Predictions For Deformation Failure Of The End Slope Of An Open Pit Resulting From Mining SteepUltra-thick Iron Ore Bodies

The mining of ore bodies on the end slope of an open pit will help induce the deformation of and the damage to the slope. To deal with this problem, the reasonable predictions of slope failure can effectively avoid the damage from landslides. In this paper, Yanqianshan Iron Mine is taken as a case study, and the Discrete Element Method (DEM) is used to predict the deformation failure of a slope, which is induced by mining steep ultra-thick iron ore bodies on the end slope of its open pit.The main work and achievements are as follows:(1)The three-dimensional geological modeling system, RockModel, which is independently developed by us, and the software3DEC are used to build a computational model that considers the complex geological interface and the distribution characteristics of the joints. According to the results of laboratory rock mechanics experiments and a statistical analysis of on-site joint features, the mechanical parameters of the simulated rocks and joints are determined.(2)The measured data of the characteristics of slope failure caused by mining ore bodies on the first layer (elevation range of-51m to-69m) on the eastern end slope and the3DEC results for a mining simulation are compared to verificate the computational model and the mechanical parameters validity.(3) Based on these results, the mining of ore bodies on the second to the fourth layers (elevation ranges of-69m to-87m,-87m to-105m,-105m to-123m) on the eastern end slope is simulated in order, and the deformation and destruction behaviors on the mine pit slope during the mining process is predicted.The following conclusions according to the numerical simulation results show: With the gradual increase of the mining depth, the surrounding rocks at the top of the mined-out area constantly collapse; and the rocks on the south and north sides slide along two groups of dominant joint planes into the mined-out area,respectively. The slope surface above the mined-out area produces subsidence and slides into the pit, with the slope surface on the north side moving southwest and the slope surface on the south side moving northwest. The cracking range on the slope surface gradually expands, and the range of destruction on the north side is always greater than that on the south.