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JAEA Reports

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.

Journal Articles

Estimation of rock mass stress state based on convergence measurement during gallery excavation

Aoyagi, Kazuhei; Nago, Makito*; Kamemura, Katsumi*; Sugawara, Kentaro*

Proceedings of 9th Asian Rock Mechanics Symposium (ARMS-9) (USB Flash Drive), 10 Pages, 2016/10

JAEA Reports

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$$^{circ}$$ from vertical axis.

JAEA Reports

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

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

JAEA-Data/Code 2015-012, 171 Pages, 2015/09

JAEA-Data-Code-2015-012.zip:33.31MB
JAEA-Data-Code-2015-012.pdf:28.27MB

The objective of this report is to investigate the three dimensional stress state in the 250 m Niche off the West 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 was estimated to be ESE-WNW, dipping 70$$^{circ}$$ from the vertical axis. The orientation of the minimum principal stress was NEN-SWS, dipping 60$$^{circ}$$ from vertical axis. The orientation of the principal stresses is almost coincided with the direction of borehole breakouts and longitudinal crack induced in the boreholes. The values of the maximum and minimum principal stresses were 2.6 MPa and 2.1 MPa, respectively.

JAEA Reports

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.

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.

Journal Articles

Post irradiation plastic properties of F82H derived from the instrumented tensile tests

Taguchi, Tomitsugu; Jitsukawa, Shiro; Sato, Michitaka*; Matsukawa, Shingo*; Wakai, Eiichi; Shiba, Kiyoyuki

Journal of Nuclear Materials, 335(3), p.457 - 461, 2004/12

 Times Cited Count:10 Percentile:58.07(Materials Science, Multidisciplinary)

F82H (Fe-8Cr-2W) and its variant doped with 2%Ni were irradiated up to 20 dpa at 300$$^{circ}$$C in the High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory. Post irradiation tensile testing was performed at room temperature. During testing, the images of the specimens including the necked region were continuously recorded. Tests on cold worked material were also carried out for comparison. From the load-displacement curves and the strain distributions obtained from the images, flow stress levels and strain hardening behavior was evaluated. A preliminary constitutive equation for the plastic deformation of irradiated F82H is presented. The results suggest that the irradiation mainly causes defect-induced hardening while it did not strongly affect strain hardening at the same flow stress level for F82H irradiated at 300$$^{circ}$$C. The strain hardening of Ni doped specimens was, however, strongly affected by irradiation. Results provide basics to determine allowable stress levels at temperatures below 400$$^{circ}$$C.

JAEA Reports

Development of facility for in-situ observation during slow strain rate test for irradiated materials

Nakano, Junichi; Tsukada, Takashi; Tsuji, Hirokazu; Terakado, Shogo; Koya, Toshio; Endo, Shinya

JAERI-Tech 2003-092, 54 Pages, 2004/01

JAERI-Tech-2003-092.pdf:14.05MB

Irradiation assisted stress corrosion cracking (IASCC) is a degradation phenomenon caused by synergy of neutron radiation, aqueous environment and stress on in-core materials, and it is an important issue in accordance with increase of aged light water reactors. Isolating crack initiation stage from crack growth stage is very useful for the evaluation of the IASCC behavior. Hence facility for in-situ observation during slow strain rate test (SSRT) for irradiated material was developed. As performance demonstrations of the facility, tensile test with in-situ observation and SSRT without observation were carried out using unirradiated type 304 stainless steel in 561 K water at 9 MPa. The following were confirmed from the results. (1) Handling, observation and recording of specimen can be operated using manipulators in the hot cell. (2) In-situ observation can be performed in pressurized high temperature water and flat sheet type specimen is suitable for the in-situ observation. (3) Test condition can be kept constantly and data can be obtained automatically for long test period.

Oral presentation

Internal stresses of pearlitic steel monitored by in-situ neutron diffraction during phase transformation and thermal aging

Morooka, Satoshi; Kawasaki, Takuro; Harjo, S.; Nakada, Nobuo*; Tsukada, Yuki*

no journal, , 

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