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Okihara, Mitsunobu*; Yahagi, Ryoji*; Iwatsuki, Teruki; Takeuchi, Ryuji; Murakami, Hiroaki
JAEA-Technology 2019-021, 77 Pages, 2020/03
JAEA-Technology-2019-021.pdf:5.33MB
One of the major subjects of the ongoing geoscientific research program, the Mizunami Underground Research Laboratory (MIU) Project in the Tono area, central Japan, is accumulation of knowledge on monitoring techniques of the geological environment. In this report, the conceptual design of the monitoring system for groundwater pressure and water chemistry was carried out. The currently installed and used system in research galleries at various depths was re-designed to make it possible to collect groundwater and observe the water pressure on the ground.
Tsuji, Masakuni*; Nakashima, Hitoshi*; Saito, Akira*; Okihara, Mitsunobu*; Sato, Toshinori
45th Annual Waste Management Conference (WM 2019); Encouraging Young Men & Women to Achieve Their Goals in Radwaste Management, Vol.7, p.4749 - 4763, 2020/01
A rock excavation grouting technology has been recently studied as significant technology for reducing the ingress of water into the deep repository. However, it has not been studied for applying to the coastal region, where it is discussed to be a more suitable region for the geological disposal in Japan. The latest material called colloidal silica grout (CSG) is good for sealing narrow fractures but is known to be sensitive to the salinity of groundwater because of its gelling property with salt accelerator. Although the gelling of CSG can be controlled by adding an acidic pH adjuster, the methodology for delivering the appropriate grout is not well established for such conditions of saline groundwater. Therefore, this research project was established to enhance the existing rock grouting technology for deep repositories.
Tsuji, Masakuni*; Okihara, Mitsunobu*; Nakashima, Hitoshi*; Saito, Akira*; Aoyagi, Kazuhei; Sato, Toshinori
Dai-47-Kai Gamban Rikigaku Ni Kansuru Shimpojiumu Koenshu (Internet), p.266 - 271, 2020/01
As engineering technique for geological disposal, a lot of advancement development of the grout technology has been performed. But the design, construction method in consideration of the properties of matter acquisition and mechanism of the hardening that assumed a seawater condition bottom is non-establishment. As we carried out the knowledge under saline water, the basic properties acquisition, the penetration properties acquisition, a study revue based on such situation.
Tsuji, Masakuni*; Aoyagi, Kazuhei; Nakashima, Hitoshi*; Okihara, Mitsunobu*; Sato, Toshinori
Proceedings of the Nordic Grouting Symposium 2019 (Internet), 15 Pages, 2019/09
This paper shows an overall result of the 3-year study on the characterisation of the colloidal silica grout (CSG) under saline groundwater, aiming to enhance the existing rock grouting technology, especially for the CSG under the saline groundwater. As a first step, we performed the survey of the latest grouting technology of CSG. We developed a feasible mixing methodology and have obtained the various CSG's properties impacted by the salty mixing water or submerged by saline water. Moreover, we proposed a theory for the grout penetration under saline water and performed the injection tests. In the second workshop in the final year, our overall findings in this study were recognised to attain some progress in the development of the grouting technology.
Martikainen, J.*; Tsuji, Masakuni*; Schatz, T.*; Nakashima, Hitoshi*; Okihara, Mitsunobu*; Aoyagi, Kazuhei; Sato, Toshinori
Proceedings of the Nordic Grouting Symposium 2019 (Internet), 13 Pages, 2019/09
This paper shows a result of the part of the study on characterisation of penetration of the colloidal silica grout (CSG) under saline groundwater, aiming to understand the impact of salinity on grout penetration by verifying the improved penetration theory with laboratory tests. This theory was proposed to add a time factor 
to the existing penetration theory of Funehag, especially under the saline groundwater conditions. A series of grout injection tests by the fracture test system were performed. The CSG of one European and Japanese were injected in the system, filled with the five different groundwater simulants. All no-flow tests were successful, resulting in the formation of relatively homogeneous gelled zones. Based on the analysis of acquired , it was found that as an alternative method, designing a longer gel time by multiplying the inverse value of can be proposed to attain the required penetration. Although the results were fruitful, further investigation is necessary to develop this penetration theory.
Toguri, Satohito*; Yahagi, Ryoji*; Okihara, Mitsunobu*; Takeuchi, Nobumitsu*; Kurosaki, Hiromi*; Matsui, Hiroya
JAEA-Technology 2018-017, 161 Pages, 2019/03
JAEA-Technology-2018-017.pdf:28.26MB
The Japan Atomic Energy Agency has been conducting research on three critical issues for development of: engineering techniques for underground construction, modelling techniques of mass transfer and tunnel backfilling methods at the Mizunami Underground Research Laboratory on the basis of Medium to Long-Term Plan of Japan Atomic Energy Agency. This report describes the overall plan of in-situ test to backfill a part of Mizunami Underground Research Laboratory, which is planned for "development of tunnel backfilling method".
