Refine your search:     
Report No.
 - 
Search Results: Records 1-20 displayed on this page of 294

Presentation/Publication Type

Initialising ...

Refine

Journal/Book Title

Initialising ...

Meeting title

Initialising ...

First Author

Initialising ...

Keyword

Initialising ...

Language

Initialising ...

Publication Year

Initialising ...

Held year of conference

Initialising ...

Save select records

Journal Articles

Current status of geological disposal by "all-Japan" activities, 4; Repository design and engineering technology (2)

Motoshima, Takayuki*; Matsui, Hiroya; Kawakubo, Masahiro*; Kobayashi, Masato*; Ichimura, Tetsuhiro*; Sugita, Yutaka

Nihon Genshiryoku Gakkai-Shi ATOMO$$Sigma$$, 64(3), p.163 - 167, 2022/03

no abstracts in English

Journal Articles

Evaluation of acoustic anisotropy of granite by surface wave measurements

Okano, Aoi*; Kimoto, Kazushi*; Matsui, Hiroya

Dai-15-Kai Iwa No Rikigaku Kokunai Shimpojiumu Koen Rombunshu (Internet), p.633 - 636, 2021/01

This study evaluates the acoustic anisotropy of granite using surface waves. It is well-known that granite shows acoustic anisotropy due to preferentially oriented microcracks. Therefore it may be possible to gain information on the microcracks from the measurement of the acoustic anisotropy. In the conventional rock core elastic wave test, acoustic anisotropy has been evaluated by the ultrasonic transmission test. However, it is difficult to apply this method to field measurement and irregularly-shaped specimens. Therefore, in this study, we attempted to evaluate the acoustic anisotropy of granite using surface waves. By this method, the acoustic anisotropy was evaluated based on the changes in the surface wave amplitude, velocity, and frequency when the transmission direction was varied stepwise at a constant angle. As a result, the proposed surface wave technique evaluated acoustic anisotropy successfully. Furthermore, it was found that the acoustic anisotropy emerges because the microcracks change the apparent rigidity of the granite specimen.

Journal Articles

Permeability measurement for macro-fractured Horonobe mudstone

Kamata, Kento*; Nara, Yoshitaka*; Matsui, Hiroya; Ozaki, Yusuke

Dai-15-Kai Iwa No Rikigaku Kokunai Shimpojiumu Koen Rombunshu (Internet), p.205 - 209, 2021/01

When considering the projects such as radioactive waste disposal, it is important to evaluate the confinement performance of underground substances in rock mass. However, the change in permeability of macro-fractured mudstone has not been sufficiently studied. Therefore, in this study, we investigated its effect on permeability by introducing a macro-fracture into a cylindrical specimen of mudstone distributed in the Horonobe area, Hokkaido. First, the hydraulic conductivity was measured by subjecting a specimen with a macro-fracture introduced by a brazilian test to a falling head permeability test. After that, it was compared with the hydraulic conductivity of the intact specimen measured by the transient pulse method. As a result, it was confirmed that the hydraulic conductivity was increased by about one order due to the introduction of macro-fracture. The increase rate of hydraulic conductivity obtained from the results of this research was smaller than that of previous researches using granite and basalt.

JAEA Reports

Mizunami Underground Research Laboratory Project, Annual report for fiscal year 2018

Takeuchi, Ryuji; Iwatsuki, Teruki; Matsui, Hiroya; Nohara, Tsuyoshi; Onoe, Hironori; Ikeda, Koki; Mikake, Shinichiro; Hama, Katsuhiro; Iyatomi, Yosuke; Sasao, Eiji

JAEA-Review 2020-001, 66 Pages, 2020/03

JAEA-Review-2020-001.pdf:7.6MB

The Mizunami Underground Research Laboratory (MIU) Project is being pursued by the Japan Atomic Energy Agency (JAEA) to enhance the reliability of geological disposal technologies through investigations of the deep geological environment in the crystalline rock (granite) at Mizunami City, Gifu Prefecture, central Japan. On the occasion of JAEA reformation in 2014, JAEA identified three remaining important issues on the geoscientific research program based on the synthesized latest results of research and development (R&D): "Development of countermeasure technologies for reducing groundwater inflow", "Development of modeling technologies for mass transport" and "Development of drift backfilling technologies". The R&D on three remaining important issues have been carrying out in the MIU Project. In this report, the current status of R&D and construction activities of the MIU Project in fiscal year 2018 is summarized.

