In rock-lined caverns with compressed air energy storage (CAES), the hoop tensile strength of rock is an important parameter for calculating the ultimate bearing capacity and long-term stability of the cavern. The existing methods for measuring the tensile strength of rock are direct tensile tests or indirect tensile tests, such as Brazilian splitting and point load bending tests, which cannot truly reflect the circumferential stress of rock under high internal air pressure. Based on this, a new measurement method is proposed. By injecting high-pressure air into the drilled rock sample, the rock burst pressure is obtained. Then a calculation formula for the rock tensile strength is proposed considering the rock pore stress. In the experiments, the inflation rate and the temperature are changed, and it is found that the rock burst pressure is negatively correlated with the inflation rate and positively correlated with the temperature. It is found that when the number of cycles is relatively small (n≤100), the rock burst pressure is positively correlated with the number of cycles. The results can guide the design and calculation of rock-lined caverns for CAES, which is conducive to the promotion and application of CAES technology and has important engineering application value.

To study the wetting deformation characteristics of undisturbed loess under true triaxial force-water path, the true triaxial apparatus with rigid-flexible-flexible loading boundary was used to carry out the true triaxial single-line humidification test of undisturbed loess in Xi'an under different spherical stresses, intermediate principal stress parameters and stress ratios. The influence of true triaxial force-water path on the humidification deformation characteristics of undisturbed loess was comprehensively analyzed. The test results show that the relationship curve between the wetting volumetric (deviatoric) strain and the spherical stress presents a three-stage of slow-steep-slow. When the spherical stress is in the second stage, the wetting collapsibility of the soil is the largest, and a large wetting deformation can occur. At a certain stress ratio, the wetting volumetric strain gradually increases with the spherical stress, and the increase of the wetting volumetric strain decreases when the spherical stress exceeds 200 kPa. Finally, the variation law between the intermediate principal stress and each humidification strain is analyzed, and the calculation expression of loess collapsible deformation considering the intermediate principal stress is given according to the test results.

Mining disturbance can easily aggravate the creep instability of roadway surrounding rock, and its propagation mode in surrounding rock is damped oscillation disturbance. In order to explore the creep characteristics of rock under the damped oscillation disturbance, X-ray diffraction, nuclear magnetic resonance and pseudo-triaxial creep tests were carried out. Based on the test results, a discrete element numerical model of sandstone was established. The parameter calibration results show that the combination of linear parallel bond model and Burgers model can simulate the creep behavior of rock. Combining the sinusoidal disturbance function with the exponential function, a function expression for simulating the attenuation oscillation disturbance is proposed. The application of attenuation oscillation disturbance in numerical simulation is realized by Fish language, and the creep process of sandstone under attenuation oscillation disturbance is simulated. The simulation results show that compared with the undisturbed rock sample, the accelerated creep time of the rock sample under the action of attenuation oscillation disturbance is earlier and the creep deformation is larger. Before and after the disturbance is applied, the distribution of crack dip angle changes from concentration to dispersion, and the failure mode is tensile-shear composite failure mode. When the attenuation oscillation disturbance is applied, the creep deformation of rock shows a similar attenuation oscillation trend. The greater the deviatoric stress, the greater the influence of attenuation oscillation disturbance on rock deformation. The application of attenuation oscillation disturbance is more likely to lead to the fracture of contact bond between particles and accelerate energy dissipation. The attenuation oscillation disturbance element and the nonlinear viscoplastic body are introduced into the Burgers model, and an improved Burgers model is established. The theoretical curve is in good agreement with the experimental data. The model can better characterize the creep process of sandstone under attenuation oscillation disturbance.

