Your browser is no longer supported

For the best possible experience using our website we recommend you upgrade to a newer version or another browser.

Your browser appears to have cookies disabled. For the best experience of this website, please enable cookies in your browser

We'll assume we have your consent to use cookies, for example so you won't need to log in each time you visit our site.
Learn more

Welcome to the pleasure dome

While Dubai has made its name as a playground for the rich, Abu Dhabi is keen to establish itself as the cultural capital of the UAE. Ruby Kitching reports.

More from: Piling on board

Construction is underway to build the Louvre Museum Abu Dhabi off the coast of Saadiyat Island. Quite literally, it will be built in the sea, as is only possible in the mad world of Middle East construction.

The museum − the only overseas sister establishment of the Paris Louvre − will be built on a custom made platform, linked to the Saadiyat coast by two walkways.

When NCE’s sister magazine Ground Engineering met with museum designer Buro Happold last month, the full story was revealed. The project involves extending the coast out to sea over an area of 63,500m² using imported fill − the temporary platform − then digging down into it to install piles and basement storeys before constructing the gallery complex. This will consist of workshops, an education centre, restaurant and café facilities, and of extensive back-of-house support facilities, all sheltered by a 180m diameter dome.

Floating galleries

Client for the project is the Abu Dhabi government’s Tourist Development & Investment Company. The reclaimed land will then be nibbled back so the buildings will look like they are rising from the sea, allowing any area that is not a thoroughfare or has a building on it to be flooded. The result will be the creation of floating galleries.

“We are basically building a small town in the sea.”

Andy Websper, Buro Happold senior goetechnical engineer

“We are basically building a small town in the sea,” says Buro Happold senior geotechnical engineer Andy Websper. Last month construction of the temporary platform began.

Ahead of this, the area had to be safeguarded by way of a 15.3m tall rockfill revetment in water up to 16m deep. The water in the enclosed area will be displaced by selected fill material. A temporary cut-off wall down to rock will be installed as part of the dewatering to enable basement construction work to proceed in the dry (see ‘Construction sequence’ box below).

The revetment wall was designed by consultant Parsons International, the engineer for the Saadiyat-wide masterplan.

Local skills in plentiful supply

With local skills in sourcing and placing fill to create land in plentiful supply in the Middle East, it was decided it would be easier to place the material, build the structures on top and then cut back on the surplus land rather than trying to build lots of little islands to accommodate each piece of infrastructure or building. Dredging and placing is being carried out by contractor Jan de Nul.

“We’re building the platform, then cutting back to allow water to flow between buildings so that it looks like the structures are coming out of the sea,” says Websper.

“We’re building the platform, then cutting back to allow water to flow between buildings so that it looks like the structures are coming out of the sea.”

Andy Websper, Buro Happold senior goetechnical engineer

Getting the correct strength parameters for material in the temporary platform soil is paramount to the success of the Louvre’s construction and Buro Happold is leading a ground investigation to determine the site subsoil characteristics for detailed design to proceed.

“There is some potential for liquefaction [of the temporary platform material] to occur, particularly in the event of an earthquake, so we are checking density and soil grading,” says Websper.

Dewatering wells will be installed on the site ahead of piling and excavation operations, and will remain in place until at least the building is constructed. Dewatering will probably comprise a ring of deep wells at 25m to 50m centres around the inside of the cut-off wall with most wells positioned to avoid basement areas, says Websper.

Geology: Soil Profile

Saadiyat Island soil profile

Saadiyat Island soil profile

The coastal geology of Abu Dhabi (and the UAE as a whole) is dominated by a northeastsouthwest trending barrier lagoon complex of Holocene Age, says Buro Happold seniorgeotechnical engineer Andy Websper.

The barrier Islands, of which Saadiyat is one, take the form of oolitic sandy shoals and coral banks that are separated by steeply incised tidal channels. The solid geology is relatively consistent in the vicinity of Abu Dhabi City and comprises a sequence of calcareous sandstones and calcarenites over a deeper, gypsiferous mudstone sequence of Tertiary Age.

The Abu Dhabi government’s Tourist Development Investment Company is undertaking extensive marine works to re-profile the coast of Saadiyat Island, and has undertaken some limited ground investigation work of the site and surrounding area. The natural ground conditions typically comprise a mantle of made ground and/or recent sand deposits over interbedded sandstone, calcareous sandstone and calcarenite down to approximately 18m to 22m below existing ground level (the “carbonate sequence”).

