Abstract
This study aimed at evaluating the unsaturated shear strength of compacted sand-clay liner for a wide range of suction. For this purpose, effective shear strength parameters were determined using direct shear tests. The soil-water characteristic curve (SWCC) was determined over the entire range of suction. The bimodal shape of SWCC has been detected and appropriate bimodal fitting approaches were applied. A new prediction model has been proposed using the profile of SWCC and effective shear strength parameters to predict the unsaturated shear strength function (USSF) in terms of unconfined compression strength. For validation, a series of unconfined compressive strength (UCS) tests were performed for specimens at different levels of suction. The model predicts USSF of the soil mixtures with bimodal pore series and found in a good agreement with measured data. The model assists in evaluating USSF using simple tests instead of running a time consuming unsaturated shear strength tests..