Cutoff walls are essential engineering structures that mitigate environmental risks at contaminated sites by restricting pollutant migration alongside groundwater flow. This study developed bentonite-geopolymer cutoff wall materials utilizing calcium bentonite (CaB) and modified calcium bentonite (mCaB). A series of macro- and micro-level experiments were conducted to evaluate their fundamental engineering properties and durability under dry-wet cycles. The mechanism by which CaB improves durability was clarified, and performance differences between CaB and mCaB were explained. Results indicated that increasing the bentonite content elevated hydraulic conductivity while reducing unconfined compressive strength in both CaB- and mCaB-based systems; however, all met the design requirements. The incorporation of 3% bentonite significantly enhanced durability during dry-wet cycles. After 10 cycles, the mCaB-geopolymer exceeded the hydraulic conductivity limit (1×10^⁻8 m/s), whereas the CaB-geopolymer still satisfied the design requirements. Bentonite addition increased water demand and altered the geopolymerization process, affecting material behavior. During dry-wet cycles, drying induced shrinkage and cracking near bentonite particles, while rehydration promoted swelling that hindered crack propagation. Compared to mCaB, CaB caused less debonding from the matrix due to its lower swelling capacity, thereby maintaining structural integrity and offering superior durability under dry-wet cycles.

Transversely isotropic loess undergoes dehumidification and shrinkage when subjected to vertical stress, resulting in changes to its water-retention characteristics and mechanical behavior. Improper management of this phenomenon can lead to substantial engineering losses. However, no theoretical models have been reported that investigate the impact of dehumidification and shrinkage on water-retention characteristics under vertical stress. This study utilized a pressure plate apparatus to perform soil-water characteristic curve (SWCC) tests on transversely isotropic loess with different initial dry densities. Water content w and volumetric changes were measured after stabilization at each suction level. The results indicate that, except for soil samples with lower initial dry density, the θ-s (θ is volumetric water content) curve displayed a slight upward trend under high vertical stress and low suction, while the water content of other samples generally decreased with increasing suction. During the suction increase, except for soil samples with very low initial dry density, the SWCCs of samples with the same initial dry density but different vertical stresses intersected. As suction increases to a certain value, higher vertical stress results in larger values of w, θ, and saturation S_r for the soil sample. Soil samples with higher initial dry densities exhibited reduced sensitivity to variations in vertical stress within their SWCCs. The volumetric strain of the soil sample increases with both increasing vertical stress and suction. By integrating generalized Hooke’s law with the Fredlund-Xing model, we established a volumetric strain model that accounts for coupled vertical stress-suction effects and a modified SWCC model for volume changes. Both models effectively captured the evolution of volumetric strain and saturation in transversely isotropic loess during dehumidification and shrinkage under varying vertical stresses. This research not only advances the theoretical framework of unsaturated soil SWCC models, but also offers critical insights for ensuring the safety of natural stratified foundations and compacted fill engineering projects.

To address the challenges of data-scarce sample size, sparse spatial distribution, and inadequate physical consistency in predicting marine clay parameters, we developed a Gaussian process regression (GPR) model that integrates a physics-guided augmentation(PGA) algorithm with a weighted kernel strategy. In the proposed PGA-GPR model, physical knowledge, including the effective stress principle, the upper bound of shear strength, and the overconsolidation ratio, is incorporated together with a multi-kernel weighting mechanism. This design improves the model’s ability to capture nonlinear behavior and ensures physical consistency. Using data on Norwegian marine clays from the TC304b database, we validated the model’s ability to predict marine clay parameters as a function of depth. The results show that, under sparse-sample conditions, PGA-GPR increases determination coefficient R² by 17%–53% relative to conventional machine learning models. It also provides higher prediction accuracy and more stable performance. Moreover, compared with the stratified random field model previously proposed by the authors, PGA-GPR more effectively captures depth-dependent variations in the overconsolidation state of marine clays, demonstrating both predictive effectiveness and physical consistency. Additionally, PGA-GPR provides reliable prediction intervals, with at least 84% of the measured values for each soil parameter falling within the 95% confidence interval. These results suggest that the model offers a promising methodology for geotechnical engineering modeling in data-scarce scenarios.

Heavy rainfall events frequently occur in natural environments. To enhance landfill operation and management, it is essential to investigate the water infiltration characteristics of the landfill soil cover and the associated slope stability under heavy rainfall conditions. Although relevant analytical studies have been reported, they have limitations, such as the limitation to account for the continuous variation of heavy rainfall rates over time. Therefore, on the basis of the previous researches, this paper incorporates the time-varying feature of heavy rainfall rate and the arbitrary initial water content distribution form, and employs the joint methods of variable substitution, separation of variables, and series transformation to obtain the corresponding analytical solutions for water infiltration. Subsequently, the developed analytical solution is validated by comparing it with existing analytical and corresponding numerical solutions. Finally, the analytical solutions are applied to analyze the effects of heavy rainfall patterns and initial water content distribution forms on the bottom leakage and slope stability of the landfill soil cover. The results indicate that among the four heavy rainfall patterns with equal total rainfall, the “pre-peak” rainfall pattern exhibits the highest bottom leakage rate (Q_b) and cumulative leakage CQ_b, but the lowest factor of safety F_s for slope stability assessment. Conversely, the “post-peak” rainfall pattern shows opposite trends, while intermediate results are observed for the other rainfall patterns. Among the four initial water content distribution forms with equal total water storage, Q_b and CQ_b are the highest in the distribution form with low water content at the top and high water content at the bottom. However, in this distribution, F_s is the lowest after a period of heavy rainfall infiltration. Conversely, Q_b and CQ_b are the lowest in the distribution form with high water content at the top and low water content at the bottom, while the corresponding F_s is highest. Overall, this conducted analytical study offers guidance for the application and design of landfill soil covers.

