Robbins TBM to Excavate Venaus Exploratory Tunnel on Lyon-Turin HSLA Robbins high performance open type hard rock TBM will be used by the CMC-led JV including Strabag, Bentini Costruzioni, Cogeis and Geotecna for the Venaus exploratory tunnel on the Lyon-Turin high speed line across the Alps between France and Italy. The nominal diameter is 6.3 m. The cutterhead will be equipped with 41 17" cutting tools. The 380-ton TBM is 35 m long (200 m with the back-up) and is characterised by a 3,720 kW installed power, 10,250 kN nominal thrust (14,200 kN maximum), 2 x 16,370 kN thrust force of gripper cylinders, 0-11.4 rpm rotating speed, 7x 315 kW installed main drive power, 4,066 KNm breakout torque and four thrust cylinders.The tunnel alignment spans 7 km in Italy, with option for three more kilometres on the French territory. From the 1.2 kilometre line, the cover exceeds 400 m and even reaches 1,000 m after 6 km. The section in option has an average cover of 2 km. The pilot tunnel will cross the Ambin crystalline bedrock and metamorphic layers. The geology is composed by schists, gneiss and mica schists. Between the 0.9 and 1.4 kilometre lines, carboniferous breccia (carnelian formation) will be crossed. It is particularly critical due to geomechanical characteristics with falling rock in the presence of water. High rock temperatures (up to 50°C) are also expected where the cover is the highest. A 350 cu m/h conveyor belt will be used for mucking out. Support will be ensured with bolts (Swellex type) or sheet plates (0.4 to 1.4 m in width with HEB120 and IPE120 steel beams) spaced out at 0.8 to 1.4 m and welded mesh. The TBM is scheduled to be delivered in November 2005 for tunnelling start in January 2006. Click it/80. Visit www.robbinstbm.com, www.cmcra.com and www.strabag.it 22/05.