Subsidence Monitoring and Factors Analysis of Beijing-Tianjin High-speed Railway Based on InSar

Abstract

Beijing-Tianjin Intercity Railway is the first high-speed railway in China. It is an important part of the inter-city railway transit network in the Bohai Rim. High-speed railway has the requirements of high smoothness and high stability to the subgrade. However, in recent years, due to the development of the city, ground subsidence caused by overexploitation of groundwater has caused serious threat to the safe operation of high-speed railway. Therefore, it is significant to conduct continuous observation and analysis for the deformation of high-speed railway and the environment along it.In this paper, TerraSAR-X data is mainly used to study the Beijing Tianjin inter-city railway（Beijing section）, and the Interferometric point targets analysis (IPTA) technique is applied to process the SAR data, so as to accurately estimate the ground deformation in this region. In addition, the results are verified by combining with the second-level leveling results in the range of the region, and the results obtained by this method have a better estimation of the deformation.The Maximal Information-based Nonparametric Exploration method is used to explore the relationship between the various influencing factors and the deformation of high-speed railway. The reasons of uneven settlement along the high-speed railway are analyzed synthetically by combining the results of deformation with the data of groundwater, geological strata, fault zone, aquifer system and precipitation in the area. This method can quantitatively describe the relationship between the above factors and the settlement point, more intuitive understanding its impact on the settlement of high-speed railway. The results show that during the observation period, serious spatiotemporal non-uniform settlement of the high-speed railway has occurred along it. Then the results of InSAR time series deformation and second-level leveling results are combined, the time series segmentation characteristics of deformation point is studied. Ground subsidence and the decrease of groundwater level has a better response. The increase of the groundwater exploitation quantity, resulting in the decrease of underground water level, leading to the settlement of the area increased. At the same time, the land subsidence has a certain relationship with the compressible layer thickness in this area. Through statistical analysis, the correlation between settlement and various factors are summed up to determine the key areas for settlement monitoring. Provide important decision support for the safe operation of high-speed railway.