Assembly Phase Of The S900 Tbm

The S-900 TBM was assembled in the area in front of the North entrance of the Santa Lucia Tunnel, in the worksite called CA08, by Pavimental and Herrenknecht. In order to optimize the timeframe and best use the configuration of the area, the pre-assembly of the individual trucks outside of the launch pad was studied from the start.

Pre-Assembly of the cutter head

The cutter head was assembled in a horizontal position. The central part, moved using a 400 ton gantry crane, was positioned on concrete blocks reinforced with metal beams and the petal were placed around and welded into place. A metal scaffolding was constructed all the way around the head and covered with a fireproof cover, which is vital for avoiding the thermal shocks of welding and protecting from adverse weather. Welding was carried out above the launch pad near the entrance to the Tunnel.

Assembly of the Shield – Phase 1

The main structure of the shield comprises 10 elements welded together. Assembly was carried out following a well defined sequence. The first components to be attached together were segments 5, 6, 7, 4 and 8, which form the base for the installation of the bearing. Subsequently, again using the 400 ton gantry crane, the bearing was raised, ensuring that it was kept in a vertical position, and placed inside the shield. The remaining reducers and motors were then installed. Afterwards, the erector cross was installed, which was raised from the pre-assembly position using the raising flanges and the 400 ton gantry crane, and was positioned above the shield. It was then possible to install the thrust cylinders.

After completion of the above installations, the construction of the shield was completed by assembling the missing elements in sequence, respectively numbers 3, 9, 2, 10 and 1, which were bolted on initially and then welded.

Assembly of the back-up

The back-up was assembled using the 800 ton crane. Following a pre-set sequence. First to be assembled was the drilling bridge, which was connected to truck 1 and the stairs and walkways were then installed. Next were truck 3 and truck 2, joined to each other and the latter joined to truck 1. This phase ended with the assembly of the stairs, walkways and ventilation ducts. The TBM was then pushed towards the entrance to the Tunnel to make space for the positioning of trucks 4 and 5 on the launch pad. After the back-up to truck 3 was positioned on the launch pad, the electrical, hydraulic and pneumatic circuits and foam and mortar injection systems were connected. Then came the initial phase of partial operation of the TBM, testing all of the components and circuits installed. This was followed by “pushing the machine” using the cylinders at the base of the shield, which provided the thrust towards the shells placed upside down. It was then possible to move the last two trucks onto the launch pad, no. 5 first and then no. 4. They were joined together, and the latter joined to truck 3. The last phase was the assembly of the stairs, walkways, ventilation duct and the final testing of the TBM.

Pre-assembly of the Tail

The tail was pre-assembled in a working area in front of the North entrance to the Santa Lucia Tunnel. The 5 segments constituting it were positioned vertically, using a 400 Ton crane, on a flattened structure constituted by cement blocks and metal beams. Inside it, for the welding of the various elements, a system of scaffolding was assembled covered in a fireproof canvas, to avoid the thermal shock of welding and ensuring the performance of activities in the event of bad weather. Lastly, the tail brushes were welded in place.

Pre-assembly of the back-up

This phase is that which required the most time and was realized almost entirely outside of the launch pad. Truck 5 was the first to reach the worksite directly overland from the Herrenknecht manufacturing plant. It is composed of 3 levels, mounted in succession using a 400 Ton crane. On completion of the assembly phase, the truck was moved using trailers and positioned on a structure of concrete blocks and metal beams.

Truck 4 was then assembled, which was also transferred to the worksite directly overland from the plant in Schwanau. The asymmetry of this truck made the preparation of a balancing structure necessary in order to ensure its stability. It is composed of 3 levels, mounted in succession using a 400 Ton crane.

A different procedure was necessary for truck 1. The invert slabs and segment feeder were installed in the launch pad. The first level was assembled outside the pad and then positioned on the launch pad using an 800 Ton crane. Levels 2 and 3 were then assembled in succession.

Pre-Assembly of the Bearing

On arrival at the worksite, the Bearing was placed directly onto the launch pad in a horizontal position, using a 400 ton gantry crane. The covering flanges were cleaned and some of the reducers and electrical motors installed.

Assembly of the Shield – Phase 2

After the closure of the shield, the assembly of the machine continued with the screw. Subsequently, with the tail of the shield being moved using powered trolleys and positioned at the raising point, the screw was welded to the shield, the brushes mounted and the initial filling of grease applied.

Assembly of the cutter head

The last element to be assembled was the cutter head. After the welding and removal of the scaffolding, the head was raised using a 400 ton gantry crane, placed in a vertical position and connected to the main bearing using flanges and bolts.

Assembly of the Thrust System and Conveyor Belts

After the TBM was properly placed on the launch pad, the thrust system and metal ring, acting as the initial marker for the excavation of the Santa Lucia Tunnel, were installed with the conveyor belts to transport the excavated material from the Tunnel to the storage tanks.