Journal of Natural Disaster Science

SHEAR DISPLACEMENT BEHAVIOR OF SANDY SOILS IN DIFFERENT STATES OF SATURATION AND THE SEISMIC COEFFICIENT IN CYCLIC-LOADING RING-SHEAR TESTS

Fawu WANG
Graduate Student, Graduate School of Science, Kyoto University
and
Kyoji SASSA
Professor, Disaster Prevention Research Institute, Kyoto University

(Received 3 September, 1997 and in revised form 16 March, 1998)

Abstract

To study the shear displacement behavior of sandy soils under cyclic-loading, we conducted a series of tests on dry and saturated silica sand at different seismic coefficient ratios, K/Kc being the ratio of the seismic coefficient to the critical seismic coefficient necessary to cause shear failure in a slope. Test results showed that in the dry condition, shear displacement increased with the magnitude of K/Kc. A large shear displacement or high-mobility phenomenon was generated at a high BD Value (the pore-pressure response to the increment of normal stress in the undrained condition) in the saturated condition when K/Kc was larger than a critical value. For saturated silica sand with a low BD Value of 0.20 at K/Kc=2.0, no high-mobility phenomenon was generated, but a build-up of excess pore pressure was observed. For the field application, Osaka-group coarse, sandy soil taken from the Takarazuka Golf Club landslide, was used in a test of the same type, which showed high soil mobility.

Key words

ring-shear test, cyclic-loading, seismic coefficient ratio, shear displacement, sandy soils, high-mobility