岩体中充满着裂隙，它对油气资源开发、地下水资源利用、污染物迁移、二氧化碳封存以及核废物地质处置等具有重要意义，因此，必须评估裂隙对岩体渗透率的影响。一般来说，通过盘状裂隙网络渗流模型分析裂隙连通性和渗流特性的方法有3种：有限元法；离散元法；将DFN转换为与平面裂缝具有近似等效连接性和水力特性的网络管道，也称为“管网模型”。对我国高放射性废物处置库新场花岗岩露头进行了研究，使用变截面等效管来模拟岩体裂缝的渗透特性，将复杂的裂隙盘网络等效为管网模型，并提出等效路径渗透系数来客观研究裂隙岩体渗流路径的渗透特性。当新鲜裂缝通过切割地表岩石暴露到一定深度时，某些走向范围内的裂缝属于张开型，而另一个走向范围内的裂缝属于胶结闭合型。不同条件下的等效路径渗透系数计算结果表明，裂缝胶结及部分胶结时，等效路径渗透系数平均值的量级分别为10^-7 m/s和10^-3 m/s。在此基础上，确定研究区裂隙岩体的代表性单元体积（REV）约为25 m³，通过旋转模型中的矩阵，得到该区域的空间渗透张量（包括渗透值和主方向），且所预测结果在钻孔资料范围内，可为相关工程提供参考。

The lower rock mass is filled with fissures,which is of great significance for oil and gas resource development,groundwater resource utilization,pollutant migration,carbon dioxide storage,and nuclear waste geological disposal. Nuclear waste repository has extremely strict requirements for geological environment. However,the natural fractures in rock mass may be the potential channel for nuclide migration. Therefore,it is necessary to evaluate the impact of fractures on rock permeability. In general,there are three methods to analyze the fracture connectivity and seepage characteristics through the disc-shaped fracture network seepage model:the finite element method; the discrete element method; the DFN is converted into a plane crack with similar network pipes with effective connectivity and hydraulic characteristics are also called "pipe network models". In this paper,the granite outcrop of Xinchang high-level radioactive waste repository in China is studied. Variable-section equivalent pipes to simulate the permeability characteristics of rock fractures is used. The complex fissure disk network is equivalent to a pipe network model. An equivalent path permeability coefficient is proposed to objectively study the permeability characteristics of the seepage path of the fractured rock mass. When the fresh fractures are exposed to a certain depth by cutting the surface rocks,some fractures in the strike range belong to open type,others belong to the cemented closed type. The calculation results of equivalent path permeability coefficient under different conditions show that the average values of equivalent path permeability coefficient are 10^-7 m/s and 10^-3 m/s respectively when the fracture is cemented and partially cemented. On this basis,the representative unit volume(REV) of fissured rock mass in the study area is determined to be about 25 m. Through the matrix in the rotation model,the spatial permeability tensor(including permeability value and main direction) of the area is obtained,and the predicted results are within the range of borehole data,which can provide reference for related projects.

0 引言

1 研究背景及等效管网模型的渗流分析

2 渗透张量的计算

3 结论