Characterization of brittle failure using physical model experiments under polyaxial stress conditions

Abstract

Deep soft rock roadways generally present large deformation characteristics, and a vast number of workers attempt to repair them to no avail. A true 3D model test was performed based on the engineering background of the transportation roadway of the Huafeng coal mine in China. The selected analogous materials have a significant time similarity relationship with the surrounding rock, and a similar bolt-mesh-shotcrete support structure, according to the engineering background, was applied to the roadway. The test results showed that the evolution process of the rheological deformation of the roadway is two sidewalls → floor → vault → full-section convergence of the roadway. The large deformation zones of the surrounding rock are constantly transferred from the surface to the depth, and the bearing capacity of the bolts decreases rapidly after the deformation of the anchorage zones. The mechanical characteristics of the floor determine that the lower surrounding rock always repeats the failure process of the upper rock stratum, and the floor heave does not stop. The test results revealed the full-section convergence rheological deformation laws and migration laws of the internal key deformation locations of the surrounding rock and clarified the reasons for the floor heave. The model test results are verified through field monitoring, and opportunities and suggestions for secondary support are determined. These results could provide a reference for the failure process and control technology of the same type of deep soft rock roadway.