底部含水层孔隙水压力采动波动及影响机制的试验研究

Experiment Study of Pore Water Pressure Fluctuation and Influence Mechanism in Bottom Aquifer during Mining

涌水溃砂是松散层底部砂土含水层和薄覆岩下煤炭开采的典型地质灾害,如能够掌握砂土层中采动水压力动态变化规律,捕捉涌水溃砂的前兆信息,将会起到灾害预警和提升开采安全水平的作用。以刘河煤矿13021工作面为地质原型,以松散层底部受开采影响的砂土含水层为研究对象,通过建立水压力监测相似模型,分析了2个分层开采过程中覆岩变形破坏特征及底部含水层砂土孔隙水压力动态变化过程,并由此建立了水压力波动与覆岩变形破坏程度之间的联系。研究认为,覆岩移动控制着上覆土体变形,每次覆岩下沉至稳定的过程中,各监测点均会出现明显水压力波动现象,远离开切眼的监测点水压力变化明显滞后;覆岩下沉量与剧烈程度控制着水压力变化幅值。

Water and sand inrush is a typical geological disaster in coal mining under bottom sand aquifer and thin overburden rock mass,therefore,to master the dynamic variation law of water pressure in sand aquifer and capture the precursor information of water and sand inrush during mining will play a role of early warning and enhancement of mining safety level. In this paper,13021 working face in Liuhe Coal Mine was taken as the geological background,the sand aquifer under the unconsolidated layers affected by mining was taken as the research object. Through the establishment of the similar model of water pressure monitoring,analysis was carried out on the deformation and failure characteristics of the overburden rock mass and the dynamic variation,based on this,a relation between the water pressure fluctuation and the failure extent of overburden rock mass was established. The studies showed that the deformation of the overlying soil layer was controlled by the movement of the overburden rock mass,in each subsidence process of overburden rock,the water pressure at each monitoring point would show significant fluctuation,and the water pressure variation at the monitoring point far from the starting cut variously lagged;the subsidence amount and intensity of the overburden rock mass would control the variation amplitude of water pressure.