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Journal Articles

Mechanical characteristics of rock segment for reducing amount of cement use and stability of drift tunnel

Tada, Hiroyuki*; Kumasaka, Hiroo*; Saito, Akira*; Nakaya, Atsushi*; Ishii, Takashi*; Fujita, Tomo; Sugita, Yutaka; Nakama, Shigeo; Sanada, Masanori*

Doboku Gakkai Rombunshu, F2 (Chika Kukan Kenkyu) (Internet), 73(1), p.11 - 28, 2017/03

This study examined the mechanical characteristics of rock segments and backfill materials and analyzed the stability of the drift that is supported by the rock segments and gravel backfill. The results confirmed the technical aspects of the formation of the rock segments and the effectiveness of the planned efforts to further reduce the amount of cement used.

Journal Articles

Field test around Fukushima Daiichi Nuclear Power Plant site using improved Ce:Gd$$_{3}$$(Al,Ga)$$_{5}$$O$$_{12}$$ scintillator Compton camera mounted on an unmanned helicopter

Shikaze, Yoshiaki; Nishizawa, Yukiyasu; Sanada, Yukihisa; Torii, Tatsuo; Jiang, J.*; Shimazoe, Kenji*; Takahashi, Hiroyuki*; Yoshino, Masao*; Ito, Shigeki*; Endo, Takanori*; et al.

Journal of Nuclear Science and Technology, 53(12), p.1907 - 1918, 2016/12

 Times Cited Count:24 Percentile:96.18(Nuclear Science & Technology)

The Compton camera was improved for use with the unmanned helicopter. Increase of the scintillator array from 4$$times$$4 to 8$$times$$8 and expanse of the distance between the two layers contributed to the improvements of detection efficiency and angular resolution, respectively. Measurements were performed over the riverbed of the Ukedo river of Namie town in Fukushima Prefecture. By programming of flight path and speed, the areas of 65 m $$times$$ 60 m and 65 m $$times$$ 180 m were measured during about 20 and 30 minutes, respectively. By the analysis the air dose rate maps at 1 m height were obtained precisely with the angular resolution corresponding to the position resolution of about 10 m from 10 m height. Hovering flights were executed over the hot spot areas for 10-20 minutes at 5-20 m height. By using the reconstruction software the $$gamma$$-ray images including the hot spots were obtained with the angular resolution same as that evaluated in the laboratory (about 10$$^{circ}$$).

JAEA Reports

Laboratory testing of rock core samples from pre-excavation grouting area at Mizunami Underground Research Laboratory

Uyama, Masao*; Hitomi, Takashi*; Nakashima, Satoru*; Sato, Toshinori; Sanada, Hiroyuki; Aoyagi, Yoshiaki

JAEA-Research 2015-010, 67 Pages, 2015/10

JAEA-Research-2015-010.pdf:32.34MB
JAEA-Research-2015-010-appendix(CD-ROM).zip:528.25MB

Japan Atomic Energy Agency has been conducting a research project on (Grouting Technology Development for the Radioactive Waste Repository) funded by Ministry of Economy, Trade and Industry (METI), Japan. As a part of the project, various investigations were carried out in the -200m Refuge Niche where pre-excavation grouting was performed and the distribution of the injected grouting material, also the effectiveness of grouting penetration for reduction of groundwater inflow were confirmed As the continuation of these investigations, chemical influences of grouting material on the rock mass were determined through (Laboratory testing of rock core samples from pre-excavation grouting area at Mizunami Underground Research Laboratory). Specifically, core samples were obtained by check boring at where infiltration solidification of the grouting material was expected, and X-ray florescent analysis and Transmission Electron Microscope observation were performed focused on the contact parts of the grouting material and rock mass in fractures. As a result, the chemical influences of grouting material on the rock mass were identified.

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

Mizunami Underground Research Laboratory Project; Rock mechanical investigations at the -500m stage

Kuwabara, Kazumichi; Sato, Toshinori; Sanada, Hiroyuki; Takayama, Yusuke

JAEA-Research 2015-005, 378 Pages, 2015/07

JAEA-Research-2015-005.pdf:125.5MB
JAEA-Research-2015-005.zip:0.53MB

This report presents the results of following rock mechanical investigations conducted at the -500m Stage. (1) Laboratory tests using cores and block samples obtained at the -500m Stage. (2) In-situ stress measurement using Compact Conical-ended Borehole Overcoring (CCBO) method at the -500m Stage. (3) In-situ stress measurements using Differential Strain Curve Analysis(DSCA) method at the -500m Stage. (4) Development of rock mechanical model.

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.

JAEA Reports

Study on engineering technologies in the Mizunami Underground Research Laboratory (FY 2013); Development of recovery and mitigation technology on excavation damage (Contract research)

Fukaya, Masaaki*; Hata, Koji*; Akiyoshi, Kenji*; Sato, Shin*; Takeda, Yoshinori*; Miura, Norihiko*; Uyama, Masao*; Kaneda, Tsutomu*; Ueda, Tadashi*; Toda, Akiko*; et al.

