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Nakayama, Masashi
JAEA-Review 2023-032, 159 Pages, 2024/02
JAEA-Review-2023-032.pdf:19.37MB
The Horonobe Underground Research Laboratory (URL) Project is being pursued by the Japan Atomic Energy Agency (JAEA) to enhance the reliability of relevant technologies for geological disposal of high-level radioactive waste through investigating the deep geological environment within the host sedimentary rocks at Horonobe Town in Hokkaido, north Japan. In the fiscal year 2022, we continued R&D on "Study on near-field system performance in geological environment", "Demonstration of repository design options", and "Understanding of buffering behaviour of sedimentary rock to natural perturbations". These are identified as key R&D on challenges to be tackled in the Horonobe underground research plan for the fiscal year 2020 onwards. Specifically, "full-scale engineered barrier system (EBS) performance experiment" and "solute transport experiment with model testing" were carried out as part of "Study on near- field system performance in geological environment". "Demonstration of engineering feasibility of repository technology" and "evaluation of EBS behaviour over 100
C" were addressed for "Demonstration of repository design options". A study on "Understanding of buffering behaviour of sedimentary rock to natural perturbations" was also implemented in two areas, "evaluation of intrinsic buffering against endogenic and exogenic processes" and "development of techniques for evaluating excavation damaged zone (EDZ) self-sealing behaviour after backfilling". The Horonobe International Project (HIP) was initiated in February 2023 to promote research and development in collaboration with national and international organizations.
Nakayama, Masashi
JAEA-Review 2023-019, 70 Pages, 2023/11
JAEA-Review-2023-019.pdf:6.83MB
The Horonobe Underground Research Laboratory (URL) Project is being pursued by the Japan Atomic Energy Agency (JAEA) to enhance the reliability of relevant technologies for geological disposal of high-level radioactive waste through investigating the deep geological environment within the host sedimentary rocks at Horonobe Town in Hokkaido, north Japan. In the fiscal year 2023, we continue R&D on "Study on near-field system performance in geological environment", "Demonstration of repository design options", and "Understanding of buffering behaviour of sedimentary rocks to natural perturbations". These are identified as key R&D challenges to be tackled in the Horonobe underground research plan for the fiscal year 2020 onwards. In the "Study on near-field system performance in geological environment", we conduct the coupled analysis on the full-scale engineered barrier system performance experiment and test the coupled simulation code through comparison with different simulation codes in the international DECOVALEX-2023 collaboration project. Borehole investigations are also carried out for solute transport experiments in the Koetoi Formation. As for "Demonstration of repository design concept", we carry out in situ experiments and data analysis on concrete deterioration under the subsurface conditions. Geophysical surveys are also carried out around an experimental tunnel to be newly excavated at the 350m gallery and characterise the initial conditions of the excavation damaged zone. For the "Understanding of buffering behaviour of sedimentary rocks to natural perturbations", we analyse the results of the hydraulic disturbance tests conducted in previous years and understand the relationship between rock stress / stress state and fault / fracture hydraulic connectivity. Concerning the construction and maintenance of the subsurface facilities, the 350 m gallery is extended and shafts are sank to a depth of 500 m.
