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Goke, Mitsuo*; Horita, Masakuni*; Wakabayashi, Naruki*; Nakaya, Atsushi*
JNC TJ7400 2005-058, 167 Pages, 2005/03
JNC-TJ7400-2005-058.pdf:7.49MB
The purposes of this study were to contribute to both the evaluation of mechanical stability of a research drift and the plan of future studies. The crack tensor model based on mechanical property on the Toki granite at the Mizunami Underground Research Laboratory construction site was applied to analyze the rock stress as a research drift and a shaft were excavated. The virtual fracture model was applied to the hydraulic conductivity change analysis.The results are as follows:1)In the reference case of a shaft, convergence showed 9.03mm at the GL-500m, and 21.78mm at the GL-1000m. The maximum increase rate of hydraulic conductivity showed about 14 times at the both depth. In the reference case of a drift, convergence of a splingline showed 3.36mm at the GL-500m, and 7.99mm at the GL-1000m. The maximum increase rate of hydraulic conductivity showed a range of about 28 times from about 19 times at the GL-500m, and a range of about 45 times from about 15 times at the GL-1000m.2)As rock class getting weaker, the convergence of a shaft and a drift increased, also the stress in support parts increased, while distributions of the safety factor and the hydraulic conductivity change were almost changeless.3)As the direction of a drift changed to 90 degrees form 0 degrees, the convergence of a shaft and a drift increased, also the stress in support parts increased, and distributions of the safety factor and the hydraulic conductivity change were affected.4)As compared with analytical result regardless of excavation damaged zone, analytical result in consideration of excavation damaged zone showed that the convergence and the stress in support parts increased. Especially, the maximum increase rate of hydraulic conductivity increased remarkably. For example, the maximum increase rate of hydraulic conductivity was 240 times to 400 times at the bottom of a drift
Goke, Mitsuo*; Tada, Hiroyuki*; Horita, Masakuni*; Wakabayashi, Naruki*
JNC TJ7400 2003-003, 93 Pages, 2003/02
JNC-TJ7400-2003-003.pdf:5.87MB
Tono Geoscience Center (TGC), Japan Nuclear Cycle Development Institute (JNC) conducts the Mizunami Undergroud Research Laboratory (MIU) project in order to develop the comprehensive investigation techniques for the geological environment and the engineering techniques in the deep underground application. The purposes of this study were to contribute to the construction of rock mechanical modeling for MIU project. The virtual fracture model based on mechanical property on the Toki granite was applied to the 2-D hydraulic conductivity change analysis in excavating a research drift and a shaft. The crack tensor analysis model was introduced to the stress analysis before the hydraulic conductivity change analysis. The results are as follows: (1) The crack tensor stress analysis showed very small displacement on the perimeter of a shaft and a drift in intact rock mass, while large displacement appeared in fault zone. (2) More than 10 times large hydraulic conductivity from the initial one appeared in the extent of 1m from the perimeter of a drift and a shaft, in the hydraulic conductivity change analysis with the virtual fracture model for the intact rock mass. The maximum increase of hydraulic conductivity was up to 100 times from initial one. The fault zone showed more than 10 times larger hydraulic conductivity in the extent of 4m from the perimeter. (3) The extent of hydraulic conductivity change was affected by the direction of a drift due to the direction of fractures and the initial stress condition. For example, the rate of hydraulic conductivity increased from initial one changed 110 times to 670 times with the direction of a drift, at the side wall of a drift at the depth of 945m. (4) There was no clear effect to reduce the displacement by supports in the drift in intact rock mass.
Ara, Hiroshige*; Fukumitsu, Kenji*; Iizuka, Yunosuke*; Ishii, Takashi*; Izumiya, Yasushi*; Imazu, Masanori*; Utsugida, Yoshizo*; Hasegawa, Makoto*; Maeda, Masaya*; Yabe, Yukio*; et al.
PNC TJ199 84-04VOL1, 20 Pages, 1984/03
PNC-TJ199-84-04VOL1.pdf:0.88MB
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