The strength of rock material is composed of cohesive strength and friction strength, with residual friction strength being dependent on the confining pressure level. Based on experimental data from rock materials subjected to varying confining pressures and freeze-thaw cycles, we determined the statistical damage model parameters associated with confining pressures. The microelement strength of rock, measured directly by axial strain during the post-peak strain softening stage was assessed, revealing that the final value of the evolution of statistical damage variables in the residual damage stage is less than 1. Utilizing the Lemaitre strain equivalence assumption, we proposed a strain softening constitutive model to characterize the stress drop in rock materials. This model converts the peak stress of rock into nominal stress using residual damage variables. By comparing the model with experimental data, we verified its validity under various confining pressures and low freeze-thaw cycles. Using the model parameters and peak strain test data from rock materials under varying confining pressures and freeze-thaw cycles, we obtained the strain lag factor that characterizes the residual strain lagging behind the peak strain. We also determined the stress drop rate of rock material, expressed by the strain lag factor during the strain softening stage. Additionally, we identified the range of increased brittleness and plasticity of rock materials during this stage and verified the relationship between Weibull shape parameters and fractal dimensions concerning the failure probability of rock microelements under triaxial stress states.

Gravelly soils formed at the base of mountains exhibit a coarse-grained orientation due to multi-stage water scouring, complicating the understanding of their mechanical behavior. Existing research indicates a strong correlation between coarse-grained orientation and the mechanical properties of gravelly soils; however, a systematic understanding of these effects remains lacking. To clarify the effect of coarse-grained orientation, we considered typical field gravelly soils with a coarse-grain content of 30% and cohesion in the matrix soil. A series of large-scale indoor triaxial tests was conducted to analyze the nonlinear variation of shear strength and its parameters. The results indicated that (1) the coarse-grained oriented structure attenuated the shear strength of clayey matrix gravelly soil by 5.99% to 24.88%. When the orientation angle of coarse grains is no more than 45°, the shear strength of gravelly soil under various confining pressures decreases most significantly at an angle of 0°, and the attenuation effect of coarse particle orientation weakens as confining pressure increases. When the orientation angle exceeds 45°, the influence of coarse-grained orientation becomes negligible. (2) The coarse-grained oriented structure attenuateds the shear strength of sandy matrix gravelly soil by 11.84% to 20.46%. When the orientation angle is less than 45°, the shear strength decreases almost linearly, reaching its minimum at 45° under various confining pressures. When the orientation angle exceeds 45°, the shear strength increases with the angle. (3) By examining the development of the main shear plane and the rotation of coarse particles, we analyzed the effect of coarse-grained directional structure on the shear strength of gravelly soil. It was found that the shear strength of coarse-grained directional gravelly soil in cohesive and sandy matrices is primarily influenced by the rotation of coarse particles and the development of the main shear plane, respectively. Furthermore, the influence of coarse-grained directional structure on sandy matrix gravelly soil was found to be more significant than on cohesive matrix gravelly soil. Additionally, we analyzed the reasons for the differences in matrix regulation. We modified the Mohr-Coulomb equations for gravelly soils with coarse-grained oriented structures under different matrix conditions by introducing orientation angles. The conclusions of this study will serve as a reference for the scientific assessment of stability in mountain front slopes or sites.

To investigate the instability and failure of deep geological structural rocks under disturbed stress, which reduces the stability of surrounding rocks, we conducted a granite failure experiment involving real-time high-temperature biaxial cyclic loading and unloading at 250 ℃. This study examines the mechanical damage, energy evolution, and acoustic emission (AE) signal characteristics of granite subjected to cyclic loading and unloading with equal amplitude. The results are as follows: (1) As the stress level of cyclic loading and unloading disturbances increases, both the elastic modulus and irreversible strain of granite show an upward trend under varying lateral stresses. When the lateral stresses are 20, 40, 60 MPa, and 80 MPa, the elastic modulus increases by 7.73, 9.07, 10.23 and 9.87 GPa, respectively, while the irreversible strain increases by 1.2×10⁻³, 0.2×10⁻³, 0.4×10⁻³, and 0.5×10⁻³, respectively. The energy of the rock specimens exhibits a nonlinear growth trend, accompanied by a decrease in the proportion of dissipated energy. Specifically, at lateral stresses of 20, 40, 60 and 80 MPa, the proportion of dissipated energy decreases by 16.7%, 14.8%, 13.9%, and 11.9%, respectively, indicating that most of the input energy is stored as elastic energy. (2) The peak strength of granite increases with increasing lateral stress. At lateral stresses of 20, 40, 60, and 80 MPa, the corresponding peak strengths are 230.24, 263.81, 272.42, and 297.21 MPa, respectively. The elastic modulus of the rock also increases from 14.9 GPa to 15.8 GPa accordingly. Meanwhile, the irreversible strain decreases from approximately 3.3×10⁻³ to about 1.4×10⁻³. Regarding energy, the proportion of dissipated energy within the same loading interval decreases by 2.0% to 7.5%. (3) As confining pressure increases, the AE ringing counts significantly decrease, with peak counts of 29 383, 28 467, 17 539, and 9 436, respectively, and the frequency of AE ringing counts also declines. Under the same confining pressure, as cyclic loading and unloading progress, there is a sharp increase in AE ringing counts at failure. The b-value initially increases and then decreases, reaching its lowest value at failure, typically ranging between 4 and 7. The cumulative AE energy increases, with rapid growth occurring near failure. This research offers valuable insights into the mechanical properties and damage behaviors of deep geological structural rocks.

