Analysis of Vertical Bearing Capacity of Single-Row Pile Group of an Offshore Platform

Abstract

The vertical bearing capacity of a special pile group of platform in an offshore gas field has been studied. Large diameter d (2.134 m), deep penetration l (96 m), small spacing sa (3.507 m), and only one row piles are the usual characteristics of the pile group foundation in offshore engineering. According to the requirements of the related design code, the super pile group effect has to be considered. However, with the usual design code, when sa/d, the ratio of spacing to diameter, is less than 2.0, there is no way to consider the pile group effect. In this paper, considering the occlusion effect of soil plug of pipe pile, several methods have been introduced to study the super pile group effect of the vertical bearing capacity. These methods include linear elastic theory method, the method recommended by the Code of Pile Foundation in Port Engineering (JTJ254-98), and the method with virtue of the existing pile group model test results. Meanwhile, the plugged and unplugged conditions have been considered, respectively. Through the analysis, the factors of safety in extreme and normal operation states are obtained, and the results satisfy the design specifications.

Study on Load-bearing Characteristics of Different Types of Pile Group Foundations for an Offshore Wind Turbine

“…The loading transfer mechanism of piles was summarized that load sharing behavior of piles and soil were comparatively studied through the comparison of the model test results of single pile foundation, single pile foundation with cap and vertical pile group foundation with different space length (Zhang et al, 2005). The vertical bearing capacity of a special pile group of platform in an offshore gas field without the consideration of pile group effect was studied with several methods, including the method of linear elastic theory recommended by the Code of Pile Foundation in Port Engineering (JTJ254-98), and the method based on the existing results of pile group model test (Zhuo et al, 2012). Numerical analysis methods involving finite element method (FEM) were widely used to understand the bearing capacity behavior of piles and then numerical methods were established (Ribeiro and Paiva, 2014;Zhan, Wang, and Liu, 2012).…”