连续开挖诱导断层活化顶板突水机制的模拟分析

以中关铁矿采动断层突水为例,对连续开挖过程断层活化顶板突水进行有限元模拟,从力学角度研究断层带应力和损伤区迁移过程,分析断层活化机制.研究表明:连续开挖是造成断层损伤区产生、累积扩展到贯通的主要诱因;随着开挖推进断层带内剪应力集中区域沿断层从上到下逐渐向顶板转移,断层损伤区状态由压剪变为拉剪,并不断扩展;损伤区在断层揭露时完全贯通,形成导水通道并诱发突水灾害.因此,对于工作面前方的非导水断层,采用水平超前钻孔未必能查明断层活化导水情况,为确保安全,需补充斜向上钻孔,探查更高位置断层的导水性.

Numerical Simulation on the Mechanism of Fault Reactivation Induced Water Inrush Associated with the Excavating Process

A case of water inrush through fault induced by mining in Zhongguan iron mine was studied by the finite element simulation. The fault stress and damage zones were analyzed to study the mechanism of fault reactivation-induced water inrush. The simulation results illustrate that the excavating process is the cause of damage zones initiation， accumulation， extension and coalescence. The fault shear stress concentration moves from the top downward to roof gradually. The compression-shear damage zone in the fault changes to tension-shear damage zone and grows gradually. When the fault is fully exposed， the connected damage zone provides a channel for the groundwater outburst and finally causes the inrush incident. Therefore， the conductivity of the natural waterproof fault cannot be completely confirmed by horizontal cover hole before excavations. To be safe， more acclivitous cover holes should be drilled to probe the conductivity of the fault in the higher positions for the further confirmation.