Explosive technology

EXPLOSIVE TECHNOLOGY (EN: blasting technology; DE: Schießtechnologie; FR: technique du tir, technique de l'explosion; ES: tecnica de explosion; RU: взрывная технология) is the deliberate destruction, movement, modification of the structure and shape of the natural (rocks, ice, wood) and artificial (metals, plastics, concrete, and so on) materials, which is performed on the account of the energy from the explosion. There are used as the energy sources mostly the chemical explosive substances, sometimes also the pressurized air, electric discharge, and so on.(Figure # 1) The scheme for the development of the foundation pit using the explosion

The general information. In case of the explosive technology, the control over the process is performed: using the dosing of the energy within the charge of the explosive substance; using the adjustment of the amplitude and duration of the pulse of the explosion on the account of the change of the aggregate state of the explosive substance, or on the account of the usage of the charges with the damping aerial interval; using the geometry of the placement of the system of the charges within the space; using the different methods and sequence for the initiation of the individual charges with the purpose of their rational interaction. The major peculiarities of the explosive technology are the combination within the charge of the explosive substance of the functions of the energy source and of the working body, the speed of the flow of the process, and the high powers. The explosive technology is characterized by the increased danger (the emergence of the aerial shock wave, of the seismic impact, the dispersion of the medium, which is being destructed, the forming of the harmful gaseous products from the detonation), which fact requires the compliance with the special safety rules (see the "Blasting works" article).

(Рисунок № 2) Конструкция заряда / (Figure # 2) The structure of the charge(Figure # 2) The structure of the charge

The field of the usage. The major quantities of the usage of the explosive technology are accounted for the mining craft and construction, where, with the help of the explosion, are conducted the crushing of the materials (mainly of the massifs of the rocks), their compaction, directional movement, the study of the structure of the Earth's crust, the mining-exploratory works at the deposits of the useful minerals, namely, the penetration of the trenches, exploratory pits, adits, mine shafts, and so on. The explosive technology has been successfully introduced for the processing of the metals (for welding, stamping, strengthening, and so on), and is used within many other fields of the technology (the energy of the explosive substance is driving into action the tool, which permits us to split or cut cables, to punch holes, to rivet, to engrave onto the metals). Using the explosion, they extinguish the forest and peat fires, and they scatter the organic fertilizers onto the fields. Under the action of the shock wave, there are polymerized the ionic and radical monomers, and also the monomers, which are not susceptible to polymerization using other methods (for example, diphenylacetylene).

The crushing of the materials using the explosion. During the crushing, as a rule, they use the combination of the local and general modes for the work of the explosion (the breaking of the rocks within the open-pit mines and underground mines, the penetration of the mine workings, the destruction of the foundations, and so on); less often, there is used only the local mode (the breaking of the metallic structures, of the reinforced concrete structures, the felling of the trees, and so on). The mode for the work of the explosion is regulated using the change of the ratio between the amount of the energy within the charge of the explosive substance, and the distancing of this charge deeper from the exposed surface; if this ratio is extremely small, then, on the account of the brisant action, there take place the grinding, compression, and compaction of the substance, with the forming of the camouflet cavity. In case of the certain increasing of this ratio, there is achieved the crushing of the rock up to the exposed surface without the dispersion; in case of the further increasing of this ratio, the degree of the crushing increases, but yet more there are growing the expenditures of the energy for the movement of the pieces, there are increasing the losses of the energy within the aerial shock wave. The major method for the blasting of the rocks during the opencast and underground development is the borehole breaking, less often they use the methods for the blasthole charges, cauldron charge, and chamber charges.

(Figure # 3) The scheme for the positioning of the charges during the crushing of the ice

During the conducting of the underground mine workings, and for the extraction of the dimension stone, they use the blasthole charges. The intensification of the crushing of the rocks is achieved by the usage of the rational schemes for the short-delay blasting, by the usage of the charges with the aerial intervals and intra-borehole slowdowns, by the preserving of the retaining wall, which is made of the previously blasted rock. Within the mines, which are hazardous because of gas and dust, they use the shaking and flameless blasting. For the increasing of the stability of the mine workings, and for the nearing of the contour of the mine working to the designed contour, they use the contour blasting. The significant quantities of the blasting are accounted for the loosening of the rocky rocks during the blasting of the blasthole, borehole, and chamber charges, for the forming of the profiled excavations for the engineering built structures and buildings (see the Figure # 1), for the railways and automotive highways, for the cable lines and pipelines, for the canals of the hydraulic electric power plants, and so on.

