Seismic performance and influencing factors of pile foundation of bridges in permafrost regions

In order to study the seismic performance and influencing factors of the pile foundation of bridges in permafrost regions, the pile foundation of bridges with elevated caps widely used in the permafrost regions of China is taken as the research object. The seismic failure characteristics of the pile foundation of bridges in the permafrost regions, and the influences of the physical and mechanical properties of frozen soil on its seismic performance are discussed by using the quasi-static tests and combining with the finite element method. It is found that the lateral bearing capacity and the initial stiffness of the pile-frozen soil system increase with the decreasing temperature of the frozen soil. The displacement of piles changes significantly before and after soil freezing. The change of the initial moisture content of soil has small influences on the lateral bearing capacity of the pile–frozen soil system and the displacement of piles. Take the optimal moisture content of soil as a boundary, the stiffness changes of the pile-frozen soil system are quite different under both sides of the boundary moisture content. The change of soil compaction degree has small influences on the change of the lateral bearing capacity of the pile–frozen system and the displacement of piles. The initial stiffness of the pile-frozen soil system increases with the increase of compaction degree of soil. Therefore, the physical and mechanical properties of the surrounding frozen soil of piles should be fully considered in the seismic performance evaluation of bridges with pile foundation in frozen soil regions.