Home – Home – Jornals – Fundamental and applied issues of mining 2019 number 2

The article presents calculation methodology for evaluating both the technical conditions of the VS-3 mine shaft and the state of rock mass at the Oktyabr’sky mine for the purpose of providing for the safety of mining operations while under-mining rich ores. The proposed method serves as a basis for quantitative and qualitative analysis of the rock mass stress-strain state in the developed areas and inferences about appropriate protective measures for mine workings.

The article deals with the issues related to developing the hardware and software for a tool system for conducting full-scale investigations of the stress-strain state in rock mass. The problem solution using the temperature programming technique for drift compensation and exponential smoothing of signals from strain gauges is discussed. The mathware and software modules allow, during the in-situ rock stress measurements, to observe in real time the process of radial displacements of the measuring well contour while drilling and loading the parallel signaling well, as well as to store the original data in files for their office processing and archiving.

Laboratory tests of the physico-mechanical properties of enclosing rocks of the Botuobinskaya pipe are carried out at PJSC ALROSA in three wells 600 m in depth. The strength characteristics of rocks in thawed and frozen states are estimated. The research results of various lithotypes of rocks are presented and the dependences of their strength characteristics on moisture are found.

Physical modeling was carried out to study deformation processes on plexiglass models with cylindrical cavity under quasistatic loading. Thermal and strain fields were measured during the experiments. The thermal field analysis revealed four regions in the model: two of them are located to the left and to the right of the cavity (those receiving the main load), and two are above and below the cavity. The high temperature values recorded on the lateral surfaces of the cavity indicated their significant deformation. When the applied load was taken off, the model temperature decreased sharply (due to reverse deformation) to the extent that it became lower than the ambient temperature, and then gradually increased.

The extensive seismological data bank for one of the deep mines of the Norilsk-Talnakh polymetallic deposit is analyzed in order to assess the rock-burst hazard of rock massifs. The criterion proposed for this assessment is based on the relation of kinematic characteristics of seismic processes used as migration velocity of reduced center of seismic energy release and apparent rate of aftershocks related to the time of their occurrence for selected major seismic events within the controlled zones of mine field stresses concentration. The minimum value of this parameter characterizes the state of controlled area of the rock mass as rock-burst hazardous. The most significant energy-related seismic events occurring in such time periods result in the rock massif “discharging” the accumulated energy. Then the value of the rock-burst hazard parameter increases, and the controlled area passes into non-hazardous state. Verification of the proposed parameter for assessing the rock-burst hazard, performed for the “Skalisty” mine of the Norilsk polymetallic deposit for the period 2015 - 2017, has demonstrated that the ratio of the kinematic characteristics of seismic processes can serve with a high degree of reliability as a criterion for rock-burst hazard of controlled areas of rock massifs.

An experimental version of the multichannel measuring and computing system Karyer including the measuring complexes Karyer-L and Karyer-T is developed and manufactured. In 2017, the complexes were tested in the continuous monitoring mode at the mine of Zarnitsa diamond pipe. The condition of the “edge - berm” section and the section with a crack were monitored. The monitoring results in the period from 09.07.2017 to 25.09.2017 are presented.

The presented computer program for selecting parameters of hydraulic percussion hammers of single-sided direct and reverse action is based on the tabular data of dimensionless characteristics of hydraulic percussion systems in the space of their basic similarity criteria. The program offers a user the options of setting initial parameters and characteristics of hydraulic percussion systems as their values and possible constrains. The program results in determining all the parameters necessary for a preliminary design of the hydraulic percussion system. The Java-based program has a graphical interface, including menus, toolbar, dialog boxes for input parameters and output tabular data representing the main parameters options, as well hammer head sizes and plotted dynamic characteristics of the working cycles.

The technique of measuring the accelerations generated in the elements of the striker head - tool system is presented when it interacts with the rock mass. The measurements oscillograms and their analysis are shown. The quantitative aspects of the phenomenon are discussed, and an attempt is made to reveal the relationship between the quantitative parameters of impact pulses and fracture results.

