General information about the explosion and combustion processes. Explosion: shock wave actions and damaging factors What are explosions classification

Explodes within 0.0001 seconds releasing 1.470 calories of heat and approx. 700 liters of gas. Cm. Explosives.

The article reproduced the text from the Small Soviet Encyclopedia.

Explosion, the process of releasing a large amount of energy in a limited amount in a short period of time. As a result of vacuum, the substance that fills the volume in which energy is released turns into a highly heated gas with very high pressure. This gas exerts great force on environment causing it to move. An explosion in a solid medium is accompanied by its destruction and crushing.

The movement generated by the explosion, in which there is a sharp increase in pressure, density and temperature of the medium, is called blast wave. The blast wave front propagates through the medium at high speed, as a result of which the area covered by the movement expands rapidly. The occurrence of a blast wave is a characteristic consequence of V. in various media. If there is no medium, that is, an explosion occurs in a vacuum, the energy of V. is converted into the kinetic energy of V. products flying in all directions at high speed. V. produces a mechanical effect on objects located on at various distances from location B. As the distance from the explosion site, the mechanical effect of the blast wave weakens. The distances at which blast waves create the same impact force at V. of different energies increase in proportion to the cube root of the energy of V. Proportionally to the same value, the time interval for the impact of the blast wave increases.

Different kinds of explosions are different physical nature source of energy and how to release it. Typical examples of explosives are explosions of chemical explosives. Explosives have the ability for rapid chemical decomposition, in which the energy of intermolecular bonds is released in the form of heat. Explosives are characterized by an increase in the rate of chemical decomposition with increasing temperature. At a relatively low temperature, chemical decomposition proceeds very slowly, so that the explosive may not undergo a noticeable change in its state for a long time. In this case, a thermal equilibrium is established between the explosive and the environment, in which continuously released small amounts of heat are removed outside the substance through heat conduction. If conditions are created under which the released heat does not have time to be removed outside the explosive, then due to an increase in temperature, a self-accelerating process of chemical decomposition develops, which is called thermal decomposition. Due to the fact that heat is removed through the outer surface of the explosive, and its release occurs in the entire volume of the substance, thermal equilibrium can also be disturbed with an increase in the total mass of the explosive. This circumstance is taken into account when storing explosives.

Another process for the implementation of the explosion is possible, in which the chemical transformation propagates through the explosive successively from layer to layer in the form of a wave. The leading edge of such a wave moving at high speed is shock wave- a sharp (jump-like) transition of a substance from its initial state to a state with very high pressure and temperature. The explosive material, compressed by the shock wave, is in a state in which chemical decomposition proceeds very quickly. As a result, the region in which energy is released is concentrated in a thin layer adjacent to the surface. shock wave. The release of energy ensures that the high pressure in the shock wave is maintained at a constant level. The process of chemical transformation of an explosive, which is introduced by a shock wave and is accompanied by a rapid release of energy, is called detonation. Detonation waves propagate through the explosive at a very high speed, always exceeding the speed of sound in the original substance. For example, detonation wave velocities in solid explosives are several km/sec. A ton of solid explosive can be converted in this way into a dense gas with very high pressure in 10 -4 seconds. The pressure in the resulting gases reaches several hundred thousand atmospheres. The effect of a chemical explosive explosion can be enhanced in a specific direction by the application of specially shaped explosive charges (see below). Cumulative effect).

Explosions associated with more fundamental transformations of substances include nuclear explosions. In a nuclear explosion, the atomic nuclei of the original substance are converted into the nuclei of other elements, which is accompanied by the release of binding energy elementary particles(protons and neutrons), which are part of atomic nucleus. Nuclear war is based on the ability of certain isotopes of the heavy elements of uranium or plutonium to undergo fission, in which the nuclei of the original substance decay to form nuclei of lighter elements. In the fission of all the nuclei contained in 50 g of uranium or plutonium, the same amount of energy is released as in the detonation of 1000 tons of trinitrotoluene. This comparison shows that a nuclear transformation is capable of producing V. of enormous force. The fission of the nucleus of an atom of uranium or plutonium can occur as a result of the capture of one neutron by the nucleus. It is essential that as a result of fission several new neutrons are produced, each of which can cause the fission of other nuclei. As a result, the number of divisions will increase very quickly (according to the law of geometric progression). If we assume that with each fission event the number of neutrons capable of causing the fission of other nuclei doubles, then in less than 90 fission events such a number of neutrons is formed that is sufficient to fission the nuclei contained in 100 kg of uranium or plutonium. The time required for the division of this amount of matter will be ~10 -6 sec. Such a self-accelerating process is called a chain reaction (cf. Nuclear chain reactions). In reality, not all neutrons produced in fission cause the fission of other nuclei. If a total fissile matter is small, then most of the neutrons will go beyond the matter without causing fission. A fissile substance always has a small amount of free neutrons, however, a chain reaction develops only when the number of newly formed neutrons exceeds the number of neutrons that do not produce fission. Such conditions are created when the mass of the fissile material exceeds the so-called critical mass. V. occurs when the individual parts of the fissile material (the mass of each part is less than the critical one) are quickly combined into a single whole with a total mass that exceeds the critical mass, or during strong compression, which reduces the surface area of the substance and thereby reduces the number of neutrons escaping. To create such conditions, V. is usually used as a chemical explosive.

