The anti-shakedown effect
ByP.R. Donovan & E. Tutumluer
Pages 6

Shakedown in unbound granular layers is well documented; application of additional loads along a channelized path causes unbound layers to densify, gain strength with time, and stabilize with little additional residual deformation. Full-scale airport pavement test data from the Federal Aviation Administration’s (FAA’s) National Airport Pavement Testing Facility (NAPTF) in the US used new generation aircraft loads on asphalt pavements and indicated that a sequential wander pattern caused residual deformations to be recovered, potentially reducing or even negating the shakedown effect. What has been seen is that the downward residual deformation (rutting) caused by a pass of heavily loaded landing gear is canceled by the upward residual deformation resulting from the pass of the same gear offset by wander. This interaction indicates a shuffling or rearrangement of the particles in the unbound aggregate base/subbase layers of the pavement system. The particle rearrangement in turn reduces the strength of the unbound layer causing future load applications to cause more residual deformation, the “anti-shakedown” effect.