Elastoplastic Solutions About the Gas Drainage Hole Based on Mohr–Coulomb Yield Criterion

The distribution characteristics of stresses and displacements in the plastic region around the gas drainage hole generated by non-uniform geostresses can provide some guidance for the supporting design of the gas drainage hole and the drainage operation process. The length of gas drainage hole is usually much larger than the diameter, the surrounding coals are taken as isotropic homogeneous media, and so the elastoplastic analysis of gas drainage hole under non-uniform geostresses can be simplified as a 2-dimensional plane strain problem. The coals are supposed to agree with Mohr–Coulomb yield criterion, the stresses and displacements at the elastoplastic interface are considered as continuous, the inner side of the gas drainage hole is under the gas drainage pressure, and the theoretical solutions about the elastoplastic interface, stresses and displacements are obtained. In the end, one mine in Henan Province of P. R. China is selected as an engineering example, geostresses are in situ measured near the gas draining hole, the distribution curves of stresses and displacements in the plastic region are drawn, non-uniform coefficient is defined as the ratio of the maximum geo-stress to the minimum, and the influence of non-uniform coefficient on the stresses and displacements are analyzed.