(Figure # 4) The positioning of the charges during the breaking of the beam

There occupy the special place the construction of the underwater trenches, and the dredging works, which are usually conducted with the help of the attached, blasthole, and borehole charges. With the help of the explosion within the rocky rocks, they form the excavations for the pylons of the electric transmission lines (see the Figure # 2), for the sunk wells, and so on.

The significant quantities of the works are performed for the explosive crushing of the oversized rocks and boulders. Using the blasting, they destruct the ice cover (see the Figure # 3), large floating ice floes, and liquidate the traffic congestions of the ice.

They crush the metal, using the method of the external (see the Figure # 4) or blasthole charges, with the usage of the highly brisant explosive substances.

The explosive technology is used for the crushing of the slags, and of the refractory masonry, during the current and extensive repairs of the blast furnaces, and during the emergency response. They widely use the explosive collapsing of the buildings and industrial built structures, using the simultaneous explosion of the combination of the small blasthole charges of the explosive substances, which are destructing the lower part of the walls throughout the entire perimeter of the built structure, which should be collapsed (see the Figure # 5).

(Figure # 5) The positioning of the charges during the blasting of the built structures

During the period of the completion of the construction works at the hydraulic engineering facilities, they destruct the partitions, which are made of the soil or rocky rock, using the explosion for the loosening. They effectively use the explosive method for the loosening of the moraine soils (the cemented sands with the inclusions of the boulders), and of the frozen soils (in case of the depth of the freezing of more than 0.8-1 metres). They crush the frozen soils, using the blasthole, borehole, cauldron, small chamber (see the Figure # 6), and slit charges.

Using the explosion, they loosen the caked materials, namely, the table salt, copper sulfate, pitch, and others. There is prohibited the loosening of the materials (for example, of the saltpetre), within which there may emerge the detonation. The loosening is conducted within the stacks, warehouse spaces, and open wagons.

The compaction of the compressible rocks using the explosion. Within the plastic rocks (for example, clays), the dynamic explosive load leads to their non-reversible compression. This process proceeds mostly thanks to the repacking of the particles of the skeleton. The practical usage of the explosive compaction for the non-rocky rocks is very diverse. With the help of the explosion, which is compressing the soil, they construct the mine workings without the extraction of the rock. They use the obtained cavities within the bowels of the Earth as the exploratory pits for the exploration of the deposits, as the mine shafts for the ventilation of the shallow underground mines, as the storage facilities for the petroleum and gas, as the containers for the burial of the harmful industrial wastes, and so on. For the forming of the cylindrical mine working, they drill the borehole along the axis of this mine working, fill this borehole with the explosive substances throughout the entire length, and explode this borehole. They obtain the mine working of the elliptical shape using the explosion of the two elongated charges, which are situated in the parallel manner. For the forming of the spherical cavity, they explode the concentrated charge. During the construction of the roads through the peat bogs, they perform with the help of the explosion the seating of the mounds onto the mineral bottom of the swamps. At the moment of the explosion, the quagmire under the sandy backfill is pushed to the sides, and the mound settles onto the mineral bottom.

(Figure # 6) The widening of the excavations within the frozen soils

The explosive compaction of the subsiding and water-saturated uncemented soils is the effective means for the increasing of the strength of the foundations for the built structures. The liquefaction of the soil proceeds because of the disappearance of the significant portion of the contacts between the particles of the skeleton after the passage of the compression wave. After the certain time (hours, days) after the liquefaction by the explosion, there starts the consolidation of the solid particles, and the compaction of the soil. The water is displaced from the sediment, which is formed during this process, and this sediment acquires the stable structure. Using these properties of the soils, they construct the earthen built structures within the swampy regions.

