The analysis for characteristic of particles movement and pressure balance stability in the shield soil chamber during the EPBS excavation in weathered diorite stratum

Abstract

The number of face failure accidents are mainly due to adequate soil chamber pressure particularly for the earth pressure balance shield (EPBS) tunnel excavation in rock stratum. In this paper, a series of laboratory tests and numerical simulations is firstly conducted to investigate the physical and mechanical parameters of weathered diorite. Considering the impact of rotation of screw conveyor and transmission of elements, the dynamic response of diorite particles and interaction between chamber and support pressure are obtained and analyzed by the discrete element method (DEM) model. The results indicate that the diorite particles movement path is relevant with the inclination of the screw conveyor based on the stack simulations and field tests, which leads to the arching effect contributing to a smaller working pressure at the central area of the chamber than around the arch boundary. Additionally, the pressure transfer coefficient α is introduced to characterize the relationship between the support pressure and shield working pressure, which provided valuable references for the setting of soil chamber pressure in projects.