The interfacial properties of shale reservoirs significantly influence the three-dimensional propagation behavior of hydraulic fractures. This study prepares artificial shale specimens with varying interfacial strengths using an interlayer interval casting method and conducts true triaxial hydraulic fracturing tests. The center deviation index (CDI) and radial non-uniformity (RNU) are established to quantitatively characterize the three-dimensional geometric features of fractures. By analyzing injection pressure curves and acoustic emission parameters, this study investigates the influence of interfacial strength on hydraulic fracture propagation. The results demonstrate that interfaces induce deflection effects in hydraulic fractures, causing them to twist or propagate along these interfaces, resulting in asymmetric three-dimensional morphologies with noticeable shifts toward the interfaces. Under a normal stress ofσ_z=15 MPa, as the interfacial cohesion and the internal friction angle decrease, the calculated interfacial shear strength decreases from 19.9 MPa to 10.1 MPa. Consequently, the fracture morphology transitions sequentially, exhibiting characteristics of V-shaped penetration, Y-shaped branching, and ultimately T-shaped or H-shaped capture. The RNU value increases from 0.36 to 1.06, while the CDI value decreases from 0.42 to 0.29, indicating that lower interfacial strength restricts outward fracture propagation. Interfacial strength governs both the energy release modes and fluid migration pathways. Weaker interfaces reduce the initiation pressure and promote large-scale fluid loss along these interfaces, creating favorable conditions for complex fracture network formation. A reduction in interfacial shear strength significantly alters the fracture failure mode, where high-strength interface conditions predominantly produce tensile fractures, while low-strength interfaces induce a transition to a composite tensile-shear failure mechanism.

Rock masses in cold regions are consistently subjected to a complex thermal-hydraulic-mechanical (THM) environment. The engineering behavior of these rock masses and associated geological disasters are closely linked to the coupled THM effects. A THM coupling creep test on freeze-thaw sandstone was conducted for rock slopes in open-pit mines in cold regions, simulating the complex freeze-thaw environment that the rock mass experiences. This study examined the time-dependent deformation and failure characteristics of freeze-thaw rock masses under THM coupling. The results indicate that: 1) Under the influence of THM coupling, a low-frequency periodic stress occurs in the sandstone, varying with the temperature cycle. This stress is the primary cause of creep damage accumulation and fatigue failure in the sandstone. 2) The creep process of freeze-thaw sandstone can be categorized into four stages: freezing stage, steady-state creep during freezing, thawing shrinkage stage, and steady-state creep post-thawing. During the freezing expansion stage, deformation primarily involves expansion strain, whereas in the thawing shrinkage stage, it predominantly involves compression strain. 3) An interaction exists between the freeze-thaw and seepage environments during the creep process of sandstone. Seepage replenishes water in the sandstone after thawing, intensifying freeze-thaw damage. Conversely, freeze-thaw conditions increase the porosity and pore connectivity of the rock, thereby enhancing the influence of seepage on the creep rupture of sandstone. This interaction creates a vicious cycle, exacerbating the creep failure of the sandstone. 4) During the creep process of freeze-thaw sandstone under THM coupling, a strong correlation exists between strain and seepage. The permeability of sandstone increases with cold shrinkage strain during the freezing process, while the phase change of pore water induces freeze swelling strain, subsequently reducing permeability. During thawing, permeability rises with thaw shrinkage strain due to the melting of pore ice. The permeability shows a gradually decreasing trend with the compression strain. This study reveals the creep and seepage characteristics of rock masses in cold regions under low-temperature THM coupling, providing a crucial scientific basis for the stability evaluation and disaster prevention and control of rock mass engineering in these areas.