A physical model of a hydraulic percussion device is presented, in which the frequency is regulated by a standard flow rate controller, and impact energy - by an original distributor with throttle control, which allows delaying the striker before the start of the reverse phase. A series of experiments is conducted with recording of the characteristics of the work cycles required for the analysis of the system dynamics. Recommendations for possible improvements of the hydraulic percussion device performance are given.

This paper provides a comparative analysis of technological characteristics of the methods of puncture and pile pushing and their combination in horizontal hole-making in soil mass. The results of experimental studies of the interaction between the working tools and soil massive for these methods are given. The combined method potential for expanding the technological capabilities of boreholes construction is substantiated.

The results of pilot tests to reduce the quantitative dilution indicators in room-and-pillar mining systems with backfilling of the mined-out space used in the PD PJSC MMC Norilsk Nickel are presented. The reasonable parameters for drilling-and-blasting operations are determined.

To assess the stability of mine workings, the mechanism of deformation, displacement and collapse of rocks in a structurally disturbed heterogeneous massif is investigated. Technological conditions are developed for stabilizing the soil of working, taking into account the state of the rock mass. The parameters of roof bolting ensuring the safety and efficiency of mine operations are obtained.

The problem of engineering and geological support for drilling-and- blasting operations in a frozen rock mass with underground ice reducing the blasting efficiency is considered. A survey of methods for underground ice searching is carried out and the georadiolocation method is proposed as one of the most operational and efficient. Underground ice identification criteria are developed which allow using the georadiolocation method for searching the formation ice, simplify and accelerate the georadiolocation data processing .

The basic research aimed to substantiate implementation of ideas and principles of converging engineering and biological sciences in the sphere of mineral mining is accomplished. A methodological concept is proposed to create a convergent technology for underground mining of thick ore deposits. The design features of a new frame-type technology are discussed and the efficient procedure of extracting ore panels is justified. Numerical modeling of stresses and elastic strains at the boundaries of stoping blocks is carried out at various criteria of rock mass disturbance.

The conditions that must be taken into account when developing equipment for interval fracturing of a coal seam are investigated. The expediency of providing the packer with a profiled blade for passing clogged well sections is determined. The use of experimental equipment increased the methane yield from the well by a factor of 2.5.

A method for determining the strength characteristics of rocks under tensile conditions has been tested. It is based on testing samples with axial holes of different diameters loaded diametrically. The test results of rock samples and simulating media in the form of hollow cores broken diametrically are presented. The test results were processed using gradient and integral strength criteria. The values of fracture resistance and tensile strength obtained on the basis of this approach are compared with those measured in a standard way.

Results of the mechanical and mathematical modeling of the movement of a hoist vessel (skip) in underground mines are presented. The numerical solution algorithm of the obtained model is developed using the data derived from the existing system for skip hoist movement smoothness monitoring. The algorithm allows to calculate the impact of skip on the guides, specifically, the horizontal components of the force acting on the guides in the place of their contact with the hoist skip. The guides were evaluated for horizontal deformations as well for potential occurrence of plastic deformations and the momentum of the existing forces acting in the plane perpendicular to vertical axis of the hoist system.

This paper presents results of the mathematical modeling of deformation processes in a multilayered rock massif, which take place in the neighborhood of a vertical excavation (shaft) before it is provided with concrete-lining. An algorithm for solving geomechanical modeling problems of such type is proposed. The areas of discontinuity and destruction of the rock surrounding the shaft are evaluated according to different limit criteria. The modeling was performed using the computational schemes based on the finite element method. It is shown that the rock mass should be checked for the presence of hazardous zones justified by more than one criterion, because discontinuity of rock mass can be caused by a wide range of factors.

The main quality parameters of automatic control and its application to ventilation system control in shallow-depth subways are analyzed. The choice of a number of quality factors for automatic control of subway tunnel ventilation system by variation of rotor speed and opening angle of the valve of air distribution controller is justified.

The flow chart of the hydrodynamic effect on coal rock mass is developed and presented, including the packer introduction into the well, well sealing, hydraulic fracturing, unsealing and displacement of the packer. The process of fracture formation and development during injection of fluids into rocks is investigated. It is shown that a coal seam loosens under the influence of a series of repetitive pulses of change in the pressure of fluid in the borehole space. The estimation results of the coal seam state before and after stimulating its gas recovery by the seismological method are discussed.

