Bearing Capacity Analysis of Offshore Piles in the Persian Gulf using CPT Results and Time Effect Consideration

Steel pipe piles are used as the foundation of marine structures such as bridges, hydrocarbon extraction platforms, wind turbines and anchoring elements. Due to the importance and high construction cost of these structures, any weakness and failure in their pile foundations can lead to catastrophic economic, environmental and social damages. Therefore, accurate analysis, safe design and reliable determination of their bearing capacities are of particular importance. In this study, the compressive axial bearing capacity of 24 long offshore driven steel pipe piles in the cohesive sediments of the Persian Gulf is estimated using 10 methods based on direct results of cone penetration test (CPT and CPTu) and 5 methods based on static analysis. The bearing capacity values obtained from these methods are compared and validated with the corresponding measured data attianed from the pile dynamic analysis tests. Then, the performance of these methods are analyzed in terms of accuracy and quality of predicting shaft, tip and total bearing capacities based on 12 statistical criteria. Subsequently, the probable time of soil set-up around the offshore piles in the Persian Gulf is estimated using laboratory and field tests as well as the emprical relationships available in the technical literature. It is shown that the piles installed in the considered area will have the highest growth of bearing capacity after about 100 days from the initial driving and reach their maximum or long-term bearing capacities.