Background The western mining areas have become China's primary coal production base. In the tens of millions of tons of mines in the west, many mines adopt inclined shaft development. Since inclined shafts traverse multiple aquifers, many mine shafts have suffered shaft lining rupture and water inrush disasters to varying degrees.
Methods To investigate the influence of groundwater seepage on the stability of the surrounding rock in inclined shafts, this study employs field investigation, theoretical analysis, and numerical simulation to examine the shaft lining stability of the main inclined shaft in the water-rich affected section of the Xiaojihan Coal Mine.
Results and Conclusions Through theoretical analysis, the development patterns of the plastic zone in the surrounding rock around the shaft under different polar angles, both before and after water-induced weakening under the combined action of support and formation water pressure, were obtained. The analysis revealed that the development of the plastic zone is approximately "butterfly-shaped". Plastic zone development is more significant within the ranges of approximately 0°~45°, 135°~225°, and 315°~0°, while it is relatively less significant within the ranges of 45°~135° and 225°~315°. Furthermore, water-induced deterioration increased the development radius of the plastic zone from 5.8 meters to 8.0 meters. A fluid-solid coupling model accounting for water-induced softening was established, elucidating the mechanism of water-induced deterioration at the shaft lining-surrounding rock interface. As the shaft lining strength weakens, the development of the plastic zone in the shaft cross-section connects with the aquifer. Water from the aquifer then further weakens the surrounding rock of the shaft, resulting in a significant increase in the plastic zone and deformation of the surrounding rock, ultimately leading to shaft lining instability. For inclined shafts penetrating aquifers, grouting treatment strategies tailored to different shaft lining strengths are proposed. Simulation of grouting effects by means of modifying the mechanical parameters and permeability coefficient of the surrounding rock within the grouting zone. Simulation results demonstrate that grouting reinforcement significantly enhances the stability of the inclined shaft lining by improving surrounding rock strength and sealing aquifer fractures. The on-site application of the grouting reinforcement and water blocking scheme proposed in this article achieves a significant reduction in wellbore water inflow.
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