1. The Tunnel Dismantling Machine (TDM)
Hong Kong Island Line Metro Extension Case Study

2. Topics Covered Project Overview Solution to Technical Challenges
Extension Tunnel Alignment
Tunnel Clash
What is a TDM?... and how does it work?
Structure of the TDM
Typical Stages of Operation
A Short video
Awards

3. Project Overview Client: MTR Corporation (Hong Kong Metro)
Project: Hong Kong Island Line metro extension
Contract: West Island Line – Contract 703
Contractors: JV Maeda Corporation Hong Kong , Bachy Soletanche and Dragages Hong Kong
Scope of Works:
Four ØID 5.30m tunnels (3300m combined Slurry TBM & D&B)
Three mined stations (D&B)
Technical Challenge and Conditions:
Interface between old and new infrastructure
Connection of new tunnels with existing network at Sai Ying Pun station – Initial works require removal of 137m segmentally lined overrun tunnels that clash with the updated alignment
Densely populated urban area
Limited worksite space on surface – Sensitive stakeholders
Poor ground conditions – mainly decomposed granite, marine soils and fill material under high hydrostatic load in the bay area

4. Solution to Technical Challenges
Use of TBMs for main drives
However incompatible with in existing lining in-situ
Launch and reception of TBMs in mined caverns
Innovative use of a TDM (Tunnel Dismantling Machine)
Deconstruction work carried out using compressed air technology
Designed and constructed by CSM BESSAC, of France

5. Location of overrun tunnel
Extension Tunnel Alignment
Location of overrun tunnel
Constructability Issue:
Where do you put your construction site?

6. Tunnel Clash

7. What is a TDM?...
…and how does it work?

8. Structure of the TDM

9. Typical Stages of Operation
Seal the section of tunnel to be deconstructed by creating a bulkhead structure (Under hydrostatic load conditions)
Preparatory grouting work around the annulus of the tunnel in locations that are identified as likely to give rise to complications.
Removal of track and cast invert
Installation of the TDM at the bulkhead end of the overrun tunnel
Removal of tunnel rings, segment by segment under 2.8bar pressure
Installation of shotcrete coat to stabilise excavation during temporary load case
After each 2m advance, installation of lean concrete backfill
Re-excavate the new tunnel alignment using slurry TBM.

10. A Short video

11. Final stage of enabling works after removal of TDM

12. Awards
The TDM design used to dismantled tunnels in Hong Kong, receives four innovation Awards:
“Product or Equipment Innovation of the Year Award (2013)” awarded by the ITA (International Tunnelling Association)
“Trophies of Public Works” (Process / Materials category), awarded at the FNTP awards
“Special Award for the Technical Mastery” awarded at the VINCI Innovation Awards
“Solétanche Bachy and Menard Grand Prix” awarded during the SoilTeam agreement on Wednesday, October 16th in Geneva

13. References TDM Video: https://www.youtube.com/watch?v=EtsADqc175o
Vallon, F. et al. 'Tunnel Dismantling Machine – From Innovation To Completion'. World Tunnel Congress 2013 Geneva Underground – The Way To The Future!. London: Taylor & Francis Group, Print.
TDM Video:
TDM Manufacturer:
Contractor Information:
Project Information:
Client Promoter Information:

14. Tunnel demolition can be done safely and cost effectively!
It works!
Tunnel demolition can be done safely and cost effectively!
To conclude

15. Thank you for listening!
Any questions?
Thank you for listening!