Volume 38, Issue 6 (November 2010)
A Study on the Influence of Measurement Procedures on Suction-Water Content Relationship of a Sandy Soil
Soil suction and its relationship with water content (gravimetric or volumetric) are inevitable in the study of unsaturated soil mechanics. Suction-water content relationship (designated as SWR) is an important input parameter for the mathematical modeling of unsaturated soil response pertained to physico-mechanical, hydraulic, and volume change behavior and hence needs to be accurate and unambiguous. There are two commonly adopted procedures for establishing the SWR. In the first method (designated as continuous measurement), continuous drying suction measurements are performed on the same soil sample, starting from a high water content (corresponding to insignificant suction), which is termed as soil-water characteristic curve. In the second method (designated as spot measurement), remolded soil samples are packed at different compaction states, varying in unit weight and water content, on which suction measurements are performed. It is noted that there is no comparison and critical evaluation of these two procedures adopted for determining SWR. Such a study is important as the particle rearrangement in the soil samples undergoing a drying process might be different from that of the reconstituted/remolded samples. Therefore, the present study attempts to understand the uniqueness of SWR obtained by using two procedures for a locally available sandy soil. In this study, tensiometer and a capacitance probe have been used for measuring suction and volumetric water content, respectively. The study indicates that SWR established by using different procedures may not be unique and there is a need to highlight it while reporting such relationship for the soil.