Analytical Solution and Numerical Simulation of Steady Flow Around a Circular Heterogeneity With Anisotropic and Concentrically Varying Permeability

Abstract

AbstractAccurately simulating flow to assess the environmental impact of backfilled mine open‐pit with hazardous waste is challenging. Excavation and blasting during mining operations often result in the creation of new fractures with preferential orientation, which leads to a variable and anisotropic permeability field around the excavation. Numerical simulations are often used to study such problems, but experimental data are scarce and analytical solutions for this configuration are not available in the literature, which make the code validation difficult and uncertain. Therefore, the present study aimed to address the numerical code validation by developing a new closed form head solution of a steady flow with a radially anisotropic and continuously varying permeability distribution around a heterogeneity. Numerical flow simulations using the finite volume code PFLOTRAN were then compared to the analytically calculated heads and flowrates on three cases of increasing complexity. Results showed a good agreement between analytical and simulated flowrates and heads, with a maximum absolute error not exceeding 3.5% on flowrates and 1.8% on heads. Errors were actually mainly caused by boundary effects and by the non‐respect of the K‐orthogonality condition in the computational mesh. This study opens the way for accurate evaluation of the blast damage zone influence on groundwater flow in and around open pits backfilled with hazardous wastes.