Vibro Concrete Columns Solve Problems for Victory Bridge Approach Fill

The Victory Bridge replacement project in Perth Amboy, NJ involves a new high-level structure, the southern approach embankment to which will be supported on Vibro Concrete Columns (VCC) installed through existing fills over loose sands and organic deposits. Three major design issues with the approach fills and associated retaining walls were: large expected total and differential settlements due to organic soil consolidation; seismically-induced large settlements and slope failures anticipated due to liquefaction of the loose saturated sands during the design earthquake; and a tight construction schedule. Based on the evaluation of long-term performance, cost and schedule impacts, a design was chosen that included rigid support of the embankment fill using VCCs in conjunction with a reinforced soil-high strength geosynthetic base mat. The rigid concrete columns bear on the deep dense sand. The economic design enables a high level of performance during a seismic event, reduces differential settlements between the pile-supported abutment and roadway, eliminated the need for piles to support a retaining wall, and can readily be accomplished within the project schedule and site constraints. Construction is underway and will be reported upon in detail in a future paper, however this paper contains design considerations and general construction information.