Journal Articles

Result of seismic motion observation from ground surface to 500m depth at Mizunami Underground Research Laboratory and its detailed analysis

Matsui, Hiroya; Watanabe, Kazuhiko*; Mikake, Shinichiro; Niimi, Katsuyuki*; Kobayashi, Shinji*; Toguri, Satohito*

Dai-47-Kai Gamban Rikigaku Ni Kansuru Shimpojiumu Koenshu (Internet), p.293 - 298, 2020/01

Japan Atomic Energy Agency has been observed seismic motions induced by earthquakes, at ground surface, galleries at 100m, 300m and 500m depth of Mizunami underground research laboratory for over 10 years. The results suggested that the amplitude of the seismic motion decreases with depth as the previous study on crystalline rock at Kamaishi mine indicated. Detailed analysis on the observed seismic motions shows that the Fourier amplitude and the phase difference of the earthquake occurred near epicenter correspond with the one calculated by one-dimensional multiple reflection theory.

Journal Articles

A Study on the propagation characteristics of surface waves in granite based on ultrasonic measurements

Kimoto, Kazushi*; Okano, Aoi*; Saito, Takayasu*; Sato, Tadanobu*; Matsui, Hiroya

Doboku Gakkai Rombunshu, A2 (Oyo Rikigaku) (Internet), 76(2), p.I_97 - I_108, 2020/00

AA2020-0209.pdf:2.72MB

This study investigates the propagation characteristics of surface wave traveling in a random heterogeneous medium. For this purpose, ultrasonic measurements are performed on a granite block as a typical randomly heterogeneous medium. In this measurement, a line-focus transducer is used to excite ultrasonic waves, whereas a laser Doppler vibrometer is used to pickup the ultrasonic motion on the surface of the granite block. The measured waveforms are analysed in the frequency domain to evaluate the travel-time for each measurement point based on the Fermat's principle. From the ensemble of travel-times, the probability distribution is established as a function of travel-distance. The uncertainty of the travel-time and its spatial evolution are then investigated using the standard deviation of the travel-time as a measure of the uncertainty. As a result, it was found that the uncertainty is approximately proportional to the mean travel-time divided by the square root travel-distance.

Journal Articles

In-situ backfilling experiment of the small scall drift by spray method in Mizunami Underground Research Laboratory, Japan

Matsui, Hiroya; Yahagi, Ryoji*; Ishizuka, Hikaru*; Toguri, Satohito*

WIT Transactions on Ecology and the Environment, Vol.247, p.145 - 159, 2020/00

In situ backfilling experiment using spray method in the small scale drift (approximately 4 by 3 m scale) was conducted at 500 m depth in Mizunami Underground Research Laboratory (MIU) established by JAEA (Japan Atomic Energy Agency). The backfill material consists of sand and bentonite. Specification for the backfill material was designed to satisfy the target permeability of generic host rock (10$$^{-8}$$ m/sec) assumed by NUMO. In this case, effective clay density should be 0.4 Mg/m$$^{3}$$ or more. Quality control of the material before backfilling was performed by setting the initial water contents (average 14%) based on the results of the laboratory testing and preliminary spray testing on ground surface. Densities of the backfilled material measured at any points satisfied the specification and the results suggested the establishment of the practical quality control methodology of the backfilling by spray method under actual deep geological environment. The in situ experiment was sponsored by METI (Ministry of Environment, Trade and Industry).

JAEA Reports

Mizunami Underground Research Laboratory Project, Plan for fiscal year 2019

Takeuchi, Ryuji; Iwatsuki, Teruki; Matsui, Hiroya; Ikeda, Koki; Mikake, Shinichiro; Hama, Katsuhiro; Iyatomi, Yosuke; Matsuoka, Toshiyuki; Sasao, Eiji

JAEA-Review 2019-014, 30 Pages, 2019/10

JAEA-Review-2019-014.pdf:4.72MB

The Mizunami Underground Research Laboratory (MIU) Project is being pursued by the Japan Atomic Energy Agency(JAEA) to enhance the reliability of geological disposal technologies through investigations of the deep geological environment in the crystalline host rock(granite) at Mizunami City, Gifu Prefecture, central Japan. On the occasion of the reform of the entire JAEA organization in 2014, JAEA identified three important remaining issues on the geoscientific research program based on the synthesized latest results of research and development (R&D): "Development of countermeasure technologies for reducing groundwater inflow", "Development of modeling technologies for mass transport" and "Development of drift backfilling technology". The R&D on three remaining important issues have been carrying out in the MIU Project. This report summarizes the R&D activities planned for fiscal year 2019 on the basis of the MIU Master Plan updated in 2015 and Investigation Plan for the Third Medium to Long-term Research Phase.

