Development of a novel tunnel dismantling machine for the MTR West Island Line construction

ABSTRACT

The MTR West Island Line (WIL) Contract No. 703 from the Sheung Wan Station (SHW) tunnel to the Sai Ying Pun Station (SYP) tunnel is part of the extension of the existing MTR Island Line (ISL) of Hong Kong Island. The project involved the demolition and backfilling of 132 m of the existing Overrun Tunnel (ORT) through complex geology beneath a densely-populated urban area in order to enable the subsequent excavation of the WIL Down-track (westbound) running tunnel using a tunnel boring machine (TBM). The innovation of a bespoke tunnel dismantling machine (TDM) to tackle this challenge was adopted to minimise construction risks. A concrete bulkhead was built to separate the TDM works area from the operational railway. The TDM worked backwards from the operating railway interface inside the ORT to remove each ring of lining segments under 2.8 bar compressed air pressure, placing a sprayed concrete lining for temporary support and backfill of the remaining void left underground. The crew behind the demolition chamber of the TDM remained at atmospheric pressure. Part of the backfilled tunnel was then re-excavated by slurry TBM to form the realigned WIL Down-track running tunnel. The TDM is unprecedented globally and accomplished the works safely, successfully leading to the opening of the WIL. This paper explicates the TDM’s development with the design and construction aspects of the tunnel dismantling works.

KEYWORDS:

• Confinement
• hyperbaric intervention
• lining segment
• shotcrete
• tunnel dismantling machine
• tunnelling

Acknowledgement

The authors would like to thank MTR Corporation for giving permission to publish this paper.

Additional information

Notes on contributors

P L Ng

Ir Dr P L Ng was a Deputy Construction Manager at Dragages-Maeda-BSG Joint Venture and has been involved in major civil infrastructure projects such as Hong Kong West Drainage Tunnel, Tuen Mun-Chek Lap Kok Link, and MTR West Island Line Sheung Wan Station to Sai Ying Pun Station Tunnels. He obtained his Bachelor of Civil Engineering and Doctor of Philosophy degrees at The University of Hong Kong. He is an Honorary Secretary and a Fellow Member of the Hong Kong Concrete Institute, and a research fellow of the Hong Kong Road Research Laboratory. He has published more than 100 technical papers and has delivered more than 50 technical speeches in the areas of concrete science, civil structures, and construction technology. He is a registered civil engineer in Hong Kong and the UK, and an accredited BEAM Professional by The Hong Kong Green Building Council. He has been awarded Sir Edward Youde Memorial Fellowship in 2005, The HKIE Outstanding Paper Award for Young Engineers/Researchers by The Hong Kong Institution of Engineers in 2012, Certificate of Merit, the HKIE Innovation Awards for Young Members in 2013 and 2017, and Marie Skłodowska-Curie Actions Fellowship by the European Commission in 2017.

S Polycarpe

Mr S Polycarpe has over 27 years of post-qualification worldwide and multi-disciplinary experience in tunnel construction, beginning with the Channel Tunnel and including 18 years working with TBMs, covering the variety of air plenum, earth pressure balance (EPB) and slurry mix shield machines, as well as hard rock machines. His soft and hard ground tunnelling experience includes canopy vault and grouting, timber headings, the new Austrian tunnelling method (NATM), ground freezing, drill and blast, and tunnel dismantling machines. In 2009, Mr Polycarpe joined the Dragages Hong Kong Ltd as the Technical Manager for MTR West Island Line Contract No. 703 and since 2012, he has been working as the Head of Engineering Department for the Dragages-Bouygues Joint Venture for the Tuen Mun–Chek Lap Kok Link Northern Connection Sub-sea Tunnel project.

T N D R Barrett

Eur Ing T N D R Barrett has over 17 years’ experience both with contractors and clients in the construction industry, predominantly in complex underground construction around the world. He started his career in the mining and quarrying industries with Rio Tinto and Hanson Aggregates and then moved into heavy civil tunnelling works, initially with J Murphy and Sons in the UK. Over the last seven years, he has been working in Hong Kong for the MTRC as a Construction Manager and Engineer's Representative on the West Island Line and Shatin to Central Link projects, as well as on several pedestrian subway projects such as the Club Street Subway.

G Roux

Mr G Roux has been working for 10 years with CSM Bessac, a tunnelling specialised subsidiary of Soletanche Bachy, part of the Vinci Group. He has been working on projects on different continents involving a wide spectrum of underground techniques, including pipe jacking (sea outfall in Morocco), EPB TBMs (Interceptor Tunjuelo Bajo in Colombia, Oued M’Kacel Sewer in Algeria), ground freezing (MTR West Island Line Contract No. 703 in Hong Kong), slurry mix shield TBMs (Norris Cut Tunnel in Miami, the US) and air boom shields (Sila Sewer in Annecy, France). In the MTR West Island Line contract in Hong Kong, he was in charge of the tunnel dismantling operation under challenging conditions by employing the specially designed tunnel dismantling machine.

F Vallon

Eur Ing F Vallon has over 30 years’ experience in methods planning and estimating of infrastructure projects. He started his engineering career with Bouygues Travaux Publics in France, first in the building department and then in the technical division of the civil works department in 1994, and he is now principally in charge of methods planning and estimating of mechanised tunnel projects.