Nakayama, Masashi
JAEA-Review 2022-026, 66 Pages, 2022/11
JAEA-Review-2022-026.pdf:12.31MB
The Horonobe Underground Research Laboratory (URL) Project is being pursued by the Japan Atomic Energy Agency (JAEA) to enhance the reliability of relevant disposal technologies for geological disposal of High-level Radioactive Waste through investigations of the deep geological environment within the host sedimentary rock at Horonobe Town in Hokkaido, north Japan. In fiscal year 2022, we continue to conduct research on "Study on near-field system performance in geological environment", "Demonstration of repository design options", and "Understanding of buffering behaviour of sedimentary rocks to natural perturbations", which are the important issues shown in the Horonobe underground research plan from fiscal year 2020. The main studies to be conducted in fiscal year 2022 are as follows. As "Study on near-field system performance in geological environment", we will continue to the test under the simulated condition in which the heat generation by the high-level radioactive waste has subsides in the full-scale engineered barrier system (EBS) performance experiment. We will also conduct solute transport experiment with model testing that take into account the effects of organic matter, microbes, and colloids, and initiate borehole investigation to evaluate solute transport experiments on fractures distribute in Koetoi formation. As "Demonstration of repository design concept", we will continue experiment and analysis of concrete deterioration in the underground environment as a demonstration of remote technique for emplacement and retrievable. As a demonstration of the closure techniques, laboratory tests will be continued to investigate the mechanism of bentonite runoff behaviour, which could be a factor in changing the performance of backfill material, and to expand data on swelling and deformation behaviour. In addition, in-situ borehole closure tests will be conducted to evaluate the applicability of the closure method. As "Understanding of buffering behaviour of
Nakayama, Masashi
JAEA-Review 2022-025, 164 Pages, 2022/11
JAEA-Review-2022-025.pdf:12.25MB
The Horonobe Underground Research Laboratory (URL) Project is being pursued by the Japan Atomic Energy Agency (JAEA). The main aim of this project is to enhance the reliability of relevant disposal technologies for geological disposal of high-level radioactive waste through a comprehensive research and development (R&D) program in the deep geological environment within the host sedimentary rock at Horonobe in Hokkaido, north Japan. In fiscal year 2021, we continued R&D on three important issues specified in the "Horonobe Underground Research Plan from Fiscal Year 2020", which involve "Study on near-field system performance in geological environment", "Demonstration of repository design options", and "Understanding of buffering behaviour of sedimentary rock to natural perturbations". Specifically, "full-scale engineered barrier system (EBS) performance experiment" and "solute transport experiment with model testing" were carried out as part of "Study on near-field system performance in geological environment". "Demonstration of engineering feasibility of repository technology" and "evaluation of EBS behaviour over 100C' were addressed for "Demonstration of repository design options". A study on "Understanding of buffering behaviour of sedimentary rock to natural perturbations" was also implemented in two areas, "evaluation of intrinsic buffering against endogenic and exogenic processes" and "development of techniques for evaluating excavation damaged zone (EDZ) self-sealing behaviour after backfilling". The results of the R&D, along with those obtained in other departments of JAEA, will reinforce the technical basis for both repository implementation and safety regulation. For the sake of this, we will steadily proceed with this project in collaboration with relevant organizations and universities both domestically and internationally and also widely publish the plans and results of the R&D to ensure their transparency and technical reliability.
Nakayama, Masashi
JAEA-Review 2021-053, 133 Pages, 2022/02
JAEA-Review-2021-053.pdf:14.45MB
The Horonobe Underground Research Laboratory (URL) Project is being pursued by the Japan Atomic Energy Agency (JAEA). The main aim of this project is to enhance the reliability of relevant disposal technologies for geological disposal of high-level radioactive waste through a comprehensive research and development (R&D) program in the deep geological environment within the host sedimentary rock at Horonobe in Hokkaido, north Japan. In fiscal year 2020, JAEA continued R&D on three important issues specified in the "Horonobe Underground Research Plan from Fiscal Year 2020", which involve "Study on nearfield system performance in geological environment", "Demonstration of repository design options", and "Understanding of buffering behavior of sedimentary rock to natural perturbations". Specifically, 'full scale engineered barrier system (EBS) experiment' and 'solute transport experiment' were carried out as part of "Study on near-field system performance in geological environment". 'Development and testing of EBS emplacement / retrieval and tunnel closure technologies' and 'evaluation of EBS behavior over 100C' were addressed for "Demonstration of repository design options". A study on "Understanding of buffering behavior of sedimentary rock to natural perturbations" was also implemented in two areas, 'evaluation of hydromechanical responses of faults to water pressure changes' and 'development of techniques for evaluating self-sealing behavior of an excavation damaged zone after backfilling'. The results of the R&D, along with those obtained in other departments of JAEA, will reinforce the technical basis for both repository implementation and safety regulation. For the sake of this, JAEA will steadily proceed with this project in collaboration with relevant organizations and universities both domestically and internationally and also widely publish the plans and results of the R&D to ensure their transparency and technical reliability.
Nakayama, Masashi; Saiga, Atsushi
JAEA-Review 2020-042, 116 Pages, 2021/01
JAEA-Review-2020-042.pdf:10.33MB
The Horonobe Underground Research Laboratory Project will be conducted in three phases, namely "Phase 1: Surface-based investigations", "Phase 2: Construction Phase" (investigations during construction of the underground facilities) and "Phase 3: Operation phase" (research in the underground facilities). This report summarizes the results of the investigations for the 2019 fiscal year (2019/2020). The investigations, which are composed of "Geoscientific research" and "R and D on geological disposal technology", were carried out according to "Horonobe Underground Research Laboratory Project Investigation Program for the 2019 fiscal year". The results of these investigations, along with the results which were obtained in other departments of Japan Atomic Energy Agency (JAEA), are properly offered to the implementations and the safety regulations. For the sake of this, JAEA has proceeded with the project in collaboration with experts from domestic and overseas research organizations.
