Reinforcement Mechanism And Device Research On Grouted Clamp For Local Flaws Of Offshore Jacket

Marine platform offshore jacket is widely used in offshore oil development and subsea drilling.Different forms of damage occur in offshore platform due to the long-term severe marine environment.So the study of reinforcement technology has vital significance.In order to effectively solve the local damage problem of offshore jacket,a simple and effective reinforcement method for grouted clamp is adopted with the advantages of large tolerance and high anti-skid strength.As a marine engineering repair technology,the grouted clamp has been widely applied abroad.However,few researches for the reinforcement mechanism of grouted clamp are carried out,especially for its design method.The serialization and standardization are still on the exploration stage.Therefore,it is necessary to further study on the strengthening mechanism and design method of grouted clamp.The theory calculation,finite element simulation and mechanical experiment are adopted in this paper considering the reinforcement mechanism,flaw hinging design method and the experimental prototype of grouted clamp,specific research work of the dissertation is presented as follows.The pre-stress distribution of the grouted clamp is studied,and the variation rules of radial pressure and circumferential pressure along the wall thickness of grouted clamp connector are obtained by the numerical analysis.Moreover,the load-bearing mechanism of the rigid-flexible-rigid body of grouted clamp connector under cyclic displacement load is simulated based on the finite element method.The elastic modulus of grouted clamp connector loaded by three-direction axial pressure is formulated.The load-bearing capacity is obtained by the buckling analysis.Then the design method of grouted clamp aiming to flaw position is proposed.And the main designing steps of grouted clamp are researched.According to the principle of flaw hinging design method,the grouted clamp under working loads of offshore platform is analyzed.Based on the reinforcement mechanism and design method of grouted clamp,the main structure of grouted clamp with different joint types is designed.Importantly,the structure of straight pipe grouted clamp is investigated around the opening and closing structure,locking structure and sealing structure.Then the simulation analysis of the rectangular seal under preload and working pressure is carried out and the working principle of the packing seal is illustrated as well.The suitable cement type is selected according to its grouting characteristics.And the optimum proportion experiment of cement slurry is performed.A mechanical experimental platform is established to measure the stress variation with strain gauges.A series of experimental researches on straight pipe,K-pipe and X-pipe under the axial compression are performed out.Then the stress of the pipe-joint after reinforcement is compared with the stress before reinforcement.What's more,the reinforcement reasons of the protection parts of grouted clamp are elaborated.On that basis,the effect of grouted clamp on the repairing pipe joints is discussed,which verified the reliability and feasibility of grouted clamp as a repairing method for local damaged jackets.