隔水土层孔隙水压畸变与顶板突水灾变的时空响应特征模拟研究

Spatial-temporal characteristics simulation of pore water pressure in aquiclude and roof water inrush

随着采煤工作面的推进,上覆隔水土层将受到周期性动载荷作用,引起的孔隙水压畸变在覆岩中产生的力学响应对于浅埋煤层顶板突水灾变有着重要的前兆预警意义。为了分析隔水土层孔隙水压与顶板突水之间的时空响应规律,将隔水土层简化为饱和多孔固液混合介质并构建了隔水土层黏弹性动力学模型,求得孔隙水压分布解析解;应用模拟软件构建了相应的流固耦合模型,分析了在不同开采强度条件下隔水土层孔隙水压变化与覆岩破坏演变规律;基于固液耦合试验平台,进行孔隙水压监测试验,进一步揭示并验证了开采扰动及渗流作用下隔水土层孔隙水压与突水灾变之间的对应关系。研究表明:隔水土层孔隙水压与开采扰动存在紧密联系,当隔水土层孔隙水压因开采扰动而积聚至峰值后,会发生急速消散,土层隔水性消失,工作面顶板则对应发生突水灾变,之后孔隙水压在相对较低的水平短幅波动,其时空响应特征的研究对于富水区下顶板突水预警系统的建立奠定了基础。

With the advancing of working face,the overlying aquiclude is subject to periodic dynamic loading,and mechanical responses are formed due to the distortion of pore water pressure,which has a precautionary significance for roof water inrush in shallow coal seam.In order to obtain the spatial-temporal responding mechanism between pore water pressure in aquiclude and roof water inrush,aquiclude was simplified into saturated porous in liquid-solid media and a viscoelastic dynamics model was built to obtain the analytical solution of the pressure distribution.The fluid-solid coupling model was constructed with a simulation software and the characteristics of the pressure change overburden in different mining intensity conditions were analyzed;based on the solid-liquid coupling test platform,evolution experiments of water inrush in shallow buried coal seam were carried out to further reveal and verify the correspondence between the pressure and inrush under mining disturbance and seepage.This research has showed that the pore water pressure is closely related to mining disturbance.After mining disturbance,the pore water pressure soars to its peak followed by a rapid drop.The water-resisting property disappears,leading to water inrush on the roof,and then the pore water pressure fluctuates at a relatively low level.The study lays a foundation for the establishment of roof water inrush early-warning system in the water-rich area.