During the compacting of the subsiding soils using the explosion (the sandy loams, loams, pebbles, and so on), they use the methods for the deep, superficial, and underwater explosions (see the Figure # 7).

(Figure # 7) The installation of the hanging charges

With the help of the explosion, they change the filtrational properties of the soils, which fact is especially important for the irrigation facilities (for example, the decreasing by several times of the speed of the filtration within the river beds, which are formed of the sandy loams, loams, and pebbles). On the account of the loosening of the soils while using the explosion, there is increased their permeability, which fact is used for the restoration of the water yield from the aquifers through the boreholes, and for the planting of the soil layer. For the restoration of the water yield from the non-pressurized aquifers, and for the increasing of the productivity of the low-yield boreholes, they use the explosive torpedoes, which are manufactured of the detonating cord within the waterproof sheath (see the "Torpedoing of the boreholes" article). For the thermal-gaseous-chemical processing of the productive layers, they burn the powder charges. The cracks, which have been formed by the explosion, assist the regulation of the content of the water within the soil.

They use the directional movement of the rocks using the explosion mostly for the forming of the dams, partitions, water reservoirs, canals, trenches, and mounds. The energy of the explosion is used for the movement of the significant amounts of the rocks, the direction and distance of which are determined by the mass of the charges of the explosive substances, by their structure, by the geometry of the placement within the massif, which is being blasted, by the time of the slowdown, and so on. On the account of the gravitational acceleration, and of the pressure of the rock, which is being collapsed, there is achieved the high density of the core within the future built structure, which is ensuring its mechanical and filtrational stability and durability. They distinguish the explosions for the ejection and for the dumping (more comprehensively, see within the "Directional explosion" article).

(Figure # 8) The scheme of the explosive welding

The processing of the metals using the explosion. The pulsing explosive loads permit us to realize during the processing of the metals the physical phenomena, which are not used within the traditional technologies of the welding, stamping, strengthening, cutting, and punching of the products. Using the explosion, they weld many homogeneous and heterogenous metals, in this case they obtain the compounds of the metals and alloys, which may not be welded together using the known methods (aluminium with the stainless steel, copper with lead, and so on). The high-speed collision of the solid bodies during the welding using the explosion is accompanied by the process of the wave forming on the surface of the contact. During the collision of the plates, which are being welded together (at the certain angle), the surface is cleaned on the account of the fact, that the thin layer of the particles, which are contaminating the surface, is carried away by the emerging gas stream. This fact improves the quality of the welded seam. Within the simplest scheme for the welding of the metals using the explosion, they install two metallic plates at the certain distance one from each other, with the determined inclination (see the Figure # 8).

They sturdily fix the bottom plate onto the support, and place the layer of the explosive substance (sometimes with some inert underlayer) onto the upper plate. During the welding using the explosion, the maximal micro-hardness is achieved not on the surface of the mutual impact, where usually proceeds the forming of the waves, but at the certain distance from the surface of the welded seam. They use the welding using the explosion for the connection of the flat, tubular, and rod-shaped parts, and also for the obtainment of the multi-layer materials and parts (for example, of the bearing sleeves, which are made of the bimetallic anti-friction copper alloys with the thin layer of the copper alloy), and of the composite materials with the alternation of the hard and soft layers.

(Figure # 9) The stamping of the cap

While using the explosion, there may be formed the products with the practically unlimited sizes. During the single operation, they conduct the stamping with the processing of the edges, with the punching of the holes, and so on. The usage of the energy of the explosion for the stamping has led to the significant modernization of the equipment, has permitted us to create the principally new methods for the processing of the metals (for example, the underwater stamping using the explosion). They usually place the workpiece onto the matrix, they fix the flange with the help of the clamping devices, and they place the charge of the explosive substance into the determined position above the workpiece (see the Figure # 9).

