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Journal Articles

Mechanical characteristics of rock segment for reducing amount of cement use and stability of drift tunnel

Tada, Hiroyuki*; Kumasaka, Hiroo*; Saito, Akira*; Nakaya, Atsushi*; Ishii, Takashi*; Fujita, Tomo; Sugita, Yutaka; Nakama, Shigeo; Sanada, Masanori*

Doboku Gakkai Rombunshu, F2 (Chika Kukan Kenkyu) (Internet), 73(1), p.11 - 28, 2017/03

This study examined the mechanical characteristics of rock segments and backfill materials and analyzed the stability of the drift that is supported by the rock segments and gravel backfill. The results confirmed the technical aspects of the formation of the rock segments and the effectiveness of the planned efforts to further reduce the amount of cement used.

Journal Articles

Development of rock segment for reduction of amount of cement use

Tada, Hiroyuki*; Kumasaka, Hiroo*; Saito, Akira*; Nakaya, Atsushi*; Ishii, Takashi*; Sanada, Masanori; Noguchi, Akira*; Kishi, Hirokazu*; Nakama, Shigeo; Fujita, Tomo

Dai-13-Kai Iwa No Rikigaku Kokunai Shimpojiumu Koen Rombunshu (CD-ROM), p.133 - 138, 2013/01

The authors have been developing methods for constructing tunnels using the minimum quantities of cement-type support materials in high-level radioactive waste disposal facilities and advancing research and development about the technical formation of rock segment using low alkaline mortar. In this study, the mechanical characteristic values concerning the rock segment and backfill materials were examined. The stability analysis of tunnel supported by the rock segment and backfilling with gravel were performed. Technical formation and effectiveness of the alternative supports planned for further reduction in cement influence was confirmed from a study result above-mentioned.

JAEA Reports

A Study on the technology for reducing cement-type materials used for tunnel supports at high-level radioactive waste disposal sites (Joint research)

Hayashi, Katsuhiko; Noguchi, Akira; Kishi, Hirokazu; Kabayashi, Yasushi*; Nakama, Shigeo; Fujita, Tomo; Naito, Morimasa; Tada, Hiroyuki*; Kumasaka, Hiroo*; Goke, Mitsuo*; et al.

JAEA-Research 2010-057, 101 Pages, 2011/03

JAEA-Research-2010-057.pdf:7.47MB

Cement-type materials that are used for supports or grouting at high-level radioactive waste disposal facilities leach into the groundwater and create a highly alkaline environment. Of concern in highly alkaline environments are the alteration of bentonite used as buffers or backfill materials, and of surrounding rock mass, and the increased uncertainty regarding the provision of performance of the disposal system over a long period of time. In this study, to reduce the quantity of cement-type materials that cause highly alkaline environments, technical feasibility of the support structure including the materials which considered the long-term performance of the HLW disposal system are discussed by using knowledge and technology accumulated in JAEA and Shimizu Construction. Moreover, based on the results, the problems remained in the application to the future HLW disposal institution are summarized.

JAEA Reports

Excavation disturbance analysis based on crack tensor model and virtual fracture model for research drift of the Mizunami Underground Research Laboratory

Goke, Mitsuo*; Horita, Masakuni*; Wakabayashi, Naruki*; Nakaya, Atsushi*

JNC TJ7400 2005-058, 167 Pages, 2005/03

JNC-TJ7400-2005-058.pdf:7.49MB

The purposes of this study were to contribute to both the evaluation of mechanical stability of a research drift and the plan of future studies. The crack tensor model based on mechanical property on the Toki granite at the Mizunami Underground Research Laboratory construction site was applied to analyze the rock stress as a research drift and a shaft were excavated. The virtual fracture model was applied to the hydraulic conductivity change analysis.The results are as follows:1)In the reference case of a shaft, convergence showed 9.03mm at the GL-500m, and 21.78mm at the GL-1000m. The maximum increase rate of hydraulic conductivity showed about 14 times at the both depth. In the reference case of a drift, convergence of a splingline showed 3.36mm at the GL-500m, and 7.99mm at the GL-1000m. The maximum increase rate of hydraulic conductivity showed a range of about 28 times from about 19 times at the GL-500m, and a range of about 45 times from about 15 times at the GL-1000m.2)As rock class getting weaker, the convergence of a shaft and a drift increased, also the stress in support parts increased, while distributions of the safety factor and the hydraulic conductivity change were almost changeless.3)As the direction of a drift changed to 90 degrees form 0 degrees, the convergence of a shaft and a drift increased, also the stress in support parts increased, and distributions of the safety factor and the hydraulic conductivity change were affected.4)As compared with analytical result regardless of excavation damaged zone, analytical result in consideration of excavation damaged zone showed that the convergence and the stress in support parts increased. Especially, the maximum increase rate of hydraulic conductivity increased remarkably. For example, the maximum increase rate of hydraulic conductivity was 240 times to 400 times at the bottom of a drift

