field and the stress-strain curve from DIC data. Crack initiation, crack velocity, and failure process are studied to reveal the rate dependence of granites. A unified dynamic increase factor (DIF) model is proposed for the tensile strength of rocks, and the reason for the sudden drop in DIF for high strain rates is discussed. The results reveal that the upper limit of the valid strain rate, which ensures the validity of the ISRM-suggested dynamic BD test, is co-determined by the conditions of stress equilibrium and crack initiation from the centre of the disc. At higher strain rates (75 s^-1), BD test results fail to capture the actual tensile behaviour of rocks, and the potential factors influencing the critical valid strain rate (CVSr), such as sample radius and boundary crack length, should also be considered.

Investigating the mechanical behavior and microstructural evolution of granite under high temperatures is crucial for optimizing fracturing strategies and ensuring reservoir sustainability in enhanced geothermal systems (EGS) at the Qiabuqia geothermal field, China. This study conducted triaxial compression tests on granite from the Qinghai Gonghe Basin under temperature from 25 ℃ to 300 ℃, examining the effects of temperature and confining pressure on the mechanical properties and energy evolution of the granite. Additionally, X-ray diffraction (XRD) analysis and nanoindentation tests were employed to assess changes in micro-mechanical properties and mineral compositions. Furthermore, fracture mechanics principles, incorporating thermal stress effects, were utilized to calculate the initiation pressure of reservoirs at an engineering scale for geothermal development in the Qinghai Gonghe Basin. The results indicate that the compressive strength and elastic modulus of Gonghe granite increase with temperature up to 200 ℃ due to the enhancement of mineral mechanical properties and thermal densification, but significantly decrease at 300 ℃ due to thermal damage and fracture propagation. Energy analysis reveals that the granite undergoes a transition from brittle to ductile behavior under high-temperature conditions. The proportion of energy dissipation during deformation increases with temperature. The increased proportion of quartz, coupled with its high thermal expansion coefficient and elastic modulus, generates intense thermal stress at the interfaces between quartz and adjacent minerals. The development and propagation of transgranular fractures around quartz are critical factors influencing the macroscopic mechanical properties of granite. This study provides a good understanding of the effects of high temperature on granite performance and its engineering significance in reservoir development, emphasizing the role of thermal stress in reducing fracturing pressure and promoting fracture propagation.

The strain energy storage index (W_ET) is a crucial index for evaluating rockburst proneness. Interestingly, when conducting tests to obtain W_ET, variations exist in the shape of coal or rock specimens. However, whether shape factors affect W_ET has not been theoretically and experimentally verified. In this study, to investigate the independence of W_ET from specimen shape effects, its rationality was first theoretically derived based on the linear energy storage (LES) laws of rock, indicating that W_ET is influenced by the energy storage coefficient (ESC) of the rock. Two typical rock materials (granite and red sandstone) with different rockburst proneness were selected to verify the migration effect of cubic and cylindrical specimens on W_ET via uniaxial compression tests. The experimental results revealed that the mechanical behavior characteristics of rocks were affected by the shape of cylindrical and cubic specimens, whereas the W_ET and ESC were opposite. Furthermore, the practical W_ET values closely approximate the theoretical values of energy storage-dissipated ratio predicted by the LES law, converging to the peak-strength strain energy storage index (). Based on the LES law, the influence of specimen shape on W_ET and was further discussed, concluding that W_ET and are independent of specimen shape effects. Furthermore, the is more stable than W_ET and reflects the relative magnitude of energy storage and dissipation during the entire pre-peak of rock. Thus, the peak-strength strain energy storage index can be used as a substitute for W_ET in evaluating the rockburst proneness of rock.

The phase-field method (PFM) has emerged as a robust tool for fracture simulation; however, applying this technique to rock materials poses significant challenges, particularly in accurately modeling the propagation of multiple cracks in the presence of complex three-dimensional (3D) mixed-mode loading involving tensile, tensile-shear, and compressive-shear cracks. To address these limitations, this study aims to introduce an enhanced PFM that integrates frictional effects and Lode angle dependence while unifying the volumetric deviatoric (VD) and spectral decomposition (SD) methods. The proposed model incorporates a modified driving force for 3D compressive-shear cracks by embedding a triple shear energy strength (TSES) criterion within the energy decomposition framework. This refinement guarantees that crack behavior remains physically realistic under compression-dominated loading while effectively preserving well-established tensile fracture mechanisms. The validation of the numerical implementation is also conducted through both analytical verification against theoretical solutions and 3D finite element simulations of fissured rock and heterogeneous specimens. Furthermore, numerical case studies demonstrate the model's ability to effectively capture the 3D propagation of multiple cracks and replicate realistic true 3D mechanical responses. The findings present valuable insights and practical guidelines for the application of PFM in rock engineering.

Soil erosion induced by rainfall on slopes poses a significant threat to land sustainability and ecological balance. Enzyme-induced calcium carbonate precipitation (EICP), as an emerging environmentally friendly biomineralization technology, can form a stable crust layer on slopes, effectively reducing rainwater infiltration and enhancing soil erosion resistance. This study designed rainfall erosion model tank tests using soybean urease and cementation solution. The treatment effects were evaluated through macro and microscopic indicators, and the hydrological response of the slope under different rainfall conditions was analysed. The results indicate the calcium carbonate content (CCC) and crust thickness of the slope gradually increase while tend to saturate with treatments. The slope gradient exhibits a controlling influence on the crust distribution, with a systematic downslope shift in the peak thickness zone as the gradient increases. At the microscopic level, with the increase of treatment cycles, the pore volume is significantly reduced, and the particle surface is extensively coated with CaCO₃ precipitates. From a geomorphological perspective, untreated slopes develop rapid and deep gully networks, while treated slopes transition to smoother and more stable surfaces. Under high rainfall intensity, the erosion amount for the slope with ten cycles of treatment reduced significantly, and the maximum gully width and depth exhibit a decreasing trend with erosion amount. The surface runoff rate reaches the optimal performance after seven cycles of treatment, where a continuous uniform CaCO₃ crust significantly increases the runoff rate. The relationship for erosion, runoff rate, and infiltration coefficient with more treatments reflects a coordinated trend.

