基于数字测量技术的桥梁监测及预警系统

为了弥补传统测量手段在监测桥梁整体变形和长期实时监测的不足,克服基于单目视觉的数字摄影技术无法监测桥梁三维变形的缺陷,提出图像匹配-时间基线视差法。在适当位置布设观测站,架设数码相机,在距离数码相机不远处布设参考点组成参考平面,使得参考平面与摄影方向垂直,在桥梁上布设观测点。根据图像匹配-时间基线视差法求得变形点在物平面上的二维变形值,再利用三维变形监测原理将物平面上的水平变形分解到沿桥梁方向和垂直于桥梁方向,从而求得桥梁的三维变形。结果表明:桥梁变形点的监测精度在物平面上的X方向上为0.72 mm,在Z方向上为1.16 mm,能够满足变形监测的精度要求。凤凰山路桥在X, Y, Z以及综合方向上都表现出较好的弹性,且最大的正负挠度的绝对值之和为7.57 mm≈(1/8)×(L/1000)(桥梁挠度的容许变形),桥梁的健康状态良好。桥梁监测及预警系统能够实现数据获取、传输、存储、处理,以及结果展示一体化,且变形曲线图能够直观展示桥梁结构的变形走向,有效的预警潜在的危险。

Bridge monitoring and warning system based on digital measurement technology

In order to make up the deficiency of the traditional measuring method in monitoring the whole deformation and real-time monitoring of the bridge and overcome the defect of digital photography in monitoring the three-dimensional deformation of a bridge, this paper presented the image matching-time baseline parallax method: a digital camera was set up in the proper place, and a reference plane, consisting of reference points, was not far from the digital camera. Reference plane was perpendicular to the photographic direction, and the monitoring points were on the bridge. The two-dimensional deformation on the object plane of the deformation point was obtained based on image matching-time baseline parallax method, then the horizontal deformation on object plane was disassembled into the bridge direction and the direction perpendicular to bridge direction based on the principle of three-dimensional deformation monitoring, The three-dimensional deformation of the bridge was got. Results showed that measurement accuracy of the bridge was 0.72 mm and 1.16 mm in X and Z direction on object plane, respectively. It could meet accuracy requirements of deformation monitoring. As Phoenix mountain road-bridge showed good flexibility in X, Y, Z and comprehensive direction, and the absolute of the maximum positive and negative deflection was 7.57 mm, which was approximately equal to 1/8 of the allowable deflection of the bridge (L/1 000), and the bridge was in good health. Bridge health monitoring and warning system could achieve the integration of data acquisition, storage, processing and display. The deformation curves could show the deformation trend of the bridge and effectively warn the potential danger.