A Large-Scale Flow and Tracer Experiment in Granite: 2. Results and Interpretation

Water and tracer flow has been monitored in a specially excavated drift in the Stripa mine. Several new experimental techniques and equipment were developed and used. The whole ceiling and the upper part of the walls were covered with 375 individual plastic sheets where the water flow into the drift could be collected. Eleven different tracers were injected at distances between 11 and 50 m from the ceiling of the drift. The flow rate and tracer monitoring was kept up for more than 2 years. The tracer breakthrough curves and flow rate distributions were used to study the flow paths, velocities, hydraulic conductivities, dispersivities and channeling effects in the rock. In a companion paper the experimental design and performed experiments are described. The present paper describes the interpretation of flow and tracer movement in the rock outside the drift. The tracer movement was measured by the more than 160 individual tracer curves. The tracer experiments have permitted the flow porosity and dispersion to be studied. The possible effects of channeling and the diffusion of tracers into stagnant waters in the rock matrix and in stagnant waters in the fractures have also been addressed.

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