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为了对水体下急斜煤层的安全回采提供依据,基于龙湖煤矿南二采区急斜煤层的水文工程地质和煤岩层赋存条件,采用离散元UDEC2D数值计算,分析了覆岩关键层对急斜煤层开采导水裂隙分布和防水煤柱稳定性的影响,结果表明:当上覆岩层无关键层时,急斜煤层开采导水裂隙呈“耳型”分布,而当上覆岩层存在关键层时,导水裂隙以平行于岩层层面的离层裂隙为主,且随着煤层采厚的增加呈抛物线型增大趋势,顶板初次破断后导水裂隙向关键层及其上方岩层发育;急斜煤层覆岩关键层的存在,将明显增大防水煤柱的抽冒范围,水体更易沿防水煤柱塑性破坏区渗流进入工作面采空区。据此,现场设计了分带仰斜充填开采方法,并采取了加固防水煤柱的措施,有效确保了水体下急斜煤层的安全回采。
In order to provide basis for safe recovery of steep coal seam under water, based on the hydrogeology and geology of steep coal seam and the occurrence conditions of coal seam in South Second Mining Area of Longhu Coal Mine, discrete element UDEC2D numerical calculation was used to analyze the effect of critical strata on steep slope The results show that when the overlying strata have no key strata, the water-bearing fractures in the mining of steep coal seam show a “ear type ” distribution, and when the overlying strata is the key The water-bearing fissures are dominated by the fissures parallel to the rock strata and increase parabolically with the thickening of the coal seam. The water-bearing fissures are developed to the key strata and the rock strata above it after the initial fracture of the roof The existence of the key strata in the overburden coal seam will obviously increase the pumping range of the water-proof coal pillar, and the water seepage is more likely to flow into the goaf in the coal face along the plastic failure zone of the water-proof coal pillar. Accordingly, on the spot, the design of the method of striping and backfilling was designed and the measures of strengthening the waterproof coal pillar were taken, which effectively ensured the safe recovery of the steep coal seam under the water body.