采动覆岩隔水层稳定性力学模型及应用研究

为了研究覆岩隔水层的稳定性,预防煤矿顶板突水灾害,实现保水采煤,本文将单一岩层形成的顶板隔水层简化为地基上四边固支的薄板,考虑了隔水层以下破碎岩体对隔水层的支撑作用,根据能量法推导了其挠度以及应力表达式,得到了覆岩隔水层应力分布特性,求出了临界载荷随工作面推进距离的变化规律,并结合具体工程实例,利用数值模拟软件进行了覆岩隔水层稳定性分析。研究结果表明:1)煤层开采后,覆岩隔水层在长边边缘中间应力最大,容易发生破坏;2)破碎岩体的支撑作用对隔水层的稳定性具有重要的影响,煤层采厚越小,破碎岩体对覆岩隔水的支撑作用越强,隔水层越不容易破断。研究成果可为煤矿顶板防治水研究以及保水采煤实践提供一定的参考。

Mechanical Model of Stability of Water-Resistant Strata Under Mining and Its Application

In this paper,to research the stability of overlying water-resistant strata and prevent the roof water inrush accidents as well as implement water-preserved-mining,we regarded the water-resistant strata composed by only one rock stratum as clamped rectangular thick plate on foundation,and took the support effect of broken rock mass under the water-resistant strata into account,then deduced the deflection and stress expression according to energy method,and obtained the stress distribution characteristics of overlying water-resistant strata,as well as the variation rule of critical load along with working face advancement.In addition,combined with specific engineering practice,the stability of overlying water-resistant strata was analyzed by numerical simulation.The results indicate that: 1) after coal seam mining,the stress of overlying strata reaches the maximum value in the middle of longer boundary of the plate,where the rock is easy to be damaged;2) the supporting effect of broken rock mass have important influence on the stability of overlying water-resistant strata,that is,the thinner the mining thickness is,the stronger the supporting effect of broken rock mass to the overlying water-resistant strata is,and the more difficult the water-resistant strata to be broken.The research results can provide some reference for the prevention of roof water inrush and water-preserved-mining practice.