基于流固耦合效应的岩层渗透系数演化规律与断层活化突水数值模拟研究

Study on evolution law of rock permeability coefficient under influence of fluid structure coupling effect and numerical simulation of fault activated water inrush

针对断层活化突水数值研究过程常忽略流固耦合效应的影响且各层位渗透系数常设为固定值的弊端,采用FLAC3D有限差分软件建立采动断层活化突水数值计算模型,并基于Fish语言编制断层及顶底板岩层在弹性及塑性范围内渗透系数随有效应力、初始孔隙率、残余孔隙率等变化的程序,用于采动断层活化突水数值计算,在考虑塑性区及孔隙压力、渗流矢量变化的基础上,分析了不同水压对断层活化突水的影响规律。结果表明,断层活化范围与承压水水压呈正相关的关系,当模型水压分别为3.0、3.5 MPa时,断层上部及底部发生了活化而中部未发生活化现象;当水压为4.0 MPa时,煤层底板断层整体发生了活化。通过对理论公式的赋参计算,得到了临界突水水压为3.97 MPa,验证了数值结果的正确性。

In view of the fact that the influence of fluid-structure coupling effect is often ignored in the numerical study of water inrush caused by fault activation and the permeability coefficient of each layer is always fixed, the numerical calculation model of water inrush caused by mining fault activation is established by using FLAC3Dfinite difference software, and the program for the change of permeability coefficient with effective stress, initial porosity, residual porosity, etc.In the elastic and plastic range of fault and top and bottom slate is compiled based on Fish language, it is used for the numerical calculation of water inrush caused by mining fault activation.On the basis of considering the change of plastic zone, pore pressure and seepage vector, the influence law of different water pressures on water inrush caused by fault activation is analyzed.The results show that there is a positive correlation between the fault activation range and the confined water pressure.When the model water pressure is 3.0 MPa and 3.5 MPa respectively, the upper and lower parts of the fault are activated, but the middle part is not activated.When the water pressure is 4.0 MPa, the coal seam floor fault is activated as a whole.Through the parameter calculation of the theoretical formula, the critical water inrush pressure is 3.97 MPa, which verifies the correctness of the numerical results.