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Nomoto, Kosuke*; Matsui, Mikio*; Inoue, Hiroyuki*; Yoshino, Naoto; Karasaki, Kenji*; Ito, Kazumasa*
JNC TJ8400 2005-005, 94 Pages, 2005/02
JNC-TJ8400-2005-005.pdf:7.92MB
In the safety assessment at geological disposal of High Level Nuclear Waste, it is necessary to understand several properties like hydrological, geological and chemical properties of the disposal site by site investigations. The investigation results should project to the ground water flow modeling, migration modeling and the parameter assignment of these models. Japan Nuclear cycle Development Institute is going to carry out two Underground Research Laboratory plans in order to push on with the project and help to make up the safety criteria of the geological disposal. Horonobe is one area of these plans. In Horonobe, following properties were identified./-There are saline and fresh water./-There is dissolved gas in the underground water./-The underground of some area has high water pressure./In this study, the analysis considering above properties were carried out for understanding of hydrological properties in sedimentary rock. In addition, the affection to the water flow and migration influenced by the results were examined.
Yoshino, Naoto; Miyanomae, Shunichi*; Inoue, Hiroyuki*; Nashimoto, Yutaka*
JNC TJ8400 2005-004, 166 Pages, 2005/02
JNC-TJ8400-2005-004.pdf:4.59MB
In this paper, following two issues were examined and estimated, (1) The influence of near field condition factor to the dynamical behavior of sedimentary soft rock (2) The long term estimation of the dynamical behavior considering the condition of Horonobe area As the study about the influence of near field condition factor to the dynamical behavior of sedimentary soft rock, the thermal factor was focused on and the laboratory tests using test pieces which were sampled in Horonobe area were carried out under the water temperature were 20 degrees and 80 degrees. As a result, the time dependence parameter in variable-compliance-type constitutive-equation could be obtained. And comparison between creep property under 20 degrees and 80 degrees was conducted. In addition, the general properties of sedimentary soft rock under several conditions were identified by the survey of the literature. And the way how to confirm the dynamical properties of sedimentary soft rock with in-situ test were presented. For the study on the short-term and long-term stability of rock surroundig buffer materials, numerical simulations were carried out assuming several conditions. The direction of disposal tunnels and the ratio of rock strength by initial stress were estimated to be the main factor affecting the short-term stability of rock. Time dependency of rock and the stiffness of buffer material were estimated to be the main factor affecting the long-term stability of rock.
Yoshino, Naoto; Nomoto, Kosuke*; Matsui, Mikio*; Nashimoto, Yutaka*
JNC TJ8400 2004-035, 227 Pages, 2005/01
JNC-TJ8400-2004-035.pdf:23.11MB
There are various uncertainty factors in the safety assessment for the geological disposal of High Level Nuclear Waste. And it is difficult to eliminate these uncertainty factors completely. Then it is important to evaluate the various uncertainty factors quantitatively for the safety assessment of the geological disposal. Japan Nuclear Cycle Development Institute focused on the groundwater flow analysis and studied about following issues in 2003 in order to quantify the variance of values which obtained by field investigation or numerical analysis. (1)The method to estimate the hydraulic conductivity and quantify the variability of estimated hydraulic conductivity. (2)The quantification of the key parameter's variability based on probability flow rate analysis. (3)Case study by the vertical two dimensional field. Two-dimensional numerical simulation program in which the uncertainty of the reach point in the ground water flow can be estimated was developed in above subjects. In this study, following three issues are studied (1)verification about the variance of the reach point estimated by 2-dimensional simulation program (2)development of 3-dimensional simulation program (3)Case study by 3-dimensional simulation program
Inoue, Hiroyuki*; Ishiguro, Takeshi*; Kuji, Masayoshi*; Yoshino, Naoto
JNC TJ8400 2004-014, 59 Pages, 2004/02
JNC-TJ8400-2004-014.pdf:5.57MB
In this paper, authors examined the properties of sedimentary soft rock which might affect the groundwater flow rate and flow path in the sedimentary soft rock. As a general sample of sedimentary soft rock, we focused on the rock of HORONOBE area in HOKKAIDO prefecture. Then, following four issues were examined.1) a study of numerical flow rate analysis considering the difference of water density in the sedimentary soft rock.2) the hydro-geological modeling of HORONOBE area and a fundamental study of water pressure and saline density in HORONOBE area.3) a fundamental study of numerical coupling analysis about groundwater flow rate ,the difference of underground temperature, rock pressure and deformation. 4) a study about best performance of numerical flow rate analysis program.As a result, hydro-geological modeling of HORONOBE area using the information before 2002 as input data was succeeded by using the basic geological model which was made by IMAI et al,. And the applicability of TOUGH2 program as analysis method considering the density difference of underground water in sedimentary soft rock was verified. Then, we will be able to simulate underground flow considering the difference of saline density and specific water pressure in HORONOBE area. In addition, the applicability of TOUGH-FLAC program in which TOUGH2 was coupled with FLAC3D and consider rock pressure and deformation was verified. The best numerical performance of TOUGH2 program was studied in order to deal with large scale simulations. Then, it was shown that efficient method of the best numerical performance about TOUGH2 was possible.
