Monitoring of pore water pressure and groundwater chemistry at MSB-2 and MSB-4 boreholes in the MIU construction site; April, 2009 - March, 2010

Hagiwara, Hiroki; Sai, Masataka*; Takeguchi, Masato*; Horita, Masakuni*; Mizuno, Takashi

JAEA-Data/Code 2010-032, 35 Pages, 2011/03

JAEA-Data-Code-2010-032.pdf:1.8MB

Japan Atomic Energy Agency (JAEA) has been carried out investigation to understand the variation of groundwater chemistry related to the shafts construction of Mizunami Underground Research Laboratory (MIU) at Mizunami City, Gifu prefecture, Japan. This report aimed to compile the data of pore water pressure and groundwater chemistry obtained from surface based boreholes, MSB-2 and MSB-4 boreholes with installed continuous monitoring equipment for multi-interval water pressure (MP system, made by westbay company) between the April 2009 and March 2010. Groundwater sampling and measurement of pore water pressure were conducted once in a month. As the result, we could obtain the data of pore water pressure and groundwater chemistry continuously from 2003 and understand their variation related to the shafts construction in 2009.

Monitoring of pore water pressure and groundwater chemistry at MSB-2 and MSB-4 boreholes; April, 2007 - March, 2008

Sai, Masataka; Hagiwara, Hiroki; Takeguchi, Naoto*; Yasue, Motoi*; Horita, Masakuni*; Mizuno, Takashi

JAEA-Data/Code 2010-007, 191 Pages, 2010/06

JAEA-Data-Code-2010-007.pdf:2.79MB

Japan Atomic Energy Agency (JAEA) has been carried out investigation to understand the variation of groundwater chemistry related to the construction of Mizunami Underground Research Laboratory (MIU) at Mizunami City, Gifu prefecture, Japan. This report compiles the summarized data set of pore water pressure and groundwater chemistry at MSB-2 and MSB-4 boreholes in the MIU construction site since April, 2007 to March, 2008.

Excavation disturbance analysis based on crack tensor model and virtual fracture model for research drift of the Mizunami Underground Research Laboratory

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

Drift excavation analysis based on crack tensor model and virtual fracture model in consideration of excavation damaged zone

Goke, Mitsuo*; Horita, Masakuni*; Tada, Hiroyuki*

JNC TJ7400 2004-007, 102 Pages, 2004/02

JNC-TJ7400-2004-007.pdf:4.85MB

Tono Geoscience Center (TGC), Japan Nuclear Cycle Development Institute (JNC) conducts the Mizunami Underground 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 work were to contribute to the rock mechanical modeling for MIU project. We proposed an analytical method of modeling of excavation damaged zone. The crack tensor analytical model was applied to analyze the rock stress in consideration of the existence of excavation damaged zone 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) As compared with analytical result without excavation damaged zone, the crack tensor stress analysis in consideration of excavation damaged zone showed that the convergence of a shaft and a drift increased and the maximum value of principal stress decreased, while the safety factor distribution was almost changeless.2) As compared with analytical result without excavation damaged zone, the hydraulic conductivity change analysis in consideration of excavation damaged zone showed the maximum increase rate of hydraulic conductivity increased remarkably.3) As the stiffness decreased in excavation damaged zone, the convergence of a shaft and a drift increased, the maximum value of principal stress decreased, and the maximum increase rate of hydraulic conductivity increased. Especially, in analytical case supposed that new cracks parallel to perimeter of a drift broke out in excavation damaged zone, the maximum increase rate of hydraulic conductivity was up to 5000 times.4) As the stiffness of rock mass decreased by taking into the existence of excavation damaged zone, the convergence reduction effect increased, and the stress in support parts increased.

Installation of Groundwater Pressure Probes in HDB-1 for Continuous Monitoring

Horita, Masakuni*; Muroi, Tatsumi*

JNC TJ5410 2004-005, 27 Pages, 2003/08

JNC-TJ5410-2004-005.pdf:11.34MB

This contract is involved in the purchase and the installation of data-logging system for the borehole, HDB-1. This contract contains the following works in the borehole, HDB-1; 1) puchase of 4 pressure probes and a data logger, 2) installation of the 4 pressure probes in HDB-1 at the depth of 448.85m, 560.80m, 597.15m, 65085m each,3) data-logging of these probes and atmospheric pressure from August 4,2003 to August 5, and 4) setting the data logging schedule for the following monitoring.

Hydraulic Conductivity Change Analysis of Surrounding Rock Mass in Excavating Research 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.

Investigations on repository layouts

Tanai, Kenji; Iwasa, Kengo; Hasegawa, Hiroshi; Goke, Mitsuo*; Horita, Masakuni*; Noda, Masaru*

JNC TN8400 99-044, 140 Pages, 1999/11

JNC-TN8400-99-044.pdf:7.85MB

This report consists of three items: (1)Study of the repository configuration, (2)Study of the surface facilities configuration for construction, operation and buckfilling, (3)Planning schedule, In the repository configuration, the basic factors influencing the design of the repository configuration are presented, and the results of studies of various possible repository configurations are presented for both hard and soft rock systems. Here, the minimum conditions regarding geological environment required to guide design are assumed, because it is difficult to determine the repository configuration without considering specific conditions of a disposal site. In the surface facility configuration, it is illustrated based on the results of construction, operation, buckfilling studies for underground disposal facility and EIS report of CANADA. In the schedule, the overall schedule corresponding to the repository layout is outlined in link with the milestone of disposal schedule set forth in the government's basic policy. The assumptions and the basic conditions are summarized to examine the General Schedule from start of construction to closure of a repository. This summaly is based on the technologies to be used for construction, operation and closure of a repository. The basic national policies form the framework for this review of the general schedule.

Study on Evaluation of Excavation Disturbed Zone at kamaishi Mine in 1996

Horita, Masakuni*; Kinoshita, Naoto*; Yoshioka, Naoya*; Tsuchihara, H.*

JNC TJ7400 2005-014, 424 Pages, 1997/03

In this study, the excavation disturbed zone (EDZ) in deep rock is evaluated in the 250m-level drift st the Kamaishi Mine for the kamaishi In-situ Test Project, Phase II.

Study regarding evaluation of underground water flow in wide area (4)

Shimo, Michito*; Horita, Masakuni*; Sudo, Ken*; Hibiya, Keisuke*; Yasuno, Masamitsu*

PNC TJ1449 92-007, 255 Pages, 1992/02

PNC-TJ1449-92-007.pdf:6.71MB

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