Under the long-term dynamic load influence of trains, shield tunnel structures are damaged. With the increase in operating number, cumulative damage gradually increases. When cumulative damage increases to a certain value, the tunnel lining produces cracks and loses tensile strength, which leads to tunnel deformation, damage, etc. In serious cases, the tunnel ceases operation, causing traffic accidents and casualties. Based on the finite element software ABAQUS, this paper analyses the change rule of tunnel lining damage under long-term dynamic train load and explores the influence of tunnel buried depth on the change rule of tunnel lining damage. The excitation force function is used to generate a series of dynamic and static loads superimposed by sine functions to simulate the dynamic loads of trains. Load is applied above the tunnel by writing DLOAD subprogram. The results show that the damage of tunnel lining mainly occurs at the arch foot and the structural damage in other places can be neglected. Under the same loading condition, the greater the tunnel lining damage is. Under the same loading conditions, the tunnel lining damage increases with the increase in buried depth. According to the test results, the mathematical expressions of cumulative damage value versus loading times at the location prone to fatigue damage. It provides theoretical reference for safety evaluation and protection of tunnel structure under long-term train load.

In order to study the working mechanisms of pile foundations applied to embankment engineering on weak slope foundations, a finite element model of embankment on weak slope foundation reinforced by a pile foundation is established. The influence of the position and the length of the pile foundation on the stability of the embankment is studied, and the mechanical response of the pile foundations are also studied. The results show that the different positions of the pile foundation have great influence on the safety factor and deformation of the embankment. The safety factor varies greatly from one reinforcement location to another. The maximum vertical deformation of the embankment reinforced by the 3 m pile is 27 times that of the 7 m. With different pile lengths, the horizontal displacement of the pile foundation can be significantly reduced by approximately 83.3% at most. The research results may provide more scientific help for the design of embankments on soft soil slopes reinforced by pile foundations.