In natural rock masses, the shapes of three‐dimensional (3‐D) blocks cut by arbitrary fracture networks may be very complex. Owing to the geometric complexity and difficulty of mesh discretization of 3‐D blocks and fracture facets, explicit consideration of fracture networks in flow analysis of fractured porous medium (FPM) is very challenging. Using the numerical manifold method based on independent covers (NMMIC), an FPM flow model was proposed that can deal with very complex 3‐D fracture networks. In this paper, the convergence of NMMIC was first demonstrated. The theoretical basis of the arbitrary refinement of computational meshes was proven. Moreover, three peculiarities of NMMIC meshes, that is, arbitrary shape, arbitrary connection, and arbitrary refinement of independent covers, were concluded. Finally, some two‐dimensional (2‐D) tunnel flow examples were analyzed and the numerical results were compared with the analytical results. 3‐D examples with complex fracture distributions were also analyzed. In addition, the computational scale of the developed program was tested by increasing the number of computational elements. The results show that our model can accurately analyze the groundwater flow of rocks surrounding tunnels with complex fracture distributions.

中文翻译：

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基于NMM的压裂多孔介质流动模型的论证与应用

在天然岩体中，由任意裂缝网络切割的三维（3D）块的形状可能非常复杂。由于3D块和裂缝面的网格离散的几何复杂性和难度，在裂缝性多孔介质（FPM）的流动分析中明确考虑裂缝网络非常具有挑战性。使用基于独立覆盖层（NMMIC）的数值流形方法，提出了一种FPM流模型，该模型可以处理非常复杂的3D裂缝网络。本文首先证明了NMMIC的收敛性。证明了任意细化计算网格的理论基础。此外，总结了NMMIC网格的三个特点，即任意形状，任意连接和对独立覆盖物的任意细化。最后，分析了一些二维（二维）隧道流动实例，并将数值结果与分析结果进行了比较。还分析了具有复杂裂缝分布的3D实例。另外，通过增加计算元素的数量来测试所开发程序的计算规模。结果表明，该模型能够准确地分析裂缝分布复杂的隧道周围岩石的地下水流。