The radial basis function collocation method suffers from domain truncation errors for unbounded problems, severely ill-conditioned matrices, and high sensitivity to the shape parameter. This study proposes a transformed radial basis function collocation method (TRBFCM), which applies integral transforms to reduce the dimensionality. The new framework can inherently avoid artificial domain truncation and yield smaller algebraic systems with enhanced numerical stability. Numerical results demonstrate that, compared with the standard RBF method, the TRBFCM achieves higher accuracy and maintains this accuracy over a much wider range of shape parameters. Moreover, it outperforms both the finite difference and the finite element methods in terms of accuracy and efficiency. The solution accuracy is found to depend on the choice of radial basis functions, the numerical inverse transform techniques, and the type and number of collocation points. Analyses involving infinite temporal and spatial domains confirm that the method overcomes finite-domain limitations and reduces boundary-related errors. Overall, the proposed method provides an efficient and robust framework for solving multi-dimensional problems in complex domains.

Layered unsaturated soils are a prevalent form of shallow soils, and their consolidation process is pretty complex due to the interaction of three phases, including solid, water, and air. In practical ground improvement projects, sand drain techniques are commonly employed to accelerate the consolidation rate in the horizontal direction. Therefore, the consolidation process cannot be simplified as a one-dimensional problem. This study established a two-dimensional consolidation analysis system for layered unsaturated soil media, considering the flow of both pore water and pore air, as well as the continuity conditions between unsaturated soil layers. Subsequently, the static equilibrium equations and the constitutive equations for unsaturated soils are incorporated into the system to obtain the deformation distribution at any point within the unsaturated soil media over time. A novel solution to this system is derived based on the transformed differential quadrature method by combining the Laplace integral transform technique and differential quadrature rules, where the former is employed to address the time-dependent partial differential terms, and the latter is utilized to discretize the spatial domain. The inverse Laplace transform is then conducted to obtain the solution in the physical domain. The proposed solution is validated by comparing the results with existing analytical solutions. Furthermore, the effects of permeability coefficients, mechanical properties of the unsaturated soil interlayer, and the horizontal spacing of sand drains on the two-dimensional consolidation behavior of layered unsaturated soil media are analyzed.

Coral sand is widely used in marine construction; however, its mechanical response under thermal-hydraulic coupling conditions, particularly during the artificial ground freezing process, remains insufficiently studied. This study investigates the thermal-hydraulic coupling effects on the temperature field evolution, particle breakage, and shear strength of frozen coral sand through macro- and micro-scale experiments, including unidirectional freezing, direct shear, particle size analysis, and scanning electron microscopy observations. Results show that the seepage effect has a greater influence on the temperature field of frozen coral sand and is mainly concentrated in the initial freezing stage. The greater the seepage velocity, the slower the freezing efficiency. Thermal-hydraulic coupling increases the proportion of medium-sized particles (0.125-0.5 mm) due to frost-induced breakage of large particles, accompanied by pronounced changes in particle morphology from sharpness to rounded. Under the coupled conditions, the shear strength in the phase-change region increased more significantly at other seepage velocities compared to the no-seepage case. This is attributed to intense particle crushing and enhanced interlocking induced by the coupling of freezing and seepage, whereas the strength was lowest under no seepage. Overall, both the temperature field evolution and shear strength development of coral sand are governed by particle breakage. The heat absorbed by particle breakage and the pore structure reorganization lead to changes in permeability, resulting in a slower rate of temperature decrease, while the small particles produced by active particle breakage within the phase transition and frozen zone form a denser skeleton structure through the pore filling effect, which significantly enhances the shear strength. These findings clarify the dominant role of particle breakage in controlling the thermal and mechanical behavior of frozen coral sand under thermal-hydraulic coupling and provide valuable guidance for artificial freezing applications in the South China Sea.

