This study focuses on flexible protection mesh fabricated from high-strength polyester fibers for addressing rockburst protection challenges in deep tunnels. Material mechanical parameters were determined through static tests and a modeling method for flexible mesh that can reflect the mechanical behaviors of strips and nodes was proposed based on Abaqus Explicit. Drop weight impact simulations were conducted and the model reliability was verified by comparison with existing tests. On this basis, a finite element model of the bolt-mesh system was established and multi-condition numerical simulations were conducted considering different impact positions, bolt spacings, plate sizes, and bolt patterns. This study reveals the dynamic response characteristics of the flexible protection mesh and clarifies the influences of various factors on the protective performance of the mesh. The results show that: (1) Numerical simulation can accurately simulate the mechanical behavior of the flexible mesh under drop weight impact, with an error of ≤ 5

In highway widening projects, the wet-dry cycling effect of weakly expansive soil fill under seasonal groundwater fluctuations exacerbates differential settlement. This study establishes a three-dimensional numerical model for a widened road with weakly expansive soil, based on a redeveloped numerical method and actual engineering projects. Through multi-scenario numerical simulations, the influence patterns and weighting factors of widening methods, road height, and water level on differential settlement were clarified. Three safety levels for differential settlement were defined using 6 cm and 12 cm as thresholds. A prediction model based on support vector machines was established to determine the combined threshold limits of key parameters under different differential settlement boundaries. The control effectiveness of sand replacement, water-blocking layers, and wicking geotextiles was comparatively evaluated: sand replacement reduces differential settlement by approximately 70% on average and is applicable to all scenarios; water-blocking layers reduce settlement by about 50% and are more suitable for bilateral widening or unilateral widening of low embankments; wicking geotextiles are unsuitable for controlling differential settlement in high-water-level areas. Selection principles for control methods under different conditions were proposed based on engineering requirements, and field tests validated the effectiveness of the proposed solutions.

When simulating unsaturated expansive soil, the total strain in the soil is decomposed into the strain induced by external loading and that caused by moisture expansion. Correspondingly, a modified strength-constitutive model accounting for soil degradation and machine-learning prediction model for the swelling coefficient are established. Four user subroutines are developed based on ABAQUS, embedding the strength model and facilitating interactions between the machine-learning model and computational program, during simulation. Simulations are conducted to analyze the deformation behaviors of weakly expansive soils under various water levels. The user-defined field subroutine is employed to acquire, store, and update parameters such as the stress and saturation. The user-defined data-exchange subroutine facilitates interactions between ABAQUS and the machine-learning models. The user-defined material and user-defined thermal expansion subroutines calculate the stress-strain and expansion strain, respectively. The program is validated using laboratory and field-test results, confirming the numerical-method's effectiveness. Furthermore, the long-term deformation characteristics of highway-widening projects on expansive-soil subgrades under extreme conditions are analyzed. Results indicate that, under fluctuating water levels, the expansive-soil subgrade deformation significantly influences the differential settlement, with the maximum settlement shifting from the joint area toward the shoulder. The proposed method demonstrates substantial application potential, offering valuable guidance for the rational design of road-widening projects in expansive-soil regions.

The stability of surrounding rock in underground compressed air energy storage (CAES) caverns is critical to the safe and stable operation of gas storage systems, and cavern displacement serves as a key indicator for evaluating rock mass stability. In this study, numerical simulations of excavation and gas injection were conducted for 1296 combinations involving cross‑sectional shape, cross‑sectional size, cavern spacing, gas pressure, burial depth, and rock category. The influences of these factors on the horizontal and vertical deformation behaviors of CAES caverns were systematically investigated. The results demonstrate that cavern displacement increases with increasing cross‑sectional size, cavern spacing, and gas pressure, whereas it decreases with increasing burial depth and improving mechanical properties of the surrounding rock. Owing to the multi‑cavern effect, twin caverns exhibit smaller displacements than single caverns. Using the six factors as input parameters, the conventional support vector regression (SVR) model was optimized via K-fold cross-validation and genetic algorithm to establish a displacement prediction model. Model performance was evaluated using the coefficient of determination (R²), mean absolute error (MAE), and root mean square error (RMSE). The GA‑KCV‑SVR model achieved superior performance compared with both the SVR and RF models.

