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为了研究层流状态下粗糙单裂隙面的渗流特性,基于格子Boltzmann方法,建立了压力作用下单裂隙面渗流的数值模型。采用D2Q9模型模拟离散速度分布方向,在宏观尺度上,上、下边界设置为不透水边界(u_x=u_y=0),左、右边界为压力边界(左侧压力p_(in)大于右侧压力p_(out))在微观尺度上,左、右边界及光滑裂隙表面采用非平衡态外推格式,粗糙裂隙表面采用标准反弹格式。编制了相应的计算程序,验证了光滑平板裂隙流的立方定律。采用分段随机裂隙长及裂隙宽的方法生成了粗糙裂隙面,并基于格子Boltzmann方法研究了不同粗糙裂隙面方案的渗流特性。研究结果表明:对于粗糙裂隙面,渗流特征极大程度取决于裂隙表面形貌,随着相对粗糙度的增加,裂隙渗流规律明显偏离立方定律。为此,考虑裂隙面相对粗糙度的影响,根据不同裂隙粗糙面方案的数值计算结果,提出了层流状态下粗糙裂隙面渗流的立方定律修正公式,为系统研究复杂粗糙裂隙的水力特性奠定了一定的基础。
In order to study the seepage characteristics of a single rough fracture surface under laminar flow, a numerical model of seepage flow in a single fracture surface under pressure is established based on the lattice Boltzmann method. In the macro scale, the upper and lower boundaries are set as impervious boundary (u_x = u_y = 0), the left and right boundary are the pressure boundary (left pressure p_ (in) is greater than the right pressure p_ (out)) At the microscopic scale, the non-equilibrium extrapolation format is used for the left and right boundaries and the smooth fracture surface, and the rough fracture surface is in the standard rebound format. The corresponding calculation program is compiled to verify the cubic law of smooth plate fracture flow. The rough crack surface is generated by using the method of stochastic crack length and crack width, and the seepage characteristics of different rough crack surface schemes are studied based on the lattice Boltzmann method. The results show that for the rough fracture surface, the seepage characteristics greatly depend on the fracture surface morphology. With the increase of the relative roughness, the fracture seepage law obviously deviates from the cubic law. Therefore, considering the influence of the relative roughness of the fracture surface, a modified formula of the cubic law of the seepage flow through the rough fracture surface under the condition of laminar flow is proposed according to the numerical calculation results of different fracture rough surface schemes, which lays the foundation for systematically studying the hydraulic characteristics of the complex rough fracture A certain basis.