Dubai’s Trade Centre Hotel is demolished with a bang

World trade centre hotel is demolished to make way for a new twin-tower complex offering 377 luxury units

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By  Colin Foreman Published  April 9, 2005

Dubai’s Trade Centre Hotel is demolished with a bang|~|67 Proj Body.jpg|~||~|With so many new building developments that are springing up around Dubai, one can be forgiven for forgetting that what goes up, must ultimately come down. Last week, the World Trade Centre Hotel reached the end of its life as it was demolished to make way for a new luxury residential development. Construction Week visited the site to find out how a building is reduced to rubble safely without damaging any nearby property. Before any explosives could be placed inside the hotel building, there were a number of key preparation phases that had to be completed. The first phase was the soft stripping phase that cleared all the timber and metal fixtures from within the building. If this was not done properly then the material would get mixed up with the rubble after blasting, making it much harder to process during the clean up phase. Removing the interior fixtures also provided access to all of the structural members for placing charges. On the main blast floors all the non-structural block work had to be removed — and in the case of the World Trade Centre Hotel, there was a great deal of block work that needed to be cleared away. This was done to give full access to the structural members so that the full length could be drilled along to give the explosive charges the maximum effect. Altogether some 3000 holes were drilled for a total of 200 kg of explosive charges. “This accounted for the majority of the work. We have been on site seven weeks; the first four-and-a-half involved taking out the block work, soft stripping and all the pre-weakening,” says Richard Green, the project manager for Controlled Demolition Group. Once all the pre-weakening work was completed, several layers of protective wrapping had to be applied to prevent the unwanted spread of debris during the blast. The first layer of protection was a chain link fence, and the second a black geotextile fibre mesh to stop smaller pieces of material from flying out and causing damage. “The protection is very important. If you set off the explosive charges with no protection there would be concrete flying for 50 to 100 m, breaking windows and causing extensive damage,” explains Green. The final phase was the charging that ends with the blow down and the clean up. All of the explosives used for the demolition are placed in drilled holes so that 95% of the energy created by the explosion is used to break the concrete. “If the charges were just set off in the open then the majority of the energy would be wasted in the blast and break every window in the World Trade Centre and Exhibition Centre,” says Green. As with any major project, a lot of planning was involved. This is doubly important when explosives are involved because the consequences of something going wrong can be extremely grave. “At the beginning of the job, a structural engineer and the explosives engineering team decided what time delays to use to blast each part of the building, so that it is dropped in the right place,” says Green. “There’s no manual that tells you how to blow down a building, so you can only really work from experience. Controlled Demolitions has a five man explosive team with over 100 years’ experience of working with explosives,” he adds. The blow down took out the first two floors of the building, with 3 m taken out from the columns on the ground floor, 1.5 m taken out on the first floor and another 1.5 m taken out on the fifth floor. With this support taken out, the building used its own weight to take itself down. “The hotel was particularly challenging because it is a small building that is very strong, and they tend to be the most difficult. Bringing down a tall building is much easier because if you knock out a couple of floors, the weight of it powering down will crush the rest of it and make it collapse. This building isn’t very big, which means you have to take enough out to let it drop sufficiently and collapse,” says Green. A major concern when planning the blow down was the proximity of the World Trade Centre, which is only 10 m away across the main access ramp. The initial plans meant that the site would have been even more compounded by the old car park that connected onto the west of the hotel, but that was demolished before the blow down took place. This meant that the blast had to pull the building down away from the World Trade Centre, and the detonator delays used, reflected this. A series of explosions were used instead of one big blast for two main reasons. Firstly, by having a number of smaller charges, the vibrations generated by the blast were far less than those created by one single blast using 200 kg of explosives — an important consideration given the number of buildings nearby. Secondly, by using five delays the blasts could be used to pull the building down away from the World Trade Centre. This was done over a period of 1.5 seconds moving back towards the World Trade Centre. The actual date for the blast was decided seven weeks in advance, because a variety of different government departments were involved and had to give permissions before the building could be demolished. Other considerations like events at the Exhibition Centre also had to be taken into account. “Once the date was picked it couldn’t be changed,” says Green. “This was because there were so many agencies involved. There were planning and co-ordination meetings with Dubai Police, Civil Defence, DEWA, Etisalat, Dubai Projects Office, The Ruler’s Office and the World Trade Centre,” he adds. Before the blast date all the services within the building had to be terminated at a safe distance. In case there was a problem, teams from the various utility providers were on site during the blast, along with Civil Defence and the police. On the blast day, a 180 m exclusion zone was set all the way round the site and people were evacuated from the nearby bungalows and office buildings, including the World Trade Centre. In some cases — as was the case with a few of the nearby embassies — security staff had to remain on the premises. This did not pose a problem since the exclusion zone was set to provide a safety cushion. This meant that if someone had decided to be stupid enough to walk towards the hotel, it would leave enough time for the explosives team to halt the detonation. With the blast now complete, a period of eight weeks will follow for the huge clear up operation. This involves the removal of the rubble from the blast and the building’s foundations. Once this work is finished, the site will then be handed over to Turner International. A total of 377 luxury apartments will be built on the site once it is clear. They will be configured as twin towers abutting each other to form an L-shaped development alongside the World Trade Centre. One tower will be 40 storeys high, and the second 30 storeys. Both will have basement parking. “We plan to start work immediately after the clean up operation. An award will be made for an earth retention system along the side of the World Trade Centre ramp before that,” explains Roger Softly, project manager for Turner International. “We expect to start construction work in May and a completion date has been set for 15th November 2007,” he adds. ||**||

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