To investigate the effect of fracture surface roughness on solute transport in a rough fracture and the effect on the hydrodynamic dispersion coefficient D_L and transport velocity V_t, roughness and hydraulic aperture of various fractures under constant head were calculated using fractal theory. The study discussed the influence of roughness on solute transport in rough fractures, as well as the seepage flow and solute velocity with different fractal dimensions. Breakthrough curves were generated by integrating the Navier-Stokes equation and the advection-diffusion equation (ADE). The breakthrough curves from direct simulation were coupled using the classical ADE approach. Subsequently, D_L and V_t were determined. The study explored the control exerted by D_L and V_t on solutes and their correlation with roughness. A prediction model based on fractal theory for solute transport in rough fractures was established and compared with direct simulation and geometric feature-based models. Results indicate that fractal dimension D and amplitude parameter K_v effectively characterize surface roughness, with a strong correlation between D_L, V_t, and fractal parameter DK_v. The established model demonstrates high applicability and accuracy in simulating solute transport in rough fractures.

 During the construction and operation of storage reservoirs, the complex stress path plays a crucial role in controlling the damage to the surrounding rock. However, the current study of surrounding rocks lacks a comprehensive consideration of stress paths, especially in terms of the principal stress axis rotation. In this research, a test on rock principal stress axis rotation was conducted using the rock torsion shear apparatus, and the stress field at the fracture tip under stress rotation was analyzed employing fracture mechanics theory. The findings suggest that stress rotation increases the tensile stress at the fracture tip, accelerates fracture propagation, and leads to a notable decrease in rock strength. A methodology for characterizing damage evolution considering stress rotation is proposed based on these findings. Once the maximum differential stress exceeds the first cracking stress, the rotation angles in each direction of the principal stress axis are summed to obtain the cumulative effective rotation angle. This angle is then used to delineate the excavation damage zones (EDZs) based on its variation with depth. The spalling zone is identified using the maximum depth of the damage zone and the range of differential stress that exceeds the second cracking stress. The method integrates the amplitude and rotation angle of the principal stresses to offer a more comprehensive response to the surrounding rock damage evolution mechanism. The validity of this approach is confirmed through a comparison between the numerical model of the Mine-by tunnel and the monitoring data. This study provides novel insights into the damage mechanism of surrounding rock and the prediction of the surrounding rock damage range.

This study aimed to enhance the efficiency of microbial-induced carbonate precipitation (MICP) for reinforcing sandy soil by inspiring natural processes involving microbial-induced carbon cycling and carbonation. The experiment focused on enhancing MICP curing of sandy soil using carbonic anhydrase (CA), which significantly increases the reaction rate of CO₂ hydration (10⁸ times faster) and facilitates the rapid hydration of CO₂ (produced by urease (UA) decomposition of urea) to form a substantial amount of carbonate. The effect of carbonic anhydrase on MICP-reinforced sandy soil and its underlying mechanism were systematically examined through a combination of macroscopic physical and mechanical tests and microfabrication tests. The results showed that: (1) CA significantly increases the production of cement during the microbial consolidation of sandy soils, and the optimum dose of carbonic anhydrase producing bacteria is reached at about 4%, which increases the production of cement by 105.3%, compared with conventional MICP. (2) The incorporation of CA improves the compressive strength and resistance of the cured body. In the range 0.25−4.00%, the unconfined compressive strength of the solidified soil sample increases with the increase of the CA bacteria content. The strength of the cured soil sample reaches 1.915 MPa when the content is 4%, which is 8.54 times the strength of the conventional MICP cured sample. (3) CA does not change the product of the MICP process, it is still calcite, but after adding CA, the grain size of the calcite is larger, the shape of the hexahedron is more standardised, and the mechanical properties are improved. (4) In the process of MICP, urease and CA co-precipitate calcium carbonate-cured sandy soil. CA can significantly accelerate the rate of urea-generated CO₂ hydrate and form HCO₃^-and CO₃^2-, providing more favourable conditions for mineralisation.

