采动裂隙网络实时演化及连通性特征

以平顶山煤业集团八矿己15-14120采煤工作面为试验基地，借助改进后的本质安全型钻孔裂隙窥视仪，实时采集采煤工作面前方煤岩体裂隙网络随工作面推进的演化过程。结合分形几何理论与裂隙岩体连通率投影算法，揭示了采动影响下，工作面前方裂隙网络演化分形特征及连通率变化规律。结果表明：采动对平煤八矿己15-14120采煤工作面上覆岩层裂隙网络沿开采方向的影响范围约为50 m；随着工作面不断接近试验测点，煤岩体采动裂隙网络分形维数总体呈上升趋势，并与矿压分布有较好的对应关系；同时，煤岩体连通率随采煤工作面推进上升趋势明显，可依次分为线性缓慢增长阶段、指数增长阶段及平稳阶段。

Real-time evolution and connectivity of mined crack network

Based on the field conditions of coal mining face No.15-14120 at No.8 Mine of Pingdingshan Coal Mining Group，the information for real time evolution of coal rock crack network with advancement of working face was collected by using improved intrinsically safe borehole video instrument.Fractal theory and projective arithmetic for the two dimensional connectivity of cracked rock mass were employed to characterize the evolution of crack network and variation of connectivity caused by mining.The results show that the influenced domain of crack network ahead of the working face is 50 m approximately in the condition of coal mining face No.15-14120 at No.8 Mine of Pingdingshan Coal Mining Group，and the calculated fractal dimension of crack network increases as the distance between the monitoring hole and the mining face decreases，which exhibites a good agreement with the variation of pressure at overburden strata.Moreover，the calculated connectivity of mining induced crack network increases obviously with the advancing of mining face and the increasing process can be divided into linear phase，exponential phase and constant phase.