Grouting reinforcement mechanisms and their significance in controlling surrounding rock deformation of tunnels passing through fault zones

The stability of tunnel surrounding rock in deep-mine fault fracture zones is poor, significantly affecting safe and efficient mining operations. Thus, exploring the deformation and failure mechanisms of tunnel surrounding rock and researching reinforcement measures for tunnels passing through fault zones are important. This study analyzed rock specimens' deformation and failure mechanisms with varying joint angles and penetration rates. Subsequently, it investigated the strengthening effects of different joint-filling materials on the mechanical properties of jointed rock specimens and their impacts on failure modes. Through numerical simulation, a rock-mass model with a fault fracture zone was constructed to explore the diffusion law of grouting slurry in tunnel surrounding rock and evaluate the grouting reinforcement effect. Additionally, grouting reinforcement and water-blocking measures for the surrounding rock of tunnels in deep-mining fault-fracture-zone areas were studied. The main innovative contributions of this study are as follows: the coupled effects of joint dip angle, penetration rate, and filling material type on the strength and failure modes of jointed rock specimens were systematically revealed, clarifying the control mechanism of filling-body bond performance on crack propagation paths at joint tips; a grouting diffusion–stress coupling model for fault fracture zones was established by introducing the time-dependent viscosity of Bingham fluid into the modified Darcy's law, quantifying the spatiotemporal evolution of slurry density at different distances from grouting holes; a field-scale "water-release-then-grouting" sequential treatment technology was proposed for high-pressure and high-flow water-inrush channels in the Sanshandao Gold Mine, and the optimization suggestions for grouting parameters were verified by field applications. The research findings offer theoretical and technical guidance for preventing and controlling rock instability and water-seepage inflow in surrounding rock.