Geogrid, commonly used for reinforcement in rockfill dams, significantly enhances seismic performance when appropriate grid dimensions are selected based on particle size distribution. Investigating the variations in optimal grid dimensions influenced by particle size distribution is of great engineering importance. By employing the continuous grading equation, 15 sets of graded soils were developed by varying the maximum particle size d_max and grading area S. Creating 60 reinforced specimens by using four different grid sizes L_a to reinforce each soil. Subsequently, large-scale direct shear tests were performed on each specimen to quantitatively analyze the correlation between grading area and geogrid dimensions, aiming to optimize the seismic performance of reinforced coarse-grained soil. The experimental results show that there is an optimal grading area, S_opt, that maximizes seismic performance when d_max and L_a are fixed. When the grid size remains constant S_opt increases logarithmically as d_max increases. Conversely, when d_max is constant, S_opt decreases logarithmically as L_a increases. A quantitative model is developed to d_max describe the combined effects of d_max and L_a on S_opt. This model is integrated with engineering practices to propose an empirical formula based on indoor test results for predicting the optimal grid dimensions for the original grading of coarse-grained soil on-site.

The cementation formed by free iron oxide and its special structural connections between particles are closely related to the mechanical properties of laterite. To investigate the effect of free iron oxide on the mechanical properties of laterite in situ, selective dissolution of free iron oxide in laterite was carried out using a Dithionite-Citrate-Bicarbonate solution. The shear strength indexes of laterite at various depths under different iron removal conditions were determined through borehole shear testing (BST). The results indicated a significant correlation between the content of free iron oxide and the duration of DCB solution immersion, with a rapid removal rate in the initial stages followed by a slower rate in the later stages. The stress-strain curve of laterite exhibits strain hardening and deformation in BST testing. At the same depth, the shear strength of laterite decreases as soaking time increases, with a reduction of up to approximately 79.0% within the initial four days of testing. For the same soaking time and depth, the shear strength of laterite increases with increasing normal stress. Similarly, at the same soaking time and normal stress, the shear strength of laterite increases with the increase of depth. As soaking time increases, free iron oxide in the forms of “envelope”, “bridge” or “single particle” is progressively eliminated, leading to damage in the microstructure of laterite. The original dense structure develops pores, cracks, and becomes loose, resulting in a macro-level reduction in the mechanical strength of laterite.

Taking red sandstone as the research object, the intact and flawed red sandstone specimens coated with liner were made using a cement-based thin spray-on liner. The study examined how the thin spray-on liner affected the strength, deformation, and energy evolution of intact and flawed red sandstone under uniaxial compression. Furthermore, the study analyzed how the thin spray-on liner influenced the crack propagation characteristics of sandstone with different inclination angles through particle flow PFC3D software. The results indicate that red sandstone coated with the thin spray-on liner exhibited higher peak strength and strain compared to uncoated specimens. Moreover, the improvement coefficient for flawed sandstone exceeded that of intact specimens. In the post-peak stage, the internal rock of specimens with the thin spray-on liner was damaged, resulting in the formation of tensile cracks on the liner’s surface, although the specimens did not fully collapse. The total energy, elastic energy, and dissipation energy of specimens with a thin spray-on liner are greater than those of uncoated specimens. Moreover, a greater amount of input total energy is converted into dissipation energy post-coating. The PFC3D simulation results indicate that applying a thin spray-on liner can increase the initiation stress and peak strength of crack specimens at different inclination angles. The influence of a thin spray-on liner on the failure modes of specimens with varying crack angles. Specifically, at a 15º inclination angle, the thin spray-on liner hinders the propagation of tensile cracks in the post-peak stage. Conversely, at a 75º inclination angle, the crack propagation behavior of specimens, whether coated or uncoated with a thin spray-on liner, is similar. These research findings can provide a reference for the application thin spray-on liners in engineering applications.

Natural soil layers often exhibit overconsolidation due to their deposition history, which significantly affects soil mechanical properties. However, traditional analytical methods for determining critical tunnel face pressure are ineffective in considering the overconsolidation effect. This study introduces a nonlinear Hvorslev surface as the strength criterion for overconsolidated soil. The equivalent Mohr-Coulomb strength parameters are derived using the tangent technique and then incorporated into the modified three-dimensional collapse analysis. A new model is established to predict the critical face pressure of tunnel faces in clay layers with varying overconsolidation ratios (OCR). The model’s validity is confirmed by comparing it with the existing model in its simplified form. The critical tunnel face pressure (σ_c ) in overconsolidated soil is influenced by the overconsolidation ratio (OCR), tunnel diameter (D), the ratio of the swelling line slope to the compression line slope (κ*/λ* ), pore water pressure coefficient (r_u), soil lateral pressure coefficient (K₀), tunnel depth-to-diameter ratio (C/D), and the stress ratio at critical state (M). The findings show that with increasing OCR, the collapse zone at the tunnel face shrinks, leading to a decrease in the critical tunnel face pressure (σ_c). When OCR is constant, σ_c  positively correlates with D, κ*/λ*, and r_u, while negatively correlating with K₀, C/D, and M. The impact of κ*/λ*  on σ_c  is significant at high OCR values, and C/D and K₀ have a high sensitivity at low OCR values. Therefore, to enhance the design of tunnel face pressure in overconsolidated soil, engineers should consider factors like stress history, OCR, tunnel dimensions, and depth.

