Disassembly of S900 Tunnel Boring Machine


The disassembly of the S900 TBM was carried out in the area in front of the last diaphragm of the Santa Lucia Tunnel – SOUTH ENTRANCE GN12 – by personnel of Pavimental and Herrenknecht.

 

 

 

 

 

 

 

Disassembly phases

The disassembly was carried out in two main phases, with the aim of optimising time on the basis of the reduced space available in the areas where the activity was carried out:

  • Main disassembly: main disassembly on the conveyor system which is only 44 metres long (it should be considered that the complete TBM, including Back up, is approximately 120 m long) with the assistance of an overhead crane with a lifting capacity of 320 tonnes;
  • Secondary disassembly: secondary disassembly of the main components in the areas surrounding the runway and works required for the transport phase.

 MAIN DISASSEMBLY

1

Disconnection of hydraulic circuits and electrical cables

2

Disassembly of tail shield in 5 segments

3

Disassembly of cutter head (4 external segments + 1 central segment)

4

Shell disassembly

5

Removal of the Drilling Bridge

6

Removal of erector + erector beam

7

Disassembly of shield segments (10 segments)

8

Cushion disassembly

9

Removal of erector cross

10

back-up translation at the end of the conveyor system

11

Disassembly Car 1 – back-up

12

Removal Car 2

13

Convey forward Car 3 + Car 4 + Car 5

14

Disassembly Car 3 – back-up

15

Removal Car 4

16

Convey forward Car 5

17

Disassembly Car 5

18

DISASSEMBLY COMPLETE

 

SECONDARY DISASSEMBLY

19

Division segments I+V tail shield

20

Disassembly Drilling Bridge

21

Disassembly erector cross

22

Disassembly Car 2

23

Disassembly Car 4

 

 

 

Preliminarily, together with the disconnection of all the electrical cables and hydraulic connections, the lifting lugs were installed by soldering, followed by magnetoscopic and ultrasound checks.

 

 

 

 

 

 

 

 

 

 

 

To move the heavier components (weighing between 50 and 320 tonnes) to the temporary storage areas surrounding the disassembly area, SPMT (self-propelled modular transporters) were used, capable of “loading” the components without the need for a mechanical crane.

 

Disassembly of the cushion

The cushion needed to be lightened (by the removal of all of the “accessory” components), bringing its overall weight down to 300 tonnes, to which the 20 tonnes of the rolling device should be added; the total weight was thus 320 tonnes, the maximum capacity of the overhead crane.

The cushion was lightened by:

  • Disassembling the 25 355 kW (1750 kg) electrical motors;
  • Disassembling the 25 reducers (1800 kg each) ;
  • Disassembling the Torque boxes (2) (11000 kg each);
  • Disassembly of the Displacement cylinders (13) (2200 kg each).

 Once the cushion was lightened:

a) the upper part of the rolling device was installed;

 

b) the cushion was removed from its location inside the shield;

 

 

 

 

 

 

 

 

 c) the lower part of the rolling device was installed and rolling carried out.

 

 

 

 

 

 

 

 

After disassembling the shielded part, the Back-up was disassembled, slowly conveying it along the conveyor system with the assistance of a dywidag bar system and pierced cylinders.

 

 

 

 

 

 

 

The steps in the disassembly process from Breakthrough on 12/06/2020 until completion:

  • 12/06/2020: demolition of the last diaphragm;
  • from 13/06/2020 to 10/07/2020: completion of the civil engineering works for the construction of the conveyor system;
  • from 11/07/2020 to 31/08/2020: transfer of the TBM onto the conveyor system, assembly of the 320 tonne overhead crane and testing;
  • from 01/09/2020 to 15/11/2020: disassembly of the TBM.