Hazardous geophysical granular flows, such as debris flows and rock avalanches, can exert intense impact forces on obstacles and threaten downstream structures located in their paths. Installing protective structures can mitigate damage, but quantifying their influence on flow evolution and impact loading remains challenging. This study investigates the interactions of granular shock waves (GSWs) generated in front of two cylindrical obstacles with varying spacings through chute experiments and discrete element modeling. Impact pressure sensors were mounted on the upstream surface of each cylinder and on the chute bed to measure dynamic impact pressures in the GSW region. Granular flow velocity and depth were obtained using image processing. Results demonstrate that cylinder spacing significantly influences the geometric characteristics of GSWs. Runup increases with steady-state Froude number (Fr_steady) but decreases as spacing narrows. The granular vacuum length grows with bed slope but decreases significantly with decreasing cylinder spacing. Impact pressures on the cylinders and the chute bed increase linearly with Fr_steady. Low-frequency power spectral density (PSD) is positively correlated with Fr_steady, whereas centroid frequency and pressure impulse counts exhibit low sensitivity to Fr_steady. The dimensionless impact pressure coefficient (α) decreases nonlinearly with increasing Froude number (Fr). At low Fr, α values for dry granular flows are lower than those for debris flows, but the difference diminishes at higher Fr. These findings may improve our understanding of granular flow-obstacle interactions and might help to design protective structures.

During geotechnical construction, flawed rock masses experience dynamic cyclic disturbances, leading to cumulative deformation and progressive damage. Consequently, elucidating the fracture mechanisms under cyclic loading is crucial for ensuring the safety and prolonged operation of deep underground engineering. This study investigated the mechanical responses of the surrounding rock at different locations by conducting triaxial tests on flawed granite using three distinct cyclic loading and unloading paths. Based on the maximum tangential stress criterion, a fracture mechanics model for open flaws was developed to analyze the intrinsic influence of confining pressure and flaw inclination on crack initiation behavior. The results indicate that graded unloading of confining pressure significantly weakens the flawed rock mass, reducing its peak stress to only 77.5 % of that observed under constant confining pressure. Conversely, flawed rock masses exhibit a substantial increase in bearing capacity under increasing graded cyclic loading, achieving a peak stress 19.3 % higher than that under cyclic disturbance loading. At a constant confining pressure of 40 MPa, the type of disturbance loading has no significant effect on the failure mode. The flawed granite specimens form a nearly V-shaped shear failure zone along the open flaw. However, confining pressure unloading induced a more complex shear-tensile composite failure mode in the specimens. The crack initiation angle increases nonlinearly with confining pressure, but decreases gradually as the flaw inclination angle (β) increases. These findings provide valuable insights for the safe construction of deep underground engineering.

Borehole instability in heterogeneous rocks poses a significant challenge in geo-energy engineering. The deformation and failure around boreholes are heavily mediated by the inherent heterogeneity of rocks. Here, we examined borehole breakout under hydrostatic pressure through both laboratory tests and numerical simulations on sandstone samples. Laboratory experiments demonstrated symmetrical V-shaped failures across various borehole diameters. To replicate these observations, we developed a heterogenous UDEC Voronoi model where the material heterogeneity was interpreted by assigning Weibull-distributed inter-grain contact parameters. The rigorous-calibrated numerical modeling can effectively capture the microscopic damage process and match the observed macroscopic failure modes. Simulations showed that reducing the borehole diameter increases the critical hydrostatic pressure required for borehole failure and prompts a shift from tensile to shear-dominated failure behavior. While stress anisotropy primarily governs the overall breakout morphology, rock heterogeneity influences the specific locations of crack initiation, leading to localized stress concentrations that shape the ultimate failure patterns. These results provide valuable insights into borehole stability in heterogeneous rocks and guide engineering design and pertinent risk assessment.

Evaluation of compressive strength in underground lining structures is critical for ensuring structural integrity and safety. Traditional assessment methods are often destructive, time-consuming, and impractical in confined environments such as tunnels and utility corridors. This study introduces an automated, nondestructive approach to visualize and estimate the compressive strength of underground concrete lining using hyperspectral imaging (HSI) combined with deep neural network (DNN) models. High-dimensional spectral data of concrete lining are assembled and trained to develop two DNN-based regression models, namely the Mono-Spectrum Deep Neural Regressor (MS-DNR) and the Segmented-Spectrum Deep Neural Regressor (SegS_DNR). Utilizing the SegS_DNR model, two-dimensional (2D) compressive strength distribution heatmaps were generated for visualization and assessment of strength variations. The SegS_DNR model demonstrated excellent predictive performance, achieving a coefficient of determination () of 0.925 and a Residual Prediction Deviation (RPD) of 5.28 on the testing set for compressive strength estimation. The idea is further validated in site by investigating the capability of identifying the defect regions of the tunnel concrete lining, namely the cracked, spalling, and leaking areas, and demonstrated promising performance in comparison with experienced inspectors on site. This approach offers a contact-free technique for automated structural health monitoring, contributing to safer and more sustainable underground maintenance practices.

During unconventional energy extraction, substantial volumes of fluid are injected into low-permeability reservoirs to facilitate hydraulic fracturing, creating an extensive network of fractures that enhance fluid mobility. However, such large-scale fluid injection can lead to the initiation and propagation of fractures, potentially triggering detectable seismic events that pose risks to human life and infrastructure. To better understand these processes, in situ dynamic scanning imaging of hydraulic fracture propagation and water-rock interactions in tight sandstones has been conducted using X-ray computed tomography (CT). Our experimental findings reveal that fluid infiltration weakens rock strength, thereby promoting rock failure. Under the influence of fluid injection, microfractures undergo a continuous cycle of generation, expansion, and coalescence, ultimately forming interconnected hydrological pathways. These pathways are critical for the sustained propagation of fractures within the rock. CT imaging highlights a positive feedback loop between fracture growth and the enhancement of fluid diffusion. Notably, the rock at the dry-wet interface of the fluid front is particularly susceptible to fracturing. Additionally, the rates of fracturing vary among different fractures and tend to progressively decrease as the fractures extend deeper into the rock.

Thermal cycling and stress fatigue are recognized as principal factors that induce the Kaiser effect of rock in deep earth rock engineering. Nevertheless, existing scholarly investigations about the mechanical properties of rocks subjected to the synergistic effects of these perturbations have remained insufficient. In this study, conventional triaxial compression tests, multistage equal-amplitude fatigue (MEF) and multistage variable-amplitude fatigue (MVF) tests were conducted on marble subjected to different numbers of thermal cycles, integrated with nuclear magnetic resonance (NMR) and depth-sensing indentation (DSI) micro-monitoring methods, and the rock constitutive equation was established from the perspective of statistical microscopic damage. The results indicated that the increasing number of thermal cycles significantly weakened the physical and mechanical properties of marble, as evidenced by degradations in strength, deformation, and energy parameters. The reversible deformation evolutions of the rock under two stress paths were diametrically opposed. DSI results revealed that the microcellular mechanical parameters of hornblende and dolomite exhibited greater variability, although both conform to Weibull distribution functions. Additionally, NMR analysis showed that the porosity of the marble was 1.6% initially and increased to 3.3%, 4.1%, 5.8%, and 10.9% after 2, 4, 6, and 8 thermal cycles, respectively. The coupled thermal-mechanical damage constitutive model can effectively describe the deformation behavior of marble under complex perturbations, with distribution parameters m₀ and T₀ decreasing linearly with the number of thermal cycles.

