Effect of combined mining with steeply dipping seam on stability of surrounding rock of inclined shaft in weakly cemented stratum

The combined mining with steeply dipping seam in weakly cemented stratum causes the original stress in the upper strata to be nonlinearly superimposed on the mining disturbance stress. Although the surrounding rock of the main inclined shaft is outside the designed " displacement angle ", with the extension of the depth of the wellbore and the increase of the volume of the mining, the regional deformation still has an important impact on the stability of the surrounding rock of the wellbore. In view of this, this study established a three-dimensional geological model of the mining area and numerically analyzed the influence of the combined mining of No. 3 coal and No. 9 coal with steeply dipping seam on the surrounding rock stress and deformation of the main inclined shaft. The research shows that the No. 3 coal mining has little influence on the surrounding rock of the main inclined shaft. The distribution of the stress distribution in the main inclined shaft after the No. 3 coal and No. 9 coal mining is redistributed. The stratum stress of the stratum elevation +800 similar to+900m is significantly affected by the mining disturbance, but it has little effect on the stress distribution of the surrounding rock of the main inclined shaft arching stage strata. No. 3 coal seam mining and No. 9 coal seam mining have a greater impact on the position of the main inclined shaft surrounding rock elevation of +950 m, but the overall settlement is still small (maximum 8 mm). Therefore, the influence of underground combined mining disturbance has little effect on the arching stage strata of the main inclined shaft, and the surrounding rock of the main inclined shaft arching stage strata is safe and stable.