The most dangerous from the point of view of stability will be underground workings laid along tectonic structures, where longitudinal and diagonal cracks predominate

Currently, the majority of vein deposits of precious metals with various mining and geological conditions are exposed to underground mining in deep zones where the massif is under a stress-strain state, in the presence of tectonic disturbances and faults.
the most dangerous from the point of view of stability will be underground workings laid along tectonic structures, where longitudinal and diagonal cracks predominate.
increased fracture in the vicinity of tectonic disturbances is characterized by a decrease in the strength characteristics of ore and host rocks, prone to sudden collapse.
When conducting excavations in the thickness of rocks around them, stress redistribution occurs, during which the rocks tend to move to a new state of equilibrium and undergo certain deformations, the so-called rock pressure.
Under the influence of rock pressure, rocks in the roof of a horizontal or inclined mine are initially deflected. Then cracks form in them, at first imperceptible, and then increasing and branching. As the cracks expand, there is a violation of the connection between the rock particles, the loss of its individual pieces and the collapse of the roof.
Mechanical stresses in the rocks around the workings increase with the depth of their location, i.e. the stress state of the rock mass increases. As a result, the so-called dynamic manifestations of rock pressure are observed in the form of firing rocks, tremors and rock blows, which are dangerous when conducting underground operations. A similar situation is currently observed when excavating workings at a depth of 300-320m in the Zarmitan mine.
The efficiency and safety of mining operations largely depend on the nature of the manifestation of rock pressure and on the ability to manage it.
The nature and magnitude of the rock pressure, in addition to the physicomechanical properties of the rocks and the depth of the mine from the surface, also depend on the shape and size of its cross section and many other factors. Moreover, the shape and surface of the wall of the mine is the main manifestation factor for the dynamic manifestation of rock pressure.
The vaulted sectional shape is read most susceptible to rock pressure in horizontal and inclined workings. However, it will not always be possible to obtain this shape, especially when driving workings through complex structural massifs, represented by heterogeneous rocks with unevenly developed cracks with drilling and blasting preparation and preserving cross-sectional shapes over time. To obtain and maintain the shape of the arch and the given dimensions of the workings in specific conditions, it is necessary to erect a support or develop a technological method that, perceiving rock pressure, prevents collapse and sudden firing of rocks, which is an urgent research task.
The author of the dissertation set a goal “Development of technological schemes for driving horizontal and inclined underground mine workings that impede further collapse or sudden firing of rocks”
The idea of ​​his work is that, resistance to collapse or sudden firing of rocks on horizontal and inclined underground mine workings increases with a vaulted cross-sectional shape, the creation of which is based on a comprehensive study of the mining conditions of specific deposits, analysis of best practices on the method of mining and economic assessment.
To achieve the goal, the author formulated the following research objectives:
- analysis of the current state of the issue. The purpose and objectives of the study;
- the study of gas-dynamic processes in the charging chamber during the explosion of hole charges of various designs;
- study of the formation of a directional split in the explosion of the explosive contour charges;
- Development of a scheme and methodology for determining the parameters of contour blasting;
- industrial tests of contour blasting during mining;
- Economic evaluation of technological schemes of contour blasting during mining.
Research methodology - analysis of existing trends in contour blasting technology during mine workings, scientific and technical generalization of literature and practice data, analytical calculations. The use of graphoanalytical methods for design, graphic and mathematical modeling, the application of computer programming and graphics.
The scientific novelty of the work is as follows:
- it was established that the duration of the maximum peak loads when the detonation wave acts on the well wall is 0.05-0.15 ms, which is 1-2 orders of magnitude less than the characteristic time of the increase in radial stresses to a maximum in the middle zone of the explosion in rock formations;
- It was experimentally established that during the explosion of low-explosive explosives in contour charges, the radius of intense crack formation decreases by 30-40%, while the growth of the main crack and its size in relation to regular blasting decrease by 10%;
- a methodology has been developed for calculating the parameters of drilling and blasting operations during mining, taking into account the depth of mining, taking into account the basic properties of rocks and allowing to increase the safety of the massif;
- experimentally investigated the formation and propagation of main cracks and crack formation zones depending on the properties of the explosive and the charge structure at the quasistatic stage of the explosion. The experimental results showed that the relative radius of the charge for charges without stemming is 0.96, and for charges with sand-clay and shaped stemming 0.97 and 0.985, respectively;
- on the basis of numerical simulation, the duration of the impact on the rock mass of detonation products at the quasistatic stage is established. The values ​​of the impulse of the explosion were obtained for various designs of charges, which are 9 ms, 11 ms, 13 ms, respectively, for charges without stemming, with sand-clay and shaped stemming;
- industrial approbation of the proposed parameters of explosive bombardment and charge structures confirmed the calculated data and assumptions when solving problems of increasing the safety of the marginal part of the massif during mining at deep horizons. According to the results of experimental explosions, it was found:
The surface of the outcrop of the outcrop of the mine is quite flat, without bumps and visible cracks. For the entire length of the insertion, the residual surface of the hole is traced, which indicates the completeness of detonation of the explosive and the uniform load of the rock mass by detonation products.
The depth of mining is taken into account by an additional increase in specific consumption, and the quality of contour blasting with a radius of rock destruction taking into account the effect of additional destruction at the quasistatic stage of the explosion.
Scientific and practical significance of the research results:
- a technological scheme and methodology have been developed that allow specific conditions to determine the rational parameters of contour blasting,
The research results can be used in the practical activities of underground mines and in the educational process of mountain universities

Yangisi:
Currently, the majority of vein deposits of precious metals with various mining and geological conditions are exposed to underground mining in deep zones where the massif is under a stress-strain state, in the presence of tectonic disturbances and faults.

the most dangerous from the point of view of stability will be underground workings laid along tectonic structures, where longitudinal and diagonal cracks predominate.
increased fracture in the vicinity of tectonic disturbances is characterized by a decrease in the strength characteristics of ore and host rocks, prone to sudden collapse.
When conducting excavations in the thickness of rocks around them, stress redistribution occurs, during which the rocks tend to move to a new state of equilibrium and undergo certain deformations, the so-called rock pressure.
Under the influence of rock pressure, rocks in the roof of a horizontal or inclined mine are initially deflected. Then cracks form in them, at first imperceptible, and then increasing and branching. As the cracks expand, there is a violation of the connection between the rock particles, the loss of its individual pieces and the collapse of the roof.
Mechanical stresses in the rocks around the workings increase with the depth of their location, i.e. the stress state of the rock mass increases. As a result, the so-called dynamic manifestations of rock pressure are observed in the form of firing rocks, tremors and rock blows, which are dangerous when conducting underground operations. A similar situation is currently observed when excavating workings at a depth of 300-320m in the Zarmitan mine.
The efficiency and safety of mining operations largely depend on the nature of the manifestation of rock pressure and on the ability to manage it.
The nature and magnitude of the rock pressure, in addition to the physicomechanical properties of the rocks and the depth of the mine from the surface, also depend on the shape and size of its cross section and many other factors. Moreover, the shape and surface of the wall of the mine is the main manifestation factor for the dynamic manifestation of rock pressure.
The vaulted sectional shape is read most susceptible to rock pressure in horizontal and inclined workings. However, it will not always be possible to obtain this shape, especially when driving workings through complex structural massifs, represented by heterogeneous rocks with unevenly developed cracks with drilling and blasting preparation and preserving cross-sectional shapes over time. To obtain and maintain the shape of the arch and the given dimensions of the workings in specific conditions, it is necessary to erect a support or develop a technological method that, perceiving rock pressure, prevents collapse and sudden firing of rocks, which is an urgent research task.