MODELIZATION OF FLEXIBLE PAVEMENTS WITH CESAR-LCPC FEM PROGRAM

Twelve flexible structures of the French Design Manual for Light Traffic Roads are analysed using the fem program Cesar (French Laboratoire Central des Ponts et Chaussees). They correspond to two levels of performance (good and mean) for unbound gravel and for platform, and to three traffic levels. Two calculations under axi-symmetrical conditions are performed, assuming elastic-linear or Boyce's elastic non-linear behaviour. The results obtained using these two laws are compared. The domains of variation of stresses are analysed with regard to Mohr-Columb's plasticity criteria. The main results are: (1) plasticization of unbound materials only occurs for the linear model; (2) the most interesting results for design (horizontal strain at the bottom of bituminous layer, and vertical strain at the top of soil layer) are largely influenced by the behaviour law. Thus, the linear model gives values varying approximately from 35% to 90% of those obtained by the non linear model, according to the structure. For the covering abstract see IRRD 883133.