浅埋煤层开采突水溃砂的颗粒流模拟研究

Water-sand inrush simulation under shallow coal mining based on the particle flow code

为研究浅埋煤层开采下突水溃砂的覆松散层渗透破坏、水砂耦合流动及突涌规律,指导预防突水溃砂灾害的发生提供依据,采用二维颗粒流软件PFC2D分别对上覆松散层渗透变形破坏、水砂混合流运移过程进行数值模拟研究,建立了浅埋煤层开采突水溃砂的数值模拟模型。结果表明:上覆松散含水层的初始水压力与裂隙通道的宽度对松散层的渗透变形破坏过程有较大影响。当含水层初始水压力增加时,裂隙处流体的流速、颗粒间的接触应力均明显增加,且呈现出非线性增长趋势;水砂混合流的突出时间以及突出速度与裂隙通道的倾角、粗糙度相关。同时根据水砂混合流的Y方向突出速度大小的波动变化规律,预测了2种可能存在的水砂突出类型;含水层的初始水压力影响突水溃砂的发生及运移过程,由此提出了通过疏放松散层水来预防突水溃砂灾害发生的方法。

For the research of the seepage-deformation of aquifer, the flow regularity of mixed water-sand flow, the inrush law of mixed water-sand under the shallow coal seam mining, and providing a basis of guidance to prevent water-sand inrush disasters from happening, the particle flow code in two dimensions （ PFC2D） is employed to simulate the seepage deformation failure of loose overburden and the character- istics of mixed water-sand flow, respectively. Establish the numerical simulation model of water-sand in- rush under shallow coal seam. Results show that ： The intial water pressure of overlying loose aquifer and the width of fracture channels affect the process of seepage-deformation failure. When the intial water pressure of aquifer increased the speed of fluid in the fracture and the contact stress between particles increase apparently and nonlinearly. The inrush time and speed of mixed water-sand flow have link with the rough and obliquity of fracture channels. Meanwhile two potential types of the mixed water-sand in- rush were carried out according to the fluctuation of the Y dirction inrush speed. Since the initial water pressure of aquifer affect the happen and flow process of the water-sand inrush, draining away bottom wa- ter may give an potential approach to preventing and solving the disaster of water-sand inrush.