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JAEA Reports

Development of mechanical coupled analysis technique for the long term behavior of the near field, 2

Saito, Yuya; Tanai, Kenji; Takaji, Kazuhiko*; Shigeno, Yoshimasa*; Shimogochi, Takafumi*

JAEA-Research 2009-065, 76 Pages, 2010/03

JAEA-Research-2009-065.pdf:23.92MB

The 3-D mechanical coupled analysis technique for the long term mechanical behavior of near field is developed. The object of analysis is extended to the disposal gallery and the near field rock, in addition to the buffer material and the overpack for previous one. The analysis model is developed with a degradation model of concrete support and modeling of the near field rock with the valuable- compliance-type constitutive equation. The remaining problems of current study are related to; (1) mechanical property and modeling of backfill material, (2) adopting a degradation model of concrete support in the prototype model, (3) examining the effect of analytical model mesh and time step for the 3-D mechanical coupled analysis. We conducted the one-dimensional consolidation test for the backfill material. The backfill material shows a similar behavior to that of buffer material. And the prototype model is developed adopting a degradation model for a concrete support and examining the effect of the model mesh and time step.

JAEA Reports

Development of mechanical coupled analysis technique for the long term behavior of the near field

Nishimura, Mayuka; Tanai, Kenji; Takaji, Kazuhiko*; Shigeno, Yoshimasa*; Shimogochi, Takafumi*

JAEA-Research 2007-004, 87 Pages, 2007/03

JAEA-Research-2007-004.pdf:14.61MB

The 3-D mechanical coupled analysis technique for the near field is developed, upgrading a 2-D non-coupled technique for the buffer material. The analysis object is extended to the disposal gallery and the near field rock, in addition to the EBS. And following problems are approached; (1) modeling the near field rock with the valuable- compliance-type constitutive equation, (2) modeling a degraded behavior of the concrete support, (3) changing the expanding deform method of the overpack corrosion, (4) examining the effect of drainage conditions on water pressure behavior of the near field rock, (5) setting parameters of the backfill material modeled with Sekiguchi-Ohta model. The prototype model is developed adopting the result for the above approaches, excluding a degradation model of concrete support. The result of long term analysis with the prototype model shows a reasonable behavior of the near field that reflects the models of the near field rock and the backfill material.

JAEA Reports

A Study on finding suitable parameters for constitutive models of evaluating long term mechanical behavior of buffer material

Nishimura, Mayuka; Tanai, Kenji; Takaji, Kazuhiko*; Hirai, Takashi*; Shiratake, Toshikazu*

JAEA-Research 2006-036, 82 Pages, 2006/06

JAEA-Research-2006-036.pdf:4.09MB

In order to evaluate the long term mechanical behavior of the Enginnered Barrier System (EBS), it is essential to set suitable parameters of constitutive models of the buffer material. In this report, the parameters of the Sekiguchi-Ohta model and the Adachi-Oka model are examined. The results are as follows; it is impossible to set the sole parameter which can evaluate both the deformation and the stress of the buffer material. But when selecting a suitable parameter for the object of evaluation, the mechanical behavior of buffer material can be approximately described. On the other hand, the range of the secondary consolidation coefficient of the bentonite ore is estimated to corroborate to the viscous parameter of the buffer material, using a natural analogue study. Finally, the mechanical behavior of the buffer material is analyzed using these parameters, and the maximum amount of settling of the overpack is estimated.

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, 100 Pages, 2005/02

JNC-TJ5400-2004-002.pdf:9.74MB

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

Study on Proper Constitutive Model for Evaluation of Long Term Mechanical Behavior of Buffer Material

Hirai, Takashi; Tanai, Kenji; Kikuchi, Hirohito*; Shigeno, Yoshimasa*; Namikawa, Tsutomu*; Takaji, Kazuhiko*; Onuma, Satoshi*

