Abstract
Temperature variation plays a significant role in the long-term structural behaviour of civil infrastructures, but very few quantitative studies have measured and analysed the infrastructures’ global thermal dilation because of their large sizes and geometric complexities. The modern Differential Synthetic Aperture Radar Interferometry (DInSAR) technique has great potential in applications of their thermal dilation mapping and characterization due to the techniques’ unique capabilities for use in large areas, with high-resolution, and at low-costs for deformation measurements. However, the practical application of DInSAR in thermal dilation estimation is limited by difficulty in the precise separation from the residual topographic phase and the trend deformation phase. Moreover, due to a lack of thermal dilation characteristics analyses in previous studies, the thermal dilation mechanisms are still unclear to users, which restricts the accurate understanding of the thermal dilation evolution process. Given the above challenges, an advanced multi-temporal DInSAR approach is proposed in this study, and the effectiveness of this approach was presented using three cases studies concerning different infrastructure types. In this method, the coherent, incoherent, and semantic information of structures were combined in order to refine the detection of point-like targets (PTs). Interferometric subsets with small temporal baselines and temperature differences were used for high-resolution topography estimation. A pre-analysis was adopted to determine the transmission direction, spatial pattern, and temporal variation of the thermal dilation. Then, both the traditional least squares estimation and our robust coherence-weighted least squares regression analysis were performed between the time series displacements and the corresponding temperatures to quantitatively estimate the thermal dilation model. The results were verified in terms of the estimated linear thermal dilation coefficient, which indicates the greater reliability of our method. Furthermore, the thermal dilation characteristics of different civil infrastructure types were analysed, which facilitates a greater understanding of the thermal dilation evolution process of civil infrastructures.
Highlights
The widespread deterioration and the inadequate upkeep of existing civil infrastructures, such as buildings, highways, and bridges, has accelerated the growing costs of their replacements and repairs, and brought significant risks to public safety and quality of life [1,2]
The coherent and incoherent information derived from the high-resolution SAR images, as well as the detailed semantic information about specific structures are fully integrated into the multi-temporal Differential Interferometry Synthetic Aperture Radar (DInSAR) processing to refine detection of point-like targets (PTs)
Given the advantages of richer ground target information and a higher sensitivity to the small deformations in the high-resolution SAR images, a multi-temporal DInSAR approach, which estimates the civil infrastructure thermal dilations with an increasing number of PTs and high-resolution topography estimation based on TerraSAR-X images, was applied in this study
Summary
The widespread deterioration and the inadequate upkeep of existing civil infrastructures, such as buildings, highways, and bridges, has accelerated the growing costs of their replacements and repairs, and brought significant risks to public safety and quality of life [1,2]. To ensure the safe operations of these infrastructures and to reduce the maintenance costs, the consecutive stability monitoring of such manmade structures in an economical manner is important, especially in densely inhabited areas, to detect the deformation at an early stage and to prevent the associated risks by taking timely measures [3,4]. It is difficult to achieve this goal using current in situ methods for civil infrastructure monitoring because most in situ techniques (e.g., leveling and total station surveys) are labour-intensive and not frequently performed [5,6]. The short wavelength of 3.1 cm, short revisit cycles, and high resolution of 3 m in Stripmap mode considerably distinguishes this data from previous civil SAR systems, enabling the detailed monitoring of civil infrastructures [18,19,20,21,22,23,24,25]
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