Variations in water pressure affect both the long-term and short-term effective stress in rock masses, thereby influencing ultrasonic wave propagation. Investigating the effects of cyclic water pressure loading on the frequency-domain characteristics of ultrasonic waves facilitates the inversion of damage evolution in deep rock masses under these conditions. Using a self-developed ultrasonic test system designed for rocks under high water pressure and ground stress, we conducted ultrasonic wave propagation tests on red sandstone subjected to cyclic loading and unloading with constant amplitude water pressure. We performed a Fourier transform on the ultrasonic head wave data and analyzed the variation characteristics of the ultrasonic wave frequency spectrum amplitudes in relation to the water pressure cycle. We defined the spectral energy transport coefficient and analyzed its variation, along with the centroid frequency and quality factor, during constant amplitude water pressure cycling. Additionally, we constructed an empirical model for the attenuation of ultrasonic frequency-domain parameters in rock. Results indicate that, under constant amplitude water pressure cycling, both the spectral area and centroid frequency show an overall downward trend as the number of cycles increases. The spectral energy transport coefficient decreases linearly as the cycle number increases. As the number of constant amplitude water pressure cycles increases, the quality factor Q decreases rapidly at lower water pressures, while it decreases more slowly at higher water pressures. These research findings are valuable for understanding the damage to rock masses in deep high water pressure environments and provide a reference for the inversion of such environments.

Carbonic anhydrase (CA) is a ubiquitous enzyme present in nearly all living organisms except fungi. It is non-toxic, environmentally benign, cost-effective, and already produced at industrial scale, with widespread applications in the food and beverage industries. CA dramatically accelerates the hydration of CO₂ to generate carbonate ions (CO₃²⁻), enhancing the reaction rate by approximately 10⁸-fold. In this study, CA is employed to improve the biocarbonation process of reactive magnesia cement (RMC) for sustainable soil stabilization. By catalyzing the carbonation reactions of RMC, CA promotes greater CO₂ sequestration, increases the degree of carbonation, and facilitates the formation of hydrated magnesium carbonates (HMCs)—specifically hydromagnesite and nesquehonite—which act as cementing agents between soil particles, thereby achieving green, low-cost, and highly efficient strength enhancement. The key findings are as follows: (1) CA effectively promotes the carbonation of Mg(OH)₂ (formed from RMC hydration), significantly increasing the precipitation of hydromagnesite and nesquehonite, leading to a strength improvement of up to 74.6%. (2) The beneficial effects of CA on both strength development and carbonation degree intensify with prolonged curing time, with enhancement rates reaching 42.6% in strength and 153.7% in carbonation degree over the testing period. (3) Microstructural analyses reveal that the CA-catalyzed formation of HMCs modifies the soil pore structure by transforming larger intra-aggregate macropores into finer interparticle pores, resulting in a denser and more compact soil matrix. (4) A notable synergistic mineralization effect exists between urease and CA during RMC carbonation, where CA incorporation enhances biomineralization kinetics and biological mineral transport processes, substantially accelerating the overall bio-carbonation reaction rate and increasing carbonate precipitation. The CA-enhanced RMC bio-carbonation technology proposed in this study demonstrates strong potential and favorable conditions for practical field applications.

This study investigates the distribution characteristics and influencing factors of water pressure outside tunnel with external drainage. The semi-infinite seepage region is transformed into a rectangular area using conformal transformation and is divided into four sub-regions based on the boundary conditions. The analytical solution for the seepage field of the external drainage tunnel, accounting for the effect of the grouted circle at any burial depth, is derived using the method of separation of variables. The water pressure outside the lining and the drainage volume calculated from the analytical solution are compared with those obtained from the ABAQUS numerical solution and the existing mirror image method to validate the accuracy of the analytical solution. The influence of parameters, such as the permeability coefficient of the grouted circle, on the effectiveness of water pressure reduction using the extracorporeal drainage method is analyzed and discussed. The results indicate that the external drainage method significantly reduces water pressure at the tunnel invert; however, the pressure reduction effect on the arch and side wall areas is minimal. Increasing the permeability coefficient of the grouted circle and the radius of the drainage hole enhances the pressure reduction effect but also increases drainage volume. This drainage method reliably and effectively reduces water pressure at the tunnel crown across various burial depths. The findings of this study provide theoretical support for the design of drainage systems and the assessment of water pressure reduction effectiveness.

 Soft soil has been a major problem in the northern part of Java for the last decade, and several areas have been improved using the preloading method. In Indonesia, the improvement of soft soil using this method has already been regulated in several codes, such as SNI 8460:2017 and Geotechnical Manual series 4. However, these codes did not mention the effects of creep on post-settlement. In addition to creep, several factors influence the amount of post-settlement during the operational period, such as the thickness of the soft soil, load ratio, soil compression ratio, and the drain spacing and pattern. Larger spacing or pattern, higher compression ratio, greater creep coefficient, and increased soft soil thickness induce more post-settlement. In contrast, a higher load ratio resulted in less post-settlement. It was discovered that the load ratio of 1.20 stated in Malaysia standard SNI 8460:2017 did not meet the requirement of a maximum yearly settlement of 20 mm as specified in Geotechnical Manual series 4. This research showed that with and without creep, the load ratio required should be in the range of 1.30 to 1.50, with an average value of 1.375. Furthermore, this study proposed a new coefficient, load ratio coefficient C_LR, that accounts for various factors influencing post-settlement. The proposed coefficient can be utilized along with a period of interest to estimate the post-settlement due to creep. It was also observed that the load ratio heavily affects the post-settlement.

