Home – Home – Jornals – Fundamental and applied issues of mining 2021 number 2

A modular multi-channel seismic acquisition system for exploration in mines is developed. A brief description of the seismic station is given. Circuit design solutions providing a special explosion-proof level of protection PO (Ma) are proposed.

The results of monitoring man-induced seismic activity using Ermak-5 seismic control station in the mining area of the Kalinovskaya-Vostochnaya mine are considered. Places, intensity, and causes of seismic events recorded at the depth of coal seam mining and affecting the nearby residential areas are determined.

A method is proposed to control misalignment of boreholes drilled in parallel to one another for the purpose of stress measurement in rock mass. The method includes the analysis of displacements of the measurement hole boundary along different orientations of a strain gauge during step-by-step loading of the disturbance hole boundary. This method allows determining the angle of possible horizontal or vertical offset of axis connecting the hole centers. The calculated offset angles are compared with the actual tacheometric survey data on the center coordinates of holes.

A comparative analysis of strength characteristics of rocks in the thawed and frozen states for new pilot holes 309, 310 of kimberlite pipe Mir was carried out. The values of physical and mechanical characteristics under study are presented.

A multi-channel measuring and computing system consisting of four sensors was in operation at the open pit of Zarnitsa diamond pipe in 2019 and 2020. In 2019, intensive mining operations were carried out at the open pit. The sensors recorded dynamic changes in the width dimensions of fault zones. After temporary closing down of mining operations in the beginning of 2020, the widths of fault zones changed smoothly with positive and negative trends, which indicated an increase in the stress state of rock masses. These changes exceeded the values when mining operations were conducted. It is found that dynamic effects reduce the stress state of rock masses.

The algorithm for seismic tomography of coal-bearing solid mass is developed and embodied in software. It allows evaluating the type and parameters of geological disturbances. When seismic exploration is used, the type and characteristics of disturbances are determined by analyzing the distribution of deviations in kinematic, dynamic and spectral parameters of the wave field from their background values in the plane of extraction panel area under study.

Based on the results of mine geophysical surveys of coal pillars using the ANGEL-M system with the function of electrometric mine equipment and numerical modeling of the stress-strain state of a rock mass, an empirical dependence of the relative intensity and vertical stresses in pillars was obtained when mining thick coal seams. Design solutions for the prevention of geodynamic phenomena are developed using the stress index of the rock mass.

Propagation of a plane electromagnetic wave of the microwave range in a coal seam with hydraulic fracture is simulated. The coefficient of its reflection from the “coal-fracture with proppant” interface is calculated taking into account the variation of probing signal frequency and electromagnetic properties of the material filling the fracture.

The given research paper reviews tensed and deformed condition around the cavity, disposed on definite depth in resilient viscous-plastic quarter space under the dynamic pressure by the daylight surface. To solve the problem, it is necessary to construct mechanic-mathematical model using system in differential equations in private derivative first-order of hyperbolic type, which can be solved by the usage the numerical method of S. K. Godunov, named “gap disintegration”. The received numeric solving of the above mentioned task can be used in projecting and constructing the minefields, underground constructions and other objects.

According to the results of seismicity monitoring in Kuzbass, it is determined that the strongest seismic activations of the subsoil in the area of coal workings occur as short-term activations lasting one to two months. Similar activations occur more frequently at other objects. Induced seismicity in Mountain Shoriya is considered. The effect of partial synchronization of seismicity development was discovered at Kazsky, Sheregeshsky, and Tashtagolsky, mines located hundreds kilometers apart. No such synchronization is observed at open-pit and underground coal mines.

The results of influence exerted by technogenic and natural deformation effects on the resonance response in seismoacoustic and electromagnetic fields are presented and possibility of its use to control the stress-strain state in geotechnical systems is studied. This research aims at increasing the information level of the method for recording natural electromagnetic radiation to monitor the stress-strain state in railway tunnels. Experimental work is carried out to record electromagnetic radiation when electric trains passed the tunnels in areas with different engineering and geological conditions and depths.

The results of a numerical study of reservoir properties of coal samples containing fracture systems are presented. Coal thin polished specimens are used as a source of crack systems. The problem of fluid filtration in cracked coals is numerically solved by the finite element method. The influence of fracture system geometry on the filtration properties of geomedium is demonstrated.

