Investigating the axial stiffness of large diameter piles in non-cohesive soil

As a new generation of converters of up to 8 MW have already been developed, there is a demand for large diameter monopiles to serve as support structures for wind turbines. Under such circumstances, a favourable design which ensures sufficient safety with the least possible cost seems to be crucial. This paper presents a review of the offshore design guidance in accordance with American Petroleum Institute (API RP-2A) design standard, since it is the most widely used method in the offshore foundation design engineering. However, concerning that the API design methods are almost based on empiricism and are conducted on pile diameters range 0.2 to 2 m, it is questionable that the current API recommended practice would still be considered as an efficient method for the foundation designs based on large diameter piles. Therefore, test results obtained from two scaled monopile models are presented to show the behaviour of vertical loads on piles in non-cohesive soil. Additionally, a two-dimensional numerical model using Finite Element Method is developed and the bearing capacities of the piles are obtained to find out a correlation between the results.

Keywords:

Offshore , monopile , finite element method , vertical load , Plaxis 2D