Study On Horizontal Bearing Characteristics Of CFRP Composite Piles In Marine Environment

Fiber reinforced polymer(FRP)has the advantages of light weight,high strength,good corrosion resistance and easy construction.It was widely used in the reinforcement of concrete structures.However,research on the durability of such structures in corrosive environments was not sufficient.With the rapid development of China's economy,the scale of infrastructure construction in coastal areas has been increasing.It was necessary to consider the influence of Marine environment on the durability of building pile foundation to ensure the safe use of the structure.CFRP composite piles use CFRP bars instead of steel bars in ordinary reinforced concrete piles,and wrap one or more layers of CFRP cloth around the pile.This paper uses the indoor model test,combined with theory and ABAQUS finite element software analysis.The variation of bearing characteristics of CFRP composite piles under different corrosive time in marine environment was discussed.The research content of this paper mainly includes:(1)The seawater concentration of 5 times was selected for durability test,and it was called artificial seawater as a manually arranged seawater corrosion solution.In order to speed up the testing process,this paper simulates the durability of CFRP composite piles in the Marine environment through indoor model tests.In this paper,laboratory model tests are conducted to simulate CFRP composite piles under different corrosion ages in marine environment.Finally,the variation law of horizontal bearing capacity was obtained.;(2)In this paper,CFRP bars and CFRP cloth were placed in the prepared artificial seawater,and tensile tests were conducted on 0d,30 d,90d and 180 d after corrosion respectively to study the variation of tensile strength of CFRP bars and CFRP cloth in the Marine environment.The test results show that the tensile strength of CFRP bars and CFRP cloth decreases by 5.33% and 6.64% respectively after 180 days of corrosion in artificial seawater.They show good corrosion resistance;(3)According to the Winkler foundation model,the horizontal bearing capacity of the pile foundation needs to consider the bending stiffness of the pile and the resistance of the foundation soil.In this paper,the ZT-FY30 self-balancing reaction frame is used to study the variation of bending stiffness of CFRP composite piles and reinforced concrete piles under different corrosion times.The test results show that with the increase of corrosion time,the bending stiffness of reinforced concrete pile decreases more than that of CFRP composite pile;(4)The large-scale model tank and self-made loading system in the laboratory were used to obtain the variation of horizontal bearing capacity of CFRP composite piles and reinforced concrete piles under different corrosion times.The test results show that with the increase of corrosion time,the horizontal bearing capacity of reinforced concrete piles decreases significantly compared with CFRP composite piles;(5)The composite resin matrix moisture absorption rate compound Fick's second law.In this paper,the moisture absorption rate of CFRP cloth in seawater with different corrosion time was measured.Finally,the diffusion rate D of seawater into the interior of the CFRP cloth was calculated.The Mass Diffusion module in ABAQUS finite element software was used to simulate the diffusion of chloride ions into the interior of CFRP cloth.The simulation results show that the CFRP cloth was attached to the surface of the structure,which can significantly reduce the diffusion process of chloride ions in the seawater and prolong the service life of the structure.