activities archive

Technical Visit to KCRC Contract LDB 201 Sheung Shui to Chau Tau Tunnel on 26 Feb 2005

Date: Saturday, 26th February 2005

Time: 9:00 am to 12:00 pm

Program Highlight:

On 26 February 2005, 21 members of ASCE Hong Kong Section had the chance to take past in a site visit to KCRC Contract LDB 201 – Sheung Shui to Chau Tau Tunnel.

The visit began with a presentation by Ir Charles Yeung, Resident Engineer of KCRC. He introduced the project background and the use of Tunnel Boring Machine (TBM) as the main tunneling technology in this project and related special site arrangements associated with the use of TBM.

The Contract LDB 201 is a lump sun design and build constract of $2.8million HKD. As a part of the KCR Lok Ma Chau Spur Line, this project mainly consists of construction of 5.2 km long tunnel. Among the 5.2 km, 3.3 km is TBM tunnel, 1.1 km is cut and cover tunnel and the rest 0.8 km is ramp structure. Due to the mixed geology (70% soft ground and 25~30% rock), earth pressure balance type TBM which enables drilling in mixed ground conditions was used. Ir Yeung gave an extensive explanation of the technology in TBM, including the different modes of operations for various ground conditions, computerized positioning system, working conditions in TBM, operation and maintenance cycle as well as the constraint limiting the progression speed of a TBM – surprisingly, not about the cutter head, but the conveyer belt transporting the spoil. When drilling in soft ground, the average traverse speed is up to 15 rings per day, with a maximum of 25 rings and when in rocks, the average traverse speed is 7 rings per day, with a maximum of 11 rings. Each ring is 1.8m wide consisted of 7 precast concrete segments with a tapered key segment to control the curvature (both vertical and horizontal) of the tunnel. Since the segments form the final formation of the tunnel. Therefore, the diameter of the completed tunnel is identical to the outer diameter of the cutter head, which is 8.75 m.

Members were then led to the tunnel and see the finished segment. We gained valuable experience on TBM tunnel construction. On be half of the Section, we would like to express our sincere thanks to KCRC and site staff, especially Ir Charles Yeung for their hospitality.