In-situ backfilling experiment of the small scall drift by spray method in Mizunami Underground Research Laboratory, Japan

Matsui, Hiroya; Yahagi, Ryoji*; Ishizuka, Hikaru*; Toguri, Satohito*

WIT Transactions on Ecology and the Environment, Vol.247, p.145 - 159, 2020/00

https://doi.org/10.2495/WM200141

In situ backfilling experiment using spray method in the small scale drift (approximately 4 by 3 m scale) was conducted at 500 m depth in Mizunami Underground Research Laboratory (MIU) established by JAEA (Japan Atomic Energy Agency). The backfill material consists of sand and bentonite. Specification for the backfill material was designed to satisfy the target permeability of generic host rock (10 m/sec) assumed by NUMO. In this case, effective clay density should be 0.4 Mg/m or more. Quality control of the material before backfilling was performed by setting the initial water contents (average 14%) based on the results of the laboratory testing and preliminary spray testing on ground surface. Densities of the backfilled material measured at any points satisfied the specification and the results suggested the establishment of the practical quality control methodology of the backfilling by spray method under actual deep geological environment. The in situ experiment was sponsored by METI (Ministry of Environment, Trade and Industry).

Study on engineering technologies in the Mizunami Underground Research Laboratory (FY 2015); Development of design and construction planning and countermeasure technologies (Contract research)

Toguri, Satohito*; Kobayashi, Shinji*; Tsuji, Masakuni*; Yahagi, Ryoji*; Yamada, Toshiko*; Matsui, Hiroya; Sato, Toshinori; Mikake, Shinichiro; Aoyagi, Yoshiaki

JAEA-Technology 2017-005, 43 Pages, 2017/03

JAEA-Technology-2017-005.pdf:4.4MB

The study on engineering technology in the Mizunami Underground Research Laboratory (MIU) project roughly consists of (1) development of design and construction planning technologies, (2) development of construction technology, (3) development of countermeasure technology, (4) development of technology for security, and (5) development of technologies regarding restoration and mitigating of the excavation effect. In FY2015, as a part of the important issues on the research program, water-tight grouting method has been developed. Grouting methods utilized in the MIU were evaluated and the post-excavation grouting at the -500m Access/Research Gallery-South was planned based on these evaluation results. Also, technology development from the viewpoint of geological disposal was summarized, and information on the alternative method to the grouting method was collected and organized.

Analysis of excavation cycle time during sinking of the ventilation shaft at the Mizunami Underground Research Laboratory

Sanada, Hiroyuki; Sato, Toshinori; Horiuchi, Yasuharu*; Mikake, Shinichiro; Okihara, Mitsunobu*; Yahagi, Ryoji*; Kobayashi, Shinji*

Proceedings of 8th Asian Rock Mechanics Symposium (ARMS-8) (USB Flash Drive), 7 Pages, 2014/10

The Japan Atomic Energy Agency (JAEA) is implementing the Mizunami Underground Research Laboratory (MIU) Project to establish the scientific and technological basis for the geological disposal of High-level Radioactive Waste (HLW) in crystalline rocks. Excavation cycle times were recorded during the Ventilation Shaft sinking and compared with the planned excavation cycle times for evaluation of the baseline design plan. This included review of the cycle times in the design process and comparison with the actual construction results. The recorded results indicate that actual cycle times were twice as long as the design plan. This paper describes discussions on differences in cycle times between the design and result.

Pre-grouting to reduce water inflow in the ventilation shaft into the Mizunami Underground Research Laboratory

Hara, Masato; Kinoshita, Harunobu; Ikeda, Koki; Yamamoto, Masaru; Yahagi, Ryoji*; Kikuchi, Shinji*; Kawano, Hiromichi*; Ushida, Kazuhito*; Nobuto, Jun*; Minamide, Masashi*

no journal, , 

At the Mizunami Underground Research Laboratory, inflow water control to inside the tunnel has become topic. Because of this, the pre-grouting at inside the tunnnel of depth 200m was executed. In this report, it is something which is reported concerning the result of the pre-grouting.

Planning for in-situ backfilling test to the gallery in the Mizunami Underground Research Laboratory

Matsui, Hiroya; Yahagi, Ryoji*; Okihara, Mitsunobu*; Toguri, Satohito*

no journal, , 

This report describes the overall plan of in-situ test to backfill a part of Mizunami Underground Research Laboratory, which is planned for development of tunnel backfilling method.

In-situ experiment for the backfilling in a small scale drift by spray method, 2; The Results of in-situ experiment in MIU

Ishizuka, Hikaru*; Yahagi, Ryoji*; Toguri, Satohito*; Matsui, Hiroya

no journal, , 

This repot summarize about the results of the in-situ experiment for the backfilling in MIU by spray method funded by METI.