A model to evaluate the transient hydraulic response of three‐dimensional sparsely fractured rock masses

A numerical model is presented for the analysis of transient fluid flow in large systems of rigid fissure discs. A boundary element procedure is invoked to minimize the number of equations required to define the system. Condensation of the system of equations at an elemental or individual disc level is used to cast the solution into finite element format. The resulting global matrices are well conditioned, sparsely populated, and apparently symmetric. The formulation is illustrated to perform well in validation studies for both single unconnected and multiply connected fissures. The procedure is ideally suited to the analysis of large, formerly intractable, fissure networks where the system degrees of freedom may be reduced to and retained at a minimum.