Techniques for Repair and Demolition
Demolition Practice in USA
From as early as 1940, demolition works in USA were taken up with extensive applications of mechanical contrivances (something artificial) and convenient improvisations. (Provide or construct from materials etc, which is not intended for the purpose). The impact of blows from a large-sized iron ball swung from mobile crane boom brought drawn multi-storeyed apartment buildings and old structures. With the area well cordoned, off, the rubble and debris together with the rising dust were tackled in such a way, that at no stage was there any depature form the main aim of containing the effects of the demolition within the boundary.
In course of time, more improvements came by, and a significant alternative developed around 1950 was the use of dynamite in a sophisticated arrangement, whereby the operation could be carried out instantaneously and with no risk to the adjacent buildings or disturbance to the neighbourhood. The term implosion referred to this new process, was synonymous with the phenomenon of an explosion that caused no scattening of material knocked off, but obsorbed them well within the extremists of the compound.
A world wide leader in the implosion business, Controlled Demolition Inc., USA is a pioneer in this technique applied to demolition. In the works of its president Loizure, 'it is delieate art of denoting explosives, in just the right places to make a building collapse about neatly into its footprint.' The company takes justifiable pride that it has leveled about 7000 structures till date.
It is therefore, not a wonder that its services have been hired recently in Scuttle. The project here attracted the attention, of not only professional, but every citizen around, including the die-hard, who could not tolerate the removal of any historic landmark.
Following the changing needs of the metropolis, and the American predilection for newness, something befitting the city's huge arena, called 'Kingdome', looked incongruous.
This large indoor stadium was a multipurpose facility built in 1936 and served as the venue for all kinds of sports events, athletic meets, public functions and even music concerts. But the authorities decided on its demolition, to pave way for a modern open air starlium.
The Implosion Technique
The unique 'Kingdome' structure was a circular building with a strong, light roof only 5' thick and spanning 670.
It was so strong that it could endure a earthquake, and take on two feet of snow on its top, it can be seen that breaking such a dome needed all the ingenuity and the expensive of the contracting company, which had to wind. 1 miles of detonation cord through the structure, that was expected to light up like a lightening, flash followed by the sound of explosions.
. The day chosen for the demolition was a Sunday and nearly a week earlier. It is needless to add how much pre-panning and preparation had gone into this colossal scheme before actually putting into action the actual detonation. The entire series of operations formed five distinct stages from the preliminary phase, until the final explosion.
ü Stripping the Dome : Removing of roof surfacing pieces and insulation and exposing only the concrete. Stripping of AC systems fully. Other ramp demotion and removing lower level seating outfit, leaving concrete supports like beams and cnume.
ü Rotecting Neighbourhood : Wrapping nearby buildings with cushioning material, creating protective walls and berms around the site, and finally cottoning off (circle of police) the demolition area
ü Arranging Detonation Points: Drilling about 6000 holes of 1.5 feet diameter and 5 to 6 feet deep in the ribs of the roof and supporting columns. Packing the holes with a pre-calculated measure of explosives and fixing a time delay circuit. Wrapping 10000 ft of detonation cord to connect all the explosive points.
ü Topping Up: As a last phase, providing a thin top layer of the explosive material, and a hand denotation cord together with a fuse. This completed al the arrangements.
ü Explosion: As the cord was ignited, the fuse got set off, starting explosions in a controlled, progressive way at different intervals. The rubble from the lowest section got spread out in berms across the floor. This helped to absorb to some extent the impact from falling debris of the upper levels.
ü A great Feat: The destruction of 'Kingdome', an architectural beauty was a great engineering love loads, increased wheel loads, installations of heavy machined in demolition technology.