冻融循环下混凝土力学性能试验及损伤演化研究

发布时间：2018-03-25 20:34

本文选题：混凝土　切入点：冻融循环　出处：《长安大学》2015年硕士论文

【摘要】：混凝土作为一种常见的多相复合材料,因其所具有的较多优点,而广泛应用于各工程领域。有研究表明钢筋腐蚀、冻融循环以及侵蚀环境的物理化学作用是影响混凝土耐久性能的三个重要因素,其中冻融循环对混凝土耐久性的影响愈来愈被人们所重视。特别是在我国西部寒区,冻融循环作用往往是导致混凝土破坏的主要因素之一。因此,深入研究混凝土冻融损伤破坏过程具有非常重要的理论价值和工程实际意义。论文以西部寒区混凝土材料为研究背景,将混凝土冻融循环试验、宏观力学试验和细观CT扫描试验相结合,对混凝土材料在冻融循环下的破损机理开展研究,并利用有限元ANSYS软件对冻融循环下混凝土进行了数值模拟。以期更为深入地研究混凝土冻融损伤劣化机理以及破坏规律,为寒区重大工程冻融灾变预测和防治提供较可靠的试验与理论依据。论文研究的主要内容如下:(1)对制备的混凝土试样进行冻融循环试验,并对不同冻融循环次数下的混凝土试样进行单轴压缩试验以及三点弯曲试验。通过研究混凝土弹性模量、抗压强度、抗弯强度、应力-应变等力学特性的变化规律,探索了混凝土的宏观力学性能与不同冻融循环次数的变化规律;(2)应用CT技术对冻融循环下混凝土试样的破损全过程进行追踪,获得了不同冻融循环次数下混凝土细观结构变化特征。通过运用图像处理技术初步分析了冻融循环下混凝土细观损伤扩展的演化过程;并以图像中CT均值的变化为基础,建立了基于细观统计力学的损伤变量与冻融循环的关系曲线,以此对冻融循环条件下混凝土细观结构的损伤演化规律及破损机理进行了定量研究;(3)利用有限元ANSYS软件对冻融循环下混凝土试样进行了数值模拟,并对不同冻融循环次数下混凝土的温度场分布云图以及温度应力分布云图进行了分析,进而验证了数值模拟的可行性。
[Abstract]:As a common multiphase composite material, concrete is widely used in various engineering fields because of its many advantages. The physical and chemical effects of freeze-thaw cycle and erosive environment are three important factors that affect the durability of concrete. The influence of freeze-thaw cycle on the durability of concrete is paid more and more attention, especially in the cold region of western China. Freeze-thaw cycles are often one of the main factors leading to concrete failure. It is of great theoretical value and practical significance to study the damage and failure process of concrete in freezing and thawing. In this paper, the freeze-thaw cycle test of concrete is carried out under the background of concrete materials in the western cold region. The damage mechanism of concrete material under freeze-thaw cycle was studied by combining macroscopic mechanical test and mesoscopic CT scan test. The numerical simulation of concrete under freeze-thaw cycle is carried out by using finite element ANSYS software, in order to study the mechanism of damage deterioration and failure law of concrete under freeze-thaw cycle more deeply. This paper provides a reliable experimental and theoretical basis for the prediction and prevention of freezing and thawing disasters in major projects in cold regions. The main contents of this paper are as follows: 1) Freeze-thaw cycle tests are carried out on concrete samples prepared. The uniaxial compression test and three-point bending test of concrete samples with different freeze-thaw cycles were carried out. The variation of mechanical properties of concrete such as elastic modulus, compressive strength, flexural strength, stress-strain and so on were studied. The macroscopic mechanical properties of concrete and the variation law of different freeze-thaw cycles are explored. The whole damage process of concrete samples under freeze-thaw cycle is tracked by CT technique. The variation characteristics of concrete meso-structure under different freeze-thaw cycles are obtained. The evolution process of concrete meso-damage propagation under freeze-thaw cycle is analyzed by using image processing technology, and the change of CT mean value in the image is used as the basis. The relationship curve between damage variable and freeze-thaw cycle based on meso-statistical mechanics is established. The damage evolution law and damage mechanism of concrete mesostructures under freeze-thaw cycle are studied quantitatively. The numerical simulation of concrete samples under freeze-thaw cycle is carried out by using finite element ANSYS software. The distribution of temperature field and temperature stress of concrete under different freeze-thaw cycles are analyzed, and the feasibility of numerical simulation is verified.
【学位授予单位】：长安大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU528

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