Fracture Evolution Law And Gas Migration Characteristic Of Overburden And Underlying Strata In Three Dimensional Mining-induced Stress Conditions

In coal mining process, stress conditions of goaf overburden and underlying strata changed after mining, and stratas produced bending,deformation and shear failure with the advancing of working face. Different bending stiffness of strata caused inconsistent deformation and result in appearance of lateral bed-sperated fissures and vertical cross-measure cracks, thus formed fracture zone of overburden and underlying strata. Fracture zone provided occurrence space for gas from working face, goaf and Adjacent layers, thus influencing the occurrence and flow status of gas. The studies in the past were mostly based on 2-dimensional plane similar physical simulation model experipents and numerical simulation method, while coal mining was in conditions of complex 3D stress, therefore the research of fracture zone evolution regularity in 3D mining stress condition is of great significance. In this article, through similar simulation experiment in 3D stress conditions and numerical simulation method, researched mining damage regularity, fracture zone development characteristic and gas migration law. The concrete contents are as follows:① Using “Multi-field coupling of coal mine dynamic disaster simulation test system”, by powering on electric leaves to simulate coal seam mining process, carried out physical mining simulation experipent in 3D stress conditions;② According to the geological data of 2481 working face in Baijiao coal mine of Sichuan Coal Industry Group, carried out simulation excavating experiment in 3D mining-induced stress condition and revealed the dynamic stress condition characteristics, deformation regularity, fracture distribution characteristics and mining-induced damage depth of floor strata;③ According to the geological data of 24080 working face in Pingdingshan coal mine, carried out 3D simulation excavating experiment and revealed the dynamic stress condition characteristics, strata deformation movement rule and fracture distribution characteristics of overburden strata;④ According to fractal geometry theory, to count up the overburden strata fracture and revealed fracture fractal dimension variation characteristics;⑤ Based on fracture zone form from coal seam excavation experiment in 3D mining-induced stress conditions, set up the 3D numerical simulation model and used COMSOL Multiphysics software to carry out numerical simulation and revealed the gas migration characteristics.