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Journal Articles

Fabrication of a novel magnetic topological heterostructure and temperature evolution of its massive Dirac cone

Hirahara, Toru*; Otrokov, M. M.*; Sasaki, Taisuke*; Sumida, Kazuki*; Tomohiro, Yuta*; Kusaka, Shotaro*; Okuyama, Yuma*; Ichinokura, Satoru*; Kobayashi, Masaki*; Takeda, Yukiharu; et al.

Nature Communications (Internet), 11, p.4821_1 - 4821_8, 2020/09

 Times Cited Count:11 Percentile:89.19(Multidisciplinary Sciences)

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

Evaluation of photocatalytic abilities by variation of conductivity and dimethyl sulfoxide; Photocatalytically active TiO$$_{2}$$-coated wire mesh prepared via a double-layer coating method

Mori, Masanobu*; Sugita, Tsuyoshi; Fujii, Kengo*; Yamazaki, Taiki*; Isaka, Mayu*; Kobayashi, Kentaro*; Iwamoto, Shinji*; Itabashi, Hideyuki*

Analytical Sciences, 34(12), p.1449 - 1453, 2018/12

 Times Cited Count:1 Percentile:6.01(Chemistry, Analytical)

The photocatalyst coating stainless-steel wire mesh (TiO$$_{2}$$-WM) was prepared by double-layer coating method. The TiO$$_{2}$$-WM was evaluated using flow analytical system, which included the reactor and conductimetric detector (FAS-CD). The DMSO decomposition test through the FAS-CD reveal that photocatalytst was stable coating on the stainless-steel wire mesh.

Journal Articles

AMS radiocarbon age of the Kurodake pyroclastic-flow deposit in Kuju volcanic group, SW Japan

Okuno, Mitsuru*; Nagaoka, Shinji*; Kokubu, Yoko; Nakamura, Toshio*; Kobayashi, Tetsuo*

Fukuoka Daigaku Rigaku Shuho, 48(1), p.1 - 5, 2018/03

Kuju volcanic group, located in central Kyushu, Japan, consists of over twenty volcanoes (lava domes as well as small stratovolcanoes). The Kurodake is largest lava dome with a volume of 1.6 km$$^{3}$$, and generated Kurodake pyroclastic-flow (Kj-Kd) and ash-fall (Kj-KdA) deposits. To refine age of the Kurodake eruption, we conducted radiocarbon dating of a charcoal fragment in the Kj-Kd with an AMS system at Tono Geoscience Center, JAEA. The obtained $$^{14}$$C date, 1505$$pm$$40 BP, can correspond to 1310-1423 cal BP (probability= 74.6%), 1430-1442 cal BP (2.4%) and 1456-1521 cal BP (23.0%) in 2$$sigma$$ confidence level. The medium probability date, 1391 cal BP, is consistent with the stratigraphy and gives the reliable age for the Kj-Kd.

JAEA Reports

Study on engineering technologies in the Mizunami Underground Research Laboratory (FY 2015); Development of design and construction planning and countermeasure technologies (Contract research)

Toguri, Satohito*; Kobayashi, Shinji*; Tsuji, Masakuni*; Yahagi, Ryoji*; Yamada, Toshiko*; Matsui, Hiroya; Sato, Toshinori; Mikake, Shinichiro; Aoyagi, Yoshiaki

JAEA-Technology 2017-005, 43 Pages, 2017/03

JAEA-Technology-2017-005.pdf:4.4MB

The study on engineering technology in the Mizunami Underground Research Laboratory (MIU) project roughly 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 and mitigating of the excavation effect. In FY2015, as a part of the important issues on the research program, water-tight grouting method has been developed. Grouting methods utilized in the MIU were evaluated and the post-excavation grouting at the -500m Access/Research Gallery-South was planned based on these evaluation results. Also, technology development from the viewpoint of geological disposal was summarized, and information on the alternative method to the grouting method was collected and organized.

