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Abstract: The 13km-long safety tunnel of the existing Frejus Highway Tunnel at the French-Italian border, in the Western Alps, is currently under construction. The first 6.5-km lot is successfully excavated. The tunnel is being excavated by a 9.4m-diameter, single shield TBM and is lined with 0.4m-thick precast concrete rings. The tunnel is excavated through anisotropic schistose...