Monitoring ground deformation in tunnelling: Current practice in transportation tunnels

Ground deformation monitoring in tunnelling is a common means for selecting and controlling the excavation and support methods among those predicted in design, ensuring safety during tunnel excavation (including personnel safety inside the tunnel and safety of structures located at ground surface) and construction quality. This paper describes the types of ground deformation measurement often used in tunnelling, the difficulties in obtaining these measurements, the methods most commonly used for their evaluation, and the use of deformation measurements (a) in the selection of tunnel excavation and support systems and (b) in establishing early warning systems against ground collapse or damage to structures at ground surface. Examples of ground deformation monitoring and their application in tunnel design and construction are illustrated by cases from the Jubilee Line Extension of London Underground [Burland et al., 2001 [Burland, J.B., Standing, JR. and Jardine, F.M. (2001) "Building Response to Tunnelling" Case studies from construction of the Jubilee Line Extension, London. Thomas Telford publishers, London]; Mair, 2001 [Mair, R.J. (2001) "Research on tunnelling-induced ground movements and their effects on buildings-lessons from the Jubilee Line Extension", Proc. Int. Conf. on Response of Buildings to Excavation-induced Ground Movements, Imperial College, London, 17-18 July, CIRIA Special Publication 199, London, pp. 3-26], from Lines 2 and 3 of the Athens Metro (Kavvadas, 1998 [Kavvadas, M. (1998) "Analysis and performance of the NATM excavation of an underground station for the Athens Metro", Proc. 4th Int. Conf. on Case Histories in Geotechnical Engineering, St. Louis, Missouri USA, March 1998, paper No 6.11]; Kavvadas, 1999 [Kavvadas, M. (1999) "Experiences from the construction of the Athens Metro project", Proc. 12th European Conference of Soil Mechanics and Geotechnical Engineering, Amsterdam, June 1999, Invited lecture, Vol 3, pp. 1665-1676]) and from the 9-km long Kallidromo railway tunnel in Greece. In the first two examples, ground deformation monitoring aims to ensure that structures at ground surface are not harmed by the tunnelling operations. In the third case, the objective is the optimisation of temporary support requirements and early warning against potential collapse. (c) 2005 Elsevier B.V. All rights reserved.