基于冲击回波法与支持向量机的预应力管道压浆质量评定

发布时间：2018-04-23 06:48

本文选题：冲击回波法 + 板结构　；参考：《湖南大学》2014年硕士论文

【摘要】：自20世纪80年代以来，后张法有粘结预应力混凝土结构以其特有的优势主导了我国桥梁工程建设。然而，由于管道压浆质量得不到有效控制，预应力筋很容易遭到腐蚀，由此带来的结构安全问题日益严重。因此，工程技术人员需要一种方便、有效的检测方法对管道压浆质量进行鉴定。冲击回波法是一种基于瞬态冲击作用的无损检测方法，，基于该方法，本文开展了预应力管道压浆质量检测技术的理论和试验研究，主要包括以下工作： 1.介绍了冲击回波法发展历史及应用现状，简要论述了该方法在板结构检测中的理论依据;叙述了板结构在瞬态冲击作用下的简化模拟方法。 2.通过数值仿真计算，研究了空管工况下响应频幅曲线特征随模型参数及测试环境的变化，研究结果表明：（1）当孔厚比大于等于0.4时，缺陷深度频率峰值才能从响应频幅曲线中分辨出来；过大的孔厚比引起测点处R波与反射P波的互相干扰会造成缺陷频率峰值的严重降低；（2）当冲击作用点由管道中心线上方逐渐偏移时，板厚频率峰值在不同的偏移范围内表现出三种典型的响应特征；（3）空管工况下，板厚频率漂移率为孔厚比的函数。 3.总结实际工程中常见五类测试工况，对各工况冲击回波信号进行了特征抽取，并基于支持向量机技术建立了五类典型测试工况的分类模型。 4.通过室内试验研究，对有限元计算结果及分类模型有效性进行了初步验证。总结了冲击回波检测法的优缺点，对该方法的未来发展作了初步探讨。
[Abstract]:Since 1980's, post- bonded prestressed concrete structure has dominated the construction of bridge engineering in China with its unique advantages. However, because the quality of pipeline grouting can not be effectively controlled, the prestressed tendons are vulnerable to corrosion, and the structural safety problems are becoming more and more serious. Therefore, engineers need a convenient and effective method to identify the quality of pipeline grouting. Impact echo method is a kind of nondestructive testing method based on transient impact. Based on this method, the theoretical and experimental research of pre-stressed pipeline grouting quality detection technology is carried out, including the following work: 1. This paper introduces the history and application status of impact echo method, briefly discusses the theoretical basis of this method in plate structure detection, and describes the simplified simulation method of plate structure under transient impact. 2. Through numerical simulation, the variation of response frequency curve characteristics with model parameters and test environment is studied. The results show that the ratio of hole to thickness is greater than 0.4 when the ratio of hole to thickness is greater than 0.4. The peak frequency of defect depth can be distinguished from the response frequency amplitude curve. The interference between R wave and reflected P wave at measurement point caused by excessive hole thickness ratio will result in a serious reduction of the peak frequency of defect.) when the impact action point is gradually shifted from the top of the central line of the pipeline, The peak frequency of plate thickness shows three typical response characteristics in different offset range. The frequency drift rate of plate thickness is a function of hole thickness ratio under the condition of empty tube. 3. In this paper, five kinds of test conditions are summarized, and the feature extraction of shock echo signal is carried out. The classification model of five typical test conditions is established based on support vector machine technology. 4. The results of finite element calculation and the validity of the classification model are preliminarily verified by laboratory experiments. The advantages and disadvantages of impulse echo detection are summarized, and the future development of the method is discussed.
【学位授予单位】：湖南大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U445.57

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