Volume 13, Issue 1 (January 1985)
Evaluation of In-Situ Pavement Moduli from Deflection Measurements
At present, there is no direct solution that provides the pavement in-situ layer moduli from deflection measurements. Current methods evaluate the pavement layer moduli from deflection measurements using either empirical approaches or layered elastic computer programs with iterative solutions. In this study mechanistically based typical curves are developed to evaluate the moduli of the pavement layers: surface, base, subbase, and subgrade from surface deflection measurements. The curves are developed using the Chevron N-layer computer program with a large number of typical combinations of layer thicknesses and material moduli. The load is assumed to be uniformly applied on a single circular plate with a 304.8-mm (12-in.) diameter, a typical condition of the falling weight deflectometer and the road rater with a single circular plate. Twenty-four sets of curves are developed representing a wide range of layer thicknesses and deflection basin shapes. Therefore, if the layer thicknesses are known and the surface deflection measurements are determined, the four moduli of the pavement layers can be evaluated. The developed curves are simple to use without the need for previous empirical relationships or computer analysis. The curves developed here are based on static analysis.