Ground surface settlements due to underground works

Ground surface deformations due to tunneling are crucial in urban regions where damages to surface structures and utilities should be prevented. In this paper the detection and monitoring of the vertical displacements of an area situated above the axis of one of the Athens METRO tunnels, where damages on constructions were observed during the excavations, is presented. For this purpose a geodetic vertical control network is established (March 2003). The features of the network, especially those regarding its sensitivity and reliability are presented. Significant displacements ranging up to 96 mm were detected from the comparison of the adjusted heights of the network's points against those of the reference epoch to before the beginning of the underground works. Finally the conclusions withdrawn are presented.