THE KOWLOON CANTON RAILWAY COMPANY

The Kowloon Canton Railway Corp is one of the largest railway operators in the world, transporting more than one million passengers daily.

To cater for increasing population movements between the residential areas in the New Territories and the business centres of Hong Kong and Kowloon, KCRC is extending its transport network.

The largely urban nature of Hong Kong, together with the mountainous terrain, mean that tunnels become an essential component of virtually any infrastructure project.

At $8bn, KCRC's West Rail project is Hong Kong's largest single infrastructure investment.

Contract DB320, awarded to the Dragages/ Zen Pacific JV is part of Stage 1 of the project and includes the boring of the Kwai Tsing Tunnel between the stations of Tsuen Wan West and Mei Foo.

Instead of using conventional drill and blast and cut and cover methods, the JV recommended using a Tunnel Boring Machine (TBM) to drive two parallel 2km tubes for the Tsin Tsuen Tunnel sections.

This would minimise impact on the urban environment and overcome problems presented by the difficult geology. Driveage was to be through terrain with significant faults under an extensive water table and some 70 m of difficult soft ground. The TBM would eliminate the need for risky and costly, time consuming protective measures.

NFM Technologies of Lyon, France was asked to design an Earth Pressure Balance TBM to cope with complicated strata. The geology ranges from soft alluvial marine sands and clays containing boulder rock, solid granite with a UCS strength of 80 to 250 Mpa and mixed conditions in between.

NFM designed and built a hybrid TBM capable of operating in both open and closed modes with a choice of screw and belt conveyor for mucking out.

The two conveyors are permanently installed within the shield and conversion from one to the other can be effected within five man-shifts. Containment is either by compressed air or earth pressure.

The drive system includes nine variable speed ( 0-3 rpm ) 250KW electric motors with frequency converters.

The maximum breakout torque is 17,750kN and total thrust 66,000kN.

The shield assemble comprises articulation, stabilisers and grippers. In compliance with safety regulations, three personal airlocks and two material airlocks are installed to facilitate maintenance and the change of tools and cutter discs.

State-of-the-art fluid systems handle foam, mortar, bentonite and tail seal grease injections.

The TBM incorporates an automated erector with an 8 tonne capacity vacuum segment handling system capable of installing a full ring within 20 minutes.

From his roomy, comfortable control room, the pilot can operate the TBM thanks to comprehensive information network collecting automatically up to 80 parameters.

The tunnel lining is 400mm thick, 1.8m reinforced pre-cast concrete segments and the tunnel profile has gradient up to 4 %.

Named MULAN, NFM's TBM, with an excavation diameter of 8.75m, is the largest TBM to have worked in Hong Kong.

In an outstanding performance, it mastered difficult ground conditions and completed the second 1840 m drive, well ahead of schedule, in under five months. Despite difficult, heterogeneous and abrasive conditions, the NFM TBM recorded a best weekly progress of 162m and a monthly best of 540m.

NFM Technologies is proud to have been chosen for this major tunnelling project and to have the opportunity to demonstrate its broad range of skills and resources.

NFM TECHNOLOGIES, Tunnelling Department,

12, rue Juliette Récamier, 69 456 Lyon , Cedex 06, France,

T:+33 (0)4 72 74 75 04, F:+33 (0)4 72 74 74 74,

E: pgautier@framatome.fr