Double Shield TBM: Continuous tunnel meters.
Double - or Telescopic - Shields unite the principles of the Gripper and the Single Shield TBM, enabling fast excavation even in varying rock formations.
Guadarrama, Spain
The two Herrenknecht Double Shields (Ø 9.51m) used for the Guadarrama tunnel in Spain (railway tunnel for high-speed trains) are among the most sophisticated TBMs used in machine excavation anywhere. Uniting two techniques - Shield and Gripper excavation. With the Gripper principle they achieve fast excavation in solid rock. The maximum weekly advance of over 200m demonstrates the high performance of these TBMs in this type of rock. The Shield principle can be used to drive safely even through geological fault zones. Excavation was successfully concluded in December 2004 and June 2005 respectively.
S-286 and S-296
Le Perthus, Spain
Two Herrenknecht Double Shield TBMs are being used for the construction of the Spanish high-speed rail link from Figueras in Cataluna to Perpignan in France, transversing the Pyrenees. The two tunnel boring machines (Ø 9,900mm) are excavating two tunnels of 8,230m length each through granite, gneis, granodioride and schist. The two identical Double Shield TBMs commissioned by Dragados and Eiffage started going underground in August (S-286) and October (S-296) 2005 respectively at the Spanish portal. Ca. 60% of the project had been concluded in February 2007.
