An effective stress-based DSC model for predicting the coefficient of lateral soil pressure in unsaturated soils

In this study, an analytical model is developed to establish a framework for predicting the coefficient of lateral soil pressure in unsaturated soils. To this end, the disturbed state concept (DSC) is implemented along with the concept of effective stress for unsaturated soils. Accordingly, upper and lower limits are considered for the structural disturbance of the soil during hydromechanical loading, and a suction-dependent analytical framework is proposed for calculating continuous variations of the coefficient of lateral soil pressure, from the at-rest to active state of the soil, against the effective vertical stress parameter. The functionality of the proposed model is verified against experimental results obtained from a series of laboratory unsaturated drained tests conducted on two different soil materials (a Sand-Kaolin mixture and Firouzkouh Clay) with two initial void ratios. Quantitative comparisons show excellent conformance between the predicted and experimental data. A practical example of calculating lateral soil pressure on a gravity retaining wall is also presented, in which the results obtained from the model presented in this study and the conventional classic approach of calculating the lateral soil pressure on retaining walls are compared. It is hoped that the results of this study can help researchers and designers to obtain improved values of lateral soil pressure in unsaturated soil.