Research on Landslide Development Mechanism of Loose Accumulation Slope under Earthquake Condition

摘要

Loose accumulation slope is widely distributed in southwest China. Compared with conventional soil and rock slope, the stability of such slope is poorer and the deformation and failure mechanism is more complex. In addition, the stability problem under the earthquake condition is especially prominent. In this paper, an accumulation slope in Chongqing is taken as an example. By utilizing the particle flow code (PFC), the wave propagation equivalent relationship in the continuous medium and the discrete medium is established under the condition of the ground motion peak acceleration as O.lg, 0.2g, 0.4g, and 0.6g, respectively. The dynamic boundary conditions under earthquake condition are analyzed as well. The movement and deformation of the particles in the accumulation slope are analyzed during a short period of 30 s. Based on the analysis of the displacement field, the velocity field, the stress field, and the change of slope micro structure, such as porosity and coordination number, structural damage accumulation characteristics, and failure mechanism of loose accumulation slope are explored. The results show that the landslide hazard analysis method based on discrete element method can reflect the process of degradation and instability of loose accumulation slope accurately. The weak links in the accumulation body damage gradually and the particle displacement develops from the bottom to the top of the slope. Under the difference in dynamic response between the overlying accumulation body and the lower bedrock, the slope damage is exacerbated and the cracks are rapidly expanded until it perforates, and the surface of the slope exists local collapse in a certain degree. Under different ground motion peak acceleration, the failure mechanism of accumulation slope is similar, but the scale of damage is different.