Journal Articles

Post-grouting experiences for reducing groundwater inflow at 500 m depth of the Mizunami Underground Research Laboratory, Japan

Tsuji, Masakuni*; Kobayashi, Shinji*; Mikake, Shinichiro; Sato, Toshinori; Matsui, Hiroya

Procedia Engineering, 191, p.543 - 550, 2017/00

 Times Cited Count:9 Percentile:94.12

This paper shows the application of two post-grouting works to a gallery at 500 m depth of Mizunami Underground Research Laboratory in Japan. Three new grouting concepts were applied to the post-grouting works; a new grout material, a new injection system, and a new post-grouting zone. As for a grout material, "durable liquid-type colloidal silica grout (CSG)" was applied to seal the narrow fractures. As for an injection system, "complex dynamic grouting method" was applied to improve the penetrability of the grout material. The grouting works were successful in reducing the abundant water inflow from the rock mass with many fractures.

Journal Articles

AMS radiocarbon dates of pyroclastic-flow deposits on the southern slope of the Kuju Volcanic Group, Kyushu, Japan

Okuno, Mitsuru*; Nagaoka, Shinji*; Kokubu, Yoko; Nakamura, Toshio*; Kobayashi, Tetsuo*

Radiocarbon, 59(2), p.483 - 488, 2017/00

 Times Cited Count:3 Percentile:21.86(Geochemistry & Geophysics)

We present here results of AMS $$^{14}$$C dating to refine the history of the middle and western parts of the Kuju Volcanic Group, located in middle Kyushu, Japan, which consists of more than 20 lava domes and cones. $$^{14}$$C dating has conducted by AMS (JAEA-AMS-TONO) under the Common-Use Facility Program of JAEA. The Handa PF deposits, which are products of the largest eruption of the group, were dated to $$sim$$53.5 ka BP. The Shirani and Muro PF deposits, which are block-and-ash flows, were dated to 44 to $$>$$50 cal ka BP and 35$$sim$$39 cal ka BP, respectively. These ages can be correlated with the TL ages for the lava domes. Therefore, both TL and $$^{14}$$C methods can be useful tools in establishing the eruptive sequence of lava domes and pyroclastic flows. This study also demonstrates that these eruptive activities occurred after the Handa pfl, the biggest eruption during the last 150 kyrs without a significant time interval.

Journal Articles

Post-grouting with colloidal silica at great depth of the Mizunami Underground Research Laboratory, Japan

Tsuji, Masakuni*; Kobayashi, Shinji*; Sato, Toshinori; Mikake, Shinichiro; Matsui, Hiroya

Proceedings of 8th Nordic Grouting Symposium, p.171 - 185, 2016/09

This paper presents the application of a durable liquid-type colloidal silica grout (CSG), to the great depth of the Mizunami Underground Research Laboratory (MIU). The CSG had been invented decades ago in Japan for the purpose of the ground improvement. A post-grouting experiment with the CSG carried out in 300 m depth of MIU confirmed its applicability and good durability at a great depth more than 3 years. Furthermore, a comparison study of applying the CSG between this experiment and a Swedish project indicated good applicability of the Swedish theoretical design to MIU. The CSG with the Swedish design were applied to the post-grouting campaign in a gallery at 500 m depth for further reducing water ingress and for developing the latest grouting methodology. The grouting was successful in reducing the abundant inflow from the rock with many fractures. The conductivity of the grouted rock mass of the latter fans is estimated to be lower than 10$$^{-9}$$ m/s.

JAEA Reports

Three-dimensional stress analysis of reflooding tunnel during submerging process using crack tensor model at Mizunami Underground Research Laboratory

Ozaki, Yusuke; Matsui, Hiroya; Kuwabara, Kazumichi; Tada, Hiroyuki*; Sakurai, Hideyuki*; Kumasaka, Hiroo*; Goke, Mitsuo*; Kobayashi, Shinji*