There is another type of nuclear reaction - the reaction of the fusion of light nuclei, accompanied by the release of a large amount of energy. The repulsive forces of the same electric charges (all nuclei have a positive electric charge) prevent the fusion reaction, therefore, for an effective nuclear transformation of this type, nuclei must have high energy. Such conditions can be created by heating substances to very high temperatures. In this regard, the fusion process, which proceeds at high temperature, is called thermonuclear reaction. During the fusion of deuterium nuclei (an isotope of hydrogen ²H), almost 3 times more energy is released than during the fission of the same mass of uranium. The temperature required for fusion is reached in a nuclear explosion of uranium or plutonium. Thus, if a fissile substance and hydrogen isotopes are placed in the same device, a fusion reaction can be carried out, the result of which will be V. of enormous force. In addition to a powerful blast wave, a nuclear explosion is accompanied by intense emission of light and penetrating radiation (see Fig. Damaging factors of a nuclear explosion).

In the types of explosions described above, the released energy was initially contained in the form of molecular or nuclear bond energy in matter. There are wind turbines in which the released energy is supplied from an external source. An example of such a voltage is a powerful electric discharge in any medium. Electrical energy in the discharge gap is released in the form of heat, turning the medium into an ionized gas with high pressure and temperature. A similar phenomenon occurs when a powerful electric current along a metal conductor, if the current strength is sufficient to quickly turn the metal conductor into steam. The phenomenon of V. also occurs when a substance is exposed to focused laser radiation (see. Laser). As one of the types of explosion, one can consider the process of rapid release of energy, which occurs as a result of the sudden destruction of the shell that held the gas with high pressure (for example, the explosion of a cylinder with compressed gas). V. can occur during the collision of solid bodies moving towards each other at high speed. On collision kinetic energy bodies are transformed into heat as a result of the propagation of a powerful shock wave through the substance that occurs at the moment of collision. The velocities of the relative approach of solid bodies, necessary for the substance to completely turn into vapor as a result of a collision, are measured in tens of kilometers per second, and the pressures developing in this case amount to millions of atmospheres.

Many different phenomena occur in nature, which are accompanied by V. Powerful electrical discharges in the atmosphere during a thunderstorm (lightning), sudden volcanic eruption, large meteorites are examples of different types of V. As a result of the fall Tunguska meteorite () V. occurred, equivalent in terms of the amount of energy released V. ~ 10 7 tons of trinitrotoluene. Apparently, even more energy was released as a result of the explosion of the Krakatoa volcano ().

Huge explosions are chromospheric flares in the sun. The energy released during such flashes reaches ~10 17 J (for comparison, we point out that at V. 10 6 tons of trinitrotoluene, an energy equal to 4.2·10 15 J would be released).

The nature of giant explosions occurring in outer space are flares new stars. During flashes, apparently within a few hours, an energy of 10 38 -10 39 J is released. Such energy is emitted by the Sun in 10-100 thousand years. Finally, even more gigantic V., going far beyond the limits of human imagination, are flashes supernovae, at which the released energy reaches ~ 10 43 J, and V. in the nuclei of a number of galaxies, the energy estimate of which leads to ~ 10 50 J.

Explosions of chemical explosives are used as one of the main means of destruction. They have great destructive power nuclear explosions. Explosion of one nuclear bomb can be equivalent in energy to V. tens of million tons of chemical explosive.

Explosions have found wide peaceful application in scientific research and in industry. V. allowed to achieve significant progress in the study of the properties of gases, liquids and solids at high pressures and temperatures (see. High pressure). The study of explosions plays an important role in the development of the physics of nonequilibrium processes, which studies the phenomena of mass, momentum and energy transfer in various media, mechanisms phase transitions substances, the kinetics of chemical reactions, etc. Under the influence of V., such states of substances can be achieved that are inaccessible with other methods of research. Powerful compression of the channel of an electric discharge by means of a chemical explosive makes it possible to obtain, within a short period of time, magnetic fields huge tension [up to 1.1 Ha/m (up to 14 million Oe), see A magnetic field. The intense emission of light during the V. of a chemical explosive in a gas can be used to excite an optical quantum generator (laser). Under the action of high pressure, which is created during the detonation of an explosive, explosive stamping, explosive welding and explosive hardening of metals are carried out.

