深部厚硬顶板综放开采覆岩运移三维物理模拟试验研究

为分析深部厚硬顶板破断对厚煤层安全开采的影响,根据胡家河矿402102工作面工程地质和开采条件,构建了大型真三维相似物理模拟试验(3500 mm×3000 mm×2000 mm),开展了留煤柱双工作面开采的试验研究。利用光栅位移连续监测装置对采动覆岩位移进行实时监测,获得了厚硬顶板条件下厚煤层开采覆岩破断运移规律和"三带"动态演化特征。研究结果表明:厚硬关键层变形破断时,软弱岩层会发生协同运动,位移监测点位移量发生突增,监测点位移曲线随工作面推进呈"台阶式"变化。在一侧临空条件下,402102工作面亚关键层1(粉砂岩)初次破断步距为43 m,周期破断步距为21 m;亚关键层2(含砾粗砂岩)初次破断步距为74 m,周期破断步距为51 m;亚关键层3(中砂岩)初次破断步距为171 m。当亚关键层2发生周期性破断和亚关键层3发生初次破断时,采空区位移监测点位移量均发生增幅,覆岩发生大范围整体性运动,矿压显现较为剧烈;受402103采空区采动覆岩结构的影响,在402102工作面回采时,其回风巷侧覆岩运移较为剧烈,巷道受动压影响较大。根据位移监测点的位移量和覆岩变形碎胀因子max(Ki)的大小,对采动覆岩"三带"发育形态进行了初步判别,亚关键层1(粉砂岩)和亚关键层2(含砾粗砂岩)均处于冒落带中,且随着工作面推进,冒落带和裂隙带高度呈"台阶式"增大。

Three-dimensional physical simulation of overburden migration in deep thick hard roof fully-mechanized caving mining

In order to analyze the influences of breaking of deep thick hard roofs on the safe mining of thick coal seam,a large three-dimensional physical simulation experiment(3500 mm×3000 mm×2000 mm)is constructed,and the experimental study on the double-working face mining with coal pillar is carried out according to the engineering geology and mining conditions of coal face 402102 of Hujiahe Coal Mine.The grating displacement continuous monitoring device is used to monitor the displacement of overburden in real time,and the fracture migration laws and the dynamic evolution characteristics of"three zones"of overburden in thick coal seam mining under thick hard roofs are obtained.The results show that:when the thick and hard key stratum is deformed and broken,the weak rock stratum will move in coordination,the displacement at the monitoring point will increase sharply,and the displacement curve will be pushed forward in a"stepped"way with the advancing of working face.When one side of the working face is mined out,the first weighting interval of SKS1(siltstone)of working face 402102 is 43 m,and the periodic weighting interval is 21 m.The first weighting interval of SKS2(coarse sandstone)is 73 m,and the periodic weighting interval is 51 m.The first weighting interval of SKS3(medium sandstone)is 171 m.When SKS2 breaks periodically and SKS3 breaks for the first time,the overburden rocks move in a wide range and the ground pressure is intense.Under the influences of mining-induced overburden structure in goaf 402103,the overlying rocks of the return airway on the working face 402102 migrate violently,and the roadway is greatly affected by dynamic pressure.According to the displacement at the monitoring points and the size of overburden deformation and fragmentation expansion factor max(Ki),the development morphology of the"three zones"is identified.Both SKS1 and SKS2 are in the caving zone,and the heights of the caving zone and fracture zone increase in a"stepped"manner with the advancing of the working face.