A case history is presented to better understand the effect of grain shape on pile capacity in sand. Results are presented for 20-in.-square precast prestressed concrete piles driven with a Delmag D46-23 single acting diesel hammer in Escambia Bay, Pensacola, Florida. Soil conditions consisted of very soft to soft clay to a depth of 40 ft, underlain by medium dense to dense fine to medium sand to a depth of 78 ft, and dense to very dense silty fine sand. The driving of 18 indicator piles was monitored using a Pile Driving Analyzer. The Case method was used to estimate the pile capacity. CAPWAP analyses were also performed for 11 piles. Static load tests were performed on four piles. The piles drove harder than expected but the load tests indicated lower capacities than expected. The sands did not have high carbonate content, cementation, or high mica content. The angular to subangular shape of the sand grains was the only unusual feature. Large rebounds were observed during the installation of the indicator piles. The CAPWAP analyses also indicated that the sands have soil quake and damping values generally larger than expected.
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