An explosive is a set of compounds or a mixture of chemicals that tend to rapidly spread and chemically transform, followed by the release of a certain amount of heat and gas formation. There are two groups of such substances:
- Pyrotechnics.
- Initiating, throwing, blasting.
Explosive charge is the amount of chemical or nuclear substances concentrated in a vessel (metal or plastic) with special sockets for explosives.
For peaceful purposes, charges are used to destroy barriers, dilapidated buildings, etc. When performing military tasks, such devices are used to destroy bridges, damage pavement, fragments of pits.
The most often subversive substance is pressed TNT in checkers. The latter serve for the further manufacture of charges according to the specified parameters.
Distinguished by shape:
- extended;
- cumulative;
- focused;
- curly.
Each form hasits purpose. For example, curly ones are used to undermine various structures. Consequently, the very shape and thickness of the substance are selected individually.
Basic parameters in the calculation of blasting
The essence of the calculation of explosive charges when planning demolition work or operations is the correct selection of their quantity, mass and correct location.
The volume of the affected medium directly depends on the excess pressure. Therefore, the entire calculation begins with the definition of this parameter:
Dp =p - p0.
In this case, p is the pressure at the front of the shock wave; p0 – atmospheric pressure.
The difference between these parameters depends on the distance between the explosives, the environment and the amount of charge.
The overpressure value is calculated in several stages: first, the estimated radius of the explosion is found, then, using the resulting number, the actual overpressure is determined.
Having received all the necessary data, you can preliminarily assess the degree of destruction of the object (complete, strong, medium or weak).
Detonation methods and charge components
Production of explosive charges takes place in production, and ready-made they go to the warehouse, and it is also possible to manufacture them immediately before use.
There are four ways to explode the charge:
- fire;
- chemical;
- mechanical;
- electric.
In the firstcase, an incendiary tube is used, which is used even for undermining under water. In the manufacture, a clamping device, a special rope, a detonator are used. Used to detonate both single and mass charges.
The electrical method of actuating an explosive charge is effective for detonating a whole group of charges at a certain time. Its manufacture requires a number of measuring instruments, a source of electricity and an electric detonator.
Features of undermining various elements
For each structure and volume of the element, the explosive substance is selected individually. For example:
- To undermine wooden structures, logs, beams, contact and non-contact charges of various forms are used. In this case, non-contact charges should only be concentrated.
- Steel and other metal structures can only be undermined by contact external elongated ones, and the explosive charge can also be concentrated or curly.
- Concrete and reinforced concrete structures are undermined by contact and non-contact external and internal charges.
Marking of concentrated charges
Each explosive charge package is marked with waterproof paint. For most stocks, the designations are standard and consist of:
- Product code (for example, SZ-1 stands for "concentrated charge").
- Next, 3 digits separated by a dash are indicated. Such numbersindicate the plant code, batch number and year of manufacture (in order from left to right).
- Below is the code of the explosive (for example, T - TNT). If the substance is educational, a long white stripe is affixed instead of marking.
Safety in the use of explosives and demolition operations
Only specially trained people are engaged in the manufacture and use of hazardous substances. Persons who come into contact with the listed substances should study safety precautions and follow the instructions given.
Commands are given in the following order:
- get ready (after this signal is given, the substance is prepared for ignition);
- fire (fire tube ignites);
- depart (on this command, you should immediately retire to a safe distance, even if ignition has not occurred);
- clear off (this signal is given after explosives and charges have been detonated or neutralized).
Important! During the operation for carrying out explosions, it is necessary to study in advance the margin of time for smoldering and burning of the substance.
