Abstract:
In this research the behavior of a conventional concrete pavement
of uniform thickness and a thickened edge box type pavement with
holes for utility services have been investigated under traffic
wheel loads using finite element technique. The effects of
thickness, width and length of a conventional pavement, thickness
of subbase (of CBR 20) and the subgrade CBR on the pavement
deflection, tensile stress and subgrade pressure were studied. For
the box type pavement the variables included are the end and midslab
thickness, the width and length of slab, the thickness of the
subbase and the CBR of subbase and subgrade. Eight noded
isoparametric brick element has been used for the analysis.
The study shows that for a conventional pavement, the maximum
values of pavement deflection, tensile stress and subgrade pressure
are reduced with an increase in slab thickness. The presence of a
subbase further reduces the above values among which the most
significant reduction takes place in the subgrade contact pressure
value. An increase in pavement width and length of slab also
reduces the tensile stress and deflection. When a better quality
subbase is used, the deflection and tensile stress are reduced.
Similar effects are noticed for a better quality (higher CBR)
subgrade. But the most significant benefit is observed for change
in CBR from 1 to 4.
The pavement deflections of a box-type pavement, particularly with
an equivalent subbase are much lower than the corresponding values
for a conventional pavement. The subbase also substantially reduces
the tensile stress in the pavement. The type of pavement, whether
conventional or box-type, is much more important in reducing
pavement deflection and stresses than the quality of the subbase
expressed in terms of CBR value.
Based on the findings of the present study, a new design rationale
has been suggested for both box and conventional type of pavements,
which will help to make the design of concrete pavements more
economic and rational.
