Comparison of numerical and analytical models of unsaturated flow around underground openings
Mining Engineering
, 2001, Vol. 53, No. 12, pp. 25-28
Hughson, D.L.; Codell, R.
ABSTRACT:
Performance calculations for the proposed repository at Yucca Mountain, NV are sensitive to estimates of water dripping into waste emplacement drifts. In the performance assessment for the Viability Assessment (US Department of Energy, 1998), abstraction for seepage flux magnitude and fraction of affected waste packages were based on a three-dimensional, heterogeneous, porous continuum representation of flow through the fracture network in Topopah Springs welded tuff. Simulations using the TOUGH code (Birkholzer et al., 1999) showed reasonable agreement with analytical solutions. The author’s tested the integrated, finite-volume, two-phase water–energy flow and reactive transport code MULTIFLO 1.2?, developed at the Center for Nuclear Waste Regulatory Analyses (Lichtner and Seth, 1998). They benchmarked it against the analytical solution of Philip et al. (1989) for horizontal cylindrical underground openings. This analytical result gives the magnitude of infiltration and deep percolation flux that is the threshold for dripping to occur into the cavity, assuming a homogenous porous medium characterized by an exponential relative permeability model (Gardner, 1958) and steady-state flow.
