Water-induced damage mechanism and dual-radius grouting control of weakly cemented argillaceous roadways in Western China

The weakly cemented argillaceous surrounding rock (WSR) presents significant challenges in underground roadways in Western China, characterized by water-induced softening, large deformations, and difficult stability control. This study systematically investigates the mechanism of water-induced deterioration and the corresponding control technology for roadways with WSR through laboratory experiments, numerical simulations, and field monitoring. Experimental results highlight the critical role of moisture content and confining pressure in dictating the strength and deformation response of WSR. UDEC Trigon simulations elucidate the evolution of fracture propagation and plastic zones under hydro-mechanical coupling, showing that the total damage degree in the roof increases dramatically from 48% to 97% as the water content rises from 2% to 12%, with a transition from a symmetrical to an asymmetrical failure pattern. To address this, a control technology using combined deep and shallow grouting reinforcement is proposed. COMSOL-based simulations optimize the grouting parameters, determining that the optimal grouting pressure is 1-2 MPa for shallow holes and 3-4 MPa for deep holes, with injection times of 6-8 min yielding diffusion radii of 1.5-2.0 m and 2.5-3.0 m, respectively. Field applications at the tailgate of panel 1801 in Dananhu No. 5 Mine confirm that this method successfully mitigates roadway deformation and secures prolonged stability. The findings provide both theoretical insights and a practical methodology for supporting roadways with WSR under challenging hydrogeological conditions.