Simulation test on shaft deformation induced by mining subsidence under similar gravity field in deep soil strata

Many shafts in China have experienced large deformations in the deep soil Strata, which has had a significant impact on mining safety. This study conducted a geotechnical model test called the seepage force model to address the deformation issues of shafts caused by mining solid mineral resources in regions with deep soil strata. This test simulated the impact of mining disturbance on shaft deformation within the soil section. The simulation utilized monitoring data from the model shaft, facilitating the determination of deflection displacements across different protection areas. The findings indicated a nearly linear relationship between the maximum horizontal displacement of the shaft and the mining coal seam thickness. The shaft protection areas within the soil section were reconfigured by modifying the movement angle from 45 degrees to 37.6 degrees. Consequently, the maximum horizontal displacements of the prototype shaft decreased to 73.8, 112.7, and 170.9 mm for mining coal thicknesses of 2.7, 5.3, and 8.0 m, respectively. These values represent 26%, 24.6%, and 26.7% reductions from the original design shaft displacements. When combined with the probability integral method, the simulation test results concerning the shaft protection rock pillars were exhaustively examined. This analysis paves the way for a more logical and reliable design approach for shaft protection rock pillars in areas characterized by deep soil and thin rock strata. The study findings hold immense significance in effectively mitigating and managing mining-induced subsidence disasters and ensuring the optimal design of shaft protection zones. This paper established a seepage force test model, which realised the simulation of gravity field in a 600 m deep soil strata, to carry out experimental research on the shaft deformation induced by mining subsidence, and the simulated soil thickness is the largest. The test adopts strain gauge and distributed optical fibre sensing test method to measure the strain data at different depths of the shaft, with advanced monitoring means and high accuracy of measurement data. The findings of this research contribute to a more scientific and reliable design method for the shaft protection areas in the deep soil strata, which addresses the limitations of using measured movement angles in the design of shaft protection rock pillars.