Abstract
Backcalculation of FWD data often results in unrealistic moduli.
The modulus of the subgrade may be two to three times the expected
value, and the modulus of an intermediate granular material may be
lower than the subgrade modulus. If stresses or strains measured
in the pavement are compared with theoretical values, the
agreement is often poor.All theoretical models for calculating
pavement response are based on a number of simplifications with
respect to reality and must be verified experimentally. Most
models assume that all pavement layers consist of linear elastic
materials. This paper demonstrates, that treating the subgrade as
a nonlinear elastic material, can result in more realistic moduli
and a much better agreement between measured and calculated
stresses and strains.The response of nonlinear elastic materials
can be calculated using the Finite Element Method (FEM). A much
simpler approach is to use the Method of Equivalent Thicknesses
(MET), modified for a nonlinear subgrade. The paper includes an
example where moduli backcalculated using FEM, linear elastic
theory and MET are compared. Stresses and strains predicted by the
three methods are also compared to measured values. For this
example it is found that the best agreement between measured and
calculated stresses and strains is obtained with MET. FEM results
in stresses and strains within the range of measured values,
whereas all stresses and strains calculated with the linear
elastic theory are outside of the range of measured stresses and
strains.
Original language | English |
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Title of host publication | Nondestructive Testing of Pavements and Backcalculation of Moduli, Third Volume |
Place of Publication | West Conshohocken, PA |
Publisher | American Society for Testing and Materials |
Publication date | 2000 |
Pages | 14-22 |
Publication status | Published - 2000 |
Event | Nondestructive Testing of Pavements and Backcalculation of
Moduli - Seattle, Washington Duration: 1 Jan 1999 → … |
Conference
Conference | Nondestructive Testing of Pavements and Backcalculation of Moduli |
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City | Seattle, Washington |
Period | 01/01/1999 → … |