Karst is a significant factor leading to hazards during engineering construction. In geologically complex plateau regions, the unclear mechanisms of karst development and the low accuracy of current assessment methods are particularly prominent issues. To enhance the prediction capabilities of karst development in plateau regions, this study establishes an evaluation system for the Developmental Characteristics of Subsurface Karst in Plateaus (DCSKP) based on attribute interval evaluation theory (AIET). Drawing on investigations of plateau engineering cases and karst development states, nine dominant indicators were selected as evaluation indicators by comprehensively considering the influences of stratigraphic lithology, geological structures, groundwater characteristics, surface karst geomorphology, and hydrochemical dissolution conditions on DCSKP. Furthermore, through laboratory dissolution experiments, the mechanism by which groundwater pH influences karst development was revealed, thereby establishing classification criteria. The evaluation results are highly consistent with the karst distribution observed during excavation, confirming the reliability of this method. The results indicate that when pH is utilized as an evaluation indicator, its classification thresholds can be defined as 4, 5, and 7. Normalizing evaluation indicators combined with the analytic hierarchy process (AHP)—extenics correlation analysis (ECA)—game theory (GT) integrated weighting method can enhance the accuracy of evaluation results. The AIET supports the reliability analysis of these results, providing valuable guidance for predicting and preventing risks associated with karst-related hazards in plateau tunnel engineering.

To investigate the energy relief effect of real-time drilling in preventing rockburst in high-stress rock, a series of high-stress real-time drilling uniaxial compression tests were conducted on red sandstone specimens using the SG4500 drilling rig. Results showed that the mechanical behavior (i.e. peak strength and rockburst intensity) of the rock was weakened under high-stress real-time drilling and exhibited a downward trend as the drilling diameter increased. The real-time drilling energy dissipation index (ERD) was proposed to characterize the energy relief during high-stress real-time drilling. The ERD exhibited a linear increase with the real-time drilling diameter. Furthermore, the elastic strain energy of post-drilling rock showed a linear relationship with the square of stress across different stress levels, which also applied to the peak elastic strain energy and the square of peak stress. This finding reveals the intrinsic link between the weakening effect of peak elastic strain energy and peak strength due to high-stress real-time drilling, confirming the consistency between energy relief and pressure relief effects. By establishing relationships among rockburst proneness, peak elastic strain energy, and peak strength, it was demonstrated that high-stress real-time drilling reduces rockburst proneness through energy dissipation. Specifically, both peak elastic strain energy and rockburst proneness decreased with larger drill bit diameters, consistent with reductions in peak strength, rockburst intensity, and fractal dimensions of high-stress real-time drilled rock. These results validate the energy relief mechanism of real-time drilling in mitigating rockburst risks.

The shear behavior and failure mechanisms of non-persistent joints are key to the stability of jointed rock masses, whose shear responses are jointly governed by geometric parameters such as joint aperture and joint persistence. In this study, direct shear tests were performed on specimens containing coplanar non-persistent joints, and the shear-failure process was simulated using the finite element method-cohesive zone model (FEM-CZM) method. The combined effects of joint aperture and joint persistence on shear behavior were investigated from both macroscopic and mesoscopic perspectives, and an improved Jennings shear strength criterion incorporating the weakening effect of joint aperture was derived. The tests revealed two typical post-peak failure patterns: a "sudden drop followed by arcuate recovery" and a "stepwise decline". Increases in both the joint aperture and joint persistence reduce the peak shear strength, with joint persistence exerting a more pronounced influence. Larger joint apertures increase the degrees of rock bridge fracture surface undulation and specimen surface spalling, whereas higher joint persistence flattens the fracture surface and mitigates surface spalling. Simulations indicate that stress initially concentrates at the rock bridge ends and extends towards the middle during shearing. The number of cracks increases sharply at the peak shear stress, with tensile cracks consistently dominating. Larger joint apertures intensify the stress concentration at the rock bridge ends, leading to earlier crack initiation, a more vigorous crack propagation trend, and more dispersed crack paths, whereas higher joint persistence narrows the stress concentration zone and accelerates crack coalescence across the rock bridge. Finally, based on the test and simulation results, an improved Jennings shear strength criterion is proposed by introducing a cohesion reduction coefficient eta(d) that decays exponentially with joint aperture. The validation results demonstrate that the predicted peak shear strengths agree well with the measured values and external data.

Min County experiences intense debris flow activity due to extreme weather and geological events. This study analyzes debris flow activity in Min County using GIS spatial analysis, time-series statistics, correlation analysis, periodic fitting, and field investigations across four event-based key periods (2002, 2012, 2013, and 2020). Long-term meteorological records (1951-2020) are introduced to support climatic trend analysis. Results indicate that stratigraphic lithology and fault tectonics control about 85-90% of the spatial distribution of debris flows, while extreme short-duration rainstorms trigger large-scale outbreaks and strong earthquakes further intensify activity. The high-occurrence cycle of debris flows (7-8 years) does not fully align with the annual wetness cycle (12 years). On a short time scale (years to decades), extreme earthquakes and rainstorms exert more significant impacts than normal precipitation patterns. This study preliminarily infers potential future peak periods of debris flows in Min County, with uncertainty from climate fluctuations and uncertain seismic events considered. The coupled mechanism of seismic weakening and rainfall triggering, together with lag-time characteristics, is revealed to support disaster prevention and mitigation.

