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浅埋煤层地下水库流固耦合模型特征参数试验研究

Experimental study on feature parameters of fluid-solid coupling model ofunderground reservoir in shallow depth seam

  • 摘要: 煤层采动引起的岩体运移、裂隙演化与渗流特性对煤矿地下水库的设计建造具有重要影响,为获取地下水库围岩体物理特征参数,开展相似材料流固耦合模型试验研究,结合典型浅埋煤层水文地质及开采条件,建立了立体相似材料流固耦合模型。通过监测煤层开挖过程中顶板下沉量、煤柱应力、含水层渗压等特征参数的变化,研究了煤层采动过程中破断岩体运移、裂隙演化规律及扰动岩层渗流特性变化规律。试验结果表明:煤层开挖后,煤柱上覆岩层形成倒台阶结构,煤柱应力先增大后减小。顶板岩层先后经历“弯曲下沉—裂隙发育—破断垮落”的动态演化过程,岩层裂隙发育程度决定了形成的导水裂隙带数量,可用岩层渗压下降速率表征岩层裂隙发育程度。岩层大面积垮冒滞后于导水裂隙带形成,含水层渗压突变先于岩层突降下沉发生,可将含水层渗压突降作为顶板来压垮冒的预兆之一。

     

    Abstract: A rock mass migration,crack evolution and seepage features caused by the seam mining could be highly affected to the design and construction of the underground water reservoir.In order to get the physical features and parameters of the surrounding rock mass in the underground water reservoir,an experiment study was conducted on a fluid-solid coupling model of the similar material.In combination with the hydrogeological and mining conditions of the typical shallow depth seam,the fluid-solid coupling model of the 3D similar material was established.With the monitoring and measuring on the variations of the roof subsidence,coal pillar stress,aquifer seepage pressure and other feature parameters during the mining and excavation process of the seam,a study was conducted on the broken rock mass migration,crack evolution law and the disturbance rock seepage features varied law during the mining process of the seam.the experiment results showed that after the excavation of the seam,the overburden strata above the coal pillar would form a inverted step structure and the coal pillar stress would be firstly increased and then decreased.The rock strata of the roof before and after experienced a dynamic evolution process of “bending subsidence - crack development - broken collapse”.The crack development degree of the rock strata would determine the number of the formed water flowing crack zone.The seepage pressure decreased rate of the rock strata could be applied to characterize the crack development degree of the rock strata.A large area collapsing of the rock strata would lag behind the formation of the water flowing cracks.A sudden changed seepage pressure of the aquifer would be before the sudden subsidence occurred.A sudden reduced seepage pressure of the aquifer could be one of the foretastes to the roof weighting and collapsing.

     

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