Tunnel complex unloaded by a deep excavation

This paper examines the effect of a deep open excavation for an office block on the underlying tunnel complex in the centre of Prague, which was analysed using 2D FEM models. In order to get a proper reference state before excavation, the whole process of construction of the tunnels was modelled and deformation and stress changes induced by open excavation predicted. Bearing capacity, distortion and watertightness of underground structures were then evaluated and recommendations concerning the construction rate and monitoring program given. A good agreement between the pure prediction of tunnel distortion produced by FEM and the measurements undertaken during excavation of the pit and construction of the office block was obtained. (C) 2001 Elsevier Science Ltd. All rights reserved.