The dynamic analysis of fixed deep-water platform

Abstract

The industrial progress is closely related with active using of hydrocarbons more than half of reserves of which lie in rock formations beneath seabed or ocean floor. For oil production at the great depth of immersion oil production fixed platforms are used most often. But using of such technological structures is not limited only to interest of oil and natural gas industry whereas they are important for navigation and military purposes. Offshore fixed platforms are exposed to effects of a high seismicity, wind, waves, strong undercurrents and an impulse impact during the movement of ice fields especially when exploitation in northern seas. The impact of different factors on the value of the period of natural oscillations ofthe offshore fixed deep-water ice-resistant platform with the depth of immersion 120 m that rests on the pile foundation was researched. Two discrete idealized models of the platform were used for the analysis: the first model that was implemented without taking into account the flexibility of the foundation and the second model where the flexibility of the pile foundation and the action of ground foundation were taking into account by the addition of elastic links that simulate the elastic connection between joints. Also, impacts of the connected mass of water media that was modeled in the form of additional distributed joints mass and the impact of the ice field that was modeled by the addition of additional links were investigated. The analysis showsthat values of periods of natural oscillations form increase by 8-20% when the flexibility of the pile foundation was taken into account; increase by 9-100% when the impact of the connected mass of water media was taken into account; decrease by 9-100% when the impact of the ice field and water media were taken into accountthat is significant when analyzing of stress-strain state of members of the structure.