Stress and load-bearing structure analysis of the surrounding rock in a soft broken roadway

Abstract

After roadway excavation, the surrounding rock is the main bearing structure for the original stress and forms a supporting ring with the supporting structure. The automatic load-bearing ring is the main interactional structure between the surrounding rock and the supporting system. The rock mass strength, stress, and deformation characteristics were considered to establish the theoretical calculation model for the softened broken surrounding rocks. In the model, the strength, stress, and deformations were analyzed for the elastic-plastic softening and broken zones. The analytical solution was obtained for the stress field, displacement field, and plastic damage range of the surrounding rocks. Considering the postpeak strength softening, shearing dilatation effects, original rock stress, and supporting resistance, the roadway bearing structure was divided into a shallow bearing layer and a deep bearing layer. Moreover, the crucial bearing layer was vital to the bearing capacity and stability of the layer. The influence of the shallow bearing layer, deep bearing layer, and crucial bearing layer on controlling the deformation of the surrounding rock was also analyzed. Based on the evolution characteristics of the shallow and deep buried surrounding rock, the weaker the residual strength of the surrounding rock was, the thicker the shallow and deep buried surrounding rock; the thicker the shallow and deep buried layers were, the greater the surface displacement of the surrounding rock; the crucial bearing layer was farther away from the roadway, and the roadway surface displacement was great; the greater the supporting resistance was, the thinner the shallow and deep bearing layers; and the crucial bearing layer was closer to the roadway, and the roadway deformation control was effective. Furthermore, based on the specific calculation example, the influence of the residual stress and supporting measures on the evolution characteristics of shallow and deep layers and roadway deformation was analyzed in detail.