Research On Mechanical Characteristics And Protection Technology Of Offshore Platform Structure Under Explosion And Fire

As a typical mechanical intensive marine equipment,there are a large number of flammable and explosive substances and oil and gas transmission pipelines on the offshore platform,and under the long-term effect of external environment and working load,the mechanical equipment and production facilities are very prone to hydrocarbon leakage.In recent years,the frequency of explosion and fire accidents on offshore platforms has been increasing year by year,and their safety and reliability during the service period has attracted much attention of all fields.Therefore,the research on the mechanical characteristics of the offshore platform under the effect of explosion and fire combined with the typical platform structure,and the research on the new protective structure type of the offshore platform on this basis have important research value and wide application prospects for guiding the design and construction of the offshore platform,controlling the formation and expansion of the major disaster accidents of the marine engineering structure and improving the safety of the personnel and equipment of the offshore platform under the effect of explosion and fire.On the basis of summarizing the current status of domestic and foreign research,this thesis adopts a combination of numerical simulation and theoretical analysis,and considers the strain rate reinforcement and high temperature softening effects to carry out research on the mechanical characteristics and protection technology of marine platform structure under the effect of explosion and fire.Besides,this thesis analyzes the inherent relationship between different explosion sources,fire forms and structural damage of typical offshore platforms,and researches the temperature field distribution law when oil pool fire occurs in the enclosed compartment of an offshore platform,and the dynamic response law of the enclosed compartment and the overall structure of the platform in case of explosion after fire.On the basis of researching the mechanism of anti-blast and fire resistance of platform structure,this thesis carries out the research on the new type of protective structure of the offshore platform.The main work and corresponding conclusions are as follows:(1)Numerical simulation and theoretical research.By studying the propagation process and theoretical equations of the explosion shock wave,simulating the propagation process of the explosion shock wave under different Euler grid sizes to compare and analyze with the empirical values,verifying the reliability of Dytran simulation in the field of transient dynamics,the grid size parameters which are sui Table for the research model of this thesis are obtained.Based on structural thermodynamics and large eddy simulation theory,this thesis studies the feasibility of FDS to simulate dynamic fire fields,determines the control equations and combustion models for numerically simulating oil pool fire processes,and provides the theoretical and technical methodological basis for subsequent studies.(2)Numerical simulation research on fire field of offshore platform.Taking the enclosed cabin of the offshore platform as the research object,the fire dynamics simulation software FDS is used to simulate the fire development process of the bilge oil pool and analysis the change law of the flame development,smoke movement,temperature field and oxygen concentration in the fire field of the enclosed cabin.The influence law,wind speed on the temperature field distribution of the structure,is emphatically researched.(3)Research on the dynamic response of offshore platform structure under the action of explosion and fire.By summarizing the change law of the mechanical properties of the platform structure material under the effects of explosion and fire,the numerical simulation constitutive relationship model is determined.Analyzing the dynamic response characteristics of shock wave propagation,structural damage deformation,impact environment and structural energy absorption of the platform's overall structure and closed cabin under different load forms,this thesis obtains the internal relationship between different explosion sources,fire forms and the damage of typical offshore platform structures.(4)Research on new type of protective structure.Based on the research of anti-explosion and fire protection mechanism of offshore platform structures,this thesis proposes the protection structure types of composite energy absorption type and diversion protection type.Taking the dynamic response characteristics of shock wave propagation,structural damage and deformation,impact environment and structural energy absorption under the effect of explosion and fire as the evaluation criteria,this thesis compares and analyzes the anti-explosion and fire-resistant performance between the new protective structure and traditional structure to 0btain a new protective structure with best fire and anti-explosion performance.