裂隙岩体非线性渗流特性分析

Analysis on non-Darcy flow characteristic for fractured rock

开展了不同围压下的裂隙岩体渗流试验,提出了一种简单的裂隙隙宽测量方法,并研究了渗流过程裂隙的变形特征;基于Forchheimer非线性渗流方程,计算了非线性系数及渗透率,分析了围压与非线性系数及渗透率的关系。研究结果表明,随着围压增大,岩样的渗透率减小,非线性渗流系数增大;裂隙粗糙度越大,越容易引起非线性渗流;裂隙水力开度与力学开度随围压变化趋势一致,水力开度约为力学开度的5%。

A series of flow tests on fractured rock are conducted under variable confining pressures.A simple measurement method for measuring fracture aperture is proposed,and fracture deformation is studied during the flow tests.Subsequently,the nonlinear flow coefficient and permeability were calculated based on the Forchheimer equation.The relation of confining pressure with nonlinear flow coefficient and permeability are investigated.The research results show that the permeability decreases with the increase of confining pressure,while the nonlinear flow coefficient increases.In addition,rougher fracture surface helps to stronger nonlinearity.The change trend of hydraulic aperture with confining pressure is similar to the curve of mechanical aperture versus confining pressure.It is found that the hydraulic aperture is 5%of mechanical aperture.