Irreversible strain is believed to be formed under in-plane shears. Normal strain varies proportionally to a respective shear in directions perpendicular to shear planes. This approach makes it possible to consider fracturing and pore development without applying Kachanov - Rabotnov kinetic equation for damage. The model, based on the maximum shear stress and the exponential law, provided the grounds to solve the problems on strain and failure of an elastic-creeping body at the stages of nonstationary and stationary creep. Stresses, creep strains, fracture start time and complete failure time, as well as position of the fracture front and its development velocity at any time are determined for the structural elements under study.

It is shown that all rockburst-hazardous ore deposits in Russia are exposed to gravitational-tectonic stress state of rocks, in which the prevailing role is played by horizontal stresses due to mountain-forming processes in the Earth's crust exceeding the vertical stresses several times. These horizontal stresses are the main cause of dynamic rock pressure manifestations. It is shown that energy characteristics of dynamic phenomena in mines can be calculated by the formula for seismic moment in the earthquake source, since there is no difference in seismic occurrences both in natural processes and in mine seismicity. Based on the law of self-similarity of the seismic process at different scale levels, a classification of dynamic rock pressure manifestations in mines has been developed, in which each type is characterized by the released energy and area (volume) of manifestations in mine workings.

The results of upgrading the software for parallel borehole method aimed at improving stress calculation accuracy and equipping software with a present-day interface are presented. To solve boundary value problems, an algorithm of linear combinations is applied. Experimental data obtained using borehole deformation gauge are processed.

It is shown that there is no such a model as intact rock mass, there is only a first one-dimensional approximation, i.e. experimental determination of principal stresses at the point of a future underground excavation. The case of ground surface above rock mass with an underground excavation affecting natural stresses is considered. In transition from open-pit to underground mining, the obtained results are essential when considering only correct problems which are the theoretical background for any calculation.

In order to verify and confirm the specified performance characteristics of arched yielding support made of a special interchangeable profile, the problem of determining its stress-strain state is considered. Most sensitive assemblies and support elements were identified for different operating modes, in which the limiting case - plastic strain development occurs first. It is shown that reliability and operability of an arched metal three-link yielding support depends on the strength of yielding assembly. At the same time, its maximum bearing capacity is provided in a hard operating mode.

The experiment of applying the upgraded Gidrorazryv system when studying stress field parameters in the Tashtagol mine and Yubileynoe deposit (Republic of Kazakhstan) is presented. The alternative layouts of measurement stations and the features of experimental hydraulic fracturing stress measurement are discussed. The experimental estimates of stress components in the vicinity of underground mine workings are presented.

On a site with a unit normal, in addition to the stress vector, the deformation vector is set as a vector of relative displacements of the site points (it is equal to the ratio of the displacement vector to the distance from the offset reference point to the site). The deformation vector has properties similar to the Cauchy stress vector (the principal vector and the principal moment of the deformation vectors referred to the medium element vanish). For an initially isotropic medium, the work of the stress vector on the site is calculated on the basis of changes in the deformation vector. It is shown that it is non-potential, i.e. depends on the nature of the change in the stress vector. Work is potential for an isotropic medium only on areas equally inclined to the principal axes of the stress tensor, i.e. on octahedral sites. This position is valid for the states of elasticity, plasticity, extreme deformation.

A practical solution for selecting the optimal mining system for Serebryakovskaya vein of the Irokindinsky deposit is presented. The geological and engineering conditions for mining the deposit were analyzed and the areas with complex conditions where specification of physical and mechanical rock properties is required were identified. Analytical calculations of main mining parameters were performed using numerical 3D modeling in the software package Map3D.

The use of mining and geological information systems for designing blasting operations in mining solid mineral deposits by the open-pit method is analyzed. The features of digital design in various domestic software products are noted and examples of their implementation at mining enterprises are given. It is shown that in conditions of a constant increase in the complexity of deposits being mined and planned to be mined, it is necessary to improve the digitalization of blasting operations to increase the overall efficiency and safety of open-pit geotechnologies.

Variants of the transition from two- to three-entry preparation of a series of very close shallow coal seams are considered, including methods for determining the minimum width of belt pillars based on the stability criteria of supported developing entries and prevention of geodynamic phenomena. A methodical approach is elaborated for the sequential transition from the production-tested two-entry preparation and mining of the extraction pillar to three-entry preparation.

