ARTIFICIAL ISLANDS
Although Artificial Island has gained popularity and is now viewed as a modern method, their history is actually very old. Even the ancient Egyptian civilization employed it. It was heavily
utilised in the 17th century for land base, ventilation in coal mines, coastal defence, and oil exploration and production platforms. Japan has built numerous artificial islands totaling 1000
sq. km. around it. Technology has advanced so much in recent years that it is now feasible to build artificial islands in 75-metre-deep seas.
Artificial islands are designed and built taking into account the following factors:
- The first and most important factor that affects how an artificial island is designed is the depth
of the water. The complexity of the concept and execution increases with depth - The size of the waves that slam onto the building.
- The ocean’s currents
- Top building supplies are close and readily available
- Existing cables or pipelines
- Environmental protection and the local flora and fauna
- Earthquake risk and the state of the foundation
The following steps are involved in building an artificial island:
1) Dredging
In order to build harbours, channels, docks, de-silt lakes, or deepen waterways, dredging is
the process of removing the top loose layer of the water bed. Additionally, it is known as
maritime transportation. Dredgers are a particular kind of machine used for dredging. The
following variables affect the various dredging techniques:
- Depth of dredging
- Types of soil
- Operating environment
- Water depth, soil density, strength, and grain size
- Level of automation employed, among other things
2) Bed Preparation for the artificial island
A crucial step in building an artificial island is creating a solid and hard bed on the
water’s surface. Following the dredging of the top loose soil and the discovery of hard
strata, the following happens:
- The source of the material is important when choosing an island site, as was
already mentioned. The cost dramatically rises if the material is far away. - The best sand to use for bed preparation is coarse, high-quality sand.
- This sand is dropped from the waggon directly onto a dredged construction
site. - Sand is moved to the necessary locations with the use of a stationary dredger
as soon as the water gets shallow. - Rack revetments and a layer of armour rocks shield the sand from the waves.
- Bitumen emulsion is sprayed on the top layer of sand, followed by a layer of soil.
- On the embankments, appropriate grass is planted to decrease soil erosion.
3) Concreting
The concreting procedures for building an artificial island involve the following steps:
- Driven into the seabed are temporary tie rods, sheet piles, and tube piles, in order to help the
border rocks. - On either side of the sheet piles are boundary rock bunds.
- Hydraulic fill is placed in between the rock bunds to drain the sea and create an island.
- To protect the island from waves, concrete armour units have been permanently erected all
around it. - To stabilise the structure, piles are now being pushed into the seabed.
- A cofferdam is installed after evacuating a portion of the island’s interior.
- The base is covered with a thick concrete slab.
- A retaining wall made of reinforced concrete surrounds the island.
THE CASE OF DUBAI
Dubai’s Palm Islands are located 5 kilometres into the Persian Gulf. Even from space, one can see the Palm Jumeirah. It is the world’s largest artificial island. The United Arab Emirates' most populated city and emirate is Dubai. The islands were built in order to produce more beachfront
real estate, and the city is a favourite vacation spot for affluent travellers.
Dubai, one of the richest cities in the world, is twice as big as London. Dubai’s economy was expected to crash in 2016, as it was thought that the country would run out of oil. Dubai needed to develop a new revenue stream. To save his nation, the Crown Prince Sheikh Muhammad bin Rasheed Al Maktoum came up
with a $2 billion proposal. His goal was to make Dubai the world’s top luxury destination.
Why were the Palm Tree Islands constructed?
Due to its sunny climate throughout the year, Dubai is the ideal location for the notion. It has a lot of beaches, hotels, and resorts, as well as a lot of malls. The Sheikh wants to triple the number of tourists visiting Dubai annually from 5 million to 15 million. However, Dubai’s shoreline is only 72 km, which is insufficient for the anticipated 15 million tourists. The island’s circumference was expected to be 5.5 km, lengthening the coastline by 56 km. The extraordinary concept called for establishing an urban centre on the island. shopping centres, eateries, lodging facilities, hotels, and residences. The island was supposed to house
22 opulent hotels. In order to blend in with the surroundings, the island was to be constructed out of sand and gravel rather than concrete. For its construction, 94 million cubic metres of sand were needed. A 5.5 million cubic-metre rock breakwater was planned to provide protection from
the sea.
Perhaps more than any other Dubai megaproject, the Palm Islands have drawn criticism from environmentalists. A whole square mile of coral was destroyed by the extensive dredging required to construct the island, which also significantly altered the wave, temperature, and erosion patterns in the Persian Gulf. The World Wildlife Fund still insists that the UAE is "five times more unsustainable than any other country" on Earth. The first Palm was supposed to have 120,000 residents, but only approximately half of that number actually resides there.
The odd fractal shape of the island has caused stagnant water, algae, and insects, so not all of the inhabitants are thrilled about their new manufactured paradise. Due to declining Dubai real estate values, the two larger palm-shaped islands are still
under construction.
SUMMARY
Artificial Islands have been a significant development in the field of civil engineering since the end of the twentieth century. There are broadly three steps involved in the construction of artificial islands: dredging (removing the top loose layer of the water bed), bed Preparation for the artificial island and concreting.
References
https://theconstructor.org/construction/artificial-island-construction-methods/16380/
https://www.cntraveler.com/stories/2015-11-23/the-real-story-behind-dubai-palm-islands
https://www.wermac.org/civil_eng/palm_island_dubai.html
https://geology.com/satellite/artificial-islands-of-dubai/
Author : Niharika Sangwa