Bentonite is commonly utilized as a waterproofing and buffering material due to its high expansibility and very low permeability. The cation exchange capacity is a crucial parameter that influences the microstructure of montmorillonite, thereby modifying its expansibility, hydraulic properties, and diffusion characteristics. Various montmorillonite samples with reduced cation exchange capacity were produced by heating lithium-modified bentonite at varying temperatures. By employing nuclear magnetic resonance and X-ray diffraction techniques, we acquired information on the distribution of pore water and interlayer spacing in montmorillonite with reduced cation exchange capacity under varying water content. Furthermore, we investigated the effect of cation exchange capacity on hydration in montmorillonite interlayers. The research demonstrates that a decrease in cation exchange capacity results in a reduction in the number of expandable layers, consequently lowering the liquid limit of bentonite. An preliminary approach for determining the proportion of expandable layers is suggested using the T₂ distribution curve derived from nuclear magnetic resonance. The results from this method closely align with the proportion of reduced exchangeable cations.

The presence of fractures significantly influences the physical and mechanical properties of rock masses. However, automated extraction of fractures from images of rock mass exposures frequently encounters challenges such as incomplete results, low signal-to-noise ratio, reliance on empirical parameters, and poor robustness. In response to these issues, a fully automated optimization procedure for the extraction of fractures is proposed. Firstly, the introduction of a generalized gamma correction is employed to preliminarily enhance the contrast between fractures and rock wall surfaces. Subsequently, by considering the mutual influence among pixels along fracture paths, a grayscale transmission algorithm is devised to improve the continuity of fractures. Finally, an improved Frangi filter is utilized for fracture extraction while effectively suppressing the response of noise pixels. The results indicate that the proposed procedure cleverly integrates two major characteristics of fractures: low grayscale and high linearity, and the coordination between the stages of image enhancement and fracture extraction significantly ameliorating the issue of uneven fracture contrast. Furthermore, while ensuring complete fracture extraction, it efficiently prevents the generation of noise and pseudo-fractures. The procedure demonstrates high robustness across various images of rock mass exposures. Comparative analysis with commonly used fracture identification algorithms highlights the advantages of the proposed procedure.

In the coal-rock system, the interlayer weak zone between coal and rock layers is the primary area of fracture distribution. These fractures penetrate the coal and rock layers, seriously impacting the mechanical properties and engineering stability of the coal-rock system. To investigate the impact of penetrating fractures on the mechanical properties of the coal-rock system, axial loading tests were conducted on prefabricated coal-rock composite bodies with five different fracture lengths and angles. The findings indicate that: 1) As the fracture length increases, the compressive strength, elastic modulus, peak energy, and impact energy index decrease linearly. Regarding the fracture angle, the compressive strength, elastic modulus, peak energy, and impact energy index initially decrease and then increase. 2) The destructive acoustic emission tests of the samples exhibit three stages: a quiet period, an active period, and an intense period, respectively. With increasing fracture length, the cumulative energy of acoustic emission initially increases and then decreases. Similarly, with increasing fracture angle, both peak energy and cumulative energy of acoustic emission first increase and then decrease. 3) The length and angle of fracture have a certain influence on the wing crack, secondary inclined crack, secondary coplanar crack, oblique crack, secondary derivative crack, wing crack derivative crack, far field crack and spalling phenomenon. 4) As fracture length increases, the cohesion and internal friction gradually decrease, while an increase in fracture angle leads to a decrease followed by an increase in cohesion and internal friction. 5) The Drucker-Prager strength criterion considering fracture length and angle was developed, and rationality verification indicated a sample error within a reasonable range of 1.367% to 5.055%. 6) Based on the dissipative structure theory, the study analyzed the mechanism of instability failure in the coal-rock combined body. The failure process of the combined body involved four main stages: quasi-steady state, metastable state, instability, and establishment of a new steady state. An energy migration model for the fractured coal-rock combined body was developed, and the energy migration pattern during the instability and failure of the fractured coal-rock combined body was analyzed. The ends of the fracture were identified as the primary areas of energy accumulation. Destruction of the coal component’s fracture end led to the migration of energy towards the fracture end of the rock component, resulting in the release of energy through rock component destruction or deformation. These research findings offer valuable insights for investigating the mechanical characteristics of deep coal and rock, as well as understanding the mechanisms behind dynamic coal and rock disasters.

