ABSTRACT
Since the route of the Gotthard Base Tunnel (GBT) was decided, it has been known that in the Sedrun section two constructional difficult zones – the Tavetsch Intermediate Massif (TIM) (North) and the Urseren Garvera Zone (UGZ) – must be cut through. In both zones, squeezing rock conditions are expected to be encountered. The main questions during design and construction are:
1. With what type of ground conditions are we confronted?
