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JAEA Reports

Improvement in Reliability of the Long-Term Mechanical Behavior of Buffer Material

Takaji, Kazuhiko*; Shigeno, Yoshimasa*; Shimogochi, Takafumi*; Hirai, Takashi*; Shiratake, Toshikazu*

JNC TJ8440 2004-011, 200 Pages, 2005/02

JNC-TJ8440-2004-011.pdf:5.05MB

On the R&D of the high-level radioactive waste repository, it is essential that Engineered Barrier System (EBS) is stable mechanically over along period of time for maintaining each ability required to EBS. After closing the repository, the various external forces will be affected to buffer intricately for along period of time. So, to make clear the mechanical deformation behavior of buffer against the external force is important, because of carrying out safety assessment of EBS accurately. In this report, several sets of parameters are chosen for the previously selected two constitutive models, Sekiguchi-Ohta model and Adachi-Oka model, and the element tests and mock-up tests are simulated using these parameters. Through the simulation, applicability of the constitutive models and parameters is examined. Moreover, simulation analyses of EBS using these parameters were carried out, and mechanical behavior is evaluated over a long period of time. Analysis estimated the amount of settlement of the over pack, the stress state of buffer material, the reaction force to a base rock, etc., and the result that EBS is mechanically stable over a long period of time was obtained. Next, in order to prove analyses results a side, literature survey was conducted about geological age, the dynamics history of a Smectite layer. The outline plan was drawn up about the natural analogue verification method and preliminary examination was performed about the applicability of

JAEA Reports

Research on mechanical characteristic of the bentonite mixture material under the groundwater environment of Horonobe(II)

Takaji, Kazuhiko*; Shigeno, Yoshimasa*; Shimogochi, Takafumi*

JNC TJ5400 2004-002, 89 Pages, 2005/02

JNC-TJ5400-2004-002.pdf:12.07MB

None

JAEA Reports

Research on the mechanical characteristic of the bentonite mixture material under the groundwater environment of Horonobe

Takaji, Kazuhiko*; Shigeno, Yoshimasa*; Shimogochi, Takafumi*

JNC TJ5400 2003-007, 120 Pages, 2004/04

JNC-TJ5400-2003-007.pdf:1.76MB

In the Horonobe underground research project, a creep examination of a rock and buffer material, a tunnel closing examination, a fixed accuracy confirmation examination and a T-H-M-C examination, etc. is planned. These field examinations are aimed at the illustration and evaluation of applicability of the Engineered Barrier System (EBS) design method under the detailed geological environment shown in the H12 report, understanding of long-term phenomenon for EBS, and improvement in reliability of the prediction method. Then, in order to examine the specifications of the bentonite mixture material in design of a field test, the in-situ examination using artificial groundwater which imitated the groundwater of Horonobe and NaCl solution was carried out, and the mechanical behavior of the bentonite mixture material under the sea water environment assumed in the location of the field examination in Horonobe has been grasped. Moreover, in order to confirm the applicability of the prediction technique of the long-term behavior of an engineered barrier, overpack sinking behavior using the result of an in-situ examination etc. was analyzed.

JAEA Reports

Examination of Constitutive Model for Evaluating Long-Term Mechanical Behavior of Buffer(III)

Takaji, Kazuhiko*; Shigeno, Yoshimasa*; Shimogochi, Takafumi*; Shiratake, Toshikazu*; Tamura, Hirokuni*

JNC TJ8440 2003-007, 218 Pages, 2004/02

JNC-TJ8440-2003-007.pdf:4.43MB

On the R. and D. of the high-level radioactive waste repository, it is essential that Engineered Barrier System (EBS) is stable mechanically over a long period of time for maintaining each ability required to EBS. After closing the repository, the various external forces will be affected to buffer intricately for a long period of time. So, to make clear the mechanical deformation behavior of buffer against the external force is important, because of carrying out safety assessment of EBS accurately.In this report, several sets of parameters are chosen for the previously selected two constitutive models, Sekiguchi-Ohta model and Adachi-Oka model, and the element tests and mock-up tests are simulated using these parameters. Through the simulation, applicability of the constitutive models and parameters is examined.Moreover, simulation analyses of EBS using these parameters were carried out, and mechanical behavior is evaluated over a long period of time. Analysis estimated the amount of settlement of the over pack, the stress state of buffer material, the reaction force to a base rock, etc., and the result that EBS is mechanically stable over a long period of time was obtained. Next, in order to prove analyses results a side, literature survey was conducted about geological age , the dynamics history of a Smectite layer.The outline plan was drawn up about the natural analogue verification method and preliminary examination was performed about the applicability of "Freezing Sampling".

JAEA Reports