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Nishi-Tokyo-shi, Japan

Tanaka T.,Kobe University | Song S.,Kobe University | Hirao T.,Kobe University | Hirose T.,CTI Engineering International Co.
5th China-Japan Geotechnical Symposium | Year: 2013

During excavation of soil from an area with a high groundwater level, seepage failure of soil such as piping or boiling becomes a problem. In recent years, a new type of accident has occurred with respect to seepage failure, because deep excavation has been proceeding due to the construction of large-scale structures. The critical hydraulic head differences between up- and downstream of sheet piles, Hc, that are calculated using standard evaluation methods for seepage failure of soil within a cofferdam, are discussed. In the standards, Hc, is usually calculated conservatively, so a safety factor based on the standard' s formulation, F s, (formula), is defined. In practice, construction work is also conducted under a design safety factor, Fs (design). Thus, the actual or true safety factor, Fs (true), is equal to a product of Fs, (formula) and Fs, (design) : Fs, (true) = Fs, (formula) × Fs (design). In this paper, the evaluation methods by standards are classified into four groups. The actual safety factors for seepage failure of soil are discussed for three flow conditions (2D-, 2DC- and AXS flow). The exact value of Hc is estimated by a Prismatic failure concept presented by the first author, which gives the almost same value of Hc as that obtained by experiments. Source


Fong W.K.,CTI Engineering International Co. | Ho C.S.,University of Technology Malaysia | Lun Y.F.,Tokyo Polytechnic University | Matsumoto H.,Toyohashi University of Technology
HKIE Transactions Hong Kong Institution of Engineers | Year: 2010

For most of the developing countries, socio-economic development is very often the first priority in national development agenda, thus there are very limited actions on climate change mitigation. Malaysia is one of the fast growing developing countries in Asia. Although the Government recognises the importance of energy saving and emission control, there are still very limited policies to address climate change issues and so far no emission reduction target has been set. The main objectives of this study are thus to look into the long-term carbon budget and to examine the necessary energy budgets, based on the case study of the Iskandar Development Region (IDR). Attempts have been made to set the national emission budgets for Malaysia, and from there, city level carbon budgets for IDR were set. Subsequently, simulations using the System Dynamics based computer simulation model were carried out to estimate the necessary energy budgets to achieve carbon budgets for IDR. Source


Nagata K.,Japan International Cooperation Agency JICA | Sayyari M.,Water Resources Management Company | Inaoka M.,Japan International Cooperation Agency JICA | Yajima M.,CTI Engineering International Co.
WIT Transactions on Ecology and the Environment | Year: 2011

Sefidrud River is one of the largest rivers in Iran and its basin extends mainly into seven (7) provinces, where typical water resources conflicts exist between the lower and upper reaches as well as between existing and future water rights. It is of the urgent needs for balanced economic development in the basin to mitigate the conflicts and to realize integrated water resources development and management. This paper reports the progress and result of conflict management among the relevant provinces. Firstly the background of the conflict was clarified and the clues to solutions were analyzed from the viewpoint of water use rights, equity/social justice, economic efficiency and reliability of data and information. Secondly, a collaborative and win-win approach was proposed and applied to the conflict management. Finally some direction toward a conflict solution and realization of the IWRM concept was proposed for the provinces. © 2011 WIT Press. Source


Oneyama H.,Tokyo Metroplitan University | Ozawa S.,CTI Engineering International Co. | Shikata S.,Tokyo Metroplitan University
20th ITS World Congress Tokyo 2013 | Year: 2013

This study examines the effects of the implementation of bus operation information services on bus usage by analyzing the relationships that exist between frequency of bus operation and bus route characteristics, as well as the relationship between external factors, such as bus operation status and the number of bus users. This analysis employs access log data collected from "tobus.jp," the Toei bus operation information service, usage history information drawn from bus IC card data, and bus operation information accumulated in the Toei bus operation management system. Based on the results of comparative analyses of the number of people who accessed the bus system's home page, the number of IC card bus rides, and bus location data, this study examined the relationship between information provided and bus usage. Source


Konagai K.,University of Tokyo | Kiyota T.,University of Tokyo | Suyama S.,University of Tokyo | Asakura T.,CTI Engineering International Co. | And 2 more authors.
Soil Dynamics and Earthquake Engineering | Year: 2013

The March 11th, 2011 Off the Pacific Coast of Tohoku Earthquake, also known as the Great East Japan Earthquake, has shown that a long stretch of landfills along northeastern shorelines of the Tokyo Bay had very high susceptibility to liquefaction, causing concerns about re-liquefactions of the area in the scenario earthquake expected in the capital's metropolitan area. An attempt was made to detect soil subsidence from raster images converted from airborne LiDAR (Light Detection and Ranging) data before and after the earthquake. To eliminate deep-seated tectonic displacements and systematic errors of LiDAR surveys, the template matching technique is used for clusters of pile-supported buildings and bridge piers chosen as templates in source images of the target areas. The obtained subsidence maps describe the spatial distribution of soil subsidence in great detail. © 2013 The Authors. Source

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