采动影响下陷落柱的滞后突水机理研究

Study on the mechanism of delayed water inrush of collapse column under the influence of mining

为了研究陷落柱突水的滞后和突发特性,基于采动前后陷落柱的应力变化规律,通过自行设计的破碎岩体渗流试验系统进行陷落柱的破碎岩体渗透性试验,分析了应力集中状态下轴压对破碎岩体渗流特性的影响规律,阐述了破碎岩体二次破坏后的分维度变化规律及其对渗流的影响,研究了采动影响下陷落柱渗透率和启动压力梯度的变化规律.研究结果表明:在采动影响下,陷落柱经历原岩应力-应力集中-应力释放的变化过程,在此过程中其渗透率先减小后增大,而启动压力梯度先增大后减小;陷落柱突水的滞后性是由于采动影响下破碎岩体的压实作用、二次破坏造成的渗透率减小和颗粒运移形成的渗流衰减等因素共同引起的.

In order to investigate the hysteresis and burstiness of water-inrush from collapse column, based on the stress variation rules of collapse column before and after mining, the per- meability test of the broken rock mass was conducted through self-designed broken rock mass seepage test system. The influence of axial compression on the broken rock mass seepage char- acteristics in stress concentration condition was analyzed. The fractional dimension change rule after secondary breaking of the broken rock mass and its influence on seepage was elaborated. The change rules of collapse column permeability and starting pressure gradient under the in- fluence of mining were studied. The results show that under the influence of mining, the col- lapse column goes through a change process of original rock stress-stress concentration-stress release. In this change process, the permeability decreases first and then increases whereas starting pressure gradient increases first and then decreases. The hysteresis of collapse column water-inrush is a combined result of the compaction of broken rock mass, the decrease of per- meability after the secondary breaking, and seepage attenuation caused by particle migration under the influence of mining.