01594145

Component

The water retention and shrinkage curves are two important characteristics of unsaturated deformable soils. Conventionally, multiple soil specimens are needed to separately establish the two relationships without considering the influence of different stress histories on soil behavior. When soil water retention curve is measured, the soil is assumed to be rigid with no volume change. For the shrinkage curve, at present, there is still no simple and reliable method to accurately measure soil volume change during drying. In addition, it is very time-consuming to measure the two curves. Typically several weeks are needed to measure each curve. As a result, there is a great need to develop a method which can quickly and reliably measure water retention and shrinkage curves for unsaturated deformable soils. In this study, a simple device is designed to overcome the above limitations in the existing water retention and shrinkage curves measurement methods. The soil water content variations during shrinkage test are monitored using a digital balance. A high-suction tensiometer is used to measure soil suction. A non-contact photogrammetric method is proposed to accurately measure the soil volume during drying. The new device allows simultaneously measuring the water retention and shrinkage curves using one single soil specimen, which eliminates the influence of different stress histories on the final results. The proposed method also reduces the testing time from several weeks to a couple of days with more accurate measurements. A series of tests was performed on a deformable soil with different stress histories to validate the proposed system. Test results indicate that the water retention and shrinkage curves could be significantly influenced by the soil stress histories which are neglected in the existing methods.

This paper was sponsored by TRB committee AFP60 Standing Committee on Engineering Behavior of Unsaturated Soils.

01584066

16-6527

English

20p

2016

Transportation Research Board 95th Annual Meeting

Digital/other

Figures; References; Tables

Measuring instruments; Photogrammetry; Shrinkage; Soil tests; Soil water; Tensiometers; Unsaturated soils

Retention curves; Stress history

Geotechnology; Highways

Transportation Research Board Annual Meeting 2016 Paper #16-6527

TRIS, TRB, ATRI

Jan 12 2016 6:53PM