Research on the comprehensive control technology of anchor- shotcreting- grouting for soft rock roadway: A case study

Abstract

Effective and safe support in soft rock roadways remains a critical challenge in underground coal mining due to the rocks' extreme weakness and susceptibility to weathering and water invasion. In this paper, the tailgate of the longwall panel 2606, a typical soft rock roadway, excavated along the edges of mined-out areas with thin pillars of Lvtang Coal Mine in Guizhou, China is taken as the engineering background. Despite the use of a combination of rock bolts, cable bolts, and surface support systems, significant roadway deformation was observed. The mechanisms behind the significant deformation were analyzed through in-situ tests and clay mineral composition analysis. The analyses revealed that the primary causes of the roadway's large deformation were the low strength and susceptibility to weathering of the coal and surrounding rock. A novel synergistic control strategy combining anchor, shotcreting and grouting was proposed for supporting soft rock roadways. Detailed numerical simulations were conducted to evaluate the deformation and stability of the tailgate under various support scenarios, validating the effectiveness of the proposed support scheme. The synergistic support strategy was implemented to reinforce the 2606 tailgate, and field monitoring was conducted to assess its effectiveness. Monitoring data indicated that the rib deformation with the new support design was reduced by 66% compared to the original design. The results demonstrated that the improved synergistic support system effectively eliminated large deformations and maintained the stability of the tailgate. These findings provide a valuable engineering reference for supporting and reinforcing soft rock roadways under similar geological conditions.