Study On Similarity Relation Of Chloride Erosion Effect Of Pre-stressed Concrete Members Under Underwater Zone In Marine Environment

The pre-stressed concrete structure is widely used in marine concrete structure with the advantages of good structural performance and high economic efficiency.However,the durability of structural members under the long-term soaking of seawater and the damage of marine environment is becoming more and more prominent.Due to the large amount of energy consumption and the durability of large engineering,the construction of pre-stressed concrete structure has seriously restricted the sustainable development of our country and has been paid more and more attention by the engineering industry.Supported by the National Natural Science Fund Project "Research on theory and engineering application of similar marine pre-stressed concrete structure durability(51278230)",in order to solve the problem of the chloride salt erosion effect of the pre-stressed concrete members under the marine environment,this paper based on the similarity of the effect of chloride salt erosion in concrete carry out experimental research,the effect of accelerated corrosion experiment on the corrosion resistance of the test-piece and the site structure is discussed,the similar relationship between the corrosion effect of indoor simulation accelerated experiment test-piece and explored structure component.The main research contents are as follows:1.Complete the service structure of the site test,design and complete the indoor simulation accelerated test.Durability inspection and environmental investigation of 69 th berth in Xugou Port of Lianyungang.According to the results of the survey and the investigation,the erosion system of the indoor simulation experiment is designed based on erosion effect similar,the indoor simulation acceleration experiment is designed and the erosion of the indoor experiment is experimented.The results show that the indoor experiment is highly similar to the field experiment.2.The environmental-stress-time similarity model under the coupling of environment and stress was constructed by analyzing the experimental data.The results of field experiments and laboratory experiments were analyzed separately,it shows that the chloride ion concentration-time curve gradually increases and tends to be gentle.The larger the water-cement ratio is,the larger the chloride ion concentration is,the larger the diffusion coefficient of chloride ions is.The chloride ion concentration and the diffusion coefficient of chloride ions decreases with the increase of compressive stress level.Based on the similarity theory,the environment-stress-time similarity model under the coupling of environment and stress is deduced by the Fick's second law diffusion model.The correlation coefficient is corrected according to the experimental data.3.Experimental study on behavior of prestressed concrete beams subjected to chloride ion attack.According to the engineering structure and environmental conditions of the design of prestressed concrete beams and indoor simulation accelerated erosion experiment,after a certain period of time to carry out the normal section bearing capacity experiment.The results showed that the prestressed beams were subjected to erosion and concrete curing in the soaking solution,and the concrete strength The strength of C40 experiment beam erosion effect is significant,the bearing capacity is significantly reduced,the concrete strength grade C50 experiment beam in the solution by the water conservation role compared to the solution erosion is more obvious,its bearing capacity has even increased.4.Verify the environment-stress-time similarity model,and propose the model application method.For the berth of the service structure 60 th berth in Xugou Port of Lianyungang,based on the similarity theory,produce an indoor simulation accelerating experiment member similar to the actual structure.The durability of the engineering structure is simulated by periodically detecting the erosion of the test-piece.Accoding to indoor simulation accelerated experiment and field experiment results,the similarity coefficient ?_t=10.95 of time and the similarity coefficient ?_x=2.49 of the chloride ion erosion depth were calculated.