Premature refusal of large-diameter, deep-penetration piles on an offshore platform

• Set up the relationship between soil resistance to driving (SRD) and ratio of set per blow to energy (S/E).
• Parameter study of an empirical relationship to estimate the time effect on the resistance.
• Evaluate the API method by comparing the results of API with that from CAPWAP and GRLWEAP.

Open-ended pipe piles are commonly driven into the seabed to support offshore platforms. This paper presents a case of practical offshore driven pile installation experiences associating with premature refusal. Pile drivability and capacity are analyzed using sufficient driving records. Dynamic loading tests were performed three months after the driving in order to determine the pile capacity after refusal. The test results are detailed in this paper compared with back analysis of measured pile driving records. Empirical equations are provided to predict soil resistance during driving and after setup according to the driving records and dynamic loading tests. Analyzing this practical engineering case is hoped to lead to a better understanding of pile driving, especially when premature refusal occurs. The sufficient details of the engineering data in this paper are also expected to enrich the engineering experience and literature of offshore piles in offshore engineering.