Coupled modelling of hydro-mechanical behaviour of unsaturated compacted expansive soils

The Barcelona basic model cannot predict the mechanical behaviour of unsaturated expansive soils, whereas the Barcelona expansive model (BExM) can only predict the stressstrain behaviour of unsaturated expansive soils without the water-retention behaviour being incorporated. Moreover, the micro-parameters and the coupling function between micro-structural and macro-structural strains in the BExM are difficult to determine. Experimental data show that the compression curves for non-expansive soils under constant suctions are shifted towards higher void ratios with increasing suction, whereas the opposite is true for expansive soils. According to the observed water-retention behaviour of unsaturated expansive soils, the air-entry value increases with density, and the relationship between the degree of saturation and void ratio is linear at constant suction.