Prediction of Potential Cracking Failure Modes in Three-Dimensional Airfield Rigid Pavements with Existing Cracks and Flaws

This paper predicts the potential for crack propagation in concrete pavements under aircraft loading given a starter fatigue crack at the bottom of the concrete slab or a surface-initiated shrinkage crack on top of the slab. The generalized finite element method was used to evaluate the stress intensity factors for quarter elliptical cracks placed at the critical top and bottom tensile stress locations. The pavement was loaded with a single triple-dualtandem (TDT) gear and two TDTs accounting for the entire belly gears. When the pavement was loaded with the two TDT gear configuration, the analyses showed significantly higher K_I (shear mode) values for surface-initiated cracks than for bottom-initiated cracks for the same crack size. Therefore, concrete slabs with preexisting surface cracks are more likely to exhibit top-down crack growth despite being designed for bottom-up fatigue cracking under certain loading conditions. The theoretical framework allows for improved assessment of the fracture susceptibility of concrete slabs under aircraft loading, specifically the potential for top-down over bottom-up cracking.