This paper introduces a three-phases model based on the finite element method to simulate the generation and propagation of landslide-generated impulse waves, and this model can be employed to predict and prevent wave-induced hazards. The fluid-like landslide mass is treated as a non-Newtonian viscoplastic fluid. The motion of landslides, water and air is modelled by the incompressible Navier-Stokes equations and the interfaces between these three phases are captured with the n-phases improved conservative level set method which can preserve mass and provide precious interface parameters, including normals and curvatures. The conservative feature of this method is proven by the threephases Zalesak slotted disk test case. This method is then adopted to simulate the impulse wave generated by the Lituya Bay landslide and the current outputs are compared with other existing results. Finally, this verified model is utilized to model the impulse waves generated by the Halaowo landslide near the Xiangjiaba Dam in the Jinsha River and the results could provide references for further protective activities.

Summary A new 2‐dimensional discrete element method, which is able to simulate a system involving a large number of arbitrary convex elements, is proposed. In this approach, a novel distance potential function is defined using a normalized format of the penetrated distance between contact couples, while a holonomic and precise algorithm for contact interaction is established, accounting for the influence of the tangential contact force. Furthermore, the new contact detection algorithm is well suited for nonuniform blocks unlike the common no binary search method that requires uniform elements. The proposed method retains the merit of the combined finite‐discrete element method and avoids its deficiencies. Compared with the existing finite‐discrete element method, the distance potential function has a clear physical meaning, where the calculation of contact interaction avoids the influence of the element shape. Accordingly, the new method completely gets rid of the restraint of uniform element type and can be applied to arbitrary convex elements. The new method is validated with well‐known benchmark examples, and the results are in very good agreement with existing experimental measurement and analytical solutions. Finally, the proposed method is applied to simulate the Tangjiashan landslide.

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