The results of investigation into the effect of static and dynamic stresses on support when sinking the ring drift in the Safyanovsky underground mine are presented. A measurement technique is developed that allows recording the velocity of rock mass displacement at several points using three-component GS-20DX geophones connected to the recording computer by means of seismic streamers. An assessment of the support type of a ring drift is made for compliance with the effective loads, taking into account the influence of blast seismic effect during sinking the drift.

The results of studying gas purification from nitrogen and sulfur oxides by natural zeolites are presented, the corresponding dependences are obtained. It is shown that the most effective sorbent for gas purification is the iron-containing modified zeolite of the Shivyrtuisky deposit. The sorption capacity of natural zeolites is determined, the modification parameters are found.

The publications concerning the development of the Bakcharsky deposit of oolitic iron ores in the Tomsk region are analyzed. It is noted that under relatively simple mining and geological conditions, the deposit has an increased degree of water encroachment, which is one of the decisive factors when selecting a method for its development. According to the preliminary estimates, the deposit is considered as a large promising raw material base for the West Siberian metallurgical complex. It is shown that any possible mining method can be used for ore production, including open-pit, underground methods and their combinations, borehole hydraulic mining that provide an environmental safety.

The structure of a geological section used for drilling degassing wells in coal deposits is given. The advantages of the impact-rotational drilling method are shown. The procedure of core sampling using down-the-hole pneumatic hammer is presented. Annular pneumatic hammer with a central sludge transport is described. Down-the-hole pneumatic hammer of a solid face with an adapter redistributing the movement of drilling mud from the annular space to the central pipe of a double drilling string is considered.

The relevance of using pneumatic impact machines in conditions of confined technological space is justified. Examples of pipe driving into soil by means of small-sized pneumatic impact machines are presented. Vibratory percussive penetration of vertical pipes with different diameter was physically simulated, the results are presented. The effectiveness of using an experimental model of pneumatic impact machine with two controllable chambers for driving pipes in soil is proved.

A procedure for calculating the parameters of a reverse action hydraulic hammer (with an elastic constraint between the striker and the frame) is proposed, which can be used at the stage of its preliminary design. The method is based on the assumption of a constant pressure in the system and linear nature of the constraint between the striker and the frame. This allows obtaining formulas for calculating the dynamics and characteristics of the system using the equations of oscillation theory. Since the problem is iterative in the case of interaction between the striker and outside environment with a non-zero recovery coefficient, recursion is used in the algorithm for calculating the output characteristics of limit cycles. A program is developed and test calculations are performed. The results are compared with similar results obtained using a software for calculating the parameters of hydraulic impact devices based on a system model with a constant flow source. Satisfactory convergence of these results is noted.

Analysis of the existing methods for calculating the coefficients of proportional-integral controller of axial fan performance system in a shallow subway was carried out. The technique of calculating the controller coefficients in the Mathlab (Simulink) environment is presented.

The design features of vibratory transporting devices with elastic actuators, mainly feeders, developed at the Chinakal Institute of Mining SB RAS are described. In order to increase the distance of transportation and the possibility of using such machines in various technologies for processing minerals, it is proposed to use an additional vibration source in their drive. The dynamics of an elastic actuator was investigated during the operation of two vibration exciters in a synchronous mode and a beat mode by physical modeling. The conditions of stability are found and the scope of application of both modes is determined.

The results of studying the nonuniformity effect of air flow velocity field entering the axial fan on aerodynamic parameters of main mine fans of the shafts for different configurations of input elements are presented. A parameter for estimating air velocity nonuniformity at the fan input is introduced. It is shown that dependence of total pressure and total efficiency of the fan system is linear.

As a result of a computational experiment, the parameters of transient air distribution from the piston effect of trains and the structure of air stream at the places of filter installation are determined depending on their locations in a ventilation connection. The dependences of change in air consumption at the station on the coefficient of closing section of ventilation connection are obtained.

The results of studying aerodynamic processes in a very long (up to 400 m) coal longwall are presented. A method for increasing the efficiency of coal longwall ventilation by installing an axial jet fan on a shearer is considered and the advantages of using this method are evaluated. As a result of computational experiments, the dependence of longwall aerodynamic resistance on the location of mechanized coal face system is found.

The results of investigations into the influence of different blade assembly designs on its stress-strain state and frequency properties in various operating modes are presented. It is found that at fan impeller diameters of more than 3000 mm, a part of blade assembly elements causes a significant stress concentration. Recommendations for designing such blade assemblies are given.