To address the engineering challenges posed by organic-rich soils and industrial solid waste and to promote their resource utilization in geotechnical engineering, this study adopts a solidification method using alkaline solid waste combined with cement. Through unconfined compressive strength, flowability and shrinkage tests, as well as microscopic charaterization techniques including X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), nuclear magnetic resonance (NMR), and scanning electron microscopy (SEM), the mechanical properties, microstructural evolution, and chemical reaction mechanisms of alkaline solid waste-reinforced cementitious flowable solidification in organic-rich soils are investigated. The results indicate that as the fulvic acid content in soil increases, the strength of the stabilized soil gradually decreases while its fluidity continuously increases. In contrast, the fluidity of stabilized soil initially increases and then decreases with rising humic acid content. Incorporating alkaline solid waste significantly enhances strength and reduces volumetric shrinkage. During the 28 day curing period, the strength influence hierarchy was: alkali residue ≥cement ≥naphthalene-based superplasticizer ≥fly ash ≥red mud ≥carbide slagging. In the 60 day curing period, the hierarchy changed to: cement ≥alkali residue ≥naphthalene-based superplasticizer ≥red mud ≥fly ash ≥carbide slagging. Microstructural analyses confirm that hydroxide ions (OH⁻) from alkaline wastes neutralize hydrogen ions (H⁺) released from organic matter, promoting the formation of C-S-H and C-A-H gels. This process improves soil particle cementation and refines pore structure. A novel microscopic mechanism model to elucidates the interactions between organic matter and alkaline waste is established. This model provides theoretical foundations for the sustainable recycling of problematic soils and industrial solid wastes.

During sustained debris flow impacts on water bodies, only a portion of debris particles governs the formation of maximum impulse wave amplitudes. Accurately determining the volume of these critical particles is of significant scientific and engineering value for disaster prevention and mitigation. This study utilizes a two-dimensional physical model to conduct simulation experiments on debris flow and impulse waves. By varying factors such as the debris flow slope gradient, movement path slope, water depth, debris flow initiation elevation, debris flow volume, and particle size, we investigate the mechanism of debris flow-wave interaction under multiple conditions and derive a prediction formula for the maximum first-wave amplitude based on effective wave-making volume. Key findings include: 1) In debris flow-impulse wave processes, the portion of debris that enters the water before the impulse wave propagates beyond the range of water body influenced by the debris flow constitutes the effective wave-making volume, which is the primary factor determining the amplitude of the first wave in the debris flow-wave process.     2) Experimental results demonstrate that the mobility of the debris flow significantly influences the proportion of the effective wave-making volume. When slope gradients are moderate to high inclination angle and is not less than the movement path slope, the debris flow exhibits high mobility, and the proportion of effective wave-making volume reaches 50% to 100%. Conversely, at low inclination angle and is less than the movement path slope, the debris flow mobility is lower, and the proportion of effective wave-making volume is only 20% to 38%. Notably, scenarios with smaller total volumes but higher effective proportions exhibit larger maximum first-wave amplitudes compared to scenarios with larger total debris volumes but lower effective proportions. 3) A dimensionless parameter k is proposed to characterize applicability, When the value of k is within the range of 0.10 to 2.59, the derived calculation formula for the effective wave-making volume and the wave amplitude prediction formula demonstrate strong applicability. These findings provide a theoretical foundation for understanding disaster mechanisms in debris flow-impulse wave hazard chains and for designing protective engineering measures.

The unloading pile-sheet retaining wall is a new type of support/retaining for embankment slopes and has demonstrated excellent performance in engineering applications. However, its mechanical behavior and operational mechanisms are still not fully understood. This study conducted model tests on unloading piles and cantilever piles. Backfilling was conducted in four stages: 30 cm for the first three layers and 10 cm for the final one. The tests focused on the evolution of earth pressure, internal forces, and deformation in both pile types. The results show that: 1) Upon completion of backfilling, the horizontal displacement at the top of the cantilever pile reaches 81.76 mm, which is 5.45 times that of the unloading pile (14.99 mm). The maximum earth pressure on the unloading pile is 10.08 kPa, accounting for 66.40% of the 15.18 kPa recorded on the cantilever pile. The unloading effect alters the distribution pattern and magnitude of earth pressure. 2) The bending moment distributions differ significantly. The cantilever pile exhibits a “fish-belly” pattern with a maximum moment of 115.8 N·m. In contrast, the unloading pile shows an “S-shaped” profile, featuring a pronounced point of contraflexure at the unloading platform and a maximum negative moment of −60.99 N·m. 3) Incorporating an unloading platform effectively reduces earth pressure and enhances the anti-overturning moment. These effects jointly improve sliding resistance and overall structural stability. These findings offer theoretical insights and technical guidance for the practical implementation of unloading pile-sheet retaining walls.