Based on the dynamic theory of elastic media, the horizontal vibration of end-bearing piles embedded in a transversely isotropic soil is studied via an analytical scheme. By introducing displacement potential functions, the governing equations of the soil are decoupled, and the general solutions for the displacement and stress fields around the pile are derived using the method of separation of variables. Applying the continuity conditions at the pile–soil interface, the horizontal complex impedance of the surrounding soil is incorporated into the motion equation of the pile, leading to analytical solutions for the displacement, rotation angle, bending moment, and shear force of the pile. In addition, explicit expressions for the horizontal, rocking, and coupled horizontal–rocking dynamic impedances at the pile head are derived. Comparison with existing theoretical solutions confirms the accuracy and reliability of the proposed method. Furthermore, the influence of soil anisotropy parameters on the horizontal vibration characteristics of the pile is systematically analyzed. The results indicate that the anisotropic modulus ratio has a significant impact on the dynamic impedance at the pile head, as well as on the distribution of horizontal displacement, rotation angle, bending moment, and shear force along the pile depth.

The strength and deformation characteristics of rockfill materials are known to be closely related to their gradations. In order to predict the mechanical behavior of rockfill materials with different initial gradations, the influence of gradation on the mechanical properties of rockfill materials is first discussed within the framework of critical state constitutive theory. Subsequently, a method is proposed for rapidly predicting the initial and critical state void ratios for given gradations. Finally, by incorporating a state-dependent elastoplastic constitutive model, a prediction method for the gradation-related mechanical characteristics of rockfill materials is established. The results indicate that a good linear relationship exists between the minimum void ratio e_min and the critical state void ratio e_cs under low-stress conditions. Utilizing a particle packing algorithm, the critical state position of rockfill materials with specific gradations in the void ratio-pressure (e-p, e is the void ratio of the rockfill material in its current state, and p is the mean stress) space can be reliably predicted. Ultimately, this proposed prediction method facilitates the calibration of constitutive model parameters based on the test results of rockfill materials with known gradations, which subsequently allows for effective prediction of the mechanical behavior of other rockfill materials with different specified gradation profiles.

Evaluating the compaction quality of rock-filled subgrades rapidly and accurately poses a pressing challenge in highway engineering. To address this, this study establishes a discrete element-finite difference coupling model to simulate the response of rock-filled subgrades under impact loading. The primary parameters of the model are calibrated using indoor large-scale triaxial tests, and the model's accuracy is verified through comparisons between calculated and field data. Furthermore, this study conducts an in-depth analysis of the dynamic response results of five commonly used gradations of rock-filled subgrades under varying degrees of compaction, discussing the influence of gradation fractal dimension and porosity on subgrade deformation response. The findings are as follows: (1) A good exponential relationship between subgrade porosity and resilient modulus is identified, and the concept of settlement ratio is introduced, with a linear relationship between settlement ratio and subgrade porosity being verified. It is suggested that both resilient modulus and settlement ratio should be used as control indicators when evaluating subgrade compaction quality. (2) A prediction function for subgrade resilient modulus considering fill gradation and porosity is obtained, revealing that particle gradation has a significant impact on resilient modulus. Specifically, as the gradation fractal dimension approaches 2.31, the resilient modulus increases more rapidly with decreasing porosity. (3) A settlement ratio of zero corresponds to the ideal compaction state of the subgrade. This study establishes a prediction model for the critical resilient modulus of the subgrade in its ideal state, considering fill gradation, and finds that the critical modulus first increases and then decreases with increasing fractal dimension D, reaching a maximum when D=2.34. These findings aim to provide new methods and theories for evaluating the compaction quality of rock-filled subgrades in engineering.

To investigate the stability of the excavation face during tunnel traversal through an upper-sand-lower-clay composite stratum, centrifugal model tests and numerical simulations were combined to analyze the displacement variation in instability zones, profile characteristics of final instability zones, earth pressure evolution patterns, and ultimate support pressure under different stratigraphic boundary positions and burial depth ratios. Test results indicate: Significant instability occurs when the stratigraphic boundary is at the tunnel face center, while stability is maintained when the boundary is at the tunnel crown. Displacements concentrate in the upper sandy layer with negligible changes in the clay layer, demonstrating that initial instability disturbance influences subsequent instability zone development. Analysis of normalized vertical earth pressure and excavation face retreat displacement curves reveals that increased burial depth ratios and clay layer thickness enhance formation resistance to disturbances. Support pressure ratio-displacement curves for two instability cases exhibit three distinct stages, with the upper side central point of the excavation face reaching ultimate support pressure first. When the burial depth ratio increases from 1.0 to 1.5, the ultimate support pressure shows minimal change. 3D finite element simulations of the excavation process validate the ultimate support pressure, failure patterns in instability zones, and earth pressure evolution, with numerical results showing good agreement with experimental data.

