Breaking dynamic load mechanism and application of high key strata in gully area of shallow coal seam
This study is aimed at tackling problems induced by dynamic loads on coal rock in western gully areas through multiple research methods including similar simulation,theoretical calculation analy-sis,and field measurement.Specifically,the characteristics of intense mining pressure on the working face across the gully area under composite key strata were comparatively analyzed.On this basis,a structural instability model of the uphill section in a gully area under composite key strata was construc-ted,and the calculation formulas of the rotation deformation of high key strata and the initial fracture step of sliding instability during the movement of overburden were derived.The research results indicate that when the working face passes through the uphill section of high key strata in a gully area,severe dy-namic loading phenomena such as roof cutting,support crushing,and step sinking are likely to occur.Initially,rotation deformation instability occurs in the uphill section of the gully area,followed by the sliding of chain structure formed by broken blocks,which further affects the lower working face and ulti-mately results in intense mining pressure.By constructing the basic unit of the structural mechanical mod-el of the non-uniform load beam at high key strata in the continuous gully area,the step distances for ini-tial rotation deformation and sliding instability were calculated to be 27 m and 142 m,respectively,which is consistent with the actual support crushing accident that occurred at 145 m away from the bot-tom of the first gully when the 1305-2 working face passed there.Subsequently,combined with the fail-ure mechanism of high key strata under dynamic loads,comprehensive prevention and control measures for mining pressure in valley terrains under dynamic loads were proposed and applied to Zhujiamao Coal Mine.According to the calculation results,severe mining pressure is likely to appear in the 1305-2 and 1307-2 working faces at distances of 147 m(when it passes the second value)and 126 m,respectively.Hydraulic fracturing and other prevention and control measures were carried out in these calculated haz-ardous areas,and the effect turned to be excellent.This study provides a theoretical basis for the preven-tion and control of dynamic load mining pressure in valley terrains.
shallow coal seamgully valley areasliding instabilitydynamic load mining pressureprevention measures
万方数据
维普
