Introduction Gas migration in low-permeability buffer materials is a crucial aspect of nuclear waste disposal. This study focuses on Gaomiaozi bentonite to investigate its behavior under various conditions.Methods We developed a coupled hydro-mechanical model that incorporates damage mechanisms in bentonite under flexible boundary conditions. Utilizing the elastic theory of porous media, gas pressure was integrated into the soil's constitutive equation. The model accounted for damage effects on the elastic modulus and permeability, with damage variables defined by the Galileo and Coulomb-Mohr criteria. We conducted numerical simulations of the seepage and stress fields using COMSOL and MATLAB. Gas breakthrough tests were also performed on bentonite samples under controlled conditions.Results The permeability obtained from gas breakthrough tests and numerical simulations was within a 10% error margin. The experimentally measured gas breakthrough pressure aligned closely with the predicted values, validating the model's applicability.Discussion Analysis revealed that increased dry density under flexible boundaries reduced the damage area and influenced gas breakthrough pressure. Specifically, at dry densities of 1.4 g/cm3, 1.6 g/cm3, and 1.7 g/cm3, the corresponding gas breakthrough pressures were 5.0 MPa, 6.0 MPa, and 6.5 MPa, respectively. At a dry density of 1.8 g/cm3 and an injection pressure of 10.0 MPa, no continuous seepage channels formed, indicating no gas breakthrough. This phenomenon is attributed to the greater tensile and compressive strengths associated with higher dry densities, which render the material less susceptible to damage from external forces.

During penetration into large-sized multimedium materials, shaped charge jets are affected by jet fracture and interface effect, leading to reductions in their penetration performance. A theoretical model and calculation method for the penetration of shaped charge jets into asphalt/soil/concrete composite targets were established and experimentally verified to explore the law of the jet-induced damage of large-sized multimedium materials. The influence of the shaped waves generated during the penetration of shaped charge jets, jet fracture, and the interface effect at the interface between different media on the penetration performance of shaped charge jets were taken into account. The theoretical calculation results are in good agreement with the test results. In addition, through dimensional analysis and theoretical calculation, the curve chart of the relationship between total penetration depth and asphalt/soil part thickness is obtained. This chart can quickly reflect the law of the penetration of shaped charges into media with differing thicknesses.

Cut-fill interfaces within the loess subgrade tend to form potential failure surfaces, controlling the mechanical properties of cut-fill engineering. Focusing on the cut-fill interface, extensive laboratory tests in this research show the performance of interfacial mechanical properties under various test conditions, revealing interface effects and exploring the impact of different factors on these effects. The results indicate that the interface strengthens the friction angle of soil but weakens cohesion, especially impacting the cohesion, thereby reducing the shear strength of soil. The increase in dry density diminishes the enhancement effect on friction angle caused by the interface while amplifying the degradation effect on cohesion. Elevated water content has a weak influence on the enhancement effect of friction angle but diminishes the degradation effect of cohesion. Load doesn't change the impact of dry density on the interface effect but amplifies the impact of water content. The impact of various factors on interfacial shear strength manifests as follows: load > average dry density > water content. The interaction among these factors demonstrates average dry density + load > water content + load > average dry density + water content. The study indicates that the construction of loess subgrades based on the standard of maximum dry density and optimum water content may not align with the conditions required for achieving optimal stability at the cut-fill interface. These research findings reveal the crucial role of various factors in comprehensive impact of interfacial effect, offering essential support for ensuring the stability of cut-fill interfaces.