JAEA Reports

Study on effects of coupled phenomenon on long-term behavior for crystalline rock in fiscal year 2017 and 2018 (Joint research)

Ichikawa, Yasuaki*; Kimoto, Kazushi*; Matsui, Hiroya

JAEA-Research 2019-005, 32 Pages, 2019/10

JAEA-Research-2019-005.pdf:6.13MB

It is important to evaluate the mechanical stability around the geological repository for high-level radioactive waste, during not only the design, construction and operation phases, but also the post-closure period over several millennia. The rock mass around the tunnels could be deformed in response to time dependent behaviors such as creep and stress relaxation. Therefore, this study has started as a joint research with Okayama University from 2016. This report summarize the results of the joint research performed in fiscal year 2017 and 2018. Based on the research results obtained in fiscal year 2016, automatic measurement system was developed, which can collect very large data on surface elastic wave propagation in a short time, also the applicability of various kinds of parameters derived from measured elastic wave data was examined.

JAEA Reports

Study on the applicability of the fiber-optic crack detection sensor as a safety technology (FY2015-FY2018) (Joint research)

Kono, Masaru*; Hayama, Kazunori*; Matsui, Hiroya; Ozaki, Yusuke

JAEA-Technology 2019-011, 35 Pages, 2019/07

JAEA-Technology-2019-011.pdf:2.65MB

To verify long-term safety performance of the sensor for decades, we decided the extension of the collaborative research and the evaluation test of long-term durability of fiber-optic crack detection sensor developed by Tokyo Measuring Instruments Laboratory Co., Ltd. at the Mizunami Underground Research Laboratory were continued from FY 2015 to FY 2018. As a result, the measurement system using of the fiber-optic crack detection sensor is applicable for long-term measurement in deep underground area and find the future subject.

JAEA Reports

Mizunami Underground Research Laboratory Project, Annual report for fiscal year 2017

Takeuchi, Ryuji; Iwatsuki, Teruki; Matsui, Hiroya; Nohara, Tsuyoshi; Onoe, Hironori; Ikeda, Koki; Mikake, Shinichiro; Hama, Katsuhiro; Iyatomi, Yosuke; Sasao, Eiji

JAEA-Review 2019-005, 76 Pages, 2019/06

JAEA-Review-2019-005.pdf:24.91MB

The Mizunami Underground Research Laboratory (MIU) project is being pursued by the Japan Atomic Energy Agency (JAEA) to enhance the reliability of geological disposal technologies through investigations of the deep geological environment in the crystalline rock (granite) at Mizunami City, Gifu Prefecture, central Japan. On the occasion of the research program and management system revision of the entire JAEA organization in 2014, JAEA identified three remaining important issues on the geoscientific research program based on the latest results of the synthesizing research and development: "Development of countermeasure technologies for reducing groundwater inflow", "Development of modeling technologies for mass transport" and "Development of drift backfilling technologies". The research and development on three remaining important issues have been carrying out on the MIU project. In this report, the current status of the research and development activities and construction in fiscal year 2017 is summarized.

JAEA Reports

Planning for in-situ backfilling test to the gallery in the Mizunami Underground Research Laboratory

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".

Journal Articles

Crack expansion and fracturing mode of hydraulic refracturing from Acoustic Emission monitoring in a small-scale field experiment

Ishida, Tsuyoshi*; Fujito, Wataru*; Yamashita, Hiroto*; Naoi, Makoto*; Fujii, Hirokazu*; Suzuki, Kenichiro*; Matsui, Hiroya

Rock Mechanics and Rock Engineering, 52(2), p.543 - 553, 2019/02

AA2017-0694.pdf:2.54MB

 Times Cited Count:14 Percentile:68.19(Engineering, Geological)

We pressurized and injected water in a hole drilled downward from a floor of the 500 m level gallery in MIU, central Japan. Acoustic emissions (AEs) monitored with 16 sensors in four boreholes located 1 m away from the HF hole exhibited two-dimensional distributions, which likely delineate a crack induced by the fracturing. Expansions of the regions in which AEs occurred were observed only immediately after the first and second BDs. Many AE events in other periods were distributed within the regions where AE events had already occurred. The initial motion polarities of P-waves indicate that tensile-dominant AE events occurred when the regions expanded and they were distributed primarily on the frontiers of the regions where AE events had already occurred. The experimental results suggest that increasing the injection flow rate is effective for generating new cracks in the refracturing, with the new crack expansions being induced by tensile fracturing.

