In the European project SAMARIS, the predictions obtained with ORNI have been compared with the response of a low traffic pavement tested on the LCPC pavement test track. The pavement consisted of:
• a bituminous concrete wearing course, with an average thickness of 66 mm;
• A 50 cm thick granular base and sub-base (crushed gneiss);
• A clayey sand subgrade (thickness 2.20 m), resting on a rigid concrete slab.
As in the previous example (Section 11.4.5) the pavement was instrumented to measure strains, temperatures and water contents in the various layers. The loading consisted in applying 1.5 million heavy vehicle loads (dual wheels, with a load of 65 kN).
In the modelling of the resilient behaviour (with CVCR), the bituminous concrete and the soil were assumed linear elastic, and the UGM was described using the anisotropic Boyce model (Eq. 9.13). The bituminous concrete moduli (function of temperature and loading frequency) were determined from complex modulus tests, the UGM and soil parameters from repeated load triaxial tests.
In the modelling with ORNI, it was assumed that no permanent deformations occur in the thin bituminous layer. The permanent deformations of the UGM and of the soil were described using the empirical model of Gidel et al. (2001), with model parameters determined from repeated load triaxial tests, at two water contents for the UGM (w = 4% and 5%), and one water content for the soil (w = 11%).
Figure 11.17 shows the finite element meshes used to determine the resilient behaviour with CVCR (in 3D), and then the permanent deformations (in 2D).
|
Fig. 11.17 Finite element meshes used for the modelling of the experimental pavement |
