【作者】 甘维兵；

【导师】 姜德生；

【作者基本信息】 武汉理工大学 ， 信息与通信工程， 2017， 博士

【摘要】 桥梁是公路的咽喉,是交通运输系统中的枢纽工程,在日益发达的国民经济中扮演着越来越重要的角色。随着各种结构新颖、跨径庞大、体系复杂的大型桥梁逐渐涌现,桥梁结构健康监测和安全评估受到了越来越广泛关注。在诸多影响桥梁结构健康安全因素中,结构线形是评价桥梁安全状况最关键的参数之一,它能够反演结构内力变化,是结构几何形态安全检测的重要指标,是评价桥梁运营状态的关键因素。传统测量方法如千分表、水准仪、GPS、激光车载系统等常规设备只能测量有限点或局部信息,且户外作业量大,布点受环境和地形条件限制,不易较好地实现自动化测量,难以满足大规模桥群对快速、高精度线形测量的需求。武汉理工大学光纤传感技术国家工程实验室于2011年开展探索桥梁结构线形检测新方法,随后提出了基于光纤惯性传感技术的桥梁结构线形检测新思路。经过长达多年的研究,从理论和实践上证明了该方法的可行性,但真正能否用于工程实际,取决于一系列关键技术能否得到突破,如系统可靠性、绝对测量精度以及抗干扰能力等。为此,本文针对如何提高系统绝对测量精度、增强抗干扰能力等关键技术进行了深入探讨,提出了一系列的手段和方法,并通过实际工程应用对其进行论证,解决了系统绝对测量精度不高、抗外界干扰能力不足等问题,从而实现真正意义上的快速、连续、精确线形测量。本文的主要研究内容及结果如下:(1)采用新算法提高了光纤陀螺用于桥梁结构线形检测绝对测量精度。通过对光纤陀螺用于线形检测的基本原理进行分析,研究将运载体视为质点的近似算法给线形测量结果带来的误差影响,设计了一种基于割线算法的微小形变检测新算法,该算法基于承载平台与待测曲线的割线相平行,无需考虑运载体前、后轮间距大小,均能客观、准确地反映待测结构实际线形。(2)采用首尾约束、桥墩固定点标定等方法有效降低和抑制了光纤陀螺固有特性和运载体自身因素给测量带来的误差影响,实验结果表明以上方法能够有效地对系统测量过程中存在的各种内在误差进行校正和处理,显著提高了系统绝对测量精度。(3)采用小波筛选和数据重构的方法有效地解决了线形检测系统抗路面颠簸、振动等干扰问题。设计了一种适合光纤陀螺输出特性的小波算法对系统因路面不平整而产生的奇异数据进行筛选处理,抑制误差积累影响,从而提高系统抗干扰能力。与此同时,采用伪随机信号对奇异数据段进行重构,从而确保桥梁结构线形检测的真实性、连续性和完整性。(4)验证了光纤线形检测系统用于桥梁线形测量的可靠性、微小形变检测能力以及抗垂直振动干扰能力。通过多工况下的模型桥梁逐级静态加载实验,检验光纤线形系统各项性能指标,实验结果表明:系统重复性良好、测量精度达到毫米级、能够准确定位跨中最大下挠、不敏感垂直方向的角速度变化,特别适合于易受外界环境(台风、暴雨等)影响而产生垂直振动的特大跨桥梁动态线形检测。(5)将光纤线形检测系统应用于几大典型工程,实现对既有桥梁结构最大下挠的诊断及新建大跨桥梁结构承载能力测试,取得了良好的效果。光纤线形检测系统能够较好地实现全桥结构连续线形测量,不遗漏结构任何病害处,能够准确定位结构最大下挠和测量最大形变值,为既有桥梁结构病害筛选与诊断提供强有力的数据支撑;通过该系统对新建桥梁在各种加载工况下的几何线形进行测试,并辅以水准仪进行复核,结果表明该系统能够准确测量荷载下的全桥连续形变曲线。对于主跨达到千米级的特大跨桥梁,当跨中加载形变达到米级时,其测量精度可以达到厘米级,且加载前后主梁形变的对称性能够很好地反映桥梁结构的几何形态。更多还原

【Abstract】 Bridges are critical links within transportation networks.Bridge performance and deterioration have been of great concern to owners and maintenance engineers for many years.Therefore,more and more novel designs and complicated structural components for long-span and modern bridges structures have been employed.The requirements for Structural Health Monitoring system have been highly improved.Several different types of transducers can be used to measure the deflection,including netsuke,dial indicator,level gauge,electronic total station,Global Positioning System(GPS),and photogrammetric techniques.However,most of the traditional methods(netsuke,dial indicator,level gauge,electronic total station,GPS)require point-by-point personnel handling or the access to measurement location on bridges.As a result,the traffic of the bridge will be interrupted normally for the setup of these transducers.In addition,the installation of these transducers is time-consuming.It is impossible to perform efficient measurements for a huge amount of bridges.A new method based on fiber optic inertial sensor for bridge structural curve deflection measuring was proposed in 2011 by National Engineering Laboratory for Fiber Optic Sensing Technology,Wuhan University of Technology.The feasibility of this method has been proved in theory and practice.A series of improvements are required to enhance the reliability and absolute accuracy of the system for engineering applications.This thesis will focus on a series of methods to put this technology forward to the field applications.The main works of this thesis will be listed as following:Firstly,a new algorithm is discussed theoretically to improve the accuracy of the FOG-based deflection measuring method.Based on the analysis of the basic principle of the fiber optic gyroscope used in line detection,the paper discusses the influence of the vehicle length induced error and proposes a new algorithm based on the secant line to reduce error.A secant line between the front and back wheels of the vehicle is built for the new algorithm to replace the previous approximation in which the vehicle is regarded as a point.The deviation improvements of the new algorithm are discussed thoroughly.The algorithm is able to measure the accurate trajectory,especially for the curve with a curvature comparable with the vehicle length.The zero bias error and random divergence error of the fiber optic gyro used in bridge structure detection are suppressed and reduced.In this paper,two calibration method,the start/end-point and fixed-point calibration,are used to reduce the errors of gyro error effects on measurement.The experimental results show that the above methods can correct effectively the inherent errors during the measuring process,and improve the absolute accuracy of the final results.Data manipulation and processing methods are used to overcome the influence of the external vibration interference caused by roughness and bumps on the road pavement to the linear detection system.In this paper,a wavelet algorithm is designed for de-noising of FOG data and to pick up the singularities.At the same time,the pseudo random signal is used to reconstruct the singular data segment,so as to ensure the authenticity,continuity and integrity of the curve measuring.This paper discusses the reliability of the system by investigating the measurement on tiny deformation and the performance with the vertical vibration by using a scale model of long-span bridge.The system is used to detect the static loading experiment of bridge model step by step,and compared with the test data of dial indicator.The experimental results show that the system has good repeatability,with a scale of millimeter.It can accurately locate the maximum deflection in the span and the angular velocity of the insensitive vertical direction.Several examples in field have been presented for both the new bridges and existing bridges.Generally,the system can provide the whole continuous curve of existing or new long-span bridges.On one side,the data will contribute to the disease diagnosis and health monitoring of existing bridge,with the capability to locate accurately the maximum deflection.On the other side,the system is applied to measure the geometric alignment of the new bridge under various load test.The results show that the measurement accuracy of the system can reach centimeter level.For the existing bridges,the location of the maximum deflection will be diagnosed.For new bridge,the comparing between the deformation of the main beam before and after load test can provide the essential information for the health status evaluation of bridges.更多还原