Analysis On Ultimate Bearing Capacity Of Fixed Platforms Under Super Typhoon

Typhoon is one kind of the strongest natural catastrophes, which has threatened the petroleum operation security severely in South China Sea especially to the jacket fixed platform. Platforms suffer various degree damage from the super typhoon and are even destroyed. Jacket platform is one of foundational equipments in offshore oil exploitation with huge volume, complex structure and high daily cost. Therefore, in order to guarantee operation security and economy of platform, it's very important to simulate the wind load of each modules accurately and analyse the ultimate bearing capacity of platform under typhoon.Firstly, 3D numerical simulation of wind field around platform in different wind directions was analyzed on the basis of CFD method. Stress and velocity in wind field, wind load of platform and modules were simulated. Secondly, Considering the nonlinear coupling interaciton between seabead soil and pile, the finite model of platform was established and structural static analysis was processed by the use of ANSYS software, so that the maximum equivalent stress and displacement in 100 return period environment load were calculated and the most dangerous point was selected. Furthermore, the transient analysis was also processed considering the dynamic response of wave load, and the displacement, velocity and acceleration response graphics were simulated, then the maximum response value were compared to the results of static analysis. Finally, Based on the ANSYS and static pushover analysis, a new method on ultimate bearing capacity analysis was presented aiming at the jacket platform suffering from the wind, wave and current load at the same time. Besides, models of platform considering bend components, lost components, erosion, marine growth attachment and pile foundation scouring were established and analyzed separately. And then, the influence to the ultimate bearing capacity of each type of platform was researched by comparing the reserve strength factor between the defective and intact platform. The research achievement of this paper can supply theoretical basis for design of structural stress, layout planning, structural strength check, ultimate bearing capacity analysis and security assessment.