A review of existing methods used to evaluate the hydraulic conductivity of a fractured rock mass
We review the existing methods for evaluating the hydraulic conductivity of a rock mass. Rock mass permeability may be assessed using empirical, analytical and numerical approaches. Empirical methods use data from in situ field tests to derive the relationship between depth and permeability by applying a curve-fitting method and establishing the relationship between hydraulic conductivity and a geological index. Analytical methods rely on Darcy and cubic laws to estimate the permeability of a rock mass by taking into account the geometrical characteristics of the joint sets. Analytical equations of the flow rate into underground excavations are also developed by solving the Laplace equation for homogeneous and isotropic aquifers under various boundary conditions. Numerical modeling can evaluate the outcomes of both empirical and analytical approaches (and vice versa) and can provide a sensitivity analysis of the parameters that affect rock mass permeability. The importance of stress and joint set characteristics is often investigated via numerical modeling, as are the scale effect and directional permeability. In this review paper, we provide a comprehensive review of these approaches for studying rock mass permeability. We summarize the advantages and disadvantages of existing methods and highlight potential future research directions.
Keywords: Hydraulic conductivity, Permeability, Rock mass, Empirical method, Analytical model, Numerical model