Fractured geological media often consist of a large number of discontinuities that exist over many different length scales and are associated with scale-dependent hydro-mechanical properties. This raises a great challenge for modelling such hierarchical systems using single scale-based simulations. To overcome this hurdle, in this Note, we propose a dual-scale fracture network model, which explicitly represents the distribution of large-sized fractures while also implicitly respects the contribution of small-sized fractures via an upscaling treatment. We discriminate large and small fractures according to a prescribed length scale (determined via a numerical convergence examination), based on which the domain is discretised into a mesh of grid blocks. A modified crack tensor method is employed to derive the equivalent hydro-mechanical properties of each block containing (entirely or partially) the small-sized fractures. It is shown that the bulk properties of the rock mass can be robustly calculated by this dual-scale model at high accuracy.

断裂的地质介质通常由大量不连续性组成，这些不连续性存在于许多不同的长度尺度上，并与与尺度相关的水力学特性有关。这对使用基于单一尺度的模拟对此类分层系统进行建模提出了巨大挑战。为了克服这个障碍，在本说明中，我们提出了一个双尺度裂缝网络模型，它明确地表示了大尺寸裂缝的分布，同时也通过放大处理隐含地尊重了小尺寸裂缝的贡献。我们根据规定的长度尺度（通过数值收敛性检查确定）区分大小裂缝，在此基础上将域离散为网格块。采用改进的裂纹张量方法推导出包含（全部或部分）小尺寸裂缝的每个块的等效流体力学特性。结果表明，该双尺度模型可以高精度地稳健计算岩体的整体特性。