MONOTONIC AND CYCLIC BEHAVIOR OF UNSATURATED SANDY SOIL UNDER DRAINED AND FULLY UNDRAINED CONDITIONS

SOILS AND FOUNDATIONS

JUNYA FUKUTANI¹  FUSAO OKA¹  TAICHI YABUKI¹  KOUSUKE NAKASHIMA¹  SAYURI KIMOTO¹ 

[1] Department of Civil and Earth Resources Engineering, Kyoto University

关键词: cyclic loading;    laboratory test;    sand;    suction;    triaxial test;    unsaturated soil;    (IGC: D6);   

DOI  :  10.3208/sandf.51.663

学科分类：建筑学

来源: Japanese Geotechnical Society / Jiban Kogakkai

【 摘 要 】

References(23)Cited-By(1)Changes in air pressure during monotonic and cyclic loading are in some cases important for the behavior of unsaturated soil. For example, in order to investigate the stability of embankments and slope failure during earthquakes, it is necessary to consider the effect of the pore air or the pore gas pressure as well as the pore water pressure and the interaction between the soil and the pore fluids. In the present study, we carried out a series of monotonic and cyclic loading tests on sandy soil used for the improvement of river embankments. The effects of the initial suction, the confining pressure, and the degree of compaction under fully undrained conditions, namely, constant water and constant air shearing tests, as well as under drained conditions for both air and water, were studied. For the stress variables of the unsaturated soil, the skeleton stress was used to describe the experimental results and was defined as the difference between the total stress tensor and the average pore pressure of water and gas (Oka et al., 2010). From the monotonic and cyclic test results, we found that the stress-strain behavior of unsaturated sandy soil strongly depends on the initial suction, especially under fully undrained conditions, due to the difference in pore pressures. In the cyclic loading tests under fully undrained conditions, the mean skeleton stress decreased due to the increase in air pressure and led to the failure of the specimen in the case of a lower level of initial suction. In addition, the test results exhibited the strain rate effect on the stress-strain behavior during cyclic loading under fully undrained conditions.

【 授权许可】

Unknown