Hata, Koji*; Niunoya, Sumio*; Uyama, Masao*; Nakaoka, Kenichi*; Fukaya, Masaaki*; Aoyagi, Kazuhei; Sakurai, Akitaka; Tanai, Kenji
JAEA-Research 2020-010, 142 Pages, 2020/11
JAEA-Research-2020-010.pdf:13.74MB
JAEA-Research-2020-010-appendix(DVD-ROM).zip:149.9MB
In the geological disposal study of high-level radioactive waste, it is suggested that the excavation damaged zone (EDZ) which is created around a tunnel by the excavation will be possible to be one of the critical path of radionuclides. Especially, the progress of cracks in and around the EDZ with time affects the safety assessment of geological disposal and it is important to understand the hydraulic change due to the progress of cracks in and around EDZ. In this collaborative research, monitoring tools made by Obayashi Corporation were installed at a total of 9 locations in the three boreholes near the depth of 370 m of East Shaft at the Horonobe Underground Research Laboratory constructed in the Neogene sedimentary rock. The monitoring tool consists of one set of "optical AE sensor" for measuring of the mechanical rock mass behavior and "optical pore water pressure sensor and optical temperature sensor" for measuring of groundwater behavior. This tool was made for the purpose of selecting and analyzing of AE signal waveforms due to rock fracture during and after excavation of the target deep shaft. As a result of analyzing various measurement data including AE signal waveforms, it is able to understand the information on short-term or long-term progress of cracks in and around EDZ during and after excavation in the deep shaft. In the future, it will be possible to carry out a study that contributes to the long-term stability evaluation of EDZ in sedimentary rocks in the deep part of the Horonobe Underground Research Laboratory by evaluation based on these analytical data.
Sugiura, Yuki; Suyama, Tadahiro*; Tachi, Yukio
JAEA-Data/Code 2019-022, 40 Pages, 2020/03
JAEA-Data-Code-2019-022.pdf:2.22MB
Sorption behavior of radionuclides (RNs) in buffer materials, rocks and cementitious materials is one of the key processes in a safe geological disposal. This report focuses on updating of JAEA sorption database (JAEA-SDB) as a basis of integrated approach for the performance assessment (PA)-related distribution coefficient (K
) setting and development of mechanistic sorption models. K data and their quality assurance (QA) results were updated by focusing on the following systems as potential needs extracted from our recent activities on the K setting and development of mechanistic models, i.e., clay minerals, sedimentary rocks and cementitious materials. As a result, 6,702 K data from 60 references were added and the total number of K values in JAEA-SDB reached 69,679. The QA/classified K data reached about 72% for all K data in JAEA-SDB.
Miyara, Nobukatsu; Matsuoka, Toshiyuki
JAEA-Data/Code 2019-013, 8 Pages, 2020/01
JAEA-Data-Code-2019-013.pdf:1.45MBJAEA-Data-Code-2019-013-appendix(DVD-ROM)1.zip:239.91MBJAEA-Data-Code-2019-013-appendix(DVD-ROM)10.zip:346.69MBJAEA-Data-Code-2019-013-appendix(DVD-ROM)11.zip:237.95MBJAEA-Data-Code-2019-013-appendix(DVD-ROM)12.zip:335.05MBJAEA-Data-Code-2019-013-appendix(DVD-ROM)13.zip:335.0MBJAEA-Data-Code-2019-013-appendix(DVD-ROM)2.zip:433.26MBJAEA-Data-Code-2019-013-appendix(DVD-ROM)3.zip:360.88MBJAEA-Data-Code-2019-013-appendix(DVD-ROM)4.zip:292.24MBJAEA-Data-Code-2019-013-appendix(DVD-ROM)5.zip:315.31MBJAEA-Data-Code-2019-013-appendix(DVD-ROM)6.zip:426.42MBJAEA-Data-Code-2019-013-appendix(DVD-ROM)7.zip:286.49MBJAEA-Data-Code-2019-013-appendix(DVD-ROM)8.zip:187.61MBJAEA-Data-Code-2019-013-appendix(DVD-ROM)9.zip:826.1MB
As part of the research and development program on the geological disposal of high-level radioactive waste (HLW), the Horonobe Underground Research Center, a division of the Japan Atomic Energy Agency (JAEA), is implementing the Horonobe Underground Research Laboratory Project (Horonobe URL Project) with the aim at investigating sedimentary rock formations. This data collection is a compilation of Earthquake observation data acquired in the Horonobe Underground Research Project (Phase II).