To address the issue of channel-type loose deposits undergoing simultaneous vertical infiltration and lateral runoff during rainfall, which significantly affects their stability and failure modes, a prediction model for the infiltration-wetting front depth of loose deposits under multi-directional runoff influence (multi-directional catchment Green-Ampt, abbreviated as MCGA) was established based on the theoretical framework of the classic Green-Ampt (referred to as GA) model, incorporating the influence coefficient of lateral catchment and the slope runoff coefficient. To validate the reliability and applicability of the proposed model, we designed and conducted physical model experiments to simulate multi-directional infiltration into loose deposits under coupled multi-factor interactions. Systematically simulating infiltration processes under varying conditions of infiltration duration, vertical rainfall intensity, lateral inflow angle, and flow rate, the migration path and depth dynamics of the wetting front were monitored in real-time via data acquisition and observation systems. Computational results from the proposed model and the classical GA model were then compared with experimental measurements. The results indicate that, compared to the GA model, which disregards multi-directional runoff effects, the MCGA model shows superior agreement between predicted wetting front depths and experimental measurements across multiple scenarios. The mean absolute percentage error (MAPE) of the MCGA model consistently falls below 10%, demonstrating significantly enhanced predictive accuracy. Further parameter analysis indicates that the model is applicable to infiltration scenarios where lateral inflow angles range from 15° to 60°, and lateral inflow intensity does not exceed vertical rainfall intensity. These findings provide a theoretical reference for deepening the understanding of unsaturated infiltration patterns, failure mechanisms, and disaster risk assessment in loose deposits subjected to multi-directional inflow.

In recent years, numerous giant landslides have been identified in the tectonic suture zones of the Qinghai–Tibet Plateau, and their occurrence has been shown to be closely associated with clay-altered rock masses. Using the Baige Landslide in the Jinsha River tectonic suture zone as the study background, this study focuses on rock masses containing altered clay interlayers. On the basis of fully considering key factors such as rock wall strength, structural plane undulation, clay filling degree and water content, a series of cyclic shear tests was conducted on the structural planes. Using methods such as 3D laser scanning, scanning electron microscopy (SEM), and two-dimensional particle flow grogram PFC2D, the mechanisms by which altered clay interlayers affect the strength of rock mass structural planes under different conditions were comprehensively investigated. The results indicate the following: 1) Shear deformation and failure of the structural plane containing the altered clay interlayer proceed through four stages: compaction and slip, crack initiation and propagation, mixed wear of the altered clay and the asperity surface, and final shear penetration of the structural plane. 2) The principal factors controlling the behavior of the structural plane containing the altered clay interlayer are the filling degree and water content of the altered clay, followed by rock wall strength and structural plane roughness. 3) As the filling degree of the altered clay increases, the peak strength of the structural plane decreases rapidly at first and then gradually stabilizes, while the mechanical behavior becomes increasingly dominated by the clay interlayer; the maximum reduction reaches 82.6%. 4) Based on the experimental data and numerical simulation results, a formula for estimating the shear strength of structural planes containing altered clay interlayers is proposed. These findings provide a theoretical basis for determining design parameters for similar landslide mitigation projects.

To investigate the response patterns of temperature, moisture, deformation, and stress fields in geocell-reinforced soil retaining walls subjected to freeze-thaw cycles, a model test was conducted based on a new project at Hashilegen Daban along the G217 Dushanzi-Kuqa Highway. A coupled hydrothermal-mechanical numerical model for the geocell-reinforced retaining wall was developed using the secondary development module in COMSOL. This study analyzed the effects of freeze-thaw cycles on the internal temperature field, moisture distribution, and stress-strain behavior of geocells post-construction. Experimental results were compared with simulation results to validate the findings. The findings indicate that the temperature field exhibits a curvilinear pattern influenced by freeze-thaw cycles, showing notable hysteresis with increasing depth. Temperature gradients induce moisture migration toward the freezing front, resulting in the formation of a frozen layer of specific thickness and moisture accumulation at the wall toe. Combined moisture accumulation and phase-change expansion drive asymmetric frost heave and thaw settlement, with the most significant displacement occurring from one-third of the wall height to the top. The strain distribution exhibits a convex nonlinear pattern, indicating that the middle-lower and near-surface zones become mechanically vulnerable. Geocells withstand frost heave pressure during cold seasons and earth pressure during warm seasons, regulating stress distribution through bidirectional restraint, thereby effectively mitigating wall deterioration.

Traditional slope reinforcement methods face challenges, including high time costs, limited dynamic adaptability, and inadequate capabilities for optimizing and comparing schemes in complex geological conditions. This study reviews the developmental context and key aspects of intelligent self-matching reinforcement technology, which has evolved from traditional methods in the modern era. Research analysis reveals significant advancements in the intelligent development of slope stability calculations and evaluations, the intelligent transformation of traditional reinforcement methods, and the trend towards self-matching in intelligent reinforcement design. Key technologies, including intelligent perception and monitoring, data analysis and processing, and optimization algorithms for intelligent self-matching design, have broadened the understanding of intelligent self-matching reinforcement. However, a systematic review of the overall framework is lacking. Consequently, this paper organizes and elaborates on the intelligent development of slope stability calculations and evaluations, the intelligent transformation of traditional reinforcement methods, and the overall framework of intelligent self-matching. It proposes the concept of intelligent self-matching, offers a reference for design institutes to compare schemes, and promotes the advancement of slope reinforcement technology towards intelligent self-matching.

