Shakedown analysis of anisotropic asphalt concrete pavements with clay subgrade

Abstract

The essence of a shakedown analysis is to determine the critical shakedown load for a given pavement. Pavements operating above this load are predicted to exhibit increased accumulation of plastic strains under long-term repeated loading conditions that eventually lead to incremental collapse (e.g., deep ruts). Those pavements operating at loads below this critical level may exhibit some initial distress, but will eventually settle down to a steady state in which no further mechanical deterioration occurs. Conventional pavement design procedures assume that the pavement deteriorates indefinitely. However, there is now ample field evidence that this is not always true and that steady-state conditions are frequently achieved. The materials in the various layers of the pavement are modeled as elastic-plastic Mohr-Coulomb materials. Anisotropic strength effects are studied as well as the influences of variable temperature, stiffness, strength, and thickness of the asphalt concrete layer. A lower bound approach is used to provide safe estimates of the critical shakedown load.Key words: shakedown theory, multilayered pavements, anisotropy.