Prefabricated energy shafts represent a technological paradigm shift for coastal urban geothermal systems by integrating structural support with active heat exchange within prefabricated components, thereby overcoming critical constraints related to space and complex hydrogeology. This study investigates the thermo-hydromechanical performance of such energy shafts in coastal soft soil areas using a multiphysics numerical model. It evaluates the synergistic effects of employing CuO nanofluids as a heat transfer medium and the influence of groundwater seepage. The results suggest that CuO nanofluids show improved heat exchange capacity per unit depth by approximately 26 % to 29 % under both cooling and heating modes compared to water, primarily due to improved thermal conductivity and intensified micro-convection around nanoparticles. Furthermore, numerical predictions indicate that nanofluids may effectively mitigate thermal stress by optimizing temperature field distribution, reducing maximum tensile and compressive stresses in the lining by 14.5 % to 19.5 % under the model assumptions. Groundwater seepage markedly improves steady-state heat exchange capacity by up to 32 % through enhanced convective heat transfer and accelerates the stabilization of the stress field by promoting temperature field homogenization. These field-validated findings provide a preliminary theoretical reference only for performance optimization and preliminary structural design of 1.5 m single-ring basic heat-exchange units in prefabricated energy shafts, under short-term seasonal operation in saturated soft silty-clay strata of coastal areas. The results cannot be directly extrapolated to multi-ring continuous layouts, long-term cyclic operation, or other geological conditions.

Bedding rock slopes are prone to large-scale landslides subject to earthquakes, and their stability evaluation and prevention are key research focuses in the field of geological hazards. Taking a soft-hard interbedded bedding rock slope as the prototype, this study proposes a novel anchor with energy-dissipating and self-centering (ED&SC) functions. Large-scale shaking table tests are conducted to study dynamic responses of the bedding rock slope reinforced by two types of pile-anchor composite structures (PACS). It is found that the dynamic responses of the bedding rock slope exhibit obvious spatial differences affected by lithologic distribution, seismic intensity, waveform characteristics and excitation mode. The acceleration amplification factor (AAF) increases stepwise along multiple slope directions and evolves following a “decrease-increase- decrease” pattern within 0.050 g - 0.600 g. The AAF under the excitation of Wenchuan wave and bidirectional wave is obviously larger than those under Ludian wave and unidirectional wave. The slope exhibits progressive failure characteristics, sequentially undergoing a compaction stage of the lower soft rock layer, a tensile crack development stage of the middle hard rock layer, and a formation stage of through-going shear sliding zones along upper lithologic interfaces. Compared with conventional anchors, the ED&SC anchor improves the seismic performance of PACS by reducing the anchor axial force and rock lateral pressure. Graded energy dissipation of ED&SC anchor facilitates load redistribution, and enhances the cooperative bearing capacity and overall seismic resistance of the system. The findings provide technical support for the seismic design of bedding rock slopes in high-seismic-intensity regions.

Fractures are the primary pathways for fluid flow in rock masses, and they commonly occur as interconnected networks. Rock grouting is a process in which flowing water is displaced by grout. Since rock fracture networks are formed by a large number of crossed fractures, it is of great significance to study the displacement of grouts under the action of flowing water for designing effective grouting schemes. In this study, a rough orthogonal fracture model was established using three-dimensional reconstruction, and a laboratory visualization grouting test was conducted. We developed a numerical orthogonal fracture model using COMSOL Multiphysics to investigate the effects of fracture roughness, the grout-to-water flow rate ratio, and inlet-outlet configurations on the grout-water displacement process. After validation, the experimental and simulation results suggest that grout primarily fills well-connected channels. Grouting pressure rises rapidly after injection and stabilizes once most water is displaced. Efficient mixing at intersections yields more consistent grout volume fractions across branches. Displacement efficiency is governed by the dominant flow channels. If the conventional parallel-plate model is used, which ignores fracture surface roughness, the grouting pressure may be underestimated by more than 30%.

