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Sanada, Masanori; Kishi, Hirokazu*; Sugita, Yutaka; Hayashi, Katsuhiko*; Takebe, Atsuji*; Okubo, Seisuke*
JAEA-Research 2012-025, 130 Pages, 2012/09
JAEA-Research-2012-025.pdf:4.12MB
In this study, strength recovery, generalized stress relaxation and two tensile strength tests were carried out using shale sampled in the Wakkanai-formation. As the results, by using the value of a suitable constant with the constitutive equation showing strength recovery, it was showed that change of the axial stress in a compacting test could be expressed. About the generalized relaxation, it examined by the air dried and the saturated condition. Visco-elastic behavior was more remarkable in saturated condition than the air dried. Moreover, when the loading rate up to the starting point of the generalized relaxation test was large, the influence on visco-elastic behavior was remarkable. About tensile characteristics, a splitting tensile strength test and a uniaxial tensile strength test were carried out. About splitting tensile strength, it turned out that the influence of the loading direction on a bedding plane is great.
Sanada, Masanori; Kishi, Hirokazu; Hayashi, Katsuhiko*; Takebe, Atsuji*
JAEA-Research 2011-055, 79 Pages, 2012/03
JAEA-Research-2011-055.pdf:4.11MB
In order to refine and rationalize a design method of multi tunnels in the deep geological repository, various study have been conducted. In this study, an effect of procedure for excavating multi-tunnels on extent of EDZ was examined by 3D FEM analysis. In modeling the multi tunnels and setting cases of analysis, workability, cost and safeness under construction were considered. Results of 3D FEM analysis showed that 3D effect of procedure for excavating such as a gap of progress with tunnel faces can be considered by 3D FEM and extent of EDZ is demonstrated more practically compared with 2D FEM. Another 2D FEM analysis modeling for crystalline rock (granite) was executed and the results showed that plastic zone did not appear in all cases.
Sanada, Masanori; Hayashi, Katsuhiko*; Kishi, Hirokazu; Takebe, Atsuji*; Okubo, Seisuke*
JAEA-Research 2011-028, 102 Pages, 2011/11
JAEA-Research-2011-028.pdf:3.08MB
In this study, strength recovery, generalized stress relaxation and two tensile strength tests were carried out using shale sampled in the Wakkanai-formation. As the results, recovery of failed rocks in strength and hydraulic conductivity were observed under a certain condition. We believe this result is very important for the stability evaluation of underground space in the bedrock that needs good sealing up characteristic, isolation characteristic, safety and high reliability for long term. Generalized stress relaxation test was conducted submerging samples in water. Experimental results showed comparatively smaller scatter than those in air-dried condition. It was also found that testing results were affected by strain rate up to the starting point of generalized relaxation test. Indirect and uniaxial tensile strength tests were also conducted submerging samples in water and smaller tensile strength with smaller scatter were obtained than those in air-dried condition.
Hayashi, Katsuhiko; Kishi, Hirokazu; Kabayashi, Yasushi*; Takebe, Atsuji*; Fujiyama, Tetsuo*; Hiramoto, Masayuki*; Mizutani, Kazuhiko*; Morita, Atsushi*
JAEA-Research 2010-059, 92 Pages, 2011/03
JAEA-Research-2010-059.pdf:3.71MB
In this study, the first investigation is the order of the multi-tunnels excavation. The second is the strain-softening model for multi-tunnels which is based on test data at Horonobe site. As results of first investigation, we showed as 2 dimensional analyses that it was desirable to excavate the tunnel of the remote distance at first and excavate the tunnel between these tunnels next, and it is necessary for the examination that reflected a real plan, such as evacuation machine and actual multi tunnel layout. As the results of second investigation, we also showed the more reliable EDZ by using the strain-softening model that is based on test data at Horonobe site. Furthermore, we standardized the design method (draft) for the practical use by referring the past studies of multi tunnel design method.
