Pressure-relief Characteristics Of Remote Ascending Order Pressure-relief Mining With Hard-thick Strata And Application

Coal seam group B is close distance with high gassy and low permeability in Huainan mining area and in the process of downward pressure-relief pressure mining,the pressure-relief effect is poor,gas control is very difficult and mining cost is high.To explore the feasibility of coal group A in the deep mining area as protective layer remote upward pressure-relief mining coal group B,taking 11223 panel of coal seam A3 and coal seam B4 as the engineering background in Paner coal mine,by theoretical analysis,laboratory experiments,the means of similar simulation experiment and in-situ test,the evolution law of induced stress field and fracture field and pressure-relief characteristics are investigated and the dynamic effect of pressure-relief gas pouring following the breaking of key stratum is also studied.First of all,based on panel 11223 and B4 coal strata structure characteristics,the engineering geological model is constructed.Combining the rock physical and mechanical parameters and using the key strata theory to calculate the key stratum number.There are 3 key strata in second west section of the panel and 2 in first east respectively and corresponding groups of strata are grouped.Secondly,according to different roof conditions in different sections,strike and trend similar material simulation and UDEC strike numerical simulation are built respectively,evolution characteristics of mining induced stress and fracture field,pressure-relief effect and range of coal seam B4 are obtained with remote upward mining under multiple key strata.Research shows that the B4 coal pressure-relief effect is poor because of cracking up of fracture is blocked with key layer and fracture height is "jumping" development with the breakage of key strata.Then,with the analysis of field test result and pressure-relief gas extraction data,stress evolution characteristics is obtained and key strata breaking law is inversed through the variation of pressure-relief gas drainage quantity.Research shows that the main reason of low pressure-relief gas drainage rate is high horizon of key stratum 3 and its difficult breakage.Finally,based on the above research results,pressure-relief gas extraction system layout optimization design is made under remote pressure-relief mining coal seamB4 by advanced panel 11223,scheme of pressure-relief gas extraction roadway is obtained.