CHANNELING EXPERIMENTS IN CRYSTALLINE FRACTURED ROCKS

The channeling experiments were designed to study the transmissivity a nd aperture variations in fractures in crystalline rock at a depth com parable to high-level waste repository depths. The experiments were pe rformed in the Stripa experimental mine in mid-Sweden. Two types of ex periments were designed. In the single-hole experiments a hole was dri lled > 2 m into the plane of the fracture and injection flow-rates wer e measured in 5-cm sections using a specially designed injection packe r. Photographs were also taken inside the hole along the fracture to d etermine 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 sa me fracture at a center distance of 1.95 m. Hydraulic tests and tracer tests were made between the two holes to obtain information on connec tions in the plane of the fracture and to obtain information on reside nce time distributions in different paths (channels).