Research On Numerical Modeling And Simulation Of Jacket Platform Under Marine Environment

Oil resource is the pillar of the world’s energy sources supply. With the continuallyincreasing demand of the world for oil, it is difficult to meet the demands simply dependingon land oil resources, which makes the offshore oil industry begin to rise and develop rapidlyin the world. As the main engineering structures in the offshore oil development, the structureperformance of the offshore platform determines the safety and durability of platforms inservice. Having been in the hostile marine environment for a long time, suffering theinfluence from wind, wave, flow, earthquake, etc., the local components and overall structureof the offshore platform reflects a less resistant situation, so do the strength and bearingcapacity. Analyzing the effects of the marine environment load acting on platform structureaccurately and effectively, is of great significance on the offshore platform design, installation,maintenance and so on.The similar model of a jacket platform has been taken as the study object in this paper.The numerical simulation method was applied on the relevant study, which is on the structureperformance and response of platform structure under the effect of wind, wave, current,earthquake, etc. has been conducted with the finite element software ANSYS.（1） Calculating the wind load the platform structure bore by the pseudo-staticmethod, it turns out that the displacement response of the deck is the maximum, so is thestress value of the pile foundation of pipe. It is seen that the response in extreme seaconditions is stronger compared with the results in general situation. It is necessary to analyzethe situation in practical engineering.（2） The fifth order Stokes wave theory is used to describe the motion of wave, andsimulate the wave loading acting on the platform. The static load analysis was carried outunder the condition of maximum coupling force of wave and current. The result shows thatthe maximum displacement response of platform is at the deck of it, and the maximum stressis at the pile foundation of pipe. The transient dynamic analysis of the platform under thewave and current loading shows that the platform appears periodic reciprocating motion,whose period is familiar with the wave period, the displacement response values of differentposition are different, from mud line to platform deck, the value increases gradually, theplatform deck structure deformation, maximum stress appears in the leg pile position.（3） As two kinds of seismic wave, EL Centro and Tianjin wave, were selected as anincentive, transient dynamic analysis of the platform structure was carried out, the seismicresponse form of the platform is closely related to the incentive form of seismic wave. Theresponse of the platform structure in the direction of the acceleration input is stronger than that from other directions. As3D EL Centro wave was selected as an incentive, transientdynamic analysis was carried out on the platform structure, the response of the platform in ahorizontal direction is obvious, while the response in the vertical direction is very small,which shows that horizontal earthquake can be a make a bigger impact on platform structure;the response of the platform structure can be easier inspired by3D seismic compared withthat of1D seismic; As for the response of the platform structure on the seismic wave, themaximal displacement response is located at the deck, while the maximum stress is in the pilefoundation of pipe.