PERFORMANCE OF PRECAST DRIVEN PILES IN MARINE CLAY

Abstract

The research reported is concerned with the behavior of precast reinforced concrete piles driven through soft marine clay and founded in residual soil and weathered rock of sedimentary origin; to study the load-transfer behavior of such piles, strain gages installed along the pile shafts were monitored frequently during the static loading tests and at regular intervals during and after the construction of the superstructure. Piezometers were installed in proximity to one of the piles. The dissipation of excess pore water pressures indicated that setup in the marine clay was highly significant. Hence, pile capacities calculated using wave-equation models based on stress-wave measurements during initial pile driving gave consistently lower values than those of static loading tests one week later. Long-term instrument readings indicated development of negative skin friction when the piles were in service. The downdrag increased with time, and this additional loading should be accounted for in the pile design as part of the service load on the pile. © ASCE.