JAEA-Research 2016-007, 125 Pages, 2016/06

JAEA-Research-2016-007.pdf:34.66MB

In Mizunami Underground Research Laboratory (MIU), the stress analysis of fractured rock have been performed with crack tensor model. In MIU, a reflooding test is performed at 500m stage. In this study, stress analysis of rock during submerging process of the tunnel is performed by using crack tensor model. The deformation of the rock under different water levels in the tunnel is simulated. The stress condition by high pressure due to inflow of groundwater into tunnel is also estimated. These simulation are performed under assumption that groundwater does not permeate into rock for the estimation of maximum pressure acting on the rock. The stress analysis with consideration of permeation of groundwater into rock is also conducted for the estimation of stress condition after the diffusion of water pressure in tunnel. The results of these analyses lead the conclusion that the pressure of the rock reaches the groundwater pressure near the face of tunnel when the tunnel is submerged.

JAEA Reports

Study on engineering technologies in the Mizunami Underground Research Laboratory (FY 2014); Development of design and construction planning and countermeasure technologies (Contract research)

Kobayashi, Shinji*; Niimi, Katsuyuki*; Tsuji, Masakuni*; Yamada, Toshiko*; Aoyagi, Yoshiaki; Sato, Toshinori; Mikake, Shinichiro; Osawa, Hideaki

JAEA-Technology 2015-039, 170 Pages, 2016/02

JAEA-Technology-2015-039.pdf:37.73MB

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. For the characteristics of earthquake ground motion, measurement data obtained by seismometers installed in the Mizunami Underground Laboratory were analyzed, and the comprehensive assessment of the relationship between the measurement data and the geological condition at each depth was performed. As for "Study on grouting method at deep underground ", post grouting was carried out and evaluated based on the Construction plan in FY2013. Furthermore, target of the future R&D was proposed.

Journal Articles

$$^{61}$$Ni synchrotron radiation-based M$"o$ssbauer spectroscopy of nickel-based nanoparticles with hexagonal structure

Masuda, Ryo*; Kobayashi, Yasuhiro*; Kitao, Shinji*; Kurokuzu, Masayuki*; Saito, Makina*; Yoda, Yoshitaka*; Mitsui, Takaya; Hosoi, Kohei*; Kobayashi, Hirokazu*; Kitagawa, Hiroshi*; et al.

Scientific Reports (Internet), 6, p.20861_1 - 20861_8, 2016/02

 Times Cited Count:6 Percentile:37.08(Multidisciplinary Sciences)

Journal Articles

Post-excavation grouting new design, results and evaluation of a gallery at great depth in Mizunami Underground Research Laboratory

Tsuji, Masakuni*; Kobayashi, Shinji*; Sato, Toshinori; Mikake, Shinichiro

Dai-44-Kai Gamban Rikigaku Ni Kansuru Shimpojiumu Koenshu (CD-ROM), p.359 - 364, 2016/01

Pre-excavation grouting of shafts and galleries has been conducted during the construction of Mizunami Underground Research Laboratory in the aspect of safe works and reducing the discharge treatment of the water inflow. The grouting methodology has been simultaneously studied and developed as there is less experience of grouting in low conductive rock with high water pressure, especially in Japan. After excavating GL.-500m gallery on the ventilation shaft side, a post-excavation grouting campaign was performed on a 16-meter section of the pre-grouted area. Three new options for the grouting design were adopted and found to be effective with sufficiently decreasing the water inflow into the gallery.

Journal Articles

Grouting for reducing groundwater inflow into a gallery at 500m depth of the Mizunami Underground Research Laboratory, Japan

Tsuji, Masakuni*; Kobayashi, Shinji*; Sato, Toshinori; Mikake, Shinichiro

Proceedings of the ISRM Regional Symposium EUROCK 2015 & 64th Geomechanics Colloquium; Future Development of Rock Mechanics, p.35 - 41, 2015/10

Rock grouting has been an essential measure to reduce water ingress into the deep underground during the excavation of Mizunami Underground Research Laboratory project in Japan. This paper shows an overview of grouting works performed at a gallery of 120 m at 500 m depth. After completion of its excavation with the pilot borehole investigation and pre-grouting mainly by Super-fine Portland cement, the inflow from the whole gallery was 200-220 Liter/min within the requirement. Then, at a limited section of 16 m, post-grouting was performed with new designs, applying colloidal silica grout, complex dynamic grouting, and grouting outside of the pregrouted zone. These designs were effective and the inflow at the section reduced from 35 to 11 Liter/min. These experiences must be fruitful for advancing the present technology and there should have been potential for reducing further inflow if any of the new designs are applied from the pre-grouting phase.

