BOSRUCK TUNNEL, AUSTRIA-4TH TUBE: NATM TUNNELLING IN SWELLING ROCK CONDITIONS

摘要

In the autumn of 2009, the construction works were initiated for the approx. 5.5 kmrnlong 2nd tube of the Bosruck road tunnel on the A9 Pyhrn motorway in Austria. In therncourse of the more than 100-year history of tunnelling at the Bosruck, this tunnel isrnthe fourth tunnel that is being constructed in this part of the central mountain range ofrnthe Eastern European Alps. The 1st tube of the Bosruck road tunnel was constructedrnbetween 1980 and 1983. Soon after start-up, substantial damage became apparent inrnthe 1st tube of the road tunnel. It was only possible to maintain operation by meansrnof continuous and costly rehabilitation measures. In 2005 the extent of damage finallyrnled to the decision to add a second tube to the road tunnel and to carry out a generalrnrehabilitation of the existing tube of the road tunnel. The major conclusions drawn fromrnthe damages that occurred in the first tube of the road tunnel were used for the erectionrnof the 2nd tube and will be discussed in the present paper. For this new tunnel tube, itrnhas been decided to use a stiff lining concept (i.e., resistance principle) to counteractrnswelling and creeping pressures. Back analyses have been carried out to determinernheave deformations observed in the first tubes.