JNC TN8400 2003-034, 158 Pages, 2004/02

JNC-TN8400-2003-034.pdf:5.26MB

The objective of this report is to make a proposal of the proper constitutive models and parameters for the evaluation of the long term mechanical behavior of the buffer material in the engineered barrier system. In the second progress report by JNC, it was reported that the well designed engineered barrier system is stable and safety on mechanical support of the overpack to ensure stability and stress which acts on the overpack by using analysis which based on the popular constitutive models for the general caly soils. However, the buffer material which has swelling characteristics is considered not to be ordinary clay soils. So it is necessary to select the reliable constitutive models again. Therefor the proper models were selected again systematically in the several models which have been used for the assessment of the behavior of clay soils and the simulation analysis on the laboratory tests were carried out by using these models. From the result of the simulation analysis it appeared that the selected two models were alike to assess the behavior of the buffer material and the parameters which need to simulate the consolidation tests are different from those for the triaxial compression tests. Finally the analysis was conducted to evaluate the effect of the swelling of the overpack by the collosion and the self weight which causes the sedimentation of the overpack. From the analytical result, it was clarified that two kinds of parameter sets are necessary to evaluate the deformation and the stress of the buffer material in the engineered barrier system.

JAEA Reports

Assessment on Bearing Capacity of Buffer Material to Overpack

Hirai, Takashi; Tanai, Kenji; Kikuchi, Hirohito*; Takaji, Kazuhiko*; Onuma, Satoshi*

JNC TN8400 2003-031, 48 Pages, 2004/02

JNC-TN8400-2003-031.pdf:2.22MB

The objective of this report is to clarify the characteristics of the bearing capacity of the buffer material against the deformation of the overpack in the engineered barrier system. In the second progress report by JNC, it was reported that the well designed engineered barrier system is stable and safety on mechanical support of the overpack to ensure stability and stress which acts on the overpack by some analysis. However, the degree of the capacity to the ultimate state and the background datas of the design are not necessary clarified in the report. Therefore it is considered to be mportant to assess the ultimate state and make the relationship clear between deformation and bearing capacity of the overpack in the engineered barrier system. So the scale test and the simulation analysis were carried out for the longitudinal deformation of the overpack in the saturated buffer material constrained by the host rock. From the result of the scale test and the analysis it appears that the bearing capacity is increasing with the deformation of the overpack even if the bearing capacity is over the yielding force and the relationship between deformation and bearing capacity can be approximately expressed by the simple fanction.

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".

Oral presentation

Mechanical complex behavior analysis of buffer material and surrounding rock

Takaji, Kazuhiko*; Shigeno, Yoshimasa*; Tanai, Kenji; Nishimura, Mayuka

no journal, , 

no abstracts in English

Oral presentation

A Study on long term behavior of the near field in consideration of concrete support deterioration, 1; Constitutive model of concrete support deterioration

Shigeno, Yoshimasa*; Takaji, Kazuhiko*; Nishimura, Mayuka*; Tanai, Kenji

no journal, , 

no abstracts in English

Oral presentation

A Study on long term behavior of the near field in consideration of concrete support deterioration, 2; Analytical examination for pit disposal case

Nishimura, Mayuka*; Shigeno, Yoshimasa*; Takaji, Kazuhiko*; Tanai, Kenji

no journal, , 

no abstracts in English

Oral presentation

Extrusion behavior of bentonite buffer, 2; Analytical study on extrusion behavior

Takaji, Kazuhiko*; Inaba, Kaoru*; Matsumoto, Kazuhiro; Fujita, Tomo

no journal, , 

no abstracts in English

Oral presentation

Experimental examination about the heavy weight concrete strength, 1; Purpose and outline of experiment

Kojima, Kazuki; Kojima, Keidai; Fujita, Masateru; Hashimura, Hirohiko; Takaji, Kazuhiko*; Maenaka, Toshinobu*

no journal, , 

no abstracts in English

Oral presentation

Experimental examination about the heavy weight concrete strength, 2; Strength evaluation

Kojima, Kazuki; Fujita, Masateru; Nakanishi, Ryuji; Uryu, Mitsuru; Takaji, Kazuhiko*; Maenaka, Toshinobu*

no journal, , 

no abstracts in English

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