ARLANDA INTERNATIONAL AIRPORT, STOCKHOLM, SWEDEN
CONSTRUCTION OF UNDERGROUND TERMINALS
Figure: The 600 meter long Intercity train station. Cavern span 23 meter. Geology: micaschist.
Construction of underground railroad tunnels and 3 terminals under Arlanda International airport started July -95 with the rock works finalized 2 years after in October -97. Contractor was swedish NCC and SIAB in a joint BOT project named "Banbrytarna". The fast rail link connects Stockholm central station to the airport with a travel time of less than 20 minutes. The high speed connection was opened for traffic in October -98.
The total amount of rock excavated was 800.000 m3 with 8 km of tunnels including 3 subway stations.
High horizontal stress
Due to low rock cover under critical terminal buildings (down to 10 meters) the excavation
was closely monitored with convergence and extensometer instruments, plus vibration monitoring.
Preinvestigations had shown relatively high horizontal stress levels (>10Mpa) which gave the
surpricing results that hardly any settlements were observed but a heave of up to 10mm
occured on the surface above the larger caverns right after excavation. This had no negative impact
on existing buildings and thus the initial rock stress increased the stability of the critical area
around the Arlanda terminals and no extra rock support were needed apart from normal rock bolts and
shotcrete.
Strong restrictions on the ground water table made it neccesary to include an extensive and systematic
grouting process. The geology consisted of massive granodiorite and softer micaschist.
Tunnel & GeoConsult was NCC's chief geologist during the 2 year construction period. The geoengineering department consisted of 4 geoengineers and one Cad operator handling at peak periods 16 construction faces.
Senior Engineering Geologist
phone: +47-918 41041