Study On The Deterioration And Mechanical Properties Of Reinforced Concrete Tunnel Lining Under Action Of Corrosion

Reinforced concrete lining structure has become the most widely used lining structure form in tunnel engineering because of its high strength,low cost,convenient construction and many other advantages.However,in the long-term service process,the durability problems of lining structure caused by steel corrosion are constantly prominent,and the structure often has serious deterioration or even failure before reaching its scheduled service life,which has a negative impact on tunnel engineering the long-term driving safety has a significant impact.In this paper,based on the extended finite element method,concrete damage plastic model and multi field coupling analysis and other numerical analysis methods,the deterioration evolution mechanism of reinforced concrete tunnel lining structure under the action of erosion environment is systematically studied from macro and micro scales.The research results provide a certain reference for the durability design of reinforced concrete lining structure in the whole life cycle。The main work and research results are as follows:1.Based on the basic theory of extended finite element,the model of uniform corrosion expansion of steel bars is established.Through the calculation and analysis of the cracking process of concrete cover caused by corrosion expansion of steel bars,the different cracking states of concrete cover from crack initiation to crack propagation are obtained,and the cracking position of the cover is defined.Through the secondary development of the program,the cracking parameters of concrete structure are obtained The change rule of the corrosion development of the steel bar,and the mechanism of the corrosion expansion cracking of the concrete protective layer were explored from the micro level.2.The three-phase micro analysis model of concrete is established based on the method of grid division by using the damage plastic model of concrete.The micro fracture process of concrete protective layer caused by corrosion and expansion is reproduced.The influence rules of different aggregate forms,interface layer strength and protective layer thickness on the occurrence and expansion of concrete protective layer cracks are obtained,and the effect of multiple factors on concrete protective layer is explored failure mode.3.Based on the multi field coupling analysis model,this paper studies the damage of concrete structure caused by corrosion expansion of reinforcement and the damage of bond slip property between reinforcement and concrete caused by the accumulation of corrosion products,and makes a comparative analysis with the existing test data to verify the standard parameters in the numerical calculation model,and establishes the tunnel lining structure model to reveal the lining structure under the influence of chloride corrosion environment The deterioration mechanism of reinforced concrete lining structure is described,and the deterioration rule of reinforced concrete lining structure performance under different corrosion rate is obtained,in order to provide some reference for durability design of reinforced concrete lining structure.