大坝一等水平位移监测网数据处理流程及精度保障措施

Comparative Analysis of 3D Laser Scanning and Nap-of-the-Object Photogrammetry in Slope Protection Networks Measurement

大坝水平位移监测网是大坝变形监测的平面基准,监测网的精度关系大坝变形监测结果的可靠性和大坝安全鉴定结论的正确性。为了提高监测网数据处理精度,依托大型水电站大坝监测网复测项目,研究分析相对湿度、斜距化平方法、地球曲率半径对边长改化的影响。结果表明:相对湿度修正对边长的影响值最大可达2 ppm,斜距化平时采用高差计算的边长比采用垂直角计算的边长精度高0.05~1.95 ppm,用测区地球平均曲率半径代替测距边法截线地球曲率半径对投影边长的影响值最大可达0.08 ppm;高精度大坝水平位移监测网数据处理时,应用相对湿度修正实测边长,优先选用高差斜距化平,可用测区地球平均曲率半径代替测距边法截线地球曲率半径。研究成果可为类似项目提供有益参考。

The horizontal displacement monitoring network of dams is the plane benchmark for dam deformation monitoring.The reliability of the dam deformation monitoring results and the conclusion of the dam safety evaluation are subject to the precision of the monitoring network.In order to improve the data processing accuracy of the monitoring network,relying on the re-survey of the dam monitoring network of large-scale hydropower stations,the influence of relative humidity,slope distance flattening method,and earth curvature radius on the modification of side length is studied and analyzed.The results show that the maximum influence of relative humidity correction on side length can reach 2 ppm,the side length calculated by height difference in slope distance flattening is 0.05~1.95 ppm higher than the side length calculated by vertical angle,and the maximum influence of using the average curvature radius of the earth in the survey area instead of the earth curvature radius of the normal section line at the distance measurement side on the projected side length can reach 0.08 ppm;when processing the data of the high-precision monitoring network for dam horizontal displacement,relative humidity should be used to correct the measured side length,and the slope distance flattening of height difference shall be adopted.The average curvature radius of the earth in the survey area can be used instead of the earth curvature radius of the normal section line at the distance measurement side.The study results can provide reference for similar projects.