基于InSAR技术的大跨桥梁温度变形监测研究

以国内某高速铁路钢拱桥为研究对象,选取2017—2018年期间59幅C波段Sentinel-1号雷达卫星影像,利用PS-InSAR技术处理影像获得桥梁的视线向（Line of Sight,LOS）位移,根据SAR成像空间几何关系解算出支座的纵向位移. 研究结果表明：支座纵向位移的时空特性与实际桥梁结构相符合,验证了PS-InSAR技术观测桥梁结构位移的可行性. 建立支座纵向位移与温度的线性相关模型,并与结构健康监测系统的实测结果进行对比. 两者吻合良好,相对误差控制在10%以内,验证了PS-InSAR测量桥梁结构位移的可靠性. 利用有限元模拟温度作用下桥梁支座的位移变化,并与PS-InSAR位移时间序列进行对比. 两者趋势基本一致,LOS向位移误差在［-10,10］ mm,验证了PS-InSAR测量桥梁结构位移的准确性.

Research on Temperature Deformation Monitoring of Long-span Bridges Based on InSAR Technology

Structural health monitoring is an effective means to ensure the safe operation and maintenance of bridges and optimize the life cycle cost of bridges. Persistent Scatterer Interferometric Synthetic Aperture Radar （PS-InSAR） technology based on spaceborne synthetic aperture radar can realize long-term structural health monitoring of bridges with low cost, light weight and sustainability. In this paper, a high-speed railway steel arch bridge in China is taken as the research object, and 59 C-band Sentinel-1 radar satellite images from 2017 to 2018 are selected. The PS-InSAR technology is used to process the images to obtain the line of sight （LOS） displacement of the bridge, and the longitudinal displacement of the bearing is calculated according to the spatial geometric relationship of SAR imaging. The results show that the spatial and temporal characteristics of the longitudinal displacement of the bearing are consistent with the actual bridge structure, which verifies the feasibility of PS-InSAR technology to observe the displacement of the bridge structure. A linear correlation model between the longitudinal displacement of the bearing and the temperature is established and compared with the measured results of the structural health monitoring system. The two are in good agreement, and the relative error is close to 10 %, which verifies the reliability of PS-InSAR measurement of the bridge structure displacement. The displacement of the bridge bearing under the action of temperature is simulated by finite element method, and compared with the PS-InSAR displacement time series. The two trends are basically the same, and the LOS displacement error is within ［-10,10］ mm, which verifies the accuracy of PS-InSAR measurement of bridge structure displacement.