Then they lower the matrix with the charge and workpiece into the transmitting medium, and they explode the charge. Under the action of the shock wave, the workpiece starts to deform into the direction of the matrix. The explosion creates the high speeds of the loading and deformation of the metal, which is being stamped, which fact assists the improvement of the mechanical properties of this metal. With the help of the explosion, there may be obtained the parts of the complicated shape with the degree of the precision, which, in the series of cases, is not achievable for the usual methods; the connections of the metals possess the high sturdiness and the substantial advantages in comparison with the connections, which have been obtained using the usual methods.

The strengthening of the metals using the explosion proceeds during the propagation of the sufficiently strong shock waves within these metals. In one case, this fact is associated with the improvement of the crystal structure of the metals, while in the other case, this fact is associated with the enlargement of the defects of the crystal lattice of the brittle materials. Within the USSR, they use the explosion for the strengthening of the parts for the crushers, of the track links for the continuous tracks, of the teeth of the buckets for the excavators, and of other parts. The processing of the welded seams of the thin-walled shells, which are made of the high strength alloys, using the explosion, decreases the internal stress within the zone of the seam by many times, and increases the wear resistance. The explosive method is suitable for the pressing of the products, which are made of the metallic and non-metallic powders.

The high pressures during the explosion of the explosive substances are used within the industry for the cutting and punching of the sheet metal, thick plates and strips. This result is achieved during the punching of the holes using the explosion of the shaped charges, during the contact cutting with the help of the contour charges, during the cutting with the help of the sheet-shaped and cord-shaped explosive substances, which are attached onto the workpiece. For the obtainment of the holes within the sheet-shaped mechanical engineering parts and workpieces, they use the contour charges; during the forming of the holes within the bottoms, they usually use the concentrated charges of the spherical shape. It is possible to strengthen the local action of the explosion with the help of the shaped charge. Using the explosion of the charges of the explosive substance, they cut the moving cold and hot metal within the productive line of the rolling mills.

The historical outline. The first known practical usage of the energy of the explosion for the destruction of the massif of the rocks has been the blasting of the underground gunpowder charges, which were the prototype for the chamber charges of the explosive substance. The earliest mention about the underground gunpowder charges belongs to the time of the siege of the Belgrade city (1440). Within Russia, the gunpowder is known since the 1389, the first powerful underground charges have been exploded during the 1552 during the siege of the Kazan city. The underground-mine warfare was successfully conducted by the Russians during the 1581-82 near the Pskov city during the siege of this city by Stefan Batory, and during the 1610 within the Smolensk city. During the 1548-72, the Russian specialist Nikolai Tarlo has cleared the fairway of the Neman river, using the explosion of the gunpowder charges. The history of the usage of the explosion within the mining craft was started since the February 8, 1627, when the Tyrolean person K. Baidel has successfully used the gunpowder charges within the blastholes for the penetration of the Upper Beaver adit at the "Banská Štiavnica" ore mine within Slovakia. With the help of this method, there were conducted the underground mining works within Austria, Sweden, Germany, and since the 1670, within other countries of Europe. During the 1687, there has been performed for the first time the tamping in the form of the wooden bung.

By the end of the 17th century, the drilling machines allowed to drill the blastholes to the depth of 1-1.5 metres, and this fact has led to the increase of the charge of the explosive substance, and to the usage of the clay tamping instead of the bung tamping. The usage of the gunpowder for the crushing of the rocks within the ore mines (the so-named gunpowder-firing works) has terminated the primitive fire, pickaxe, and wedge work for the separation of the rocky rocks from the massif. Within the mining industry of Russia, the gunpowder was initially used for the extraction of the ores, while the coal was destructed using the pickaxe and pick. During the start of the 19th century, the breaking with the help of the gunpowder charges was distributed into the underground mineral coal mines. There assisted the development of the blasting method for the breaking of the rocks the invention of the electric method for the explosion of the charges of the explosive substance by the Russian scientist P. L. Schilling (1812), and the invention of the safety fuse by the the British scientist William Bickford (1831). The large-scale explosions with the help of the so-named giant mines (the chamber charges with the mass of the tens of tonnes of the explosive substance) for the breaking of the building stone within the quarries have been used for the first time during the 2nd half of the 19th century. There were broken from the massif simultaneously up to 100 thousand cubic metres of the rocky rocks, which were used for the strengthening of the shores and for the construction of the breakwaters within the harbours of the Mediterranean sea. Within the Friuli region, during the 1851 and 1857, there have been exploded the gunpowder chamber charges with the total mass of 32 tonnes of the gunpowder, which event has allowed to break 100 thousand cubic metres of the rock. The perfecting of the explosive technology was tightly associated with the development of the new explosive su bstances and means for the drilling.

