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Kunimatsu S.,Japan National Institute of Advanced Industrial Science and Technology | Hirao Y.,Kobayashi Institute of Physical Research | Kitamura Y.,Construction Engineering Research Institute Foundation
Journal of Modern Transportation | Year: 2012

Ground-borne vibrations caused by vibration sources such as road traffic and construction exhibit complicated properties during propagation from the vibration source to the inside of a building. In the present paper, a numerical analysis technique for the system of vibration source and propagation path of ground vibration is developed in order to systematically determine the propagation properties of the vibration as part of developing a predictive technique for exposure evaluations by vibrations in three directions at receiving points of vibration in the human body. First, the exciting forces in three directions for input into the numerical computation are inversely-estimated by using the measured acceleration records of the measurement points, which are near the vibration source. The thin-layered element method is used for numerical computation of the ground vibration. Then, the calculation results for the ground vibration obtained by using the estimated exciting force are compared with the measured results, and the influence of the stratified structure of the ground on the exciting force and the propagation properties of the ground vibration are studied. From these results, in a prediction of the ground vibration in three directions, it is emphasized that it is necessary to consider the influence of horizontal exciting force, although attention has been paid to only the vertical exciting force for simulating ground vibration. © 2012 JMT. All rights reserved. Source

Otsuka I.,Taisei Corporation | Taki H.,Taisei Corporation | Aoki T.,Taisei Corporation | Shimo M.,Taisei Corporation | And 3 more authors.
Harmonising Rock Engineering and the Environment - Proceedings of the 12th ISRM International Congress on Rock Mechanics | Year: 2012

This project is named 'Marmaray' which is a coined word combining the sea of Marmara and railway. The Marmaray Project is the upgrading of approximately 76 kilometers of commuter rail to improve the railway system in Istanbul metropolitan area. Railway tracks will be connected between Asia and Europe through a tunnel under the Bosphorus Strait. Tunnels and stations have been and will be constructed by some methods such as immersed tunnel, shield tunnel, mountain tunnel, and cut and cover in 13.6 km length of this project. In this report, it is described that the observational construction management by field measurement is performed in large scale underground railway station (Sirkeci station) by means of NATM. © 2012 Taylor & Francis Group, London. Source

Mori T.,Tohoku University | Tobita Y.,Tohoku Gakuin University | Okimura T.,Construction Engineering Research Institute Foundation
Soils and Foundations | Year: 2012

The 2011 off the Pacific Coast of Tohoku Earthquake resulted in severe damage to housing and housing lots. In particular, the hillside embankments for residential use surrounding the downtown of Sendai city suffered serious damage. Many hillside lands which had been damaged during the 1978 off Miyagi-Prefecture earthquake were subjected to further damage. Typical damaged hillside embankments in Sendai city were investigated and the causes of the damage were discussed in this paper. The main cause of the damage to housing was not the seismic motion but the ground displacement of the fill embankment. A comparison of the damage from the 2011 earthquake with that from the 1978 earthquake indicates that the countermeasures constructed after the 1978 earthquake performed well in that they prevented large landslide type failure; however, they were not successful in reducing the amount of damage to housing or housing lots due to ground displacements from cracks, differential settlement, and shallow slips. A classification of failure types of fill embankment is proposed to be of assistance in the choice of countermeasures. © 2012 The Japanese Geotechnical Society. Production and hosting by Elsevier B.V. All rights reserved. Source

Okimura T.,Construction Engineering Research Institute Foundation | Torii N.,Kobe University | Osaki Y.,Hyogo Prefectural Government | Nanbu M.,Oyo Corporation | Haraguchi K.,Kokusai Kogyo Co.
Geotechnical Engineering | Year: 2010

Japan has been vulnerable to landslide disasters caused by heavy rainfalls. The most common trigger of landslide disasters in our country is slope failure. In order to mitigate landslide disasters, it is important to evaluate the potential of slope failure events in space and time quantitatively and to develop the system that send the disaster information based on result of the evaluation. We have developed the system of real-time type hazard map of slope failure disasters caused by heavy rainfalls. In this paper, we focus on the depth of surface soil layer, which is one of the input parameters, and aim at a further improvement of prediction accuracy of the slope failure potential. Source

Sakurai S.,Construction Engineering Research Institute Foundation
Acta Geotechnica | Year: 2010

This paper deals with the modeling of jointed rock masses reinforced by rock bolts. It is well known that rock bolts are extremely effective in reinforcing jointed rocks. However, if a continuum approach is adopted for modeling jointed rock masses, it is often misleading to evaluate the effectiveness of the rock bolts by numerical analyses such as the finite element method. This may be due to the fact that since no more joints exist in the continuum, the effectiveness of the rock bolts in constraining the relative displacements along the joints cannot be evaluated properly. In order to investigate the reinforcement effect of rock bolts, physical model tests were performed in the laboratory. The test results revealed that jointed rock masses should be modeled as an equivalent continuum after the installation of rock bolts and that the mechanical parameters of the equivalent continuum should be evaluated by considering the reinforcement effect of the rock bolts. Therefore, the values of the mechanical parameters differ from place to place in accordance with the relation between joint orientation and rock bolt direction, even though joint systems are homogeneous. In conclusion, in the continuum approach for modeling jointed rock masses, it should be emphasized that rock bolts and jointed rock masses should not be modeled separately but should be modeled simultaneously by considering the reinforcement effect of the rock bolts in constraining joint movement. The modeling of shotcrete reinforced by steel ribs is also discussed in comparison to the modeling by rock bolts. © 2010 Springer-Verlag. Source

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