(1. Institute of Geomechanics，Chinese Academy of Geological Sciences，Beijing 100081，China；2. Key Laboratory of Active Tectonics and Geological Safety，Ministry of Natural Resources，Beijing 100081，China；3. China Institute of Geological Environment Monitoring，Beijing 100081，China；4. School of Geology Engineering and Geomatics，
Chang?an University，Xi?an，Shaanxi 710061，China)
Abstract：The movement process of high-position and long-runout landslides is complex and the sliding main body is changeable. The dynamics theory of post-failure and inversion prediction technology have always been the focus and difficult problems in the field of disaster prevention and reduction. In this paper，the dynamic process of polymorphic transformation based on the degree of density in the movement of high-position and long-runout landslide is revealed by survey analysis，theoretical research and numerical technology development. Based on SPH and DEM algorithm and dynamical constitutive model transformation，a new numerical simulation method for landslide post-failure motion(LPF3D) is presented. The results show that：(1) Through the analysis of actual landslide video and grains chute experiment recording，it is found steric effect which the grains motion in the process of landslide movement mainly present the dense state，dilute state and ultra-dilute state，and the grains state changes and transforms with each other at all times. (2) The volume fraction is used as the criterion of discrete grains number and grains state transformation，and the numerical calculation method and critical volume fraction is proposed to solve different states in landslide movement based on different dynamical constitutive models. (3) The macroscopic continuum algorithm based on the theory of polymorphic transformation is used in the inversion of the debris flow of Jiweishan landslide in Wulong，Chongqing，and the simulation results are basically consistent with the actual landslide accumulation. (4) The LPF3D simulation method achieved the transformation of grains state and the efficient calculation of the actual number of grains in the calculation of landslide failure movement，and improves the convergence stability of the calculation，which has great computational advantages. Based on the above research，it is believed that in the risk investigation and dynamic process analysis of high-position and long-runout landslide flow，the influence of the state changes of sliding body grains and the actual number of grains should be fully considered. The LPF3D simulation method provides an efficient，quantitative and optional method for the risk assessment and prediction of high-position and long-runout landslide.
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2023, Vol. 42 