The instability and failure of hazardous rock masses, along with the resulting geological disasters, pose significant threats to infrastructure construction and operation. This study focuses on a rock slope along the G318 National Highway in the Xizang Autonomous Region as its research background, analyzing the potential risks of hazardous rock masses in the area and identifying the characteristics of the primary controlling structural planes. Using unmanned aerial vehicle (UAV) photogrammetry, slope imagery is acquired and a dense point cloud is generated to construct a digital surface model. UAV photogrammetry is employed to acquire slope imagery and generate a dense point cloud for constructing a digital surface model. A three-dimensional laser scanner is utilized to obtain high-precision point cloud data of hazardous rock mass and create a triangulated surface model. The geometric information of secondary structural planes within the rock mass is identified and interpreted using the coordinate data from the point cloud. A three-dimensional discontinuous deformation analysis (DDA) numerical model of the slope and hazardous rock masses is developed, optimizing modeling efficiency and computational feasibility. The stability of hazardous rock masses and the spatial kinematic disaster mechanisms post-failure are quantitatively analyzed by integrating the failure process with time-history curves of block displacement and kinetic energy. The results indicate that the hazardous rock mass I initially fails in a sliding mode when time≤1.0 s, subsequently evolving into a combined sliding and rotational mode. Tensile cracks develop between the rear edge and the slope, while shear failure occurs at the interface between the rock mass and the bedrock. The violent sliding of block II-4 in hazardous rock mass II triggers a rockfall disaster, with the maximum combined kinetic energy of impact reaching 259.186 MJ. Meanwhile, blocks II-1, II-2, and II-3 exhibit cascading failure effects due to dislocation and crack propagation. The instability of hazardous rock mass I directly triggers the failure of hazardous rock mass II, which subsequently influences the motion and evolution of mass I, leading to mutual interaction and merging of collapse blocks. This results in the formation of a large-scale block system, significantly increasing the overall volume and impact potential of the rockfall. Integrating UAV photogrammetry and three-dimensional laser scanning as non-contact measurement technologies notably enhances the modeling accuracy and efficiency of the three-dimensional DDA method. This research elucidates the dynamic interaction mechanisms involved in hazardous rock mass collapse and provides a theoretical foundation and technical reference for preventing and mitigating hazardous rock mass disasters.

The stratification characteristics of seabed soils significantly influence the reverse catenary properties of the installation line and the trajectory of the drag anchor. Theoretical analysis and derivation establish models for the reverse catenary shape and drag force of the installation line in layered clay. Degradation verification and comparative analysis demonstrate the validity and necessity of the established theoretical model. Based on the coupled Eulerian-Lagrangian method, the drag force theoretical model is integrated into the finite element model via a user subroutine, creating a large deformation finite element analysis method for the interaction among the installation line, drag anchor, and layered seabed. A sensitivity analysis of the subroutine parameters determines the optimal value of the key parameter ΔT/tc, comparing with existing numerical analysis and small-scale model test results. The results indicate that, compared to homogeneous clay, the stratification characteristics of soil lead to more complex variations in drag force, thereby affecting the anchor trajectory. Compared to the direct modeling approach for the installation line, the proposed method enhances computational efficiency by 56.64%.

Accurately revealing the evolution patterns of pressure and temperature in salt caverns is essential for analyzing the stability and safety of hydrogen storage facilities. A model was developed to describe the evolution of temperature and pressure in the cavern, based on the thermo-hydro-mechanical coupling effects during cyclic injection and production. Additionally, methods for calculating the temperature influence zone and thermal stress in the surrounding rock were proposed. The model’s validity and accuracy were verified using on-site temperature and pressure monitoring data from the Melville salt cavern storage facility in Canada, achieving over 90% consistency. The research results indicate that, under cyclic injection and production, the temperature in the salt cavern hydrogen storage facility exhibits a wave-like periodic variation over time, described by a piecewise bi-exponential function. In contrast, the pressure varies periodically in the form of an irregular sawtooth wave, represented by a piecewise combination of linear and bi-exponential functions. Both temperature and pressure initially experience synchronous increases (during injection) or decreases (during production), followed by a synchronous stabilization phase after injection and production cease. The duration of each phase is primarily influenced by the injection and production pressures, flow rate, and the convective heat transfer effects in the surrounding rock. Under daily injection and production modes, the pressure during the stabilization phase changes very slowly in the short term, evolving into a periodic trapezoidal wave pattern. During cyclic injection and production, the surrounding rock experiences thermal stress and additional displacement due to temperature changes in the cavern. The temperature fluctuations in the salt cavern primarily affect the surrounding rock within 5 m of the cavern wall under single injection and production conditions ranging from 8 MPa to 16 MPa. Due to hydrogen’s superior heat transfer and convective efficiency, the temperature influence zone in the surrounding rock during hydrogen injection and production is significantly larger than that of other energy storage gases.

Rock pillars are critical support structures that ensure safe mining operations in underground mines. Accurately predicting rock pillar stability is essential for ensuring safety in underground spaces. Consequently, we propose a novel robust random forest algorithm to predict rock pillar stability. First, we established a dataset comprising 317 hard rock pillars. We select six feature variables as input parameters through recursive feature elimination with cross-validation: pillar width, pillar height, the ratio of pillar width to height, uniaxial compressive strength, average pillar stress, and the ratio of average pillar stress to uniaxial compressive strength. Additionally, we employ chained equation multiple imputation and isolated random forest algorithms to address missing values and outliers. Second, to address decision redundancy and performance loss potentially caused by low-quality decision trees in the random forest algorithm, we introduce a decision tree purification mechanism and a precision weighting strategy. This enhances decision-making efficiency and prediction accuracy, leading to the development of a robust random forest model for predicting hard rock pillar stability. Finally, we evaluate the accuracy, advancement, and reliability of the models through performance evaluation, model comparison, model explanation, and engineering validation. The results indicate that the proposed algorithm achieves satisfactory predictive performance without requiring parameter optimization. The model’s predictive accuracy reaches 88.9%, outperforming other machine learning models, thereby providing effective guidance for evaluating the stability of hard rock pillars in underground mines.