Traditional deterministic numerical simulation often has a poor prediction performance for landslide-induced wave run-up (LIWR) hazards, as it neglects the effects of uncertainty. The limitation for efficiently quantifying the uncertainties in primary parameters remains largely unsolved. In this study, we propose a probabilistic evaluation method, integrating the adaptive Kriging (AK) metamodel method and probability density evolution method (PDEM) based on generalized F-discrepancy. A Taylor expansion-based adaptive design strategy is applied to construct the global AK model over representative points generated by generalized F-discrepancy, thereby approximating the numerical physical response (i.e., maximum LIWR). Using these approximate responses, the PDEM is used to compute the exceedance probabilities that LIWR heights exceed elements at risk based on a construction of virtual time, and then a probabilistic criterion is introduced to classify hazard zones. The proposed method is demonstrated via two examples: Example Ⅰ, which possesses risk element (building), and Example Ⅱwith water-level variations. The results indicate that the proposed method has an acceptable performance (showing a 1.7 % difference in exceedance probability compared to Monte Carlo simulation with 50,000 samples) with low computation cost (requiring 284 deterministic analyses). For two specific scenarios in this study, the wave induced by the landslide exhibits a solitary-like leading wave. The proposed probabilistic method provides promising prospects for quantifying LIWR uncertainties, and is helpful for direct, efficient, and low-cost quantification assessment of cascading hazards.

The mixed rock-ice deposits in high-latitude areas usually come from the accumulation of rock-ice avalanches. Melting tests and temperature-controlled triaxial tests were conducted on rock-ice mixture samples with varying volumetric ice contents (0.25, 0.5, and 0.75), environment temperatures (0.5 ℃, 1 ℃, and 1.5 ℃), and temperature control durations (20 min, 40 min, and 60 min), aiming to investigate the thermodynamic behavior of rock-ice mixed deposits under an ablation environment. Our findings reveal that the melting behavior of rock-ice mixtures mainly occurs in the surface layer; then, ice meltwater transports along the surface seepage path to the bottom of the sample. Notably, the basal meltwater gathering zone leads to accelerated melting of the ice debris, and the cohesion and occlusion between the rock debris in this zone almost disappear, ultimately resulting in severe basal damage. Triaxial test results indicate that the basal damaged zone leads to an easy initial compression process of the rock-ice mixture samples and forms a basal strain effect. Statistics show that ice content, environment temperature, and temperature control duration all show a negative impact on the mixture's peak strength in thaw environments, which also exacerbates the basal strain effect, with a maximum basal strain of 8.61% and a corresponding mass loss ratio of 28.69%. Finally, the mechanisms of the secondary sliding of the mixed deposits and the failure mode of the rock-ice deposit dams induced by ice debris melting were discussed.

Water-rich sand layers are frequently encountered as adverse geological conditions during underground construction. Polymer slurry grouting has been widely recognized as an effective technique for reducing permeability and enhancing the stability of such strata. In this study, a mathematical model is established to describe the diffusion behavior of polymer slurry in porous media under dynamic water conditions and is further validated through laboratory experiments. The theoretical formulation of the slurry permeation process is developed based on Darcy's law, the Hagen-Poiseuille flow principle, and the physicochemical characteristics of the slurry. The derivation primarily focuses on analyzing the dynamic response of the slurry under the influence of water flow, considering the effects of flow velocity, grouting pressure, and sand-layer porosity on diffusion behavior. To verify the proposed model, a visualized grouting simulation system was designed to observe the diffusion process of polymer slurry in water-rich sand layers. The results demonstrate that slurry diffusion is significantly affected by grouting pressure, porosity, and water flow velocity. The observed staged diffusion characteristics, dynamic evolution patterns, and directional effects are in good agreement with theoretical predictions. Furthermore, the average relative deviations between the theoretical and experimental results for diffusion pressure and diffusion distance are both less than 25 %, confirming the reliability of the proposed model. Additionally, this study identifies distinct differences in slurry diffusion between porous and void media. In porous media, slurry propagation encounters greater hydraulic resistance, leading to rapid pressure attenuation and a limited diffusion range. Conversely, diffusion in void media occurs more smoothly due to the continuous cavity structure, resulting in slower pressure decay and a substantially larger diffusion radius. These findings elucidate the mechanisms governing slurry diffusion under dynamic water conditions and provide a theoretical basis for optimizing grouting parameters and improving construction efficiency in water-bearing strata.

Accurate extraction of rock mass discontinuity parameters is crucial for stability assessment and engineering safety. High-resolution remote sensing facilitates automated extraction, but its effectiveness relies heavily on precise normal estimation to ensure geometric reliability. Conventional methods struggle to preserve sharp features such as edges and corners, thereby reducing accuracy. To address this, we propose a normal estimation method based on local geometric adjustment that enhances feature extraction while maintaining sharp geometries. The approach consists of four steps: (1) classifying points, (2) applying normal and axial projections, (3) fitting segmentation lines via least squares, and (4) refining normals by optimizing local neighborhoods. The proposed method was evaluated on computer-aided design (CAD) models, real objects, and rock mass point clouds, and benchmarked against eight representative algorithms, including principal component analysis (PCA), 2-Jet PCA, Voronoi-based PCA, PCPNet, neural gradient function (NeuralGF), low rank representation (LRR), normal estimation via shifted neighborhood (NSN) and pair consistency voting (PCV). Experimental results demonstrate that our method achieves superior accuracy and efficiency, significantly improving structural plane extraction and ensuring better preservation of sharp geometric features.

