基于车载三维激光扫描结果的桥面变形分析

车载三维激光扫描技术能够直接对目标结构表面进行三维量测，并采用三维阵列点云的方式来生成结构物表面的三维形态和记录点位坐标，打破了传统的桥梁变形监测方法仅有数个独立点的局限性，扩大了桥面变形监测范围，提高了结构物的观测精度，并能快速、完整的进行量测。本文将车载三维激光扫描技术引入到桥梁变形监测中，基于全长331.2m的预应力混凝土连续-刚构桥为背景，采用三维激光扫描技术对其温度变形进行探索。在监测环境温差20℃范围内，对其进行多次桥面几何形态数据采集，并对采集的数据进行处理。对基于车载三维激光扫描点云数据的NURBS(Non-Uniform Rational B-Splines)曲面提出了一种新的变形测量方法，得到整个桥面的变形测量结果，再与采用有限元分析软件MIDAS CIVIL建模得到的各温差下理论变形数据进行对比，发现基于NURBS曲面的分析处理方法获得的变形测量值具有良好的精度和可靠性，并能够获取桥梁点-线-面的整体变形监测结果，与单点变形监测相比，弥补了其缺乏线性变形及整体变形特征的不足，有较好的工程应用前景。

Bridge Deck Deformation Analysis Based on Vehicle Borne Three-dimensional Laser Scanning Results

The vehicle borne three-dimensional laser scanning technology can directly measure the surface of the target structure, and use the three-dimensional array point cloud to generate the three-dimensional shape of the surface of the structure and record the coordinates of the point. This breaks the traditional bridge deformation monitoring method with only a few independent methods. The limitation of the point expands the monitoring range of bridge deck deformation, improves the observation accuracy of the structure, and enables rapid and complete measurement. In this paper, the vehicle borne three-dimensional laser scanning technology was introduced into the bridge deformation monitoring. Based on the 331.2m full-length prestressed concrete continuous-rigid bridge, the three-dimensional laser scanning technology was used to explore its temperature deformation. Within 20°C of monitoring environmental temperature difference, it carried out multiple bridge geometry data collection and processed the collected data. A new deformation measurement method based on the NURBS(Non-Uniform Rational B-Splines) surface of the vehicle borne three-dimensional laser scanning point cloud data was proposed. The deformation measurement result of the whole bridge deck is obtained, and the theoretical deformation data under the temperature difference obtained by the finite element analysis software MIDAS CIVIL is used. By comparison, it is found that the deformation measurement obtained by the NURBS surface analysis method has good precision and reliability, and can obtain the overall deformation monitoring result of the bridge point-line-surface, which makes up for the lack of linear deformation and overall deformation characteristics, compared with the single point deformation monitoring, also it has good engineering application prospects.