JAEA-Technology 2014-040, 199 Pages, 2015/03

JAEA-Technology-2014-040.pdf:37.2MB

The researches on engineering technology in the Mizunami Underground Research Laboratory (MIU) project 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 for restoration and/or reduction of the excavation damage. The researches on engineering technology such as verification of the initial design were being conducted by using data measured during construction as a part of the second phase of the MIU plan. Examination about the plug for reflood test in the GL-500m Access/Research Gallery-North as part of the development of technologies for restoration and/or reduction of excavation damage were carried out. Specifically, Literature survey was carried out about the plug, based on the result of literature survey, examination of the design condition, design of the plug and rock stability using numerical simulation, selection of materials for major parts, and grouting for water inflow from between rock and plug, were carried out in this study.

JAEA Reports

Mizunami Underground Research Laboratory Project; Rock mechanical investigations annual report for fiscal year 2013

Sato, Toshinori; Sanada, Hiroyuki; Tanno, Takeo*

JAEA-Review 2014-049, 34 Pages, 2015/02

JAEA-Review-2014-049.pdf:26.38MB

This report presents the results of following rock mechanical investigations conducted in FY 2013. In-situ stress measurements using Compact Conical-ended Borehole Overcoring Technique were performed at the - 500m stage. Measurement system for rock mass displacement using optical fiber was installed at the - 500m stage as one of the reflooding test. Study on the modeling based on equivalent continuum model was continued. Phenomenological study and theoretical study on long-term behavior of crystalline rock were continued. Additionally, joint research, "Study on estimation of in-situ rock stress based on the results of various measurements" with Tokai University was also performed.

JAEA Reports

Study on effects of coupled phenomenon on long-term behavior for crystalline rock; FY2013 (Contract research)

Ichikawa, Yasuaki*; Kimoto, Kazushi*; Sato, Toshinori; Sanada, Hiroyuki; Kuwabara, Kazumichi

JAEA-Research 2014-027, 25 Pages, 2015/02

JAEA-Research-2014-027.pdf:16.92MB

The rock and the rock mass are known to show time-dependent behavior such as creep and the stress-relaxation. It is to evaluate long-term rock mechanics stability that the important theme understanding the property. From the research study until now, it is rock mechanics and chemical coupled phenomenon to have an influence on the long-term behavior. It is a theme to develop technique to model this coupled phenomenon, and to analyze. About an evaluation of the microcrack to have an influence on this coupled phenomenon, it is the theme that we should work on in a long-term rock mass behavior study chiefly. This study developed numerical analysis to check the ultrasonic scattering decrement behavior by the microcrack of the crystalline rock and the measurement technique. The FDTD method which modelled a crack was used for numerical analysis by split node. It depends on the simulation technique that it developed that useful knowledge was provided by elastic wave modeling. On the other hand, the ultrasonic measurement in a rock sample was measured by the water immersion method. As a result, we understood that we could acquire useful information to evaluate the scattering decrement of an elastic wave in a rock sample.

JAEA Reports

Mizunami Underground Research Laboratory Project, Annual report for fiscal year 2013

Hama, Katsuhiro; Mikake, Shinichiro; Nishio, Kazuhisa; Kawamoto, Koji; Yamada, Nobuto; Ishibashi, Masayuki; Murakami, Hiroaki; Matsuoka, Toshiyuki; Sasao, Eiji; Sanada, Hiroyuki; et al.

JAEA-Review 2014-038, 137 Pages, 2014/12

JAEA-Review-2014-038.pdf:162.61MB

Japan Atomic Energy Agency (JAEA) at Tono Geoscience Center (TGC) is pursuing a geoscientific research and development project namely the Mizunami Underground Research Laboratory (MIU) Project in crystalline rock environment in order to construct scientific and technological basis for geological disposal of High-level Radioactive Waste (HLW). The MIU Project has three overlapping phases: Surface-based Investigation phase (Phase I), Construction phase (Phase II), and Operation phase (Phase III). The MIU Project has been ongoing the Phase II and the Phase III in fiscal year 2013. This report presents the results of the investigations, construction and collaboration studies in fiscal year 2013, as a part of the Phase II and Phase III based on the MIU Master Plan updated in 2010.