The transportation infrastructure in high-altitude regions such as the Qinghai-Tibet Plateau in China is frequently affected by frost heave and thaw settlement diseases. The active regulation of moisture in wicking geotextiles is an effective way to control roadbed frost disease, but currently, no studies have investigated the control characteristics of wicking geotextiles based on the thermal-hydraulic-mechanical (THM) coupling mechanism. This study conducts one-dimensional temperature-controlled experiments on soil columns. Firstly, a large-scale soil column freeze-thaw cycle system is developed, which can restore the characteristics such as ultraviolet radiation, temperature and moisture, and groundwater. Using this experimental system, six sets of parallel freeze-thaw cycle tests on silt soil columns were conducted to analyze the temperature change mechanism, moisture migration characteristics, and settlement evolution process of 0, 1, and 3 geotextile layers under continuous water supply conditions. Subsequently, 105 sets of triaxial shear tests are conducted with saturation, freeze-thaw cycle number, and freezing temperature as independent variables. Based on the testing results, a cohesive degradation expression is constructed to describe the hydrothermal conditions. The findings provide material and methodological support for mitigating frost heave and thaw settlement damage in high-altitude regions.

The strain energy storage index (WET) is a crucial index for evaluating rockburst proneness. Interestingly, when conducting tests to obtain WET, variations exist in the shape of coal or rock specimens. However, whether shape factors affect WET has not been theoretically and experimentally verified. In this study, to investigate the independence of WET from specimen shape effects, its rationality was first theoretically derived based on the linear energy storage (LES) laws of rock, indicating that WET is influenced by the energy storage coefficient (ESC) of the rock. Two typical rock materials (granite and red sandstone) with different rockburst proneness were selected to verify the migration effect of cubic and cylindrical specimens on WET via uniaxial compression tests. The experimental results revealed that the mechanical behavior characteristics of rocks were affected by the shape of cylindrical and cubic specimens, whereas the WET and ESC were opposite. Furthermore, the practical WET values closely approximate the theoretical values of energy storage-dissipated ratio predicted by the LES law, converging to the peakstrength strain energy storage index (WPET). Based on the LES law, the influence of specimen shape on WET and WPET was further discussed, concluding that WET and WPET are independent of specimen shape effects. Furthermore, the WPET is more stable than WET and reflects the relative magnitude of energy storage and dissipation during the entire pre-peak of rock. Thus, the peak-strength strain energy storage index can be used as a substitute for WET in evaluating the rockburst proneness of rock. (c) 2026 Institute of Rock and Soil Mechanics, Chinese Academy of Sciences. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/bync-nd/4.0/).

Settlement prediction for high-speed railway embankments founded on natural clay is commonly based on macroscopic compressibility indices, which provide limited insight into the microstructural origin and stress dependence of deformation. This study investigated two Quaternary natural clays sampled near the Beijing–Shanghai High-Speed Railway in Kunshan under vertical stresses relevant to medium- to high-fill embankments. A medium-to-low-compressibility (MLC) clay and a medium-to-high-compressibility (MHC) clay were examined using one-dimensional compression, particle-size analysis, X-ray diffraction, and mercury intrusion porosimetry; quantitative environmental scanning electron microscopy was additionally conducted for the MLC clay. At 400 kPa, axial deformation reached 3.03 mm for the MHC clay, compared with 1.41 mm for the MLC clay. The wider particle-size distribution and higher quartz content of the MLC clay were associated with a more stable particle skeleton and a concentrated pore-throat distribution, whereas the MHC clay exhibited dispersed multiscale pore-throat reorganization. For the MLC clay, the total pore-area percentage decreased by 40.9% from 0 to 400 kPa. Cross-scale indices revealed strong coupling among macroscopic compression, pore-throat redistribution, and pore-area loss (R2≥0.955). A stress-normalized activation index further identified 100-200 kPa as the peak microstructural reorganization interval, well below the preconsolidation pressure of approximately 684 kPa. These findings indicate that concentrated microstructural activation can precede macroscopic yielding and provide a structure-sensitive basis for identifying critical deformation stages during staged embankment loading.

