Analysis of Seepage Flow in a Rock Mass Using the Discrete Model

The importance of seepage flow through a rock mass for the planning and construction of dams, slopes and openings has already been mentioned in Section 5.1. It has also been mentioned that the consideration of steady state problems is sufficient to cover most cases in rock engineering. Two conceptual models were formulated in Section 5.3 to provide the basis for the analytical treatment of seepage flow. Both employ friction factor equations for flow through discontinuities. It was demonstrated that the losses arising at the intersections between discontinuities of differing families could usually be neglected and that the piezometric head in each discontinuity immediately adjacent to the intersection could be assumed to be equal (5.60). The so-called discrete model was developed both from this assumption and the application of the continuity condition at the intersections (5.61), the model treating seepage flow as a sequence of flow processes through a grid of discontinuities (Section 5.3.1). A method of analysis for the investigation of two-dimensional (Section 9.2) and three-dimensional (Section 9.3) problems will now be developed on the basis of this model.