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Journal Articles

A Study on support design for deep shaft sinking in rock masses of low strength and anisotropic initial stress

Motoshima, Takayuki*; Koike, Masashi*; Hagihara, Takeshi*; Aoyagi, Kazuhei

Dai-46-Kai Gamban Rikigaku Ni Kansuru Shimpojiumu Koenshu (CD-ROM), p.208 - 213, 2019/01

The short step construction method is the standard construction method for deep shaft excavation. However, considering the shaft construction in the sedimentary rock widely distributed in Japan, the support concrete stress can become excessive especially when there are bad conditions such as low rock strength, anisotropic initial stress, or high ground pressure. In this research, we introduced the dual support design to the short step construction method in order to reduce the support stress, and confirmed the validity by three dimensional numerical analysis. Validation analysis was conducted using the in-situ data in the Horonobe Underground Research Project conducted by Japan Atomic Energy Agency.

JAEA Reports

Annual report on the environmental radiation monitoring around the Tokai Reprocessing Plant FY2016

Nakano, Masanao; Fujita, Hiroki; Mizutani, Tomoko; Nemoto, Masashi; Tobita, Keiji; Hosomi, Kenji; Nagaoka, Mika; Hokama, Tomonori; Nishimura, Tomohiro; Koike, Yuko; et al.

JAEA-Review 2017-028, 177 Pages, 2018/01

JAEA-Review-2017-028.pdf:3.61MB

Environmental radiation monitoring around the Tokai Reprocessing Plant has been performed by the Nuclear Fuel Cycle Engineering Laboratories, based on "Safety Regulations for the Reprocessing Plant of Japan Atomic Energy Agency, Chapter IV - Environmental Monitoring". This annual report presents the results of the environmental monitoring and the dose estimation to the hypothetical inhabitant due to the radioactivity discharged from the plant to the atmosphere and the sea during April 2016 to March 2017. In this report, some data include the influence of the accidental release from the Fukushima Daiichi Nuclear Power Station of Electric Power Company Holdings, Inc. in March 2011. Appendices present comprehensive information, such as monitoring programs, monitoring methods, monitoring results and their trends, meteorological data and discharged radioactive wastes. In addition, the data which were influenced by the accidental release and were exceeded the normal range of fluctuation in the monitoring, were evaluated.

Journal Articles

Influence of rock spalling on concrete lining in shaft sinking at the Horonobe Underground Research Laboratory

Tsusaka, Kimikazu; Inagaki, Daisuke; Nago, Makito*; Koike, Masashi*; Matsubara, Makoto*; Sugawara, Kentaro*

Dai-13-Kai Iwa No Rikigaku Kokunai Shimpojiumu Koen Rombunshu (CD-ROM), p.911 - 916, 2013/01

A repository for high-level radioactive waste in deep underground consists of several underground structures such as access and disposal drifts and shafts. In deep geological disposal project, a shaft is the first underground structure to be constructed and the last one to be backfilled. Therefore, the stability of shaft is one of key factors to steadily manage the project in the construction and operation phases. In this paper, the authors discuss influence of rock spalling on concrete lining in shaft sinking. Japan Atomic Energy Agency has been constructing three shafts (one is for ventilation and the others are for access use) up to a depth of 500 m in the Horonobe Underground Research Laboratory. During the construction of the Ventilation Shaft (4.5 m in diameter) below a depth of 250 m, rock spalling occurred at several depths and an open crack has developed in a concrete lining installed just above rock spalling. The authors have measured geometry of shaft wall by using three-dimensional laser scanner. They also conducted numerical analysis in order to calculate change in stress distribution and deformation induced by rock spalling in a concrete lining and the surrounding rock. As a result, it was clarified that rock spalling induced tensile stress in the vertical direction in a concrete lining. Especially, the tensile stress in a concrete lining was likely to exceed tensile strength of a concrete lining in the case that it developed more than 100 cm in depth.

Journal Articles

A Study on rock mass behaviour induced by shaft sinking in the Horonobe Underground Research Laboratory

Tsusaka, Kimikazu; Tokiwa, Tetsuya; Inagaki, Daisuke; Hatsuyama, Yoshihiro*; Koike, Masashi*; Ijiri, Yuji*

Doboku Gakkai Rombunshu, F1 (Tonneru Kogaku) (Internet), 68(2), p.40 - 54, 2012/09

Japan Atomic Energy Agency has excavating three deep shafts through soft sedimentary rock at Horonobe Underground Research Laboratory. In this paper, the author discussed rock mass behaviour induced by the 6.5 m diameter shaft sinking. They conducted geological mapping in an excavation face and boreholes digged around the shaft wall, field measurements such as convergence measurements and monitoring of rock displacements using multi-interval borehole extensometers around a shaft at around 160 m and 220 m in depths, and three-dimensional numerical analysis which models the shaft excavation procedure such as timing of installation of support elements and setting and removal of a concrete form. As a result, it was clarified that remarkablely large compressive strains occurred within about 1 m into the shaft wall since the rock mass behaviour was controlled by the concrete lining and that the behaviour would predominantly be induced by the fractures closing which opened significantly and propagated during excavation steps before the installation of a concrete lining and the directions where the strains occurred heavily depended on the fracture orientation around the shaft.

