Significance of Soil Suction and Soil Water Characteristic Curve Parameters

Abstract

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.

Modulus−suction−moisture relationship for compacted soils

“…Matric suction is the potential energy of soil water created by capillary tension between soil particles and pore water and surface adsorptive forces. Matric suction constitutes about 40%-75% of total suction in fine-grained soils (Sivakumar Babu et al 2005).…”

“…The filter paper method was performed in accordance with ASTM D 5298 (ASTM 2003). This method was selected because: (i) it is capable of measuring a wide range of matric suctions (i.e., from 10 kPa to 10 MPa), (ii) it is relatively simple and inexpensive, and (iii) it has been widely used in geotechnical engineering practice (Fredlund and Rahardjo 1993;Houston et al 1994;Melgarejo et al 2002;Sivakumar Babu et al 2005).…”