ObjectiveIn situations involving mountain floods, intense rainfall-induced erosion, and the breaching of clusters of landslide dams that lead to upstream soil and water loss, the inflow to landslide dams often becomes a sand-laden flow. Compared to clear water inflow, sand-laden flows produce more complex infiltration, erosion, and deposition processes, substantially influencing both the dam breaching process and the peak flow rates. This study investigates the mechanisms through which the sediment concentration and particle size of sand-laden flows influence dam breaching processes and examines the erosion-deposition dynamics and seepage-clogging phenomena induced by sand-laden flows during landslide dam breaching.MethodsFive sets of model experiments were conducted using a flume measuring 5 m in length and 0.4 m in width. Clear water inflow served as the control group, while the effects of different volumetric concentrations of sand-laden flow (0.01 and 0.03) and various maximum sediment sizes (0.006 5, 0.125 0, and 0.500 0 mm) on the dam breaching process were investigated. The primary method involved pre-experimental testing to adjust the composition of the sand-laden water flow, supplemented by thorough mixing in the water supply tank and the flow stabilization tank to achieve a stable and target sand concentration in the dam body area. The design of the landslide dam model was based on the range of dimensionless parameters related to dam height, dam volume, and reservoir volume derived from a database of landslide dam cases, and the material selection referenced empirical data from the 2008 Tangjiashan landslide dam. The experiments primarily used water level gauges to record the breach outflow process, while high-resolution cameras and grid systems monitored changes in the erosion rates of the landslide dams. Timed quantitative sampling methods tracked variations in sediment concentration. In addition, sampling, drying, and sieving techniques collected data on the moisture content and grain size distribution of the residual dam. The main steps of the experiment included material preparation, placement of the movable bed, layered construction of the dam body, execution of model tests, recording of experimental data, and subsequent sample analysis.Results and DiscussionsThe failure mode of the landslide dams in this series of experiments was consistently classified as overtopping failure, and the breaching process was primarily characterized by layered erosion accompanied by slope instability. The breach evolution process was divided into two stages: the initiation stage and the development stage. During the breach initiation stage, headward erosion predominated, and the dam height showed little noticeable reduction. The breach development stage was characterized by a rapid decrease in dam height, and peak flow rates were reached early in this stage. The water level in front of the dam reached its peak at the end of the breach initiation stage, whereas the peak flow rate occurred early in the breach development stage, and a secondary peak developed due to upstream slope instability that partially blocked the breach. The concentration of sand-laden flow in the dam area was inversely correlated with the breach flow rate, whereas the concentration measured at the end of the flume area showed a positive correlation. The mean particle size of the residual dam decreased longitudinally within the dam area and remained relatively stable in the downstream movable bed area. Comparative tests of sand-laden flows with different volumetric concentrations (Tests 1~3) showed that as the initial volumetric sand concentration increased from 0 to 0.03, the peak breach flow rate increased from 3.2 to 3.6 L/s, the time to peak increased from 76 to 90 s, the maximum water level in front of the dam increased from 24.6 to 26.9 cm, the residual dam height increased from 6.5 to 8.2 cm, and the final average breach width increased from 18.8 to 20.6 cm. The analysis indicated that higher sediment concentrations in the flow enhanced the erosion capacity during the breach development stage; however, the depositional layer formed during the process influenced the downward erosion rate during both the breach initiation stage and the late breach development stage. Comparative tests of sand-laden flows with different maximum particle sizes showed that as the maximum particle size increased from 0.006 5 to 0.500 0 mm, the peak breach flow rate slightly increased from 3.3 to 3.4 L/s, the time to peak increased from 79 to 90 s, and the maximum water level in front of the dam increased from 26.0 to 26.5 cm. The residual dam height remained relatively constant at approximately 7.5 cm, and the final average breach width also showed minimal variation at approximately 19.5 cm. The analysis indicated that the particle size of the sand-laden flow had minimal influence on the erosion rate of the landslide dam, mainly because the effect of particle size on the viscosity of the flow became negligible when particle sizes exceeded 0.1 mm. The comparative analysis of clear water inflow (Test 1) and sand-laden flows (Tests 2~5) showed that during the breach initiation stage and the late stage of breach development, low-velocity and high-concentration sand-laden flows generated strong depositional effects. These effects caused a slight reduction in erosion rates, an increase in the maximum water level in front of the dam, and a greater residual dam height. In contrast, during the early to middle stages of breach development, high-velocity sand-laden flows demonstrated greater erosive capacity and reduced deposition, which was reflected in increased erosion rates and higher peak outflow. In addition, sand-laden flows during the dam breaching process produced a pronounced clogging effect, which resulted in a multilayered structure within the dam body composed of depositional layers, retention layers, and original layers. The dense structure of the retention layer reduced the permeability of the sand-laden flow, lowered the position of the saturation zone on the breach slopes, and increased the scale of slope failures.ConclusionsThe experimental results indicate that, compared to clear water, the viscosity coefficient of sand-laden flow is higher, which enhances its erosive capability and also intensifies deposition. As the concentration increases, the viscosity of the sand-laden flow increases markedly, resulting in higher erosion rates, larger breach sizes, and greater peak outflow rates. As the particle size increases, the viscosity coefficient of the sand-laden flow exhibits negligible variation, leading to only minor changes in erosion rates and peak outflow rates. The seepage-clogging effect refers to the accumulation of sand particles within the surface layer of the dam body during the infiltration of sand-laden water flow, accompanied by the retention of these particles inside the dam. This retention layer decreases the infiltration rate, which lowers the saturated zone along the side slope of the breach. This change results in an increased scale of collapses on the side slope.

