AAR-PREVENTION FOR THE WORLD'S LONGEST TUNNELS -ALPTRANSIT GOTTHARD AND LOTSCHBERG IN SWITZERLAND

摘要

The construction work for new railway tunnels through the Swiss Alps (Alptransit Gotthard and Lotschberg) with lengths of 57 km and 42 km respectively has been in progress since 1996. The world's longest tunnel, the Gotthard is expected to be in service in 2013, the Lotschberg in 2007. One issue of the projects is the reuse of the suitable excavated rock for aggregate production. The service life time requirement of 100 years for the tunnel construction led to studies of the concrete aggregates and the concrete mix design. In addition to the rock strength and petrographic analysis, the potential reactivity of the excavated rock and aggregates is continually measured with the microbar test AFNOR P18-588. This test gives a result in reasonable time (5-7 days). The concrete behaviour itself is determined by the performance test AFNOR P18-454. About 50% of the required concrete aggregates have been classified as potentially reactive in regard to AAR. Therefore precautions and measures have to be taken. The risk and prevention level for each concrete and shotcrete type will be discussed. Furthermore, the measures taken are presented. The results of the performance test are also discussed.