Research on the surrounding rock failure mechanism and collaborative control technology for a large-span open cut in a deep-buried working face

A large-span open cut located at a depth of nearly 1,000 m in the 6317 working face of Shandong Tangkou Coal Industry Co., Ltd. was selected as the engineering background, and a mechanical model was established to investigate the surrounding rock failure mechanism of the open cut. Based on range analysis, the principal factors governing the plastic failure of the surrounding rock and their sensitivity were identified. Subsequently, FLAC^3D numerical simulation software was employed to investigate the deformation and failure characteristics of the surrounding rock. On this basis, an active-passive collaborative support scheme consisting of rock bolts, wire mesh, cable bolts, and unit supports was proposed. The support equipment and materials were explicitly incorporated into the numerical model to simulate and evaluate the effectiveness of the proposed control scheme. The results of the field-scale industrial test demonstrated that the active-passive collaborative support scheme effectively controlled the deformation of the surrounding rock. The maximum roof subsidence, floor heave, left-rib convergence, and right-rib convergence were limited to 102, 50, 79 and 84 mm, respectively. Moreover, the maximum cumulative subsidence values measured at the shallow and deep reference points were only 64 and 31 mm, respectively.