3-Dimensional Finite Element Analysis of Cracking

Resumo

Pavement structural analysis aims at computing the pavement response under traffic and environmental loading. Excessive stresses induced by these two loading parameters lead to various types of distresses. One of the mos t important distresses is cracking. This paper focuses on traffic load induced cracking that either initiates at the bottom of bituminous pavement layers propagating upwards (bottom-up) or starts at the surface growing downwards (top-down). There is a need to investigate these types of cracking by establishing analytical models capable of simulating failure mechanisms, with the view to acquire a better understanding of the pavement behaviour so that the selection and design of maintenance treatments may be optimised. To this end, this paper presents three-dimensional models that were used for a detailed behavioural modelling of a pavement and for analysing both the distribution of stresses at the vicinity of single cracks and their effect on the overall pavement strength. The models were developed using LUSAS©, a general-purpose finite element computer program, and calibrated using Falling Weight Deflectometer (FWD) field data. A good convergence was achieved between the FWD measured deflections and those calculated by the models. Further analyses showed that the presence of cracking does not affect significantly the computed deflections but primarily the stress regime within the bituminous layer. In addition, the analyses demonstrated that top -down cracking may have a significant effect on the distribution of stresses within the bituminous layers. It should therefore be analysed as a structural defect, like bottom-up cracking.