Jet Grouting for the Re-Support of Pier 11A in San Diego, CA

Pavement failures occurred behind the retaining Wall at Pier 11A (former Navy Pier) in San Diego, California. The pavement failures were caused by a loss of soil directly beneath the pavement. It was presumed that the soil in the retaining wall was leaking through the tongue-and-groove joints between the concrete sheet piles located beneath the retaining wall footing, allowing water in, as well as marine borers that ate away the exposed portions of the timber piles, resulting in loss of timber pile support to the retaining walls. Inspection of the front of the retaining wall below the wharf deck revealed a regular pattern of cracks in the pile cap beams extending from the retaining wall to the pile-supported wharf. Jet grouting was successfully used to re-establish the structural support of the footing to the competent timber piles, and to fill the existing void spaces directly under the pile cap. This paper covers the test section, design, construction, and quality control measures on this challenging project.