Toguri, Satohito*; Okihara, Mitsunobu*; Tsuji, Masakuni*; Nakashima, Hitoshi*; Sugiyama, Hirokazu*; Saito, Akira*; Sato, Toshinori; Aoyagi, Kazuhei; Masunaga, Kosuke
JAEA-Research 2017-013, 131 Pages, 2018/02
JAEA-Research-2017-013.pdf:8.49MB
The discussions on scientifically promising site for the geological disposal has been made at the council of studying group on techniques for geological disposal of radioactive wastes, which is held by Resources and Energy Agency. From the aspect of ensuring safety during the transportation of disposal waste, the coastal area is discussed to be a more suitable area. This report shows the result of the first year of this project as following items; Study on the state-of-art technology and remain tasks; laboratory tests on characterization of colloidal silica grout under sea water; Study on the development of grouting technology (design and the evaluation method of influence on the rock mass).
Tsuji, Masakuni*; Okihara, Mitsunobu*; Nakashima, Hitoshi*; Sato, Toshinori; Aoyagi, Kazuhei
Proceedings of 6th East Asia Forum on Radwaste Management Conference (EAFORM 2017) (Internet), 6 Pages, 2017/12
Regarding the engineering technology, the rock grouting has been recently studied as one of the most important technologies. Although the cement grout has not been reported to be affected by the sea water, the latest grouting material called colloidal silica grout is known to be sensitive to the saline water. The mechanism of its affection by sea water is not clear and its grouting methodology in such condition is not yet established either. Therefore, we studied on the latest grouting technologies for geological disposal in Nordic countries and Japan by article survey and a grouting workshop. As a result, it was found that the approach for countermeasures in grouting under sea water is different between Japan, Sweden, and Finland, which are based respectively on the mixture, on the design method, and on the controlling method. It seems that the best solution against this problem is to establish a hybrid and optimal grouting methodology under sea water by combining each country's developed grouting technology in the near future for saline condition, which is respectively based on mixing, design, and controlling method.
Sanada, Hiroyuki; Sato, Toshinori; Horiuchi, Yasuharu*; Mikake, Shinichiro; Okihara, Mitsunobu*; Yahagi, Ryoji*; Kobayashi, Shinji*
Tunnelling and Underground Space Technology, 50, p.68 - 78, 2015/08
Times Cited Count：5 Percentile：19.84(Construction & Building Technology)The Japan Atomic Energy Agency (JAEA) is implementing the Mizunami Underground Research Laboratory (MIU) Project to establish the scientific and technological basis for the geological disposal of High-level Radioactive Waste (HLW) in crystalline rocks. Excavation cycle times were recorded during the Ventilation Shaft sinking and compared with the planned excavation cycle times for evaluation of the baseline design plan. This included review of the cycle times in the design process and comparison with the actual construction results. The recorded results indicate that actual cycle times were twice as long as the design plan. This paper describes discussions on differences in cycle times between the design and actual times.
Kobayashi, Shinji*; Niimi, Katsuyuki*; Okihara, Mitsunobu*; Tsuji, Masakuni*; Yamada, Toshiko*; Sato, Toshinori; Mikake, Shinichiro; Horiuchi, Yasuharu*; Aoyagi, Yoshiaki
JAEA-Technology 2014-035, 172 Pages, 2015/01
JAEA-Technology-2014-035.pdf:91.27MB
The researches on engineering technology in the Mizunami Underground Research Laboratory (MIU) plan consists of (1) development of design and construction planning technologies, (2) development of construction technology, (3) development of countermeasure technology, (4) development of technology for security, and (5) development of technologies regarding restoration or reversal and mitigating of the excavation effect. To develop design and construction planning technologies, and countermeasure technology, the analysis of measured data during earthquake and seismic movement characteristics at deep underground, and the examination of grouting method were carried out. The knowledge of the seismic movements at deep underground was obtained by which observation records of seismometers at Mizunami underground research laboratory were analyzed to verify the earthquake-resistant design of the shafts and tunnels. As for" Study on grouting method at deep underground", Existing post-grouting methods for crystalline rock were reviewed, the applicability of pre-grouting technology was evaluated and study on experiment plan in MIU was carried out following the previous year.
