为了更加真实地描述地基饱和软黏土在长期交通循环荷载作用下的永久变形特性,借助GDS变围压动三轴试验系统对温州饱和软黏土开展了一系列恒定围压应力路径(CCP)以及变围压应力路径(VCP)下的部分排水循环加载试验,重点分析了循环动应力比(CSR)、应力路径(α)及其长度(L)对饱和软黏土永久轴向应变的影响。试验结果表明:在给定的循环次数(N)下,永久轴向应变随着CSR的增大和α的减小而增大,可分别采用指数函数和对数函数描述永久轴向应变与CSR和α之间的关系。基于试样经历10 000次循环后的永久轴向应变,通过归一化处理发现归一化永久轴向应变(εpa,10 000/εp,CCPa,10 000)与归一化应力路径长度(L/LCCP)和归一化平均主应力幅值(pampl/pamplCCP)之间分别呈对数和线性关系且与CSR无关。进一步构建了考虑CSR、α以及N综合影响的对数型经验模型并对不同应力路径下的永久轴向应变进行了预测,预测结果与实测值呈现出较好的一致性。
Abstract
Partially drained CCP (constant confining pressure) and VCP (variable confining pressure) cyclic triaxial tests were carried out on Wenzhou soft clay by using GDS (Global Digital Systems) to investigate the permanent deformation behavior of saturated soft clay in subgrade under long-term traffic load more realistically.Special attention was paid to the influences of cyclic stress ratio (CSR),stress path (α) and length (L) on the permanent axial strain of saturated soft clay.The test results unveiled that at a give cycle number (N),the permanent axial strain increased with the increase of CSR and the decrease of α,which can be described by exponential function and logarithmic function respectively.The normalized permanent axial strain undergone 10,000 cycles (εpa,10 000/εp,CCPa,10 000) was in a logarithmic relationship with the normalized stress path length (L/LCCP),and a linear relationship with the normalized mean principal stress amplitude (pampl/pamplCCP),regardless of the CSR values.Furthermore,a logarithmic empirical model considering the combined effect of CSR,α,and N was established to predict the permanent axial strain under different stress paths,and the predicted results were in good agreement with the measured deformation.
关键词
饱和软黏土 /
应变累积特性 /
GDS变围压动三轴试验 /
部分排水应力路径 /
永久轴向应变 /
经验模型
Key words
saturated soft clay /
strain accumulation characteristic /
GDS dynamic triaxial test with variable confining pressure /
partially drained stress path /
permanent axial strain /
empirical model
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基金
安徽省自然科学基金项目(1908085QE215);宿州学院教授/博士项目(2016jb05)
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