Validation of an extended critical state model using the mechanical behaviour of an agricultural soil

A validation of an extended critical state model was conducted using a heavy agricultural clay soil from Quebec Province, eastern Canada. The numerical model used for this purpose simulated the behaviour of Sainte-Rosalie clay under triaxial compression and one-dimensional compression loading paths. Under triaxial compression, simulations were done for three soil suctions: 0, 300, and 500 kPa. Under one-dimensional compression, simulations were done for suctions 0 and 300 kPa. The model used five parameters while simulating soil mechanical behaviour under saturated condition. Three additional parameters were required for simulating soil mechanical behaviour under unsaturated condition. Results of simulations were then compared to those of laboratory tests. Experimental data compared well with simulation results. It was found that the model reasonably predicted soil behaviour under both saturated and unsaturated conditions. However, some discrepancies arose in both soil conditions: the model predicted an earlier rupture in each case of triaxial compression and it failed to reach the smallest void ratio obtained during one-dimensional compression. These small divergences were attributed to the fact that numerical development of the tested model was based on densified sand behaviour.