Journal Articles

A Study on mechanical behaviour of support elements induced by shaft sinking

Tsusaka, Kimikazu; Inagaki, Daisuke; Hatsuyama, Yoshihiro*; Koike, Masashi*; Shimada, Tomohiro*; Ijiri, Yuji*

Doboku Gakkai Rombunshu, F1 (Tonneru Kogaku) (Internet), 68(1), p.7 - 20, 2012/05

Japan Atomic Energy Agency has excavating three deep shafts through soft sedimentary rock at Horonobe Underground Research Laboratory. In this paper, the author discussed change in stress and the stress distribution in a concrete lining and steel arch sets induced by the 6.5 m diameter shaft sinking. They conducted not only field measurements of stress in support elements at around 220 m in depth but also three-dimensional numerical analysis which models the shaft excavation procedure such as timing of installation of support elements and setting and removal of a concrete form. As a result, it was clarified that more than 10 MPa difference in circumferential stress occurred in a 2 m high and 400 mm thick concrete lining due to anisotropy of initial stress and three-dimensional effect of an excavation face. It was also found that a concrete lining gradually deformed from an original cylindrical form to an "oval salad bowl" form with the long axis pallarel to the direction of the minimum horizontal principal stress after a concrete form was removed.

Journal Articles

A Study on mechanical behaviors of concrete lining and rock caused by shaft sinking at the Horonobe Underground Research Laboratory

Tsusaka, Kimikazu; Inagaki, Daisuke; Koike, Masashi*; Ijiri, Yuji*; Hatsuyama, Yoshihiro*

Harmonising Rock Engineering and the Environment, p.305 - 308, 2011/10

In this paper, the authors discussed circumferential stress distribution in a concrete lining and displacement of rock around shaft wall induced by shaft excavation at Horonobe Underground Research Laboratory. Field measurements of the lining stress and rock displacement were conducted between 218 m and 220 m in depths during excavation of a 6.5 m diameter access shaft and the results were analyzed using a three-dimensional numerical model. As a result, it was found that the maximum and minimum stresses occurred in the direction of horizontal minimum and maximum initial stresses, respectively. It was also clarified that difference in the stress between the maximum and minimum values was beyond 10 MPa. In addition, it was found that compressive axial strain occurred around a shaft wall after casting concrete lining since rock behavior in the vicinity of shaft wall was controlled by a concrete lining.

Journal Articles

Study on the behavior of concrete lining and rock mass during shaft excavation in the Horonobe URL Project, 1

Inagaki, Daisuke; Tsusaka, Kimikazu; Ijiri, Yuji*; Koike, Masashi*; Hatsuyama, Yoshihiro*

Dai-40-Kai Gamban Rikigaku Ni Kansuru Shimpojiumu Koen Rombunshu (CD-ROM), 6 Pages, 2011/01

no abstracts in English

Journal Articles

A Study on the behaviour of concrete lining and rock mass during shaft excavation at the Horonobe URL project, 2

Tsusaka, Kimikazu; Inagaki, Daisuke; Koike, Masashi*; Ijiri, Yuji*; Hatsuyama, Yoshihiro*

Dai-40-Kai Gamban Rikigaku Ni Kansuru Shimpojiumu Koen Rombunshu (CD-ROM), p.7 - 12, 2011/01

no abstracts in English

Oral presentation

Study on the behavior of concrete lining and rock mass during shaft excavation by means of short step method

Sakai, Kazuo*; Koike, Masashi*; Aoki, Tomoyuki*; Yamamoto, Takuya*; Hatsuyama, Yoshihiro*; Yamazaki, Masanao

no journal, , 

In a construction project of the Horonobe URL, vertical shafts are excavated now by the Short Step method. This paper examines the behavior of concrete lining and rock mass around the shaft. To reflect the excavation sequence, a 3-D analysis is performed, modeling rock mass and support members around an advancing face. The analysis shows well specific phenomena of the Short Step method, as in the rock mass displacement and lining stress. It also reveals lining stress distribution are complex. In future, it is important to investigate lining stress through detailed measurements.

Oral presentation

A Study on the support stress during shaft excavation using the short step method

Koike, Masashi*; Ijiri, Yuji*; Inagaki, Daisuke; Tsusaka, Kimikazu

no journal, , 

no abstracts in English

Oral presentation

A Study of the segment length of the concrete shaft lining using the short step method

Hagihara, Takeshi*; Koike, Masashi*; Sekiya, Yoshitomo*; Itabashi, Hideharu; Ohara, Masatsugu

no journal, , 

no abstracts in English

Oral presentation

Development of construction technologies for underground facility; Attempt at the Horonobe Underground Research Laboratory Project

Inagaki, Daisuke; Tsusaka, Kimikazu; Miura, Yoichi*; Nago, Makito*; Shindo, Akihisa*; Ijiri, Yuji*; Koike, Masashi*; Hatakenaka, Chino*

no journal, , 

no abstracts in English

12 (Records 1-12 displayed on this page)
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