Vacuum preloading, as a widely adopted ground improvement method for saturated soft soils with high water content, is extensively applied in large-scale coastal reclamation projects. However, post-reinforcement bearing capacity remains insufficient in many engineering cases, particularly with limited strength improvement in deep soil layers. Numerous studies have demonstrated that the consolidation efficiency of vacuum preloading is constrained by two critical factors: depth-dependent attenuation of vacuum pressure and fine particle enrichment-induced clogging of drainage paths near prefabricated vertical drains. To address these challenges, this study integrates electro-osmosis with vacuum preloading (EVP) during the later stage of vacuum preloading in the dredger fill project of Yueqing Bay North Port Area. A large-scale model test pool was employed, where conventional vacuum preloading was conducted for 108 days until settlement stabilization, followed by a two-phase EVP intervention. The first phase lasted 11 days, after which electrode polarity was reversed for the second phase (6.5 days), totaling 17.5 days of EVP reinforcement. Post-EVP results revealed significant improvements: at depths of 20 cm, 60 cm, and 100 cm, soil water content decreased by 4.2%,4.84%, and 2.34%, respectively, while vane shear strength increased by 32%, 75%, and 61.1%. The test results indicate that superimposing the electro-osmosis method during the later stage of vacuum preloading can achieve a significant improvement in vane shear strength (with a water content reduction of less than 5%). Particularly for deep soil layers with low initial strength that are difficult to reinforce solely by vacuum preloading, the strength increased by 61%−75%, demonstrating effective reinforcement performance.

The problem of soil cutting widely exists in engineering fields such as tunnelling, port and waterway dredging, geological drilling, and civil construction. Accurately characterizing the three-dimensional soil failure surface in front of the cutting tool during the soil cutting process is of great significance for analyzing soil disturbance states, evaluating tool cutting performance, and understanding soil-tool interaction mechanisms. A nonlinear elastoplastic damage-based constitutive model is employed to describe the deformation and failure process of soil. Based on the characteristics of damage energy dissipation per unit area of the soil medium, a new numerical method is proposed to directly characterize the three-dimensional soil failure surface. Numerical simulations of flat-tool cutting processes under various operating conditions verify the effectiveness and robustness of the proposed characterization method. The influence of cutting angle and depth on the width, rupture distance, soil disturbance area, and shear failure angle of the three-dimensional soil failure surface is discussed in combination with theoretical calculations. Furthermore, the shape of the three-dimensional soil failure surface for complex-shaped tools obtained through this numerical method is consistent with experimental results, further validating the applicability of the proposed method for complex tool scenarios.

This study investigated the dynamic response of a high steep rock slope with a double-layer ductile shear zone using the right bank slope of the Banda Hydropower Station dam site area in the upper reaches of the Lancang River as the research subject. Shaking table model tests were conducted to simulate seismic behavior by incorporating the dimensionless peak acceleration amplification factor for the slope and applying seismic waves of varying types, excitation directions, frequencies, and amplitudes. Experimental results showed that: (1) Increased frequency and amplitude enhanced the dynamic response, with frequency exerting greater influence than amplitude. (2) The slope model exhibited evident elevation amplification within the slope and nonlinear near-surface amplification on the slope surface. (3) Under horizontal seismic loading, thicker ductile shear zones demonstrated pronounced energy absorption and dissipation effects. (4) Under vertical seismic loading, thicker zones continued to absorb energy, while thinner near-surface zones amplified seismic wave amplitudes.