This study aims to investigate the effects of wet-dry cycles caused by rainfall-evaporation and acid rain erosion on the stability of argillaceous sandstone slopes. It examines the degradation patterns of mechanical parameters and the evolution of damage and failure in argillaceous sandstone subjected to various acidic wet-dry cycles using uniaxial and triaxial compression tests and acoustic emission monitoring tests. The results indicate a positive correlation between the degradations degrees of uniaxial compressive strength (σ ), elastic modulus (E ), cohesion (c ), and internal friction angle (φ) of argillaceous sandstone and the number of wet-dry cycles. Conversely, the degradation rate shows a negative correlation with the cycles. Confining pressure retards the degradation process, while acidic environments intensify the degradation of rock samples with s being highly sensitive under acidic wet-dry cycles. Mechanical parameters exhibit a significant logarithmic relationship with the number of wet-dry cycles across different pH conditions. The acoustic emission ringing counts and energy evolution characteristics can be categorized into three phases: an initial active phase, a stable growth phase, and a peak rapid increase phase. Distinct precursors to abrupt failure are evident during the stable growth phase. The RA-AF tensile crack signals consistently decrease due to the strengthening effects of acidic wet-dry cycles. Additionally, the characteristics of acoustic emission localization events shift from a central axial cluster to an oblique random distribution, indicating a transition in damage from tensile to shear failure. The composite accuracy for identifying the damage state of argillaceous sandstone using an acoustic emission data-driven model achieved 93.33%. The ringing count and maximum energy features contributed 81.63% to this accuracy, highlighting the model’s ability to accurately capture the intrinsic correlation between damage state levels and acoustic emission data.

To reveal the damage evolution and fracture mechanism of rock-backfill composite structure in mine stope under frequent stress disturbance, a series of multi-stage increasing-amplitude fatigue tests and post-test CT scanning were carried out on rock-backfill combination with four different cement-tailings ratios. The results indicate that: 1) Deformation, stiffness degradation, damage propagation, and failure pattern of the rock-backfill combination are influenced by the cement-tailings ratio. Volume expansion increases, while the secant modulus initially rises and then decreases as the cement-tailings ratio decreases from 1:4 to 1:12. 2) An irreversible axial strain-based cumulative damage evolution model was proposed, which aligns well with the experimental data. For rock-backfill combinations with cement-tailings ratios of 1:4 and 1:8, the cumulative damage exhibits a two-stage increasing pattern, characterized by an initial steady rise followed by a sudden increase. Conversely, for rock-backfill combinations with cement-tailings ratios of 1:10 and 1:12, an inverted S-shaped damage accumulation pattern is observed, featuring a clear three-stage progression of initial, steady-state, and accelerated increase. 3) Decreasing the cement-tailings ratio transforms the rock-backfill combination samples from mixed tensile-shear failure to tensile failure. Post-test CT images depict the mesoscopic fracture evolution pattern of the rock-backfill combination, which comprises shear fractures in the backfill, tensile fractures along the rock-backfill interface, and tensile-shear fractures in the rock. The study suggests that implementing “flexible backfilling” can help mitigate disasters like rock spalling and collapse. These results offer a theoretical foundation for optimizing mine filling ratios and ensuring the safe extraction of deep mineral resources.

