AN ELASTOPLASTIC MODEL FOR UNSATURATED EXPANSIVE SOILS BASED ON SHAKEDOWN CONCEPT

It is important to model the behaviour of unsaturated expansive soils subjected to hydromechanical loadings, because these wetting and drying cycles alter significantly their hydromechanical behaviour which may cause a huge differential settlement on the foundations of individual buildings, pavements, dams, etc. From experimental observations, these expansive soils can generally reach a final equilibrium state at the end of the suction cycles where the soil behaviour can be supposed elastic. In this context, this paper presents an analytical method based on shakedown concept for the hydromechanical behaviour of expansive soils. The required parameters of the shakedown-based model are calibrated by the experimental results obtained for bentonite/sand mixtures subjected to cyclic suction loadings in an oedometric test. The comparison between the experimental results and the modeling demonstrates the capacity of the proposed shakedown-based model to simulate the hydromechanical behaviour of unsaturated expansive soils.