USE OF FABRIC REINFORCED SOIL WALL FOR INTEGRAL ABUTMENT BRIDGE END TREATMENT

The bump at the end of the bridge has long plagued motorists, designers, and maintenance personnel. The bump develops from the differential movements of the approach road and the bridge abutment. This movement produces discomfort to motorists, increased damage to vehicles, traffic hazards, and increased maintenance costs. This damage done by the movement of these systems can literally impair the structural integrity of the bridge in extreme cases. The problem is experienced in all states and is a recurring problem for transportation officials in the state of South Dakota. Previous research has shown that the bump was caused by the development of voids under the bridge approach slabs in integral abutment bridges. Void development was shown to be a direct consequence of the thermal-induced movement of the bridge beam/abutment system. To accommodate this mechanism, the state of South Dakota implemented a new design using a geotextile reinforced soil wall in the abutment backfill to create a gap between the backfill soil and bridge abutment. The objective of this research was to determine if constructing an approach fill to an integral abutment structure with a void between the abutment wall and the fill would alleviate development of voids under the approach slabs to the end of the bridge. Additionally, the research was to investigate alternative design methodologies. The work included the monitoring of three bridges constructed with a gap installed between the abutment and the backfill to document the performance of the newly implemented design. A review of designs used by other states was conducted and alternative backfill materials were studied for use in the model test. Additionally, the feasibility of using an alternative backfill was investigated using the SDDOT model integral abutment system at the Brookings Department of Transportation Maintenance Yard.