摘要
针对饱和黏土,利用土工静力-动力液压三轴-扭转多功能剪切仪,通过不固结不排水条件下的循环扭剪和竖向-扭转耦合试验,着重探讨了大应变情况下分级加载历史和循环应力耦合对动剪切模量与阻尼比等动力特性的影响。对试验结果的分析表明:采用多个试样单级加载与采用一个试样分级加载试验得到的初始骨干曲线、动剪切模量与阻尼比都较为一致,采用分级加载试验测定动剪切模量与阻尼比是可行的;耦合循环应力中的轴向偏差应力对扭转向应力-应变滞回圈的倾斜程度及动剪切模量与阻尼比都有显著影响,尤其当扭转向循环剪应力较小时,可以认为轴向偏差应力的大小控制着动剪切模量的增大量,受扭转向剪应力的影响,轴向应力–应变滞回圈的变化模式较为复杂。
The apparatus for static and dynamic universal triaxial and torsional shear tests was employed to perform cyclic torsional shear tests and coupled vertical and torsional shear tests on soil under unconsolidated-undrained conditions. Through a series of tests on saturated clay, the effect of stepped loading history and coupled cyclic stress on dynamic shear modulus and damping ratio under large strain (〉10^-3) was examined. It was indicated that the stepped loading method could be used to determine the dynamic shear modulus and the damping ratio since the initial backbone curve, dynamic shear modulus and damping ratio obtained from single-step loading tests by use of many clay samples were consistent with those obtained from stepped loading tests by use of one clay sample. There was an obvious effect of cyclic axial deviatoric stress on the obliquity of stress-strain hysteresis loops as well as on the dynamic shear modulus and the damping ratio. Especially under the low cyclic torsional shear stress, the increments of dynamic shear modulus seemed to be controlled by the magnitude of axial deviatoric stress. The variations of axial stress-strain hysteresis loops were complicated due to the influences of cyclic torsional shear stress.
出处
《岩土工程学报》
EI
CAS
CSCD
北大核心
2008年第4期518-523,共6页
Chinese Journal of Geotechnical Engineering
基金
国家自然科学基金资助项目(50579006,50179006)
关键词
饱和黏土
动剪切模量
阻尼比
分级加载试验
耦合循环应力
saturated clay
dynamic shear modulus
damping ratio
graded loading test
coupled cyclic stress