Excavation analysis of vertical shaft in sedimentary rock taken into account strain softening and depth variation of rock properties

Sanada, Hiroyuki; Matsui, Hiroya; Ogawa, Toyokazu*; Kinomura, Koji*; Aoki, Tomoyuki*; Yamamoto, Takuya*

JAEA-Research 2009-050, 57 Pages, 2010/01

JAEA-Research-2009-050.pdf:8.14MB

It is important to understand EDZ in assessing performance of repository and designing of plug. It is known that it remains possible that the large-scale EDZ is generated due to strain localization from boring investigations and tunnel excavation analyses and rock properties changes with increase of depth. Excavation analysis of vertical shaft in sedimentary rock taken into account strain softening, depth variation of rock properties and the actual construction procedure had been done in order to understand EDZ of Horonobe URL. The large-scale EDZ due to strain localization was generated around the border between Koetoi formation and Wakkanai formation. From result obtained from excavation analysis, scale of EDZ obtained from excavation analysis is from 60 cm to 120 cm. And it was estimated that seismic velocity changed by 20 percent, elastic modulus changed by 30 percent and hydraulic conductivity changed by 0.1 m/s order.

Evaluation on stability of shaft during excavation, considerating strain softening behavior surrounding rock mass

Kinomura, Koji*; Ogawa, Toyokazu*; Aoki, Tomoyuki*; Yamamoto, Takuya*; Matsui, Hiroya; Sanada, Hiroyuki

Dai-37-Kai Gamban Rikigaku Ni Kansuru Shimpojiumu Koen Rombunshu (CD-ROM), p.307 - 312, 2008/01

no abstracts in English

Monitoring of rock behavior due to shaft excavation using tilt measurements

Nago, Makito*; Ijiri, Yuji*; Kinomura, Koji*; Sato, Masaru*; Shigehiro, Michiko*; Kunimaru, Takanori

no journal, , 

Since a geological disposal repository of nuclear waste will be constructed at depth of a few square kilometers and will be operated for a several tens years, it is crusial to develop a long-term monitoring technology of rock behavior of quite large area. For this purpose, a conventional monitoring method needs a number of deep boreholes and thus needs a huge amount of cost. In this paper, the results of tilt measurements for the shaft excavation at the Horonobe Underground Research Laboratory is presented.

Development of technologies for monitoring rock behaviors using tiltmeter

Ijiri, Yuji*; Nago, Makito*; Kinomura, Koji*; Sugihara, Yutaka*; Shigehiro, Michiko*; Sato, Masaru*; Kunimaru, Takanori

no journal, , 

This paper presents the in-situ measurement data and the results of simulation analyses in order to develop technologies for monitoring rock behaviors using tiltmeters placed near ground surface. From the data, it is shown that the tiltmeters are able to capture the rock behaviors due to shaft excavations and concrete placements and are very sensitive to capture earthquakes, change in barometrical pressure and tide as well as the movements of heavy-construction-equipments. The applicability of inverse analysis for identifying the rock properties using tilting displacement data associated with construction activity is demonstrated by elastic analyses. In addition, the applicability of tiltmeters for monitoring high-permeable zones is also demonstrated by Hydro-Mechanical coupling analysis, because the groundwater flow toward the shaft along high-permeable zone cause an increase in the rate of tilting displacement and change in displacement mode.

Effect of alloying element on defects in electron/neutron-irradiated tungsten

Toyama, Takeshi*; Inoue, Koji*; Nagai, Yasuyoshi*; Kinomura, Atsushi*; Suzudo, Tomoaki; Hatano, Yuji*

no journal, , 

Tungsten (W) is promising as a fusion reactor plasma facing material. Retention and accumulation of hydrogen isotopes become a problem under irradiation, but it was found that the amount of hydrogen isotope accumulation is significantly reduced by the addition of rhenium (Re) and chromium (Cr). This is thought that Re and Cr suppress the formation of vacancy-type defects under irradiation, which are hydrogen trapping sites, but sufficient experimental findings to support this phenomenon have not been obtained yet. The purpose of this study is to apply the positron annihilation method and to investigate the effect of additive elements on the formation of irradiation defects in W alloys under electron beam and neutron irradiation.