The photos above are about a week old, I was just too lazy that's all.
Apparantly excavation started yesterday on the ocean heights II plot
If Imre doesn't post his pics here I'll post them
Also here's an article about 23 marina but also bitches about princess tower a bit
Sunday, 5 November 2006
58m piling paves the way for tallest resi tower in the world
by Christopher Sell
Around 182 piles of varying diameters, from 1,500mm to 1,200mm and 900mm will be utilised on the site. The project manager says that the most powerful piling rig in the UAE is being used for the groundworks.
Dubai’s coastline may feature an abundance of high-rise developments all jockeying for pole-position on the city’s skyline, but within the space of a few months, it is now going to get two towers both vying for the accolade of the world’s tallest residential tower.
Currently occupied by the 323m tall Q1 Tower on Australia’s Gold Coast, the emirate was supposed to be inheriting the title sometime in 2009 following completion of the Princess Tower. Standing at 107 stories and 414m tall, the US $188 million (AED690 million) project, developed by Tameer Holdings with ACC as the main contractor, is universally considered to be the holder in waiting.
Not so according to the developers of 23 Marina, a new development located almost in the shadow of the Princess Tower. This 90-storey, 390m tower, launched in October is also claiming to be building the world’s tallest residential building.
Can they both be right? RP Ranganatha, general manager, Hircon is ebullient over who is the rightful heir, refuting the claim made for Princess Tower, mainly because, he says, they [ACC] are building a mixed-use tower. “As it stands this [23 Marina] is the tallest exclusive residential tower in the world, and I say exclusive because although the Princess Tower is taller than us, they have a bit of commercial space. Though they claim it is just a residential tower, they have commercial, whereas we remain exclusively a residential tower,” he says.
Indeed, the Princess Tower does feature offices and sales outlets, whereas 23 Marina is looking to create a single residential neighbourhood within the structure. But semantics aside, the crux is that 23 Marina will still be the second tallest tower in the GCC, and as such likely to pose enough construction challenges on the ground as those across the boardroom table. It is a super high-rise residential building consisting of ground floor plus 88 floors with four basements below ground. The height above ground floor is 324m up to the last roof above which the roof features extend another 66m making the top of the building 390m above ground level.
The tower is being built by Dubai Civil Engineering, with KEO International as the lead consultant. Hircon International, a joint venture between the Hiranandani Group and ETA Star properties, awarded the contract of over $134 million. Hafeez Contractor’s from Mumbai, India is the concept architect. In total the building will have eight levels of parking, three levels of spas, fitness centres and indoor and outdoor temperature-controlled swimming pools. It will also feature a jogging track.
Swiss Boring Overseas Piling is currently on site in Dubai Marina, completing the substructure work and expect to finish the concreting of the piling work by the end of this month, when load testing can begin. It is hoped that this, termed phase one will be completed by mid-November. Phase two will see DCE come on board to mobilise and commence the superstructure. This is expected to last 1,004 days, with the floors being added in a three-day cycle, according to Emad Hammoudi, project manager, KEO International. The proposed structural system comprises shear walls and outriggers, perimeter columns and post-tension slabs.
With a somewhat shallow footprint of 56m, the tower will require significant foundations and it is unsurprising that, at 58m below ground, 23 Marina – with the notable exception of the Burj Dubai – will feature the deepest pilings in the UAE.
According to Anil Mishra, structural engineer, KEO, 182 piles of varying diameters, from 1,500mm to 1,200mm and 900mm will be utilised on the building site. The deepest and most frequent pilings appear at the centre of the footprint where 91 piles of 1,500mm will be sunk. Moreover, 68 1,200mm piles will be sunk 44m either side of the largest piles. And finally, 23 900mm piles will be sunk, encircling the perimeter of the entire site. Mishra adds that the site is home to the most powerful piling rig in the UAE, and it happens to be the only one in the country too.
Surprisingly, however, for a tower of such height and narrow footprint, no damping mechanism has been incorporated into the design. While Mishra voiced his surprise at this omission, Rafi Sheikh head of structural department, KEO explains that without, it is a more efficient and cheaper building process. “The structure itself provides enough damping properties. We have done a study by RWDI in Ontario. They confirmed that building range of acceleration is 15.9 and it has to be between 15 and 18. So it’s very comfortable.” Sheikh adds that the sway at the top of the building will be 450mm each side. Otherwise, Sheikh continues, a damping system is highly expensive, difficult to maintain, and it is hard to ensure they will definitely work.
Furthermore, independent third party checking was carried out by French consultant Socotech in Paris and KEO’s design was verified as being safe and in compliance with regulations. Garassino of Milan, Italy carried out pile group effect studies. Allied to the wind tunnel tests, motion perception studies were conducted by Motioneering of Ontario, Canada, while test pile load-deflection studies were carried out by Loadtest Asia of Singapore.
For the excavation, which currently is at -4m, a diaphragm wall has been constructed, going down 18m and is 80cm thick. Once the piling has been completed, the excavation level will go down a further 8m to -12m. To compensate for the Gulf’s water table, Swiss Boring has installed 24 de-watering wells, placed inside and outside the wall, running continuously to enable construction to take place.
“The de-watering is important, as if it didn’t happen, you would be water-logged and you simply couldn’t build. And from here we need to go down another 8m” says Mishra. The piling work has to be completed first before any excavation takes place, adds Mishra simply because the logistics of transporting the supplies to construct the pilings - concrete, rebar and so forth – any deeper would be extremely difficult.
But the problem that most concerns Mishra is access to supplies and labour, to ensure that work can proceed smoothly. “It is not so much the work itself, the bigger problem in this country are supplies. If you get them at all. In order to get things done on time you need people to do it. And those people are not there all the time because they are on other sites,” he says.
With 73% of all the apartments already sold, according to Hircon, clearly customers in the UAE are not particularly fazed whether it can justify its claim as the world’s tallest residential tower or whether it features a damping system. As long as it provides accommodation to meet Dubai’s metronomic growth and demand for high-specification property, there seemingly will always be someone looking to fill it. The prospect of living in accommodation certified by the Guinness Book of World Records would simply be a bonus.