Inoue, Hiroyuki*; Ishiguro, Takeshi*; Kuji, Masayoshi*; Yoshino, Naoto
JNC TJ8400 2004-013, 137 Pages, 2004/02
JNC-TJ8400-2004-013.pdf:22.48MB
In this paper, authors examined the properties of sedimentary soft rock which might affect the groundwater flow rate and flow path in the sedimentary soft rock. As a general sample of sedimentary soft rock, we focused on the rock of HORONOBE area in HOKKAIDO prefecture. Then, following four issues were examined. 1) a study of numerical flow rate analysis considering the difference of water density in the sedimentary soft rock. 2) the hydro-geological modeling of HORONOBE area and a fundamental study of water pressure and saline density in HORONOBE area. 3) a fundamental study of numerical coupling analysis about groundwater flow rate ,the difference of underground temperature, rock pressure and deformation. 4) a study about best performance of numerical flow rate analysis program. As a result, hydro-geological modeling of HORONOBE area using the information before 2002 as input data was succeeded by using the basic geological model which was made by IMAI et al,. And the applicability of TOUGH2 program as analysis method considering the density difference of underground water in sedimentary soft rock was verified. Then, we will be able to simulate underground flow considering the difference of saline density and specific water pressure in HORONOBE area. In addition, the applicability of TOUGH-FLAC program in which TOUGH2 was coupled with FLAC3D and consider rock pressure and deformation was verified. The best numerical performance of TOUGH2 program was studied in order to deal with large scale simulations. Then, it was shown that efficient method of the best numerical performance about TOUGH2 was possible.
Inoue, Hiroyuki*; Yoshino, Naoto; Miyanomae, Shunichi*; Mizutani, Kazuhiko*; Noda, Kenji*
JNC TJ8400 2004-005, 161 Pages, 2004/02
JNC-TJ8400-2004-005.pdf:18.59MB
In this study, the laboratory mechanical tests of sedimentary soft rock sampled at HORONOBE area in HOKKAIDO prefecture were conducted in order to build the confidence of OKUBO model for long term deformation of sedimentary rock. And the stability of rock around tunnel in building under the condition assumed the underground of HORONOBE area was examined by numerical simulation using information of boring data obtained before 2002 year. As a result, authors could obtain many values of parameter in OKUBO model under various conditions. These conditions have the difference of temperature and water saturation. In addition, the life time in creep predicted by OKUBO model could be compared with the real one. And numerical simulations, assuming various conditions such as stiffness of buffer material and yielding of support, had been carried out to evaluate the long-term stability of rock surrounding buffer material. Results show the decreasing tendency of time dependency of rock.
Yoshino, Naoto; Nashimoto, Yutaka*; Matsui, Mikio*; Ito, Setsuo*; Nomoto, Kosuke*
JNC TJ8400 2003-071, 63 Pages, 2004/01
JNC-TJ8400-2003-071.pdf:43.22MB
In this paper authors focused on the uncertainty of the groundwater modeling, and following three issues are examined in order to estimate the spatial variance in the modeling field quantitatively; 1.The method to estimate the hydraulic conductivity and quantify the variability of estimated hydraulic conductivity. 2.The quantification of the key parameter's variability based on probability flow rate analysis. 3.Case study by the vertical two dimensional field.
Inoue, Hiroyuki*; Minami, Kosuke*
JNC TJ8400 2002-061, 126 Pages, 2003/01
JNC-TJ8400-2002-061.pdf:3.79MB
When it thinks about a stratum disposition system of high-level radioactive waste, it is important to evaluate the long-term mechanical displaced behavior of the near field bedrock which is boundary condition of the engineered barrier that should be evaluated based on the reality. In this research, three following examination was carried out for reliability improvement of long-term dynamic deformation behavior estimate. (1)We evaluated the sedimentary rock of Horonobe where we used Okubo model as while changing hydraulic condition and temperature condition. (2)We carried out the model experiment that inner pressure acted on in order to grasp a movement of near field bedrock. (3)We examined model to evaluate that. As a result, the following things were provided. (1)Sedimentary rock of Horonobe is easy to cause strength degradation for being wet and dry cycles. When the rock is saturated after drying, it is broken along potential cracking. The rock reacts for a change of moisture content sensitively. In addition, a variation of the strength occurs in a little depth remainder. This diffuseness gave the strong influence on failure time. (2)Big plastic deformation may not do elasto-plasticity behavior according to theory for stress modification of rock mass. (3)We think with one of the factor that it produces remainder in prediction and real creep hour that there is as "m = n (conatnt of Okubo model)" simply. Therefore we collect data after peak, and it is necessary to grasp "m /n ". In addition, it is necessary to improve "n" in the model which we can change by environment and stress state on the way.
Inoue, Hiroyuki*; Noda, Kenji*
JNC TJ8400 2002-011, 95 Pages, 2002/02
JNC-TJ8400-2002-011.pdf:9.14MB
When a formation disposal system is thought about, it is important to evaluate long-term dynamics behavior of boundary condition and near field bedrock of an artificial barrier adequately. In this study, three matters were executed for improvement of a dependability of the evaluation as follows. (1)Creep test was executed as purpose by dependability improvement of evaluation technique of creep problem by Okubo model. Okubo model constant was calculated than the unconfined compression test which let strain rate change with true rock, and the creep test which the constant was used, and estimated breaking time was done. As a result, the estimation of breaking time by Okubo model almost suffered according to the estimation although a variation of test-piece influenced it. (2)A tunnel model apparatus was produced in the purpose which grasped near field bedrock behavior, and it was tested. Simulation rock test body of 1m 
1m 0.5m was used for a test, and 15cm tunnel excavation was carried out in an initial stress bottom. Quantities of inner space displacement were measured in a test, and a hardness-test was done after dismantlement, and looseness area was grasped quantitatively. As a result, the looseness area was able to be estimated with about 17.5cm than tunnel center position. (3)A test approach in deep underground laboratory was examined, and examination / the in situ test which took advantage of rock core analysis / borehole as purpose and done examination item by grip of long-term bedrock behavior (a bord is taken advantage of, and bord itself is used) was shown. In addition, layout of the deep underground laboratory which carried out various tests about long-term behavior in 3 depth was shown.