| In order to further promote the rapid development of regional economy, the Hong Kong-Zhuhai-Macau Bridge's construction is carried out. Sea-crossing immersed tunnel is at high temperature and humidity in the marine environment, with the characteristics of chloride by serious, service life of high demand, poor maintenance and high maintenance costs. Immersed tunnel cube is a massive concrete structure of complex section. It is highly demanding in the early crack control. How to ensure the durability of concrete structure and crack resistance, to ensure the immersed tube tunnel in the design of the base period is not less maintenance and repair is very important. Therefore, the thematic research for the immersed tube tunnel durability and crack resistance is necessary and urgent.This article on the basis of comprehensive exposition the durability factors of immersed tube tunnel of the South China Sea,Against the principle of chloride ions of the marine environment erosion the the concrete than led to the cracking of steel corrosion and cause the damage of structure durability,applied to the preparation and test of the high durability and high cracking resistance concrete of immersed tube tunnel,studied the issues of parametric analysis and crack control technology of hydration heat temperature stress and massive concrete structures with complex cross,established the the research methodology and theoretical framework of the durability and crack resistance of the important structural of immersed tube tunnel.The work and innovation of the paper carried out mainly:1) According to the marine environment of south China, through qualitative analysis of influencing factors and damage mechanism of structure durability and the prediction model of durability lifetime are carried out,this paper proposes that the main factors affecting concrete structure durability is high-temperature and high-humidity and high chlorine ion concentration of Marine environment, and reviews the effect of high-temperature and high-humidity environment to structure durability.2) This paper summarizes design principle and method of high permanent stability and high crack resistance concrete, and determines the design ideas of double mixing fly ash and slag and decreasing hydration heat and chloride permeability coefficient.According to these, prepare high permanent stability and high crack resistance concrete using on immersed tunnel, through the common mechanical test and chloride permeability test and the hydration heat test, the optimize the optimum proportion of concrete is determined.3) In order to systematically analyze the pre-stress problems early section of immersed tunnel tube, complex cross-section of early stress in mass concrete finite element analysis model is established. This paper carries out the hydration heat temperature stress analysis In MIDAS platform and deeply investigates the effect of various parameters on the temperature cracks of concrete hydration heat by adjusting the parameters of the materials, construction and maintenance to find the optimal overall scheme, and determines the key technical indexes meeting the requirements for crack control, such as materials, construction and maintenance.4) For the influencing factors of early cracks and preventive measures, the systemic analysis is carried out. This paper proposes comprehensive crack control measures, such as using high permanent stability and high crack resistance concrete, reducing molding temperature, and so on. Combining with the early stress analysis, this paper proposes the key protective apparatus for crack control thoughts and actions.Finite element analysis software programming ideas of mass concrete temperature stress and the various simulation analysis and simulation analysis techniques involved in various time-varying parameters of concrete of the simulation method are also discussed. |
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