Study On The Impact Of Boundary Condition On Life Design Model And Its Impact On Service Life Of Marine Concrete Structure

The surface free chloride ion content is an important parameter describes the boundary conditions of chloride ion diffusion equation concrete,which is important for marine concrete structure analysis and quantitative design.Thus,we need to use a large number of exposure station,indoor natural diffusion test and the actual project of long-term data,analysis the change of surface free chloride content of marine concrete structures,can set up in line with the actual situation of the chloride ion diffusion equation with boundary conditions,consequently to accurately predict the life.In this paper,through the engineering verification test,field exposure test and life analysis examples,combined with the actual engineering exposure station and long-term data collected a large number of domestic and foreign research,the time variation of the surface free chloride ion content in concrete structure and its effect on life.At the same time,a large amount of data accumulation of more than red established by Professor Yu V1.0 correction ChaDuraLife chloride diffusion model and life analysis software and the research group for many years,the sea crossing engineering design and analysis of the life,and to provide a basis for the ChaDuraLifeV1.0 database of the most basic life analysis software.The main work and conclusion of this paper are as follows:?1?According to the field exposure test results of Dalian and Qinhuangdao exposure stations,it is found that there has a certain correlation between surface free chloride content(C_sf)and total chloride content?Cst?.We further summarize the 942 sets of C_sf and C_st paired data from the research group,the exposure station and the actual project at home and abroad,and find that there is a universal linear correlation between Csf value and Cst value.?2?By consulting concerned literatures,focuses on 58 exposure station and 69 projects,combined with the linear correlation between C_sf value and C_st value,we collected 2030 sets of measured data of22 international maritime exposure stations and actual projects,including 581 groups of Chinese data,including 345 sets of data of our research group.The use of foreign exposure time of 1449 groups of test data of 0.5⁹7a,the research of marine concrete structures in the C_sf value variation,while the use of the domestic and the exposure time of our research group for 581 sets of experimental data to verify the 0.2⁸2a,confirmed that the C_sf value is a power function or exponential function,very good with the exposure time,the power function relationship more in line with the actual situation of concrete service life,Based on the above data,we studied the relationship between Csf value and water binder ratio.It is found that there is a significant correlation between Csf content and water binder ratio of marine concrete mixed with slag.?3?The Csf value of four exposed areas of the marine concrete structure in the atmosphere,splash zone,tidal zone and underwater zone showed a time variant with the increase of exposure time,and then tended to be stable.Through a large amount of data collection at home and abroad,the time-varying equation of the median and upper and lower values of the C_sf value of the marine concrete structure in four regions is determined.Using ChaDuraLife life analysis software research found that the model uses different C_sf time-varying boundary conditions with different C_sf degeneration,and combined with the different decay characteristics of different boundary conditions and the diffusion coefficient of chloride ions,the selectivity of the reliability analysis of the life stage,the two stage or three stage diffusion model,calculation of concrete structure in service exists different life results showed that C_sf content of time variation and selection of different chloride ion diffusion model in the service life of extreme importance in the design of marine concrete structures.At the same time,it is proved that there are some problems in the values of C_sf parameter in the European DuraCrete model.?4?In Dalian,Southern China and South Korea representative sea crossing engineering as the research background,using ChaDuraLife life analysis software to calculate and analyze the life of marine concrete structures,and calculation model,and the European Duracrete us Life-365 model to analyze the results,confirmed the ChaDuraLife V1.0 model and software boundary conditions and chloride ion the diffusion coefficient of double time-varying,very suitable for marine concrete structure service life design.?5?Using the ChaDuraLife life analysis software,the life calculation of the typical subsea tunnel projects at home and abroad were carried out.The results show that the design conditions,design requirements of ChaDuraLife to calculate the life can reach 100a or 120a,and the C_sf upper and lower values in the ChaDuraLife model,even if the construction quality problem unfavorable,resulting in the value of C_sf is controlled improperly,can still limit changes with the C_sf value of tracking the re inspection and analysis,operation and maintenance measures when necessary.