Modeling of fluid flow is important in geological, petroleum, environmental, civil and mining engineering. Fluid flow through jointed hard rock is very much dependent on the fracture network pattern in the rock mass and on the flow behavior through these fractures. Flow behavior through a single fracture depends on the spatial distribution of the aperture including their connectivity, the contact area distribution of the fracture and fluid properties. The aperture and the contact area distributions of a fracture depend on the stress system acting on the joint. This research deals with fluid flow behavior through single joints subjected to normal stresses. The features of the built equipment and various phases of the laboratory experimental program are described in the paper. The initial test results obtained between applied normal stress and fracture closure for a natural rock joint indicate the built equipment works very well in obtaining normal stress versus fracture closure measurements. Fluid flow tests performed for the same rock joint under different normal stresses proved that the built fluid flow experimental system performs very well. Spatial distribution of aperture calculated at different normal stresses using rock joint surface height measurements obtained through a laser profilometer with and without silicon rubber injection to the same rock joint showed that the experimental procedure developed to estimate the spatial distribution of aperture of a rock joint works well.
Modeling of fluid flow through jointed rock is important in performing the following tasks associated with jointed rock masses: (a) characterization and development of fractured rock oil reservoirs, (b) geothermal energy development, (c) petroleum well design, (d) nuclear waste repository performance assessment studies, (e) interpretation of hydrologic tests, (f) design of in-situ hydrologic tests, (g) groundwater contamination studies, (h) in-situ mine leaching studies, and (i) stability studies of rock masses in the presence of groundwater flow. In general, fluid flow through jointed rock depends on the following factors: (a) stratigraphy, (b) fracture network pattern, (c) flow behavior through single fractures, (d) flow properties of matrix rock, (e) in-situ stressystem and (f) hydraulic boundary conditions. For sedimentary rocks, the matrix permeability is significant compared to the hydraulic conductivity of fractures. Therefore, all the aforementioned factors should be considered in modeling fluid flow through the rock mass. However, for most of the igneous and metamorphic rocks, the matrix permeability is negligible compared to the hydrauliconductivity of fractures. Therefore, for such rock masses, fluid flow through jointed rock is very much dependent on the fracture network pattern in the rock mass and on the flow behavior through these fractures. Discrete fracture flow models have been suggested in the literature (Schwartz et al., 1983; Robinson, 1984; Pruess, 1987; Karasaki, 1987; Kulatilake et al., 1999) to simulate fluid flow through jointed hard rock masses. To use these models, at present, a realistic model is not available to represent fluid flow through single joints. This study initiates research to overcome this shortcoming. Flow behavior through a single joint depends on the spatial distribution of the aperture including their connectivity, the contact area distribution of the joint and fluid properties. The aperture and contact area distributions of a joint depend on the type of the fracture (tensile, shear or mixed mode), the stress system acting on the joint, and the stress history of the joint. Stresses acting on a joint can be separated into normal and shear stresses. This
