Tunnel convergence monitoring by radar interferometry

The measurement of displacements at the crown and convergence is crucial in tunnelling. In the case of restoration interventions, the need to demolish the existing lining often occurs leading to the requirement of close control and monitoring to guarantee the safety of the workmanship during the operations. During the demolition works contact sensors cannot be easily used as well as targets would need to be continuously removed and replaced. The use of radar interferometry, a completely remote sensing technique that avoids the need to place targets on the monitored scenario, seems to be a good option to overcome the limitations of traditional sensors. This paper will describe the testing of this remote monitoring technique in an existing tunnel in central Italy, detailing the characteristics of the equipment used, the installation process, the monitoring data, and evaluating the results obtained.