THE APPLICATION OF SHAKEDOWN APPROACH TO GRANULAR PAVEMENT LAYERS

The concept of shakedown was developed for describing the material and structural response to the repeated application of a cyclic load. This paper applies that concept to describing the behavior of unbound granular materials (UGM) in the repeated load tri-axial permanent strain test. Behavior was categorized into 3 possible shakedown ranges A, B or C. where A is a stable shakedown response and C is incremental collapse while B is intermediate. From this data test stresses near or the boundary of shakedown range A and B were determined to define a shakedown limit line stress boundary in p (mean normal stress) - q (principle stress difference) stress space. The shakedown limit line was applied as a yield criteria in the finite element model of the field trial to predict whether or not shakedown occurs in the UGM for a range of asphalt cover thicknesses. For comparison the lower and upper bound shakedown theorems were also applied to the field trial cross sections.