Coupled CFD-DEM simulation of progressive failure of tunnel face

Extensive studies have been conducted to investigate the face stability of tunnelling by the discrete element method (DEM). However, the DEM simulation of tunnel face’s failure considering water-soil interaction has not yet been available. In this paper, the coupled CFD-DEM method was adopted to simulate the progressive failure of the shield tunnel face in saturated sand, and the tunnel’s failure in dry sand was also simulated for comparison. The dynamic mesh method was introduced to accurately simulate the CFD domain’s variation due to the movement of the tunnel’s face. The excavation face was moved forward or backward at a uniform displacement rate to simulate a passive or active failure, respectively. The ground surface movement and supporting force of tunnel face were analyzed to investigate the feature of tunnel face failure in saturated and dry sandy soils.