Clarifying the swelling and shrinking characteristics of expansive soils is crucial to addressing engineering problems in regions with such soils. This study collected deformation data of expansive soil under different hydraulic pathways during wetting-drying (W-D) cycles through laboratory experiments. The results revealed that both the W-D amplitude and vertical stress affect the volumetric change behavior of expansive soils during W-D cycles. The soil reached an elastic volumetric state after multiple W-D cycles, in which the swelling-shrinkage strain decreases with increasing vertical stress or decreasing W-D amplitude. Additionally, machine learning models were trained with different algorithms and data formats based on the time-series characteristics of soil deformation. The results demonstrate that using deformation data as sequential inputs to train sequence-based machine learning models significantly improves prediction accuracy. The gated recurrent unit model yielded optimal prediction accuracy (test set R-2 > 0.92), consistently outperforming traditional artificial neural network models. Furthermore, the study highlights the critical role of experimental design in model performance, revealing that the judicious selection of test conditions is more critical for enhancing model accuracy than merely increasing the number of tests. The predictive model maintained high accuracy (R-2 = 0.80) under the optimal testing scheme (42% experiment reduction). The findings provide a valuable reference for predicting the deformation of expansive soil.

Mud and water bursts within fault fracture zone frequently lead to casualties, equipment damage, and project delays, posing significant risks. A thorough scientific understanding of these mechanisms is essential for effective disaster prevention and control. To investigate the evolution mechanisms of mud and water burst in fault fracture zones, an experimental apparatus was designed to simulate the migration and loss of filling material particles under triaxial loading conditions. Experiments conducted with this apparatus explored the evolution process of mud and water bursts under varying initial dry densities. The results demonstrate that the evolution of mud and water bursts is a complex process, characterized by increased porosity and permeability, decreased strength, and fluctuating viscosity. The initial dry density plays a critical role in determining the failure mode of mud and water bursts. At low initial dry densities, the filling material is prone to seepage failure. In contrast, at high initial dry densities and elevated water pressures, the material is more likely to experience splitting failure. In comparison to seepage failure, the evolution process of splitting failure exhibits a significant delay, with a longer incubation period. However, it can rapidly form seepage channels in a short time, leading to more severe mud and water bursts. Finally, the study analyzed variations in porosity, permeability, and shear strength associated with different failure modes. Generalized models were established to describe the evolutionary characteristics of both seepage and splitting failure. These findings offer valuable insights for improving the safety and stability of tunnel engineering in environments prone to such risks.

Carbon dioxide (CO2) fracturing tubes have been applied as a novel blasting technique in rock blasting. However, the three-dimensional evolution of fracture networks induced by CO2 blasting remains poorly investigated. Therefore, this study conducted on-site blasting tests on 1 m3 rock specimens. Field data were used to validate numerical simulations, and phase-transition blasting processes were further simulated under varying expansion ratios and loading durations. The results indicated a fractal dimension of 1.578 for the fracture network, with rock fragments exhibiting greater uniformity than those generated by traditional explosive blasting. The internal fracture network comprised interconnected radial and circumferential fracture planes. A linear positive correlation was observed among the particle expansion ratio, the total fracture count, and the input energy. Moreover, the density of radial fracture planes and the fracture network increased with the expansion ratio. In contrast, the total number of fractures and blasting energy demonstrated a quadratic inverse relationship with loading duration. Shorter loading durations led to a dense distribution of fracture networks around the blasting hole and increased heterogeneity of rock fragments. As the loading duration increases, the fracture number curve exhibited a significant lag compared to the particle expansion curve. These findings advance the mechanistic understanding of CO2 fracturing tubes and optimize blasting efficiency.

To investigate how geotextile influences the rule of moisture transfer in clay, this study designed and conducted a moisture migration experiment using soil columns. Three sets of experiments were conducted under various conditions: without geotextile, with undrained geotextile, and with drained geotextile. The effect of drained geotextile on the change of moisture content was clarified by monitoring moisture content during 14 days of maintenance in constant temperature and humidity environment. The application of drained geotextile accelerated the decrease of moisture content in the soil samples, while the undrained geotextile significantly inhibited the moisture discharge from the soil samples. To further clarify the moisture regulation effect of drained geotextile, this study simulated the process of moisture migration under the action of drained geotextile by constructing a numerical simulation model, and carried out multifactorial simulation based on the response surface method after verifying the validity of its calculation. The results indicated that the parameters ksx and n of drained geotextile water characteristic curve and the geotextile horizontal permeability coefficient ksx had obvious effects and interaction. The optimal values for each parameter, which would maximize the reduction of moisture content, were determined through an optimization analysis using the response surface method.

