Study on anchor grouting reinforcement support control method for deep large section chambers

Addressing the engineering challenge of controlling surrounding rock stability in large-section chambers under deep mining conditions, this study investigates the failure mechanism of conventional bolt-mesh-cable-shotcrete support and the reinforcement mechanism of bolt-grouting combined support, using the −950 m level belt head chambers in Wanfu Coal Mine as the engineering case. A three-dimensional finite difference numerical model was established to comparatively analyze the response characteristics of the surrounding rock under three scenarios: unsupported, conventionally supported with bolt-mesh-cable-shotcrete, and supported with the novel bolt-grouting system. Quantitative results demonstrate that, compared to the unsupported scenario, the bolt-mesh-cable-shotcrete support reduces the extent of the plastic zone in the ribs, roof, and floor by 31.1%, 40.0%, and 37.3%, respectively. The bolt-grouting support system further significantly suppresses plastic zone development, achieving reductions of 68.9%, 73.3%, and 78.4% for the ribs, roof, and floor, respectively. Moreover, optimization of the support-induced stress field reduces the axial force in the anchor cables and anchor rods by 15.9% and 9.2%, respectively. Based on field monitoring data and theoretical analysis, design parameters for bolt-grouting collaborative support suitable for deep high-stress environments are proposed, providing a theoretical basis and technical guidance for deep roadway support design.