ABSTRACT
Tunnelling through urban areas asks for a minimal ground loss. Modern TBM’s can operate at an average ground loss of 0.5% or less (Bowers & Mos, 2005). To be able to calculate the ground loss that can be expected in this range it is necessary to improve the calculation methods. One decade ago it was sufficient to calculate whether the front pressure was sufficient to prevent a collapse of the bore front and not high enough to get a blow-out. Nowadays 4-D finite element modelling is used to estimate the ground loss and the settlement trough that is the result of it.
