Research On The Gateway Arrangement And Controlling Technique Over The Surrounding Rocks In Coal Seams Group With Close Distance

In China, the mining of close distance coal seams is very common and miningroadways are always affected by the upper coal seam mining which leads to thedifficult of surrounding rock control in lower seam. Therefore, research on theroadways arrangement in lower seam and surrounding rock control would besignificant to safe and high-efficiency mining in close distance coal seams.Surrounding rock stability of roadways in lower seam mainly affected by thelocation and supporting methods as close distance coal seams mining. In this paper,stress distribution rule and failure law of floor rock were analyzed as close distancecoal seams mining by theoretical analysis and numerical simulation that based on thereserve condition in Sha-qu and specific situation of trial sites, the arrangement rulesof roadways in rock stress zone and distressed zone and the range of stressconcentration zone, distressed zone and rock stress zone in No.3+4coal seams wereidentified, the reasonable location of No.24208belt roadway was also identifiedaccording to reasonable size of coal pillar and the No.24208belt roadway located atthe left side of No.24208return airway within45m in rock stress zone. In coal seamswith close distance, deformation laws of the roadway surrounding rock in lower seamanalyzed by numerical simulation, mechanical model of rock beam in rectangularroadway and failure mechanism of instable dynamic roadways that caused by localoverload have established. According to the deformation laws and failure mechanismof roadway surrounding rock, an asymmetric united supporting scheme of dynamicroadways has also established that combined with single hydraulic, W shape steelband and bolt-mesh-cable support. The specifications of anchor bolt and cable couldbe confirmed by theoretical calculation and numerical simulation,22×2400mmrebar resin anchors and17.8×7000mm steel wire rope anchor ropes put to use inproof,20×2200mm rebar resin anchors put to use in two sides of roadway,inter-row spacing of anchors and anchor ropes in proof was750mm×800mm,1600mm×1600mm respectively, which in the left side of roadway was800mm×800mm and700mm×800mm in the right side and proved the theoretical, technicaland economic feasibility of the supporting project.