Model applicability for prediction of residual soil apparent cohesion

Abstract

Abstract The focus of this paper is on the measurement and prediction of unsaturated shear strength of residual soil as a function of matric suction by utilizing basic soil properties. A total of 19 unsaturated triaxial tests were performed on four groups of undisturbed residual soil specimens with different classifications and compositions. Six compacted specimens were tested and showed lower strength values than those of undisturbed specimens. The cohesion intercept due to matric suction was used to represent the strength contribution of the matric suction, thus accounting for the effect of confining pressure and effective cohesion. The feasibility of three existing models in predicting the apparent cohesion is investigated through comparing computed results to measured data from this paper and literature. A proposed regression equation, developed based on four data sets from the current research and six from the literature, shows an improved ability to predict measured apparent cohesion utilizing basic soil properties. The data set developed herein represent a significant addition to the literature on the unsaturated strength properties of natural residual soil, as sampled from the field.