Post-failure analysis of landslide blocking river using the two-phase double-point material point method: a case of western Hubei, China

Due to the typical topography and hydrological characteristics in western Hubei's mountain and gorge areas, the landslide-surge-barrier dam disaster chain is the prevalent geological disasters. This research describes the blockage of Pingdu River by the Erhuang Village landslide (110 degrees 08 ' 48 '' E, 31 degrees 47 ' 27 '' N) that occurred in Shiyan, causing six deaths and serious damage of hydropower station. In order to reveal the mechanism of this disaster chain, it is critical to reproduce the complex fluid-solid coupling process involved in the disaster. The interaction between landslides and rivers, as the linking process in this disaster chain, basically determines the scale of secondary disasters. Therefore, we adopt the TPDP-MPM to establish the numerical model realistically: two sets of particles represent landslide and water body, respectively. Regarding the sliding surface as a computational boundary, we reproduced the landslide runout and river blockage process. By giving full advantages of TPDP-MPM, the chain generation mechanism of the strong coupling effect of soil-water in the landslide-surge-river blocking disaster chain is decoupled and analyzed from the energy perspective, a new understanding of the chain generation process is obtained, and the movement of landslide disaster chain was divided into three stages: acceleration and ejection, river braking, and accumulation. Besides, the chain generation mechanism and spatial-temporal evolution of the landslide-surge-barrier dam disaster chain, especially the mechanism of river-braking and the coverage of influence of surge, were discussed. This research provides a novel methodology for the reproduction and risk assessment of landslide-surge-barrier dam disaster chain.