内养护高强混凝土渡槽温控仿真研究

发布时间：2018-09-18 17:49

【摘要】：渡槽作为跨越溪谷、河渠、道路和洼地的交叉渠系建筑物,广泛应用于区域调水、引水灌溉等工程。在现代大型渡槽建设中,大量采用了高强混凝土槽身结构。高强混凝土由于水泥用量高、水胶比低,混凝土温度收缩和自收缩大,为调控高强混凝土早龄期自干燥和自收缩现象,防止及控制裂缝的产生和发展,“内养护”的概念应运而生。本文通过试验、理论分析和数值模拟的手段,结合前人的研究成果,对内养护高强混凝土特性,温度、应力仿真计算方法以及防裂方法等问题进行了研究,主要工作和结论如下:(1)基于前人研究成果,采用混凝土水管冷却温度、应力场基本理论,实现了水管冷却效应的温度和应力仿真计算。(2)采用页岩陶粒+粘土陶粒等量替换粗骨料的内养护方法,设计高强混凝土绝热温升试验方案,进行绝热温升计算模型。经对比分析知:复合指数模型结果和实测结果相关性最好,可用于温控设计和仿真分析。(3)对渡槽混凝土受外界影响或自身特性因素导致的各种变形进行分析讨论,指出温度变形和干缩变形是渡槽混凝土裂缝产生的主要原因之一。(4)结合实际工程,采用三维有限元数值模拟的手段,验证了(3)的结论,研究了内养护方式、通水冷却、表面保温等防裂措施的防裂效果,结果表明:通水冷却和内养护+表面保温的措施均可大大降低混凝土开裂的可能性,但通水冷却易产生“管壁裂缝”问题;通过经济性分析,确定了经济合理的渡槽混凝土防裂措施,为后续类似工程温控防裂提供参考。
[Abstract]:Aqueducts are widely used in regional water transfer, diversion irrigation and other projects, as cross canal structures across streams, canals, roads and depressions. In modern large-scale aqueduct construction, a large number of high-strength concrete tank structure. High strength concrete has high cement content, low water-binder ratio, and high temperature shrinkage and self-shrinkage of concrete. In order to control the phenomenon of self-drying and self-shrinkage of high-strength concrete at early age, the occurrence and development of cracks can be prevented and controlled. The concept of "internal conservation" came into being. In this paper, by means of experiment, theoretical analysis and numerical simulation, the characteristics of internally cured high strength concrete, temperature, stress simulation calculation method and crack prevention method are studied in combination with the previous research results. The main work and conclusions are as follows: (1) based on the previous research results, the basic theory of cooling temperature and stress field of concrete pipe is adopted. The temperature and stress simulation calculation of cooling effect of water pipe is realized. (2) the internal curing method of replacing coarse aggregate with shale ceramsite is adopted to design the test scheme of adiabatic temperature rise of high strength concrete and carry out the adiabatic temperature rise calculation model. The results of comparison and analysis show that the composite index model has the best correlation with the measured results and can be used in temperature control design and simulation analysis. (3) the deformation of aqueduct concrete caused by external influence or its own characteristics is analyzed and discussed. It is pointed out that temperature deformation and dry shrinkage deformation are one of the main causes of concrete cracks in aqueduct. (4) combined with practical engineering, the conclusion of (3) is verified by means of three-dimensional finite element numerical simulation. The anti-cracking effect of anti-cracking measures, such as surface heat preservation and so on, is shown. The results show that the measures of water cooling and internal curing surface insulation can greatly reduce the possibility of cracking of concrete, but water cooling is apt to cause "pipe wall crack", and through economic analysis, The concrete crack prevention measures of aqueduct are determined, which provides a reference for temperature control and crack prevention of similar projects.
【学位授予单位】：华北水利水电大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TV672.3;TV544

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