Nakayama, Masashi; Ono, Hirokazu
JAEA-Research 2019-007, 132 Pages, 2019/12
JAEA-Research-2019-007.pdf:11.29MBJAEA-Research-2019-007-appendix(CD-ROM).zip:39.18MB
The Horonobe Underground Research Laboratory (URL) Project has being pursued by Japan Atomic Energy Agency (JAEA) to enhance the reliability of relevant disposal technologies through investigations of the deep geological environment within the host sedimentary formation at Horonobe, northern Hokkaido. The URL Project consists of two major research areas, "Geoscientific Research" and "Research and Development on Geological Disposal Technologies". The in-situ experiment for performance confirmation of engineered barrier system (EBS experiment) had been prepared from 2013 to 2014 fiscal year at GL-350m gallery, and heating by electric heater in simulated overpack had started in January, 2015. One of objectives of the EBS experiment is acquiring data concerned with Thermal-Hydrological-Mechanical-Chemical (THMC) coupled behavior. These data will be used in order to confirm the performance of engineered barrier system. This report shows following works had carried out at the GL-350 m gallery. Excavation of a test niche and a test pit, Setting buffer material blocks and a simulated overpack into the test pit, Backfilling the niche by compaction backfilling material and setting backfilling material blocks, Casting concrete type plug and contact grouting, Consolidate measurement system and start measuring.
Hanamuro, Takahiro; Saiga, Atsushi
JAEA-Review 2018-027, 125 Pages, 2019/02
JAEA-Review-2018-027.pdf:21.79MB
The Horonobe Underground Research Laboratory Project is planned to extend over a period 20 years. The investigations will be conducted in three phases, namely "Phase 1: Surface-based investigations", "Phase 2: Construction Phase" (investigations during construction of the underground facilities) and "Phase 3: Operation phase" (research in the underground facilities). This report summarizes the results of the investigations for the 2017 fiscal year (2017/2018). The investigations, which are composed of "Geoscientific research" and "R&D on geological disposal technology", were carried out according to "Horonobe Underground Research Laboratory Project Investigation Program for the 2017 fiscal year". The results of these investigations, along with the results which were obtained in other departments of Japan Atomic Energy Agency (JAEA), are properly offered to the implementations and the safety regulations. For the sake of this, JAEA has proceeded with the project in collaboration with experts from domestic and overseas research organizations.
Nakayama, Masashi
JAEA-Technology 2018-006, 43 Pages, 2018/08
JAEA-Technology-2018-006.pdf:5.32MBJAEA-Technology-2018-006-appendix(CD-ROM).zip:29.19MB
The Horonobe URL Project has being pursued by JAEA to enhance the reliability of relevant disposal technologies through investigations of the deep geological environment within the host sedimentary formation at Horonobe, Hokkaido. The URL Project proceeds in 3 overlapping phases, "Phase I: Surface-based investigations", "Phase II: Investigations during tunnel excavation" and "Phase III: Investigations in the underground facilities", over a period of around 20 years. The OP corrosion test was prepared from 2013 FY at Niche No.3, and heating by electric heater in simulated overpack started in November, 2014. The objective of the test is acquiring data concerned with corrosion of carbon steel OP. These data will be used in order to confirm the performance of engineered barrier system. In the OP corrosion test, the diameter of simulated OP and buffer material are 100 mm and 300 mm, respectively. Concrete support using low alkaline cement was used in order to investigate the effect of cementitious materials to OP corrosion behavior. We will measure corrosion potential of carbon steel, natural potential, pH in buffer material for several years. In this report, we describe how to make simulated OP and buffer material blocks, and set sensors, and so on.
