In recent years the analysis of pavement structures has relied increasingly on characterizing material properties (such as resilientmodulus) by use of nondestructive deflection testing and backcalculation procedures. An important element common to all backcalculationprocedures--the technique used to achieve a "convergence" of the measured and calculated deflection basins--will be described. A convergence method based on the use of nonlinear least squares is described. The method was adapted to a layered elastic program (chevron n-layer). This convergence approach improves moduli estimates over priorprocedures; however, the most important element is the ability to efficiently backcalculate not only layer moduli but also layer thicknesses. This ability is illustrated by using hypothetical two- and three-layer pavement sections and by using real data for a three-layersection. This paper appears in transportation research record no. 1293, Backcalculation of pavement moduli 1991 .
Samenvatting