Geotechnical control of tunnel works in Hong Kong

Hilly topography, intense urbanisation and infrastructure development, combined with limited land availability and a growing awareness of environmental issues, have driven Hong Kong's need to develop its underground space. By the end of 2012, about 460 km of tunnels had been constructed in Hong Kong. While private projects involving tunnel works have been subjected to statutory control to protect public safety for many years, geotechnical control of government tunnel works was only introduced through a government works policy instruction in 2005. This was one of the outcomes of a government review on the project implementation issues of a deep sewage tunnel project which encountered major construction problems due to adverse geology. The geotechnical control regime which was introduced took account of the development of geotechnical risk management internationally and notable tunnel failures both in Hong Kong and elsewhere. To facilitate geotechnical control, the Geotechnical Engineering Office of the Civil Engineering and Development Department has prepared technical references and guidance documents, including a catalogue of notable tunnel failure case histories. This paper traces the development of geotechnical control of tunnel works in Hong Kong, with a view to help in minimising the risk to life and property posed by construction of tunnel works.