Cyclic shear behavior of unsaturated volcanic sandy soil under various suction conditions

T. Unno, M. Kazama, N. Sento, R. Uzuoka

Research output: Chapter in Book/Report/Conference proceedingConference contribution

11 Citations (Scopus)


Mudflow type failure of a gentle fill slope occurred at Dateshita in Tsukidate town during the 2003 Sanriku-Minami earthquake in Japan. The flowed fill material was pyroclastic sediment that was classified as a volcanic sandy soil with pumice. This study reports the results of cyclic shear triaxial tests of unsaturated volcanic sandy soil considering suction. Tests were conducted for specimens with different initial suctions and the same dry density under undrained conditions for both air and water. Volcanic sandy soil specimens lost their effective stress under cyclic shear loading even if the degree of saturation is about 70 percent. If the initial suction is lower than the air entry value (AEV) of the soil-water characteristic curve, the effective stress of the specimens became zero or an extremely small value, and stiffness decreased. On the other hand, stiffness did not decrease in cases where the initial suction was higher than the AEV of the soil-water characteristic curve. It is considered that the variation of air distribution pattern in specimens below under the AEV and above the AEV causes the apparent difference in cyclic behaviors. Copyright ASCE 2006.

Original languageEnglish
Title of host publicationProceedings of the Fourth International Conference on Unsaturated Soils
Number of pages12
Publication statusPublished - 2006 Dec 21
Externally publishedYes
Event4th International Conference on Unsaturated Soils - Carefree, AZ, United States
Duration: 2006 Apr 22006 Apr 5

Publication series

NameGeotechnical Special Publication
ISSN (Print)0895-0563


Other4th International Conference on Unsaturated Soils
Country/TerritoryUnited States
CityCarefree, AZ

ASJC Scopus subject areas

  • Civil and Structural Engineering
  • Architecture
  • Building and Construction
  • Geotechnical Engineering and Engineering Geology


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