Long term monitoring and evaluation of the excavation damaged zone induced around the wall of the shaft applying optical fiber sensor (Cooperative research)

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.

Adefining the mechanism of the gas-bubble AE characteristics by two-phase flow test

Niunoya, Sumio*; Hata, Koji*; Uyama, Masao*; Aoyagi, Kazuhei; Tanai, Kenji

Dai-47-Kai Gamban Rikigaku Ni Kansuru Shimpojiumu Koenshu (Internet), p.92 - 97, 2020/01

Since underground water at the Horonobe Underground Research Laboratory site includes the dissolved gas, it is important to understand the quantitative behavior of AE signal waveform clearly and to develop the criteria of sorting technique. In this report, we tried to perform two types of laboratory tests (Small pipe test and Flat-plate test) in order to obtain detail data of AE signal wave form under two-phase flow. As the result, we could understand that there exists the relationship between the pressure breathing and AE generation, and that the diameter of pipe did not affect the AE behavior.

The In-situ experiment for performance confirmation of engineered barrier system at Horonobe Underground Research Laboratory; Consideration of concrete-type plug composition

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.

In situ stress measurement at the 350 m Loop Gallery East at the Horonobe Underground Research Laboratory

Aoyagi, Kazuhei; Sakurai, Akitaka; Niunoya, Sumio*

JAEA-Data/Code 2016-022, 91 Pages, 2017/03

JAEA-Data-Code-2016-022.pdf:7.3MB
JAEA-Data-Code-2016-022-appendix(CD-ROM).zip:232.99MB

The objective of this report is to investigate the three dimensional stress state in the 350 m Loop Gallery (East) at the Horonobe Underground Research Laboratory. For the measurement, three boreholes, which are 17.0 m in length, were drilled. Hydraulic fracturing was applied as a stress measurement method. For the analysis, shut-in pressure of a transverse fractures, reopening pressure of longitudinal fractures and stress condition causing borehole breakouts were integrated into the equation; then stress state was calculated by inversion technique. As a result, considering the stress condition causing breakouts, the value of the maximum principal stress was 3.73 MPa, which is much smaller than the overburden pressure (about 6.0 MPa). The orientation of the maximum horizontal stress is almost vertical. The stress state is normal faulting.

The In-situ experiment for performance confirmation of engineered barrier system at Horonobe Underground Research Laboratory; Production of casing drilling machine for large dimeter pit, simulated overpack, buffer material blocks and backfilling materials

Nakayama, Masashi; Matsuzaki, Tatsuji*; Niunoya, Sumio*

JAEA-Research 2016-010, 57 Pages, 2016/08

JAEA-Research-2016-010.pdf:10.81MB
JAEA-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.

Evaluation of EDZ (Excavated Damage Zone) by multi-optical measurement probe in Horonobe Underground Research Center

Hata, Koji*; Niunoya, Sumio*; Aoyagi, Kazuhei; Fujita, Tomoo

Dai-44-Kai Gamban Rikigaku Ni Kansuru Shimpojiumu Koenshu (CD-ROM), p.319 - 324, 2016/01

Long-term monitoring and EDZ (Excavated Damage Zone) evaluation is carried out by this multi-optical measurement probe in the depth of 350m vertical shaft of Horonobe Underground Research Center project of the Japan Atomic Energy Agency. We have developed a multi-optical measurement probe incorporating an optical AE sensor, an optical water pressure sensor and an optical temperature sensor. Result of the measurement of AE, water pressure and temperature, it was made clear the influence of the shaft excavation. And from the source location analysis, it was found EDZ was less than 1.5m from shaft wall.

