Geosynthetic reinforcement of backfill behind integral abutments to mitigate approach slab distresses

Abstract

An approach slab typically has a negligible settlement on one end supported by an integral bridge abutment, but a considerable settlement on the other end underlain by a sleeper slab on the backfill due to factors including seasonal temperature changes and traffic loading. As a result, a differential settlement develops between the two ends of the approach slab, resulting in an abrupt change of the pavement gradient. Furthermore, the concave deformations of the approach slab under traffic loads exacerbate this abrupt gradient change, which creates a hazardous condition for vehicles. Four physical model tests were conducted to investigate the feasibility of using geogrids in the backfill to mitigate these approach slab problems due to simulated seasonal temperature changes and traffic loading. The test results showed that geogrids could significantly reduce the settlements of the backfill away from the abutment, which were mainly caused by traffic loading. Horizontal geogrids increased the backfill surface settlements near the abutment, while wrap-around geogrids significantly reduced these settlements. Longer top geogrid layers with wrap-around facing could further reduce the backfill surface settlements near the abutment.