Deformation of surrounding soil mass of subway tunnel subjected to traffic loads considering principal stress rotation

Under complex loads such as traffic loads, the foundation soil of transportation infrastructure will bear Principal Stress Rotation (PSR) and ignoring PSR may underestimate the long-term deformation of the foundation soil. However, due to the loading limitations of experimental equipment, traditional experimental research mainly used triaxial apparatus without considering PSR. This article uses the finite element method to obtain stress paths in the soil element directly below the tunnel under subway traffic loads, considering PSR. Based on these paths, Hollow Cylinder Apparatus (HCA) tests on Fujian ISO standard sand are conducted. The axial and shear deformation are compared. PSR significantly impacts the axial deformation but has little effect on the shear deformation. The research results help to more accurately predict the long-term deformation of tunnel surrounding soil under subway traffic loads and improve the safety and economy of the project.