This paper describes a series of dipole tracer tests using an array of boreholes at Kamaishi Underground Test Site. Iwate, Japan. A comprehensive geohydrological survey prior to the tracer test revealed complicated hydraulic connections within a test area. The transport aperture obtained for single fractures was found to be an order of magnitude larger than the hydraulic aperture. The longitudinal dispersion length clearly showed a scale dependency and found to be approximately one tenth of migration length.
Cet expose decrÍt une serie de sondages en doublet par le traceur à l'aide d'une rangee de trous de sondage realses au chantier d'essai souterrain de Kamaishi, Iwate au Japon. Une investigation detaillee et complète effectuee prealablernent aux sondages par le traceur a revele la cornplexite du systeme hydraulique existant dans la zone sendee, Les dimensions de la "voie de matière (transport aperture)" determinees par les sondages des fractures isolees sont plus importantes que celles de la "voie hydraulique (hydraulic aperture)". La longueur de dispersion longitudinale montre clairement qu'elle est influencee par l'echelle et que cette longueur equivaut à un dixième de la longueur de migration.
Diese Studie beschreibt eine Serie von Dipol-Tracer-Tests mit einer Anordnung von Bohrlöchern an der Kamaishi- Untergrund- TeststeUe in Iwate, Japan. Eine umfassende geohydrologische Untersuchung vor dem Tracer-Test zeigte komplizierte hydraulische Verbindungen innerhalb des Testbereichs. Die fuer Einzelrisse erhaltene Transportöffnung erwies sich urn eine ganze Grö- Benklasse größer als die hydraulische Öffnung, Die Lange der Langsverteilung zeigte deutlich eine Skalenabhangigkeit und erwies sich als etwa ein Zehntel der Wanderlange.
A comprehensive study on fluid flow and mass transport properties of fractured granite was conducted at the underground test site at Kamaishi Mine in Japan. The test consists of the three major stages:
geometrical and geological fracture system characterization.
hydraulic characterization of the fracture system including flow logging to 1 m resolution. interference pressure tests and pressure monitoring using multiple piezometer system. and
dipole tracer tests.
This paper describes a systematic approach to characterize rock masses at a 100-m scale. The approach uses detailed observations of pressure responses during drilling to map the conductive geometry of fracture networks. Once specific conductors are identified, tracer tests provide the transport properties of the pathways.
The Kamaishi mine is located in the northeastern part of Japan's main island. Honshu Figure 1 shows the location of the site and layout of the underground workings in the experiment area. The experiment used a borehole array north of the KD-90 drift at a depth about 350 meters below the surface. The geology of the mine includes metamorphic, iron-bearing formations and intrusive bodies of granodiorite. The experiment area is located in the middle of the Kurihashi granodiorite body.
The initial design of the testing program was driven by the dis- covery of "flow barrier" in a borehole, KH-19, that had been drilled to investigate the hydraulic boundary conditions for the experimental area.
