Dynamic Response Analysis And Reliability Study Of Deepwater Jacket Platform Structure

With the development of offshore oil and gas resources,China's offshore oil and gas industry is also stepping up efforts to the development of deeper waters where more abundant oil and gas resources.For the deepwater jacket platform,its dynamic response is particularly significant under the action of wind,wave,current and other marine environments,and the structure will be fatigued by the action of general sea conditions for a long time in the service process,which impact on production activities and staff safety.Therefore,it is necessary to study the dynamic response and reliability of the deepwater jacket platform.This work not only ensures the safety of the platform,but also has important significance for the design,construction and maintenance of the deepwater jacket platform.In this paper,the deepwater jacket platform is taken as the research object.The static analysis and dynamic analysis of the structure of the deepwater jacket platform under extreme sea conditions are carried out by using SACS,and the reliability of the deepwater jacket platform is studied by using S-N curve method according to the statistical characteristics of ocean waves.The main content is as follows:(1)Wave theory and its applicability.The paper derived the parameters of wave particle velocity potential in linear and nonlinear wave theory and their applicability in different water depths.And analyzed the nonlinear mechanical analysis of pile-soil is carried out,and the influence of pile group effect on the platform force.(2)Structural static analysis of deep water jacket platform.The paper established the 3-D mechanical model of deepwater jacket platform,and analyzed the force and displacement of the platform structure under the sea conditions with a recurrence period of one year and one hundred years,which obtained the UC value and stress distribution of each member of the platform.What's more.the paper used pushover method to analysis was carried out on the jacket platform,which analyzed the process of collapse,the extreme sea condition 0°,45°,90°three wave direction and the reserve strength coefficient of 8 degree earthquake under the action of the platform and base shear.(3)Dynamic response analysis of structures of deepwater jacket platforms.The modal analysis of the deepwater jacket platform was carried out,which based on the Guyan reduction method.And the dynamic response of the pile-soil-structure model and the equivalent pile model of the deepwater jacket platform was analyzed by applying the modal superposition principle and applying deterministic wave parameters,and then,the dynamic response of a platform subjected to random waves is simulated by generating pseudo-random waves using the ocean simulation method.and the dynamic response of the platform subjected to 1000s random wave loading is simulated by pseudo-random wave generation with ocean simulation method.(4)·Structural reliability of deepwater jacket platforms.Generated in the Marine environment on the platform on the basis of the statistical characteristics of random stress,based on the s-n curve and Miner rule using wave spectrum analysis platform some important tube node to estimate the fatigue life were carried out,and USES the Wirsching fatigue reliability model reliability was studied for the deep water jacket platform pipe node,it is concluded that the node fatigue life than design life,the reliability index averages of 3.2,conform to the requirements of the API specification.