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Cao Y.,Tongji University | Peng F.,Tongji University | Kotake N.,Toyo Construction Co. | Tatsuoka F.,Tokyo University of Science
Yanshilixue Yu Gongcheng Xuebao/Chinese Journal of Rock Mechanics and Engineering | Year: 2010

The results from the laboratory model test on reinforced sand slope were simulated numerically by the nonlinear elastoplastic finite element method(FEM) considering the strain localization; and they were compared with the results from the unreinforced sand slope. Then, the elastoplastic finite element analysis of a reinforced sand slope with facing plates was also performed numerically to understand the effect of facing by adding the facing plates into the finite element model for reinforced sand slope. In the finite element analysis, strain localization(or shear banding), strain-hardening, strain-softening, strength anisotropy and pressure dependency were considered for sandy soil. It was found that the presented finite element analysis could properly simulate the local stress-strain distribution and development of shear bands within the slopes, which could better understand the progressive failure characteristics of reinforced sand slopes, reinforcing mechanism of strips and the facing effect. Source


Peng F.,Tongji University | Cao Y.,Tongji University | Kotake N.,Toyo Construction Co. | Siddiquee M.S.A.,Bangladesh University
Yanshilixue Yu Gongcheng Xuebao/Chinese Journal of Rock Mechanics and Engineering | Year: 2010

The plane strain compression tests of dense sand reinforced with a smooth brass plate are simulated numerically with a finite element method(FEM). Considering the slippage at the interface between the sand and the reinforcement, Goodman joint elements are used as interface elements in the numerical simulation. In the finite element analysis, the effects of the following factors for sand are also taken into account:(1) correlation of confining pressure; (2) anisotropy of strength; (3) nonlinear characteristics of pre-peak strain-hardening and post-peak strain-softening; (4) dilatancy; and (5) strain localization and forming characteristics of shear zone. The results indicate that the strain-stress relationship obtained by the proposed finite element analysis is generally in good agreement with that of plane strain compression tests. It is found that the maximum stress ratio and pre-peak stiffness in the finite element analysis are quite close to the results of tests. In addition, the results also indicate that the progressive failure of reinforced sand with a development of shear zone can be reasonably examined by the proposed finite element analysis, and the interaction between sand reinforcement at the interface can be well understood. Source


Ito D.,Yokohama National University | Akira Y.,Port and Airport Research Institute | Akira Y.,Toyo Construction Co. | Miyata Y.,Yokohama National University | And 2 more authors.
ECS Transactions | Year: 2012

A high performance organic coating is used for the corrosion protection of large steel constructions. Since the degradation of the coating takes long time, the degradation evaluation is difficult. Previously, the degradation of a coating was evaluated by electrochemical impedance method. However, these subjects of research were a coating with thin film thickness. Therefore, the evaluation of the high performance or the thick thickness coating is insufficient. The authors reported on the evaluating of the growth of the blistering of the coating. In this research, the degradation of the coating before blisters occur was evaluated as the penetration by water and chloride ion. The acceleration of coating degradation could be used as an outdoor salt spray test. © The Electrochemical Society. Source


Enomoto T.,Toyo Construction Co.
Proceedings WODCON XX - Congress and Exhibition: The Art of Dredging | Year: 2013

Radioactive materials released into the atmosphere following the accident at the Fukushima Daiichi Nuclear Power Plant fell across a wide region of Japan. A significant portion of this radioactive fallout was adsorbed into soil particles and carried into streams and rivers, eventually accumulated on the bottoms of lakes, reservoirs, and other bodies of water. Little is known at this point regarding the distribution and characteristics of the radioactive materials and the soil particles to which they were adsorbed. Our research seeks to identify and develop technologies for decontaminating such benthic sediment and reducing the volumes of contaminated soil. As part of these efforts, rather than drawing on new and special mechanisms, we explored ways to achieve the decontamination desired by modifying and combining existing dredging and dehydration technologies. This study focuses on the following aspects of soil decontamination and soil volume reduction technologies: (1) Understanding the distribution of radioactive contaminants (2) Soil decontamination technologies (3) Soil volume reduction technologies. © 2013 WODA. Source


Kobayashi H.,Port and Airport Research Institute | Yamaji T.,Port and Airport Research Institute | Akira Y.,Toyo Construction Co. | Hamada H.,Kyushu University | And 2 more authors.
Zairyo to Kankyo/ Corrosion Engineering | Year: 2013

We investigated retrofit design in cathodic protection (CP) with galvanic anodes made from an aluminum alloy. In conventional retrofit design, the decrease in CP current reduction (which affects the life of anodes) is estimated based on nominal durability values. The current reduction rate falls to a level far below the design value, leading to an increased number of facilities in which the anode life exceeds the design service life. As this trend is due to exaggerated design, it is necessary to review retrofitting methods in order to enable more effective and economical maintenance. After detailed analysis and discussion, we developed an innovative methodology for an optimized maintenance system in galvanic anode CP. To test the assumptions made, we conducted on-site, shortterm testing with an actual structure and confirmed the validity of the new design methodology. The method, which takes current reduction into consideration, allowed more accurate prediction of anode life and a reduction in the initial costs of CP facilities. Source

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