Parameter design method of supporting coal pillar for highwall filling mining
Reasonable design of supporting coal pillar parameters under highwall filling mining is the premise of the popularization and application of highwall mining technology.By analyzing the stress changes of coal pillars before and after highwall filling mining,the mechanism of filling bodies improving coal pillar strength is clarified.According to the effective area theory,the load above the coal pillar is calculated,the lateral constraint force of the coal pillar based on the earth pressure formula is deduced,and the strength of the coal pillar under the filling condition is obtained by combining the empirical formula of the CIMFR coal pillar strength and the Mohr-Coulomb strength criterion.The strength of the coal pillar is obtained,and the parameter design method of the supporting coal pillar under the non-uniform load under the non-uniform load is proposed.Based on the calculation method of the parameters of the supporting coal pillar in the highwall filling mining,considering the triangular load of the end-wall filling mining,a method of filling the mining chamber in sections is proposed,and the calculation method of the filling height of different strips is given.Considering the coordination of filling link and end slope mining time,and the unreasonable situation of one-step mining,the two-step filling mining sequence and the three-step filling mining sequence are designed.Taking an open-pit mine as the engineering background,the parameters of supporting coal pillar for highwall filling mining are designed.Compared with non-filling mining,the size of a single coal pillar is reduced by 3.5 m,the resource recovery rate is increased from 33.7％to 68.4％,and the amount of filling material in a single roadway is reduced by 2 053.6 m3 under the condition of segmented filling.This study puts forward the design method of supporting coal pillar under the condition of end-wall filling ning,which is of great scientific significance to promote end-wall filling mining in open-pit coal mines.
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