Laing O’Rourke - Hsin Chong - Paul Y Joint Venture is using the single-sided Megashor system in construction of the West Kowloon Terminus. Once complete, the £7bn high-speed rail line and terminus will connect Hong Kong with mainland China. RMD Kwikform has also been heavily involved in earlier phases of the Kowloon terminus project.
The terminus is being built next to the busy city and the sea and the 2m-diameter supporting walls required extra heavy-duty shoring support that could cope with large pressures and meet the fast-track programme.
In order to meet the technical challenges of the project, the Hong Kong design team took advantage of a newly UK-designed Megashor shoring system, comprising five specialist components, all of which were fabricated locally.
Rory O’Gara, sales manager for RMD Kwikform, said: “With the new system, instead of fabricating specialist steel shoring, the five Megashor components could be combined with existing Megashor equipment to form individual modules. These can then be crane-lifted into place and connected together to allow for large wall sections to be poured.”
The components themselves are comprise additional leg sections with prop connections, Megashor jacks at each end of a prop and a new connecting cross-section with web-ties and square plates. “Thanks to the flexibility of the system, the on-site team are able to work in-between the main wall propping supports to cast the wall sections,” said O’Gara.
To meet the overall challenges of the project, the RMD Kwikform team had to design and support the construction erection sequencing of the wall shoring, to deliver concrete walls that were 230m long, 2m thick, and 8.8m high, on either side of the station. Hard rock faces varied the width of the wall sections and so the concrete pours were split into two or three stages. The flexibility of the Megashor system enabled the site team to add and remove modules, adjusting components to meet the site needs.
O’Gara added: “Because of the location of the station with sea and city walls, we were not able to use traditional wall formwork designs with anchors, which meant the Megashor had to be single-sided. To solve this, we modelled the sections and supported the team with location points to cast-in ground anchors, meaning the full load of concrete pressure could be taken back into the ground by the use of single angled ties at the base of the shutter.
“Throughout the design process we had to consider how to tackle the high concrete pressures. With the new Megashor system, we were able to create 3.6m sections, that could be moved around the site by cranes allowing the team to complete the 21 pours required for the job.”
In addition to the Megashor wall formwork solution, RMD Kwikform also supplied Alshor Plus shoring to construct all of the slabs and overhead ducts along the train line. In total, 1,638 tonnes of equipment were delivered to site.
Stephen Togher, construction manager for Laing O’Rourke saod: “Being able to use the modular Megashor solution, to construct the 21 pours, allowed us to meet our extremely tight construction schedule. The ability to add and remove part of the forms, as well as easily order extra forms required as the programme dictates, has helped us to complete this wall ahead of time, enabling us to beat programme.
“The Megashor single sided system is quick and simple to use, meaning I am very likely to use it on future projects and I would recommend it to any contractor undertaking similar work.”