The study aims to investigate the impact of stepwise depressurization on the production characteristics of natural gas hydrate reservoirs to enhance the efficiency and controllability of hydrate production. A self-developed large-scale two-dimensional simulation test system was utilized to conduct stepwise depressurization experiments on a single vertical well of natural gas hydrate at three varying rates. The research focused on analyzing the effects of different depressurization rates on pressure response, temperature response, gas production, instantaneous gas production rate, and average gas production rate at the reservoir’s planar scale. The results indicate that abnormal peak phenomena in pressure change rate are closely associated with the back-pressure valve. The duration ratio is approximately inversely proportional to the depressurization rate. With the same depressurization magnitude, a lower depressurization rate results in a longer duration, enhancing external heat transfer and promoting greater hydrate decomposition during depressurization. This leads to a higher total gas production ratio. A decrease in depressurization rate delays the peak gas production rate in the second stage and shifts the time for maximum hydrate decomposition rate.

The joints in deep rock masses often contain weak filling materials to varying degrees, which leads to more complex mechanical properties of the rock mass. A shear test on the anchored and filled jointed rock mass is carried out under the constant normal stiffness (CNS) boundary condition, considering the combination mode of high initial normal stress and different joint roughness coefficient (JRC) - filling degree Δ. The microstructure evolution characteristics of the filled joint part are analyzed by combining the microscopic scanning electron microscope (SEM), and the calculation method related to the peak dilatancy angle under the CNS boundary condition is derived. The research results show that when Δ＜0.5, the shear stress strength of the specimen presents stress hardening; when 1.0＜Δ ≤1.5, the shear stress strength evolves from basically constant to stress softening. When Δ is less than critical filling degree Δ_cr , JRC becomes the main influencing factor of the peak shear strength. Δ controls the normal deformation of the joint. With the increase of Δ , three evolution laws of shear dilation, first shear dilation and then shear contraction, and shear contraction emerge, and JRC affects the degree of shear dilation - shear contraction change of the specimen. The failure mode of the filled joint part mainly undergoes three stages with the increase of Δ : flattening of rough points, friction of filling materials, and grinding of filling materials. From a microscopic perspective, it evolves from a loose and porous structure to a granular debris-like structure. Affected by the mutual evolution mechanism of the extrusion crushing zone and the extrusion stress concentration zone, the shear deformation mode of the anchor gradually evolves from the “approximate” tensile-shear deformation at Δ = 0 to the tensile-bending deformation mode at Δ = 1.5. On this basis, a calculation formula for the peak dilatancy angle of the anchored and filled jointed rock mass under the CNS boundary condition is proposed, and the test verification and the sensitivity analysis of the influencing parameters of the boundary condition are carried out.

Nodular diaphragm wall (NDW) is a novel foundation type with favorable engineering characteristics. In contrast to traditional diaphragm walls, the vertical bearing capacity of NDW is significantly enhanced by the existence of nodular sections. Currently, the application and research of NDW are limited, and further clarification is needed regarding its deformation properties and failure modes. This study employs particle image velocimetry (PIV) technology to analyze the displacement and failure mechanisms of the foundation under vertical uplift. The findings indicate that positioning end and middle nodular sections extend the influence range to both deep and shallow soil layers, while multiple nodular sections facilitate in mobilizing broader spectrum of soil. The failure pattens of NDW involve interconnected sliding planes, including vertical sliding planes, inverted pyramid-shaped, or tangent curves, and vase-shaped curves (referred to as curve sliding planes). Overall, compared to pile foundations, the failure surfaces of the retaining wall exhibit complexity, influenced by the number and arrangement of sections, with certain sliding plane orientations correlated with the soil’s internal friction angle.

Theoretical analysis of unfrozen water content in unsaturated soil below freezing temperature is conducted, presenting a simple prediction method and its mathematical model. By considering the chemical and mechanical balance of gas-liquid phases in unsaturated soil pores, along with the soil-water characteristic curve, the soil pore volume distribution density function is derived using parameters from the Van Genuchten soil-water characteristic curve model. The relationship between the maximum pore size filled with liquid water at initial effective saturation and initial crystal pore size at a specific freezing temperature is examined to analyze ice-water phase transition characteristics in soil pores and critical effective saturation. Freezing occurs only if initial effective saturation surpasses critical crystallization saturation. A formula for predicting unfrozen water saturation in unsaturated soil below freezing temperature is provided and validated against existing experimental data.

