FINITE-ELEMENT ANALYSIS OF RIGID PAVEMENTS WITH PARTIAL SUBGRADE CONTACT

A finite-element method programmed for a high-speed computer was developed for determining the stresses and deflections in concrete pavements with partial subgrade contact. The partial contact may result from the pumping and plastic deformation of the subgrade in combination with the upward warping of the slabs. The method is based on the classical theory of thin plates on Winkler foundations. The condition of contact is illustrated by spring analogies. If pumping and plastic deformation of the sub-grade are negligible, the foundation is considered as a set of springs, the tops of which are all at the same elevation. If pumping and plastic deformation exist, the tops of the springs will be at different elevations, and that must be specified before an analysis can be made. The deformed shape of the slabs due to the combined effect of weight and warping is determined first and then used for computing the stresses and deflections due to wheel loads. The accuracy of the method for computing temperature stresses is verified by the assumption that the slab and the subgrade are in full contact and by making a comparison with Westergaard's exact solutions. The validity of the method in predicting the stresses and deflections in actual pavements is indicated by a comparison with the experimental measurements from the AASHO Road Test. The solutions based on partial contact checked more closely with the experimental measurements than with those based on full contact.