Research Of The Sea Ice Load On Polar Wide Structure

The abundant oil and gas resources in the Arctic region make it a hot spot for energy development in the world.However,due to the high latitude and perennial cold conditions in the arctic region,high requirements are placed on engineering technology for the safe and clean mining of oil and gas resources.The development of ice mechanics in China is relatively late,and China is located outside the Arctic Circle,which lacks the experience of offshore extreme cold engineering.The research in depth on polar ice load can master the core technology of cold regions to realize the independent development of polar resources.By summarizing the sea ice environment conditions of the Barents Sea and Kara Sea,the range of general glacial period,level ice thickness and ice speed in the Arctic sea area are given.Based on existing norms and data from field surveys conducted by Arctic scientific expeditions,the rule of sea ice growth and melt in the Arctic region,sea ice salinity,density and ice temperature range in the Arctic region are clarified.The uniaxial compression test and flexural test of the natural sea ice in the Bohai Sea and Yellow Sea have been carried out.It is found that the uniaxial compression strength of sea ice has obvious size effect in the ductile-brittle transition zone.Based on Timco's sea ice strength calculation formula,the modified multifactor function of sea ice compression strength and flexural strength in a wide range of applications is obtained.The numerical simulation of the interaction process between ice and wide structure is carried out by discrete element method.The correctness of the simulation of sea ice dynamics process by discrete element is verified by the experimental data of the Bohai caisson platform and the Arctic offshore platform.The failure mode of interaction between sea ice and wide vertical structure is analyzed.It is found that the sea ice with a thickness of more than 0.2m is dominated by compressive failure,the ice speed is higher than 0.05m/s,and the compressive failure and mixed failure are dominant.As the structural width increases,the sea ice changes from compressive failure to mixed failure,and the non-contemporaneity of compressive failure becomes more prominent.The extreme static ice force formulas given by the norms and researchers are compared and analyzed.Based on the discrete element analysis,the effects of ice speed,ice thickness,structure width and other factors on ice load are discussed in detail,and the segmentation calculation model of wide structure extreme static ice force is obtained.The characteristics of the accumulation behavior of broken ice before the wide structure are analyzed.It is found that the ice tends to be discharged downward after crushing,and it is more likely to accumulate below the water surface.The height and width of the crushed ice accumulation area increase with the interaction time of ice and structure.The discrete element numerical simulation of the local ice load of the wide structure is carried out,and compared with the field measured data provided by the ISO specification.The results show that the discrete element numerical method can simulate the local ice load change better during the interaction between sea ice and structure.Non-simultaneous failure of ice occurs on the whole of the wide structure,and local simultaneous failure occurs in the local area of the contact surface to form a high pressure area.The distribution of the extreme values of the local ice pressure in space and time is random.The local ice pressure at the center of the ice sheet is large and the edge pressure is low.The study found that the local ice pressure is not only related to the area,but also related to the relative ice thickness position of the local area.After introducing the dimensionless parameter analysis of h/w_L,the formula for calculating local ice pressure related to ice thickness and ice area is obtained.The research results of this paper show that in the absence of field monitoring and laboratory tests,discrete element numerical method can be used to study the local ice load,which can provide certain theoretical basis for the anti-ice design and safety guarantee of the wide structure in the cold region.