Seasonal deformation features on Qinghai-Tibet railway observed using time-series InSAR technique with high-resolution TerraSAR-X images

Abstract

Climate change and human activity are changing the dynamics of the Qinghai-Tibet Plateau (QTP) environmental balance, which impacts the safety and stability of its infrastructure. The Qinghai-Tibet Railway (QTR) is the longest structure in the QTP, and some sections of the QTR’s embankment have been damaged due to freezing and thawing of permafrost. In this article, a modified SAR interferometry (InSAR) method for deformation monitoring is proposed and implemented. In this method, a seasonal deformation model based on the simplified Stefan equation has been adopted to measure the seasonal displacement. In particular, a linked coherence model is used to improve the effect of temporal correlation by defining a coherence parameter in the neighbouring pixel network. It was found that most of the study area had seasonal displacements of up to 20 mm. The deformation cross-section profile of the railway shows asymmetry between the two sides of the railway subgrade shoulders which may be related to sunny-shady slope effect. It was found that variable deformation along the QTR ranges from 0 to 30 mm, probably due to underlying permafrost conditions. Displacements of the experimental railway subgrade segment with varying types of cooling measurements are different, which shows their cooling efficiency variance.