Rock mass discontinuities arise from tectonic movements and other geological processes, reflecting the evolution of the Earth's crust. These discontinuities significantly influence the physical properties, deformation characteristics, and energy release mechanisms of the crust. Therefore, recognizing discontinuities is crucial for understanding the evolution of geological structures, analyzing the physical and mechanical properties of geological bodies, and investigating geological hazards. Traditionally, discontinuity recognition has relied on manual interpretation or automated algorithms based on pixel brightness. However, these methods often struggle to strike a balance between efficiency and robustness. To overcome these limitations, we leveraged deep learning techniques that integrate the strengths of both approaches, enabling the recognition of automated discontinuity with expert-level accuracy. To accomplish this objective, we developed and open-sourced the first large-scale deep learning database for rock mass discontinuities, featuring over 300,000 annotated discontinuities. The YOLOv8x-seg model was extensively trained on this database and evaluated across diverse and complex scenarios. The results demonstrated the model's capability to accurately recognize discontinuities even under challenging conditions. Furthermore, we expanded the test set to include rock masses from various global locations, as well as underground rock masses, soils, and artificial structures, where the model consistently achieved effective recognition. The model consistently delivered accurate results, highlighting its strong generalization capability. A comparative analysis revealed that its performance closely aligns with expert manual interpretations. Our open-source database enables researchers to train various deep learning models and achieve equally high-performance results.

In hard rock tunnel excavation, controlling the blasting profile to prevent overbreak and underbreak is critical for safety and cost-effectiveness. Discontinuities such as joints and faults significantly affect the mechanical properties of the rock mass, and their distribution critically influences the blasting outcomes. This study explores the impact of joint distribution on the tunnel blasting profile through field measurements and numerical simulations. Real-time monitoring of the tunnel face was conducted using the digital twin method, capturing both rock discontinuities and blasting profiles. Field results revealed that overbreak tends to occur at joints outside contour boreholes, where the joints lead the blasting profile diverging from the borehole connection line. To quantify this effect, dynamic finite element simulations were conducted to assess the influence of borehole-joint distances (d = 25 cm, 50 cm, and 100 cm) and intersecting joint angles (α = 60°, 90°, and 120°) on blasting stress wave propagation and rock fracture development. The results demonstrated that joints within the hard rock mass guide and restrain the propagation of blasting stress wave, leading to the formation of a fracture zone induced by the reflected stress wave (the RSW fracture zone). The morphology of the RSW fracture zone closely matched the field blasting profile, validating the numerical simulation results. Furthermore, the borehole-joint distance and the intersecting joint angle were found to govern the extent and geometry of the RSW fracture zone. These findings provide valuable insights for optimizing blasting designs in jointed hard rock masses to control tunnel excavation profiles better.

Timely identification of accelerating precursors and performing reliable time-to-failure analysis are the key components in the management of slope failure risks. This study focuses on rock slope failures and proposes a framework for online identification of accelerating precursors and dynamic probabilistic prediction of failure time grounded in Bayesian inference. By integrating the Bayesian online change-point detection (BOCD) method with a typical dimensionless trend (TDT) model, the BOCD-TDT algorithm is first developed for online identification of acceleration events and their corresponding onset of acceleration (OA). Subsequently, a Bayesian approach is employed to estimate the parameters of the inverse velocity (INV) method, enabling the dynamic probabilistic prediction of slope failure time while quantifying observational and model uncertainties across different accelerating deformation stages. Building on this, the influence of starting point (SP) selection, trend update (TU), and multi-data fusion on prediction reliability is evaluated, and a novel decision criterion for impending slope failure is proposed. The feasibility of the proposed methods is then validated using 73 rock slope failure cases. Results show that using INV data, the BOCD-TDT algorithm can reliably identify acceleration events and the corresponding OA. In time-to-failure analysis, the reliability of dynamic failure predictions can be enhanced by incorporating both observational and model uncertainties corresponding to the deformation stages into the Bayesian prediction model, along with TU detection and multi-data fusion. The proposed failure probability criterion provides valuable guidance for the identification of impending failure and the establishment of ultimate alert thresholds.

In this study, the influences of the thermoelastic effect and fluid viscosity-temperature effect (VTE) on hydraulic fracture growth in deep reservoirs were investigated. A computational model that integrates the thermoporoelastic effect and VTE was developed on the basis of the displacement discontinuity method (DDM). The temperature distribution within fractures is determined using a first-order upwind scheme. Using this simulator, this study systematically evaluated the impacts of the poroelastic stress, thermoelastic stress, and VTE of the fracturing fluid on fracture propagation. Furthermore, the dominant controlling factors were identified in both the viscosity- and toughness-dominated regimes. The results show that (1) the thermoelastic stress exhibits behavior opposite to that of poroelastic stress, reducing the injection pressure and increasing the fracture width. (2) Under viscosity-dominated conditions, the influence of the VTE is more remarkable, whereas the thermoelastic effect on fracture propagation is relatively weak. Under toughness-dominated conditions, the influence of the thermoelastic effect on fracture propagation remains relatively weak, and the VTE can essentially be disregarded. (3) When proppant transport is considered, for small proppant particles, the transport distance increases from 88 m to 100 m when the VTE is considered because the VTE increases the fracture length. For large proppant particles, owing to the decrease in viscosity with increasing temperature, the proppant transport distance is significantly reduced from 86 m to 70 m. These results indicate that reasonably selecting the proppant size and paying more attention to the VTE of the fracturing fluid in deep reservoir fracturing are crucial.

This study investigates the effectiveness of combined tip-and-side post-grouting on large-diameter bored piles in deep fine sand layers. Field tests were conducted on nine piles for the Shishou Yangtze River Highway Bridge project. A detailed comparison of pile performance pre- and post-grouting assessed the technique's influence on ultimate bearing capacity and side resistance. The distribution and effectiveness of the cement grout were analysed using core drilling and the standard penetration test (SPT). An equation correlating post-grouting side resistance with the pre-grouting SPT index (N_SPT) was established. Results demonstrate a substantial improvement in pile bearing capacity after grouting. Ultimate bearing capacity increased by 76 %-152 % after grouting. Longer piles on the main bridge exhibited more pronounced enhancement, achieving ultimate capacities 145 %-206 % higher than those of the shorter approach bridge piles. This is attributed to the greater total cement volume applied along their sides. Critically, combined grouting outperformed side-only grouting, enhancing both side and tip resistance. Core drilling confirmed the spread of cement grout around the piles, confirming the method's effectiveness. SPT results indicated significant increases in the soil N_SPT adjacent to the piles following grouting. These findings provide directly applicable data for designing the bridge pile foundations and offer essential guidance for comparable projects in deep fine sand layers.

