Overburden fracture evolution and pressure relief gas extraction in superimposed coal seam group mining
Aiming at the gas overrun at the upper-corner of working face caused by poor extraction effect of pressure relief gas in mining fracture zone,we take the 11210 face of Zhaojiazhai Coal Mine as the engineering background,to study the evolution characteristics of mining fracture induced by superimposed coal seam group mining on overlying strata,and determine the optimal horizon of gas extraction through field verification.The results show that:during the coal seam group superposition mining,the stress is highly concentrated outside the pressure relief area,and within the pressure relief protection range,the stress concentration phenomenon is insignificant,and the peak stress is smaller than the in-situ stress of the II1 coal seam;the superposition mining causes the superposition pressure relief of the overburden,which leads to superpositional changes of the displacement field of the overburden,and the maximum subsidence of the rock layers further increases.After the mining,the rock layer in the middle of the overburden in the mining area is compacted,and the rock layer fissures at both ends are more developed,forming a certain range of fissure development area.Reasonable layer selection for drilling holes in the rift zone is determined through field tests,and the results of physical similarity simulation are verified through on-site monitoring of the drilling holes.
coal seam group miningoverburden fissuresimilar simulationlong directional drill holes
万方数据
维普
