Numerical Simulation And Durability Research Of Shield Segment Under Chloride Attack Condition With Cracks

However, at the same time, the rapid development of the subway also increasingly exposed many problems, gradually began to study the problem of durability of subway structural. The paper relies on the issues "Underground structural performance and environmental coupling mechanism " of the National Key Basic Research and Development Program (973:2011CB013802). For shield tunnel segment with cracks in concrete structures under load coupled chloride ion penetration and expand the role of the durability research. The main contents are as follows:(1)Under chloride-based coupling of erosion and load the completed segment performance tests (artificial environment test) data acquisition parameters are derived chloride ion concentration, the diffusion coefficient of the tube sheet erosion of chloride ions in concrete structures under variable expression;(2)According to derived parameters, chloride ion penetration of concrete segment model was established,basing on the establishment of Comsol Multiphysics software, to the erosion of time, the erosion of chloride concentration factor for the trial to test the numerical study of chloride ion erosion mechanisms, explore the erosion of time and concentration of chloride attack influence of chloride ion diffusion inside the concrete, and the results of numerical experiments with artificial environment test results were analyzed;(3) A further ananysis to the reason of concrete crack appearing and representative parameters can build a numerical experimental model with considering chloride ion erosion mechanisms of crack.Width and deepth of the crack as the experimental factor discuss the influence the crack to the chloride ion erosion,to make a further analysis the influence range of the crack and the erosion effect to the chloride ion,and build a chloride ion erosion model with crack considered.(4)Through theoretical analysis to determine the load calculation expression crack pipe sheet structure, combined with consideration of crack model coupled chloride ion penetration cracks under erosion environment, load segment durability to evaluate model.