Journal Articles

Excavation cycle times recorded during sinking of a deep shaft in crystalline rock; A Case example at ventilation shaft of Mizunami URL, Japan

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:3 Percentile:20.28(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.

JAEA Reports

Three-dimensional excavation analysis based on crack tensor model at the Mizunami Underground Research Laboratory

Takayama, Yusuke; Sato, Toshinori; Sanada, Hiroyuki; Tada, Hiroyuki*; Kumasaka, Hiroo*; Fukuda, Tsuyoshi*; Kobayashi, Shinji*

JAEA-Research 2015-003, 102 Pages, 2015/07

JAEA-Research-2015-003.pdf:20.21MB

In the rock mechanical study in the Mizunami Underground Research Laboratory Project, the development of the evaluation method for the excavation damaged zone due to excavation of shafts and research galleries is one of the important issues. In this study, three-dimensional excavation analysis is conducted. Crack tensor used in these analysis were measured using the data collected in wall surface observation in study tunnels such as the horizontal tunnels to a depth of 500 m. The results of analysis were compared with existing measurements at a depth of 500 m obtained using in-situ strain meters. The excavation analysis using crack tensor and initial stress obtained from the Phase I and Phase II were carried out to examine the influence of crack tensor and initial stress on the results of analysis.

Journal Articles

One-dimensional analysis of ECRH-assisted plasma start-up in JT-60SA

Hada, Kazuyoshi*; Nagasaki, Kazunobu*; Masuda, Kai*; Kobayashi, Shinji*; Ide, Shunsuke; Isayama, Akihiko; Kajiwara, Ken

Fusion Science and Technology, 67(4), p.693 - 704, 2015/05

 Times Cited Count:6 Percentile:48.17(Nuclear Science & Technology)

no abstracts in English

Journal Articles

Attempt to measure magnetic hyperfine fields in metallic thin wires under spin Hall conditions using synchrotron-radiation M$"o$ssbauer spectroscopy

Mibu, Ko*; Mitsui, Takaya; Tanaka, Masaaki*; Masuda, Ryo*; Kitao, Shinji*; Kobayashi, Yasuhiro*; Yoda, Yoshitaka*; Seto, Makoto*

Journal of Applied Physics, 117(17), p.17E126_1 - 17E126_4, 2015/05

 Times Cited Count:2 Percentile:11.36(Physics, Applied)

JAEA Reports

Study on engineering technologies in the Mizunami Underground Research Laboratory (FY 2013); Development of design and construction planning and countermeasure technologies (Contract research)

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.

Journal Articles

Pre-excavation grouting design, results and evaluation of a gallery at great depth in Mizunami Underground Research Laboratory

Tsuji, Masakuni*; Kobayashi, Shinji*; Sato, Toshinori; Mikake, Shinichiro

Dai-43-Kai Gamban Rikigaku Ni Kansuru Shimpojiumu Koenshu (CD-ROM), p.7 - 12, 2015/01

Pre-excavation grouting of shafts and galleries has been conducted during the construction of Mizunami Underground research laboratory in the aspect of safe works and reducing the discharge treatment of the water inflow. The grouting methodology has been simultaneously studied an developed as there is less experience of grouting in low conductive rock with high water pressure, especially in Japan. Ahead of excavating GL.-500m gallery on the ventilation shaft side, grouting design was performed based on the estimation of water inflow by the pilot-boring investigations and the design was properly revised during the campaign. The gallery satisfied the inflow requirement with good sealing effect.

Journal Articles

Analysis of excavation cycle time during sinking of the ventilation shaft at the Mizunami Underground Research Laboratory

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.

81 (Records 1-20 displayed on this page)