JAEA Reports

Study on crystalline rock aiming at evaluation method of long-term behavior of rock mass; FY2013 (Contract research)

Fukui, Katsunori*; Hashiba, Kimihiro*; Sato, Toshinori; Sanada, Hiroyuki; Kuwabara, Kazumichi

JAEA-Research 2014-020, 50 Pages, 2014/11

JAEA-Research-2014-020.pdf:2.8MB

On the radioactive waste disposal, the long-term mechanical stability of shafts and galleries excavated in rock is required. Therefore, it is very important to understand the time-dependent behavior of rock mass for evaluating long-term mechanical stability. The purpose of this study is determining the mechanisms of time-dependent behavior of rock mass by precise testing, observation and measurement in order to develop methods for evaluating long-term mechanical stability of a rock mass. This report describes the results of the activities in fiscal year 2013. In Chapter 1, we described the overview and background of this study. In Chapter 2, the results of a long-term creep test on Tage tuff, started in fiscal year 1997 are described. In Chapter 3, the result of organization and analysis for time-dependent behavior of crystalline rock was described. In Chapter 4, for the drafting of in-situ test plan, examination of the numerical analysis technique of rock mass was carried out.

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.

Journal Articles

Groundwater recovery experiment using an underground gallery in fractured crystalline rock

Onoe, Hironori; Iwatsuki, Teruki; Saegusa, Hiromitsu; Onuki, Kenji; Takeuchi, Ryuji; Sanada, Hiroyuki; Ishibashi, Masayuki; Sato, Toshinori

Proceedings of 8th Asian Rock Mechanics Symposium (ARMS-8) (USB Flash Drive), 10 Pages, 2014/10

The selection of a geological disposal site for high-level radioactive waste (HLW) will be done taking into consideration performance of the geological environment. Geological environments would likely be influenced for several decades by changes due to the construction and operation of a large underground facility such as a HLW repository. Therefore, the post-closure recovery of the geological environment after backfilling of a facility is an important aspect for the safety assessment of geological disposal of HLW. With a focus on the hydraulic pressure and hydrochemical recovery processes around underground galleries in fractured crystalline rock, the groundwater recovery experiment will be conducted at the Mizunami Underground Research Laboratory to evaluate the natural groundwater and hydrochemical recovery of the rock mass. This paper provides an outline of the groundwater recovery experiment plan and progress of the supporting field investigations.

JAEA Reports

A Study on the method of an equivalent continuous body modelling using crack tensor theory in the Mizunami Underground Research Laboratory Project

Sanada, Hiroyuki; Sato, Toshinori; Tanno, Takeo*; Hikima, Ryoichi*; Tada, Hiroyuki*; Kumasaka, Hiroo*; Ishii, Takashi*; Sakurai, Hideyuki*

JAEA-Research 2014-006, 124 Pages, 2014/06

JAEA-Research-2014-006.pdf:11.26MB

Japan Atomic Energy Agency has been implementing the Mizunami Underground Research Laboratory (MIU) Project in order to develop the comprehensive investigation techniques for the geological environment and the engineering techniques to construct a deep underground laboratory in crystalline rock. In the rock mechanical study in the MIU 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 report, crack tensor was calculated using the tunnel wall mapping and rock mechanical test results in the shaft and research galleries in the MIU. Two dimension excavation analysis was conducted at the Ventilation Shaft and GL -500 m Sub Stage using the calculated crack tensor at GL -500 m. Based on calculated crack tensor at GL 500 m, validation of the crack tensor at GL -500 m estimated during Phase I was verified. Relative error of crack tensor was calculated in order to examine variation of relative error to the scale of observation areas.

JAEA Reports

Mizunami Underground Research Laboratory Project; Rock mechanical investigations annual report for fiscal year 2012

Sato, Toshinori; Tanno, Takeo*; Hikima, Ryoichi*; Sanada, Hiroyuki

JAEA-Review 2014-009, 60 Pages, 2014/05

JAEA-Review-2014-009.pdf:26.89MB

This report presents the following FY2012 activities undertaken to achieve the above goals. (1) In-situ stress measurements using Compact Conical-ended Borehole Overcoring Technique at the - 300m stage, (2) In-situ stress measurements using core-based methods at the - 500m stage, (3) Laboratory tests using core samples from boreholes drilled at the - 500m stage, (4) Study on the modeling based on equivalent continuum model, (5) Phenomenological study on long-term behavior, (6) Theoretical study for estimating long-term behavior, (7) Application of specific energy for evaluation of in-situ rock mass properties, (8) Study on estimation of in-situ rock stress based on the results of various measurements.

JAEA Reports

Theoretical study of rock for estimating long-term behavior; FY2012 (Contract research)

Ichikawa, Yasuaki*; Kimoto, Kazushi*; Sato, Toshinori; Tanno, Takeo; Hikima, Ryoichi; Sanada, Hiroyuki

JAEA-Research 2013-045, 69 Pages, 2014/03

JAEA-Research-2013-045.pdf:9.51MB

Rock mass is a complex material including several classes of discontinuities and inhomogeneous/anisotropic minerals. If observing rock samples, we know that crystalline rock is a complex of minerals, grain boundaries and microcracks. In this study, the series of experiments were managed by a flow-through type changing temperature, pH and applied stress. Attenuation of ultrasonic waves in rock is investigated experimentally using an intact but coarse-grained granite core sample. For ultrasonic measurements, piezoelectric transducers are used in a through-transmission mode. With the estimated response function, phase and amplitude spectra of the transmitted ultrasonic waves are investigated quantitatively to evaluate the attenuation and change in travel time.