This study investigates non-Darcian flow to a well in confined aquifers, considering radial hydraulic conductivity variations. A stratified computational model based on the Izbash equation is developed and then solved by using the transformed differential quadrature method (TDQM). Initially, a linearization approximation approach is used to handle the continuity equation of groundwater flow based on Izbash's law. The Laplace transform is then applied, and the radial direction is discretized according to the discretization rules of the TDQM. After introducing the boundary and interlayer continuity conditions, an overall solution matrix is constructed. By solving the matrix equation and applying the inverse integral transform, the non-Darcian drawdown solution for the confined aquifer with variable hydraulic conductivity is derived. After several validations, case studies are designed to analyze the effects of various parameters on drawdown, including comparisons between stratified and equivalent models, sensitivity analysis of hydraulic conductivity and the non-Darcian coefficient across different radial zones, and the influence of wellbore skin.

This study presents the inaugural implementation of a physics-based digital twin (DT) system for artificial ground freezing (AGF) construction, demonstrated through Bangkok's pioneering tunnel rehabilitation project. The work is situated within the broader challenge of urban underground infrastructure under complex geological and environmental constraints, which increasingly demands high-precision and adaptive technologies. This project faces severe challenges due to complex and uneven strata, extremely high ground temperatures, and strict requirements for disturbance control of adjacent structures, making it difficult to rely solely on traditional numerical simulations. The developed physics-data integrated DT system addresses these limitations by synergizing finite element modeling with real-time data assimilation, establishing a dynamically optimized virtual representation of the freezing process. Through calibrated initial parameters from comprehensive in-situ sampling and laboratory tests, coupled with custom-developed bidirectional data interfaces, the system achieves accurate full-field predictions (MAE <0.6 degrees C) while maintaining computational efficiency. The successful field deployment validates the framework's capability to enhance decision-making accuracy, optimize freezing parameters operationally, and mitigate risks in complex urban geotechnical environments, marking a significant advancement for sustainable underground infrastructure repair.

As engineering projects extend into cold regions, there is a growing focus on the behavior of porous media under freeze-thaw (FT) cycles. Due to the presence of the water-ice phase transition, the behaviors of porous media are significantly more complex. In this study, a novel theoretical solution for layered porous media under FT conditions is presented, considering the water-ice phase transition. The governing equations for the thermo-hydro-mechanical (THM) coupling under FT conditions are established. Then, the differential equations are transformed and further converted into algebraic equations based on the transformed differential quadrature method. After incorporating the boundary conditions, a global matrix equation is formulated and solved. By virtue of the Hankel transform inversion, the time-dependent iterations of ice pressure and varying variables are achieved to accurately track the water-ice phase transition and the coupled THM behaviors. After verifying the proposed framework and solution, this study further analyzes the evolution of thermal-mechanical parameters, the impact of latent heat induced by water-ice phase transition, frost heave behaviors and the influence of layered characteristics. These findings may provide theoretical guidance and engineering insights for evaluating the performance of engineering structures in cold regions.

