The benefits of InSAR monitoring during the construction of the Ceneri Base Tunnel

This paper introduces the InSAR method as an advanced tool to measure and monitor ground displacements during all phases of a tunnelling project. The monitoring was focused on the southern sector of the tunnel which was the most densely urbanized area and with a low overburden. The extensive monitoring system included both standard activities (measurements of vibration phenomena, topographical measurements from the surface, monitoring of groundwater levels, assessments of the condition of the buildings before, during and after the works) and the innovative satellite monitoring system InSAR. The area subject to satellite monitoring has a length of approx. 5.5 km and a width of 1 km, 500 m on both sides of the tunnel axis. SqueeSAR (R) information is summarized for specific areas following the progression of tunnelling. Finally, the results from the design predictive analyses, the in-situ deformations recorded during the excavation and the satellite monitoring data are discussed.