Erosion Mitigation of Bridge Abutment Backfill during Flood Events

Abstract

The erosion of the structural backfill behind bridge abutments subjected to water flow conditions representative of extreme and overtopping floods was examined through scaled water tank testing using physical hydraulic models. The erosion behavior of the unreinforced backfill materials, embankment material, and structural backfill was tested. Based on the observed patterns of erosion and embankment failure of these tests, the proposed construction practices, including geosynthetics and riprap, were examined in the laboratory with the objective of reducing erosion and the probability of failure during flood events. The input flow rate, flow velocity, and upstream and downstream waterheads were controlled and measured during the tests. The research results indicated that slope failure before overtopping can be mitigated by using a riprap on the slope. Geosynthetics, including geogrids and geotextiles, effectively prevented global failure during flood events if the reinforced core of the backfill was appropriately wrapped.