摘要
长期往复荷载作用下,饱和软黏土强度和刚度的衰减是近海桩基础设计必须考虑的,利用带弯曲元的循环三轴仪对原状饱和软黏土进行了一系列等向固结和非等向固结条件下不排水单调和循环加载三轴试验,并在循环加载过程中通过弯曲元测试土体剪切波速。试验结果表明,在相同的固结条件下,随循环次数的增加和动应力比的提高土体的强度和刚度衰减显著;在相同动应力比作用下较小的有效固结应力和偏压固结减缓了土体刚度的弱化。已有的相对偏应力水平参数不能反映不同固结条件下近海饱和软黏土强度和刚度循环弱化特性,为此引入了动偏应力水平参数,考虑了有效固结应力、固结静偏应力、动偏应力的相互影响,利用动偏应力水平对饱和软黏土的强度和刚度循环弱化特性进行描述。
To design offshore pile foundations,it is necessary to consider the degradation of stiffness and strength of saturated soft clay under long-term cyclic loading.Using the cyclic triaxial test apparatus with bender element system,a series of static and cyclic undrained triaxial tests are conducted on isotropically and anisotropically consolidated natural undisturbed soft clay with the shear wave measured by bender element system during cyclic loading.The experimental results show that under the same consolidated condition,the undrained strength and stiffness of soft clay markedly decrease with the increase of the cyclic stress ratio and the progressive number of cycles.On the other hand,the anisotropic consolidation and lower effective consolidation pressure decelerate the degradation of stiffness under the same cyclic stress ratio.It is unable to show the reduction of stiffness and strength of offshore saturated soft clay correctly under cyclic loading for different consolidation modes by the relative deviatoric stress level.The dynamic deviatoric stress level is introduced considering the effects of effective confining pressure,consolidated static deviatoric stress and dynamic deviatoric stress.The dynamic deviatoric stress level is further used to describe the reduction of stiffness and strength of saturated soft clay under cyclic loading.
出处
《岩土工程学报》
EI
CAS
CSCD
北大核心
2010年第10期1491-1498,共8页
Chinese Journal of Geotechnical Engineering
基金
国家杰出青年科学基金项目(50825803)
关键词
循环荷载
偏压固结
刚度
强度
弱化
动偏应力水平
cyclic loading
anisotropic consolidation
stiffness
strength
degradation
dynamic deviatoric stress level
