Numerical Simulation Study On The Influence Of Safety Pillar To Rock Mass Stability In Open-stope Mining Process

The problems associated with underground mined-out area have become one of the restrictive factors of the sustainable development of mines; once open-stope mining method is used, plenty of mined-out areas would be left. Therefore, it is very important to do some research on rock mass stability for those mines using open-stope mining method.Taking Xiaobanlong mining area of Xingtianling Tungsten Co.Ltd as the engineering background, based on the development situation in the related fields at home and abroad, the data collected in the mine and the on-site geological conditions investigated, the thesis adopted laboratory experiment, engineering analogy and numerical simulation analysis method to study the physical and mechanical parameters of rock mass, face-and-slab mining sequence and the influence of safety pillar on rock mass stability respectively. The main research contents of this thesis are listed as follows:(1) Through laboratory rock mechanical experiments, the physical and mechanical properties of the ore, granite and limestone in Xiaobanlong mining area were studied and the related parameters were obtained, on the basis of which mechanical parameters of the rock mass were estimated and calculated in use of Hoek-Brown criterion based on GSI system.(2) Based on the general stoping planning for the orebody, the surrounding rock mass, oreboby, room and pillar models were established by ANSYS software and after being transferred into FLAC3D software, the models simulated the initial stress field in rock mass in Xiaobanlong mining area.(3) Upward and downward open-stope mining process in Xiaobanlong mining area were simulated respectively, from which the variation law of stress and displacement was obtained and proper face-and-slab mining sequence was determined.(4) Rock mass stabilities of three different stoping sequences, that is, retreating without safety pillar, retreating with one safety pillar and retreating with two safety pillars, were discussed in Xiaobanlong mining area. The simulation results reveal the distributions of stress, displacement and plastic zones, as well as the influence of safety pillar on rock mass stability. At last, some constructive control measures were proposed according to the simulation results.