Assessment of Railroad Residual Settlement Zone Based on D-InSAR and Field Measurements

Several sections of concrete tracks for high-speed rails in Rep. of Korea are being treated using various techniques to control residual settlement. The cause of residual settlement is due to not only soft ground condition, but also inadequate compaction quality control of substructure. In this study, field tests using standard penetration test (SPT) and dynamic cone penetration test (DCPT) along the sections exceeding allowable settlement requirement were conducted to evaluate bearing capacity of substructure. The results of field penetration tests were used to establish input data of a numerical analysis to predict residual settlement of the tested section, which was then compared to the measured settlement along the test period. In addition, an attempt was made to employ D-InSAR techniques to estimate residual settlement of the corresponding sections over a two-year period. The results of the penetration test exhibited reduced load bearing capacity of substructure, and the predictions of numerical analysis were compatible with field settlement measurement. The application of D-InSAR technique has shown to be promising in estimating ground settlement along the concrete track over time, and the estimation of D-InSAR could be enhanced through image data processing.