ABSTRACT
Safety is one of the crucial aspects considered in the conception of long railway tunnels. The present paper focuses on the design issues related to the construction of the emergency stops under high overburden planned for the 64 km long Brenner Base Tunnel (BBT). The project consists of two main tunnels, an exploratory tunnel and four adits.
The operational safety plan of the BBT includes the construction of cross-passages located every 333 m and 3 emergency stops spaced about 20 km. Cross-passages represent an escape route in case of emergency; emergency stops are connected to the external adits and allow the intervention of emergency vehicles and the extraction of smokes in case of fire.
The emergency stop of Trens consists in a 470 m long central tunnel connected to the main tunnels every 90 m. The overburden at the location of the emergency stop amounts to about 1100 m. The geology forecasted in the emergency stop area, mainly consists in Schist and, to a lower extent, dolomites, phyllites, quartzite, marls, serpentinites and anhydrites. In addition, two faults system are expected.
The main design challenges are represented by the complex interaction between underground structures located at 2 different elevations in combination with the high overburden and medium-low strength rock mass. The design involved high-end 2D and 3D analyses and included, in addition to the stress induced loading, swelling and creep.
