Shakedown Analysis of Road Pavements - Application to Project Level and Network Level Scenarios

P S Ravindra

doi:10.4038/engineer.v43i4.6998

Abstract

Shakedown behaviour of road pavements was investigated in laboratory controlled conditions using the Sydney University Pavement Testing Facility. Wheel loads lower than the shakedown load generated low permanent deformations for a larger number of load cycles in comparison with high permanent deformations for a lower number of load cycles for wheel loads higher than the shakedown load. Computer software was developed to calculate the shakedown limit using elastic stress distributions calculated with Sydney University's FLEA (Finite Layer Elastic Analysis) program. Case studies of shakedown theory to solve project level construction issues and remaining service life calculations at the network level are presented.

Highlights

A typical pavement structure is usually designed for a 40 year design period and to carry more than 100 million standard axles during its service life in modern day pavement design standards
6.1 Database Data acquired was comprised of subsurface pavement settlement data from LVDTs, the time of reading, the lateral location of the wheel, number of test cycles, spring load monitoring data, subsurface permanent deformation details and transducer calibration data
Results indicate that larger deformations occur for fewer load cycles when the wheel load is more than the shakedown load

Summary

Introduction

A typical pavement structure is usually designed for a 40 year design period and to carry more than 100 million standard axles during its service life in modern day pavement design standards. Some major arterials in the developing world are designed to carry more than 400 million standard axles to a shorter 20 year design period Most of these heavily trafficked roads are increasingly funded by private sector investors on behalf of local Road Authorities and so the road owners are very keen to utilise the pavement materials to their maximum strength capacity. Griining [3] and Bleich [2] proved the static shakedown theorem for a system of steel beams with "I" shaped cross sections They pointed out that for the case where repeated loads acting upon a given structure vary over a wide range, a structure can fail due to low-cycle fatigue below the collapse load calculated from a mechanism of instantaneous collapse and an accumulation of plastic deformation may occur making the structure unserviceable. The failure criterion was MohrCoulomb and material properties were assumed to be linear elastic - perfectly plastic

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Results

Conclusion