Detailed analysis based on vertical and longitudinal deformations estimated from InSAR displacement by data assimilation

Application of a SAR satellite to Structural Health Monitoring (SHM) has attracted much attention due to its high efficiency. SHM using a SAR satellite doesn’t require installation of sensors and has the capability of monitoring wide area. However, the displacement obtained by a single SAR satellite is line-of-sight displacement which is not either vertical or longitudinal displacement. Thus, it is not easy to interpret line-of-sight displacement. This paper aims to solve this problem. The objective of this paper is to estimate longitudinal and vertical displacement from line-of-sight displacement and to analyze in detail a fallen water pipe bridge. For estimation of longitudinal and vertical displacement, data assimilation is employed. As a result of data assimilation, successfully observed line-of-sight displacement is reproduced. Negative correlations between displacements at piers and temperature are observed. A year prior to the bridge collapse, anomalous displacement pattern is observed at the centre of the span. In addition, deformation caused by damage is observed.