Hydrodemolition for Hong Kong station upgrade 9 June 2015

Hydrodemolition technology from Aquajet of Sweden is proving its worth as part of the Contract 1112 upgrade to MTR’s Hung Hom Station in Hong Kong.

Leighton Contractors (Asia) acquired the hydrodemolition robot from Aquajet to enable completion of sensitive demolition work at the existing station. The work, which includes significant modifications to the existing MTR station, platforms and tunnel box, is a critical element of construction of the new 17km Shatin–Central Link (SCL) serving the New Territories, Kowloon and Hong Kong Island.

Aquajet’s Aqua Cutter 710V Evolution

Asia Waterjet Equipment (AWE) Co of Singapore, distributor in Asia for Aquajet Systems AB of Sweden, delivered the Aqua Cutter 710V Evolution machine and is providing training on site. The design allows the operator remote control freedom to reach all horizontal, vertical and overhead areas at a distance of up to 7m, without support.

The existing Hung Hom Station requires integration with the new station, and extensive underpinning and modification of the existing podium structure of the station is needed.

One of the greatest challenges faced by the contractor is that the major civil works are to be constructed beneath the existing podium slab, which leaves an operating headroom of just 5–7m. Construction must also take place under and within an operating railway station, with no disruption to services.

“Part of the work includes the cutting of shear keys in diaphragm walls,” explained Patrick Lee, regional sales manager of AWE Singapore. “The robot had to remove an average of 450mm of concrete with three overlaying layers of rebar in between.”

Hydrodemolition technique protects rebar

“It is impossible for traditional methods, using jackhammers, to reach the required depth without damaging or destroying the rebar, but the Aqua Cutter is able to perform the cut with a high degree of accuracy and consistency and provide a good finish for the next phase of construction,” said Lee.

Another consideration is that Leighton had to carry out operations in an existing tunnel beneath office buildings and hotels.

“Jackhammers would have made tremendous noise and vibration, which can be transmitted via the foundations to the buildings on the surface,” said Lee. “This would have caused a great deal of disturbance to office staff and hotel guests, and in extreme cases the vibration can even cause damage to the structures and their interiors.”

The remotely controlled Aqua Cutter, however, could be steered through the tunnel to carry out the necessary work without causing any disturbance.

“Leighton personnel were very impressed when we demonstrated the machine to them prior to purchase, and they actually made up their minds on the spot,” said Lee.