某人行桥整体构形的三维激光扫描检测方法

A 3D Laser Scanning Method for Detecting Overall Configuration of a Pedestrian Bridge

为了研究桥梁在设计、建设、运营阶段因为各种因素产生变形的检测方法,避免传统检测方法的缺陷,解决数据采集和数据处理两方面的问题。针对某运营期人行桥,采用了Laica Scan Station P40三维激光扫描仪对其整体构形进行了检测,该仪器具有快速性、非接触性、主动性,实时地获取数据且有高密度、高精度等特点,并不受光线限制。在数据采集方面,通过几何分析方法分析了测站间距、扫描入射角、扫描分辨率等关键扫描参数的优化方法,以保证扫描精度,并经实例验证利用该方法设置测站与扫描率获取点云质量良好。在点云数据处理方面,结合点云配准、去噪、压缩等预处理算法,采用了逆向建模技术给出了该复杂结构桥梁运营期的整体构形,分析了其与设计理论成桥状态构形之间的构形偏差,并根据获取的点云数据经过拟合计算得到复杂构件的构形。将该复杂结构桥梁运营期的模型与设计理论成桥状态的模型对比发现:该桥主缆整体向下变形,向内侧倾斜,并且边跨主缆变形较大;桥塔向跨中倾斜;梁体跨中断面向下变形,边跨变形大于中跨变形。结果表明:3D激光扫描技术可精确获得桥梁在某时刻的整体空间构形,通过激光扫描技术建立其电子档案,可用于评估其健康状态随运营时间的变化情况,为全面分析复杂结构桥梁及其各构件的运行状态提供技术资料。

In order to study the method for detecting bridge deformation caused by various factors in design,construction and operation stages,to avoid the defects of traditional detection methods,and to solve the problems of data collection and data processing,for a pedestrian bridge during operation period,the Laica Scan Station P403D laser scanner with fast,non-contact,proactive,real-time data acquisition,highdensity,high-precision,and not limited by light,is used to detect the overall configuration.In terms of data collection,the methods for optimizing the key scanning parameters such as station spacing,scanning incident angle,and scanning resolution are analyzed by geometric analysis method to ensure the scanning accuracy.It is verified by example that using this method to set the station and scan rate,the obtained point cloud is of good quality.In terms of point cloud data processing,the overall configuration of this complex structure bridge during the operation period is given by using inverse modeling technology combining with point cloud registration,denoising,compression,etc.The deviation between this configuration and the configuration of designed bridge completion state is analyzed,and the configuration of the complex component is obtained through fitting calculation according to the obtained point cloud data.After the comparison between the model of the complex structure bridge during operation period and the model of the designed bridge completion state,it is found that(1)the main cable of the bridge is deformed downward and tilted inward,and the main cable of the side span is deformed greatly;(2)the pylon is tilted toward the mid-span;(3)the mid-span cross-section of the girder is deformed downward,and the deformation of the side span is greater than that of the mid-span.The result shows that the 3D laser scanning technology can accurately obtain the overall spatial configuration of the bridge at a certain time,and the electronic file can be established by laser scanning technology,which can be used to assess the change of its health status with operating time and to provide technical data for comprehensive analysis of the operating status of complex structural bridge and its components.