| A combined finite element-boundary element method is presented for the analysis of distresses in pavements subjected to mechanical and environmental effects. The three major distresses affecting the serviceability of the pavement system are the temperature, moisture, and the applied mechanical loads. First, a coupled heat transfer-moisture transfer analysis for the finite element region is performed. Using a three-dimensional relationship between temperature, moisture, and modulus of elasticity of a cohesive soil, the distribution for the modulus of elasticity in the soil medium supporting the pavement structure is evaluated. A coupled boundary element-finite element stress analysis which uses the evaluated modulus of elasticity distribution is performed.;Also, the separation of the concrete pavement slab from its supporting subgrade is evaluated. Two mechanisms for separation were considered. First, the separation due to curling of the concrete slab under the combined mechanical and thermal loads. Second, the separation enhanced by the existence of pavement joints along the slab. The latter type of separation is stochastic. The model considers separation to take place when the applied shear stress exceeds the slip resistance stress in the thin layer of frictional interface elements separating the slab from its supporting subgrade. The separation enhanced by pavement joints was investigated by, first, analyzing the joint with its load transfer device. The resulting stiffness of the detailed joint was, then, condensed and assigned to the joint elements of the global finite element - boundary element model. The results of the analyses were, finally, combined by a probabilistic investigation which predicted the reliability of the pavement system against damage due to separation and the consequent deflections and stresses. |
