Experimental Study Of Wave Action On Offshore Spar Platform

With the exploration of marine oil and gas resources to the gradual development of deep-sea, various offshore platforms which have the good adaptability to the deep ocean environment have emerged recently. Spar platform, due to its excellent motion performance and lower construction cost, gradually be paid much attention by the ocean engineering scholars. In this thesis, both physical model test and numerical calculation methods are adopt to proceed the systematic investigation of wave force, mooring force and motion response character to provide the necessary scientific research basis for the South China deep-sea oil and gas exploration, and also for the security assessment technology of platform under the catastrophic ocean environment.Under the action of both regular and irregular waves, systematic investigations have been performed, for the wave forces on three kinds of model platforms, The effects of the heave plates, helical strakes and different wave amplitudes on the wave forces are experimentally studied. in general, the wave forces enlarge when the Spar platforms attach the heave plates and helical strakes. First and second order wave forces are analyzed to show the nonlinear features of the horizontal and vertical wave forces of the three models under the regular waves.Considering the complexity of model structures, higher-order BEM are used to calculate the wave forces in regular wave condition. The calculated results are compared with the test results. Transfer function and Fourier transform are used to analyze the wave force spectra, especially the frequency-domain characteristics.In the floating platform tests, motion response characteristics and mooring force are separately taken into account. The effects of the heave plates and helical strakes on the platform motions are mainly discussed. The motion reaponse spectra are further analyzed. In the process of the test, the feature of mooring force changing with variable ka is detailed analyzed, Also is verified the consistency of mooring force and motion response in the time-domain.