| Hefei area of unsaturated expansive soils are widely distributed, expansive soil has significant swell and desiccation shrinkage characteristics, so find out the mechanism of the expansive soil to solve the problem of expansive soil development area of the project is of great significance.In this paper,6 kinds of unsaturated expansive soil in hefei area as the research object have been researched on the shrinkage properties, microscopic characteristics and the characteristics of soil water properties.In order to study the shrinkage properties of expansive soil, the shrinkage test of different initial dry density of saturated soil sample have been carried out.We studied the relationship between the linear shrinkage ratio and water content (δ-w) and the relationship between void ratio and water content (e-w). Based on the result of curve fitting to shrinkage curves, we calculated the shrinkage limit, shrinkage coefficient, maximum linear shrinkage of expansive soil and the relationship between kinds of fitting parameters and initial dry density.To search the microstructure characteristics of tested sample, the sample in a series of tests.We get the sample’s particle size of the cumulative distribution curve by laser method test, analyses the sample particle size distribution.On the basis of mercury injection experiment (MIP), got the sample the aperture of the cumulative distribution curve, pore size distribution of the sample are analyzed; By scanning electron microscope (SEM) technology on the microstructure morphology characteristics of the sample was analyzed.In the study of soil water characteristics, in this paper, the soil water characteristic curve was introduced in detail, and its influencing factors and measurement methods were reviewed.Dialysis method and the filter paper method were introduced in detail, Using these two methods to experimental study on the sample, we obtained the measured data of the soil water characteristics of the sample, and through the fitting model fitting analysis of test results is performed, thus get the relatively complete soil water characteristic curve and the fitting parameters.Was derived based on the Kelvin’s theory of capillary, We obtained the soil water characteristic curve prediction theory equation based on the soil pore size distribution of and gave the corresponding assumptions, the test with the soil water characteristic curve is forecasted, and the predicted results and measured data for the study of comparative analysis. |
