Visco-elasto-plastic simulations for coal pillar stability affected by mining

Many disasters such as rock burst and large deformation of surrounding rock caused by mining action are getting more and more serious. Coal seam is considered as a kind of elasto-plastie-visco material, and FLAC3D software is used to simulate the coal pillar failure and deformation features of three kinds of coal pillar width: 10 in, 5 in and 3 in, which influenced by one side caving. Simulation results show, for the case of coal pillar width of 10 in, that there exists a high concentrating stress core inner coal seam, which may lead to the rock burst disaster when stored energy releases. For the case of coal pillar width of 3 in, the large creep deformation of coal pillar will continue increase because of unstable creep of coal pillar, which will cause the roadway too narrow to be used. But for the case of coal pillar width of 5 in, there is neither high stress core nor large deformation inner the coal pillar, it is suitable for the maintaining coal pillar of roadway. Obviously, the optimum coal pillar width can be determined by considering such factors as the engineering safety, maintaining time as well as cost and so on, based on the coal pillar elasto-plastic theological features. Also, visco-elasto-plastic analytical method is more effective than traditional elasto-plastic analytical method to reveal the distribution of abutment stress of coal seam.