A little way off the shore of Dubai lie several beautiful islands in the shape of gigantic palm trees: Palm Jumeirah, Palm Jebel Ali, and Palm Deira, still under construction. Each consists of peninsulas extending from a trunk attached to the Dubai coastline, and topped further seaward by a great seawall for protection. It must have taken a lot of geotechnical consultants to make the necessary examinations of the site’s seabed, each geotechnical consultant an expert in seabed engineering. Because making an island out of loose undersea sand will take a lot of engineering expertise even before anything can be put down on paper, prior to making any physical construction.
The Palm Jumeirah Crescent or breakwater is just 13 feet higher than the sea level at low tide, and rises from 34 feet of water at its deepest point. Its engineers contend that it is high enough not to sink in the rise of the sea level should global warming really geotechnical site investigation occur, or any tsunamis that might develop in the Persian Gulf. The breakwater is made from rocks blasted from the mountains. At its base is sand covered by a geo-textile or woven fabric to prevent the sand from moving out. Weighing down this ‘wrapped’ sand is a layer of one-ton rocks, over which two strata of six-ton rocks sit to form the top part.
The peninsulas jutting from the central avenue are created also from sand dredged from the seabottom and then vibro-compacted to support structures. Palm Jumeirah was created from 3,257,212,970.389 cubic feet of sand. Vibro-compacting is performed by saturating the sand with water then vibrating it via probes to make the sand settle more densely. First a probe is inserted into the sand sub-surface through water saturation and vibration. As the probe reaches its intended depth, loose sand is poured into the cavity made by the vibrator probe. Thus a denser zone of sand is created, enough to support construction.
However, vibro-compaction may be appropriate only in clean sand where silt content forms only 15% maximum.
In each peninsula or frond are two lines of residential estates or structures for the really rich, and anyone can buy his place there. Palm Jumeirah is expected to house 120,000 residents and laborers, plus another 20,000 tourists each day. So it is not really a small island where solitude can be found, but a gigantic self-contained suburbia of the really, really wealthy. There are at present residents living in the islands: real residents, vacationers, speculators and workers giving finishing touches to some parts of the reclaimed areas. A six-lane highway today serves as the transportation artery in and out the fronds, but in the final stages, residents will also be serviced by a monorail.
Palm Jumeirah and the other man-made islands exemplify what modern engineering backed by a lot of money can do. While reclamation from the sea to create islands may not be a novel idea since it has been done many times before, the project’s massive size makes it so.