Nakayama, Masashi; Niunoya, Sumio*; Miura, Norihiko*; Takeda, Nobufumi*
JAEA-Research 2017-016, 62 Pages, 2018/01
JAEA-Research-2017-016.pdf:19.99MB
The Horonobe URL Project has being pursued by JAEA to enhance the reliability of relevant disposal technologies through investigations of the deep geological environment within the host sedimentary formation at Horonobe, Hokkaido. The URL Project consists of 2 major research areas, "Geoscientific Research" and "Research and Development on Geological Disposal Technologies", and proceeds in 3 overlapping phases, over a period of around 20 years. Phase III (Investigations in the underground facilities) investigation was started in 2010 FY. The in-situ experiment for performance confirmation of engineered barrier system (EBS experiment) had started 2013 at GL-350 m gallery, and heating by electric heater in simulated overpack had started in January, 2015. One of objectives of the EBS experiment is acquiring data concerned with THMC coupled behavior. These data will be used in order to confirm the performance of engineered barrier system. This report shows consideration of concrete-type plug composition. The low alkaline cement developed by JAEA, called HFSC, was used for the plug. HFSC has used in construction test at the gallery as shotcrete in Horonobe URL.
Aoyagi, Kazuhei; Ishii, Eiichi; Ishida, Tsuyoshi*
Journal of MMIJ, 133(2), p.25 - 33, 2017/02
In the construction of a deep underground facility, the hydromechanical properties of the rock mass around an underground opening are changed significantly due to stress redistribution. This zone is called an excavation damaged zone (EDZ). In high-level radioactive waste disposal, EDZs can provide a shortcut for the escape of radionuclides to the surface environment. Therefore, it is important to develop a method for predicting the detailed characteristics of EDZs. For prediction of the EDZ in the Horonobe Underground Research Laboratory of Japan, we conducted borehole televiewer surveys, rock core analyses, and repeated hydraulic conductivity measurements. We observed that niche excavation resulted in the formation of extension fractures within 0.2 to 1.0 m into the niche wall, i.e., the extent of the EDZ is within 0.2 to 1.0 m into the niche wall. These results are largely consistent with the results of a finite element analysis implemented with the failure criteria considering failure mode. The hydraulic conductivity in the EDZ was increased by 3 to 5 orders of magnitude compared with the outer zone. The hydraulic conductivity in and around the EDZ has not changed significantly in the two years following excavation of the niche. These results show that short-term unloading due to excavation of the niche created a highly permeable EDZ.
Aoyagi, Kazuhei; Ishii, Eiichi
Dai-14-Kai Iwa No Rikigaku Kokunai Shimpojiumu Koen Rombunshu (Internet), 6 Pages, 2017/01
The objective of this research is to investigate the hydro-mechanical properties of excavation damaged zones (EDZs) along the galleries excavated in 250 m and 350 m depths. We conducted hydraulic tests, BTV observations and core analyses. As a result, in the 250 m gallery, the extent of the EDZ was 1.0 m into the gallery wall. The hydraulic conductivity was increased by 2 to 3 orders of magnitudes compared with that of intact rock. On the other hand, in the 350 m gallery, the extent of the EDZ was 0.4 m into the gallery wall; the hydraulic conductivity was increased by 5 orders of magnitudes compared with that of intact rock. We investaged the difference of the characteristics of the EDZs on the basis of competence factor and ductility index. As a result, it was estimated that an extent of an EDZ decreases with decrease of competence factor; a hydraulic conductivity in an EDZ increases with decrease of ductility index.
Nakashima, Hiroyoshi*; Koyama, Tomofumi*; Tatsuta, Keisuke*; Katayama, Tatsuo*; Aoyagi, Kazuhei
Dai-14-Kai Iwa No Rikigaku Kokunai Shimpojiumu Koen Rombunshu (Internet), 6 Pages, 2017/01
In this study, we created the three dimensional model based on equivalent continuum approach to study the penetration length and enhancement of the hydraulic conductivity of the rock mass. The developed numerical model was applied to the in situ grout injection conducted in the ventilation shaft of the Horonobe Underground Research Laboratory. We evaluated the hydraulic conductivity of the rock mass after the grout operation. As a result, hydraulic conductivity of the highly permeable fault was decreased in 4 orders of magnitude, which is almost consistent with the in situ hydraulic conductivity obtained from in situ Luegeon test after the grout injection. Thus the simulation method described in this paper can be applied to the evaluation of the efficiency of in situ grout injection.
