A Case Study: Soil Setup for Piles Driven into Eastern Coastal Plain Deposits in Virginia-PPT Presentation

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This case study examines time-dependent soil setup—the increase in pile resistance after driving—for bridges along Interstate 64 in Virginia’s Coastal Plain. The study covered two project areas with varied sedimentary formations and driven H-piles and precast prestressed concrete (PPC) piles. Dynamic load tests measured resistance at end of initial drive (EOD) and during later restrikes.<br /><br />Initial EOD capacities were often small and unreliable, so resistance gains were assessed using later restrike measurements. Setup varied with pile type, soil conditions, and elapsed time. Reported setup factors generally ranged from about 1.5 to 4, though individual results varied more widely. Both fine- and coarse-grained materials showed meaningful setup.<br /><br />The study applied the Skov and Denver method to estimate setup using an A-parameter, with initial resistance referenced at two hours after driving. Average A-values were 0.4 for H-piles and 0.8 for PPC piles. The resulting estimates suggest PPC piles generally gained resistance more rapidly and substantially. About 70–75% of the resistance gain during the first 30 days was estimated to occur within the first two weeks. Setup continued beyond 30 days, but at a decreasing rate.<br /><br />The model’s accuracy varied: errors increased with measured pile capacity, and applying the A-parameter equally to shaft and toe resistance sometimes produced total resistance estimates 100–200 kips above measured values. The study also found no clear direct relationship between CPT sleeve resistance and estimated unit shaft resistance.<br /><br />Overall, pile setup depends on soil type, pore-pressure dissipation, pile type, and time after driving. Additional dynamic testing and improved shaft-resistance estimates could refine the empirical A-parameter approach.

Keywords

pile setup

time-dependent resistance

bridge foundations

dynamic load tests

Interstate 64

Coastal Plain soils

H-piles

precast prestressed concrete piles

Skov and Denver method

pore-pressure dissipation