HHT方法在地基雷达监测数据处理中的应用

发布时间：2018-04-15 15:06

本文选题：地基微波干涉雷达 + IBIS系统　；参考：《北京建筑大学》2017年硕士论文

【摘要】：地基微波干涉雷达集成步进频率连续波技术、合成孔径雷达技术和干涉测量技术,采用非接触式的测量方式,获取实时的动态监测数据,成为变形监测领域一种新型监测技术。本文基于意大利IDS公司生产的地基干涉雷达IBIS系统展开相关研究工作,进行了系统综合性能测试、希尔伯特-黄变换理论研究及其在地基雷达数据处理中的应用研究。主要内容如下:1、IBIS系统综合性能测试。利用角反射器与螺旋测微器的组合装置模拟变形,检测IBIS系统测量精度,结果表明其精度优于亚毫米级。为保证IBIS系统监测精度,进一步研究仪器安置误差和大气因素误差的影响,利用实验与数据模拟的方法证明安置仪器时仰角、距离对观测精度的影响,并通过采集的气象数据,证明大气因素对观测结果存在影响,需要应用大气参数模型对观测结果进行改正。2、IBIS系统动态监测应用。采用IBIS系统对某高速铁路桥梁进行了形变动态测量研究,对简支箱梁、大跨度的连续现浇梁、桥墩及声屏障等桥梁关键结构进行多期的测量,获得了测量对象的动态位移序列。此外,应用IBIS系统完成了通州燃灯古塔的监测项目,设计了对高耸建筑的监测方案和数据处理方法。结合桥梁监动态监测方案总结了完整的IBIS动态监测体系。3、基于希尔伯特—黄变换(HHT)理论,针对地基雷达IBIS系统所获取的非线性、非稳态的振动信号,进行了分析研究:(1)经验模态分解(EMD)振动信号重构。针对动态测量结果受到高频噪声的影响,采用具有自适应性信号处理方法EMD对地基雷达原始信号进行降噪处理。将原始信号分解为由高频至低频的一系列本征模态函数(IMF),利用相关系数判定噪声界限,将各IMF重构成为噪声序列、周期序列和趋势序列。与原始信号相比,重构的周期序列可以更精确反映建筑物的振动细节和周期变化。(2)HHT模态参数识别。为获得高速铁路桥梁在列车激励作用下的有载频率,应用HHT理论将原始信号分解为表示振动响应的本征模态函数(IMF),通过Fourier频谱图考察振动响应的主模态,利用随机减量技术(RDT),提取主模态振动响应中的确定性信号并进行Hilbert变换,进而识别在激励作用下建筑物振动的固有频率。在地基雷达数据处理过程中,与HHT理论进行有机结合,可以有效的剔除噪声影响,获取真实的位移数据,精确识别建筑物模态参数,为建筑物的健康评估提供科学、准确的依据,从而证明了将HHT理论应用于处理地基雷达数据具有良好的适用性。
[Abstract]:The ground-based microwave interferometric radar integrated step frequency continuous wave technology, synthetic aperture radar technology and interferometric measurement technology, using non-contact measurement method to obtain real-time dynamic monitoring data, become a new monitoring technology in the field of deformation monitoring.Based on the IBIS system of ground interference radar produced by IDS company in Italy, the comprehensive performance of the system is tested, and the theory of Hilbert-Huang transform and its application in ground radar data processing are studied in this paper.The main contents are as follows: 1: 1 IBIS system comprehensive performance test.The combined device of angle reflector and spiral micrometer is used to simulate the deformation to detect the measuring accuracy of IBIS system. The results show that the accuracy of the system is superior to that of sub-millimeter.In order to ensure the monitoring accuracy of IBIS system and further study the influence of instrument placement error and atmospheric factor error, the influence of elevation angle and distance on the observation accuracy is proved by means of experiment and data simulation, and the meteorological data are collected.It is proved that the atmospheric factors have influence on the observed results, and the atmospheric parameter model should be used to correct the observed results.The deformation dynamic measurement of a high-speed railway bridge is studied by using IBIS system. The dynamic displacement sequence of the measuring object is obtained by measuring the key structures of the bridge, such as simply supported box girder, long-span continuous cast-in-situ beam, piers and sound barrier, etc.In addition, the IBIS system is used to complete the monitoring project of the ancient tower of Tongzhou fuel lamp, and the monitoring scheme and data processing method of the towering building are designed.Based on Hilbert-Huang transform (HHT) theory, this paper sums up the complete dynamic monitoring system of IBIS combined with the dynamic monitoring scheme of bridge supervision, aiming at the nonlinear and unsteady vibration signals obtained by the IBIS system of ground-based radar.In this paper, the reconstruction of EMD-1 vibration signal by empirical mode decomposition (EMD) is studied.In view of the effect of high frequency noise on the dynamic measurement results, the adaptive signal processing method (EMD) is adopted to reduce the noise of the original signal of ground-based radar.The original signal is decomposed into a series of intrinsic mode functions from high frequency to low frequency. The correlation coefficient is used to determine the noise limit and the IMF is reconstructed into noise sequence, periodic sequence and trend sequence.Compared with the original signal, the reconstructed periodic sequence can more accurately reflect the vibration details of the building and the periodic variation.In order to obtain the loaded frequency of high-speed railway bridge under train excitation, the original signal is decomposed into the intrinsic mode function of vibration response by using HHT theory, and the main mode of vibration response is investigated by Fourier spectrum diagram.By using random decrement technique, deterministic signals are extracted from the vibration response of the main mode and Hilbert transform is carried out to identify the natural frequencies of the vibration of buildings under excitation.In the process of ground radar data processing, combining with HHT theory, it can effectively eliminate the influence of noise, obtain real displacement data, identify the modal parameters of buildings accurately, and provide a scientific method for building health assessment.It is proved that the application of HHT theory to ground-based radar data processing has good applicability.
【学位授予单位】：北京建筑大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：U446

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