Evaluation of Compressive Bearing Capacity of Long Offshore Steel Piles Driven in the Persian Gulf

Abstract

Long driven steel piles are widely used in the foundation of fixed offshore oil and gas extraction platforms. There are different methods to determine the pile bearing capacity, including static analysis, using the results of in-situ tests, as well as static and dynamic pile loading tests. In recent years, the in-situ cone penetration test has considerably been developed in the design of offshore piles owing to its high accuracy, continuous recoding across the depth, and similarity to pile. In this paper, for the first time, a comprehensive data bank, including soil engineering parameters derived from laboratory and in-situ tests as well as field measurements obtained from dynamic pile tests in short, medium, and long term conditions, is developed for the Persian Gulf - South Pars field. Afterward, fourteen methods including four offshore static analysis methods and ten direct methods based on cone penetration test results are selected and applied to estimate the axial compressive bearing capacity of steel pipe piles driven in the studied area. According to the findings of the conducted statistical analyses, the lowest precision and prediction quality are provided in the four static analysis methods compared to the CPT-based methods for the developed data bank. The values of ultimate pile bearing capacity obtained from the static analysis methods are on average 70%, 63%, and 35% higher than the corresponding values measured by the dynamic pile tests, in short, medium, and long term conditions, respectively.