Tunnel portal sections have historically been more susceptible to earthquakes than other components, exhibiting significant seismic damage. However, critical seismic behaviors of portal sections remain unrevealed owing to insufficient consideration of actual topography. Moreover, the extent of asymmetric seismic responses induced by topography remains unclear, which is essential for seismic design. To overcome these limitations, this study replicated the actual geological conditions of a tunnel portal section, including the portal slope, topography, slope and tunnel supports, and the often-overlooked portal wall using large-scale shaking table tests. The asymmetric seismic responses and their impact ranges identified in the experiments were validated through numerical simulations. The results revealed that the seismic damage to the slope is attributable to the presence of the tunnel, with slope acceleration near the tunnel portal increasing by 20 %-40 % compared to slopes without a tunnel. Additionally, the tunnel facilitates seismic wave propagation in specific directions, leading to further seismic damage across the portal section. Portal walls, being exposed structures, are susceptible to higher seismic strain and acceleration than tunnel linings and thus warrant increased attention. Importantly, the asymmetric seismic response was found to vary based on different sides and influence ranges. Within 15 m of the portal, the tunnel was dominated by the open-side asymmetric response of acceleration, strain, and displacement. From 15 to 35 m range, the seismic response of the mountainside was more pronounced, exhibiting increased seismic earth pressure and stress on the right sidewall. Seismic earth pressure and stress diminished within the 35-75 m range and steadily decreased beyond 75 m. This enhanced understanding of seismic behaviors facilitates the targeted establishment of future seismic fortifications based on these classified ranges.

Taking the Banbiyan dangerous rock mass as the focus, this study employs field investigations, model experiments, and numerical simulations to explore the instability mechanisms of dangerous rock masses on bank slopes containing a single shear band under the deterioration of reservoir water. The results indicate that the failure mode of the dangerous rock mass is collapse of rock mass in the hydrofluctuation belt (HFB) - internal damage to the dangerous rock mass - development and through-going of fractures on both sides - sliding failure of the lower rock detaching from the parent rock. As the shear band gradually deteriorates, stress concentration develops around it near the highest water level. Within the rock mass close to the highest water level, a phenomenon of unloading occurs, and the pore water pressure at the shear band-bedrock interface eventually exceeds that within the rock mass of the HFB. In the numerical simulation, before 40 dry-wet cycles, the damage zone is concentrated near the shear band above the highest water level. Afterward, it concentrates around the fractures on both sides of the dangerous rock mass. The sensitivity of different shear band characteristics to the stability of the dangerous rock mass is ranked as follows: the height-length ratio of the shear band-bedrock interface, followed by the filling material thickness, dip angle, width, and degree of fragmentation. The findings can provide valuable reference for the stability and prevention of such dangerous rock masses.

In the natural environment, the soil structure can be weakened by temperature fluctuations and climatic changes. Nevertheless, the dynamic behavior of expansive soils, especially those with high swelling and pronounced fissure properties, subjected to wetting-drying-freeze-thaw (WDFT) cycles has been rarely investigated. Undisturbed and remolded samples, made of Xinjiang's highly expansive soils, were evaluated in this study through comprehensive resonant column tests conducted at several confining pressures and WDFT cycles. A typical hyperbolic model demonstrated the decay law of shear modulus with strain. An estimated model of the maximum shear modulus, incorporating the two factors, was developed, and it was found to be in good agreement with the measurement results. The results reveal that strain, WDFT cycle, and confining pressure have qualitatively uniform effects on the shear modulus of natural soils containing fissures and recompacted samples. However, the maximum shear modulus of the undisturbed samples is lower by 0.83-13.24 MPa due to the presence of initial fissures, except for the confining pressure of 400 kPa. Also, their responses to confining pressure are more significant, with the shear modulus increased by up to 20 %-124 % relative to that at 25 kPa. Furthermore, the relative difference in the shear modulus (up to about 60 %) between the two samples tested under low confining pressure conditions deserves special attentions. The quantitative differences in shear modulus and cumulative damage effect of the tested samples are attributed to the initial fabric and microstructural evolution, as observed by Scanning Electron Microscope (SEM). This research enriches the theoretical framework for analyzing the ability of soils to resist shear deformation under small strain, which is instructive for disaster prevention and mitigation in expansive soil regions, considering the effects of climate change.

Callovo-Oxfordian (COx) claystone has been selected as the host rock formation for the deep geological disposal of radioactive waste in France, called the Cigéo project. The excavation of drifts in the COx formation induced damage zones with an anisotropic shape, while the stress state around the drifts is almost isotropic. This is due to the anisotropic properties of the host rock formation and the instability caused by the brittle damage. In this study, the mechanical anisotropy of COx claystone was investigated through a triaxial shear test, where the axial stress was maintained while the lateral stress was decreased. Such a method was proposed for simulating one of the possible unloading paths involved during the excavation. The triaxial samples were prepared along different directions based on the angle between the axial loading direction and the one perpendicular to the bedding plane. Results show that the stress-strain curve exhibited an elasto-plastic pattern. With increasing deviatoric stress, a minor decline in Young's modulus E was observed, suggesting progressive damage behaviour. The shear strength changed with increasing the loading angle, showing the anisotropic property of COx claystone. Moreover, the results in this study and collected from other works show a time-dependent behaviour of COx claystone. It is attributed to the coupled effect of creep and pore pressure dissipation inside claystone.

Landfill cover system plays a crucial role in reducing leachate generation by limiting rainwater infiltration. This paper evaluates the field performance of a polymer-enhanced three-layer cover system at a leather sludge dump site in Xinji city, China over a 1-year monitoring period. Waste soil (WS), sand-bentonite mixture (SB), and sand-polymer-bentonite mixture (SPB) were used as the low-permeability layer, respectively, in three test areas, above which the fine-grained cultivated soil and gravel were used in the top and middle layers to form a capillary barrier. During the 1-year monitoring period, the recorded cumulative rainfall was 452.1 mm, and the volumetric water content (VWC) at the top layer fluctuated significantly from 0.13 to 0.45 in response to rainfall and evaporation, but that of the low-permeability layer maintained stable for both cover SB and SPB. No water percolation was detected during the 1-year monitoring period. Furthermore, numerical simulations were carried out to assess the anti-seepage performance under more extreme climatic conditions (i.e., higher rainfall intensity and long-term deterioration of soil permeability). Numerical simulations corroborated the field observations that the SPB layer effectively minimized percolation even under extreme climatic conditions. For example, under the most unfavourable conditions, the computed annual percolation through the cover SPB was 4.7 mm, as low as 27.2% and 8.1% that through the cover SB (=17.3 mm) and WS (=57.9 mm). Overall, the results suggest that the polymer-enhanced three-layer soil cover is a promising alternative to traditional geomembrane-based covers and/or thick composite soil covers.

