Construction of twin stacked railway tunnels through mixed ground conditions
in the heavily populated urban environment of Hong Kong, including tunnelling in
poor ground conditions, with low cover and under or adjacent to sensitive
structures with minimal impact was the challenge presented by the tunnelling
section of the Kowloon Southern Link project.
This paper details how twin 1.1 km tunnels of 7.0 m internal diameter were
driven by Mixshield tunnel boring machine (TBM) in mixed ground through one of
the exclusive shopping and hotel districts in Kowloon. The paper addresses the
challenges required to be considered and managed for the success of the project,
including ground conditions, TBM selection, Mixshield TBM operation, settlement
monitoring and control, ground- borne noise and vibration, proximity to
utilities, buildings, roads and operating railways.