断层影响下底板隔水层的破坏机理研究

Research on the Failure Mechanism of Water-Resisting Floor Affected by Fault

为了研究断层对底板隔水层稳定性的影响,根据岩石剪切破坏的极限平衡条件推导出隔水层破坏的临界水压力公式,并提出突水判据.基于临界水压力公式分析了断层倾角、内聚力和断层煤柱宽度对底板隔水层破坏的影响规律.结果表明,断层倾角越小,底板隔水层能够承受的临界水压越小,底板就越容易发生突水;若断层带内聚力越小,即断层带强度越软弱,底板临界水压力也随之减小,此时底板发生突水的可能性越大;断层煤柱留设宽度越大,底板越不容易发生突水.工程应用表明预设的煤柱宽度偏小,有发生底板突水的可能,为保证安全开采,根据所推出的临界水压力公式计算得出合理的断层煤柱宽度应为34.3 m.

According to the limit equilibrium condition of rock＇s shear failure,we deduce the formula of critical water pressure to study the effect of fault on the stability of water-resisting floor and propose the water-inrush criterion.Based on the deduced formula,we analyze the effect laws caused by the dip angle,the cohesion force of fault,and the width of fault pillar.The main results are as follows： 1） the smaller the dip angle of fault is,the lower the bearing ability of the water-resisting floor will be,thus the water-inrush of floor will happen more easily;2） the smaller the cohesion force of fault is,namely the weaker the strength of the fault is,the less the critical water pressure of the floor will be,and the greater the probability of the water-inrush becomes;and 3） the larger the fault pillar is,the more difficultly the water-inrush will happen.The engineering application shows that the reserved fault pillar is small,so it is quite possible to have the water-inrush.For the safety mining,the reasonable width of fault pillar should be 34.3 m according to the calculation with the deduced formula.