In early July, Lovat announced that it had been selected to provide two 3.7m diameter hard rock TBMs to drive 11km of tunnels for the Tizi Ouzou – Alger water transfer project in northern Algeria.
Cooperativa Muratori e Cementisti SpA (CMC) is the tunnelling subcontractor on the scheme to main contractor SNC-Lavalin (T&TI, February, p11). Lovat’s contract, which also covers ancillary equipment, is with CMC who will use the TBMs to excavate through ground described as “hard, compacted and very compacted blackish-grey marl with an RQD typically from 75-90% and a UCS up to 70 MPa”, at depths of up to 95m, but above the water table in all instances.
The first TBM will bore 2.3km for the Tizi Ouzou tunnel, followed by 2.6km for the Naciria tunnel. TBM 2 will bore the 1.2km Draâ-Ben-Khedda tunnel and the 4.8km Thenia tunnel. The primary lining will be expanded concrete rings installed with advance, consisting of three segments plus an invert plate. As the ring leaves the tailskin, it is expanded to fit the cut profile and blocked manually. Any lips or steps will be accounted for by the secondary lining in the form of a grouted in place concrete pipe.
The first TBM is due to be delivered on 30 September 2005, with TBM 2 following a month later.
