Understanding water inrush hazard of weak geological structure in deep mine engineering: A seepage-induced erosion model considering tortuosity

Abstract

Tortuosity is an important parameter to understand the formation mechanism of water-conducted pathways in deep mine engineering. In this study, a numerical method was proposed to calculate the tortuosity of fractured fault rocks. Convergence tests show that the simulation method has high accuracy. The evolution of tortuosity is consistent with previous studies: it can be divided into four stages, i. e., rearrangement of rock particles, particle migration, continued seepage, and steady water flow. There is an exponential relationship between tortuosity and porosity of fractured rock mass. A new concept (porous tortuosity index) was proposed in this study, which can reflect the spatial distribution of particles and particle size distribution of the fractured rocks and is not affected by the flow behavior of water. In addition, the seepage erosion model considering the tortuosity of the fractured rock mass can improve the calculation accuracy of permeability, non-Darcy coefficient and Forchheimer coefficient, which is fundamental for the prediction of water inrush in weak geological structures.

Keywords

tortuosity / non-Darcy hydraulic properties / numerical simulation / fractured rock mass / seepage erosion

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