Routine pavement methods are mechanistic-empirical design methods, based on linear elastic calculations. Usually, the only rutting criterion to be used concerns the subgrade soil, and consists in limiting the vertical elastic strains at the top of the subgrade. Rarely is a criterion applied for the unbound granular layers although Dawson and Kolisoja (2004) have shown that in roads with thin bound layers, the road’s rutting will largely be the consequence of plastic deformation in the granular layers. Similarly, it is rare for a plastic criterion to be used in design probably because of the much greater difficulty in computing plastic strain fields.
Advanced pavement models are based on the main tests for unbound granular materials: the monotonic triaxial test and the repeated load triaxial test (this test and the models’ calibrations are presented in Chapter 10).
These models are split in four categories:
• Analytical models;
• Plasticity theory based models;
• Visco-plastic equivalent models; and
• Shakedown models.
