Swelling Pressure Prediction of Compacted Unsaturated Expansive Soils

Abstract

Generally, expansive soils undergoes significant volumetric deformation, which causes structural damages to existing infrastructures. Damages due to expansive activities are noticeable in pavements, buildings, earth dams, retaining walls etc. To estimate swelling stress, accurate assessment of soil absorption of water over time, with respect to soil volumetric change is required. However, the time frame requires for completion of swelling cycle is relatively long. With this in view, several attempts with great success have been made by researchers to predict swelling pressure of expansive soils using soil mechanics index properties. In this study, the interrelation between unsaturated soil mechanics property i.e. Matric suction () and geotechnical soil indexes were utilized to develop three predictive multi-regression equation for swelling stress. Series of Atterberg limit tests, matric suction tests, free swell index (FSI) tests and zero swelling tests (ZST) were performed to obtain the dependent and independent variables for the multi-regression analysis. Based on the experimental results, empirical relationships were developed to determine swelling stress as a function of matric suction, gravimetric moisture content (GMC), FSI, dry density and plasticity index using mathematical software package (NCSS11). The developed predictive multi-regression models were used to estimate the experimental swelling stress (. The scattered plot showed good agreement between the measured and predicted data, with coefficient of determination (R2) and mean square error (MSE) of 0.9443, 0.9793, 0.9310 and 0.0051%, 0.0021% and 0.0067% for models 1, 2 and 3 respectively.