Deformation Characteristics and Control Mechanisms of Deep High-Stress Large-Span Roadways

Controlling the surrounding rock in soft rock roadways under deep high stress, strong rheology, and intensive mining is critical for the safety, efficiency, and economy of mine production. In this study, the mechanical properties, large deformation mechanism, and support countermeasures of surrounding rock in the high-stress roadway in the Yuwu coal mine were systematically explored through laboratory tests, numerical calculations, and field measurements. It is shown that mudstone and sandstone are mainly composed of chlorite and kaolinite, respectively. Also, mudstone features elastoplasticity and experiences argillization and swelling in water. The mechanism of surrounding rock deformation in the high-stress roadway in the Yuwu coal mine was determined. As the V-shaped shear zone in the side corner expanded to the deep under high deviatoric stress, large-scale tensile damage occurred in the shallow surrounding rock. Consequently, discontinuous stresses in deep and shallow parts induce the expansion and fracturing of the roadway. The deformation velocity and damage degree of surrounding rock rise exponentially under different stress release coefficients, so the reduced distance of the face roof under control and timely support is important for restricting the free surface. An idea of “timely and active reinforcing the side and strengthening the bottom†was proposed. This approach made the loads on all the support objects within the working range. The overall deformation of the surrounding rock was controlled within 350 mm, ensuring the long-term stability of the roadway.