Mining-induced stress field prediction model based on the"slab-beam"structure of overburden key strata
Scientific and accurate prediction of the spatial evolutions of the mining-induced stress field is of great significance for the pre-warning and prevention of dynamic disasters.However,existing predic-tion methods,which fail to sufficiently consider the occurrence conditions and the fracture movement characteristics of overburden key strata,are not suitable for the mining conditions where the overburden encompasses a typical thick and hard key stratum or multiple key strata.By simplifying key strata in the bending subsidence zone into multi-layer laminated infinite elastic foundation slabs,those in the fracture zone on the coal mass side into semi-infinite elastic foundation slabs,and those in fracture zone on the goaf side into multi-layer laminated masonry beams,a mining stress field prediction model based on the"slab-beam"structure of overburden key strata was established.Meanwhile,a method of predicting the two-dimensional distribution of mining-induced stress and stope abutment pressure of key strata at differ-ent horizons was proposed and verified using the measurement results of mining-induced stress and mine pressure behaviors in Tingnan Coal Mine and Haizi Coal Mine.Furthermore,how the goaf length and the key stratum thickness influence the mining stress field was revealed,and the mechanical mechanism and control effect of grouting filling on the serious concentration of mining-induced stress under thick and hard key strata were illustrated.It is found that the key stratum of 120-meter-thick igneous rock in the Ⅱ 1024 working face of Haizi Coal Mine merely transfers 35.1％of its load to the goaf center,which results in serious concentration of stope abutment pressure.The grouting filling technology can in-crease this proportion to 93.9％,reduce the peak stress concentration coefficient of abutment pressure from 1.90 to 1.17,and narrow the influence range from 309 m to 138 m,hence ensuring safe mining in the working face.
key stratamining stress fieldabutment pressurecoal and gas outburstgrouting filling
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