During the start of the 60-ies, the gunpowder was replaced with the new explosive substances (primarily with the liquid nitroglycerin), the charging with which was dangerous because of its high sensitivity and high technological difficulties (especially within the cracked rocks). The significant expansion of the quantities of the blasting works within the rocks is associated with the invention of the copper blasting cap with the mercury fulminate during the 1865 within Russia (D. I. Andrievskiy), and of the dynamite during the 1867 within Sweden (A. Nobel). Since the 1871, the dynamite was used within Russia for the extraction of the zinc ores and mineral coal. Thanks to the usage of the dynamite, there has become possible the construction of the first large tunnels within the Alps: the Mont Cenis Tunnel (12 kilometres), the Saint Gotthard Tunnel (15 kilometres), and others. During the 1876-85, within the USA, within the New York harbour, there have been conducted the large-scale blasting works (including the underwater works) for the destroying of the reefs. During one of the explosions, the total mass of the explosive substances within the 3680 boreholes has amounted to 23.6 tonnes, with the average consumption of 0.47 kilograms per cubic metre.

During the 1879, the French scientist Mesen has proposed as the means for the explosion the cord with the core of the grained guncotton, which was the prototype for the modern detonating cord. During the end of the 19th century, at the productive petroleum fields within Russia, there have been conducted the blasting works within the boreholes (the torpedoing), with the purpose of the increasing of the petroleum recovery from the layers. During the 1912, at the "Champion" productive field, the engineer G. Nevsky has used for the first time the explosive method for the increasing of the extraction of petroleum. The increasing of the intensity and scale of the mining production during the start of the 20th century, especially with the development of the opencast method for the development, has required the increasing of the depth of the embedment and of the size of the charges of the explosive substance; for this purpose, they widened the bottom part of the deep (5-6 metres) blasthol es, using the explosions of the small charges, till the imparting to this blasthole the shape of the cauldron with the voluminous capacity of several tens of kilograms (the so-named cauldron charges, which have been used during the 1913 during the extraction of the iron ores within the Krivoy Rog region). During this period, at the open-pit mines within the USA, for the placement of the charges of the explosive substances, they started to use the boreholes with the diameter of 150-190 millimetres, with the depth of 10-15 metres, which were drilled using the cable-churn rigs.

During the 1913, within the USA, there has been proposed to study the structure of the Earth's crust with the help of the reflected seismic waves, which have been excited using the explosion; during the 1919, for the same purposes, L. Mintrop (Germany) has proposed to use the refracted waves (see the "Seismic exploration" article). During the 1924, within the Kirkenes city (Norway), there has been performed one of the first large explosions of the chamber charge with the mass of 50 tonnes, using which there has been broken 350 thousand tonnes of the ore. During the 1924, within the Grand County (USA), with the help of the explosion, there has been extinguished for the first time the fire at the gas borehole. During the 1930, within the region of the Maikop city, using the explosion of the charge of the explosive substance, there has been extinguished the fire at the petroleum borehole.