Oral presentation

Evaluation of radiation shielding ability of lead glass

Tsuda, Keisuke; Fukushi, Masahiro*; Myojoyama, Atsushi*; Kitamura, Hideaki*; Inoue, Kazumasa*; Nakaya, Giichiro*; Kimura, Junichi*; Sawaguchi, Masato*; Kinase, Sakae; Saito, Kimiaki

no journal, , 

Positron emission tomography (PET) is very effective in the diagnosis and management of patients with various types of cancers. PET scanning with the tracer FDG is widely used in clinical PET. However, the effective dose constant of the positron emitter is about eight times of nuclide $$^{99m}$$Tc used in a nuclear medicine diagnosis widely. Severe radiation protection is necessary for development of the examination with a positron emitter. Radiation protection in the PET institution therefore and safe security are problems. Hence, lead glass has attracted considerable attention as the radiation shielding materials of the PET institution. In the present study, we received a request of the radiation shielding ability evaluation of two kinds of lead glass made in Pilkington plc. The aim of the present work is the radiation shielding ability evaluation for positron emitter such as $$^{18}$$F(511 keV) of the lead glass. The shielding ability evaluation has been studied in the experimental and the Monte Carlo simulation evaluation. Consequently, effective dose transmission factor with experimental and the Monte Carlo simulation value was calculated. There were enough protection effects to evaluated lead glass. Furthermore, radiation shielding ability evaluation for $$^{137}$$Cs(662 keV), $$^{60}$$Co(1.17, 1.33 MeV) was performed, and it was shown that there was a similar protection effect.

Oral presentation

Development of construction method for a drift minimizing use of cementious material, 7; Experimental study on the rock mortar composite material based on low alkaline cement

Saito, Akira*; Nakaya, Atsushi*; Tada, Hiroyuki*; Kumasaka, Hiroo*; Kobayashi, Yasushi

no journal, , 

no abstracts in English

Oral presentation

Development of construction methods of a drift to be reduction of amount of cement use, 8; The Bending test of the rock segment using low alkaline mortar

Saito, Akira*; Goke, Mitsuo*; Nakaya, Atsushi*; Tada, Hiroyuki*; Hayashi, Katsuhiko; Noguchi, Akira; Kishi, Hirokazu; Nakama, Shigeo

no journal, , 

We are supposing a low cement use tunner support made for granite rock block connecting low alkaline cement applying to HLW repositories. Because of the bending moment of the segment by dead load and the variance of the earth pressure, We made a model segment bending experiment to get a mechanical properties. The maximum load of the positive bending moment is around 210kN, which is around twice of the dead load of 117kN. The other hand, the maximum load in the negative bending moment is around 44kN, as same as the dead load. As the result of observating the cracks of the model segment, We found three or four cracks along the surface of the boundary of the rock block and mortar in the positive bending experiment. The other hand, we found only one crack at the center avoiding rock block in the negative bending experiment. Next, we will improve the construction method, prevention of the crack in the segment and the exfoliation of mortar and the steel panel.

Oral presentation

Development of construction methods of a drift to be reduction of amount of cement use, 9; Test of a deformation of macadam and stability of drift tunnel

Kumasaka, Hiroo*; Saito, Akira*; Nakaya, Atsushi*; Tada, Hiroyuki*; Hayashi, Katsuhiko; Noguchi, Akira; Kishi, Hirokazu; Nakama, Shigeo

no journal, , 

We are proposing to use the rock segment reducing the amount of the cementutious materials. In this report, we are getting young's modulus and poisson's ratio from the deformation experiment of the macadam mass, and performed a stability analysis of the gallery filled with macadam between the hostrock and the rock segment. We performed a alternating bearing test with high confirming pressure, and we estimated the Young's modulus and the poisson's ratio of the mass macadam from the result of the bearing test. After that, we performed the stability analysis of the galleries in the condition of the JAEA second report with the rock segment and the macadam. We found that the strain at the surface of the host rock is smaller than that of conventional one, and the stability of the host rock is remained, and the compressive stress in the rock segment is the half of the compressive strength of it. We considered that the rock segment support system is stable enough for the supporting system.

Oral presentation

Development of construction methods of a drift to be reduction of amount of cement use, 10; Study on bending properties of the rock segment using low alkaline mortar

Tada, Hiroyuki*; Saito, Akira*; Nakaya, Atsushi*; Kumasaka, Hiroo*; Hayashi, Katsuhiko; Noguchi, Akira; Kishi, Hirokazu; Nakama, Shigeo

no journal, , 

Bending test of the segmental rings consist of staggered pieces of rocks bonded by low-pH mortar is conducted in order to identify the mechanical properties of rock segmental rings comparing with parallel arrangement. As a result, it was found that the maximum load was reached at 130 to 210 kN in the positive bending tests for staggered rock blocks, lower than 210 to 270 kN for rock blocks arranged in parallel. In the negative bending tests, on the other hand, the maximum load was reached at 30 to 40 kN, lower than a maximum load of 40 kN for the rock blocks arranged in parallel. The results thus varied. Cracks occurred along the interface between the rock block and mortar in the specimen for the blocks arranged in parallel. For the staggered rock blocks, cracks penetrated through the mortar and the rock block near the point of loading in the specimen. Thus, it was confirmed that cracking occurred in different manners.

Oral presentation

In-tunnel spraying test of low-alkali quick setting shotcrete, 3; Shotcreting test, support performance verification test

Nakaya, Atsushi*; Tada, Hiroyuki*; Okuyama, Yasuji*; Iwasaki, Masahiro*; Kusano, Takashi*; Kubo, Yohei*; Yamawaki, Hiroyuki; Sato, Toshinori

no journal, , 

no abstracts in English

10 (Records 1-10 displayed on this page)
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