scholarly journals ESTIMATION OF GROUNDWATER FLOW AT THE SITE OF MIZUNAMI UNDERGROUND RESEARCH LABORATORY BY THE INVERSION OF SURFACE TILT DURING DRAINAGE, SUBMERGENCE AND RE-DRAINAGE IN EXCAVATION OF SHAFTS

2009 ◽  
Vol 65 (2) ◽  
pp. 442-455 ◽  
Author(s):  
Tatsuya NARIKAWA ◽  
Koji MATSUKI ◽  
Takashi ARAI ◽  
Takuya OHYAMA ◽  
Ryuji TAKEUCHI ◽  
...  
Keyword(s):  
Groundwater Flow ◽  
Research Laboratory ◽  
Underground Research Laboratory

Technical Know-How for Modeling of Geological Environment: Part 1—Overview and Groundwater Flow Modeling

2010 ◽  
Author(s):  
Hiromitsu Saegusa ◽  
Shinji Takeuchi ◽  
Keisuke Maekawa ◽  
Hideaki Osawa ◽  
Takeshi Semba
Keyword(s):  
Decision Making ◽  
Research And Development ◽  
Groundwater Flow ◽  
Research Laboratory ◽  
Site Characterization ◽  
Decision Making Process ◽  
Geological Environment ◽  
Flow Modeling ◽  
Know How ◽  
Underground Research Laboratory

It is important for site characterization projects to manage the decision-making process with transparency and traceability and to transfer the technical know-how accumulated during the research and development to the implementing phase and to future generations. The modeling for a geological environment is to be used to synthesize investigation results. Evaluation of the impact of uncertainties in the model is important to identify and prioritize key issues for further investigations. Therefore, a plan for site characterization should be made based on the results of the modeling. The aim of this study is to support for the planning of initial surface-based site characterization based on the technical know-how accumulated from the Mizunami Underground Research Laboratory Project and the Horonobe Underground Research Laboratory Project. These projects are broad scientific studies of the deep geological environment that are a basis for research and development for the geological disposal of high-level radioactive wastes. In this study, the work-flow of the groundwater flow modeling, which is one of the geological environment models, and is to be used for setting the area for the geological environment modeling and for groundwater flow characterization, and the related decision-making process using literature data have been summarized.

Low Alkaline Cement Used in the Construction of a Gallery in the Horonobe Underground Research Laboratory

2010 ◽  
Author(s):  
Masashi Nakayama ◽  
Haruo Sato ◽  
Yutaka Sugita ◽  
Seiji Ito ◽  
Masashi Minamide ◽  
...  
Keyword(s):  
Fly Ash ◽  
Research Laboratory ◽  
Concrete Lining ◽  
Energy Agency ◽  
Tunnel Support ◽  
Long Term Stability ◽  
Alkaline Conditions ◽  
High Level ◽  
Underground Research Laboratory

In Japan, any high level radioactive waste (HLW) repository is to be constructed at over 300 m depth below surface. Tunnel support is used for safety during the construction and operation, and shotcrete and concrete lining are used as the tunnel support. Concrete is a composite material comprised of aggregate, cement and various admixtures. Low alkaline cement has been developed for the long term stability of the barrier systems whose performance could be negatively affected by highly alkaline conditions arising due to cement used in a repository. Japan Atomic Energy Agency (JAEA) has developed a low alkaline cement, named as HFSC (Highly Fly-ash Contained Silicafume Cement), containing over 60 wt% of silica-fume (SF) and fly-ash (FA). HFSC was used experimentally as the shotcrete material in construction of part of the 140m deep gallery in the Horonobe Underground Research Laboratory (URL). The objective of this experiment was to assess the performance of HFSC shotcrete in terms of mechanics, workability, durability, and so on. HFSC used in this experiment is composed of 40 wt% OPC (Ordinary Portland Cement), 20 wt% SF, and 40 wt% FA. This composition was determined based on mechanical testing of various mixes of the above components. Because of the low OPC content, the strength of HFSC tends to be lower than that of OPC. The total length of tunnel using HFSC shotcrete is about 73 m and about 500 m3 of HFSC was used. The workability of HFSC shotcrete was confirmed in this experimental construction.

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