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Takayasu, Kentaro; Onuki, Kenji*; Kawamoto, Koji*; Takayama, Yusuke; Mikake, Shinichiro; Sato, Toshinori; Onoe, Hironori; Takeuchi, Ryuji
JAEA-Technology 2017-011, 61 Pages, 2017/06
The Groundwater REcovery Experiment in Tunnel (GREET) was put into effect as development of drift backfilling technologies. This test was conducted by making the Closure Test Drift (CTD) recovered with water after carrying out a plug around 40m distance from northern edge face of horizontal tunnel of depth 500m, for the purpose of investigation of recovering process of rock mass and groundwater under the influence of excavation of tunnel. This report presents the efforts of backfilling investigation using bentonite composite soil and execution of backfilling into borehole pits excavated in the CTD which were carried out in fiscal 2014 as a part of GREET, and succeeding observation results inside pits from September 2014 to March 2016.
Takeuchi, Ryuji; Iwatsuki, Teruki; Takayasu, Kentaro; Kawakubo, Masahiro*; Kobayashi, Masato*
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no abstracts in English
Onoe, Hironori; Takayasu, Kentaro; Hayashida, Kazuki; Takeuchi, Ryuji; Iwatsuki, Teruki
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Takayasu, Kentaro; Keya, Hiromichi; Onoe, Hironori; Takeuchi, Ryuji
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The reflood test which fills the part of the tunnel of depth 500m with groundwater is being put into effect for the purpose of exemplification of the recovery ability of the geological environment in the bedrock which was disturbed by construction and operation of large-scale underground facilities, and development of observation and evaluation technique of geological environment recovery at The Mizunami Underground Research Laboratory (MIU). Water pressure observation devices were installed in the tunnel and in each observation section in the surrounding bedrock, and groundwater pressure change in this test was observed. Similarity of water pressure change between the tunnel and each observation section was considered by arranging observed water pressure change data as derivative plots and focusing their shapes.
Beppu, Shinji; Onoe, Hironori; Kohashi, Akio; Ueno, Tetsuro; Takayasu, Kentaro; Takeuchi, Ryuji; Ishibashi, Masayuki; Sawada, Atsushi
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no abstracts in English
Onoe, Hironori; Takayasu, Kentaro; Hayashida, Kazuki; Takeuchi, Ryuji; Iwatsuki, Teruki
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Ozaki, Yusuke; Onoe, Hironori; Takayama, Yusuke; Takayasu, Kentaro; Takeuchi, Ryuji
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The purpose of this study is to identify factors that dominate the saturation in bentonite mixture material during drift closure test. The bentonite mixture buried in two pits in the test drift is monitored to evaluate its hydro-mechanical behavior during the test. To clear the factors effective to the saturation in the mixture, we perform numerical simulation focusing on the effect of swelling, hydraulic conductivity and unsaturated characteristics in the mixture. Our simulation results show that the unsaturated characteristics of the mixture have the greatest effect on the saturation in the mixture. For accurate estimation of saturation change in the mixture, unsaturated characteristics data is key information.
Takayasu, Kentaro; Takeuchi, Ryuji; Onoe, Hironori
no journal, ,
The Groundwater REcovery Experiment in Tunnel (GREET) is conducted by making the Closure Test Drift (CTD) recovered with water at the depth of 500m. Backfilling test is conducted as a part of GREET to acquire physical property change of the backfill material. Bentonite mixture was constructed into two pits excavated 1m in depth on the floor of the CTD. Hydraulic pressure, soil pressure and moisture content were measured to grasp the groundwater saturation process and the swelling process of backfill material. The moisture content in the pits got almost fully saturated till one month after. During water filling event, both hydraulic pressure and soil pressure reached 3.1 MPa at maximum. The swelling pressure of the backfill was calculated as 0.03-0.09 MPa. Observation inside the pit will be continued, and characteristics of backfill material will be investigated again. Changes of hydraulic pressure and soil pressure will be simulated and the construction method will be validated.
Keya, Hiromichi; Takayasu, Kentaro; Kohashi, Akio; Onoe, Hironori; Takeuchi, Ryuji
no journal, ,
no abstracts in English