The experimental study of blasting consists in measuring the velocities of propagation of explosive waves and the velocities of the movement of matter, measuring rapidly changing pressure, the distributions of density, intensity, and spectral composition of electromagnetic and other types of radiation emitted during blasting. These data make it possible to obtain information about the speed of various processes, accompanying V., and determine the total amount of released energy. The pressure and density of matter in a shock wave are connected by certain relationships with the velocity of the shock wave and the velocity of the matter. This circumstance makes it possible, for example, to calculate pressures and densities on the basis of velocity measurements in those cases when their direct measurement is inaccessible for some reason. To measure the main parameters that characterize the state and speed of movement of the medium, various sensors are used that convert a certain type of impact into an electrical signal, which is recorded using oscilloscope or other recording device. Modern electronic equipment makes it possible to register phenomena occurring during time intervals of ~ 10 -11 sec. Measurements of the intensity and spectral composition of light radiation using special photocells and spectrographs serve as a source of information about the temperature of a substance. High-speed photography, which can be carried out at a speed of up to 10 9 frames per second, is widely used for recording the phenomena that accompany shooting.

In laboratory studies of shock waves in gases, a special device is often used - a shock tube (see Fig. Aerodynamic tube). A shock wave in such a pipe is created as a result of the rapid destruction of the membrane separating the high-pressure and low-pressure gases (this process can be regarded as the simplest type of winding). When studying waves in shock tubes, interferometers and penumbral optical installations are effectively used, the operation of which is based on a change in the refractive index of a gas due to a change in its density.

Explosive waves propagating over long distances from their place of origin serve as a source of information about the structure of the atmosphere and the inner layers of the Earth. Waves at very large distances from the place of V. are recorded by highly sensitive equipment, which makes it possible to record pressure fluctuations in the air up to 10 -6 atmospheres (0.1 n / m²) or soil movements ~ 10 -9 m.

Literature:

Sadovsky M.A., Mechanical action of air shock waves of an explosion according to experimental data, in the collection: Physics of the explosion, No. 1, M., 1952;
Baum F. A., Stanyukovich K. P. and Shekhter B. I., Fizika vzryva, M., 1959;
Andreev K. K. and Belyaev A. F., Theory of explosives, M., 1960:
Pokrovsky G. I., Explosion, M., 1964;
Lyakhov G. M., Fundamentals of explosion dynamics in soils and liquid media, M., 1964;
Dokuchaev M. M., Rodionov V. N., Romashov A. N., Ejection explosion, M., 1963:
Cole R., Underwater explosions, trans. from English, M., 1950;
Underground nuclear explosions, trans. from English, M., 1962;
Action nuclear weapons, per. from English, M., 1960;
Gorbatsky V. G., space explosions, M., 1967;
Dubovik A.S., Photographic registration of fast processes, M., 1964.

K. E. Gubkin.

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physical explosion - caused by a change in the physical state of matter. chemical explosion- is caused by the rapid chemical transformation of substances, in which the potential chemical energy is converted into thermal and kinetic energy of expanding explosion products. Emergency, this is an explosion that occurred as a result of a violation of production technology, errors of maintenance personnel, or errors made during the design.

Explosive "medical environment" - is a part of the room in which an explosive atmosphere can occur in small concentrations and only for a short time due to the use of medical gases, anesthetics, skin cleansers or disinfectants.

The main damaging factors in an explosion are an air shock wave, fragmentation fields, propelling effects of surrounding objects, a thermal factor (high temperature and flame), exposure to toxic explosion and combustion products, and a psychogenic factor.

Explosive injury occurs when the impact of an explosion on people in a confined space or in an open area, as a rule, is characterized by open and closed wounds, injuries, contusion, hemorrhages, including in the internal organs of a person, ruptures of the eardrums, bone fractures, skin burns and respiratory tract, asphyxiation or poisoning, post-traumatic stress disorder.

Explosions at industrial enterprises: deformation, destruction of technological equipment, power systems and transport lines, collapse of structures and fragments of premises, leakage of toxic compounds and poisonous substances. Explosive technological lines:

Grain elevators: dust,

Mills: flour,

Chemical plants: hydrocarbons, oxidizers. In addition to oxygen, oxygen-containing compounds (perchlorate, saltpeter, gunpowder, thermite) are oxidizing agents, some chemical elements(phosphorus, bromine).

Filling stations and oil refineries: vapors and aerosols of hydrocarbons.

The distance of damage on the example of the explosion of a tanker is 5 tons. Baiker U. 1995) I. Thermal damage from the impact of a fireball: - up to 45 m. Incompatible with life, - up to 95 m. Burns of the III degree. - up to 145 m. Burns of II degree. - up to 150 m. Burns I st. - up to 240 m. Burns of the retina. II. Mechanical damage by a shock wave: - up to 55 m. Incompatible with life, - up to 95 m. Head injury, barotrauma of the lungs and gastrointestinal tract, - up to 140 m. Rupture of eardrums.