Journal Articles

Estimation on the change of the condition of the impervious plug during groundwater recovery experiment

Matsui, Hiroya; Mikake, Shinichiro; Ikeda, Koki; Tsutsue, Jun

Dai-46-Kai Gamban Rikigaku Ni Kansuru Shimpojiumu Koenshu (CD-ROM), p.286 - 291, 2019/01

Japan Nuclear Energy Agency (JAEA) has been conducting the groundwater recovery experiment to develop a methodology to estimate the geological environment recovery after closure of the drift at GL-500m in Mizunami Underground Research Laboratory, Japan. For the experiment, an impervious concrete plug was constructed to maintain a recovered water pressure and its functions were assessed based on the monitoring results and interpretation of several kinds of measurements performed inside and outside of the plug during groundwater recovery test. This report summarized the change of the condition of the plug due to groundwater recovery estimated based on the different kinds of monitoring data.

JAEA Reports

Mizunami Underground Research Laboratory Project, Plan for fiscal year 2018

Takeuchi, Ryuji; Iwatsuki, Teruki; Matsui, Hiroya; Ikeda, Koki; Mikake, Shinichiro; Hama, Katsuhiro; Iyatomi, Yosuke; Sasao, Eiji

JAEA-Review 2018-019, 29 Pages, 2018/12

JAEA-Review-2018-019.pdf:6.16MB

The Mizunami Underground Research Laboratory (MIU) Project is being pursued by the Japan Atomic Energy Agency (JAEA) to enhance the reliability of geological disposal technologies through investigations of the deep geological environment in the crystalline host rock (granite) at Mizunami, Gifu Prefecture, central Japan. On the occasion of the reform of the entire JAEA organization in 2014, JAEA identified three important issues on the geoscientific research program: "Development of countermeasure technologies for reducing groundwater inflow", "Development of modelling technologies for mass transport" and "Development of drift backfilling technology", based on the latest results of the synthesizing research and development (R&D). The R&D on three remaining important issues have been carrying out on the MIU Project. This report summarizes the R&D activities planned for fiscal year 2018 on the basis of the MIU Master Plan updated in 2015 and Investigation Plan for the Third Medium to Long-term Research Phase.

JAEA Reports

Study on crystalline rock aiming at evaluation method of long-term behavior of rock mass, 2 (Joint research)

Fukui, Katsunori*; Hashiba, Kimihiro*; Matsui, Hiroya

JAEA-Research 2018-006, 57 Pages, 2018/10

JAEA-Research-2018-006.pdf:2.99MB

It is important to evaluate the stability of a repository for high-level radioactive waste not only during the design, construction and operation phases, but also during the post-closure period, for time frames likely exceeding several millennia or longer. The rock mass around the tunnels could be deformed through time in response to time dependent behavior. In view of above points, this study has been started as a collaboration study with the University of Tokyo from FY2016. In the FY2017, the creep test of Tage tuff was continuously conducted and reached its twentieth year. The overview of the test was described, and the phenomenological aspects and the mechanisms of the creep of tuff were discussed with comparing the long- and short-term creep tests. The effects of loading rate and water content on rock strength were examined under various water conditions. The variable-compliance-type constitutive model was modified to reproduce those under uniaxial tension.

