Significance of Soil Suction and Soil Water Characteristic Curve Parameters

Soil Water Characteristic Curves (SWCC) of unsaturated soils have considerable importance in analysis of geotechnical engineering problems. In these analyses, it is necessary to make a distinction between the components of total suction in terms of solute and matric suctions, which is generally ignored in practice. In the present study, suction characteristics of two compacted clayey soils are measured using filter paper method (ASTM D 5298-94), which is useful in this regard. The experimental results show that consideration of only matric suction instead of total suction is conservative as it constitutes about 25 to 60 % of total suction in clay soils. Theoretical models were fitted to experimental results, and it is demonstrated that the model parameters are different in terms of total suction and matric suction. The results show that measurement of both the components of suction using the filter paper method is simple and useful in engineering analysis