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基质吸力和净平均应力的增大均可引起土体的压缩变形。针对物理性质不同的4种非饱和膨胀土体结合试样收缩曲线和土水特征曲线分析了土体干燥过程中基质吸力和孔隙比的关系。试验结果表明:土体干燥收缩过程中随着基质吸力的增大试样不断发生收缩,当基质吸力增大到某一定值时,基质吸力的增大对试样收缩变形无明影响,称此基质吸力为缩限吸力。并且不同性质土体的缩限吸力不相同,缩限吸力值与土体的塑性指数密切相关。在干燥收缩过程中,当试验的饱和度减小到85%时试样完成了绝大部分收缩,当试验饱和度达到70%时土样的孔隙比基本保持不变。
Substrate suction and net average stress can cause compression deformation of soil. According to the shrinkage curve and soil water characteristic curve of four kinds of unsaturated expansive soil with different physical properties, the relationship between the matrix suction and the void ratio during the drying process was analyzed. The experimental results show that the sample shrinks continuously with the increase of substrate suction during the drying shrinkage. When the substrate suction increases to a certain value, the increase of substrate suction has no effect on the shrinkage of the sample, Substrate suction is the suction force of contraction. The shrinkage and suction of soils with different properties are not the same. The shrinkage and suction values are closely related to the plasticity index of soils. During the drying shrinkage, the specimen completed most of the shrinkage when the test saturation was reduced to 85%. When the test saturation reached 70%, the void ratio of the soil specimen remained almost unchanged.