CHANNELING EXPERIMENTS IN CRYSTALLINE FRACTURED ROCKS

The channeling experiments were designed to study the transmissivity and aperture variations in fractures in crystalline rock at a depth comparable to high-level waste repository depths. The experiments were performed in the Stripa experimental mine in mid-Sweden. Two types of experiments were designed. In the single-hole experiments a hole was drilled > 2 m into the plane of the fracture and injection flow-rates were measured in 5-cm sections using a specially designed injection packer. Photographs were also taken inside the hole along the fracture to determine the visible fracture aperture and to obtain other information such as fracture intersections and fracture infilling. In the double-hole experiment two parallel holes were drilled in the plane of the same fracture at a center distance of 1.95 m. Hydraulic tests and tracer tests were made between the two holes to obtain information on connections in the plane of the fracture and to obtain information on residence time distributions in different paths (channels).