The actively-heated fiber-optic (AHFO) method can near-continuously measure soil water content along the AHFO sensors by sensing the temperature variation during an actively heated pulse. Different heating materials, structures, and fiber-optic temperature sensing techniques significantly impact the measurement performance of AHFO sensors. However, there has been no systematic evaluation regarding the measurement performance of soil water content by different AHFO sensors. To address this issue, this study focuses on the measurement performance and monitoring potential of six different AHFO sensors (i.e. actively-heated fiber Bragg grating (AH-FBG) alundum tube, AH-FBG cable, carbon fiber heated cable (CFHC), copper metal heated cable (CMHC), CFHC sensing tube, and CMHC sensing tube). Numerical models were built first for simulating the thermal response process of six AHFO sensors to quantify the measurement accuracy and sensitivity of soil water content. Then, the in situ applications of six AHFO sensors were carried out in Yan'an, China. The numerical and in situ monitoring results indicate that the measurement accuracy and sensitivity of soil water content are both highest by using CFHC sensing tube and CMHC sensing tube. CMHC sensing tube is most suitable for fine and accurate monitoring of in situ soil, while AH-FBG alundum tube and AH-FBG cable are best suited for long-term real-time remote monitoring. In practical applications, it is recommended that geotechnical engineers, when selecting AHFO sensors for a specific site project, should take into account a variety of factors, including measurement performance, spatial resolution, monitoring duration, site installation, and power supply conditions.

The stress-strain behavior of brittle siliceous mudstone coarse-grained soils (SMCGSs) under penetrating erosion critically affects the stability of SMCGS-filled embankments in erosion-prone areas, yet remains insufficiently understood, particularly regarding particle crushing and critical state behavior under low confining pressures. This study proposes a modified constitutive model to characterize erosion-induced mechanical degradation and nonlinear critical state evolution. A normalized parameterϑ, derived from the principle of crushing equivalence, is introduced to capture the coupled effects of particle breakage and critical state shifts under varying erosion intensities. Along with a nonlinear tuning index δ, this parameter is integrated into the unified hardening model for low confining pressure (UH-L), resulting in the N-UH-LE model. Consolidated drained (CD) triaxial tests under confining pressures of 100-400 kPa are conducted for model calibration and validation. The model predictions exhibit strong agreement with experimental results, with a maximum relative error of 7.76 %. The N-UH-LE model successfully reproduces key mechanical responses, including hardening, softening, shear dilation, and volumetric changes across different erosion levels. Furthermore, erosion-induced degradation decreases with lower confining pressures and higher initial void ratios (e₀ = 0.3, 0.5, and 0.7), while variations in interlocking strength (τ₀cotφ = 40 kPa, 80 kPa, and 120 kPa) show limited influence.© 2026 Institute of Rock and Soil Mechanics, Chinese Academy of Sciences. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).

The soil-water retention and soil shrinkage characteristics are both crucial constitutive relations for unsaturated soils. Although existing research has explored the correlation between these two characteristics to some extent, the underlying mechanisms remain inadequately investigated. To investigate the correlation between the soil-water retention and soil shrinkage behavior, a series of soil-water retention and soil shrinkage tests is performed on compacted clays over a wide suction range (0-367 MPa). The test results show that the pore water in compacted clays is first expelled from large pores in low suction range. The drainage of pore water at low suctions is predominantly responsible for the phase of structural shrinkage in the soil shrinkage curve. The consistency between the characteristic transitional water contents in the soil shrinkage curve (SSC) and the inflection points in the soil-water retention curve (SWRC) is identified for all the compacted clays. The bimodal pore-size distributions (PSDs) of different clayey soils are obtained using the mercury intrusion porosimetry. The bimodal pore-size distribution characterization is the intrinsic factor in shaping the bimodal morphology in the SWRC over a wide suction range. The low proportion of micropores in clays is responsible to the indistinct zero-shrinkage stage of the SSC. The microstructure measured by the scanning electron microscope indicates the manifestation of aggregation effects during desaturation process. The results demonstrate that soil shrinkage is primarily caused by the contraction of inter-aggregate pores, rather than the evolution of intra-aggregate pores. The findings can greatly enhance the understanding of the soil-water retention and mechanical behavior of compacted clays in varying water content conditions.

Traditional active earth pressure evaluations considering seepage are typically deterministic, assuming uniform soil layers. However, soil hydraulic properties exhibit the obvious spatial variability due to geomorphological processes or poor construction control. To address this, the random limit analysis method (RLAM) is employed to investigate the influence of spatial variability of saturated hydraulic conductivity on active earth pressure. To combine random field simulations with the limit analysis-based evaluation method, this study discretizes the conventional three-dimensional (3D) rotational failure mechanism. Owing to the energy dissipation principle, the explicit expression of 3D active earth pressures can be derived. The proposed method's validity is demonstrated through comparisons with available analytical solutions, deterministic numerical calculations, and random finite difference method (RFDM). RLAM integrating with Monte Carlo simulations (MCS) in MATLAB, facilitates the probabilistic analysis of the active earth pressure to be evaluated. The findings indicate that the present method not only incorporates the spatial variability of hydraulic properties, but also enhances the computational efficiency of calculating active earth pressures compared to the RFDM. Based on extensive uncertainty analyses, this study proposes a system reliability evaluation method for semi-gravity retaining walls, accounting for the spatial variability of saturated hydraulic conductivity. The results reveal that under different random field design scenarios, all decay curves of system failure probabilities for a semi-gravity retaining wall intersect within a specific range, referred to herein as the "turning region". Furthermore, as the normalized horizontal autocorrelation distance, anisotropic ratio and coefficient of variation increase, the effective influence zone of the wall design index on system failure probability gradually expands, offering valuable guidance for the design and construction of semi-gravity retaining walls.

