单向循环荷载下超固结软黏土的永久变形特性

为研究超固结饱和软黏土在单向循环荷载作用下的永久变形特性,采用GDS动三轴,对不同超固结度的温州饱和软黏土试样进行了一系列单向循环加载试验,分析了循环动应力水平以及超固结比对饱和软黏土永久轴向应变的影响。试验结果表明:在单向循环加载作用下,超固结饱和黏土存在循环动应力阈值,通过几何作图法综合确定温州饱和软黏土的循环动应力阈值为0.59~0.68,可作为软土路基沉降控制的标准。基于试验结果并结合指数模型,构建了可以综合考虑循环动应力水平、超固结比以及循环次数的饱和软黏土永久轴向应变显式计算模型,适合饱和软黏土地基在交通循环荷载下的累积变形分析。

Permanent Deformation Behavior of Overconsolidated Soft Clay under One-way Cyclic Loading

To investigate the permanent deformation behavior of overconsolidated soft clay under one-way cyclic loading, through the GDS cyclic triaxial apparatus, a series of undrained one-way cyclic triaxial tests were performed on Wenzhou soft clay with different overconsolidated ratios (OCRs). The influence of cyclic stress level and OCRs on permanent axial strain of saturated soft clay were analyzed. The results show that: the possible existence of the threshold cyclic stress ratio under the one-way cyclic loading is confirmed. The value of the threshold stress ratio is 0.59~0.68, which is determined by geometrical drawing approaches and can be used as a criterion of settlement control for soft subgrades. Based on the experimental results and the exponential model, a simplified permanent axial strain model that explicitly considers the effects of cyclic stress ratio (CSR), OCR and cyclic number(N) is established, which is suitable for analyzing the cyclic accumulative deformation of soft foundation of traffic engineering.