Roadbed engineering in alpine tundra environment is prone to frost heave and thaw settlement, cracking of pavement, uneven settlement, and other challenges under the action of seasonal freeze-thaw cycle. Wicking geotextile has important application value in frost damage control of roadbeds, but solar radiation, especially ultraviolet radiation, is one of the main factors leading to premature failure of wicking geotextile. In this study, different kinds of ultraviolet-resistant wicking fibers were developed by blending modification technology, and the various types of fibers were compared with each other in terms of their physical and mechanical properties, so as to obtain the optimal modified wicking fibers with the content of 2 % UV-1164 + 0.3 % B900 addition. Subsequently, a 20-day accelerated aging test was conducted on modified wicking geotextiles. The inhibitory effect of the modification treatment on the wicking geotextile indicating photo-oxidative aging was characterized by scanning electron microscope, and the effect on the mechanical properties maintenance of the wicking geotextile was characterized by tensile strength and top-breaking strength tests. Finally, a soil column drainage test was designed and carried out, based on which the horizontal hydraulic conductivity rate and 120-h drainage volume of wicking geotextiles before and after the modified treatment were predicted under the aging cycle of 40 d. The test and prediction dates showed that the hydraulic conductivity was deteriorated with the aging time, but the modification treatment could obviously inhibit the deterioration degree. Compared with the control group, the hydraulic conductivity of the modified wicking geotextile increased by about 0.35E-5 g/s, and the drainage capacity increased by 0.76 % at 200 h.

The cement-fly ash composite expansive stable grout was prepared to deal with the problems of poor stability and volume shrinkage of ordinary cement grout,and the effects of fly ash ratio and water-binder ratio on the properties of the grout and its consolidation were analyzed.In addition,the mineral composition and microstructural characteristics of grout consolidation with different mixing ratios were investigated.The experimental results indicate that fly ash and the increase of water-binder ratio reduce the strength of the grout consolidation,and increase the fluidity,bleeding rate,and setting time of the composite grout.However,the magnitude of the fly ash-induced strength reduction decreases with time.And the effect of fly ash on the setting time and compressive strength becomes more significant with the water-binder ratio.The later expansion performance of grout consolidation (after 7-42 d) is improved by fly ash.But the expansibility of consolidation with fly ash decreases at the early curing stage,and the reduction amplitude of expansion rate is smaller and the reduction age is shorter with the water-binder ratio increase.Fly ash improves the corrosion resistance performance of grout consolidation,and the corrosion resistance coefficient rises first and then falls with the fly ash ratio.And for 0.6:1 water-binder ratio,the corrosion resistance coefficient of the samples mixed with fly ash are greater than 100%.XRD and SEM show that fly ash inhibited the formation of ettringite in the early stage,which is unfavorable to the expansion of the slurry,and with the increase of age,this effect gradually weakened.

Noise pollution has become a significant environmental issue that negatively impacts human health and quality of life. Consequently, the development of sound-absorbing materials for effective noise control has garnered considerable attention. In this study, grain husk/polyurethane (GH/PU) composites were synthesized using a one-step chemical foaming method. Further, the effect of GH addition on their acoustic properties was investigated from a microscopic perspective. An orthogonal test method was then employed to determine the optimal composition of GH/PU (evaluated by the average sound absorption coefficient in 50-6300 Hz), which reached a maximum average value of 0.735. Simultaneously, the mechanical properties and damping properties of GH/PU were characterized: The maximum compression strength and tensile strength are 2.31 kPa and 232 kPa, and the damping loss factor reached a maximum of 0.712 at 10

Unsaturated seepage is one of the fundamental scientific problems in soil mechanics and a key focus of research in the field of geotechnical engineering. This study investigates the application of the wicking geotextiles as subgrade drainage materials in unsaturated soil moisture control through single parameter soil–water characteristic curves and permeability coefficient functions. Starting from the perspective of obtaining a secondary boundary with time variables based on mathematical construction, the control equation for unsaturated soil moisture migration under the action of the wicking geotextiles was equivalently decomposed, and analytical calculations were carried out using the separation of variables method. The analytical expressions for dimensionless permeability coefficient, seepage velocity rate, and volumetric moisture content were obtained. This study conducted drainage tests on silty clay columns with the application of the wicking geotextiles, obtaining the initial basic parameters and boundary conditions for analytical calculation of volumetric moisture content. The effectiveness of the analytical calculation was verified by monitoring the time history change curve of soil column moisture content through the test. The analysis expression can obtain the spatiotemporal distribution law of the moisture content in the soil column. The analysis results showed that the moisture content at the bottom of the soil column decreased from 20.75