Launching of Hong Kong’s largest dual-mode Earth Pressure Balanced (EPB) Tunnel Boring Machine (TBM) – 14m in diameter – was held on 31st August 2015 in the North Portal. This was the first major milestone of this project, which is part of the vital cross-border link contributing to the sustainable long-term development of the city.
More than 300 guests attended the event, including government officials; management of Bouygues Construction, Bouygues Travaux Publics, Dragages Hong Kong; working partners; and our project team members.
Five senior government officials, a representative from AECOM (the supervising officer), officiated the ceremony, together with our senior management team, namely Jean Philippe Trin (Deputy CEO of Bouygues Construction), Christian Gazaignes (CEO of Bouygues Travaux Publics), Nicolas Borit (Managing Director of Dragages Hong Kong), Michel Bonnet (Director of Operations – Civil Works of Dragages Hong Kong), Daniel Altier (Project Director of Dragages Hong Kong).
This TBM, Hong Kong’s largest dual-mode EPB TBM, is also unique in terms of its “3-step” operation. First, the TBM slides into the 200m-long, 23m-wide South Bound Tunnel; second, the TBM will continue to drive while enlarging the tunnel behind the machine; and third, the TBM will turn from one tunnel to the other inside the Mid-vent cavern. This “3-step” operation is an exemplary technical first, minimising disruption to the community while also optimising programme efficiency.
The project is to be delivered using innovative solutions to attain the highest safety standards. Heavy investments have been made on R&D in the development of creative solutions by our parent company in France. This TBM is equipped with our in-house technology, namely MOBYDIC and TELEMACH, to enable real-time geological mapping of rock faces, as well as robotic detection and change of damaged components to reduce the need for manual inspection in front of the cutter head. This will maximise the health and safety of our teammates, and greatly enhance work efficiency.
To pave the way for the break-in of the TBM, a 200m-long, 23m-wide tunnel was excavated. Again, this was a “first” in Hong Kong – it is the largest-span tunnel ever excavated by mechanical means.
The project team anticipates the first tunnel breakthrough will take place in 2016.
Achievements and Future Works
North Portal / Administration Building
Excavation commenced in May 2014 and approximately 530,000m3 of materials were excavated and removed from site, forming the tunnel portals and paving the way for the site installations of the TBM. At peak, 15 excavators (each 80T) and 500 dump trucks were deployed each day.
As of end-August 2015, 254 tie backs (each 50 metres long) have been installed. This 20m-high temporary wall will soon be completed to allow the construction of the North Bound Tunnel in September 2015. In parallel with these works, TBM site installation works, together with construction of the retaining walls, are being carried out simultaneously.
Upon completion of the temporary steel bridge, constructed over the MTR railway, some 128,100m3 of earthworks conducted in hard rock stratum and substantial completion of site installation works were achieved in the 2nd quarter of 2015.
Excavation of the North Bound Tunnel by traditional methods commenced in April 2015. Progress of works has been going smoothly, with 42 metres now completed Full Face.
In the South Bound Tunnel, the project team has managed to reach 23 metres Full Face, despite very hard rock conditions.
Blasting operations are scheduled to commence in the 4th quarter of 2015. In the course of conducting blasting preparatory works, foundation works and wall construction of the South Ventilation Building are now also in full swing.
Following completion of the 320m-long adit by traditional drill and blasting, we have now commenced excavation of one of the city’s largest caverns. This 21m-high, 23m-wide and 47m-long cavern will receive the break-out of the 14m-diameter dual-mode EPB TBM in 2016.
Shortly before celebrating our TBM launch on 31st August, excavation of the top part of the cavern by drill and blast was achieved on 24th August.