Planning and analysis
Planning a demolition with explosives means mostly studying the building and the context in which the intervention will take place.
For greater information download the PDF document (1,8 Mb) of the special one dedicated from the review of field “RECYCLING” dell’abbattimento del Palazzo Condominiale di via Fratelli Garrone di 80 appartamenti a Mirafiori Sud, Torino.
A plan regarding a demolition with explosives develops with particular attention to the following matters:
- quantity of explosives and the use of electrical or [detonici] primers;
- explosive charging mode;
- planning of the [piano di tiro] and circuits installation and [collegamenti di tiro] mode;
- time of the flown one;
- [tiro] circuits protection system;
- dimensioning of the weakenings.
For greater information download the PDF document (1,6 Mb) of the special one dedicated from the review of field “QUARRY and CONTRUCTIONS” of the demolition of the Railway Bridge up river Stura to Pessineto: Mezzenile (TO).
One of the earliest phases of the planning is the valuation of the most likely fall down model according to the structure and the context:
Implosion or vertical fall
Demolitions through explosives are often mentally associated to implosion due to the many spectacular scenes transmitted by television. In fact this method is much less used than thought, because,often, tall buildings present a rigid structure that does not permit a vertical fall.
During the implosion the building falls down (actually there is a large amount of little lateral falls), leaving the ruins in the middle.
Demolizione di capannone a Concordia
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Overturning or lateral fall
The overturning is the most used technique, even if the need of space means of course larger scrapyards. When the structure to be demolished has vertical development, we have to make it fall towards a prefixed direction through a cut at its base.
Folding of a water tower
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Obviously, the practical actuation of the intervention has decisive importance in every work.
According to the designed plan it is possible to correctly place the explosives in the previously prepared holes.
These operations have to be executed by licensed [fochini] with proved experience in order to avoid any problem in the charging phase.
The obvious disturbs due to the detonation of the explosives can be previewed and reduced. There are:
- Rubble projection
- [sovrappressioni] and tremors
The rubble projection is estimable basing on simple ballistic [formulas], adapted to the structural conditions. From the results we estimate a safety distance, that is always enlarged in order to have more safety.
There are, anyway, practical solutions to this problem, which allow an almost total amortization of the rubble, such as metallic nets or [geotessuti], ([schermature]).These solutions have a containment power of almost 100%.
Tremors and sound are consequences of essentially two factors: the detonation and above all the fall of the mass of the building.
We can reduce also these effects by fractioning the times of energy inlet into the sole, reducing the injected power, and trough the [letti di caduta].
The problem of dust is partially contained by the use of water, which is constantly directed towards the falling structure to lower it as fast as possible.