| Generally speaking,most of the researches on the stability of semi-submersible platforms only consider the influence of wind tilting moment without considering the impact of waves on the stability of the platform.However,the waves encountered by the semi-submersible platform during towing will also It generates a large overturning moment on the platform and affects the stability of the platform.Therefore,this paper simulates the wave action of the platform during ocean towing in the frequency domain,and considers the effect of the wave action on the stability of the semi-submersible platform.In order to study the effect of waves on the stability of the platform,the stability of the platform without considering the effects of waves is first examined to provide a reference for the subsequent analysis and comparison.To this end,the Moses software was used to establish a numerical model of half the submersible platform,and its hydrostatic and tank capacity data were calculated to ensure the accuracy of the numerical model.After that,based on the requirements of the relevant platform stability specifications,3 draughts,24 wind direction angles,and 2 wind speeds were selected for the complete stability of the platform for a total of 96 calculation conditions,and the complete stability of the platform was calculated and analyzed;For the stability of the platform,8 types of cabins were selected,3 draughts,24 wind directions,and a total of 480 calculation conditions.The platform’s stability of the cabins was calculated and analyzed.The calculation results show that Under this kind of calculation conditions,the stability of the target platform is excellent,and the stability of the integrity and the breakdown of the cabin meets the stability standards required by the code.After obtaining the stability characteristics of the platform under the action of waves,the frequency domain calculation is performed on the platform,and a total of37 wave directions are spaced at 5 ° intervals within the wave direction range of 0 °-180 °.The maximum inclination of the platform and the maximum bending moment of the wave to the platform.Finally,two analysis methods are proposed,considering the influence of the maximum inclination angle and the maximum bending moment,respectively.First,the effect of waves on the stability of the platform is characterized by the parameter of maximum inclination,that is,when the maximum inclination is added in the conventional stability analysis,the results show that the stability of the platform only decreases to a small extent,and the stability of the platform is the smallest.The area ratio decreased by 6.76%,and the maximum inclination angle of broken cabin stability increased by 8.72%,indicating that this analysis method may not consider wave effects sufficiently,and the platform still has stability risks.Second,the effect of waves on platform stability is the largest.This parameter is used to characterize the bending moment.In the conventional stability analysis,this maximum bending moment is added to calculate 37 wave direction angles and 24 wind direction angles for a total of 888 calculation conditions.The results show that the platform is complete and stable.Both the stability and the breaking stability are greatly reduced.Under the most dangerous environmental conditions,the minimum area ratio of complete stability is reduced from 3.16 to 0.04,the weathertight inlet is lower than the waterline,and the tilt angle range included in the restoration torque curve is 14.71 °decreased to 6.38 °,which no longer meets the requirements of the specification.Since this analysis method essentially considers the maximum moment of wave inclination as a static moment,the influence of wave load on stability may be considered too much,which is a safe method.Therefore,the accuracy of this research method needs further experimental verification. |
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