Numerical Research Of Landslide Motion Characteristics And Slope Stability Of Excavation And Supporting

The movement characteristics of landslide and slope stability during excavation and supporting process are the hotspots and difficulties at home and abroad scholars. First of all,based on discrete element software EDEM, we studied the velocity, particle collisions, final deposit morphology and structure of rock mass during the sliding process of a debris flow and Maojiagou potential landslide. Then, the slope project of Jinping power cable crane platform was taken as an example to analyze the difference of stress and strain in whether considering unloading effect of excavation. Finally, we calculated the deformation and stability of different excavation and support methods quantitatively. Based on the research above, the main conclusions are as follows:(1) The movement of debris flow can be divided into 3 stages, including start acceleration, high-speed sliding and deposit, with lots of contacts and collisions; the velocity maximum corresponds to the minimum number of contacts, showed that the sparse flow could cause little energy dissipation, but great speed; regions of the particles with high speed of level and vertical, while the transverse velocity is small; at the early and late stages,horizontal and vertical velocity reduced, but the transverse velocity increases obviously,which could expand the scope of the disaster;(2) Through the potential unstable rock landslide forecasting of Maojiagou in Kangding,moving process can be divided into three stages, including instability stage 0s-30 s,accelerated sliding stage(30s-75s) and slow accumulation stage(75s-140s). In the early, rock collapses appearing at the local; at accelerate sliding stage, motion velocity increased significantly, with large kinetic energy and strong destructive power; when landslide move to the valley, velocity decreases and rocks deposit gradually. The front and middle part of the landslide move with a high speed and deposit at the end of the valley, but due to blocks, most of the back rock mass deposit in the upper position. In the course of the movement, the rock mass damage increases gradually, and the middle of the rock mass appears through cracks.After the landslide, the small rock blocks are located in the upper reaches, with the larger rocks deposit at the lower;(3) Through the excavation process simulation of the case of high and steep slope, we conclude that the unloading could influence the stability greatly. When with considering the unloading, the slope stress relaxation phenomenon is more obvious, even appeared tensile stress; also with greater displacement and smaller safety coefficient; therefore, it is suggested taking unloading into consideration when simulate the rock excavation which is more reasonable to the real. In addition, the shear strain increment is used as the unloading relaxation criterion, which can determine the influence range of excavation unloading quickly,the method is simple and reliable.(4) Single stage excavation height, rock mass strength parameters and the support time have significant influence on the deformation and stability of the slope. Single-stage excavation height influences displacement and stability greatly for poor litho logic slope;however, the strength parameters of rock mass influences displacement and stability obviously during the slope excavation, the time of supporting also plays an important role;and the slope could keep stable when reinforced in time after excavation. In the actual high and steep slope project, reasonable excavation height and support measures should be adoptedwhich is helpful to ensure the slope stability and reduce the cost.