Rock joints are considered as a discontinuity between two continuous media. The presence of infilled joints influences the mechanical and hydraulic properties of joint rock. Understanding these properties is critical for assessing underground excavation safety, slope stability, and water inrush risk. However, few studies have analyzed the influence of high-water pressure on red-clay-infilled joints. Most previous shear-flow coupling studies have been limited to very low water pressures (<0.23 MPa) due to apparatus constraints. In this study, tests were conducted under higher water pressures of 0.4-0.8 MPa, simulating more realistic engineering conditions. In this study, both direct shear tests and shear-flow coupling tests are conducted to investigate the effects of surface roughness, normal stress, and water pressure on the shear stress, shear deformation, and hydraulic aperture of infilled joint rock. The results show that failure modes transform from frictional sliding failure to asperities cut-off failure with the increasing of joint roughness coefficient (JRC). Both peak and residual shear strength increase nonlinearly with the increasing of normal stress. The normal displacement shows pure compression or compression-dilatation behavior during the shear process and pure compression is likely to occur on the infilled joints with low JRC or high JRC with high normal stress. Water pressure does not change the overall failure type but reduces asperity engagement due to hydration-induced softening and mudification of the clay infill. As a result, peak shear stress decreases with increasing water pressure, and the maximum normal deformation exhibits a nonlinear "first-decrease-then-increase" trend. The hydraulic aperture evolves through three distinct stages-initial, rapid-growth, and stable. Higher water pressure enlarges the aperture and advances the onset of the rapid-growth stage, whereas greater normal stress suppresses aperture development. Joints with larger roughness tend to maintain relatively larger hydraulic apertures. These findings provide mechanistic insights into the hydromechanical behavior of clay-infilled joints under elevated water pressure and support the evaluation of stability and water-inrush risks in red-clay engineering environments.

Surface-wave (SW) and electrical resistivity tomography (ERT) surveys form a widely used and complementary geophysical pair for geological condition characterization, owing to their compatible acquisition geometries and contrasting sensitivity to stiffness and fluid–electrical pathways. However, the two methods respond to different physical properties and often produce inversion results that are difficult to reconcile, especially in heterogeneous soils and fractured rock masses. To obtain a more reliable characterization of shallow subsurface materials, we integrate SW and ERT results within a probabilistic modeling framework that quantifies and reconciles method-specific uncertainties. ERT data are inverted using ensemble Kalman inversion (EKI) with level-set parameterization to derive zoned resistivity structures and posterior uncertainty. Surface-wave dispersion curves are inverted using competitive particle swarm optimization (CPSO) to generate inversion ensembles of shear-wave velocity. Both inversions are transformed into voxel-wise probabilistic fields and integrated through an entropy-based weighting strategy that accounts for their relative reliability. Applied to the Enziping #2 landslide, the integrated probabilistic model delineates three principal material domains, including gravelly clay, weathered limestone, and a nodular limestone block. The block exhibits a low-resistivity but high-velocity signature that appears contradictory when ERT and SW are interpreted separately; the integrated result resolves this mismatch and identifies it as a relatively intact limestone fragment within the slide mass. This material configuration indicates that past slope movement occurred through a staged process involving block detachment and reassembly rather than a single translational slip surface. The embedded limestone block also modifies the internal mechanical and seepage structure of the slope, potentially creating stress concentrations or local deformation barriers that influence failure mode and effective strength parameters. Overall, this probabilistic modeling framework provides a quantitative linkage between geophysical responses and geological media, transforming independent single-method inversions into a unified probabilistic representation and advancing uncertainty-aware characterization in engineering geophysics and engineering geology.

