饱和黏性土蠕变变形试验研究  

Experimental study of creep deformation of saturated clay

作　　者：张云[1] 薛禹群[1] 吴吉春[1] 何佳佳[1] 王惠敏[1] 

机构地区：[1]南京大学地球科学与工程学院,南京210093

出　　处：《岩土力学》2011年第3期672-676,683,共6页Rock and Soil Mechanics

基　　金：国家自然科学基金项目(No.40772168);国家杰出青年科学基金项目(No.40725010)

摘　　要：结合苏锡常地区地面沉降研究,用单向固结仪研究饱和黏性土在复杂荷载作用下的蠕变变形特征。试验土样取自苏锡常地区第2弱透水层。研究结果表明,在初次加载时黏性土具有明显的蠕变性,在双对数坐标中蠕变变形与时间呈直线关系,且直线斜率随荷载水平增大而减小,但在荷载水平达到一定值后斜率变化不大;在初次卸载时黏性土仍有明显的回弹蠕变,特别是在卸载水平较高时,卸载回弹蠕变变形与应力和时间的关系仍可用幂函数表示;在循环荷载作用下,加卸载达到变形稳定的时间随循环次数增加而减小。当循环荷载最大值小于土样的先期固结压力时,土样在2次加卸载循环后达到弹性变形状态;当循环荷载最大值等于土样的先期固结压力时,土样在5次加卸载循环后达到弹性变形状态。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.

关 键 词：饱和黏性土 蠕变变形 固结 反复加卸载 初次加卸载 

分 类 号：TU411[建筑科学—岩土工程]