In situ stress measurements at the 350m pumping station in the Horonobe Underground Research Laboratory

Aoyagi, Kazuhei; Sakurai, Akitaka; Niunoya, Sumio*

JAEA-Data/Code 2015-010, 190 Pages, 2015/10

JAEA-Data-Code-2015-010.pdf:18.7MB
JAEA-Data-Code-2015-010-appendix(CD-ROM).zip:127.68MB

The objective of this report is to investigate the three dimensional stress state in the 350m pumping station at the Horonobe Underground Research Laboratory. For the measurement, four boreholes were drilled; three 20.0m long boreholes and one 6.0m long borehole. Hydraulic fracturing was applied as a stress measurement method. For the analysis, shut-in pressure of a transverse fractures, reopening pressure of longitudinal fractures and stress condition causing borehole breakouts were integrated into the equation; then stress state was calculated by inversion technique. As a result, considering the stress condition causing breakouts, the value of the maximum principal stress was 12 MPa, two times larger than overburden pressure. Furthermore, the ratio between maximum to minimum principal stress was 6. On the other hand, without considering the stress condition causing breakout, the maximum principal stress was 6 MPa; almost same as overburden pressure; the ratio between maximum to minimum principal stress was 2.7, thus the result was almost coincide with the result of surface-based investigation. The orientation of the maximum principal stress was N30W, dipping 45 from vertical axis.

In situ stress measurement at the 250m Niche off the South Shaft No.1 in the Horonobe Underground Research Laboratory

Aoyagi, Kazuhei; Sakurai, Akitaka; Niunoya, Sumio*

JAEA-Data/Code 2015-011, 182 Pages, 2015/09

JAEA-Data-Code-2015-011.pdf:33.41MB
JAEA-Data-Code-2015-011-appendix(CD-ROM).zip:41.95MB

The objective of this report is to investigate the three dimensional stress state in the 250 m Niche off the South Shaft No.1 at the Horonobe Underground Research Laboratory. For the measurement, three 20.0m long boreholes were drilled. Hydraulic fracturing was applied as a stress measurement method. For the analysis, shut-in pressure of a transverse fractures, reopening pressure of longitudinal fractures and stress condition causing borehole breakouts were integrated into the equation; then stress state was calculated by inversion technique. As a result of the in situ stress state measurement around the experimental area, the orientation of the maximum principal stress is estimated to be between E-W and ENE-WSW, dipping almost horizontal direction. This result agrees well with the estimated orientation of the main principal stress, the location of the borehole wall breakouts in 10-E250-M01 and the orientation of the generated crack in 10-E250-M03. The value of the maximum principal stress was 3.97 MPa.

Initial stress measurement by hydraulic fracturing method in diatomaceous mudstone in the Horonobe Underground Research Laboratory

Kondo, Keiji; Tsusaka, Kimikazu; Inagaki, Daisuke; Sugita, Yutaka; Kato, Harumi*; Niunoya, Sumio*

Dai-13-Kai Iwa No Rikigaku Kokunai Shimpojiumu Koen Rombunshu (CD-ROM), p.583 - 588, 2013/01

no abstracts in English

Application feasibility study of an evaluation technology for long-term rock behavior; Coupled hydraulic and mechanical analyses to evaluate rock behavior of shaft in fault

Noda, Masaru*; Sato, Shin*; Niunoya, Sumio*; Hata, Koji*; Matsui, Hiroya; Mikake, Shinichiro

Dai-41-Kai Gamban Rikigaku Ni Kansuru Shimpojiumu Koenshu (CD-ROM), p.202 - 207, 2012/01

The main shaft of Mizunami URL is located in fault, and due to the geology hydrological anisotropy is observed. Lining deformation may cause by increase of lining stress with degradation of drain material or aquifer of changes in future. Therefore, study on evaluation method to predict the effect by water pressure change is needed. In this study, by implementing coupled hydraulic and mechanical analyses, validity of methods of analysis is considered as compared to measuring for hydrological anisotropy in the main shaft. According to the result of the study, water pressure dependency was not shown, but the main shaft behavior was simulated taking account of hydrological anisotropy. Also validity of methods of coupled hydraulic and mechanical analyses as deterioration prediction was confirmed.