• Search Research Projects
  • Search Researchers
  • How to Use
  1. Back to project page

2002 Fiscal Year Final Research Report Summary

Seismic deformation of composite breakwaters and embankments on saturated sandy ground with reference to torsional cyclic behavior of sand after phase transformation

Research Project

Project/Area Number 13650548
Research Category

Grant-in-Aid for Scientific Research (C)

Allocation TypeSingle-year Grants
Section一般
Research Field Geotechnical engineering
Research InstitutionTOKAI UNIVERSITY

Principal Investigator

KITA Katsutoshi  Tokai University, Faculty of Marine Science and Technology, Associate Professor, 海洋学部, 助教授 (60234225)

Project Period (FY) 2001 – 2002
Keywordsearthquake / breakwater / embankment / settlement / saturated sand / cyclic plasticity / phase transformation / pore pressure
Research Abstract

In the 1995 Hyogoken-Nambu earthquake, some composite breakwaters in Kobe port experienced over 2.5m settlement due to strong ground shaking. In this study, a series of shaking table tests were conducted on breakwater- and embankment-foundation saturated sandy ground system is centrifugal conditions of 30-g and 50-g with viscous scaling incorporated, in order to clarify the mechanism of such large settlements. The deformation characteristics of the foundation ground were then discussed referring to the results of undrained cyclic torsional shear tests on anisotropically consolidated loose sand. Results obtained from these experiments are summarized as follows:
(1) In centrifuge model tests, foundation ground just beneath the main part of a composite breakwater may undergo large axial deformation (vertical compression associated with horizontal extension) during ground shaking, due to the undrained cumulative shear deformation mechanism, which becomes operational once effective stresses … More reach phase transformation states. The vertical compressive strains in the middle and/or lower (deep) layers were larger than those in the shallow layers.
(2) Vertical and torsional shear strains developed significantly after the stress paths reached the transformation lines in cyclic torsional shear tests. The vertical strains cumulated, however the strain increments decreased with the number of cyclic shearing. Larger the initial consolidation stress ratio K=σ'_<z0>/σ'<I0*> (σ'_z0> and σ'_<r0> are respectively the initial vertical and horizontal effective stresses), the effective confining stress at phase transformation is larger, leading smaller cumulative vertical strain of sand specimen. According to linear elastic finite element analysis on stresses induced by the self-weight of composite breakwater-foundation ground system, large shear stresses were introduced prior to shaking at the shallow part of the foundation ground. The profiles of vertical compression observed in centrifuge experiments can be explained with the elemental performance.
The above-mentioned results indicate the significance of soil behavior after phase transformation, which may have been incorporated to less extent in current analytical schemes. In such analyses, for example, the constitutive parameters may often be determined based on the cyclic shear stress ratio - number of shear repetition relationship governed by pre-phase transformation process. Less

  • Research Products

    (6 results)

All Other

All Publications (6 results)

  • [Publications] Kita, K., Yamada, H.: "Centrifuge modeling of seismic settlement of composite breakwaters"Proceedings of 15th International Conference on Soil Mechanics and Geotechnical Engineering. 2. 1171-1174 (2001)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] 北 勝利, 梶 聡明, 宮下勝也: "盛土-飽和砂地盤系の地震時沈下に関する遠心力載荷実験"土木学会中部支部平成13年度研究発表会講演概要集. 333-334 (2002)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] 北 勝利, 梶 聡明, 宮下勝也, 小野 哲: "飽和砂地盤上の盛土の地震時沈下に関する遠心模型実験"第37回地盤工学研究発表会平成14年度発表講演集. 1813-1814 (2002)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Kita, K. and Yamada, H.: "Centrifuge modeling of seismic settlement of composite breakwaters"Proc. 15th International Conference on Soil Mechanics and Geotechnical Engineering. 2. 1171-1174 (2002)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Kita K., Kaji, T. and Miyashita, K.: "Settlement of embankments on saturated sandy ground due to strong shaking in a centrifuge"Proc. Annual Congress of Chubu-branch, Japanese Society of Civil Engineers (in Japanese). 333-334 (2002)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Kita, K., Kaji, T., Miyashita, K. and Ono, S.: "Centrifuge model tests on seismic settlement of embankments on saturated sandy ground"Proc. 37th Annual Congress of Japanese Geotechnical Society (in Japanese). 1813-1814 (2002)

    • Description
      「研究成果報告書概要(欧文)」より

URL: 

Published: 2004-04-14  

Information User Guide FAQ News Terms of Use Attribution of KAKENHI

Powered by NII kakenhi