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为探究益阳膨胀土次固结系数变化规律,研究土体长期压缩变形特性,得到方便工程运用的本构模型,以单轴固结试验为基础,延长受载周期,取益娄高速膨胀土进行长期一维固结压缩试验,探究固结压力和干密度对膨胀土样长期压缩特性的影响。试验结果表明,土样干密度对次固结系数影响相对较小,具体变化规律表现为次固结系数随干密度的增大而减小。相比之下,固结压力对次固结系数影响较大,且次固结系数随固结压力增大而增大,并呈现对数函数关系。在分析各因素对膨胀土长期压缩特性影响的基础上,建立了益阳膨胀土非线性本构模型,得到了益阳膨胀土压缩量与时间、固结压力和干密度等的关系。本构模型由主固结部分和次固结部分组成,按照此本构关系得出的计算结果与规范修正法结果几乎一致,并且从物理意义、固结过程划分等方面更显清晰。
In order to explore the regularity of secondary consolidation coefficient of Yiyang expansive soil and to study the long-term compressive deformation characteristics of the soil, the constitutive model for convenient engineering application is obtained. Based on the uniaxial consolidation test, the loading cycle is prolonged to take advantage of Lou-speed expansive soil Long-term one-dimensional consolidation compression test to investigate the influence of consolidation pressure and dry density on long-term compression characteristics of expansive soil samples. The test results show that the dry density of soil sample has a relatively small influence on the secondary consolidation coefficient, and the specific variation is that the secondary consolidation coefficient decreases with the increase of dry density. In contrast, the consolidation pressure has a significant effect on the secondary consolidation coefficient, and the secondary consolidation coefficient increases with the consolidation pressure and shows a logarithmic function. Based on the analysis of the influence of various factors on the long-term compressibility of expansive soils, a nonlinear constitutive model of expansive soils of Yiyang was established, and the relationship between the amount of compression and the time, consolidation pressure and dry density of the expansive soils of Yiyang was obtained. The constitutive model is composed of the main consolidation part and the secondary consolidation part. The calculation results obtained according to this constitutive relation are nearly identical with those of the normalized correction method, and are more clear from the physical meaning and the consolidation process.