JAEA Reports

Development of groundwater management technology report

Iyatomi, Yosuke; Mikake, Shinichiro; Matsui, Hiroya

JAEA-Review 2018-004, 42 Pages, 2018/03

JAEA-Review-2018-004.pdf:4.71MB

The Mizunami Underground Research Laboratory (MIU) project is being pursued by the Japan Atomic Energy Agency (JAEA) to enhance the reliability of geological disposal technologies through investigations of the deep geological environment in the crystalline host rock (granite) at Mizunami City in Gifu Prefecture, central Japan. The three remaining important issues have been carrying out on the MIU project. This report focuses on "Development of groundwater management technology" for "Development of countermeasure technologies for reducing groundwater inflow", which is one of those important issues. The concentrations of naturally occurring fluorine and boron dissolved in groundwater pumped from shafts and horizontal tunnels at MIU, are reduced to the levels below the environmental standards at a water treatment facility. The development of groundwater management technologies including such groundwater treatment is one key issue for large-scale underground facility construction. With this background, literature survey related to investigations on the latest treatment technologies for removing fluorine and boron from waste water were conducted and applicability of the technologies to MIU were reviewed. Additionally, the countermeasures against rocks, soils and groundwater containing naturally occurring heavy metals were summarized. The literature survey results indicated that the adsorbent was able to remove fluorine and boron, and the coprecipitation was able to remove fluorine to the levels below their respective environmental standards. However, the ground water at MIU contains suspended solids and cement due to excavation, its removal rates of fluorine and boron are different from the ones of general waste water. From this point, it concluded that the present groundwater treatment method performed at MIU: coagulation treatment for removal of fluorine and control of pH primary, and adsorbent treatment for removed boron is appropriated.

Journal Articles

Evaluation of combined pre- and post-excavation grouting for reducing water inflow under high water pressure condition

Mikake, Shinichiro; Ikeda, Koki; Matsui, Hiroya; Tsuji, Masakuni*; Nishigaki, Makoto*

Doboku Gakkai Rombunshu, C (Chiken Kogaku) (Internet), 74(1), p.76 - 91, 2018/03

Pre-grouting of shafts and galleries had been conducted during the construction of MIU in the aspect of reducing water inflow. After excavating GL.-500m gallery, a post-grouting was performed on section of the pre-excavation grouting area under high water pressure condition (max: 4MPa). The post-grouting experiment was performed outside of the pre-grouting zone with designs, applying colloidal silica grouting material and complex dynamic grouting. It was estimated that the inflow after post-grouting was reduced by 1/100 of the case that pre- and post-grouting were not performed. These results indicate that the applied combined pre- and post-grouting methodology is effective in reducing water inflow and it can be applicable under high water pressure condition. Then, this paper states the theoretical evaluation of relationship between reduction of hydraulic conductivity and the grouting zone is very convenient and useful for grouting design and estimate of water inflow.

JAEA Reports

Mizunami Underground Research Laboratory Project, Annual report for fiscal year 2016

Ishibashi, Masayuki; Hama, Katsuhiro; Iwatsuki, Teruki; Matsui, Hiroya; Takeuchi, Ryuji; Nohara, Tsuyoshi; Onoe, Hironori; Ikeda, Koki; Mikake, Shinichiro; Iyatomi, Yosuke; et al.

JAEA-Review 2017-026, 72 Pages, 2018/01

JAEA-Review-2017-026.pdf:18.23MB

The Mizunami Underground Research Laboratory (MIU) project is being pursued by the Japan Atomic Energy Agency (JAEA) to enhance the reliability of geological disposal technologies through investigations of the deep geological environment in the crystalline host rock (granite) at Mizunami, Gifu Prefecture, central Japan. On the occasion of the research program and management system revision of the entire JAEA organization in 2014, JAEA identified three important issues on the geoscientific research program: "Development of countermeasure technologies for reducing groundwater inflow", "Development of modeling technologies for mass transport" and "Development of drift backfilling technologies", based on the latest results of the synthesizing research and development (R&D). The R&D on three important issues have been carrying out on the MIU project. In this report, the current status of R&D activities and construction in 2016 is summarized.

Journal Articles

Rock grouting technology for reducing groundwater inflow in deep underground

Tsuji, Masakuni*; Ikeda, Koki; Mikake, Shinichiro; Matsui, Hiroya

Tunnelling Activities in Japan 2018, P. 23, 2018/00

We have recently conducted pre- and post-grouting works at a gallery in 500m depth of MIU. The groundwater pressure was maximum 4.0MPa. As a result, water ingress was reduced to a one-hundredth of an assumed amount with no grouting were performed, which is reduction from approx. Moreover, after a later post-grouting work repeated in the most wet section of the relevant gallery, all dripping spots turned out to be lower than 1 L/min. Especially for the post-grouting technologies, three new concepts were demonstrated and found to be effective; which is the Colloidal silica grout for a new material, Complex dynamic grouting method for a new injection method, and sealing outer area of pre-grouted zones for a new grouting area as design concepts.

294 (Records 1-20 displayed on this page)