ABSTRACT
Critical challenges are faced by engineers with the mission to construct tunnels underneath live railways with certainty on settlement control and safe operation of metro line. There are two box jacking projects in Hong Kong which have recently overcome the ground difficulties and completed jack box tunnels with a maximum width of 50m. One of them serves link road carriageway tunnel and another will serve connection of passenger mover and baggage handling system to a new airport concourse. The design engineers, construction specialists, supervising officers, client and railway stakeholder worked as one team and overcome challenges from scheme, design, and construction. This paper will cover the methods of controlling ground movement with live operating rail with stringent requirements. These include compensation grouting, pre-excavation grouting, roof canopy, tunnel face support, groundwater control, real-time monitoring of track and the management procedures to communicate with railway operators. Both box jacking projects have been successfully completed with the unified commitment and collaboration of the engineers involved from the design, construction, supervision and the client.
