The Numerical Analysis Of The Wave Slamming Effect On Three-dimensional Deepwater Semi-submersible Platform

Nowadays, ocean resources have become the focus of the problems of people attention, because land resources gradually consumed. The technology of deep sea engineering get rapid development, however, the research on the safety of offshore platforms is a key factor in the development of the offshore platforms. In the service period, wave load greatly influences the safety of the structure.Based on the research on semi-submersible offshore platform, the effect of slamming load on the marine platform under wave load is analyzed. Under the basic hypothesis of fluid mechanics, three dimensional numerical wave tank is built to simulate wave environment, combining with the basic equations of wave theory. At the entrance of wave tank, the volume fraction of water and the speed of vertical and horizontal are set. In the momentum equation of damping section, damping is added to eliminate the vibration of the water points. The stable wave condition is obtained.In the stable wave field, plate as a simplified model is established to simulate the slamming load on the bottom of the semi-submersible platform deck under the hypothesis of rigid body. The results coincide well with the experimental results. In different wave factors of 2-stokes wave conditions, the slamming load on different posture tablet is research. The effects of angle, relative plate width and relative wave height to slamming load are analyzed. Under the action of regular waves, the empirical formula on slamming pressure, in different angles (α=-6°―+6°), is obtained in the way of statistical analysis.Combining with numerical solver of wave load on the semi-submersible platform model, on the basis of the rigid assumptions, the numerical solution of the motion equations is obtained by using the fourth order Runge-Kutta method. Based on grid technology, the motion response curve of the model is calculated. Under the same wave environment, the slamming pressure values on the fixed semi-submersible platform and that on the semi-submersible platform considering the motion response are compared to obtain the effects of motion response to slamming pressure on the platform deck and pillars. The numerical method of slamming load on semi-submersible platform is obtained.