Sheetpile Bulkhead Failure Investigation in Savannah, Georgia-Paper

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On June 18, 2022, the sheet pile bulkhead at Savannah’s Hutchinson Island ferry landing began moving, opening a large crack in the brick plaza. Over the following two weeks, the wall deflected about nine feet at the top, and the ground behind it settled approximately seven feet. Emergency bracing and temporary pipe piles prevented the bulkhead from collapsing into the Savannah River.<br /><br />The investigation found that soft clay had been left beneath the fill during original construction. As this clay settled, it likely imposed additional loads on the bulkhead’s helical anchors and tie rods. About half the tie rods broke and half pulled out; surface corrosion was not severe enough to be a primary cause. The eastern section moved more than the western section, consistent with the thicker layer of trapped clay there. Analysis of the extracted sheet piles and computer modeling indicated that the anchors failed first, followed by excessive bending of the sheets. The failure was not attributed to global instability. A small nearby earthquake may have hastened failure but was considered too weak to be the main cause.<br /><br />The replacement bulkhead was built 16 feet riverward of the original, using 65-foot sheet piles and a pile-supported concrete deadman instead of individual helical anchors. Oversized tie rods were placed in PVC sleeves to accommodate ground settlement. A pile-supported relieving platform for the plaza, steps, and planters was added to reduce lateral pressure on the wall, along with improved drainage.<br /><br />The investigation’s findings informed the repair and highlight the importance of accounting for residual soft soils, settlement-induced anchor loads, and low-tide conditions in bulkhead design.

Keywords

sheet pile bulkhead

Savannah Hutchinson Island

bulkhead failure

soft clay settlement

helical anchors

tie rods

Savannah River

emergency bracing

replacement bulkhead

drainage improvement