| Nowadays,as an important infrastructure for the exploitation of marine oil and gas resources,ultra-deepwater drilling platforms have long lived in harsh marine environments.Apart from working loads and environmental loads,accidental accidents such as explosions caused by oil and gas leaks may occur on drilling platforms.If an accident causes some important structural damage on the platform,this will not only lead to property damage,environmental pollution,equipment damage or even the safety of the staff.Therefore,it is of great practical significance to study and evaluate the dynamic response and structural performance of the structures under the accidental explosion load.It has important reference value for platform quantitative risk assessment,offshore optimization safety design and sustainable and healthy development.This paper establishes a numerical model suitable for the drilling platform of this paper by analyzing the basic theories under the explosion accident,including normative analysis,nonlinear dynamic finite element analysis and structural simplification analysis based on single degree of freedom system.In this paper,the general analysis of the dynamic response of the blasting performance of the upper hull structures under the explosion accident and the structural simplification analysis based on the single degree of freedom simulation are studied.In addition,the results of the corresponding numerical simulations are used as a reference,and the simplified analysis results under the explosive load are compared and verified.This paper provides a reference for predicting the structural anti-explosion performance and improving the structural performance of the hull on ultra-deepwater drilling platforms under explosive accidents.The specific research content of this paper is as follows:(1)The research mainly summarizes the requirements of the current foreign relevant regulations,the main research status of structural damage analysis under the explosion accident and the basic theory of the research.Combined with the sea area situation of the target platform and its structural form,the research determines the explosion accident scene applicable to the target platform,the explosive load form,the load size and its calculation condition,and selects the moon pool structure of the drilling area as the target research site.(2)The numerical simulation of the explosion shock wave flow field and its grid size effect are studied.The numerical analysis software is used to simulate the characteristics of the shock wave flow field after explosion and its propagation trend.This paper compares the simulation results of overpressure peaks with the results of theoretical empirical formulas from the grid size effect.Finally,the suitable size of the grid for the target platform under explosion accident scenario is concluded.Based on the requirements of the specification,the relevant parameters of the explosion scene were determined,and the finite element modeling of the hull structure on the ultra-deepwater drilling platform was completed.(3)The nonlinear finite element method is applied to study the structural response performance of the rig structure under the action of explosive load.The explosion scenarios of the upper hull structure under different load sizes and different explosion source locations are simulated.The dynamic response,structural damage and energy changes of the structure under blast loading are compared and analyzed.The study found that the upper-hull structure has excellent anti-explosion performance,and the energy absorption and transmission of the structures are balanced.In the explosion scene of 43.3m height position,the internal structures of the moon-pool are the most impacted,and the bulkheads of the exploding surface present sag deformation.The damage of the intermediate deck and the inner wall of the moon-pool along the X direction is the most serious.(4)This paper studies the application of simplified structural analysis of drilling platforms under explosive loads.Simplified analysis and application methods for different structures,loads and resistances in an explosion scene are collated and summarized.The simplified analysis method of the equivalent single degree of freedom system was used to analyze the structural damage of the two inner walls of the drilling platform moon pool structure which were dangerous in the explosion accident simulation.The research finds that the simplified analysis method is in good agreement with the numerical simulation,and the error is within 15%,which meets the requirements of engineering practice.It can be used to quickly predict the anti-explosive capacity of the structures and the damage deformation modes under the explosive load.However,more research is needed on the application of complex structures.The research work in this paper can lay a foundation for the further study of the structural anti-explosion performance of the drilling platform under the explosion accident,and can provide some valuable reference for the structural optimization design and structural explosion-proof design of the marine structure. |
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