The research was orientated towards the development of analytical procedures for the determination of the elastic stiffnesses of the pavement layers from surface deflections measured "in situ" using the Falling Weight Deflectometer (FWD). In order to select the most adequate options for this purpose, the techniques currently available for interpretation of FWD data and the constitutive relationships proposed for characterizing the resilient response of paving materials were reviewed. The finite element method was taken into consideration, given its capabilities for the analysis of pavement structures where the materials exhibit elastic properties which depend on their level of stresses. A finite element code, FENLAP, was developed and validated. The computer program PADAL, formerly used at Nottingham for the back-calculation of stiffness from FWD deflection bowls, required some improvements, mainly related to the modelling of stress-dependent material behaviour and to the iterative algorithm adopted. Subsequently, this resulted in the implementation of two back-calculation programs, LEAD and FEAD. Like PADAL, LEAD is based on a simple layered elastic approach whilst FEAD makes use of finite elements, which are more accurate but also more time consuming. Field data taken from several FWD surveys carried out on UK sites has served for checking and assessing the new software. Tests were also performed with the Multi-Depth Deflectometer (MDD), another device which measures deflections "in situ". The effects of temperature, loading time and moisture content on the structural condition of in-service pavements were investigated, by examination of the literature and analysis of data collected at different seasons. (A)

  • Corporate Authors:

    Nottingham University, England

    University Park
    Nottingham NG9 3FQ,   England 
  • Authors:
  • Publication Date: 1993


  • English

Media Info

  • Features: References;
  • Pagination: 251 p.
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 00726564
  • Record Type: Publication
  • Source Agency: Transport Research Laboratory
  • Files: ITRD
  • Created Date: Oct 28 1996 12:00AM