Research On Distribution Of Stope Floor Rock Stress And Evolution Law Of Mining Fissure In Short-interval Thick Coal Seams

According to the specific geological conditions of a mine in Pan-Xie mine area in Huainan, and floor rock mass under the interaction of abutment pressure and hydraulic pressure in short-interval thick coal seams, it is studied that the stress distribution and evolution law of mining fissure in floor rock mass by applying the integrated research method of combining theoretical analysis and numerical simulation and similar simulation.In the aspect of theoretical analysis, the mechanical model of coalface during primary mining and normal stoping was established, by applying the theory of semi-infinite plate body in elasticity, and the stress distribution of any point in mining floor rock mass under the interaction of abutment pressure and hydraulic pressure. Meanwhile, based on corresponding formulae, the maximal and smallest principal stress were got. The depth and scope of floor fracture development were judged out with Mohr-Coulomb criterion. On the basis, the main factors influencing the fracture development depth were studied and the expression of the influence factors and the fracture development depth was given.In the aspect of numerical simulation, A three-dimensional numerical Fluid-Solid Coupling model was established when face stoping with FLAC3D numerical simulation software. The stress distribution and displacement variation law in different depth of mining floor in short-interval thick coal seams which use the two recovery methods of mining overall height in one times and slice mining during coal mining process were studied. At the same time, the difference of the stress distribution in the two recovery methods was analysed.In the paper, the simulation experiment system studying on the floor fracture evolution law when mining on the top of water-pressured was designed. Using the experiment system, the dynamic process of the occurrence and extension and transfixion of floor rock mass mining fissure which use the two recovery methods of mining overall height in one times and slice mining were got. At the same time, the stress and displacement distribution of the floor rock mass were measured.The research results can provide theoretical references for the field, and at the same time, meanwhile, the results also have certain reference value for safe mining of A-group seam which was threatened by confined water in Pan-Xie mine area in Huainan. Figure [58] Table [4] Reference [71]...