Face stability analysis of EPB shield tunnel in sand

When an earth pressure balanced (EPB) shield tunnel is constructed in sand which is weakly self-stabilized, face failure may occur if the support pressure in the chamber is not strong enough, and much attention should be paid to it. The three-dimensional discrete element method (3D DEM) is employed to analyze the face stability when the shield is being advancing or stopped. Precise EPB shield machine models are established and the dynamic construction process is incorporated. Thus, the influence of soil-cutting tool interaction and support of panel for face soil can be considered. The impact of cutterhead types, buried depth and rotating speed of cutterhead on the limit support and pattern of failure zone can be clarified, and the failure mechanism of EPB shield tunnel in sand can be explained microscopically. Compared with the existing researches, the dynamic construction process is considered to study the face stability in this study, which is close to tunnel construction in practice. The study results may serve as certain guidance for guaranteeing the face stability of EPB shield tunnel in sand.