Objective and Method This study aims to investigate the relationship between the stress environment and the deformation and failure responses of surrounding rocks, thereby unraveling the inherent mechanisms underlying the deformation and failure. With cement, river sands, and gypsum as raw materials, rectangular roadway model specimens measuring 200 mm × 200 mm × 200 mm were prepared. Using a large-scale true triaxial seepage coupling testing machine, this study conducted triaxial loading tests on the rectangular roadway specimens under different lateral pressure coefficients. Using microcameras and an acoustic emission system, it monitored the whole process of the macroscopic deformation and failure, along with the evolutionary characteristics of internal damage, of the surrounding rocks of the rectangular roadway specimens. In combination with the PFC^3D numerical simulation, the distribution patterns of microcracks within the rectangular roadway specimens were determined.

Results and Conclusions During the deformation and failure of the roadway surrounding rocks under stress loading, the failure of the sides of the rectangular roadways was primarily caused by tangential stress concentration. Under continuous stress loading, the maximum bending moment was prone to occur in the middle parts of the roadway sides, resulting in tensile failure of roadways, characterized by the scaling of arc-shaped thick sheets (thick in the middle and thin at both ends). The scaling failure expanded gradually inward and formed a macroscopic V-shaped failure groove, showing pronounced layered failure characteristics. With a gradual increase in the axial load, the thickness of fragments generated by layered scaling failure decreased progressively. Concurrently, the arc-shaped thick sheets transitioned into arc-shaped thin sheets and partially scaled arc-shaped thin sheets, while the cumulative acoustic emission energy shifted from a gentle growth to stepped and then steep increases. The development of microcracks in the roadway surrounding rocks was inherently related to the stress environment. The increase in the lateral pressure coefficient inhibited the development of microcracks within the roadway surrounding rocks, with the proportion of tensile microcracks decreasing from 80.424 1% to 76.637 9%. During failure, the internal microcracks exhibited a butterfly distribution pattern. The results of this study provide an experimental reference for the stability control of the surrounding rocks of deep mining roadways.