The blast shock wave can cause great loss of life and destruction of structures. The size of the affected areas depends on the power of the explosion. The extent to which secondary measures are used depends on the likelihood of a dangerous explosive atmosphere occurring. Hazardous areas are divided into different zones according to the time- and local-dependent probability of the presence of a dangerous explosive atmosphere.

Zone 0. An area in which there is a permanent, frequent or long-term dangerous explosive environment and where a dangerous concentration of dust, aerosols or vapors can be formed. Such as mills, dryers, mixers, silos, production facilities using fuel, product pipelines, supply pipes, etc.

Zone 1. The area in which, due to the concentration of combustible vapors, aerosols, swirling, deposited dust, an accidental occurrence of a dangerous explosive atmosphere can be expected. Close proximity to loading hatches; at the sites of filling or unloading equipment; in areas with fragile equipment or lines made of glass, ceramics, etc.;

Zone 2. An area where a dangerous explosive atmosphere can be expected, but very rarely and for a short time.

Dust explosion risk assessment

In the immediate vicinity of devices containing dust from which it can leak, settle and accumulate in dangerous concentrations (mills). In an explosion of dust with a low concentration in the medium, the head compression wave of the explosion can cause a vortex motion of the deposited dust, which gives a high concentration of combustible material. The risk of explosion of a dust mixture is much less than that of a gas, steam or mist. Zones of accidents during volumetric explosions can cover large areas. Accident on a gas pipeline in Bashkiria (June 1989) Q2 km. Dead-871, wounded 339 people. The problem of saving people after an explosion and a fire was that almost all emergency medical equipment burned out in a flame, and about improvised means in such cases, victims and rescuers are almost forgotten.

The main criteria determining the magnitude of sanitary losses are: the type of explosive device, the power of the explosion, the location of the explosion and the time of day. Depending on the number and localization of damage can be isolated, multiple and combined. According to the severity of injuries: light, moderate, severe and extremely severe. Table 4.1. the degree of damage to people depending on the magnitude of excess pressure is presented.

Upon contact with an explosive device, explosive destruction of the outer parts of the body or destruction (detachment) of limb segments occurs. The wound process in this case has a number of features: - Acute massive blood loss and shock; - Contusions of the lungs and heart; - Traumatic endotoxicosis; - The combined nature of the impact of damaging factors.

An explosion is understood as a very rapid release of energy as a result of physical, chemical or nuclear changes in the explosive substance "BB".

During an explosion, the initial substance or its transformation products always expand, as a result of which a very high pressure arises, causing the destruction and displacement of the environment.

The initial types of explosion energy can be physical, chemical and nuclear.

The types of physical explosions include: 1) kinetic (meteorite); 2) thermal (explosion of a boiler, autoclave); 3) electrical (lightning, electric charge: 4) elastic compression (earthquake, freezing of water in a tank, rupture of a car tire, etc.).

A chemical explosion is a pulsed exothermic chemical process of rearrangement (decomposition) of molecules of solid or liquid explosives with their transformation into molecules of explosive gases. This creates a hotbed of high pressure and releases a large amount of heat. Only certain substances called explosives have the ability to explode. The process of decomposition of explosives can occur relatively slowly - by burning, when layer-by-layer heating of explosives due to thermal conductivity is observed, and relatively quickly - by means of detonation (supersonic shock-wave decomposition of a chemical, explosive).

If the speed of the first process is measured in centimeters, sometimes hundreds of meters per second (for black powder - 400 m / s), then during detonation the decomposition rate of explosives is measured in thousands of meters per second (from 1 to 9 thousand m / s). The huge destructive effect of the explosion is due to the fact that the energy during the explosion is divided very quickly. So, for example, an explosion of 1 kg of explosive occurs in 1-2 hundred-thousandths of a second. The burning and detonation rates of various explosives are strictly constant. The features of impulse decomposition of explosives are the basis for their division into propellant (gunpowder), initiating and blasting (crushing). Depending on the strength and nature of the external impact, some explosives can either burn or detonate.

