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Koda M.,Foundation and Geotechnical Engineering Laboratory
Quarterly Report of RTRI (Railway Technical Research Institute) (Japan)

A Committee for Design Standards for Railway Structures & Commentaries [Foundation and Retaining Structures] (Chairman Prof Osamu KUSAKABE, Tokyo Institute of Technology, Vice-chairman Prof. Junichi KOSEKI, Tokyo University) was established in 2005 to draft a revised version of "Design Standards for Railway Structures & Commentaries [Foundation and Retaining Structures]"presented at the last committee meeting in July 2008. The revised sections were "an introduction to performance based design"; "design model revision taking into account the subgrade reaction modulus" and "an introduction to new foundation materials and foundation construction methods". This paper discusses the recent trends in railway foundation design technology, and highlights from the contents of the revised version. Source

Koda M.,Laboratory Head | Tateyama M.,Laboratory Head | Yokoyama T.,JR Central Consultants Company | Nonaka T.,Foundation and Geotechnical Engineering Laboratory | Kobayashi Y.,Steel and Composite Structures Laboratory
Quarterly Report of RTRI (Railway Technical Research Institute)

Japan's railways began operations about 140 years ago. The majority of its steel railway bridges now have 50 years or more of service. It is therefore expected that the number of steel bridges requiring repair, reinforcement or replacement will increase in the future. Consequently, the Railway Technical Research Institute is proposing a method to extend the life and strengthen the earthquake resistance of deteriorated steel-girder and abutment-type bridges without replacing steel girders, by integrating the following structures: (1) Abutments and backfills with reinforced concrete (RC) walls that are connected to each other rigidly with nail-reinforced soil; (2) Connecting steel girders and abutments with reinforced concrete; These are measures which improve the function of steel girders, abutments and backfills in normal service periods and during earthquakes. Bridges reinforced with this type of structure are called "Integral Bridges with Nail-Reinforced Soil (NRS-Integral Bridges).". Source

Shinoda M.,Foundation and Geotechnical Engineering Laboratory
Quarterly Report of RTRI (Railway Technical Research Institute)

Cyclic load by train causes subsidence of railway level in tunnels, which is due to ground deformation under roadbed concrete. In consideration of progress of track irregularities and core drilling results, the deformation of the roadbed concrete have been evaluated, but there has been no quantitative inspection method until the present. In this study, to develop a method for quantitative evaluation of train running stability on the slab placed on roadbed concrete, a method to survey roadbed concrete by vibrating it with small-sized and medium-sized vibration exciter was proposed. Vibration characteristic of roadbed concrete with accel-erometers fixed near the vibration position was also evaluated. Then the correlation between progress of track irregularities considered to be correlated with the soundness of roadbed concrete and the results of vibration tests was confirmed, and a method for evaluation of the correlation was proposed. Source

Matsumaru T.,Foundation and Geotechnical Engineering Laboratory | Kojima K.,Foundation and Geotechnical Engineering Laboratory | Tanaka Y.,JR East Consultants Company | Kuriyama R.,Fukken Engineering Co.
Quarterly Report of RTRI (Railway Technical Research Institute)

Monitoring of the deformation of earth retaining walls for excavating work is vital in order to protect the surrounding environment and to ensure the safety of structures during construction. Since it is difficult to evaluate the overall behavior with only partial measurement, it is expedient to introduce multipoint measurement. However, this method tends to be expensive. This paper introduces a system developed for evaluating and visualizing retaining walls as a three-dimensional curved surface. In order to confirm the effectiveness of the proposed system in actual monitoring, the system was applied to the on-site measurement. This paper also proposes a method of monitoring retaining walls by combining this system and simple inclinometers. Source

Nishioka H.,Foundation and Geotechnical Engineering Laboratory | Shinoda M.,Foundation and Geotechnical Engineering Laboratory | Koda M.,Foundation and Geotechnical Engineering Laboratory | Tateyama M.,Structures Technology Division
Quarterly Report of RTRI (Railway Technical Research Institute) (Japan)

The design bearing capacity of piles can be calculated by multiplying the characteristic value with its corresponding resistance factor. In this study, we proposed a method for calculating these parameters from a loading test database of several different construction methods. Initially, we proposed the formula for calculating the characteristic value by using results from a ground investigation. Secondly, we proposed the resistance factor obtained from the statistical analysis of the loading test database by use of the first-order reliability method. The proposed method can be used to compare the effectiveness of various pile construction methods with the same reliability. Source

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