Elastic-Plastic Analysis of Surrounding Rock in Deep Roadway Considering Shear Dilatancy Property under Non-Uniform Stress Field

Abstract

The surrounding rock of deep engineering roadway is under the complicated mechanical environment of non-uniform stress distribution, and the stress mechanical model of uniform distribution is obviously different from the surrounding rock of roadway in real stress state. Thus, accurately evaluating the stress and deformation state of surrounding rock is infeasible in non-uniform stress field when employing the mechanical model developed for uniform stress conditions. To reflect the real mechanical state of the roadway surrounding rock accurately and calculate the radius of the plastic zone in roadway surrounding rock precisely, a mechanical model of roadway surrounding rock under non-uniform stress conditions was established in this study based on unified strength theory. One floor roadway of 1231 (1) working face in Panyi coal mine of Huainan coal field was considered as an example. The influences of side pressure coefficient and intermediate principal stress on the scope of the plastic zone in surrounding rock were analyzed. The effect of shear dilatancy property on the deformation and failure process of surrounding rock was discussed, and the field monitoring and verification of the scope of the plastic zone in surrounding rock were conducted on the floor roadways of 1231 (1) and 1252 (1) working face in this mine. Research results indicate that the displacement of the plastic zone enlarges by nearly thrice while the side pressure coefficient increases, and the radius of the plastic zone in roadway surrounding rock in the vertical direction is obviously larger than that in the horizontal direction, which reflects an anisotropic characteristic of the surrounding rock of deep roadway. The displacement of the plastic zone in the surrounding rock enlarges by at least 60% while the shear dilatancy parameter increases, but the morphological change of the plastic zone is minor. Furthermore, the displacement of the plastic zone in the surrounding rock reduces by nearly 35% while the intermediate principal stress increases. Field test results of the scope of the plastic zone in roadway surrounding rock through borehole peering under different side pressure coefficients match well with the results from theoretical calculation, which verifies the applicability and accuracy of the mechanical model of roadway surrounding rock established in this study. The research results can provide theoretical references for stability analysis and support the design of the surrounding rock of deep roadway.

Distribution Law of Principal Stress Difference of Deep Surrounding Rock of Gob-side Entry and Optimum Design of Coal Pillar Width

“…In addition, existing research on the distribution of mining stress field focuses on the distribution of abutment pressure, which indicates the change in the vertical stress of surrounding rock. However, the failure of surrounding rock in the stress field environment, where deep roadway is located, is mostly compression-shear failure, which generally conforms to the MC criterion (the maximum shear stress failure criterion) [26]. The principal stress difference of surrounding rock in the stress state determines the occurrence of failure [27][28].…”