Geoforensic Analysis of Agba Bridge Failure, Abakaliki, Ebonyi State

Abstract

A geoforensic analysis of Agba bridge, in Abakaliki, Ebonyi State was carried out using a combination of geotechnical, geophysical and hydrological techniques. The results indicate a highly geotechnically variable, partially weathered meta-sediments as foundation. The weathered profile as confirmed by VES indicated a much thicker weathered soft soil to the south-west.  An initial shallow foundation for the South-West Abutment was thus inadequate, leading subsequently to sliding movement, which displaced the reinforced concrete piers. Hydrological analysis of the Agba river revealed critical flow velocities capable of generating local scour of up to 3.5m deep, that equally threaten stability of shallow pier foundation. Accordingly, bored piles extended to 15m have been recommended for the second half of the bridge to the south-west as a remedial measure to guaranty the stability of the structure.

Keywords: Geoforensic analysis, bridge failure, scour, geo-electrical sounding, geotechnical