The rate of release of explosive gases during the decomposition of explosives is much higher than the rate of their dispersion. A mass of 1 kg of explosive forms about 500-1000 liters of explosive gases. Initially, the entire volume of gases formed approaches the volume of the charge, which explains the occurrence of a giant jump in pressure and temperature. If during combustion the pressure of gases can reach several hundred megapascals (under the condition of a closed space), then during detonation it is 20.0 - 30.0 GPa (2.5 million atm.) At a temperature of several tens of thousands of degrees Celsius. The pressure of explosive detonation products in a cumulative formation can reach 100.0–200.0 GPa (10–20 million atm.) at travel speeds of up to 17.7 km/sec. No medium can withstand such pressures. Any solid object in contact with the explosive begins to crush. E.L. Bakin, I.F. Aleshina Inspection of the scene of crimes committed by explosion, and some aspects of forensic investigations of seized material evidence. Toolkit. Moscow 2001

The fundamental difference in the mechanism of propagation of an explosion and combustion lies in the different rates of these processes: the rate of combustion is always less than the rate of propagation of sound in a given substance; the explosion speed exceeds the speed of sound in the explosive charge. Therefore, the explosion and combustion of explosives have different effects on the environment. The products of combustion carry out the throwing of bodies in the direction of least resistance, and the explosion causes destruction and penetration of barriers in contact with the charge or located close to it in all directions.

The burning rate depends to a large extent on external conditions, and primarily on the pressure of the environment. With an increase in the latter, the combustion rate increases, while combustion can in some cases turn into detonation.

Up to a certain distance, explosive gases retain their destructive properties due to high speeds and pressures. Then their movement quickly slows down (inversely proportional to the cube of the distance traveled) and they stop their destructive action. There is evidence that the piston action of gases occurs until the volume has reached 2000 - 4000 times the volume of the charge (G.I. Pokrovsky, 1980). However, the disturbance of the environment continues and is mainly of a shock-wave nature (Nechaev E.A., Gritsanov A.I., Fomin N.F., Minnulin I.P., 1994).

From an energetic point of view, an explosion is characterized by the release of a significant amount of energy in a very short time and in a limited space. Part of the energy of the explosion is initially wasted on breaking the shell of the ammunition (transition into the kinetic energy of the fragments). About 30-40% of the energy of the formed gases is spent on the formation of a shock wave (areas of compression and tension of the environment with their propagation from the center of the explosion), light and thermal radiation, and the movement of environmental elements

In the process of explosion, the following stages are distinguished: external impulse; detonation; external effect (explosion work).

The foregoing opens the way to understanding the essence, purpose, structure and content of the forensic theory of explosives and explosives as instruments of crime, as well as those created taking into account the provisions of forensic investigation techniques.

This doctrine belongs to the class of private forensic theories. Each of two parts: general and special. Two levels are meant: two subsystems of one system of scientific knowledge. The general part is usually called the general theory (in the context of a given knowledge system). In a special part as

elements include private theories as subsystems related to certain components, aspects, objective-subject area of the corresponding system.

The forensic doctrine of explosives and explosives as instruments of crime is no exception in this regard. It also consists of a general and a special part. The general part of this doctrine (its general theory) can be defined as a generalized typical information model containing, in the form of general, basic provisions, knowledge that is equally significant for all cases of investigation in cases where explosives and explosives appear as crime weapons (definition of key concepts of the doctrine, information about the types and features of explosives and VU, traces associated with them, various classifications of certain objects, information about their information potential, principles, methods, means of detection, fixation, seizure, research of carriers and sources of criminally relevant information, forms, possibilities, directions and ways of its use in pre-trial criminal procedure).

As for the special part, it can be defined as a system of theories, each of which, also being a typical information model, but at a lower level compared to the general theory of the doctrine in question, includes knowledge about the specifics certain types and varieties of the objects under study and the originality of activities for their involvement in the criminal process of other information in the conditions of typical investigative situations and solutions to the search and cognitive tasks caused by them.

In other words, the general theory should give an idea of the general characteristics of the entire class of studied and constructed objects, and each particular theory reflects the originality of the corresponding type of objects, everything that makes up its specificity as an element of a class (system).

The object of the forensic doctrine of explosives and explosives as instruments of crime is criminal activity associated with the manufacture, theft, storage, transportation, sale and use of explosives and explosives, the consequences of their use for criminal purposes, traces that occur at all stages of the mechanism of criminal activity, as well as the activities of law enforcement agencies to detect, fix, inspect, seize, preserve, study these objects, obtain, verify and implement the forensically significant information contained in them at the stage of initiating a criminal case and during the preliminary investigation.

The subject of this doctrine are the patterns underlying the mentioned processes, as well as criminal and forensic activities. Under the rules in this case are understood each time with the necessity of repeating under certain conditions stable connections between the elements of a criminal event cognized in criminal cases and the same type of connection that exists between the elements of the investigation as a cognitive system.

The circle of regularities also includes external links of both systems, that is, links between the investigation system and the crime system (for example, a natural connection between the type and volume of explosives and the power of the explosion, its consequences and traces that have arisen, between the nature and scale of the harmful consequences of the explosion and the solution of the issue of the number of investigators who need to be involved in the inspection of the scene, between the quality of the work of the investigator in the preparation of a forensic explosive examination and the effectiveness of the expert study).

