PC箱梁桥竖向预应力张拉力与压浆密实性无损检测技术研究
发布时间：2018-12-13 19:08
【摘要】：大跨径预应力混凝土箱梁桥腹板设置竖向预应力筋的主要目的在于抵抗腹板的主拉应力和剪力,从而达到防止箱梁腹板开裂的目的。但是,箱梁桥腹板斜裂缝病害却始终存在。一方面是由于竖向预应力张拉过程中操作不当、预应力筋定位误差大以及预应力筋回缩等原因造成的锚固后实际张拉力不足；另一方面是由于竖向预应力管道压浆不密实造成竖向预应力筋锈蚀产生预应力损失导致的实际张拉力不足。因此,如何提高竖向预应力筋的张拉质量及减小运营期长期损失以提供足够的张拉力,成为研究重点。本文针对竖向预应力筋张拉力及管道压浆密实度进行了数值分析及模型试验研究,主要研究工作如下：1)本文详细阐述了选题背景、目的意义。介绍了国内外学者对竖向预应力张拉力和管道压浆密实度无损检测方法的研究现状。2)根据结构动力学理论分别通过公式推导与有限元数值模拟的方法对竖向预应力钢筋外露段的频率特性进行了对比分析。3)通过模型试验获得φ32精轧螺纹钢筋实际张拉力与锚固段刚度增大系数之间的经验公式,并将研究成果应用于实桥,有效提高了竖向预应力张拉质量。4)简要介绍弹性波及冲击回波法基本原理,对冲击回波时域信号转换为频域信号的傅里叶变换进行简单说明。同时,根据弹性波纵波传播理论详细分析了纵波在五种压浆密实程度下的传播路径。5)进行了现场模型试验,模拟了不同厚度下全空、1/4密实、1/2密实、3/4密实、完全密实五种压浆工况,并测试其冲击回波主频。试验结果与有限元数值分析结果一致,即冲击回波主频与管道压浆密实度均呈现显著的线性关系。6)根据有限元数值分析结果得到了冲击回波主频与管道压浆密实度在一定参数下的经验公式,并利用该经验公式进行了竖向预应力孔道压浆密实性的定量评估。
[Abstract]:The main purpose of installing vertical prestressed tendons on the web plate of long-span prestressed concrete box girder bridge is to resist the main tensile stress and shear force of the web so as to prevent the box girder web from cracking. However, the box girder bridge web slant crack disease has always existed. On the one hand, the actual tension after anchoring is insufficient due to improper operation in the process of vertical prestressing tensioning, large positioning error of prestressed tendons and retraction of prestressed tendons. On the other hand, the actual tensile force is insufficient due to the corrosion of the vertical prestressed tendons caused by the uncompacted grouting of the vertical prestressed pipes. Therefore, how to improve the tensioning quality of vertical prestressed tendons and reduce the long-term losses in operation to provide enough tension has become the focus of research. In this paper, the tensile force of vertical prestressed tendons and the density of pipe grouting are studied by numerical analysis and model test. The main research work is as follows: 1) the background and purpose significance of this paper are described in detail. This paper introduces the research status of nondestructive testing methods for vertical prestressing tension and grouting compactness of pipeline at home and abroad. 2) according to the theory of structural dynamics, the vertical tension is derived by formula derivation and finite element numerical simulation, respectively. The frequency characteristics of the exposed segment of prestressed steel bar are compared and analyzed. 3) the empirical formula between the actual tensile force of 蠁 32 finish rolled rebar and the increasing coefficient of stiffness of anchoring section is obtained by model test. The research results are applied to the real bridge, which effectively improves the quality of vertical prestressing tension. 4) the basic principle of elastic wave and impact echo method is briefly introduced, and the Fourier transform from the time domain signal of impact echo to the frequency domain signal is simply explained. At the same time, according to the theory of elastic wave P-wave propagation, the propagation paths of P-wave under five kinds of slurry compactness are analyzed in detail. 5) the field model test is carried out, and the whole space, 1 / 4 density, 1 / 2 density under different thickness are simulated. 3 / 4 compactness, complete compactness, five grouting conditions, and test the main frequency of shock echo. The experimental results are consistent with the results of finite element numerical analysis. That is, the linear relationship between the main frequency of shock echo and the grouting density of pipeline is obvious. 6) based on the results of finite element numerical analysis, the empirical formula of the main frequency of shock echo and the degree of slurry compactness of pipeline under certain parameters is obtained. The empirical formula is used to quantitatively evaluate the compactness of vertical prestressing channels.
【学位授予单位】：山东大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U445.57
本文编号：2377067
[Abstract]:The main purpose of installing vertical prestressed tendons on the web plate of long-span prestressed concrete box girder bridge is to resist the main tensile stress and shear force of the web so as to prevent the box girder web from cracking. However, the box girder bridge web slant crack disease has always existed. On the one hand, the actual tension after anchoring is insufficient due to improper operation in the process of vertical prestressing tensioning, large positioning error of prestressed tendons and retraction of prestressed tendons. On the other hand, the actual tensile force is insufficient due to the corrosion of the vertical prestressed tendons caused by the uncompacted grouting of the vertical prestressed pipes. Therefore, how to improve the tensioning quality of vertical prestressed tendons and reduce the long-term losses in operation to provide enough tension has become the focus of research. In this paper, the tensile force of vertical prestressed tendons and the density of pipe grouting are studied by numerical analysis and model test. The main research work is as follows: 1) the background and purpose significance of this paper are described in detail. This paper introduces the research status of nondestructive testing methods for vertical prestressing tension and grouting compactness of pipeline at home and abroad. 2) according to the theory of structural dynamics, the vertical tension is derived by formula derivation and finite element numerical simulation, respectively. The frequency characteristics of the exposed segment of prestressed steel bar are compared and analyzed. 3) the empirical formula between the actual tensile force of 蠁 32 finish rolled rebar and the increasing coefficient of stiffness of anchoring section is obtained by model test. The research results are applied to the real bridge, which effectively improves the quality of vertical prestressing tension. 4) the basic principle of elastic wave and impact echo method is briefly introduced, and the Fourier transform from the time domain signal of impact echo to the frequency domain signal is simply explained. At the same time, according to the theory of elastic wave P-wave propagation, the propagation paths of P-wave under five kinds of slurry compactness are analyzed in detail. 5) the field model test is carried out, and the whole space, 1 / 4 density, 1 / 2 density under different thickness are simulated. 3 / 4 compactness, complete compactness, five grouting conditions, and test the main frequency of shock echo. The experimental results are consistent with the results of finite element numerical analysis. That is, the linear relationship between the main frequency of shock echo and the grouting density of pipeline is obvious. 6) based on the results of finite element numerical analysis, the empirical formula of the main frequency of shock echo and the degree of slurry compactness of pipeline under certain parameters is obtained. The empirical formula is used to quantitatively evaluate the compactness of vertical prestressing channels.
【学位授予单位】：山东大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U445.57
【参考文献】
相关期刊论文 前1条
1 李海军,李军;连续梁桥预应力箱梁腹板裂缝成因浅析[J];华东公路;2000年03期
，本文编号：2377067
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