Place & Date: Vancouver, British Columbia, Canada, August 2004
Conference: 13th World Conference on Earthquake Engineering
Title: Limits in the gradation curves of liquefiable soils
Authors: Atsunori Numata*, Shinichiro Mori**
*Research Institute of Technology, Tobishima Corporation, Japan
**Ehime University, Japan
ABSTRACT
The authors have paid attention to sand boils, which are ejected due to liquefaction, have conducted a series of site investigation on liquefaction and have collected over 800 samples of ejected soils on liquefied sites during 13 earthquakes in Japan, the United States, the Philippines and Taiwan since the 1987 Chibaken-toho-oki earthquake. Over 800 samples are deemed appropriate for constituting a database for statistical research. This paper elucidates the limits in the gradation curves of liquefiable soil based on this database. First, examples of the curves of soils ejected during an earthquake with typical features are shown for understanding the fundamental nature of the database, as well as the entire figure of the database. Second, the peculiarity of the ejected soils is clarified by the difference between the soil ejected on reclaimed land and that on other kinds of ground in terms of the relationship between fines and clay contents, and ranges of mean grain size. Third, a model of grain size distribution of ejected soil is derived by the relationship between 50% diameter (mean grain size) and modified coefficient of uniformity, which is newly defined in this paper. Finally, statistical analysis of grain size distributions of certain percentages of fines is carried out, and new limits in the gradation curves of liquefiable soils are proposed based upon the results of this statistical analysis.

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