Retrofit of a Pile-Supported Bridge in Soft Clay Damaged by Failure of Adjacent Soil Stockpile

The Roger Pierlet Overpass, built in 1975, was displaced and damaged in November 2004 by foundation soil movement caused by failure of a large soil stockpile placed adjacent to the bridge. The concrete bridge is supported on long precast concrete piles driven through soft marine clay to toe bearing in very dense till-like soils. The soil failure caused cracks in pier columns and pile cap beams, displaced structural elements, and significantly damaged the precast concrete piles. Shortly after the damage was discovered, temporary support towers were erected to provide support for the bridge decks and to allow traffic to safely continue on the bridge. Permanent retrofit of the bridge included strengthening of columns and beam/column joints, extension of existing pile caps, and addition of steel pipe piles to replace the damaged concrete piles. This paper presents details of the damage, subsequent ground investigations, and the temporary and permanent retrofits of the bridge and its foundations.

Sy, A., T. Thavaraj, B. Hamersley and D. Gillespie. 2011. “Retrofit of a Pile-Supported Bridge in Soft Clay Damaged by Failure of adjacent Soil Stockpile,” in: 64th Canadian Geotechnical Conference, 14th Pan-American Conference on Soil Mechanics and Geotechnical Engineering, and 5th Pan-American Conference on Teaching and Learning of Geotechnical Engineering, Toronto, Ontario, October 2-6, 2011. Toronto: Canadian Geotechnical Society.

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