Important from a scientific, practical and didactic point of view is the question of the place of the forensic doctrine of explosives and explosives as instruments of crime in a broader system of scientific knowledge. No less significant is the receipt of correct answers to questions about its connections and correlations with other forensic theories (teachings), primarily with related, close, related ones.

“Private forensic theories are interconnected by many connections, relationships, mutual transitions,” wrote R. S. Belkin, supplementing this idea with the provisions that private forensic theories can completely or partially coincide with both objects and objects, “because they can to study various manifestations of the same objective regularities related to the subject of forensic science as a whole, in various subject areas” Belkin R. S. Course of forensic science. M., 1997. T. 2. S. 22, 24.

The question of the place of the doctrine in question does not have an unambiguous answer. It all depends on s. what point of view to approach its decision. The first approach, as it were, lies on the surface, since it is most directly related to the functional significance of explosives and explosives in the mechanism of the crimes we are studying, being included in this mechanism as an instrument for committing them.

From this it follows that the forensic doctrine of explosives and VUs is integral part a broader system of forensic knowledge, which is called the forensic theory of the instrument of crime (forensic tool science). As part of latest system it occupies an intermediate link, on the one hand, entering a certain part of the forensic doctrine of substances used as instruments of crime, since explosives are one of the types of substances used for criminal purposes in this capacity (along with poisonous, potent and other substances ).

Thus, there is reason to consider forensic explosions as an integral, complex, relatively independent subsystem of forensics, the object-subject area of which includes all types of explosions of a criminal nature, all types of intentional and reckless criminal acts, directly or indirectly related to real and potential, objectively possible and imaginary explosions, in the mechanisms of committing and trace formation of which various types of explosives and explosive devices (or information about them) function, regardless of whether the latter perform the function of a crime weapon or another function.

The main applied value of forensic explosives as a private forensic theory, in our opinion, is to optimize the development processes various types general and private methods of investigating the crimes discussed in this work, improving their quality level and practical impact.

The theoretical basis for the creation of a general methodology for investigating this group of crimes is laid by a common part, General Theory of Forensic Explosives. The same theories, which as components are included in a special part of forensic explosives, play the role of theoretical premises, theoretical constructions that contribute to the creation of less general and particular methods of investigation.

Thus, "forensic explosives" can be interpreted in a broad and narrow sense. In wide semantic meaning this concept characterizes a fairly large group of crimes and activities to identify and investigate them. The central place here is occupied by crimes related to the use of explosives and VU as a weapon of crime. In a narrow sense, only one of the subsystems of scientific knowledge in this area can be designated as forensic explosives, that is, the theory and methodology for detecting and investigating crimes related to the use of explosives and explosives as a tool for achieving criminal goals.

All VV by state of aggregation are divided into: 1) gaseous (hydrogen and oxygen, methane and oxygen); 2) dusty (coal, flour, textile, etc. dust mixed with air or oxygen); 3) liquid (nitroglycerin); 4) solid (trotyl, melinite, hexogen, plastite): 5) aerosol (drops of oil, gasoline, etc. in the air); 6) mixtures.

There is the following technical classification of explosives: 1) primary, or initiating; 2) secondary, or blasting (crushing); 3) throwing, or gunpowder; 4) pyrotechnic mixtures.

Initiating explosives are especially sensitive to mechanical and thermal influences, therefore they explode very easily. Usually they are used to excite (initiate) the explosion of secondary explosives, gunpowder and pyrotechnic compositions. For these purposes, they are used in igniter primers and detonator caps. The most commonly used are lead azide, lead trinitroresorcinate (THPC, lead styphnate), mercury fulminate, etc.

High explosives are the main class of explosives used for loading mines, shells, grenades, bombs and for blasting. The most common explosive of this type is TNT (trinitrotoluene, tol). Its detonation speed is 6700 m/sec. The industry produces TNT in the form of blocks weighing 75, 200 and 400 g. Milinite (picric acid) is produced in the form of blocks. The substances of increased power include tetritol, hexogen, octogen, heating elements, plastite. Reduced power substances are: ammonium nitrate, ammonal and ammotol (a mixture of TNT and ammonium nitrate), dynamon. Old explosives: nitroglycerin (explosives based on nitroglycerin, for example, explosive jelly), dynamite, pyroxylin (see Appendix No. 1).

Propellants, which include black powder (75% potassium nitrate, 15% coal, 10% sulfur), smokeless powders (pyroxylin and nitroglycerin), usually do not detonate, but burn in parallel layers. Their burning rate (flash) is 10-100 times less than the detonation time (under certain conditions they can detonate). They are used as "expelling charges" in various devices for both military and civilian purposes, as well as shells, small arms bullets and as rocket fuel.

