关键词: 饱和黏性土, 蠕变变形, 固结, 反复加卸载, 初次加卸载

Abstract:

In order to investigate the deformation characteristics of saturated clays due to long-term groundwater withdrawal, several oedometer tests were conducted on the clay samples acquired from the second aquitard unit in the Suzhou-Wuxi-Changzhou area. The creep deformation of the samples under complex loading was studied. The test results have shown that the saturated clay behaves as a creep material obviously under the initial loading; and the relationship between creep deformation and time is approximately linear in a double logarithmic space. The slope of the fitting straight line decreases with the increasing loading; but it shows little changing when the loading is great enough. Saturated clay also exhibits creep deformation when rebounding under initial unloading. The higher the unloading level is, the more remarkable the rebound creep is. The creep deformation can be expressed as a power function of stress and time when rebounding. The test results have also revealed that, under repeating loading, the time when the deformation of samples satisfies the steady requirement decreases with increasing number of cycle. If the maximum loading is smaller than the preconsolidation pressure, the sample becomes elasticity after two cycles; while the sample becomes elasticity after five cycles if the maximum loading equals to the preconsolidation pressure.

Key words: saturated clay, creep deformation, consolidation, repeating loading and unloading, initial loading and unloading