Study Of Falling Rock Motion Characteristics And Dynamic Response Of A Shed Cave-barrier Wall Based On The Coupling Of PFC^3D And FLAC^3D

In recent years,with the rapid development of China’s economy and the implementation of the"Belt and Road Initiative"strategy,human engineering activities have gradually advanced to mountainous areas.There are a lot of rocky steep slopes in mountainous areas,which cause rockfall disasters from time to time and pose a serious threat to traffic safety.This paper intends to rely on the new Qianjiang-Zhangjiajie-Changde railroad project to study the dangerous rockfall at the Wojiacun station.For the line due to the topographic relief,steep rock walls,bedrock exposure,geological hazards prominent,dangerous rock fall adverse geological hazard of the line is more serious characteristics.The 3D slope modeling is carried out by using the UAV tilt photography technology and the regional geological survey data,and the discrete element method and the discrete element-finite element coupling method are used to study the 3D motion characteristics,the dynamic response of the protective structure and the optimization of the protective structure of the scaffold cavern-barrier wall after the destabilization of the dangerous rock body in the study area,so as to provide reference for the prevention of dangerous rock fall in the study area.The main research contents and results of this paper are as follows.（1）The UAV tilt photography measurement technology is introduced and combined with digital image processing technology.The data obtained by scanning the high and steep slopes in the study area with the UAV,and finally obtained a high-precision 3D model of the survey area through post-point cloud processing and 3D modeling.（2）Through field geological survey and tilt photography technology,the distribution of dangerous rocks in the study area was initially determined,and then the software PFC^3Dwas used to simulate the movement path of the dangerous rock body,analyze its accumulation law,and discuss the characteristics of its movement speed,movement trajectory,movement energy and lateral deflection.（3）A discrete element-finite difference coupled calculation method is used to analyze the scaffold cavern-rock barrier wall structure in the study area under the impact of falling rocks with different shapes,sizes,impact velocities and angles.（4）Using the discrete element-finite difference coupled calculation method,effects of the buffer layer on the impact resistance of the shed roof and buffer bedding thickness,material type,compaction degree and gradation is analyzed and discussed.It provides a reference basis for the selection of optimal shed roof thickness and buffer material in engineering practice.