Partition Height Limit Shallow Seam Mining Research Under The River

Strata movement and fracture of surrounding rock after coal excavation would causewater submerging whole colliery when broken strata were exposed to underground or surfacewater. Also decrease of water level and dry-out of river and reservoir would appear. It wasnecessary to get better understandings of mechanism of strata fracture, particularly height anddistribution of flowing fracture zone after excavation, which should be prerequisite foroptimization of valid excavation boundaries for safe excavation.We taking N24mining area mining under the river of Furong mining area ShanmushuCoal Mine as the study area through the analysis of Shanmushu Coal Mine N24mining areaof geological and mining conditions in mining, overlying strata structure and lithologiccharacter, basic physical and mechanical properties of aquifer and aquifuge, use the similarmaterial simulation and FLAC3D to study the overlying strata and ground movement anddamage law in inclined seam mining process. The experimental results show that there is alarge amount of horizontal movement and subsidence in the middle of the slope located onboth sides of the channel,subsidence basin is asymmetrical and the center of the basin movesto the downhill,there is the smaller subsidence in the valley bottom because the mountainslocated in the both sides of the river squeeze the valley botton,with the subsidence coefficientη=0.545;The uphill slopes occur bedding slip and a large amount of horizontal movement,themaximum horizontal movement factor bmax=0.4,the deviation of inflection point d上=37m ismore than30%mining depth,but the d下=21m in the downhill is only16%mining depth;Aftermining the caving zone height is28m,the height of water flowing fractured zone is more than67m,the surface slop position may occur landsilde.According to the special conditions offir ore rock without aquiclude,using F-RFPA2D simulation software, seepage law to give thewater flowing fractured zone distribution after mining and seepage law of river water inthe overlying rock fissure,the max height of water flowing fractrured zone is106m,the ratioof the height of the fractured zone to the mining height is35.Based on experimentalresults, combining with the high limit of coordinated mining method, analysis of safety coal mining scheme, and the production test.Test results show that: the high limit coordinationmining can effectively reduce the height of water flowing fractured zone and the damagedegree of surface movement and deformation, applying to the safety mining under water, andit is safe, effective way ofeconomic exploitation.