Road infrastructure construction in developing countries such as Vietnam requires an enormous amount of natural sand. The scarcity of river sand is becoming increasingly severe, with predictions indicating a sustained drop in its supply. Hence, it is essential for the construction industry to implement a sustainable strategy by combining waste materials with abundant resources in order to effectively address this challenging situation. The objective of this study is to investigate the mechanical properties and evaluate the potential application of mixtures comprising rock quarry dust and sea sand for the roadbed layers of expressways. The researchers conducted a series of experiments, including the moisture content, specific gravity, angle of repose of material, and triaxial tests to study the composition and mechanical behaviors of mixtures at different ratios. Extensive parametric investigations in conjunction with the calibration in Plaxis’ soil-test module obtain the Young’s modulus E₅₀ and confining pressure curves. Based on the assessment of materials utilized in roadbed layer of highway, as determined by the California bearing ratio (CBR) coefficient, it demonstrates that combining sea sand and quarry dust can generate the mixtures possessing appropriate properties for application in the construction of the roadbed of highway.

Conventional methods for liquefaction discrimination are often semi-empirical, prone to human factors, with low success rates and balance. Moreover, current machine learning approaches lack ample sample support and have specific limitations. Through the integration of liquefaction datasets, 11 features were chosen: corrected standard penetration test blow count, fine content, soil layer depth, groundwater table depth, total overburden stress, effective overburden stress, threshold acceleration, cyclic shear stress ratio, shear wave velocity, earthquake magnitude, and peak ground acceleration. A convolutional neural network (CNN) model was established. The Borderline SMOTE technique was introduced to address the issue of imbalanced datasets. The CNN model was compared against random forest, logistic regression, support vector machine, extreme gradient boosting models, and methods specified in Chinese codes. Furthermore, the SHapley Additive exPlanations (SHAP) algorithm was utilized to examine the influence trends of input features on the prediction outcomes. The results demonstrated that the CNN model attained an accuracy of 92.58%, outperforming all metrics of the four machine learning models and the method specified in Chinese codes. Examination of the SHAP results unveiled that soil layers with corrected standard penetration blow numbers below 15 exhibited a higher liquefaction probability, whereas layers with cyclic stress ratios under 0.25 were less prone to liquefaction. The influence patterns of each factor align with current understanding, indicating the prediction model’s credibility and reliability.

The saturated loess layer is susceptible to liquefaction failure, as evidenced by the liquefaction loess landslide in Zhongchuan triggered by the Jishishan M6.2 earthquake, and the Heifangtai loess landslides serve as typical examples. Nonetheless, the infiltration mechanism in loess remains elusive. A field irrigation test was carried out at the rear boundary of a representative landslide in Heifangtai, with the water infiltration process monitored using the 3D electrical resistivity tomography method. The cumulative rate of resistivity change was employed to depict the overall infiltration process, while the disparity in resistivity change rates between adjacent measurement intervals was utilized to identify the primary seepage pathways. The infiltration mechanism in loess was examined under varying recharge intensities. The main conclusions are as follows: (1) The time-series 3D electrical resistivity tomography method can effectively detect the infiltration process in loess. (2) There co-exists matrix flow and preferential flow in the test, the matrix flow is the main infiltration mode during the test. The preferential flow shows the gradual seepage around the preferential channel extending to a depth of 4 m, and the seepage area is affected by the distribution of preferential channel. (3) The infiltration mode in the fissured loess is affected by the intensity of water recharge. With the flood irrigation or rainfall water ponding, the water in the fissures can directly penetrate into the deep soil forming a preferential flow. While in case of rainfall without water ponding, there is no obvious preferential flow observed, and the water infiltrate only with matrix flow. The results can provide reference for the study of field infiltration test and infiltration mechanism in loess.

Landslides frequently occur in heavily vegetated areas of southeast Fujian Province due to typhoon rainstorms. Investigating the failure mechanisms and evolution patterns of landslides influenced by vegetation, rainfall, and strong winds is crucial for disaster mechanism, monitoring, and early warning of typhoon-induced landslides in densely vegetated regions. This study focuses on the Yangxie landslide in Yongtai County, Fujian Province, investigating response patterns and analysis methods for vegetated slope stability under wind-driven rain conditions. Pulling tests on moso bamboo and single-ring infiltration tests were conducted, integrating the Green-Ampt model and infinite side slope model. Detailed main results include: 1) Bamboo’s maximum wind resistance ranges from 18 m/s to 30 m/s, corresponding to wind forces of 8 to 11. 2) Soil infiltration capacity in the windward area increases with wind speed, remaining constant at 0–12 m/s but rising rapidly beyond 12 m/s. 3) The wetting front’s migration speed in the root-soil zone accelerates with increasing wind speed and rainfall. Typhoons disturb soil by swaying vegetation to create preferential flow, mainly accelerating the wetting front’s migration speed. Wind speed significantly impacts soil infiltration capacity under wind, rain, and vegetation interactions. 4) During typhoon rainstorms, wind loads enhance rainfall infiltration in the root-soil zone through vegetation, thereby speeding up the wetting front’s migration. This process is critical for typhoon-induced landslide occurrence and development.

