Innovative Drilled Shaft Installation Process Through Existing Bridge FoundationsÂ-Video

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A Houston bridge expansion near Galveston Bay encountered the buried foundations of a demolished 1950s drawbridge. The old pile caps, seal slabs, steel, and hollow precast piles obstructed construction on the east side, where the bridge had already been built up to the channel. The team replaced each planned pile group with a single 2-meter-diameter drilled shaft, installed from barges in deep water. Because each shaft had to meet a demanding one-inch placement tolerance, they first cored a larger hole through the old concrete foundation, then used a powerful rotator to set permanent casing accurately and drill out the embedded concrete, steel, and piles. The shafts were completed with slurry, reinforcing cages, and concrete. All four were installed successfully within tolerance. Sonar also showed the old foundations were about five feet deeper than expected; regional land subsidence, driven by historical groundwater pumping, likely explained the difference.

Keywords

Houston bridge expansion

Galveston Bay

buried bridge foundations

drilled shafts

land subsidence