A Case Study of Geosynthetic-Reinforced Soil in a Low-Volume Bridge Abutment in Iowa

This paper presents findings from a case study conducted on a low-volume road bridge in Iowa, where geosynthetic-reinforced soil (GRS) was used as fill material in the reconstructed bridge abutments. The original steel bridge supported was on concrete abutments and was replaced with a longer railroad flat car bridge and spread footings founded on the GRS fill. The concrete abutments along with some of the existing fill were left in place to serve as GRS facing, and the soil under the new footing was excavated and replaced with GRS fill. The cost of constructing the bridge was about 60% lower than a conventional concrete bridge deck and abutments. Laboratory tests showed that samples reinforced with geosynthetic layers exhibit higher shear strength and lower permanent strain. When a static load was applied over the foundation with a loaded truck, horizontal stress increase was low along the excavation walls. Analysis indicated that the location of the water table and loading conditions influence the bearing capacity and global stability of the abutment system.