弹性波法在西成客专桥梁基桩质量检测中的应用效果研究

发布时间：2018-12-18 04:24

【摘要】：在西成客专铁路桥梁的建设中,桩基础是一种非常重要的基础形式,尤其是以混凝土或钢筋混凝土为材料的混凝土灌注桩被广泛使用。但是桥梁基桩深埋地下,作为一项隐蔽工程,容易出现各种质量问题,对桥梁造成安全隐患。因此,对桥梁基桩进行质量检测颇为重要。本文采用现场实际检测与有限元数值模拟相结合的方法,对弹性波法用于西成客专桥梁工程中的基桩质量检测的有效性、准确性进行了系统研究。首先系统介绍了弹性波反射法检测桥梁基桩质量的基本理论,弹性波在桩内的传播机理,弹性波法的检测目的和适用范围,数据处理及缺陷判释原则。在数据处理方面,重点介绍了四种常用的信号后处理方法,包括数字滤波、指数增大、旋转修正,通过对比信号处理前后的效果,并采用时域分析的方法准确计算缺陷的具体位置,从而能够准确地对西成客专桥梁基桩的桩身完整性做出定性评价。其次在弹性波法检测基桩的理论基础上,利用大型有限元模拟软件ABAQUS对弹性波法基桩检测做激振瞬态模拟研究。起初介绍了ABAQUS的基本功能,包括模拟所用的处理模块和显式算法,以模拟弹性波在一维杆件内的传播为例,观察弹性波在杆内的传播过程,详细说明了ABAQUS建模和分析的过程；接下来以弹性波法检测完整摩擦桩为例,考虑到建模过程中所遇到的诸多问题,结合实际工程,对桩土模型进行优化,使得模拟的信号结果更加符合理论和实测情况；另外针对桥梁基桩可能遇到的各类质量问题,分析了西成客专铁路桥梁建设中应用较多的混凝土灌注桩的缺陷成因,分别对离析、扩颈、缩颈、断桩和桩底沉渣这五大类缺陷桩的检测做数值模拟,包括在不同位置设置缺陷,对比不同缺陷对应的桩顶测点速度时域信号特征的区别。最后对西成客专桥梁基桩质量检测的现场操作流程做了详细介绍,总结了弹性波法用于实测过程中的相关经验,包括检测前对桩顶的处理,设备测试参数的调整,传感器的安装以及检测过程中激振点和激振方式的选取等,接下来依托在西成客专汉中段用弹性波法实测的数据,对比完整桩和各类非完整桩的信号特征,对缺陷桩进行开挖验证,表明弹性波法用于西成客专桥梁基桩质量检测是切实可行的。
[Abstract]:Pile foundation is one of the most important foundation forms in the construction of railway bridge, especially the concrete cast-in-place pile with concrete or reinforced concrete as the material is widely used. However, as a hidden project, it is easy to produce various quality problems, which will cause hidden danger to the bridge. Therefore, it is very important to check the quality of bridge foundation pile. In this paper, the effectiveness and accuracy of the elastic wave method used in the quality detection of foundation pile in bridge engineering are systematically studied by the combination of field testing and finite element numerical simulation. Firstly, the basic theory of elastic wave reflection method for detecting the quality of bridge foundation pile, the propagation mechanism of elastic wave in pile, the purpose and scope of application of elastic wave method, the principle of data processing and defect interpretation are introduced systematically. In the aspect of data processing, four common methods of signal post-processing are introduced, including digital filtering, exponential increase, rotation correction, and comparison of the results before and after signal processing. The time domain analysis method is used to calculate the concrete position of the defect accurately, so that the pile integrity of the bridge foundation pile can be evaluated qualitatively. Secondly, on the basis of the theory of detecting foundation pile by elastic wave method, the transient simulation of exciting vibration is done by using the finite element simulation software ABAQUS. At first, the basic functions of ABAQUS are introduced, including the processing module and explicit algorithm used in simulation. Taking the simulation of elastic wave propagation in one-dimensional rod as an example, the propagation process of elastic wave in rod is observed, and the process of modeling and analysis of ABAQUS is explained in detail. Then take the elastic wave method to detect the intact friction pile as an example, considering the many problems encountered in the modeling process, combined with the actual engineering, the pile-soil model is optimized to make the simulated signal results more consistent with the theoretical and measured results. In addition, in view of the various quality problems that the bridge foundation pile may meet, this paper analyzes the causes of the defects of the concrete cast-in-place pile, which are widely used in the bridge construction of the Xicheng Special Railway, and separately analyzes the segregation, the expansion of the neck, and the contraction of the neck. The detection of broken pile and pile bottom sediment is numerically simulated, including setting defects in different positions, and comparing the characteristics of time-domain signal of velocity at the top of pile with different defects. At last, the paper introduces in detail the field operation flow of the quality test of the bridge foundation pile, summarizes the relevant experience of the elastic wave method in the process of the actual measurement, including the treatment of the pile top before testing, the adjustment of the testing parameters of the equipment. The installation of the sensor and the selection of excitation points and modes in the detection process, etc., then relying on the measured data of the Hanzhong section of Xicheng Special College using elastic wave method, the signal characteristics of the whole pile and all kinds of non-intact piles are compared. The excavation verification of the defective pile shows that it is feasible to apply the elastic wave method to test the quality of the foundation pile of the bridge.
【学位授予单位】：西南交通大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U446

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