Abstract: A soil slope failure usually experiences the initiation, development, and run-through of the slip plane. The extended finite element method (XFEM) has been applied to simulate the process of slope failure in recent years. However, there are still some shortcomings to be overcome in practical applications of XFEM to landslides. For example, the initial position of the slip plane needs to be prescribed, and the extending direction of the slip front-end cannot be tracked accurately. In this paper, the mechanism of slip-plane initiation and development is introduced, and the process of automatically determining the initial position of the slip plane based on the stress history and the relative relationship between the tensile stress level and the shear stress level in the soil element is proposed and described in detail. Then, a new method for determining the front-end propagation direction of the slip plane by using the sector control domain and the circular control domain is introduced, which effectively improves the simulation precision of the XFEM for the landslide failure process. Finally, two typical slope cases with different failure types are analyzed to verify the reliability and rationality of the proposed method further.

Key words: extended finite element method (XFEM), landslide, slip plane, initiation, development