Estimation of Water Retention Curve for Unsaturated Fine Soils


1 Asociate Profesor Amirkabir University of Technology, Tehran, Iran

2 Civil Engineering Department,University College of Engineering, University of Tehran, Iran

3 Civil and environmental Engineering Department,Amirkabir University of Technology, Tehran, Iran


In order to obtain the soil water retention curve of an unsaturated soil which is defined as the relationship between water content and suction, extensive laboratory tests are essential. These laboratory tests are usually costly and time consuming. Moreover, for most practical problems, it has been found that approximate unsaturated soil properties are adequate for analysis. Thus, empirical procedures to predict unsaturated soil parameters would be invaluable. The water retention curve can be measured or predicted based on soil index properties. Estimation based on index properties is highly desirable due to its simplicity and low cost.

In this paper, the constant parameters of well-known Van-Genuchten and Fredlund-Xing equations based on index properties of fine soils are derived. The comparisons show that the curves predicted by these models are in a good agreement with the experimental results.