煤矿隐伏断层递进导升突水的临界判据及物理模拟研究

为解决煤层底板隐伏断层突水的难题,以递进导升及断裂力学原理为基础,建立了断层递进导升简化断裂力学模型,推导了递进导升突水临界力学解析式和断层到底板破坏区的最小安全距离,然后利用相似材料模拟实验研究底板隐伏断层递进导升过程。实验结果表明:底板隐伏断层在采动影响下,尖端的应力发生了集中,应力强度因子增加,当其超过临界值时,即发生扩展,导升高度增加,随机应力得以释放;随着工作面的推进,应力再次集中,强度因子再次增加,当其再次达到临界值时,导升高度再次升高,达到底板破坏区的最小安全距离发生突水,递进导升突水强度随初始导水高度的增加而增加、随岩层强度降低而增强。隐伏断层初始发育自然导升高度越大,其递进导升破坏越强烈,导致沟通煤层底板更易发生突水现象。

Critical criterion and physical simulation research on progressive ascending water inrush in hidden faults of coal mines

In order to solve the problem of concealed hidden fault water inrush in the coal floor,the simplified fracture mechanical principle model of buried fault progressive ascending was established in this study.The critical mechanical analytical formula was deduced and the minimum safe distance between fault and damage area of footwall was calculated.Experiments were conducted to simulate the process of buried fault progressive ascending by employing the similar material.There was stress concentration in the tip of buried fault under the mining effect.The stress intensity factor increased beyond the critical value,consequently,the expansion happened,which led to lift height increase and released random stress.With the face advancing,the stress concentrated,the intensity factor increased and exceeded a critical value once again.Water inrush would occur when the lift height increased and reached the minimum distance of footwall destruction area.The intensity of water inrush increased with the increase of the initial water conduction height and the decrease of the rock strength.If the natural initial lift height of blind fault was higher,the progressive lift destruction would be stronger,which would easily lead to the water inrush in the footwall of coal seams.