The metamorphosis of the explosive technology into the multi-branch scientific-technological direction is associated with the names of the Soviet scientists M. Ya. Sukharevsky, V. A. Assonov, and others, who, during the start of the 20-ies, have organized within Russia the conducting of the large quantities of the blasting works for the uprooting of the stumps, for the deep loosening of the soil, for the drying of the swamps, for the excavation of the soils for the foundations, for the extraction of the building stone, for the destruction of the large metallic products, for the destroying of the rapids on the rivers, and others. The growth of the scale of the blasting works within the USSR was restrained by the imperfection of the drilling equipment and its insufficient quantity, thus, since the 1926, at the open-pit mines within the USSR, there is used the method for the chamber charges with the placement of the large quantity of the explosive substance (10 tonnes and more) withi n the underground mine working (chamber). The concentrated charges within the chambers, under the name of the "mine" charges, have also got the wide distribution for the underground development of the thick depositions of the strong ores within the Krivoy Rog region (the breaking, the seating of the pillars, and the collapse of the ceilings). The perfecting of the drilling rigs has allowed to increase the diameter and depth of the boreholes at the open-pit mines, to transition from the concentrated chamber charges to the borehole charges. Within the USSR, this method has been used for the first time during the 1927 during the development of the strong granites at the construction of the Dnepr Hydraulic Electric Power Plant, and has got the rapid distribution at the open-pit mines; since the 1935, the method for the borehole charges was used during the underground development of the thick ore deposits (the apatites of the Kola peninsula, and others).

During the 30-ies, within the USSR, for the first time within the worldwide practice, using the explosions of the charges for the ejection, there were conducted the capital trenches for the unsealing of the deposits of the useful minerals at the Podolsk open-pit mine, Korkino open-pit coal mine, and so on, there were built the canals, and foundation pits (N. N. Bogorodskiy, G. P. Demidyuk, N. N. Paporotskiy, A. N. Samodurov, F. V. Selevtsev, and others). During the 1930-40-ies, within the USSR, there were conducted approximately 200 explosions with the usage of the large chamber charges; for this purpose, there have been performed the works for the calculation of the seismically safe distances from the place of the explosion (M. A. Sadovskiy). Since the 1945, at the open-pit mines within the USA, there was introduced the short-delay explosion of the charges of the explosive substance (which has been performed within the USSR for the first time by K. A. Berlin during the 1934 durin g the penetration of the vertical mine shaft), and there were created the electric detonators with the millisecond slowdowns. During the 50-60-ies, within the USSR, there have been developed the fundamentals for the explosive stamping of the metals (R. V. Pikhtovnikov, Yu. S. Navagin, O. D. Antonenkov). During the 1954, within the USA, there has been researched and patented by V. Allen and G. Abrahamson (1964) the process for the explosive welding; this phenomenon has been discovered independently during the 1961 within the USSR (A. A. Deribas, and others).

During the middle of the 50-ies, the powdered industrial explosive substances were replaced within the USSR with the simplest explosive substances, which are not containing the explosive components, and somewhat later with the water-filled explosive substances, which fact has allowed to start the mechanization of the labour-intensive processes of the explosive technologies, namely, the charging and tamping (see the "Charging machine", and the "Tamping machine" articles). During the 60-ies, there have been performed the fundamental works for the usage of the aerial intervals within the borehole and chamber charges (N. V. Melnikov, L. N. Marchenko), for the study and introduction of the short-delay explosion (G. I. Pokrovskiy, G. M. Kitach, S. A. Davydov, and others); there was introduced the blasting onto the non-removed rock mass (the buffered blasting), the blasting of the high benches at the open-pit mines, and the short-delay explosion of the parts of the distributed charges within the borehole. During the 1930-60-ies, within the USSR, there were developed the scientific fundamentals, and were conducted the practical works for the compaction of the soils, using the explosion, for the building purposes (N. M. Syty, A. A. Vovk, G. K. Akutin, and others), there has been obtained the scientific substantiation, and have been introduced the systems of the flat charges of the explosive substances (M. A. Lavrentiev, V. M. Kuznetsov, A. A. Chernigovskiy, and others), there was developed the modern methodology for the large-scale (including unique) directional explosions (M. A. Lavrentiev, G. I. Pokrovskiy, M. A. Sadovskiy, N. V. Melnikov, M. M. Dokuchaev, and others). The further usage of the massed explosions for the construction of the large open-pit mines, hyd ro-technical built structures, and anti-mudflow dams, has allowed to develop the rational methods for the calculation of the major parameters, to organize the works for the practical performing of such explosions (F. A. Avdeev, and others).