ABSTRACT
Flooding is recognized as a catastrophic event and a threat to the load carrying capacity of pavement structures around the world. During a flood event, the moisture content within the pavement layers can increase significantly, resulting in reduced bearing capacity of the pavement system. Road agencies must decide to what extent traffic should be restricted to avoid the potential damage that could be caused if the capacity of the pavement structure is exceeded in the flooded condition. This study presents a methodology to evaluate the structural capacity of flooded pavements to provide an engineering basis for application of short-term load restrictions during and post flood events. Conventional Terzaghi’s bearing capacity formulation and the concept of effective stress in unsaturated soils were used; apparent cohesion was introduced to account for the suction in unsaturated soils. Bearing capacity under traffic loading was calculated by changing the soil condition from unsaturated to the fully saturated flooded condition. The flooded condition was simulated by raising the water table from an initial hydrostatic capillary pressure distribution for different cross sections with a range of subgrade soils. A significant reduction was observed in bearing capacity mainly when the pavement structure was in the fully saturated condition, but the road could regain its capacity with desaturation and recession of water level. Finally, layer elastic analysis was performed to predict the maximum tire withstand without any sudden shear failure.
