Prediction Method of Tunnel Longitudinal Settlement under Surface Overload Based on PS-InSAR

The overload on the ground surface causes the longitudinally uneven settlement of tunnels and endangers the safety of tunnel operations. The settlement monitoring data of tunnels plays a significant role in analyzing the safety of the tunnels. A method of tunnel settlement prediction based on Persistent Scatterer Interferometric Synthetic Aperture Radar (PS-InSAR) under ground surface overload is proposed. The method is applied in the Shanghai Yanggaozhong Road power tunnel project. The results show that: PS-InSAR technology can be applied to collect high-accuracy ground settlement data with an average error of 0.78mm/y compared with ground-level monitoring data. The tunnel settlement rate curve predicted by this method is relatively consistent with the tunnel level measured curve, and the location of the longitudinally uneven settlement of the tunnel is detected accurately. Compared to the measured settlement rate of the tunnel, the average error of predicted settlement rate for the tunnel is 3.09mm/y. The main factors affecting the accuracy of the results include the fitting error of ground surface settlement caused by using PS-InSAR data, the settlement calculation error of soil layers above the tunnel, and the soil disturbance caused by the construction activities in the vicinity of the tunnel. PS-InSAR shows such advantages as the wide range of monitoring and the access to historical data, which contributes new ideas to the acquisition and analysis of tunnel settlement data in soft soil areas.