Shakedown analysis for design of flexible pavements under moving loads

Abstract

In this paper, a numerical method based on shakedown theory has been developed to calculate shakedown load limits of flexible pavements under moving surface loads. The shakedown results can serve as a design basis for flexible road pavements for the prevention of excessive plastic deformation. This numerical method utilises elastic stress fields obtained from finite element analyses and calculates optimum shakedown multiplier for each pavement layer by means of a self-equilibrated critical residual stress field. Finally, the shakedown load limit of a flexible pavement is found as the minimum shakedown multiplier among all layers. The results of numerical analyses examine the effect of surface frictional coefficient, material properties and layer thicknesses on the shakedown load limits, and meanwhile provide an insight into the differences between two-dimensional and three-dimensional pavement models. A simple design procedure using the shakedown method is also developed for layered, flexible road pavements.

Keywords:

• shakedown
• flexible pavements
• plastic deformation
• moving loads

Acknowledgements

The work reported in this paper forms part of an on-going research programme at the Nottingham Centre for Geomechanics (NCG) on shakedown theory and its application to the design of pavement and railway foundations. The first author would like to thank the China Scholarship Council (CSC) for funding her PhD study. The authors also wish to thank the Engineering and Physical Sciences Research Council (EPSRC) and the University of Nottingham for financially supporting the research programme.