This study investigates the water pressure distribution and deformation patterns in tunnel linings within water-rich tunnels traversing fault zones, focusing on the Gudou Mountain Tunnel. The study utilized field tests and numerical simulations to assess the water pressure distribution around test sections. Following the confirmation of consistent water pressure distribution patterns from field tests and simulations, we analyzed the deformation patterns of tunnel linings at various water levels. The results showed that water pressure is highest at the tunnel’s inverted arch and arch foot, moderately high at the vault and spandrel, and lowest at the arch waist. The sections RK51 + 590 and LK51 + 640, located on opposite sides of a fault crush zone, experience high fragmentation of surrounding rock. This allows rainfall and reservoir water to seep through fractures, causing increased water pressure and significant deformation at the inverted arch of these sections. With rising groundwater levels, deformation intensifies at the inverted arch, arch foot, and vault. The appearance of macro-cracks in these critical areas leads to groundwater seepage through the cracks, severely impacting tunnel operations. Consequently, reinforcing the inverted arch, arch foot, and vault is crucial to reduce the risk of water leakage in the tunnel.

Liquefaction-induced failure of pile foundations remains a critical challenge in seismic bridge engineering, particularly for large-diameter variable-section piles widely used in deep foundations. To address the limited understanding of their dynamic behavior in liquefiable soils, this study conducted large-scale shaking table tests on single and group pile foundations at the Xiang’an Bridge site in Xiamen. The model reproduced a stratified saturated sandy soil profile to examine pore pressure evolution, acceleration response, horizontal displacement, and bending moment under seismic intensities of 0.15 g, 0.25 g, 0.35 g, and 0.45 g. The experimental results validated the model’s reliability and revealed clear performance distinctions between the two pile types. As seismic intensity increased, the stable pore pressure ratio rose from 0.72 to 0.86, indicating progressive liquefaction. Compared with the single pile, the pile group exhibited 15–25% lower peak acceleration and displacement, and a delayed occurrence of maximum response by about 1.3 s. Damage occurred at 0.35 g for the single pile but only at 0.45 g for the pile group, accompanied by a more minor reduction in fundamental frequency (32.44% vs. 52.90%). These results demonstrate that the pile group effect mitigates the impact of liquefaction and enhances seismic resistance. The study provides experimental validation and quantitative insight into the dynamic response mechanisms of variable-section pile group foundations, contributing novel guidance for the seismic design of bridge foundations in liquefaction-prone regions.

For culverts installed in soft soil, the rigid composite pile foundation is used for soil treatment, and the stresses around the culverts are complicated. Centrifuge experiments and numerical simulations are conducted to investigate the vertical earth pressures and soil settlement over a slab culvert under high backfill in soft soil, and the foundations are treated with rigid composite piles. The influences of lateral pile length and pile spacing on the earth pressures at the top of the culvert are analysed, and they have significant effects on the vertical earth pressure coefficients. It also indicates a strong correlation between the backfill height and the vertical earth pressure coefficients. For a high-backfill culvert, there is a uniform settlement surface where the settlement of the interior and exterior soil prisms is at the same level. According to the experiments, the height of the uniform settlement surface and the vertical earth pressures decrease with increasing the lateral pile length and pile spacing. Numerical simulations were conducted using finite element software Midas GTS to evaluate the performance of the experiments. Further, recommendations for selecting an appropriate pile composite foundation for slab culvert in soft soil are provided.

In order to study the bearing characteristics and failure mechanism of the rigid antislide pile under horizontal load, the stress of rigid antislide pile under transverse axial large displacement load is analyzed by using elastic-plastic theory, finite element analysis, and model test. The theoretical formula of the proximal plastic earth pressure near the pile with the depth of soil under the horizontal force is obtained. The results show that the standard is insensitive to the variation of soil parameters and the influence of soil parameters on allowable soil resistance in front of pile should be considered. With the increase of the horizontal force of the pile top, the soil near the pile is destroyed in this process gradually, which is the decline of the cross section of the maximum soil resistance of the pile. When the horizontal displacement of pile top is 20mm and 70mm, the soil resistance value and the ultimate soil resistance value in front of the pile can be selected, respectively. The plastic zone develops to the front and bottom of the pile at the same speed, at an angle of 45 with the direction of gravity. When the displacement reaches 34mm, the plastic zone develops to the deeper depth obviously. The results can provide a theoretical basis for the design and application of antislide piles during the process of slope protections.