China's southwestern region is characterised by active geological structures and frequent seismic activities. These conditions frequently trigger landslides that obstruct rivers and form landslide dams. The failure of these dams represents a significant threat to downstream populations, as exemplified by the breach of the Tangjiashan landslide dam during the Wenchuan earthquake. This study focuses on the overtopping breach type of landslide dams. It conducts large-scale experiments to investigate the impacts of various grading materials on the breach process. Furthermore, the DABA (Dam Breach Analysis) numerical simulation model is employed to conduct an in-depth analysis of the breach process in landslide dams. Based on the experimental and simulated results, the following characteristics of landslide dam breaches were analyzed. Under identical inflowing conditions, the peak discharge of the fine-grained dam is 1.6 times that of the widely-graded dam, which has a significantly higher susceptibility to breaching. Although both dams failed due to overtopping, their erosion mechanisms differed substantially. For the widely graded dam, coarse particles led to scouring and retrogressive erosion, significantly prolonging the breaching process. In contrast, the fine-grained dam primarily failed through layered scouring. The results show a high degree of consistency between the DABA numerical simulation outcomes and the large-scale experiment data, thus validating the model's reliability. The parameter sensitivity analysis revealed that breach development duration and peak discharge were significantly influenced by dam height, dam crest width, and initial water level. Scientific simulation models can more precisely predict the breach time and impact range of landslide dams, aiding in the development of more effective prevention methods.

Abstract Background Rock slopes containing weak interlayers are susceptible to seismic-induced sliding failure along the interlayer planes. This study aims to investigate the dynamic response of prestressed composite structures reinforced rock slopes containing weak interlayers. Based on a typical slope prototype in Ludian, Yunnan, a centrifugal model test was conducted at a geometric similarity ratio of 1:50, using four seismic intensity levels (2.50 –10.00 g) and three prestress levels for anchor cable (12 –120 N). Results There exists an evident dual-threshold effect of seismic intensity and prestress levels on the acceleration and displacement responses of slopes, with the critical thresholds being 5.00 g and 60 N, respectively. The dynamic response of the slope interior and surface exhibits remarkable elevation amplification, which peaks at the slope top: the amplification factor increases initially and then decreases with the seismic intensity and prestress level. The deformation of slope is predominantly concentrated at the slope top: the displacement shows two distinct variation trends: it increases rapidly at first followed by slow growth with rising seismic intensity, while it decreases sharply initially and then diminishes mildly with growing prestress. The peak bending moment of anti-slide piles and maximum axial force of anchor cables both increase with seismic intensity. The bending moment of piles is positively correlated with axial force of anchor cables under varying seismic intensity, whereas a negative correlation exists between the two parameters under different prestress levels. This indicates that the growth of seismic intensity aggravates damage of rock mass and weakens the stiffness of the slope system. By contrast, appropriately elevating the prestress of anchor cables can realize internal force redistribution, thereby strengthen the synergistic bearing performance of the prestressed composite structure. Conclusions The findings reveal key thresholds for seismic response and prestress regulation in pile-anchor reinforced bedding rock slopes. They provide experimental support and theoretical reference for the seismic design and safety evaluation of such composite supports in high-intensity seismic regions.

This study investigates non-Darcian flow to a partially penetrating well in confined aquifers, considering the stratification of the aquifer. A layered computational model is developed based on the transformed differential quadrature method (TDQM) and the Izbash equation. The continuity equation governing groundwater flow under Izbash’s law is first linearized through an approximation technique. The proposed solution is derived under the adopted linearization approximation and is therefore expected to provide the most reliable predictions during intermediate and late pumping periods. The Laplace transform is then applied, and the radial and vertical directions across multiple layers are discretized using the TDQM scheme, leading to a system of algebraic equations. By incorporating boundary conditions and enforcing inter-layer continuity, a global system matrix is constructed. Solving this matrix system and performing the inverse Laplace transform yield the non-Darcian drawdown solution for the multi-layered confined aquifers. After two validations, case studies are designed to analyze the effects of various parameters on drawdown, including non-Darcian index, comparisons between layered model and the equivalent homogeneous model, sensitivity analysis of hydraulic conductivities, effect of well partial penetration and the influence of well skin.

