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PORTUGAL: 1st Raise Boring completed in power reinforcement at Venda Nova III Dam

29 July 2011 No Comment

Raise Boring processThe first of seven Raise Boring operations (drilling construction process) planned for reinforcing the power of Venda Nova III dam is completed. Aiming at the construction of the upper surge shaft, the process was to dig previously the tunnel and the expansion chamber. The execution of the pre-containment ring, from which it was possible to install the Raise Boring equipment, was simultaneously carried out at the surface. Then began the execution of pilot hole (11″ diameter) down to the expansion chamber, at 63 m below the ground, where a 2.44 m diameter reamer head is placed for the further reaming operation  (digging upwards), creating a pit that allows the debris resulting from the excavation, currently in progress, is collected in the gallery below through the traditional method. The final section of this pit (chimney) will have a diameter of 13 m. It should be noted that the civil construction works of the new hydropower station are carried out by Mota-Engil Engenharia in a joint venture with MSF, Somague and Spie Batignolles.