Using GPS and InSAR data to assess the cumulative damage of an underground utility tunnel

Underground utility tunnels have gradually become the focus of much research interest, but on the whole, that research remains concerned with three aspects, namely, seismic response, damage assessment, and seismic design. However, underground utility tunnels are also subject to crustal movement, which takes the forms of horizontal displacement, vertical subsidence, and ground tilt. Although the strain magnitude associated with such movement is small relative to that due to a destructive earthquake, the design life of an underground utility tunnel can be as much as a century, meaning that long-term cumulative damage cannot be ignored. Integrating the ideas of interdisciplinary research, we use geodetic data from the global positioning system (GPS), interferometric synthetic aperture radar (InSAR), and strain sensors to calculate the cumulative strain of shallow ground. The results show that the cumulative damage to an underground utility tunnel can be well inversed by using GPS and InSAR data. They also show that this cumulative damage forms a large proportion of the damage history of the utility tunnel, meaning that it should not be neglected in engineering practice. Not only is the present research a preliminary attempt to use geodetic data to calculate the cumulative damage to an underground utility tunnel, it also provides theoretical support for the safety design of underground utility tunnels.