Jacket Platforms are the most used offshore platforms and dynamic response of such platforms becomes very important especially for deep waters. Importance of the soil-pile system on the dynamic response of jacket platforms is the subject matter of this study. In this paper, it is intended to make an in-depth study on the soil-pile interaction in the dynamic response of the structure. The results " of a computer analysis based on finite element model coupled with boundary elements (springs) to simulate soil-pile interactions and an experiment with jacket tower-model of height 3.5 m and piles of length 1.9 m with elastic springs are presented. The influence of soil stiffness in the dynamic response has been investigated. The point of virtual fixity at different depths of piles for different soil stiffness are discussed. Differences in natural frequency, mode shapes and maximum deflection for different situations are computed and presented. In addition, important conclusions on the inclusion of soil-pile system on the analysis and the errors that can result by its exclusion are quantified for the use of Engineers. A set of conclusions have been arrived which would be quite useful for the practical design of the Jacket Platform.
The Jacket Platforms are the most used offshore platforms and in the Indian context, all the offshore platforms used in Bombay High are of this type. Considerable amount of effort has been made to study the different aspects of Jacket Platforms and the results have helped to know more about the behaviour of these platforms. When jacket platforms are constructed in deeper waters, the dynamic response analysis of the platforms assumes more importance. The behaviour of the jacket both under static and dynamic loads greatly depends on the pile-soil interaction. Various influences of the pile-soil system are discussed.
