The number of aging civil engineering structures is rapidly increasing in Japan. As for dams, it is estimated that in the year 2020, 58% of existing dams will be 50 years or more since completion. This situation increasingly requires not only efficient deformation monitoring systems for safety management of civil engineering structures but also safe and rapid methods in case of emergencies such as earthquakes.

Remote sensing techniques, especially Synthetic Aperture Radar (SAR), can play an important role to conduct deformation monitoring of civil engineering structures such as dams and rock slopes. Differential Interferometric SAR (DInSAR) analysis using SAR satellite data can be suitable for deformation monitoring over wide areas.

To examine the applicability of DInSAR analysis for deformation monitoring, a rockfill dam with a center core with a height of 66m is selected as a study area because deformation monitoring using GPS has been rigorously conducted since the completion of the dam in December 2006.

The values of deformations calculated by DInSAR analysis are about 70 or 80% of those measured by GPS during the observation period of about four years. Although the DInSAR analysis results are expected to have some errors and are different from the GPS measurement results to some extent, DInSAR analysis is sufficient to monitor few-centimeter deformations. Additionally, the settlement and subsidence trends of the dam can be well reproduced utilizing time series changes by DInSAR analysis. This indicates potential for DInSAR analysis to be used for deformation monitoring of civil engineering structures and rock slopes.

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