Landslides are complex geological hazards that require monitoring and predictive models capable of both high accuracy and physical interpretability. Traditional data-driven methods often treat monitoring sensors as isolated points, ignoring the spatial interactions that drive slope failure. This study proposes a domain knowledge-constrained dynamic spatio-temporal graph convolutional network (KD-STGCN) to monitor and predict slope displacement by explicitly modeling these spatial dependencies. The framework integrates geotechnical prior knowledge, specifically regarding traction, types of failure mechanisms and rainfall-induced lags, into a dynamic graph structure, ensuring the model adheres to physical laws. Application to a real-world bedding, controlled landslide reveals that the model successfully captures the progressive failure process. Analysis of the learned graph connections identifies a consistent 12-21-h time lag in the transmission of deformation from the slope toe to the mid-slope. Additionally, the model detects a rainfall-intensity-dependent response, where heavy rainfall triggers a rapid reaction within 12 h, while minor rainfall leads to a delayed response exceeding 48 h. A signif icant increase in the betweenness centrality of mid-slope nodes is also observed prior to acceleration, providing a quantifiable indicator of stress redistribution. Evaluation using data from 12 GNSS stations demonstrates that KD-STGCN achieves high predictive precision, with a Root Mean Square Error (RMSE) of 0.355 mm and an R2 of 0.996. The model maintains robust performance for prediction horizons ranging from 15 minutes to 12 h, with errors at the critical slope toe remaining below 1 mm. The one-year validation further shows that the framework remains effective under seasonally varying conditions. These results confirm that integrating domain knowledge with deep learning not only improves prediction accuracy but also provides interpretable insights into deformation patterns, offering a practical and reliable tool for landslide monitoring.

Reliable analytical models can serve as robust tools for assessing injection-induced seismicity. Existing analytical models are largely restricted to isotropic reservoirs and therefore do not capture the poroelastic anisotropy typical of layered sedimentary formations. Here, we derive a closed-form analytical solution for injection-induced poroelastic fields in a transversely isotropic reservoir intersected by a displaced fault, based on Eshelby's inclusion theory and orthotropic Green's functions. The solution recovers existing isotropic solutions as limiting cases and agrees well with finite-element simulations. Parametric and lithology-based analyses show that within the investigated parameter ranges and representative lithologies, elastic anisotropy has a comparatively limited influence on the predicted reactivation response, whereas the directional Biot's coefficients exert a stronger control on fault reactivation potential and pre-slip length. Their influence is also geometry dependent, with the vertical Biot's coefficient being more important for gently dipping faults and the horizontal Biot's coefficient being more important for steeply dipping faults. Comparative analysis of the five representative lithologies further shows that the clay-rich cases examined here exhibit higher fault-reactivation potential, owing to the combined effects of strong poroelastic effect and relatively low frictional resistance. These results collectively indicate that neglecting poroelastic anisotropy may lead to underestimation of the predicted fault-reactivation potential, particularly for mechanically weak, clay-rich parameter sets under the conditions considered here. This analytical solution provides a rapid and physically transparent tool for first-order assessment of fault reactivation in injection-related subsurface operations.

