MOVEMENT CHARACTERISTICS AND RISK ASSESSMENT OF MINE DEBRIS FLOW BASED ON FLO-2D SIMULATION: A Case Study of the Debris Flow in Bojigou Mine of Minxian County, Gansu Province

The human mining activities in Bojigou gold mine of Minxian County cause debris flow. The FLO-2D software is used to simulate and analyze the movement characteristics of Bojigou debris flow under the frequency of rainfall return periods of 50 a and 100 a. On this basis, the risk assessment and zoning are carried out, and the accuracy is verified by actual situation. The results show that parameters of movement characteristics such as the range of alluvial fan, accumulation depth and average velocity of debris flow increase with the increase of rainfall return period. The accumulation depth and velocity in the middle part of alluvial fan are significantly larger than those in the wings and front end. The hazardous areas of debris flow are concentrated in a certain range at the gully and gully mouth. The proportion of high risk area increases from 48% to 54.0% with the longer rainfall return period. The simulation results are basically consistent with the actual situation through accuracy verification, which are reliable in application.