低渗透各向异性裂隙岩体渗透性探讨

Research on the Permeability of Low-permeable and Anisotropic Fractured Rock Mass

针对低渗透性裂隙岩体介质的各向异性特征,考虑并简要分析了实验室法、现场测试法、裂隙采样测量法和反演法确定裂隙岩体渗透张量的优缺点,提出了用现场测试修正裂隙采样测量裂隙岩体渗透张量的方法。获得了既能较好反映裂隙岩体渗透特性的各向异性又能消除压水试验尺寸效应影响的修正渗透张量,从而使裂隙岩体的渗透性能得到真实的量化。将这种确定渗透张量的方法应用于黄河上游某水电站坝址区岩体渗透性计算中,应用结果表明,该方法能较好地反映坝址区的裂隙岩体的低渗透性及其各向异性特征,可为岩体渗透性分区及防渗帷幕的优化提供科学的参考依据。

According to the anisotropic characters of the low-permeability fractured rock mass, based on an analysis of advantages and disadvantages of using laboratory method, in-situ test, fissure sample measuring method and inversion method to determine the permeability tensor of fractured rock mass, it is suggested that in-situ tests be used to modify the tensor obtained by fissure sample measuring method in this paper. Then, this method can better depict the anisotropism of permeability characteristics of fractured rock mass and the modified permeability tensor can eliminate the non-penetrability of fissures and fills and the size effect of the pump -in test, so that the permeability of fractured rock mass can be quantified. The proposed method is used in the calculation of the per- meability rock mass of some hydropower stations in Upper Yellow River. The results show that the method can better reflect the low -permeability and anisotropic character of the permeability of fractured rock mass. It can also provide a scientific basis for the permeability zoning of rock and optimization of impervious curtain.