变围压循环荷载下饱和软黏土的变形特性

Deformation characteristics of saturated clay under cyclic loading with variable confining pressure

通过GDS双向振动设备对温州饱和软黏土在部分排水状态下进行了一系列变围压动三轴试验,系统地研究了循环偏应力与循环围压的耦合对加载期间土体变形规律的影响。试验结果表明:软黏土在循环加载期间的轴向应变和体应变均随着循环周次呈现先快后慢的增长趋势,且较高的偏应力幅值与较大的变围压条件η能促进轴向应变和体应变的发展。通过对比变围压与常围压下的累积轴向应变可知:当循环变围压导致循环平均有效主应力大于初始平均有效主应力时,累积轴向应变与变围压条件η呈线性关系;当循环平均有效主应力小于初始平均有效主应力时,累积轴向应变与η之间则不再呈线性关系。

In this study,a series of dynamic triaxial tests with variable confining pressure are carried out on saturated soft clay in Wenzhou under the condition of partial drainage with GDS bidirectional vibration triaxial testing equipment.The effects of coupling between cyclic deviator stress and cyclic confining pressure on the strain of soil during loading are systematically studied.The experimental results show that the axial strain and bulk strain of soft clay first increase rapidly with the cyclic times and then increase slowly during cyclic loading.A higher deviator stress amplitude and a larger variable confining pressure conditionηpromote the development of axial and bulk strains.By comparing the cumulative axial strain under variable confining pressure and constant confining pressure,it is found that it is related to the cyclic mean principal stress and the initial mean principal stress.When the cyclic mean effective principal stress is larger than the initial mean principal effective stress,the cumulative axial strain has a linear relationship with the variable confining pressure conditionη.However,the cumulative axial strain does not have such a relationship withηwhen the cyclic mean effective principal stress is smaller than the initial mean effective principal stress.