These materials overlie a mudstone/siltstone/calcareous mudstone sequence (the “mudstone sequence”) with large lenses and beds of crystalline gypsum up to 2m thick.

 

Because of the relatively poor condition of the near-surface soils at formation level, a piled foundation solution has been adopted for both the dome and the general structures. Across the project, basement depths vary up to 8m below mean sea level, so many of the basement piles will have to work in tension to resist uplift.

Following completion of the temporary working platform, a further platform will be built from which piles will be installed to correct depth and cut off (depending on the extent of the basement).

The basement storeys will then be built using bottom-up construction methods and the superstructure thereafter. The surrounding revetment wall and surplus fill material will then be removed, the coastline reprofiled and the low-lying land allowed to flood (see ‘Construction sequence’ box below). A more detailed construction sequence will be developed with the contractor which is yet to be appointed.

A dominating superstructure

The Louvre superstructure is dominated by a huge 180m diameter dome structure that will be supported by four columns, each taking compressive loads of up to 30MN each. Large diameter piles arranged in groups will be used to resist these vertical loads. The current assumption is for 1.2m diameter piles with socket lengths in the rock of approximately 12m.

This will result in total pile lengths of between 13m and 19m depending upon the location and depth to rock below cut-off level. Basement structures and other buildings will be subject to various magnitudes of uplift force due to the groundwater, depending upon their relative depth. As such, the foundation piles will have to be designed for a range of load conditions.

“It is imperative that the drilling operation is well controlled and carried out to the highest standard so that we get accurate data.”

Andy Websper, Buro Happold senior goetechnical engineer

These load cases will change from the short-term construction case when dewatering will prevent uplift forces, to the long term when uplift forces will be significant, and will be subject to tidal variations.

The scheme design typically comprises 750mm diameter piles with 900mm diameter piles in the deeper basements. Pile rock socket lengths of between 10m and 18m will carry working pile loads up to 7,000kN in compression and 4,500kN in tension.

Piles have been designed using preliminary parameters and appropriate factors of safety; 2.5 for compressive loads and 3 against tensile loads, pending completion of site geotechnical investigation work, following which the design will be reviewed and concluded

From past experience, Websper adds, ground conditions consist of relatively young rocks, with very little jointing. Pile design is based largely on shaft friction rather than end bearing. One of the main design objectives is to limit tension and flexural cracks in the concrete to ensure seawater does not corrode reinforcement.

Optimising the design solution

Full site investigation with high quality cores and detailed logging is to be carried out soon. This will comprise approximately 31 rotary cored boreholes down to 40m across the site, with those near the dome foundations extending to 60m.

“This is important to optimise our design solution and it will, for instance, give us data that will be used to determine the degree to which we need to downrate the rock strength to allow for fractures.

“It is imperative that the drilling operation is well controlled and carried out to the highest standard so that we get accurate data and detect any voids or fracturing of the rock insitu,” says Websper.

Priceless art below sea level

Undoubtedly the most important aspect of this project is the housing of priceless artwork safely and to securely transport it in and out of the building.

The Paris Louvre will loan artworks, so it is of paramount importance that art movement and storage is secure.

This means that all artwork must enter the complex via tunnels and into basement areas before reaching the main galleries. The main gallery will sit above sea level, but the basement will be up to 10m below sea level and must be adequately waterproofed.

Saadiyat Island will eventually house four other museums and art galleries, including a Guggenheim museum in the quarter known as the Cultural District.

Sited on a built archipelago in the tidal zone of the Arabian Gulf, the Louvre Abu Dhabi should be one of the world’s most visited cultural destinations when it opens in 2013.

Construction sequence

1. Before: Original coastline

2. Building out: Revetment created to retain temporary platform

3. Platforming: Imported fill used to displace water and create platform

4. Water out: Cut off wall and well points installed. Dewatering begins

5. Piles in: Basement areas excavated and piling begins

6. Building up: Basement floors built and columns for dome installed

7. Back up: Areas backfilled, piling carried out for buildings without basements

8. Coverage: Dome constructed and coastline re-profiled

9. Final result: Revetment and temporary platform removed/lowered and areas allowed to flood creating a lagoon on the mainland

Have your say

You must sign in to make a comment

Please remember that the submission of any material is governed by our Terms and Conditions and by submitting material you confirm your agreement to these Terms and Conditions. Please note comments made online may also be published in the print edition of New Civil Engineer. Links may be included in your comments but HTML is not permitted.