Effect of seabed slope on pile behaviour of fixed offshore platform under lateral forces

Abstract

Fixed offshore platforms supported by pile foundations are required to resist lateral load due to wave and current forces. The response to environmental loads is strongly affected by the soil structure (pile) interaction. The forces exerted by waves are most dominant among the lateral environmental forces which governing the jacket structures design especially the foundation piles. The present investigation is to perform a static wave analysis on a typical fixed offshore platform for extreme environmental conditions, and to study the effects of the combined lateral and vertical loads on pile group foundation. The three dimensional modeling and analysis of the offshore platform are done using finite difference method. The present analysis was done under static condition considering the structural and the environmental loads at extreme environmental conditions, by reaching the state of static equilibrium. A parametric study has been done by varying the seabed slope to examine the variation in soil-structure interaction behaviour of piles. It has been found that the lateral displacement at the pile top and at the seabed level increases as the seabed slope increases. It is also noticed that the depth at which the maximum shear force and bending moment occurs from the pile top increases as the slope of the seabed increases.