拱坝有限元模型动力参数视频测量识别方法

Dynamic Parameters Identification of an Arch Dam Finite Element Model Using Video Measurement

针对传统接触式传感器在大坝动力测试中存在的安装困难、布置稀疏等问题,首次提出通过基于相位的视频测量方法实现大坝动力参数的快速识别.以国内某拱坝为工程背景,基于Abaqus有限元分析平台建立了大坝-地基三维模型,模拟了环境激励下大坝振动响应过程并导出坝顶运动视频.采用基于相位的视频运动估计方法提取坝顶的微小运动信息并识别其固有频率,通过运动放大技术获取不同固有频率下坝顶的运动放大视频,利用直方图阈值分割法获取量化的坝顶工作变形.与拱坝有限元模态分析结果对比表明:视频测量方法可以准确识别拱坝模型固有频率及工作变形,同时采用阈值分割法可以从放大视频中准确量化坝顶工作变形.

Aiming at the problems of difficulty in installation and sparse arrangement of traditional contact sensors in the dynamic testing of dams,the phase-based video measurement is employed to realize the rapid identification of the dam dynamic parameters for the first time.Based on the ABAQUS finite element analysis platform,a three-dimensional dam-foundation model was established for an arch dam in China.The vibration response process of the arch dam under environmental excitation was simulated and the motion video of the dam crest was derived.The phase-based motion estimation method was used to extract the micro-motion information of the dam crest and identify its natural frequencies.The motion-magnified video of the dam crest under different natural frequencies was obtained using the phase-based motion magnification,and the quantified operational deflection shapes(ODS)of the dam crest were identified using the image threshold segmentation.Compared with the results of finite element modal analysis,the phase-based video measurement can accurately identify the dynamic parameters of the arch dam model.In addition,the threshold segmentation method can accurately quantify the ODS’s of the arch dam crest from magnified videos.