Evaluating a new method for simultaneous measurement of soil water retention and shrinkage curves

Abstract

Water retention and shrinkage curves are two important characteristics of unsaturated soils. Conventionally, two curves are separately measured using multiple carefully prepared “identical” soil specimens. However, it is difficult or impossible to fabricate soil specimens with exactly identical stress history. The measurement of two curves was very time-consuming (each up to several weeks). Recently, a new method has been proposed to simultaneously measure two curves through shrinkage tests. The soil suction, water content, and volume during testing are monitored during testing for the construction of the water retention and shrinkage curves. Preliminary shrinkage test results prove that the new method is efficient in the measurement of two curves. In this study, a series of shrinkage tests on two types of soils were performed to evaluate this new method using a new device in which the soil suction, water content, and volume are, respectively, measured using a high-capacity tensiometer, digital balance, and a non-contact photogrammetric method. Test results indicate that the new method significantly reduces the time required for the measurement of two curves from weeks to 1 day. The new method allows simultaneous determination of the two curves using one single soil specimen, which also eliminates the influence of different stress histories on the test results. The axial strain distribution during drying can also be identified based on the reconstructed three-dimensional model of the soil, which is beneficial for examining the soil deformation non-uniformity and stress history. Finally, some discussions on the measurement of two curves using the new method are presented.