SYMPOSIA PAPER Published: 01 January 1994

Backcalculation of Pavement Layer Moduli, Thickness and Stiff Layer Depth Using a Modified Newton Method


A modified Newton method for the backcalculation of pavement layer moduli, thicknesses, and stiff layer depth from measured surface deflections is presented. The method is an iterative one and can use any mechanistic analysis program for forward calculations (presently an extended precision CHEVRON program is used for this purpose). This method has been implemented in a new backcalculation program named MICHBACK. Several examples of backcalculation based on theoretical deflection basins generated by the extended precision CHEVRON program are presented, and the effect of errors in input layer thicknesses and stiff layer depth on the backcalculated moduli are studied. Moduli backcalculated by MICHBACK are compared with results obtained by the EVERCALC 3.0 and MODULUS 4.0 programs.

Author Information

Harichandran, RS
Michigan State University, East Lansing, MI
Mahmood, T
Michigan State University, East Lansing, MI
Raab, AR
, Washington, DC
Baladi, GY
Michigan State University, East Lansing, MI
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Developed by Committee: D04
Pages: 68–82
DOI: 10.1520/STP18142S
ISBN-EB: 978-0-8031-5267-0
ISBN-13: 978-0-8031-1865-2