Pyrotechnic compositions are mechanical mixtures intended for equipping products in order to obtain various effects. The main explosive transformation of mixtures is combustion, however, some compositions can detonate. They consist of combustible materials, oxidizing agents, binders and various additives. In the military and other industries, lighting, photo-illumination, tracer, signal, incendiary, jamming, smoke, thermite and other pyrotechnic compositions are used. The main components of pyrotechnic compositions are: fuel, oxidizing agent and cementing agent.

To excite the detonation of a secondary (blasting) explosive, a significant external impact is required in the form of a very strong impact (for example, for a thick block, the initiating impact velocity must be at least 1500-2000 m/s). Such a blow is carried out during the explosion of a detonator, and sometimes an auxiliary charge, which requires a much smaller blow or a little warming up for its initiation.

The following are used as detonators:

1. capsules - igniters;
2. blasting caps;
3. capsules for hand grenades;
4. electric detonators and electric igniters;
5. various fuses (for mines, shells, bombs).

A special group is made up of igniting means of initiating an explosion: 1) igniter (beakford) cord - OSH; 2) detonating cord - DSh (with a detonation speed of 7000-8000 m/s).

Purposeful use of the energy of the explosion and its damaging factors, including for criminal purposes, is realized through the use of explosive devices (VU).

An explosive device is understood as a specially manufactured device that has a set of features indicating its intended use and suitability for the production of an explosion.

The design of large explosive devices (VU) includes: 1) the main explosive charge; 2) auxiliary charge; 3) detonator. The explosion of such a device is usually accompanied by the destruction of the outer layers of the explosive, followed by the expansion of its unreacted particles and fragments. This phenomenon reduces the power and efficiency of the explosion.

To increase the mass of the explosive entering the detonation, increase the power of the explosion and its damaging effect, the design of the explosive device is supplemented with a shell. The shell is designed to restrain the scattering of explosive pieces for some time and prolong the process of its detonation. The stronger the shell, the stronger the explosion.

The second purpose of the shell is the formation of massive fragments with high kinetic energy and a pronounced damaging effect (sometimes military forensic doctors call them high-energy fragments. To streamline this process, a shell with pre-made notches (semi-finished striking elements) is used. In addition, the VU shell may include yourself and ready-made "lethal" elements (balls, arrows, nails, pieces of metal, etc.).

Among explosive devices, explosive devices with a cumulative effect constitute a special group. It consists in the defeat (penetration) of objects not due to the kinetic energy of the projectile, but as a result of the "instantaneous" concentrated action of a high-speed cumulative jet formed when the cumulative funnel is compressed by an explosive charge explosion. This is typical mainly for directional ammunition such as special cumulative anti-tank projectiles and grenades.

According to their power, explosive devices are divided into:

1. High power explosive device (large and medium air bombs, artillery shells of 76 mm or more, anti-tank mines, land mines and other similar explosive devices with a TNT equivalent of at least 250 g);
2. VU of medium power (grenades (Fig. 4), anti-personnel mines, shots for hand grenade launchers, explosive checkers, artillery shells from 27 to 75 mm and other similar explosive devices with a TNT equivalent from 100 to 200-250 g);
3. VU of low power (fuses, detonators, fuses (Fig. 5), shells up to 27 mm and other similar explosive devices with TNT equivalent up to 50-100 g E. L. Bakin, I. F. Aleshina. Inspection of the scene at crimes committed by means of an explosion and some aspects of forensic investigations of seized physical evidence.

Along with military explosive devices, various pyrotechnic and imitation means can be used for criminal purposes. Some of them (for example, IM-82, IM-85, IM-120 imitation cartridges and SHIRAS artillery projectile imitation cartridges) are loaded with explosive charges and have a powerful destructive effect during the explosion.

The class of explosive devices of industrial production also includes the so-called civilian products and special means containing explosives in their design (Key and Impulse products, Zarya and Flame flash and sound grenades) and are used mainly to penetrate the premises and temporary psychophysiological impact on the offender.

Home-made VUs (IEDs) are devices in the design of which there is at least one home-made element, or those in the manufacture of which non-industrial ad-hoc assembly is used. There are a large number of types of IEDs that differ in the principle of operation, the level of destruction during an explosion, and the material used in the construction. In this regard, only an approximate classification of IEDs is possible, according to which they can be divided into the following types: IEDs according to the type of hand grenade; IED by the type of object mine (intended for mining an object); IEDs of the type of booby trap (there is a camouflage case); IED by the type of explosive projectile with an explosive; IED by the type of explosive package.

It is no coincidence that in the first chapter I examined in detail the concepts of an explosion, explosives, explosives, explosives, and their classification. And only after that is given a methodology for examining the scene of crimes committed by explosion. In special literature for investigators, the section on the basics of the concepts of forensic explosives is often omitted or given in a very concise, schematic way. Under such conditions, it is impossible to teach the person conducting the inspection how to competently search, correctly record, and take measures to seize material evidence. In practice, we have repeatedly encountered situations when investigators, starting to inspect the scene of an incident, without special knowledge, believe that a specialist should “know, search and prompt them” everything.

