Model predictions of hydro-mechanical coupling in unsaturated crushable soils

The paper investigates some signatures of hydro-mechanical coupling in unsaturated crushable soils. We use the framework of unsaturated breakage mechanics (Buscarnera & Einav 2012) focusing on the role of suction on the yielding threshold, as well as on the evolution of the water retention properties during crushing. The influence of the free energy potential on the predicted couplings is studied and the properties of the constants that control the expansion of the elastic domain are discussed. The model is finally used to simulate a series of suction-controlled one-dimensional compression tests on sand. The simulations confirm that, while suction effects causes a shift of the yielding threshold, the evolving particle grading introduces simultaneous changes in the retention curve and, hence, in the degree of saturation. As a result, it is suggested that the high-pressure compaction of unsaturated granular compounds is likely to be affected by such coupling effects and requires to take into account the co-evolution of compressibility and retention properties.