As the Hong Kong Zhuhai Macau bridge is opened RMD Kwikform explain one of their many roles in the construction of this mega project, a real feet of human endeavour.
RMD Kwikform has been involved with the project since 2014, having previously supported major works for the land phase of the bridge, which connects Hong Kong to China across the Pearl River.
The HKZMB will establish a new transport link between Hong Kong, Macao and Zhuhai, towards the Western Pearl River Delta, becoming one of the world’s longest bridges.
For this phase of the project, RMD Kwikform supplied a range of formwork and shoring solutions, including its heavy-duty Megashor shoring to support the construction of the turnaround facilities in the water, over the marine viaducts.
Composed of different concrete elements, the formwork and shoring solutions required to support the construction of the whole turnaround structure, were both complex and varied. The first main challenge was to design support structures for the placement of two precast segment on pier (SOP) base slabs. This was followed by formwork and shoring for two sets of in-situ cast side and end walls, and top and wing slabs, with the structure completed using shoring mounted on steel beams to cast the final in-situ decks.
In order to form an elevated road across the existing new bridges, further support was required to place four precast girders, four precast I-Beams and four precast corner beams. Once these main precast sections were installed, shoring solutions were designed to cast the elevated bridge decks and key connection segments to the main precast slabs.
With two sets of SOP’s required in total, each set needed to be complete simultaneously in just four months for this section of the project to stay on programme. To achieve this RMD Kwikform worked with the DCV JV team to plan the construction sequence of the project, in line with the lift capacity of the barge crane.
Commenting on the construction sequence and the design of the formwork solution, RMD Kwikform Deputy Sales manager, Martin Chan, said: “The turnaround facility is located in the Western Waters of Hong Kong and spans over the top of the main dual three lane bridge. This meant the overall structure had to be built using both deck mounted and barge mounted cranes.
“In order to cope with the loads from the precast sections and the additional Hong Kong typhoon wind loads we designed solutions based on our modular Megashor heavy-duty shoring system. With a requirement to support the turnaround facility from the top of the cast in-situ pier, we designed two identical Megashor tower arrangements, each side of the main bridge, reaching a height of just over 19 metres.
“Positioned on top of cast in-situ pile caps, each matching tower arrangement was pre-assembled in two blocks on a large barge and lifted into place, using its deck mounted crane. To complete the 19-metre height, two types of steel spreader beams were connected to the tower, which in-turn supported the main primary beams.
“The bottom half of the tower, measuring 6.7 m long by 6.3m wide by 7.7m high was made up of four sets of nine Megashor legs, connected together with steel SuperSlim soldiers and bar bracing. This base section was a pretty standard heavy-duty tower setup, supporting what was a much more complex second section comprised of a main tower and Megashor raker frame arrangement.
“This upper section was designed to have a total span of 16.9 metres to support the spreader beam and in-turn the SOP precast base slab. In order to achieve this, the block was made up of a 6.7m long by 6.3m wide six leg inner tower together with outer raker frames.
“The frames themselves were made up of three Megashor legs connected together with steel SuperSlim soldiers combined with Slimshor jacks to create the braces between the raker frames and main towers, in order to form the angle required to achieve the large span off each side of the tower.
Making the connection between top and bottom towers
“In order to connect the six leg upper section and Megashor side raker frame arrangement to the base section, specially fabricated heavy duty, angled nodal brackets were mounted onto the top of the base section creating a strong and stable support tower arrangement.
Building in safety
“In addition to the main tower support structure, RMD Kwikform designed safety platforms, access and egress solutions to support the teams working on the project throughout the construction phase.
Martin: “Once the main support structure was in place, the precast SOP base slab was lowered onto the primary beams and stitched into the pier. The site team then used standard formwork, including Aluminium Alform beams, SuperSlim Soldiers and GTX beams to cast in-situ the SOP sidewall, end wall, top slab and wing slab.”
“At the same time as these sections were being cast, the site team was erecting two Megashor support towers on the deck of the main bridge structure used to support the other end of the main precast girder.
By designing the overall solution and main towers to use as many standard components as possible, coupled with locally fabricated specials, the RMD Kwikform team was able to accelerate the design process with the DCV JV team enabling erection of the equipment to commence much quicker than any alternative bespoke option.
Martin adds: “As well as the complex design, we were challenged on delivery, erection and dismantling time, especially as the tower system had to be erected on a barge. Although each tower was the same, we also needed to be able to build in flexibility to alter the heights of the towers so that we could meet the exacting requirements. This is why the use of Megashor jacks were so important.”
“In conclusion, it was the collaboration between the DCV JV team and RMD Kwikform that enabled the solutions to come together in a practical and cost effective way.”
About the project
The Hong Kong – Zhuhai – Macao Bridge (HKZMB) is a multi-million pound project, first suggested in 1983. The bridge spans 29km, making it one of the world’s longest bridges.
The bridge is expected to encourage a deeper economic integration between Hong Kong and China, improving access to global markets, enhancing the flow of labour and goods, and strengthening the growing tourist industry.