A dual-scale fracture network model for computing hydro-mechanical properties of fractured rock

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.

Automated summary

This study introduces a dual-scale fracture network model to simulate the distribution of large and small fractures in fractured geological media. By discriminating between different length scales and using upscaling treatment, the model accurately calculates the bulk properties of the rock mass.