Considered are the thermodynamic conditions on the surfaces generated in coal cracks in the process of its destruction. It is shown that the temperature at the surface of cracks on the stage of destruction is comparable with the melting temperature of coal and ignition of methane. Ratios for the assessment of the development phase transitions on the surfaces of coal cracks. It is shown that the rate of methane in proportion to the total surface of the pieces of coal at de-struction. To reduce the amount of methane generation it is recommended to reduce the load on the breakage face.
About 30 % of the mountain weight extracted on rubble the enterprises, at explode and the subsequent mechanical crushing, the fraction less makes than5 mm(elimination) which practically does not find selling and litters an environment. The output of elimination is influenced essentially with detonation characteristics explosives.
Formation of longitudinal and volumetric waves in a vicinity of a cavity of the explosive chamber is investigated. By the received results the conclusion is made, that for an estimation of parameters of waves of pressure on walls of an explosive cavity the shock adiabatic curve of an elastic harbinger, because of affinity of adiabatic curves of an elastic harbinger and a wave of volumetric compression can be used.
The article studies dependences of rock strengths on the time of their stressing basing on the thermal-kinetic theory of strength. The main task of the research was to calculate thermo-kinetic features of rocks and, taking into account cleavage data, to build up calculation dependences and compare them with experimental results. As the result, indices of dynamic tensile (pull) and shear strengths have been received, which are necessary for subsequent calculation of parameters of drilling and blasting operations.
The influence of natural fractures and blocks of different categories and orders on the parameters of explosive fracture of rocks is considered. The results of calculations of the size of fracture zones during explosion in monolithic and fractured rocks, as well as the influence of natural fracturing and the thickness of spalling layers on the granulometric composition in the spalling zone are presented.
The efficiency of rock destruction by explosion of explosives also depends on the dissipation energy. When using explosives with different detonation characteristics, the dissipation energy changes significantly in the crushing zone, which in turn affects the overall destruction efficiency.
При разрушении скальных горных пород наиболее перспективным направлением является применение экологически чистых технологий с использованием электромагнитных полей, которые способны влиять на физическо-механическое состояние горной породы. Рассмотрен механизм разрушения скальных пород на основе учета естественных и наведенных трещин, прочности породы, структуры трещин и стадий разрушения, что позволяет определить эффективные режимы электромагнитного воздействия на различных технологических циклах отработки и снизить энергетические затраты.
A significant part of energy (up to 70%) in explosive destruction is irreversibly spent on heating of rock particles in the near zone and represents dissipative losses. The consequence of intensive dissipative processes is an increase in temperature and the development of induced microcracking in the medium deformed by the explosion. A significant fraction of energy remains in the explosion cavity in the form of internal energy of detonation products and can also be attributed to dissipative losses. Thus, only a part of the explosion energy is spent on the formation of mechanical disturbances. Therefore, when solving problems about the formation and propagation of stress waves, it is necessary to keep in mind the effects of energy dissipation.
The formation of the structure of the chipping zone can be investigated using the method proposed by B.V. Zamyshlyaev to determine the structure of the cavitation layer during explosion of explosives in water near the free surface. The method is based on the use of the laws of disintegration of an arbitrary discontinuity during the interaction of a stress wave with a free surface. As a result of the interaction, a shock wave will propagate in the air, and a rarefaction wave will propagate along the condensed medium from the interface toward the explosion chamber. The maximum tensile stress in the rarefaction wave is determined by the method of mirroring the explosion source with the introduction of an imaginary charge.
To calculate the parameters of drilling and blasting operations for explosive destruction of rocks, empirical dependences or relations based only on the action of stress waves are used. It is known, however, that at the quasi-static stage of the explosion there is additional destruction of rocks. It is manifested both in the secondary crushing of pieces in the fracture zone and in the increase in the size of this zone. Qualitatively, these effects are known and used, in particular, in the creation of various types of faces in the mouths of boreholes and wells, increasing the duration of the quasi-static stage of the explosion. However, the physical and mechanical processes of additional fracture at the quasi-static stage of the explosion have been studied much less than at the wave stage.
Explosive block blasting is one of the key operations in the technology of extraction of granite blocks in the production of natural stone facing materials. It provides both acceptable economic expenses at extraction of blocks, and the corresponding productivity of the extracting enterprise. The main requirement for such operations is to minimize the impact of blasting on cracking in the granite block.
Проблема обеспечения сохранности естественных кристаллов алмаза при разработке месторождений кимберлитов взрывным способом является весьма актуальной ...
В задаче о распространении волн напряжений при взрывах ВВ в конденсированных средах модель среды, замыкая систему уравнений движения, в значительной степени определяет способ ее решения ...
