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为了探究原状黄土土-水特征曲线与土样微观结构之间的关系,对甘肃黑方台不同埋深Q_3原状黄土进行了基本物理指标的测试,张力计法测得其土-水特征曲线,并利用Fredlund&Xing模型对土-水特征曲线进行了拟合。采用光学显微镜和Photoshop合成技术获得了不同埋深土样的微观结构,统计得到孔隙累积级配曲线和分布曲线。结果表明不同埋深Q_3黄土,颗粒组成相同;其土水特征曲线,在饱和区,相同基质吸力下土样埋深(干密度)越大,体积含水率越小;而在过渡区,体积含水率则越大;在残余区,土水特征曲线几乎重合,这种差异主要是由土样的孔隙分布特征所控制。最后根据土样的分布曲线建立了黄土土水特征的本构关系,其预测值同实测值基本吻合。
In order to explore the relationship between undisturbed loess soil-water characteristic curve and soil microstructure, the basic physical indexes of Q_3 undisturbed loess with different burial depth at Heifangtai of Gansu Province were tested. The soil-water characteristic curve was measured by tensiometer method, The soil-water characteristic curve was fitted using the Fredlund & Xing model. Microstructures of soil samples with different burial depths were obtained by optical microscopy and Photoshop synthesis. The accumulated gradation curves and distribution curves were obtained. The results show that the composition of the loess with different depths is the same. The soil water characteristic curve shows that the greater the soil depth (dry density) and the smaller the volumetric water content under the same substrate suction in the saturated zone and the same matrix, The greater the rate; in the remaining area, the soil-water characteristic curve almost coincide, the difference is mainly controlled by the pore distribution characteristics of soil samples. Finally, according to the distribution curve of soil samples, the constitutive relation of soil-water characteristic of loess is established, and its predicted value is in good agreement with the measured value.