ABSTRACT
The current trend of today’s planned infrastructure projects especially in the inner city areas are tunnels with large tunnel cross sections. The owners and planners quite frequently plan tunnels with diameters larger than 10 meters. For very large diameter tunnel boring machines the German machine manufacturer Herrenknecht has extensive and most varied references with regard to varying geological conditions like soft rock, hard rock and mixed face conditions with high groundwater pressures. Mechanised Tunnelling with diameters up to 16 meters can be reliably controlled and are faster than conventional tunnel construction. It is more limited by the handling logistics, such as transportation of excavated material, than by questions relating to construction safety and economy. Outstanding references such as the pioneering Mixshields (Ø15.43 m) for Shanghai and the Earth Pressure Balance Shield (Ø15.20 m) for the M30 Project in Madrid show the feasibility of handling large tunnel cross sections with successful and safe tunnelling technology. This paper is to highlight the machine technology and optimization possibilities for upcoming large diameter projects. After an overview on Tunconstruct activities, recent and upcoming large diameter TBM projects are presented.
