Study on the influence of mining sequence and depth on slope stability of end slope in open-pit mines

The end wall mining technology has the advantages of no additional stripping, safety and stability, and no support, and has a good application prospect in the recovery of coal resources in the end wall of open pit mine. During the mining process, the rock body of the slope is subjected to the double influence of mining excavation and open pit mining, which generates complex stress changes, and there is a risk of slope deformation and destabilization. Therefore, the selection of appropriate mining methods and parameters is crucial for the slope stability of end slope coal recovery. We put forward the calculation formula of coal pillar stress under sequential mining and jumping mining, and use FLAC3D software to calculate and analyze the coal pillar stability under the two methods, and study the slope stability under different mining tunnel depths in the limit state of mining. The results show that: the theoretical coal pillar stress of mining tunnel jumping is smaller than that of sequential mining due to the wider support pressure bearing interval, and the numerical calculation shows that the overall coal pillar of jumping mining is in a stable state, and compared with sequential mining, the maximum peak compressive stress of the mining tunnel is reduced by 16.97%, and there is no obvious stress concentration area, and the amount of subsidence and bottom bulge is reduced by 34.16% and 17.63%, respectively; the depth of the mining tunnel significantly affects the slope deformation amount, deformation area and its stability, and the projected position of the slope top line overlaps with the potential slip surface of the mine end slope, and the growth rate of the slope-facing displacement, settlement and floor bulge increases significantly in this interval, and the stability of the slope decreases rapidly.