Rockslides in valley regions are influenced by multiple factors such as terrain of the valley, river water depth, strength of the sliding mass and sliding surface friction. The fragmentation and sliding behaviour of rock masses play a dominant role in subsequent blocking valley and wave generation processes. Presently, there are limited methods for three-dimensional (3D) simulations that consider actual topography and account for the entire process of rupture, contact, sliding, and induced waves in valley areas. The underlying mechanisms for the sliding failure and the induced waves remain unclear. We propose an improved SPH method to simulate the Geohazard chain of the Baige rockslide event, considering the influences of river water depth, sliding surface friction coefficient and sliding mass strength. Numerical results indicate that the 3CDSPH method, based on an elastic-brittle constitutive law and a damage-based virtual bond method, effectively reproduces the transition of rock masses from continuum to fragmented states. The improved kernel function facilitates identification and realization of block contact behaviour, and an adaptive bounding technique addresses interactions among the sliding mass, sliding bed and river water. Additionally, we introduce a unique framework for realizing fluid-solid interaction (FSI) considering both damaged and intact rocks. The 3CDSPH method effectively captures the complete process of fragmented sliding in the Baige rockslide, and the obtained peak velocity, extent of rockslide accumulation, river erosion height, and flow velocity are comparable to recorded or reported results. A comparative analysis outlines distinct wave generation mechanisms controlled by the friction coefficient, rock strength and water depth.

Under global warming, increasingly severe freeze-thaw cycles in cold regions trigger frequent rockslides, posing significant threats to infrastructure safety. This paper presents an engineering-oriented thermal-mechanicaldamage coupled smoothed particle hydrodynamics (SPH) method to simulate the progressive failure of freezethaw-induced rockslides, prioritizing practical applications over theoretical complexity. The freeze-thaw evolution within fractured rock masses is analyzed by integrating phase transition with porous media heat transfer. Frost heave pressure and thermal stress are incorporated into the Cauchy stress equation, effectively coupling the frost heave and thaw settlement between rock fractures and the intact matrix. The proposed method is rigorously validated and applied to investigate the failure mechanisms of jointed rock slopes on the Qinghai-Tibet Plateau under various engineering conditions: number of freeze-thaw cycles, temperature range, joint dip angles, frost heave coefficient (beta f), and elastic modulus (E). Results demonstrate that the improved SPH framework successfully captures the complete failure process, including thermal thaw weakening, frost-heave cracking, icewedge propagation, sliding-toppling failure, and large deformation. The joint dip angle, temperature amplitude, freeze-thaw cycling mode, beta f, and E collectively control the failure mode transition, instability timing, damage extent, and sliding magnitude. Notably, rectangular freeze-thaw cycles induce the most severe damage, while the synergistic effect of beta f and E shows a linear correlation with slope displacement and damage intensity. This work overcomes key limitations of traditional numerical methods in simulating freeze-thaw rockslide mechanisms, providing a reliable and practical tool for geohazard risk assessment and disaster mitigation in critical cold-region engineering projects.

Rock slope instability poses significant risks to infrastructure and public safety, particularly in layered geological settings. This study introduces a resonance-based detection method for identifying sliding surfaces in layered rock slopes, and establishes practical criteria for guided wave configuration through numerical analysis of energy and dispersion behavior. Numerical simulations in both P-SV and SH modes were conducted to investigate how signal energy and dispersion respond to changes in the thickness-to-wavelength ratio (R_ws) and impedance contrast. The results indicate that as R_ws increases, signal energy rises to a peak and then gradually declines, while dispersion first intensifies and later weakens. These trends reflect shifting modal dominance within the waveguide. To balance these competing effects, a compromise is made at R_ws = 2 in P-SV mode and R_ws =1 in SH mode, where the signal retains relatively high energy with limited dispersion—defining practical optimal conditions for detection. Impedance contrast further modulates signal quality: in P-SV mode, moderate contrasts (1.2–1.5) produce favorable pulse-like signals, while SH mode benefits from increased contrast across the tested range. This behavior is attributed to changes in guided wave mode composition; fundamental modes dominate at intermediate R_ws, while higher-order or leaky modes emerge at larger values, increasing dispersion and reducing signal coherence. The method is validated using a synthetic model of the Hongshiyan landslide, where under optimal conditions, sliding surfaces in three weak layers are identified with a mean depth error below 10%. The resonance phenomenon is also observed in cross-hole simulations, demonstrating the method’s potential for broader geophysical applications.