Hayashi, Katsuhiko; Kishi, Hirokazu; Kabayashi, Yasushi*; Takebe, Atsuji*; Okubo, Seisuke*
JAEA-Research 2009-058, 106 Pages, 2010/02
JAEA-Research-2009-058.pdf:18.82MB
In this study, experimental studies on the strength recovery, the generalized stress relaxation behavior and the tensile strength were conducted using samples obtained from the Wakkanai-formation shale. As the results, the strength recovery has time-dependent characteristics. It was founded that the generalized stress relaxation behavior depends on the draining conditions. Furthermore, regarding the tensile strength, complete stress-strain curve under uniaxial tensile strength conditions was gotten and it was found that there is small residual strength. The results of uniaxial tensile strength in this year are almost same as the minimum value of splitting tensile strength test results.
Hayashi, Katsuhiko; Kishi, Hirokazu; Kabayashi, Yasushi*; Takebe, Atsuji*; Fujiyama, Tetsuo*; Hiramoto, Masayuki*; Mizutani, Kazuhiko*; Morita, Atsushi*
JAEA-Research 2009-056, 86 Pages, 2010/02
JAEA-Research-2009-056.pdf:9.96MB
In this study, the effect of constitutive models such as strain softening of rock masses for EDZ, and the stress relief ratio used for multi tunnels analysis were conducted. As the result, it is necessary to confirm mechanical behavior of in situ rock and it is important to choose suitable constitutive models, and it is possible for all tunnels in multi tunnels model to have same stress relief ratio.
Xiao, J.; Sato, Hisashi*; Sawada, Atsushi; Takebe, Atsuji*
Proceedings of 4th Asian Rock Mechanics Symposium (ARMS 2006) (CD-ROM), 8 Pages, 2006/11
The heterogeneous void geometries (aperture distribution) in a single fracture have a strong influence on fluid flow process and the solute transport. In order to understand and to predict flow and transport phenomenon through fracture, this paper describes newly developed method for the simultaneous evaluations of fracture aperture, concentration distribution of tracers and fluid velocity in a fracture by means of Light-emitting diode (LED) transmission measurement and Particle Image Velocity (PIV) combine system. It was utilized to accomplish the visualization of flow and solute transport, and to evaluate quantitatively the effect of fracture aperture correlation on temporal flow and transport process through fracture.
Sato, Akira*; Fukahori, Daisuke*; Sugawara, Katsuhiko*; Sawada, Atsushi; Takebe, Atsuji*
Advances in X-ray Tomography for Geomaterials, p.315 - 321, 2006/09
The two dimensional (2D) diffusion tests with the rock sample which has single plane crack were conducted, and the diffusion of non-sorbing tracer from the crack to rock matrix is visualized by X-ray CT in this study. It was found that the increment of CT value due to the 2D diffusion of the dense tracer from crack surface to the matrix of rock sample was observed. It was also found that the application of image processing techniques makes it possible to obtain the clear image data and that the precious analysis of diffusion phenomena becomes possible. The numerical simulation was also conducted in order to verify the experimental results. The results of 2D diffusion tests show good agreement with the numerical results, and the applicability of X-ray CT to the analysis of diffusion phenomena in a rock sample was verified together with the necessary image processing techniques.
Maekawa, Keisuke; Sawada, Atsushi; Hara, Akio; Takebe, Atsuji; Makino, Hitoshi; Wakasugi, Keiichiro; Kato, Tomoko; Ebashi, Takeshi; Shibata, Katsushi*
Hoshasei Haikibutsu Anzen Kenkyu Nenji Keikaku (Heisei-13-Nendo
Heisei-17-Nendo) Kenkyu Seika Hokokushu, p.117 - 129, 2006/03
no abstracts in English
Takebe, Atsuji; Sawada, Atsushi; Uchida, Masahiro; Yamamoto, Asao*; Hosoda, Atsushi*
Doboku Gakkai Dai-60-Kai Nenji Gakujutsu Koenkai Koen Gaiyoshu, p.657 - 658, 2005/09
Focusing on the cover layer materials (as the Radon Barrier Materials), which could have the effect to restrain the radon from scattering into the air and the effect of the radiation shielding, we produced the radon barrier materials with crude bentonite on an experimental basis, using the rotary type comprehensive unit for grinding and mixing, through which we carried out the evaluation of the characteristics thereof.
