Abstract:To investigate the selection of the advancing mode of the double-shielded tunnel boring machines(TBM) in the weak rock masses of “Datong River-Huangshui River”Water Transfer Project,a three-dimensional finite element model is established to simulate the advancing of the double-shield TBM. The failure mechanisms of the weak rock mass under the gripper pads and the interaction between the weak rock masses and gripper pads are investigated. It shows that the gripper pads pressure will cause the shearing and tension failure of the weak rock mass. When the in-situ stress is mainly caused by the gravity and the lateral pressure with coefficient l<1,the gripper pads pressure will probably cause the failure zone extend and large extent tensile failure zone appear. In addition,the critical strength of the weak rock masses is proposed when the pressure extends the failure zones. Under this condition,the single shield advancing mode and the double-shield advancing mode with lower parameters should be adopted. In the deeper depth with the lateral pressure coefficient l≥1,the gripper pads pressure will have limited influences on the surrounding rock masses and even can not cause the failure zone extend,but,the failure zone may be damaged further. In this case,the primary double-shield advancing mode should be adopted when the residual strength of the weak rock masses is high.