Accelerated fatigue damage of a rigid pavement overlying a sub-surface void: a computational analysis

The structural analysis procedures used in rigid pavement design assume the slab-base interface to be perfectly planar and no imperfections in the sub-surface soil exist. This assumption of course would be violated if severe erosion were to occur due to inadequate drainage, thermal movements, and/or mechanical loading. To date, the effect of erosion is only considered in the faulting performance module, but not in the structural analysis procedure. In the fatigue analysis, soil erosion is not considered entirely. In this paper, the bottom up fatigue cracking potential caused by the combined effects of wheel loading and a localized imperfection in the form of a void below the mid-slab edge is studied. The pavement was modeled using Abaqus. More than 1100 runs were executed to study the interactive effects of non-dimensional slab length, thickness, void geometry, base stiffness, linear temperature gradient, and load configuration. Both bonded and un-bonded slabs were considered. The results indicate that the stress amplification and fatigue cracking potential increase as the non-dimensional slab length increases and slab thickness decreases. The effects are more severe in a bonded pavement system. In addition, under certain conditions, the thermally induced stresses mitigate stress amplification caused by mechanical loading.