Sato, Hisashi*; Takebe, Atsuji
JNC TN8410 2005-003, 32 Pages, 2005/04
JNC-TN8410-2005-003.pdf:23.63MB
In case of measuring tracer concentration using an electrical conductivity meter, tracer residence time will be overestimated due to the relative larger volume at electrical conductivity meter and tubing from fracture to electrical conductivity meter. When using a small rock fracture sample, it is difficult to conduct tracer tests with sufficient accuracy. Because capacity in a crack is small, influence of dead volume is large. Then, authors devised the tracer pouring method of not being influenced of dead volume. In order to check the performance of the tracer pouring method, the parallel plate with a crack width of 10cm and a crack length of 10cm made from acrylics was used, and permeability tests, tracer tests, and measurement of geometric aperture were conducted. Consequently, it was continued that a tracer tests could be conducted under sufficient accuracy by our method.
Nishiyama, Satoshi*; Uehara, Shinichi*; Yano, Takao*; Saito, Ryuhei*; Uchida, Masahiro; Sawada, Atsushi; Takebe, Atsuji
JNC TY8400 2005-007, 70 Pages, 2005/03
JNC-TY8400-2005-007.pdf:2.24MB
None
Sato, Akira*; Uchida, Masahiro; Sawada, Atsushi; Takebe, Atsuji; Sato, Hisashi*
JNC TY8400 2005-001, 47 Pages, 2005/03
None
Sato, Akira*; Fukahori, Daisuke*; Sugawara, Katsuhiko*; Sawada, Atsushi; Takebe, Atsuji
no journal, ,
no abstracts in English
Takebe, Atsuji; Sakamoto, Kazuhiko*; Sawada, Atsushi
no journal, ,
no abstracts in English
Sawada, Atsushi; Takebe, Atsuji*; Sakamoto, Kazuhiko*
no journal, ,
Quantitative evaluation of the groundwater velocity in the fractures is a key part of contaminants transport assessment especially in the radioactive waste disposal programs. In a hydrogeological model such as the discrete fracture network model, transport aperture of water conducting fracture is one of the important parameter for evaluating groundwater velocity. To study relationship between transport aperture, hydraulic aperture and transmissivity, numerical simulations were conducted by using a single fracture model with a heterogeneous aperture distribution. The results show that the mean geometrical aperture is the most sensitive parameter among the three variable parameters in this study. It is also found that the contact area ratio affects transmissivity more than the JRC, Joint Roughness Coefficient, and while the JRC strongly affects the velocity and transport aperture.
Hayashi, Katsuhiko; Kishi, Hirokazu; Takebe, Atsuji*
no journal, ,
The geological disposal facility for high-level radioactive waste has the new structure that consists of many tunnels in parallel (multi tunnels). Our organization designed this facility by using single tunnel model at the beginning, however we realized that this method can not predict where is Excavation disturbed zone that is caused by excavation as multi tunnels characteristics. Now we are investigating the new design methodology with multi tunnel models that takes into account of their behavior for improving design accuracy.
Hayashi, Katsuhiko; Kishi, Hirokazu; Takebe, Atsuji*
no journal, ,
The geological disposal facility for high-level radioactive waste has the new structure that consists of many tunnels in parallel (multi tunnels) at 300 m under the ground. Our organization designed this facility by using single tunnel model at the beginning, however we realized that this method can not predict where is excavation disturbed zone that is caused by excavation as multi tunnels characteristics. Now we are investigating the new design methodology with multi tunnel models that takes into account of their behavior for improving design accuracy.