Nakayama, Masashi; Matsuzaki, Tatsuji*; Niunoya, Sumio*
JAEA-Research 2016-010, 57 Pages, 2016/08
JAEA-Research-2016-010.pdf:10.81MBJAEA-Research-2016-010-appendix(CD-ROM).zip:31.42MB
The Horonobe URL Project has being pursued by JAEA to enhance the reliability of relevant disposal technologies through investigations of the deep geological environment within the host sedimentary formation at Horonobe, northern Hokkaido. The in-situ experiment for performance confirmation of engineered barrier system (EBS experiment) had been prepared from 2013 to 2014 fiscal year at G.L.-350m gallery, and heating by electric heater in simulated overpack had started in January, 2015. One of objectives of the experiment is acquiring data concerned with Thermal -Hydrological - Mechanical - Chemical coupled behavior. These data will be used in order to confirm the performance of engineered barrier system. In this report, It is summarized the production of casing drilling machine for large diameter, simulated overpack, buffer material blocks and backfilling material for EBS experiment.
Nakayama, Masashi; Ono, Hirokazu; Nakayama, Mariko*; Kobayashi, Masato*
JAEA-Data/Code 2016-005, 55 Pages, 2016/07
JAEA-Data-Code-2016-005.pdf:11.32MBJAEA-Data-Code-2016-005-appendix(CD-ROM).zip:32.68MB
The Horonobe URL Project has being pursued by JAEA to enhance the reliability of relevant disposal technologies through investigations of the deep geological environment within the host sedimentary formation at Horonobe, northern Hokkaido. The Project consists of two major research areas, "Geoscientific Research" and "Research and Development on Geological Disposal Technologies", and proceeds in three overlapping phases, "Phase I: Surface-based investigations", "Phase II: Investigations during tunnel excavation" and "Phase III: Investigations in the underground facilities". Phase III investigation was started in 2010 fiscal year. The in-situ experiment for performance confirmation of engineered barrier system (EBS experiment) had been prepared from 2013 to 2014 fiscal year at GL-350m gallery, and heating by electric heater in simulated overpack had started in January, 2015. One of objectives of the experiment is acquiring data concerned with Thermal-Hydrological-Mechanical-Chemical (THMC) coupled behavior. These data will be used in order to confirm the performance of engineered barrier system. This report summarizes the measurement data acquired from the EBS experiment from December, 2014 to March, 2016.
Nakayama, Masashi; Ono, Hirokazu; Tanai, Kenji; Sugita, Yutaka; Fujita, Tomoo
JAEA-Research 2016-002, 280 Pages, 2016/06
JAEA-Research-2016-002.pdf:16.21MB
The Horonobe Underground Research Laboratory (URL) Project has being pursued by Japan Atomic Energy Agency (JAEA) to enhance the reliability of relevant disposal technologies through investigations of the deep geological environment within the host sedimentary formation at Horonobe, northern Hokkaido. The URL Project consists of two major research areas, "Geoscientific Research" and "Research and Development on Geological Disposal Technologies", and proceeds in three overlapping phases, "Phase I: Surface-based investigations", "Phase II: Investigations during tunnel excavation" and "Phase III: Investigations in the underground facilities", over a period of around 20 years. Phase III investigation was started in 2010 fiscal year. The in-situ experiment for performance confirmation of engineered barrier system (EBS experiment) had been prepared from 2013 to 2014 fiscal year at G.L.-350m gallery (Niche No.4), and heating by electric heater in simulated overpack had started in January, 2015. One of objectives of the experiment is acquiring data concerned with Thermal-Hydrological-Mechanical-Chemical (THMC) coupled behavior. These data will be used in order to confirm the performance of engineered barrier system. In EBS experiment, the backfill material using mixture of bentonite and muck from Horonobe URL construction was used for backfilling a part of Niche No.4. This report shows the results of properties of the backfill material, confirmation test of compaction method and making backfill material block, and so on. From these results, it was confirmed that the backfill material would satisfy target value of the permeability and the swelling pressure.
Motoshima, Takayuki*; Fujita, Tomoo; Aoyagi, Kazuhei; Shirase, Mitsuyasu*; Nago, Makito*
Proceedings of 7th International Symposium on In-situ Rock Stress (RS 2016) (Internet), 9 Pages, 2016/05
