Evaluation of the Critical Responses of Flexible Pavement Structure with Stabilized Sabkha Base and Geogrid Reinforcement

Abstract

Marginal and problematic soils such as dune sand and sabkha cover wide areas in the eastern, southern, and western parts of the Kingdom of Saudi Arabia in addition to the coastal line of the Arabian Gulf. The most common problems of these problematic soils are high compressibility, low shear strength, large volume change (especially in sabkha), and low bearing capacity. Therefore, this research reported a series of finite elements modeled by the Plaxis 3D software to evaluate the critical responses of pavement structures constructed using these marginal soils. The pavement structure consisted of a standard asphalt concrete layer, a base layer of sabkha soil treated with Emulsified Sulfur Asphalt (ESA), and a sand subbase layer. These layers were resting on the natural sabkha subgrade. The model’s input parameters for each layer were a combination of laboratory and literature data.  The simulation was done for a pavement section without reinforcement and another reinforced with geogrid positioned at different places to study the best location reducing critical responses, i.e., fatigue, rutting strains, and damage ratio. The hardening soil model was selected to model the nonlinear behavior of an ESA–sabkha base, sand subbase layer, and sabkha subgrade while the linear elastic model was used for asphaltic concrete layer and geogrid material. The simulation outcomes displayed that positioning geogrid reinforcement at the interface of an ESA–sabkha base and sand subbase layers led to the maximum decrease in horizontal tensile (fatigue strains) and vertical compressive strains (rutting strains) and vertical displacement. Furthermore, geogrid reinforcement decreased the fatigue damage ratio significantly (31 to 51%), while the reduction in rutting damage ratio was a little bit lower (11 to 25%). Finally, placing geogrid on the subgrade leads to a higher reduction in fatigue and rutting strains and vertical displacement.