###### Abstract  
Safety assessment must accurately grasp deformation information of a high-speed railway bridge. When the ground-based radar collected high-frequency data, white and colored noises will be present in the radar signal due to the influence of environment and instrument errors. The existence of the above-mentioned two kinds of noises will affect the accurate estimation of deformation information. Based on the above situation, a ground-based real aperture radar (GB-RAR) deformation information estimation method considering the effect of colored noise was proposed in this work. The proposed method was applied to the safety monitoring and analysis of East Lake High-tech Bridge during the Wuhan Metro Line 11 shield tunnel crossing underneath this bridge. First, the settlement deformation time series of the bridge was derived based on GB-RAR, and it was verified by leveling at an accuracy better than 0.27 mm. Second, white, and colored noises were detected in the denoised settlement deformation time series through a power spectral analysis and maximum likelihood estimation, and the colored noise spectral indexes were approximately \(-1\). Finally, according to the proposed method, the estimated settlement rates of No. 7 and 8 piers were 0.0112 \(\pm\) 0.0026 and \(-\)0.0046 \(\pm\) 0.0053 mm/h, and the accumulative settlement values were \(-\)0.40 and \(-\)0.16 mm, respectively. The results were in good agreement with the results of leveling measurement and more accurate than those of the deformation information estimation method without considering the effect of colored noise. The research results showed the reliability and effectiveness of the method in this work, and the bridge was stable and safe during the monitoring period. GB-RAR; high-speed railway bridge; deformation information; colored noise +
Footnote †: journal: Applied Sciences  
to monitor the Radotin Bridge in Prague, Czech Republic, and obtained the displacement. [PERSON] et al. [20] proposed a structure knowledge-InSAR integration method. The method has been successfully applied to high-precision deformation monitoring and risk identification of sea-crossing bridges. [PERSON] et al. [21] used time-series methods to post-process the PS-InSAR-derived time-series displacements of the Hong Kong-Zhuhai-Macao Bridge based on Sentinel-1A TOPS SAR images spanning from 2018 to 2020. The results showed that the continuous subsidence of about 17 mm/year were detected at the east man-made island. The InSAR technology can overcome the limitations of traditional deformation monitoring methods because of its advantages of non-contact, high spatial resolution, and low cost [22; 23; 24; 25]. However, high precision dynamic deformation monitoring of bridges is difficult to achieve due to the limitations of InSAR technology satellite platform (such as low time resolution and geometric distortion) [26; 27]. To overcome the disadvantages of InSAR, a ground-based radar interferometry technique was proposed, which can monitor a small line of sight deformation of the monitored object within a few thousand meters from the real time radar sensor (about 0.01 mm) [28; 29; 30]. Based on the different imaging principles and systems of ground-based radar, ground-based radars are divided into two types: ground-based real aperture radar (GB-RAR) and ground-based synthetic aperture radar (GB-SAR). The GB-RAR technology has the advantages of high precision measurement, high data sampling frequency, and simultaneous response at multiple points [31; 32; 33]. According to the monitoring requirements, the most favorable monitoring orientation can be selected for the bridge to be monitored to install the ground-based interference radar [34; 35]. Since the GB-RAR technology was put forward, it is widely used in bridge deformation monitoring and analysis. [PERSON] et al. [36] analyzed the dynamic characteristics of Italy's Musmeci bridge by GB-RAR and verified it with accelerometer and microseismometer data. The results of the three technologies showed high consistency. [PERSON] et al.