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Yamazaki, Masanao; Sekiya, Yoshitomo; Fujikawa, Daisuke; Kitagawa, Yoshito*
Chika Kukan Shimpojiumu, Rombunshu, 14, p.191 - 196, 2009/01
The shafts and drifts of the Horonobe Underground Research Laboratory Project have been constructed by JAEA. The construction method of shaft is a short step method. The East Shaft of excavation system is the blasting excavation, and the Ventilation Shaft is the machine excavation. At the present, The East Shaft has ended to G.L.-140.5 m and Ventilation Shaft has ended to G.L.-210.5 m at the end of July, 2008. The difference in depth change or a excavation system was analyzed about the excavation time which occupies about 40% of the cycle time of each shaft. This paper reports the outline of the construction track record of the shafts and the result of having analyzed cycle time paying attention to excavation time.
Yamanishi, Takeshi; Sekiya, Yoshitomo; Suzuki, Tatsuya; Ito, Seiji; Kitagawa, Yoshito*; Hagihara, Takeshi*; Doi, Takashi*; Saito, Ryosuke*
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Kitagawa, Yoshito*; Yamazaki, Masanao; Hagihara, Takeshi*; Minamide, Masashi*; Sekiya, Yoshitomo
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Yamanishi, Takeshi; Sekiya, Yoshitomo; Suzuki, Tatsuya; Kitagawa, Yoshito*; Saito, Ryosuke*; Yokota, Daisuke*
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Sano, Michiaki; Sekiya, Yoshitomo
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Yamanishi, Takeshi; Sekiya, Yoshitomo; Inagaki, Daisuke; Hatsuyama, Yoshihiro*; Kitagawa, Yoshito*
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Kitagawa, Yoshito*; Minamide, Masashi*; Nayuki, Toshinori*; Yamanishi, Takeshi; Sekiya, Yoshitomo; Ito, Seiji; Sato, Haruo; Nakayama, Masashi
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In Japan, any high level radioactive waste repository is to be constructed at over 300m depth below surface. Tunnel support is used for safety during the construction and operation, and shotcrete and concrete lining are used as the tunnel support. Concrete is a composite material comprised of aggregate, cement and various additives. Low alkaline cement has been developed for the long term stability of the barrier systems whose performance could be negatively affected by highly alkaline conditions arising due to cement used in a repository. Japan Atomic Energy Agency (JAEA) has developed a low alkaline cement, named as HFSC (High fly-ash silicafume cement), containing over 60wt% of silica-fume (SF) and coal ash (FA). JAEA are presently constructing an underground research laboratory (URL) at Horonobe for research and development in the geosciences and repository engineering technology. HFSC was used experimentally as the shotcrete material in construction of part of the 140m deep gallery in Horonobe URL. The objective of this experiment was to assess the performance of HFSC shotcrete in terms of mechanics, workability, durability, and so on. HFSC used in this experiment is composed of 40wt% OPC (Ordinary Portland Cement), 20wt% SF, and 40wt% FA. This composition was determined based on mechanical testing of various mixes of the above components. Because of the low OPC content, the strength of HFSC tends to be lower than that of OPC in normal concrete. The total length of tunnel using HFSC shotcrete is about 73m and about 500m of HFSC was used. This experimental construction confirmed the workability of HFSC shotcrete. Although several in-situ experiments using low alkaline cement as shotcrete have been performed at a small scale, this application of HFSC at the Horonobe URL is the first full scale application of low alkaline cement in the construction of a URL in the world.
Yamanishi, Takeshi; Sekiya, Yoshitomo; Sataka, Hiroyuki; Kitagawa, Yoshito*; Kato, Kinya*
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Yamanishi, Takeshi; Sekiya, Yoshitomo; Suzuki, Tatsuya; Kitagawa, Yoshito*; Kato, Kinya*; Saito, Ryosuke*
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Sekiya, Yoshitomo; Shimoyama, Tadashi; Anada, Hideki*; Kanatani, Tsugio*; Yamanishi, Takeshi
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Sekiya, Yoshitomo; Shimoyama, Tadashi; Hirakawa, Yoshiaki*; Narashima, Yoshimasa*; Yamanishi, Takeshi
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Sekiya, Yoshitomo; Kitagawa, Yoshito*; Igarashi, Toshifumi*; Hokora, Hideyuki*
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Sekiya, Yoshitomo; Kitagawa, Yoshito*; Igarashi, Toshifumi*; Hokora, Hideyuki*
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Sekiya, Yoshitomo; Kitagawa, Yoshito*; Igarashi, Toshifumi*; Hokora, Hideyuki*
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Itabashi, Hideharu; Sekiya, Yoshitomo*; Sataka, Hiroyuki; Shimada, Tomohiro*; Kato, Kinya*
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Hagihara, Takeshi*; Koike, Masashi*; Sekiya, Yoshitomo*; Itabashi, Hideharu; Ohara, Masatsugu
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