Discrete Element Numerical Simulation Of Rock Movement Induced By Mining Hanging Wall Ore With Hanging Caving Method Under Open-Pit Final Slope

In the later stage of mining activities in open pit mines,the amount of minable ore in the boundary is gradually reduced,and some open pit mines are planned to develop deeper into mineral resources.In the transition period of this development,in the open-pit mine,in order to ensure the smooth and smooth transition of the existing mining methods to underground mining,and to avoid the occurrence of large-scale or reduced production of ore production,it is often considered to hang the resources for mining and recovery.As one of the common methods for mining and supporting mines at home and abroad,the caving method will cause instability and collapse of the open pit slope during the mining process,and the slope damage will be safe for slopes,surface structures and open pit mines.There is a certain degree of influence.Based on the background of hanging wall mining in an open-pit iron mine in Hubei Province,this paper uses PFC^2D?Particle Flow Code 2 Dimension?discrete element numerical simulation software to study the failure modes of goaf and open-pit slope under the influence of different hanging wall inclination,burial depth,sectional height and slope inclination,and to analyze the process of rock displacement and ultimate failure scope of slope.The main research results are as follows:1)Based on the physical and mechanical parameters of rock mass in mines and through the calibration process of macro-and micro-parameters,the Micro-Parameters of particles which can characterize the macro-strength of rock mass in slopes are obtained.According to the current situation of mining,the particle model of open pit slope is established.2)Under the influence of dip angle of hanging wall mine,with the increase of dip angle of ore body,the failure mode of goaf roof evolves from"interlayer tension collapse"to"roof rock mass mass collapse";the failure mode of open pit slope evolves from"pull-collapse"to"collapse-collapse"with the extension of mining depth.After mining the third sublevel orebody,the failure range of the slope decreases with the increase of the dip angle of the orebody;when the dip angle of the hanging wall is less than 45°,the volume of the goaf is smaller than that of the loose rock mass;when the dip angle of the hanging wall is greater than or equal to 45°,the volume of the goaf is larger than that of the loose rock mass.3)With the increase of the burial depth of hanging-wall mine,the damage scope of slope after mining in the third sublevel decreases gradually;when the burial depth of ore body is less than 190 m,the volume of goaf is larger than that of loose rock mass;when the burial depth of ore body is greater than 190 m,the volume of goaf is smaller than that of loose rock mass.4)With the increase of slope dip angle of open-pit mine,the damage scope of slope after mining of the third ore body increases gradually;when slope dip angle is less than 45°,the volume of goaf is larger than that of loose rock mass;when slope dip angle of open-pit mine is greater than or equal to 45°,the volume of goaf is smaller than that of loose rock mass.5)Under the influence of the sublevel height of hanging-wall mine,when the sublevel height of the last sublevel ore body is equal to 15m,the damage scope of open-pit slope is the largest;when the sublevel height of hanging-wall mine is less than 20m,the volume of goaf is smaller than that of loose rock mass;when the sublevel height of hanging-wall mine is equal to 20m,the volume of goaf is larger than that of loose rock mass.