To effectively address the impact of rail transit vibrations on the environment, we proposed a quasi-zero stiffness locally resonant metamaterial (QZS-LRM) vibration isolation structure composed of steel and thermoplastic polyurethane rubber. Finite element software was utilized to demonstrate the quasi-zero stiffness characteristics of the structure in both horizontal and vertical directions through preload method. We analyzed the mechanism of band gap generation, discussed the influence of preload on the band gap, and validated the accuracy of the band gap range using the transmission spectrum. Additionally, we compared the vibration isolation performance of the horizontal and vertical arrangements and verified the vibration isolation effect of QZS-LRM using measured high-speed rail vibration data. The results indicate that a larger preload leads to a lower band gap initiation frequency and an increased bandwidth. The transmission spectrum confirms the band gap range, and the vibration isolation effect of the horizontal arrangement is significantly superior to that of the vertical arrangement. Based on the measured acceleration data from the Shanghai-Kunming high-speed railway, frequency domain and time domain analyses reveal that the maximum acceleration amplitude attenuation exceeds 90% in both cases, confirming the effective vibration isolation performance of QZS-LRM.

Nonlinear elastic constitutive models are one of the most commonly used constitutive models in geotechnical engineering, extensively applied in mechanical performance analysis and numerical simulations. For nonlinear elastic constitutive problems, numerical algorithms are generally employed to solve them due to the iterative process involved in each incremental step. Recently, physics-informed neural networks (PINN) have emerged as a prominent method for solving partial differential equations, offering a novel approach to geotechnical engineering challenges. Currently, predictions of nonlinear constitutive problems using physics informed neural networks often depend on stress-strain field data derived from numerical methods. Although this data-driven and physics-driven integration can improve the accuracy of predictions, it does not break away from the framework of numerical solutions and also reduces the ability of neural networks to solve problems independently. To address this, a physics-driven incremental step PINN architecture is developed specifically for nonlinear elastic constitutive problems. This architecture generates a set of sub-networks for training corresponding to each incremental step and utilizes transfer learning to accelerate the training efficiency of neural networks in each incremental step. The study evaluates the performance of the proposed incremental physics informed neural network architecture by testing the Duncan-Chang model, a representative nonlinear elastic constitutive model, in solving two-dimensional plane strain problems. The effectiveness and accuracy of the proposed network architecture are validated by comparing the neural network predictions with computational results obtained from finite element software.

The stability analysis of bedding slopes in soil–rock composite strata under rainfall conditions is complex due to the differing hydro-mechanical properties of rock masses and soil. By developing Fish functions, the saturated–unsaturated seepage module in the FLAC3D software is improved, the calculation of matric suction in the unsaturated zone is refined, and dynamic adjustment of the seepage boundary is achieved. Based on numerical simulations, the influences of the permeability of the underlying rock mass, the dip angle of the soil-rock contact zone, and the rainfall intensity on the stability of bedding slopes in soil-rock composite strata are analyzed. Results indicate that low permeability of the underlying rock mass leads to rainwater accumulation at the soil-rock interface, increasing the susceptibility of the overlying soil to saturation and reducing the slope’s safety factor. A steeper dip angle at the soil-rock contact increases the saturation of the overlying soil. During rainfall, the potential sliding surface first migrates toward the slope surface and then gradually extends into the slope’s interior. With the same total rainfall, lower rainfall intensity promotes more uniform infiltration into the slope, further decreasing the safety factor and deepening the potential sliding surface. This improved method addresses FLAC3D’s limitations in simulating saturated-unsaturated seepage behavior and reveals the evolutionary patterns of slope stability under rainfall conditions, providing methodological support and a theoretical basis for slope reinforcement design.

Actively heated fiber-optic (AHFO) sensing tubes for measuring soil water content provide exceptional spatial resolution and continuous spatio-temporal measurements, thus gaining significant traction in vadose-zone hydrology. The layout method of AHFO sensing tubes often determines their coupling with the soil, which affects the accuracy of water content measurements. To date, a systematic evaluation of layout methods has been notably absent. This study focuses on a typical AHFO sensing tube, utilizing thermal response tests and rainfall infiltration tests to evaluate soil water content measurements under three vertical layout methods (direct insertion, backfilling, and penetration) and one horizontal layout (backfilling) method. Results indicate that the vertical direct insertion method can create interfacial voids between the sensing tube and the soil, facilitating preferential flow along the tube-soil interface. The horizontal backfilling method impedes water migration due to hydraulic obstruction caused by the tube. In contrast, the vertical backfilling and penetration methods effectively capture piston-flow infiltration phenomena during rainfall events and are regarded as the optimal layout methods for AHFO sensing tubes. It is recommended to select the appropriate layout method based on monitoring objectives and site conditions in practical applications.