定量描述交叉裂隙的渗流特性是明确整个裂隙网络渗流特性的基础。制作三维人工交叉裂隙模型,建立高精度渗流测试系统;求解Navier-Stokes方程,模拟流体在三维交叉裂隙内的流动状态,对裂隙宽度的取值标准进行探讨。结果表明,室内实验得到的流速Q和压力P具有二次项关系,可以用Forchheimer方程描述;通过理论推导和数值模拟计算得到的单裂隙段的Re和实验结果基本吻合,验证了实验结果的正确性及数值模拟的可靠性;根据研究,交叉裂隙的宽度应大于最大裂隙开度的8倍,流体的流动状态由线性转入非线性的临界Re的范围为12.33-61.67。
Fracture intersection plays a basic role in fluid flow and solute transport through fracture networks because they allow different fluids to mix and disperse along the flow paths. An artificial three dimensional crossed fracture model is manufactured and a high-precision experimental system of fluid flow test was established. Numerical simulations by solving the Navier-Stokes equations were performed to investigate the fluid flow behavior through crossed fractures with different widths. The results show that the flow rate is quadratically related with the tested pressure drop,following the famous Forchheimer's law. The Reynolds numbers(Re) of the tested results agree well with those of numerical simulations and theoretical solutions,indicating that both the experiments and simulations are reliable. This work suggests that the suitable width of fractures in a fracture model should be 8 times larger than the maximum hydraulic aperture of all fractures. The critical Re for the onset of nonlinear flow through crossed fractures is in the range of 12.33–61.67.