An Overview of a full-scale construction experiment for the tunnel sealing technology at Horonobe URL

木村 駿  ; 早野 明  ; 小野 誠*

Kimura, Shun; Hayano, Akira; Ono, Makoto*

Excavation damaged zone (EDZ), resulting from tunneling and stress redistribution, has the potential to increase hydraulic conductivity by creating new fractures and opening existing ones, and to act as a short-circuit flow path between the repository and ground surface. In the closure phase of the repository for geological disposal in Japan, the backfilling of tunnels and the installation of hydraulic plugs are considered in order to provide the safety function of reducing radionuclide migration by avoiding flow short-circuits through and around the tunnels. Japan Atomic Energy Agency initiated a full-scale construction experiment at Horonobe URL. The objective of this experiment is to develop and demonstrate the design and construction technology of the hydraulic plug for sedimentary rock. The experiment is concerned with the characterization of EDZ in relation to its mechanical and hydraulic properties, the material design of the tunnel backfill and hydraulic plug, and the development of the construction technology. This report represents the consideration of the hydraulic plug shape employing three-dimensional analysis of the excavation of the tunnel and notch.