Present methods of determining the resilient parameters (modulus of deformation and Poisson's ratio) of granular materials for use in the analysis of pavement structures subjected to moving wheel loads are based on the results of laboratory repeated-load triaxial tests in which the minor principal stress (chamber pressure) is held constant. However, as a wheel load moves over an element of an actual pavement structure, the element is subjected to both time-dependent lateral and vertical stresses. The purpose of this study was to determine the effects of this nonconstant state of stress on the observed resilient properties of granular materials. Based on the current literature, certain factors thought to affect the resilient properties of granular materials were identified. Among these factors, which were later investigated during the laboratory phase, were density level, type of material, load duration, and number of load repetitions. Nonlinear, finite-element analyses of typical pavement sections were used to establish typical horizontal and vertical stress pulses. The characteristics stress pulses were used to test specimens during the laboratory investigation. It was shown that factors such as load duration, stress sequence, and number of repetitions have negligible effects on the resilient parameters. Nonlinear regression analyses of the laboratory data indicated that the resilient modulus is significantly influenced by the state of stress in the material and may be expressed as a function of the first invariant of the stress tensor. Poisson's ratio may be expressed as a function of the principal stress ratio. The effects of density and material type are small compared with the stress-dependent effects. The resilient modulus determined by the constant-confining-pressure test was found to vary insignificantly from that determined by the variable-confining-pressure test. However, the constant-confining-pressure test data greatly overestimate Poisson's ratio because of the anisotropic nature of the material and the greater volume change that is observed in that type of test.

Media Info

  • Media Type: Print
  • Features: Figures; References; Tables;
  • Pagination: pp 1-13
  • Monograph Title: SOIL MECHANICS
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 00081329
  • Record Type: Publication
  • ISBN: 0309023548
  • Files: TRIS, TRB
  • Created Date: Mar 26 1975 12:00AM