The artificial freezing method is commonly used in tunneling beneath overlying structures due to the significant development and utilization of underground space. However, there is a growing demand for controlling frost heave deformation in overlying structures and the interaction laws of these structures during freezing and undercutting remain unclear. Hence, a multi-physics coupling deformation calculation method is proposed. This study focuses on the shield tunneling project of Shanghai Metro Line 18 at Guoquan Road Station, which intersects with the existing upper operating station of Line 10. It investigates the construction approach for new tunnels during freezing, using the gray clay of layer ⑤1 in Shanghai as the research target, particularly examining the disruptive effects on the primary structures of the upper operating station. Considering water migration, we derived the frost heave deformation formula and developed an improved thermo-hydro-mechanical coupling theory model by using pore ratio, freezing temperature, and average water pressure as coupling variables. Through frost heave tests on cohesive soil, we obtained the stress-strain relationship of frost heave specimens to describe the changes in pore structure. Subsequently, a thermo-hydro-mechanical three-field coupling numerical calculation was conducted using the weak form module (PDE) of COMSOL Multiphysics software. The simulation results closely matched the monitoring data and were below the predetermined control value, validating the accuracy of the enhanced coupling theory. These findings offer a multi-physics coupling approach for calculating deformations in similar frozen underpass tunnels, serving as a valuable reference for freezing method design and construction parameters. Additionally, we propose safety control indicators for reinforcement construction based on this scientific groundwork.

The existing underground structure blocks groundwater seepage (i.e., water-blocking (WB) effect) and restricts surrounding soil movement (i.e., soil-blocking (SB) effect). This leads to differences in the dewatering-induced behaviors of groundwater and strata compared to scenarios without nearby structures. In this study, a typical metro station was chosen as the nearby underground structure that impedes groundwater and soil flow. Three-dimensional hydro-mechanical numerical models were developed based on an actual foundation pit pumping test to analyze the dewatering-induced responses of groundwater and strata under different WB and SB effects. Factors such as the relative location of the metro station to the excavation, the buried depth of the station structure, and the dewatering depth in the model were considered. The results indicate that the presence of a metro station near the excavation site can either aggravate or restricte dewatering-induced ground settlement, depending on the strength of the SB and WB effects. The distance D between the excavation and the metro station determines the relatively strength of the SB and WB effects, thereby influencing whether the ground settlement is aggravated or restricted. On the other hand, the buried depth H of the station only singularly affects the intensity of the WB or SB effect and could not determine which barrier effect plays the dominant role. In practical engineering applications, it is essential to consider both WB and SB effects based on the proximity and buried depth of the adjacent station structure to effectively assess the dewatering-induced behaviors of groundwater and strata.

The assessment of model parameters is crucial in developing constitutive models. However, the results of parameter assessment for these models are inevitably subject to errors. Hence, a Bayesian framework utilizing structural reliability, subset simulation, and adaptive conditional sampling methods is employed to assess the uncertainty of constitutive model parameters through test data inversion. Using the joint shear constitutive model for shear stress-shear strain characterization of rock-soil mass and the hypoplastic clay constitutive model for nonlinear soil stress-strain increment description as case studies, this study investigates the uncertainties in model parameters, shear stress-strain curves, and pore ratio-pressure curves. Furthermore, it analyzes the sensitivities of model parameters to test outcomes. The research demonstrates that this approach evaluates parameter uncertainty driven by test data. The joint shear constitutive model parameters are primarily influenced by  in stress-strain curve representation, while most parameters of the hypoplastic model have a notable impact. These results enhance comprehension and enhance the predictive reliability of these two constitutive models.

