Static Capacity of Closed-Ended Pipe Pile Driven in Gravelly Sand

Abstract

This paper presents the results of a static load test (SLT) and two dynamic load tests (DLTs) performed on a closed-ended steel pipe pile (CEP) with an outer diameter B=610 mm (24 in.) driven into a gravelly-sand soil profile. Cone penetration tests (CPTs), standard penetration tests (SPTs), and laboratory tests were performed to fully characterize the soil profile at the test site. The CEP was instrumented with 40 electrical-resistance and 24 vibrating-wire strain gauges. Locked-in residual loads were measured at the end of driving and used to correct the pile capacity components measured during the SLT. Load-settlement curve, load transfer curves, and unit shaft resistance profiles were obtained from the SLT data. Shaft and base resistances obtained from the SLT were compared with estimates from signal-matching analysis of DLT data and CPT-based pile design methods. The signal-matching analysis of the DLT data underpredicted the shaft and base resistance by a factor of two. The CPT-based pile design methods predicted the shaft resistance reasonably well; however, they overpredicted the base resistance by a factor of two. The overestimation by the CPT-based methods can be attributed to the presence of high gravel content near the pile base.