This research introduces a powerful tool, the automatic parametrization of hardening soil (HS) model (APHS), designed to make the HS model parameterization process easier and faster than conventional methods while maintaining high accuracy. Traditional parameterizations rely on oedometer tests, unloading-reloading data, or domain-specific assumptions. Existing optimization-based models often assume uniform parameter weighting, potentially overlooking the distinct sensitivity of each parameter. APHS addresses these limitations as a standalone tool that relies exclusively on conventional triaxial loading test data. To achieve this goal and address the scarcity of labeled datasets, this study integrates numerical modeling with deep learning. The study focuses on a typical shallow Hong Kong soil with parameter ranges derived from field data and relevant literature. Latin hypercube sampling generated diverse parameter values within theoretical bounds for reliable input, while a two-dimensional (2D) axisymmetric finite element model (SIGMA/W) simulated laboratory tests to create a comprehensive, labeled dataset. Seven novel multi-parallel deep long short-term memory (LSTM) networks were trained and validated, achieving an accuracy of 99.4 %. Validation against a conventionally parameterized reference case confirmed 99.6 % accuracy, while an experimental laboratory case study demonstrated strong agreement between simulated and measured results. APHS accelerates HS model parameterization, delivering accurate results in seconds. It can seamlessly integrate with finite element models for automated laboratory data processing and physically informed models to refine calibration parameter ranges. Future work will expand its applicability to various conditions and parameters.

Compacted bentonite blocks are proposed for buffer barriers in deep geological repositories for high-level radioactive waste (HLRW) disposal. These blocks, manufactured through uniaxial compression in molds, exhibit heterogeneity that may impact long-term buffer performance. This study focuses on the physical and hydro-mechanical heterogeneity of full-scale blocks induced by the compaction process. Sector-shaped blocks, with radii of 600 mm and 1200 mm and a height of 200 mm, were axially compressed. Key parameters, including water content, dry density, elasticity modulus, swelling pressure, and permeability, were measured to assess the heterogeneity. Results show that the heterogeneity in the upper layer is primarily caused by differences in drainage and gas expulsion pathways. As depth increases, water content and dry density become more correlated. Hydro-mechanical behavior is largely controlled by dry density, but its fluctuation ratio is much higher than that of dry density. Regarding the microstructure, pore structure heterogeneity follows the order: corner regions > edge regions > center regions, and upper layer > middle layer > lower layer. Vertical microcracks also develop to varying degrees, increasing the anisotropy of the blocks. Upon these observations, the study thoroughly discusses the feasibility and challenges of reckoning the hydro-mechanical properties of blocks using dry density distribution alongside laboratory-scale data. Additionally, it proposes an indicator to evaluate the overall heterogeneity of buffer blocks. These findings highlight the inherent heterogeneity of compacted bentonite blocks at the engineering scale, providing valuable insights for future experiments and simulations.

Excavation-induced retaining wall deflection (RWD) significantly influences the safety of surrounding built environment. To predict the three-dimensional RWD in heterogeneous strata, a new partial differential equation (PDE) is derived in this study, and two prediction models are proposed, i.e. the physics-informed neural network (PINN) model and the data-driven PINN model. As a physical constraint, the new PDE is crucial to the loss functions of these models. Then, the validity of the models is verified and analysed using a subway deep-foundation pit. The results show that the training times of both models are controlled within 900 s, which is a significant reduction compared to that of the conventional numerical model. In addition, the prediction accuracy of the data-driven PINN model is higher than that of the numerical model, while that of the PINN model is slightly lower than that of the numerical simulation. However, in contrast to the data-driven PINN model, the PINN model can identify irregular soil interfaces in heterogeneous strata to learn the deflection continuity conditions at irregular interfaces and realize RWD prediction in non-uniform distributed strata. In practical applications in foundation pit engineering, the selection of the PINN and data-driven PINN models can be conducted according to the in situ distribution conditions of the strata to enable the early prediction of potential RWD, thereby providing a reliable basis for the further optimisation of retaining structures design.

Effective sealing of geological fractures is essential for subsurface stability and mitigating environmental risks such as groundwater contamination and inefficient CO₂ sequestration. Enzymatically Induced Carbonate Precipitation (EICP) offers a promising bio-mediated approach due to its ability to fill and seal fractures. However, real-time precipitation patterns and clogging behavior of EICP under varying fracture and flow conditions remain poorly understood. This study employs a transparent fracture model with visualization to systematically investigate the effects of fracture aperture, flow conditions, and surface roughness on EICP-mediated sealing. Results indicate that fractures with narrower apertures promote tortuous finger-like flow paths, while wider-aperture fractures show more uniform deposition, with fewer but wider preferential flow paths. An appropriate injection rate around 1 mL/min ensures uniform precipitation and effective clogging, avoiding inlet clogging at lower rates (0.1 mL/min) and flushing effect reducing deposition at higher rates (10 mL/min). Additionally, rough fractures exhibit higher precipitation efficiency and greater permeability reduction, driven by their irregular surface geometry, which creates more deposition sites and complex flow compared to smooth fractures. Image processing reveals that precipitation patterns in rough fractures match closely with aperture distribution, compared to more concentrated deposition in smooth fractures. These findings provide insights for optimizing EICP-mediated fracture sealing, with implications for groundwater protection and geotechnical practices.

Supersulfated cement (SSC) is considered an environmentally friendly alternative to ordinary Portland cement (OPC), while its stabilization efficiency on dredged sediment (DS) is still unclear. Three types of SSC were prepared by combining ground granulated blast-furnace slag, alkali-activator NaOH, and a sulfate waste source, yielding SSCE (from electrolytic manganese residue), SSCP (from phosphogypsum), and SSCD (from desulfurization gypsum). To further enhance the stabilization efficiency of SSC on DS, nano-SiO₂ (NS) and nano-Al₂O₃ (NA) were incorporated individually and as a composite blend. Mechanical properties and microstructural analyses were conducted to evaluate the stabilization efficiency and elucidate the underlying mechanisms. The leaching toxicity of SSCE-stabilized DS was investigated via leaching tests. The results showed that both alkali-activation and nano-modification can significantly improve the strength development of SSC-stabilized DS. At least 15 % NaOH was required for SSC to achieve the same stabilization efficiency as OPC. The optimum NA-modified SSCD-stabilized DS demonstrated superior strength compared to OPC-stabilized DS. Composite NS/NA-modification was more efficient than using NS or NA individually. For DS stabilized with SSCE, SSCP, and SSCD, the optimal NS-to-NA mass ratios were 7:3, 3:7, and 3:7, respectively. Notably, the nano-modified SSCE-stabilized DS showed no environmental risks. Incorporating NS and NA into SSC-stabilized DS respectively promoted the formation of C-S-H gel and ettringite. A micro-mechanism model was developed to explain the strength evolution of nano-modified SSC-stabilized DS. This study provides a theoretical basis for the application of SSC in DS stabilization, and facilitates the collaborative resource utilization of industrial solid wastes and DS.