The current seismic design of buildings often neglects the effects of basement stories and soil-structure interaction (SSI). This study aims to investigate the seismic response of high-rise buildings with varying numbers of basement stories, considering SSI effects both experimentally and numerically under different seismic actions. A similarity coefficient λ (λ = 1:50) is chosen for the shaking table tests of scaled models to mimic the seismic response of actual buildings. Numerical simulations using PLAXIS 3D were established for scaled and real models with and without SSI effects to simulate the complex system. The experimental and numerical simulation results demonstrated high accuracy. Moreover, the selected similarity coefficient of λ = 1:50 adequately represents the real building conditions under various seismic actions. From the experimental and numerical findings, it is noteworthy that SSI and basement stories exert significant influences on the seismic response of high-rise buildings. While most current codes suggest that SSI effects typically reduce the shear force on buildings but increase relative lateral displacement, it was observed that, in certain cases examined, SSI effects elevate both the shear force and relative lateral displacement of the buildings.

Based on the chemical reaction principles of slurry, a two-dimensional simulation method for polymer fracture grouting in soil was developed using the extended finite element method (XFEM), the modified Cam-clay model, and the calculation model for polymer slurry expansion force. The serviceability of this method was confirmed. The study then examined the temporal changes in slurry expansion force, slurry vein morphology, and soil void ratio, while also exploring the influence of grouting hole depth and soil fracture toughness on the expansion process of slurry veins. The results indicate that the expansion force of the slurry increases initially due to the chemical reaction process of polymers, peaks, and then rapidly decreases to stabilize under the interaction of slurry and soil. The development rates of vein length and width are asynchronous: the vein length remains relatively constant while the width linearly increases from crack initiation to the second expansion stage. Subsequent to the second crack expansion, the vein length linearly increases, and the width growth rate tends to slow down. The slurry squeezing effect significantly reduces the soil void ratio in a specific range on both sides of the crack. Perpendicular to the crack surface, the void ratio decreases closer to the center of the grouting hole. Over time, the void ratio decreases. As the crack expands and the expansion pressure decreases later on, the soil’s void ratio on both sides of the crack surface partially recovers and then stabilizes. With increasing grouting hole depth and fracture toughness, the slurry vein length gradually decreases while the width continuously increases, with the change rate of the two remaining relatively constant. The stability time of slurry vein expansion advances with increasing burial depth and delays with increasing fracture toughness.

To address issues related to excessive human influence and prolonged prediction times in rockburst prediction, we propose a rockburst intensity classification prediction model based on automatic machine learning. This model is trained using five automatic machine learning frameworks and evaluated using metrics such as accuracy, precision, recall, and F1-score. Subsequently, we compare the performance of this trained model with results from thirteen common machine learning models. The model developed with the Auto-Sklearn framework achieved a high accuracy of 0.969, while the model created with the Auto-Gluon framework, although having the lowest accuracy among the five frameworks, still achieved an accuracy of 0.927. Rockburst prediction models constructed using AutoML frameworks significantly outperformed traditional machine learning algorithms. The Auto-Sklearn-based model exhibited the highest accuracy. In summary, the optimized model was applied to predict rockburst events at the Shaiqi River phosphate mine, and the predictions were consistent with the actual observations on-site. This indicates that the automatic machine learning-based model for rockburst intensity classification prediction can accurately predict rockburst incidents in real-world engineering settings.

The finite element limit analysis based on strain smoothing provides an effective and highly accurate numerical approach for stability analysis in geotechnical engineering. A novel upper bound limit analysis using node-based smoothed finite element (NSFEM) is proposed to account for the discontinuous kinematic velocity field. By introducing a discontinuous velocity at the soil-structure interface, characterized by nodal velocity jumps between interface nodes, the strain-smoothed domains are reconstructed based on these interface nodes. The plastic dissipation rates of interfaces and strain-smoothed domains are separately calculated according to the Mohr-Coulomb yield criterion and associated flow rule. These criteria and rules are represented as a series of standard second-order cones. Consequently, the NSFEM-based upper bound limit analysis is formulated as a second-order cone programming (SOCP) problem, solvable effectively using the primal-dual interior point algorithm. The proposed method’s reliability was initially confirmed through benchmark problem analysis in geotechnical engineering, revealing that the interface strength between soil and structure significantly influences the failure mechanism and ultimate bearing capacity of structures.