Sanada, Hiroyuki; Sato, Toshinori; Horiuchi, Yasuharu*; Mikake, Shinichiro; Okihara, Mitsunobu*; Yahagi, Ryoji*; Kobayashi, Shinji*
Proceedings of 8th Asian Rock Mechanics Symposium (ARMS-8) (USB Flash Drive), 7 Pages, 2014/10
The Japan Atomic Energy Agency (JAEA) is implementing the Mizunami Underground Research Laboratory (MIU) Project to establish the scientific and technological basis for the geological disposal of High-level Radioactive Waste (HLW) in crystalline rocks. Excavation cycle times were recorded during the Ventilation Shaft sinking and compared with the planned excavation cycle times for evaluation of the baseline design plan. This included review of the cycle times in the design process and comparison with the actual construction results. The recorded results indicate that actual cycle times were twice as long as the design plan. This paper describes discussions on differences in cycle times between the design and result.
Fukaya, Masaaki*; Noda, Masaru*; Hata, Koji*; Takeda, Yoshinori*; Akiyoshi, Kenji*; Ishizeki, Yoshikazu*; Kaneda, Tsutomu*; Sato, Shin*; Shibata, Chihoko*; Ueda, Tadashi*; et al.
JAEA-Technology 2014-019, 495 Pages, 2014/08
JAEA-Technology-2014-019.pdf:82.23MB
The researches on engineering technology in the Mizunami Underground Research Laboratory (MIU) plan consists of (1) research on engineering technology deep underground, and (2) research on engineering technology as a basis of geological disposal. The former research is mainly aimed in this study, which is categorized in (a) development of design and construction planning technologies, (b) development of construction technologies, (c) development of countermeasure technologies, and (d) development of technologies for security. In this study, the researches on engineering technology are being conducted in these four categories by using data measured during construction as a part of the second phase of the MIU plan.
Tsuji, Masakuni*; Nobuto, Jun*; Okihara, Mitsunobu*; Sugita, Yutaka; Fujita, Tomoo; Shinkai, Fumiaki
Doboku Gakkai Heisei-22-Nendo Zenkoku Taikai Dai-65-Kai Nenji Gakujutsu Koenkai Koen Gaiyoshu (DVD-ROM), p.93 - 94, 2010/09
no abstracts in English
Nobuto, Jun*; Okihara, Mitsunobu*; Kobayashi, Shinji*; Shinkai, Fumiaki
no journal, ,
no abstracts in English
Hokari, Toshiyuki*; Okihara, Mitsunobu*; Kishi, Atsuyasu; Mizuno, Takashi; Miyakawa, Kazuya
no journal, ,
Safety assessment for radioactive waste disposal or CO
sequestration requires in-situ groundwater conditions, which have been investigated in use of boreholes. Since those disposal facilities are to be set deep under the ground, boreholes would be completed with steel casings and cementing for wall protection. It is known that the well completion affects the groundwater conditions. This report conducted a new investigation on the groundwater conditions in JAEA Horonobe, and discusses transition of the water conditions, which would be induced by the well completion, in addition to existing water condition data.
Hokari, Toshiyuki*; Okihara, Mitsunobu*; Kishi, Atsuyasu*; Mizuno, Takashi; Miyakawa, Kazuya
no journal, ,
no abstracts in English
Masunaga, Kosuke; Sato, Toshinori; Okihara, Mitsunobu*; Tsuji, Masakuni*; Nakashima, Hitoshi*; Saito, Akira*
no journal, ,
Study on characterization of liquid-type colloidal silica grout under sea water has been performed for the countermeasures against water inflow in the underground construction. This report shows the outline of this study.
Tsuji, Masakuni*; Okihara, Mitsunobu*; Nakashima, Hitoshi*; Saito, Akira*; Sato, Toshinori; Aoyagi, Kazuhei
no journal, ,
Study on characterization of liquid-type colloidal silica grout under sea water has been performed. Status of technology for grouting in the field of geological disposal in foreign countries has been understood by literature survey and site inspection.
Nakashima, Hitoshi*; Okihara, Mitsunobu*; Tsuji, Masakuni*; Saito, Akira*; Sato, Toshinori; Masunaga, Kosuke
no journal, ,
Study on characterization of liquid-type colloidal silica grout under sea water has been performed. This report shows the results of laboratory tests.
Tsuji, Masakuni*; Okihara, Mitsunobu*; Nakashima, Hitoshi*; Sato, Toshinori; Masunaga, Kosuke*
no journal, ,
Study on characterisation of colloidal silica grout under sea water including developing theoretical model and numerical simulation applicable to sea water has been performed.