JAEA Reports

Study of specific energy for evaluation of in situ rock mass properties (Joint research)

Hikima, Ryoichi*; Hirano, Toru*; Yamashita, Masayuki*; Ishiyama, Koji*; Tanno, Takeo*; Sanada, Hiroyuki; Sato, Toshinori

JAEA-Research 2013-040, 51 Pages, 2014/03

JAEA-Research-2013-040.pdf:6.86MB

For the research and development about high-level radioactive waste disposal, it is important to evaluate the mechanical stability of the excavation and the long-term behavior of in situ rock. However, from the limited information such as the bowling core before the excavation, it is difficult to evaluate the mechanical properties of in situ rock containing cracks. For this reason, evaluation of rock properties based on Specific Energy using mechanical data from an excavation machine is carried out. This report describes the results of the joint research carried out in FY 2010 to FY 2012.

JAEA Reports

Mizunami Underground Research Laboratory Project, Annual report for fiscal year 2012

Hama, Katsuhiro; Mikake, Shinichiro; Nishio, Kazuhisa; Matsuoka, Toshiyuki; Ishibashi, Masayuki; Sasao, Eiji; Hikima, Ryoichi*; Tanno, Takeo*; Sanada, Hiroyuki; Onoe, Hironori; et al.

JAEA-Review 2013-050, 114 Pages, 2014/02

JAEA-Review-2013-050.pdf:19.95MB

Japan Atomic Energy Agency (JAEA) at Tono Geoscience Center (TGC) is pursuing a geoscientific research and development project namely the Mizunami Underground Research Laboratory (MIU) Project in crystalline rock environment in order to construct scientific and technological basis for geological disposal of High-level Radioactive Waste (HLW). The MIU Project has three overlapping phases: Surface-based Investigation phase (Phase I), Construction phase (Phase II), and Operation phase (Phase III). The MIU Project has been ongoing the Phase II and the Phase III in fiscal year 2012. This report presents the results of the investigations, construction and collaboration studies in fiscal year 2012, as a part of the Phase II and Phase III based on the MIU Master Plan updated in 2010.

JAEA Reports

Mizunami Underground Research Laboratory Project; Rock mechanical investigations in situ stress measurements and laboratory tests using core on the GL.-300m and GL.-400m level of research galley

Tanno, Takeo*; Sato, Toshinori; Sanada, Hiroyuki; Hikima, Ryoichi*

JAEA-Research 2013-044, 257 Pages, 2014/02

JAEA-Research-2013-044.pdf:44.45MB

In the rock mechanical investigations, the research aims at "Characterization of geological environment in the Excavation Disturbed Zone (EDZ)" from the viewpoint of safety assessment. For the research, the specific data of the EDZ. The research also aims at "Characterization of geomechanical stability around tunnel " from the viewpoint of design and construction of underground facilities. This report presents the results of following rock mechanical investigations conducted at the GL.-300m and GL.-400m Level of Research Galley. (1) Laboratory tests using core and block samples obtained at the GL.-300m and GL.-400m Level of Research Galley, (2) Measurement of Compact Conical-ended Boerhole Overcoring (CCBO) method at the GL.-300m Level of Research Galley, (3) In-situ stress measurements using core-based methods at the GL.- 300m Stage.

JAEA Reports

Study on crystalline rock for evaluating method of long-term behavior; FY2012 (Contract research)

Fukui, Katsunori*; Hashiba, Kimihiro*; Tanno, Takeo; Hikima, Ryoichi; Sanada, Hiroyuki; Sato, Toshinori

JAEA-Research 2013-031, 52 Pages, 2013/12

JAEA-Research-2013-031.pdf:4.06MB

It is very important to understand the time-dependent behavior of rock for evaluating long-term mechanical stability. The purpose of this study is determining the mechanisms of time-dependent behavior of rock by the precise test, observation and measurement, to develop methods for evaluating long-term mechanical stability. This report describes the results of the activities in fiscal year 2012. In Chapter 1, we provide an overview and the background to this study. In Chapter 2, the results of a long-term creep test on Tage tuff, started in fiscal year 1997 are described. In Chapter 3, the experimental results concerning the loading-rate dependency of strength were examined to understand the time-dependency of rock. In Chapter 4, the stability of tunnels, around which rock stress is larger than that around a circular tunnel, were examined to obtain useful information on the future plan for ${it in-situ}$ tests in the underground research laboratory.

144 (Records 1-20 displayed on this page)