Inclined rigid sliding walls to protect tunnels subjected to reverse faulting

Abstract

Tunnels subjected to reverse faulting are dangerous, experiencing large inner forces and movements. However, there is a lack of effective mitigation measures to protect shield tunnels from reverse faulting. This study proposed a novel mitigation measure, inclined rigid sliding walls, for shallow buried shield tunnels subjected to reverse faulting. Validated numerical modeling is performed to explore the responses of the tunnel, the effects of the walls, and some influence factors. The results show that the walls are effective to protect the shield tunnel from revere faulting. The function of the walls is to release the fault deformation by sliding and develop a relatively stable condition between the walls with less shearing. The walls can decrease the soil pressures, inner forces, and movements of the tunnel. Three possible interaction mechanisms are summarized: hanging wall mechanism, shear mechanism, and footwall mechanism. The walls work best under the footwall mechanism. The detailed protection effects of IRSWs depend on the relative tunnel location, burial depth of the tunnel, the distance between the tunnel and walls, angle of walls, relative depth of walls, and fault dip angle.