Growth-rate-dependent prediction of pile set-up and its application in driven pile foundation construction

ABSTRACT

In this paper research was presented on the development of a growth-rate-dependent model for pile set-up prediction using the restrike and static/statnamic load testing data collected from different projects. The data included: a) restrike records from ninety-five production piles and restrike and load test results of nine instrumented piles driven in soft clays from the relocation project of Highway No. 1 in Louisiana (LA-1); and b) restrike and static load testing data of five fully instrumented square PPC piles driven at four different bridge sites in various soil layers from sands to clays in Florida. Research effort was focused on the prediction of the ultimate shaft resistances with pile set-up formulated using the pile resistance growth rate-dependent model. The timeframe of interest was studied for a practical set-up magnitude such as 90% of the ultimate shaft resistance (Q₉₀). As an application of the rate-dependent model, it was found that piles at the LA-1 relocation project, in general, reached about 95% of the ultimate shaft resistances at the time of 2 weeks after pile installation. The strategy of incorporation of pile set-up in adjusting pile driving criteria or/and design during pile construction, such as the experience-based plan of a two-week waiting period adopted by Louisiana DOTD, was investigated and justified.

KEYWORDS:

• pile set-up
• growth-rate-dependent model
• ultimate shaft resistance
• timeframe to achieve design pile resistance

Acknowledgments

A portion of the research work presented herein was performed as part of Louisiana Transportation Research Center (LTRC) contract No. 04-1GT. The support and assistance of the LTRC office and LADOTD personnel, specifically from Drs. Doc Zhang and Ching Tsai, are gratefully acknowledged.

Disclosure statement

No potential conflict of interest was reported by the author.