Backcalculation of moduli in FWD evaluation of pavements: A solution of global minimum

Z. Q. Yue, Jianhua Yin

Research output: Journal article publicationJournal articleAcademic researchpeer-review

1 Citation (Scopus)


Extensive studies have been done on backcalculation of moduli associated with the Falling Weight Deflectometer (FWD) evaluation of road and airport pavements. A review of the recent international developments in backcalculation of moduli reveals that the backcalculated values of moduli are software and user dependent. This non-unique solution Issue has caused practitioners and pavement designers to lose their confidence in the backcalculated modulus values and become skeptical about the blackcalculation practice This issue is the topic that this paper is intended to address. Based on a current layered elastic pavement theory, the concept of a solution of the global minimum, an orthogonol searching technique and associated computer programs are presented to overcome the non-unique solution issue and to obtain user Independent results in backcalculatian of moduli. Numerical examples are given to clearly illustrate the non-unique solution Issue associated with the most current backcalculation computer programs including those widely used in North America, and to verify that the techniques presented in the paper can solve the nan-unique solution issue. It is concluded that the techniques and associated computer programs presented in the paper can be used to effectively obtain user Independent results in backcalculatian of moduli. As a result, practitioners and pavement designers can gain confidence in the backcalculation practice and use the backcalculated modulus values in pavement evaluation and design without doubts.
Original languageEnglish
Pages (from-to)37-44
Number of pages8
JournalHKIE Transactions Hong Kong Institution of Engineers
Issue number2
Publication statusPublished - 1 Jan 1998


  • Backcalculation
  • Layered Elastic Theory. Unique Solution
  • Moduli
  • NOT
  • Pavement Evaluatian and Design. FWD

ASJC Scopus subject areas

  • General Engineering


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