This study investigates particle crushing mechanisms in granular soils during shearing through staged triaxial compression experiments performed at prescribed axial strains and varying confining stresses, integrating a high-performance acoustic emission (AE) measurement system. The study analyzed particle crushing-related parameters using grain size distribution (GSD)-based indices (relative breakage index B_r and its rate ΔB_r) and AE-based parameters (high-frequency AE hits and hit rates ). The results confirm the feasibility of high-frequency AEs (>100 kHz) in comprehensive quantification of particle crushing, with a strong linear relationship observed between and B_r. Significant particle crushing occurs within the initial 5 % of axial strain, which correlates with the yielding and peak-stress phases. This process yields fragments with a size range of 0.425-2 mm. Increased confining stresses result in a steady rise in B_r and , suggesting that large strains are required for stable particle grading. The evolution trends of different high-frequency AE ranges reveal a shift to complex crushing mechanisms, such as particle abrasion/grinding and corner breakage/particle splitting, highlighting the role of stress and strain levels in influencing particle damage behavior.

Incineration bottom ash (IBA) holds attractive potential as a construction material, yet its shear behavior under cyclic loading remains insufficiently understood. This study comprehensively characterizes the monotonic and cyclic simple shear behavior of Singapore-derived IBA under constant volume conditions, with particular emphasis on its reuse potential in dynamic load-bearing applications. Key findings reveal that: (1) The material exhibits marked strain-hardening characteristics, demonstrating a density-dependent friction angle increment from 38.3° (loose state) to 42.5° (dense state). (2) Mechanical performance shows strong dependence on Si-Ca-Fe/Al ternary chemical composition and particle gradation characteristics. (3) Distinct failure modes emerge under different loading conditions - liquefaction dominates under unidirectional cyclic simple shear (UDCSS) conditions at low cyclic stress ratios (CSRs) and confining pressures, while bidirectional cyclic simple shear (BDCSS) loading induces cyclic mobility failure at elevated CSR levels, with corresponding cyclic resistance ratios (CRRs) showing a 30 % reduction in BDCSS compared to UDCSS configurations. (4) Pore pressure ratio (R_u) evolution follows a triphasic pattern: liquefaction failures exhibit rapid R_u acceleration in initial and tertiary phases (terminal R_u > 0.9), contrasting with cyclic mobility failures characterized by decaying R_u growth rates and lower terminal R_u values. (5) Notably, the established correlation between CRR and normalized shear wave velocity (V_s1) aligns closely with that of sand-gravel mixture with 5 % fines, which demonstrates the comparable cyclic load-bearing capacity of IBA to that of conventional construction materials. The study highlights the effect of load direction, particle size, and mineralogy in design applications and supports IBA's suitability for reuse in infrastructure subjected to dynamic loads.

To realize the soil reinforced through the carbonation of ternary binder under ambient pressure and mild conditions, the present study introduces triethanolamine (TEA), which serves as an effective carbonation accelerator. Through the unconfined compressive strength (UCS) test, the soft soil solidified with ternary eco-binder consisting of ground granulated blast-furnace slag (GGBS), metakaolin (MK), and calcium carbide residue (CCR), subjected to carbonation, is investigated. The effect of TEA on the carbonation of soil is evaluated by the UCS and the CO₂ mineralization. This study clarifies the influence factors, including the initial water content, TEA dosage, binder constituent ratio, and content. The optimal binder constituent ratio for the strength growth and carbonation efficiency of carbonated soil is approximately 4:4:2 for GGBS, CCR, and MK, respectively. The incorporation of TEA at a low dosage (<0.15 %) enhances the strength of carbonated soil, whereas the high dosages impair the strength. The synergistic effect of TEA and carbonation further improves the strength and compressibility of soil. The soil with 1.5 % TEA carbonated for 7d exhibits a 44.8 % increase in strength compared to that without TEA, which is attributed to a 2.2-fold increase in carbonation efficiency. The addition of TEA accelerates the ion dissolution and CO₂ dispersion, promoting the carbonation reaction in soft soil. Calcite and aragonite precipitate during carbonation, contributing to the strength development of soil. The carbonates phase difference and the pore structure density with different TEA dosages are also demonstrated to be the strength influence factors.

Stratigraphic interface characterization and strength parameter assessment of geomaterials constitute fundamental research priorities in geological and geotechnical engineering. While measurement while drilling (MWD) and drilling process monitoring (DPM) have emerged as critical techniques for acquiring real-time drilling parameters, inherent limitations in data interpretation persist. The critical challenge of random fluctuations in MWD-derived penetration rate measurements exhibits poor correlation with the stratified homogeneity characteristics of geological formations. Such discrepancies undermine the reliability of stratigraphic classification and mechanical property analysis. Through systematic comparison of MWD and DPM datasets combined with quantitative parameter evaluation, this investigation reveals significant methodological distinctions in data acquisition accuracy. Machine learning-enhanced analysis employing Support Vector Machine (SVM) algorithms demonstrates that DPM-derived parameters provide superior stratigraphic identification capabilities. Our findings indicate that DPM implementations achieve 20.57 % and 38.01 % higher resolution in interface detection along two drill-holes compared to the conventional MWD approaches. This improvement allows for better prediction of stratigraphic profiles and more precise guidance in subsequent geological and geotechnical engineering practices.

Landfill facilities around the world are designed to protect the environment and public health by using impermeable liner systems that isolate the waste and leachate produced from the waste. However, the functionality of liners has been reported to be significantly compromised by environmental loading due to the seasonal climatic and physico-chemical changes that alter their volume deformation and hydraulic characteristics. Bentonite admixed natural soils are employed as liner materials if they meet the hydraulic conductivity requirement in their as-compacted state. However, limited studies addressed the effects of wet-dry cycles combined with chemical contamination on the volumetric and hydraulic behaviour of bentonite admixed natural soils. In this study, Indian red soil was ameliorated with 10%, 20%, and 30% bentonite by weight, and the mixtures were subjected to alternate wetting and drying cycles using distilled water, 0.4 M NaCl, and 0.4 M CaCl₂ solutions. All red soil-bentonite specimens met the hydraulic conductivity design criterion of 1 × 10^-7 cm/s in their as-compacted states. However, significant variation in hydraulic behaviour was observed at the end of the wet-dry cycles, particularly with chemical contamination. The microstructural examination through scanning electron microscopy (SEM) and mercury intrusion porosimetry (MIP) revealed an increase in macropores volume with wet-dry cycles and increase in the induced osmotic suction, which was found to be a key factor influencing the hydraulic conductivity.