The anti-shakedown effect

Repetitive loading along a channelized path causes unbound aggregate layers to densify, shakedown, and stabilize with little additional permanent or residual deformation per each wheel pass. Full-scale pavement tests conducted at the Federal Aviation Administration's National Airport Pavement Testing Facility (NAPTF) in the US indicated that a sequential aircraft wheel/gear wander pattern causes residual deformations to be recovered in the unbound aggregate layers. The downward residual deformation 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 shuffling or rearrangement of the particles in the unbound layer, which in turn reduces the strength of the layer causing future load applications to cause more residual deformation, the "anti-shakedown" effect. This paper analyzes the anti-shakedown effect of the contractive/dilative response of the unbound layers using multi-depth deflectometer data from NAPTF testing.