结合祁东煤矿松散承压含水层下采煤压架突水灾害防治问题,开展松散承压含水层水位变化与顶板来压联动效应的实测与实验研究。结果表明:松散承压含水层水位下降超前于工作面压架突水,且水位下降速度基本保持不变。水位下降幅度和下降速度与工作面来压强烈程度密切相关,水位下降幅度和下降速度越大,工作面来压越强烈,压架突水危险性越大。覆岩关键层的不同破断运动形态是导致水位变化与顶板来压存在上述联动效应的主要原因。当关键层逐层破断时,覆岩缓慢回转下沉,水位降幅和降速较小,不会发生压架突水灾害;而当关键层复合破断时,关键层结构易产生滑落失稳,短时间内大量采空体积传至基岩顶界面,水位出现大幅度快速下降,存在压架突水危险性。利用松散承压含水层水位变化与顶板来压的联动效应,提出将水位下降速度作为预警指标对压架突水灾害进行预警的方法,并基于地下水动力学原理导出工作面压架突水时的水位降速临界预警值计算公式,指导祁东煤矿6130工作面压架突水灾害防治实践。
According to the disaster prevention problem of support crushing and water inrush when mining underlying unconsolidated confined aquifer in Qidong coal mine,the actual measurement and experimental study of connected effect between water level variation and roof weighting of working face are conducted.The study results show as follows:water level drawdown appears before support crushing and water inrush;and the velocity of water level drawdown basically keeps constant.The scope and speed of water level drawdown are closely related to the intensity of the roof weighting of working face.The greater the scope and speed of water level drawdown are,more intense the weighting pressure is;thus the danger of support crushing and water inrush increases.Different modalities of overburden stratum breaking movements are the main reason for the above connected effect.When the key stratum breaks one by one,the overburden strata rotates and descends slowly;and the scope and speed of water level drawdown are smaller.There is no danger of support crushing and water inrush accident.When compound breakage of key stratum happens,the overburden strata slide unstably and collapse holistically;and large numbers of volumes of caving spaces transfer to the top surface of bedrock in a short time.Meanwhile,the water level descends greatly and quickly,in which case the danger of support crushing and water inrush accident exists.Using the connected effect between water level variation of unconsolidated confined aquifer and roof weighting of working face,the warning method using drawdown speed of groundwater level for support crashing and water inrush accidents when mining underlying unconsolidated confined aquifer is put forward.Based on the theory of groundwater dynamics,the calculation formula for critical warming values of drawdown speed of water level are given when support crushing and water inrush accident happen at the working face.The calculation formula are served as guidance for the support crushing and water inrush prevention pra