Numerical simulation experiments on water seepage patterns in heterogeneous, unsaturated rock fractures

摘要

Water seepage has been numerically simulated in heterogeneous fractures, which were conceptualized as two-dimensional heterogeneous porous media. Flow was found to proceed in dendritic patterns along preferential paths, giving rise to such features as localized ponding and bypassing. Limited parameter variation studies have shown strong dependence of seepage patterns on fracture permeability and applied flow rate. The temporal evolution of seeps proceeds on a vast range of time scales. This casts doubt on the applicability of steady-state concepts for water migration in thick unsaturated zones of fractured rock where infiltration is episodic. An approximate invariance of seepage behavior was derived for simultaneous space-and-time scaling. Numerical simulation experiments have confirmed this invariance, as well as its limits of applicability.