Indicator Pile Program at Port o Oakland, California-Paper

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The Berth 22 replacement at the Port of Oakland required about 570 precast concrete piles, some up to 164 feet long. An indicator-pile program using dynamic testing (PDA) and CAPWAP analyses led to substantially longer recommended piles than the original design, particularly in Rows D–G. The program was expanded to 38 test piles, 25 restrikes, and 41 CAPWAP analyses.<br /><br />Testing revealed that the crushed-rock fill provided much less pile skin friction than expected; a 25-degree friction angle is tentatively recommended for capacity calculations. The underlying San Antonio Formation was highly variable, with alternating dense sand, silt, and occasional clay. For most of this formation, the report recommends using a 35-degree friction angle for skin friction and 25 degrees for end bearing with the FHWA method. In roughly half the project area, a very dense layer near elevations -47 to -50 feet could cause refusal. For piles bearing in this layer, an end-bearing factor, Nq, of 60 is recommended.<br /><br />Jetting through the San Antonio Formation did not show a clear reduction in skin friction, so the 35-degree recommendation remains applicable. The longer piles in Rows A–C extended into high-plasticity clays, where capacity increased significantly with time as excess pore pressures dissipated and soil strength recovered. Row A piles initially fell short of required capacity at one-week restrike, but met requirements after two to three weeks. The report therefore recommends at least two weeks of setup for these long piles.<br /><br />Overall, the findings emphasize the importance of accounting for rockfill behavior, subsurface variability, and time-dependent capacity gains, and support using a sufficiently broad indicator-pile program to guide final pile lengths and installation criteria.

Keywords

Berth 22

Port of Oakland

precast concrete piles

dynamic testing

PDA

CAPWAP

pile skin friction

San Antonio Formation

setup time

end-bearing factor