By Christopher Sell
Crashing a spaceship into a desert is the latest idea to hit the Dubai construction industry. Stargate, the futuristically named education complex in Zabeel Park, is boldly going where no one has gone before, despite the small task of waterproofing. Christopher Sell reports.
When it was announced in September 2005 that a new, high-tech family entertainment complex was to be built in the centre of Dubai, you might have been forgiven for thinking it would contain innovative features and stunning aesthetics.
This is Dubai after all, where simplicity is scorned and the complicated welcomed.
And to that extent, you would be right – for the Stargate development, located slap bang in the middle of Zabeel Park will contain some novel and enterprising activities to entertain and tax the minds of Dubai’s younger population.
But for this to happen it is also going to tax the minds of those responsible for building it.
For the concept of this development is created around two animated characters who crash-land their spaceship in the middle of the park.
Therefore, a significant proportion of the site will need to be below the ground.
Designed by Germany-based Kling Consult, with ECC as main contractor and due to be finished in May 2007, the centre is designed to be a mixture of education and family entertainment catering for children between four and 14 years old.
Dubai-based Osus will build, operate and transfer (BOT) the project on behalf of, and in partnership with, Stargate owners Dubai Municipality.
In fact, according to Justin Larsen, construction manager at ECC, between 60 and 70% of the structure will be below ground level.
This necessitated the removal of 140,000m3 of earth, the first of numerous challenges faced by the team during construction.
And like many other construction projects in Dubai, the high water table in the emirate created difficulties for the groundworks.
A sophisticated dewatering system was installed to ensure the site remained dry 24 hours a day, according to Larsen.
“Because the raft slab is 2.7m below sea-level, we had to install a de-watering system with approximately 140 well points around the circumference of the site, to draw down the water table to a level which enabled us to construct the raft slab and retaining walls without the presence of water,” he says.
“This system will remain operational until the structure has been completed, because the hydrostatic pressure has the potential to float an incomplete building.”
Due to this permanent presence of water, a significant concern for the construction team was therefore a waterproofing system that ensured the building would not suffer any damage.
For this, a loose laid system was employed that will be flexible enough to accommodate any movement once the building has been finished.
The team are being so careful, that they are waterproofing the structure up to 6m above ground level.
“The waterproof membrane was chosen because the loose laid system can allow for movement and it is reinforced to withstand the hydrostatic pressure,” says Larsen.
It isn’t just below ground either that the water has to be factored in.
Stargate’s design also features a 2% fall from the middle of the complex to the edge, to ensure that precipitation does not settle and place undue loading pressure on the structure.
This represents a 1.1m rise from the outside to the centre.
Although Larsen considers the rest of the construction as fairly basic structurally, once these problems have been surmounted, he points out that the design of the project sees predominantly non-linear shapes with curvatures and bends featuring heavily in the structure.
“Another aspect of the design is there are a lot of curves and odd shapes, which you don’t traditionally get on building sites, there are a lot of different shapes and angles.
That is quite unique,” he says.
Therefore, when it came to building the formwork for the building, where normally you would require one formwork for a high-rise tower, for example, Stargate required Larsen to construct four different formworks for various areas of the project.
With a site footprint of 19,000m2 measuring 700mm thick, the total amount of concrete used for the raft slab is 14,000m3 with 2,500 tonnes of reinforcing.
The waterproof membrane occupies 26,000m2 while the total amount of concrete used totals 30,000m3.
The total reinforcing steel is 4,000 tonnes. Larsen hopes to have most of the concrete work finished by the middle of January, although he is aware the supply of raw material could be a factor before the end of construction.
“The materials are pretty common in this area, but because so much construction is going on, lead times have changed, as have prices.
We haven’t experienced any delays yet but we were discussing it with regards to aluminium cladding – pretty much every building in Dubai has it,” Larsen says.
Stargate’s main attractions are spread across five domes: Saturn, Moon, UFO, Earth and Mars will each offer a unique experience.
Inside one dome is ‘D3D’ high-tech ‘edutainment’ theatre offering laser shows, 2D immersive video, 3D shows, 3D interactive games and corporate events, whilst the ‘Lunar Show’ will enable children to cavort in snow all year round.
Five corridors – or ‘wings’ of the spaceship – provide exhibition and retail spaces on various themes and there will also feature a 500m ‘Foot Coaster’, which will be Dubai’s first completely indoor walking and cycling track in a climate-controlled environment, that runs the entire outer perimeter of the Stargate on the mezzanine level below ground.
The ground floor slab for the earth and lunar sectors are already in place and construction on the first dome is imminent.
Each of the five segments should take about a month to finish and Larsen has scheduled 70 construction days to complete all the domes, the completion of which is paramount as it then allows lighting to be fitted and the interior design work can begin.
The domes are all constructed in situ and vary in size depending on the sector, with the largest occupying the UFO zone, which spans 40m in diameter and rises to a height of 10m.
Larsen adds that around the dome, a go-kart track would be added which presents further health and safety issues to do with live loads and dead loads placed on the slab.
Started in February 2006, and earmarked for completion in May 2007, the US $68 million (AED250 million) project currently employs 460 labourers, although this will increase over the next few months to 600.
Provided Dubai’s fluctuating water table causes no problems in the future, children should be able to enjoy the delights of high-speed electric go-karting, rock-wall climbing and family rollercoasters for years to come, oblivious to the lengths contractors must go to get the site built in the first place – just as it should be.
“Between 60 and 70% of the structure will be below ground level.
This necessitated the removal of 140,000m3 of earth ...and like many other projects, the high water table in Dubai created difficulties for the groundworks.”
“Because the raft slab is 2.7m below sea-level, we had to install a de-watering system with 140 well points around the circumference of the site, to draw down the water table to a level which enabled us to construct the slab and retaining walls without the presence of water.”
Justin Larsen, construction manager, ECC