冲击回波法检测预应力孔道灌浆的应用研究

发布时间：2018-01-03 10:42

本文关键词：冲击回波法检测预应力孔道灌浆的应用研究　出处：《东北林业大学》2014年硕士论文　论文类型：学位论文

【摘要】：预应力混凝土结构由于截面小、刚度大、抗裂性和耐久性好、综合经济效益好等优点,在世界各地的建筑领域中得到了广泛应用,我国新建的桥梁95%以上都采用预应力混凝土梁。孔道灌浆的质量直接关系到预应力构件的稳定性及耐久性,但孔道灌注后即成为暗箱,质量不易检查,一旦出现事故,其所带来的经济损失和危害是巨大的。预应力孔道灌浆质量的健康诊断一直以来都是该领域研究的重点和难点,而现有的检测方法不能很好的识别孔道内部缺陷,如取芯法会损坏结构,雷达法易受钢筋及金属波纹管的干扰,射线法安全性和操作性差,超声检测必须双面测试,但冲击回波法这种新型无损检测方法却可以克服这些困难。如果能将冲击回波法应用到灌浆质量的识别和预控制中,无疑是一次重大创新。本文依托有限元数值模拟和现场模型试验,对冲击回波法应用于后张预应力孔道灌浆质量的检测展开研究。首先,针对预应力孔道的特点和目前检测方法存在的问题,查阅大量国内外相关文献,阐述了论文的选题背景与意义,对国内外相关领域的发展情况作了介绍。其次,介绍应力波的基础理论,详细阐述应力波在介质中的传播规律及其在不同阻抗界面的反射与透射,介绍冲击回波检测的基本原理与操作方法。再次,运用有限元分析软件ANSYS/LS-DYNA进行数值模拟,分析应力波在不同灌浆情况的模型表面及内部的传播特性,验证冲击回波法检测的可靠性。对表面节点的速度时程曲线进行傅里叶变换得到频谱图,分析典型缺陷的关键频率特征,并为后续的现场模型试验提供理论支撑。最后,针对预应力孔道典型病害制作模型,得到了不同缺陷情况的检测结果,分析关键频率的特征,提出了一套用于实际工程的测试方案。检测结果基本能与预先设置的缺陷相吻合,与有限元模拟结果也体现了良好的一致性,进一步提高了其在实际工程中的地位,为将来的研究提供参考。
[Abstract]:The prestressed concrete structure due to the small cross section, stiffness, crack resistance and durability is good, has the advantages of good economic efficiency, has been widely used in the world in the field of construction, more than 95% bridges built in our country in the use of prestressed concrete beams. The grouting quality is directly related to the stability and durability of prestressed concrete members but, after a secret channel perfusion, the quality is not easy to check, once an accident occurs, economic losses and the consequent harm is enormous. The health diagnosis of prestressed grouting quality has always been the focus and difficulty of research in this field, and the existing detection methods can not identify the channel internal defects of good, such as coring method will damage the structure of radar interference and reinforced metal bellows, ray method safety and maneuverability, ultrasonic testing must be two-sided test, but the impact of this new type of back wave method NDT methods can overcome these difficulties. If the impact echo method is applied to the identification and pre grouting quality control, is undoubtedly a major innovation. Based on the finite element numerical simulation and field model tests, research on detection of impact echo method applied in post tensioning prestressed grouting quality.
First, according to the characteristics of prestressed ducts and the existing problems in current detection methods, we consulted a large number of related documents at home and abroad, elaborated the background and significance of the topic selection, and introduced the development of related fields both at home and abroad.
Secondly, the basic theory of stress wave is introduced. The propagation law of stress wave in medium and its reflection and transmission at different impedance interfaces are described in detail. The basic principle and operation method of impact echo detection are introduced.
Again, using finite element analysis software ANSYS/LS-DYNA, numerical simulation, analysis of the propagation characteristics of surface and internal model of stress wave at different filling conditions, reliability verification of impact echo method. The curves of surface nodes when the speed of the Fourier transform to obtain the frequency spectrum analysis of key frequency characteristics of typical defects, and to provide theoretical field model test in the future.
Finally, according to the typical diseases of prestressed duct model, the detection results of different defects, analysis of the characteristics of the key frequency, a new test scheme for practical engineering is proposed. The detection results can match with the preset defects, results and finite element simulation also shows good consistency, further improve its position in the actual engineering, provide a reference for future research.

【学位授予单位】：东北林业大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U445.57

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