Study On The Influence Of Seawater Fluctuation On The Transport Law Of Chloride Ion In Concrete

On the basis of reviewing the existing literature results,this paper comprehensively uses physical model tests,numerical simulations and theoretical methods to study the law and characteristics of chloride ion transport in concrete under seawater fluctuations.The main work and conclusions are as follows:(1)Based on the self-developed marine environment simulation device,the generation system of simulated ocean waves is established,and the simulated ocean waves with different working conditions are formed.The time-frequency distribution characteristics of the simulated multifield flow velocity are tested and analyzed,which is the premise of known flow velocity.The analysis of concrete chloride ion transmission law and identification of its performance parameters were carried out,which laid the foundation for the experiment.(2)Based on the Fluent turbulence model,the simulated flow field is numerically simulated,and the time-varying information of the flow velocity distribution of the experimental flow field is improved.The positive relationship between the flow velocity and the pressure is obtained,and the chloride ion transport of the concrete is accelerated for the analysis of seawater fluctuation.Provide the basis.(3)The spatio-temporal variation characteristics of chloride ion transport in the splash zone and underwater zone of marine concrete components were studied experimentally.The results show that under the same rotating condition of the wave simulation device,the chloride ion in the underwater area is transported faster than the splash zone,although the latter has a larger flow rate.(4)The chloride ion transport law under different flow rates and hydrostatic immersion was studied,and the experimental evidence for the acceleration of chloride ion transport in the concrete wave was obtained.The results show that in the concrete with the same water level,the chloride ion transport increases with the increase of the flow rate,and the dynamic water is significantly larger than the chloride ion concentration under the hydrostatic condition.(5)Based on Fick's second law,the parameters of chloride ion concentration and diffusion coefficient of concrete surface under wave condition were fitted and identified.Compared with the experimental results,high precision fitting goodness was obtained.The velocity influence function is introduced and the surface chloride ion concentration model and diffusion coefficient model considering the seawater flow rate and time-varying factors are established.(6)Using the MATLAB output aggregate random model,the chloride ion transmission model considering the factors of time,flow rate,temperature and humidity was established by COMSOL software,and the rules were discussed based on the model,and then the parameter sensitivity analysis was carried out.The results show that with the increase of time,the chloride ion content increases,but the growth rate gradually decreases,and the growth rate of the concrete column is greater than the medial growth rate;the hydrostatic penetration and the hydrodynamic penetration show significant difference,and the flow rate increases with time.The increase in the penetration between the moving water and the still water will further increase.