Comparative Analysis of Single-Point and Overall Monitoring of Settlements in Embankment Expansion: An Application Case Study of 3D Laser Scanning Technology.

At present, the single-point observation method is not able to effectively monitor the overall settlement of the target surface of an embankment. The 3D laser scanning technology was, therefore, introduced to help solve this problem. In this study, the overall settlement of the Shi'an highway extended embankments were dynamically monitored and a series of point cloud data were obtained by 3D laser scanning. Due to the characteristics of point cloud data, the grid analysis and interpolation method in MATLAB were proposed for the analysis, so as to obtain the overall settlement displacements of the extension embankment. Furthermore, the reliability and accuracy of the 3D laser scanning were verified through comparison with the single-point observation, and the results are as follows: during the embankment extension construction process, the monitoring accuracy was improved by 25.8% at least when compared to the single-point observation method; during the asphalt pavement construction, the maximum settlement of single-point monitoring and the 3D laser scanning method recorded similar values of 1.6 mm and less than 2 mm, respectively; throughout the course of the 3-year post-construction settlement observation, the monthly settlement rate was maintained at an insignificant 0.01-0.09 mm/month for the single-point monitoring, and a similar rate of less than 0.05 mm for the 3D laser scanning method. These results show that the 3D laser scanning could reflect the overall settlement dynamics much better, and that combined with its advantages of fast and accurate observation, could be used to evaluate the settlements of new and old embankments in extension projects. [ABSTRACT FROM AUTHOR]