Analysis of steep mining and benefit based on seasonal difference of rock and soil strength

For making full use of seasonal difference of rock and soil strength of open-pit coal mine slope, improving the angle of end-slope during mining in winter and increasing the extraction amount of coal, based on the strength theory of seasonally frozen soil and the direct shear experiment under the action of freeze-thaw, using the Geo-Slope stability analysis software, combined with physical and mechanical parameters of slope strata in winter and summer, on the basis of meeting the stability coefficient of end-slope required by regulations, this paper calculates the maximum safety angle in winter and summer as well as the enhancing range of end-slope stability coefficient in winter. The results show that: with the same angle of slope, Fs increases from summer to winter, and the average enhancing range of stability coefficient at different angles is 7.34%. Seasonal steep mining is able to increase the angle of end-slope from 39° in summer to 41° in winter. Based on steep mining under the seasonal difference of rock and soil strength, increase coal recovery of end-slope by 81 100 t and economic benefit by 6.540 5 million yuan; the safety of the end wall in the transition period can be guaranteed by increasing the amount of earth of the inner pressure displacement wall by 3 600 m3.