Deformation characteristicsof overconsolidated clay sheared under constant and variable confining pressure
Deformation characteristicsof overconsolidated clay sheared under constant and variable confining pressure
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常变围压下超固结粘土剪切变形特征
DOI：
10.1016/j.sandf.2016.04.009
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发表时间：
2016
影响因子：
3.7
通讯作者：
Wang Peng
中科院分区：
文献类型：
--
作者：
Gu Chuan;Wang Jun;Cai Yuanqiang;Sun Lei;Wang Peng
粘土路基的交通致沉降研究通常基于单向循环三轴试验。大多数粘土的单向三轴循环试验都是在正常固结试样上进行的，在恒定围压和不排水条件下进行的。然而，研究发现，交通荷载引起的变应力场不仅包括循环轴向应力，还包括循环水平应力和剪切应力。有时部分路基土超固结，而不是正常固结，在长期交通荷载下通常允许孔隙水的排水。基于此，对30个试件进行了部分排水条件下的单向循环三轴试验，重点研究了超固结比、循环应力比和循环围压对饱和黏土变形特性的耦合效应。试验结果表明，无论试样是超固结还是正常固结，增大循环围压幅值都会显著加速试样永久体积应变和轴向应变的积累。无论OCR和CSR值如何，变围压试验获得的永久轴向应变与定围压试验获得的永久轴向应变之间存在线性关系。考虑OCR值的影响，还建立了循环围压幅值增量与永久轴向应变增量之间的定量关系。
The traffic-induced settlements of clay subgrade are usually investigated based on one-way cyclic triaxial tests. Most one-way triaxial cyclic tests on clays have been carried out on normally-consolidated samples, with a constant confining pressure and under undrained conditions. However, it has been found that the varying stress field induced by traffic loading consists of not only cyclic axial stresses, but also cyclic horizontal stresses and shear stresses. Sometimes part of the subgrade soil is overconsolidated, rather than normally-consolidated, and the drainage of pore water is usually allowed under long-term traffic loading. Recognizing this, a series of one-way cyclic triaxial tests was performed on 30 specimens under partially-drained conditions, and the emphases were placed on the coupling effects of the overconsolidation ratio, the cyclic stress ratio, and the cyclic confining pressure on the deformation characteristics of the saturated clay. The test results show that increasing the amplitudes of cyclic confining pressure will cause a remarkable acceleration in the accumulation of both the permanent volumetric strain and the axial strain, whether the sample is overconsolidated or normally-consolidated. A linear relationship is found between the permanent axial strains from tests with variable confining pressure and their counterparts obtained from tests with constant confining pressure, regardless of the OCR and CSR values. A quantitative relationship, which considers the effects of the OCR values, is also established between the increments in cyclic confining pressure amplitudes and the increments in permanent axial strain.