Stress regulation mechanism and control technology for surrounding rock of deep-buried dynamic pressure roadways under support and pressure relief conditions

Deep-buried dynamic pressure roadways in coal mines are subject to the dual influence of high stress and strong dynamic pressure, resulting in considerable deformation failure of their surrounding rock. To address the mining pressure behavior in such roadways, this study employed a comprehensive approach combining theoretical analysis, laboratory testing, and field experiments to investigate a protective engineering project for a deep-buried south wing main roadway in western China. First, the deformation failure patterns and influencing factors of the south wing dynamic pressure roadway were explored, and a mechanical model for the fracture of thick, hard roof strata in this roadway was established. Furthermore, the stress regulation mechanism of surrounding rock support and pressure relief in the dynamic pressure roadway was elucidated, and the key technical parameters for the coupled control system and their practical application were clarified. The study shows that high in-situ stress, mining-induced stress, and inadequate support strength are the fundamental causes of uncontrollable deformation in the southern wing main roadway. The cantilever beam structure formed by the fracture of the key stratum (38.05 m of medium-coarse sandstone) disrupts the stress equilibrium of the adjacent south wing main roadway and accelerates deformation failure of the surrounding rock mass. The energy released by fracturing in hard roof strata is positively correlated with tensile strength and stratum thickness, but negatively correlated with elastic modulus. High-strength support optimizes the stress environment in the near-field surrounding rock to enhance its load-bearing capacity, while pre-fracturing for roof stress relief reduces lateral bearing pressure and its distribution range to prematurely release elastic strain energy accumulated in the hard roof. High-strength support shifts the stress Mohr circle rightward as a whole and enlarges the shear strength envelope, while pre-fracturing shifts the stress Mohr circle leftward. Their coupled effect causes the stress Mohr circle to contract inward and move away from the shear strength envelope. Based on this rock mass stress regulation mechanism, a coupled control technology scheme of "high-strength support + roof pressure relief" for deep-buried dynamic pressure roadways was proposed. Field testing demonstrates that the proposed scheme improved the stress state of the protective coal pillar, reduced the periodic weighting length and dynamic load coefficient, effectively controlled surrounding rock deformation failure, and ensured the safety and stability of the south wing main roadway. The research results can provide engineering experience and technical support for the control of surrounding rock deformation in deep-buried dynamic pressure roadways.