From Wikipedia, the free encyclopedia

Explosion- a fast-flowing physical or physico-chemical process that takes place with a significant release of energy in a small volume in a short period of time and leads to shock, vibration and thermal effects on the environment due to the high-speed expansion of explosion products. An explosion in a solid medium causes destruction and crushing.

In physics and technology, the term "explosion" is used in different senses: in physics, a necessary condition for an explosion is the presence of a shock wave, in technology, to classify a process as an explosion, the presence of a shock wave is not necessary, but there is a threat of destruction of equipment and buildings. In technology, to a large extent, the term "explosion" is associated with processes occurring inside closed vessels and rooms, which, with an excessive increase in pressure, can collapse even in the absence of shock waves. In the technique for external explosions without the formation of shock waves, compression waves and the impact of a fireball are considered. :9 In the absence of shock waves, the hallmark of an explosion is the sound effect of the pressure wave. :104 In technology, in addition to explosions and detonations, pops are also emitted. :5

In the legal literature, the term "criminal explosion" is widely used - an explosion that causes material damage, harm to the health and life of people, the interests of society, as well as an explosion that can cause the death of a person.

Explosion action

The consequences of the explosion of a steam locomotive, 1911

The explosion products are usually gases with high pressure and temperature, which, when expanding, are capable of performing mechanical work and causing destruction of other objects. In addition to gases, explosion products may also contain finely dispersed solid particles. The destructive effect of the explosion is caused by high pressure and the formation of a shock wave. The effect of the explosion can be enhanced by cumulative effects.

The effect of a shock wave on objects depends on their characteristics. The destruction of capital buildings depends on the momentum of the explosion. For example, when a shock wave acts on a brick wall, it will begin to tilt. During the action of the shock wave, the slope will be insignificant. However, if after the action of the shock wave the wall will tilt by inertia, then it will collapse. If the object is rigid, firmly fixed and has a small mass, then it will have time to change its shape under the action of the explosion impulse and will resist the action of the shock wave, as a force applied constantly. In this case, the destruction will depend not on the momentum, but on the pressure caused by the shock wave. :37

Energy sources

According to the origin of the released energy, the following types of explosions are distinguished:

Chemical explosions of explosives - due to energy chemical bonds starting materials.
Explosions of containers under pressure (gas cylinders, steam boilers, pipelines) - due to the energy of compressed gas or superheated liquid. These include, in particular:
- Explosions during pressure release in superheated liquids.
- Explosions when two liquids are mixed, the temperature of one of which is much higher than the boiling point of the other.
Nuclear explosions - due to the energy released in nuclear reactions.
Electrical explosions (for example, during a thunderstorm).
Volcanic explosions.
Explosions on impact space bodies, for example, when meteorites fall on the surface of the planet.
Explosions caused by gravitational collapse (explosions of supernovae, etc.).

chemical explosions

Unanimous opinion on which chemical processes should be considered an explosion, does not exist. This is due to the fact that high-speed processes can proceed in the form of detonation or deflagration (slow combustion). Detonation differs from combustion in that chemical reactions and the process of energy release proceed with the formation of a shock wave in the reacting substance, and the involvement of new portions of the explosive in chemical reaction occurs at the front of the shock wave, and not by heat conduction and diffusion, as in slow combustion. The difference between the mechanisms of energy and substance transfer affects the rate of processes and the results of their action on the environment, however, in practice, there are a variety of combinations of these processes and transitions from combustion to detonation and vice versa. In this regard, various fast processes are usually referred to as chemical explosions without specifying their nature.

A chemical explosion of non-condensed substances differs from combustion in that combustion occurs when a combustible mixture is formed during the combustion itself. :36

There is a more rigid approach to the definition of a chemical explosion as exclusively detonation. It necessarily follows from this condition that during a chemical explosion accompanied by a redox reaction (combustion), the burning substance and the oxidizer must be mixed, otherwise the reaction rate will be limited by the rate of the oxidizer delivery process, and this process, as a rule, has a diffusion character. For example, natural gas burns slowly in domestic stove burners because oxygen slowly enters the combustion area by diffusion. However, if you mix the gas with air, it will explode from a small spark - a volumetric explosion. There are very few examples of chemical explosions that are not caused by oxidation/reduction, such as the reaction of finely dispersed phosphorus(V) oxide with water, but it can also be considered as

Explosive injury occurs when the impact of an explosion on people in a confined space or in an open area, as a rule, is characterized by open and closed wounds, trauma, contusion, hemorrhages, including in the internal organs of a person, ruptures of the eardrums, bone fractures, skin burns and respiratory tract, asphyxiation or poisoning, post-traumatic stress disorder.