Based on the Discrete Element Method a 3D numerical simulation of the process of discharge flow of coal mass during the underground mining of thick seams using a self-caving technology has been performed. Discrete elements are clusters composed of three spherical particles with a preset radius distribution. When calculating the tangential forces acting between the discrete elements, dry friction and rolling resistance are taken into account. The kinematic pictures of the rock mass flow depending on the number and location of the outlets are given, with determined zones of their mutual influence.

It is shown that mineral mining and processing operations produce inflow of highly toxic arsenic compounds in considerable amounts to water bodies. Among the promising methods for arsenic removal from aqueous media are the sorption technologies using available natural adsorbents and oxidizers. Results obtained from the experimental removal of arsenic compounds by adsorption on magnesium- and manganese-bearing minerals are studied. It is found that the use of this natural mineral material can essentially enhance efficiency of the environmental strategies in mining and mineral processing industries.

The paper presents results of the experimental study of hydraulic fractures formed by viscous liquid, which is initially generated from an initiating disk crack under compression stress conditions. Experimental dependences of crack geometries on injection velocity and viscosity of working fluid are obtained. The influence of working fluid properties on parameters of the developing cracks is analyzed.

The relevance and advantages of borehole drilling technology with simultaneous casing applied to drilling CBM (coal-bed methane) wells from surface in advance of mining are discussed. The description and principle of operation of the equipment used for the casing collar installation in soil mass are given. The practice of batchwise removal of soil plug from the well is described. The results of the study of well drilling in stratified rock masses with bottomhole cleaning are presented.

The requirements for achieving numerical geomechanical estimates close to real conditions are substantiated. Limitations in modeling which predetermine the reliability and accuracy of prediction of the rock mass mechanical behavior and mining structures are identified. It is shown that creation of a geomechanical model for an existing or newly developed mine allows to solve the problems of the operational choice of the method of rock mass state control at the opening, preparation and stoping stages at a qualitatively new level. This will also help to develop a set of scientifically justified recommendations and engineering activities for safe deposit mining at different phases of mining operations with acceptable risks for the enterprise. When performing numerical modeling, special attention should be paid to rock mass fracturing

The impermeability of a cement stone was experimentally studied under the effect of downhole vibration source. It is found that cement stone having a fractured-porous structure in the initial state retains it under static force action. When vibropulse effects occur in the local area of power contact during the first 10 hours of operation, the initial structure of microfractures is converted to a dynamic structure, and the proof-test pressure drop increases by 2-3 times. It is shown that the breakthrough of the liquid phase through the cement stone body does not occur at the standard pressure gradient, which ensures the absence of behind-the-casing flows of fluid and water due to the downhole vibration effect.

Velocity field of air flow in the approach channel of main ventilation plant with fans of VOD series (aerodynamic scheme OV-84 TSAGI) and in the inlet unit was analyzed. It is shown, that there exists appreciable irregularity of flow in the inlet of fan, which decreases along the channel. Based on the analysis of velocity field of air flow, the method for the fan modernization, which consists in replacement of two-stage rotor by a high-pressure one-stage rotor made according to the scheme “inlet guide vanes - impeller - outlet directing vanes”, was justified. This allows to reach the performance objectives and increase the rotor bearing resource by considerably decreasing the weight of rotor.

The article presents results of modeling the dynamics of an extended working tool of low flexural rigidity, driven by two inertial vibration exciters. The influence of the design parameters of the transport device on the mismatch of partial frequencies still sustaining synchronicity of the vibration exciters, and on the angle of phase displacement is established.

Results of the study of allowable dynamic load at the location of category II buried high-pressure gas pipeline within the bounds of the mining property, in connection with blasting operations at the quarry of “Sukholozhsktsement” Company are presented. A calculation technique for estimating distances from the technological blast in opencast mine to the gas pipeline facility depending on the mass of explosives at delay stages, on the soil condition coefficient and ground velocity of vibration rate is proposed. We found that it is possible to completely eliminate the negative impact from explosion on the gas pipeline facility by changing mass of explosive in delay stages. A calculation scheme is also proposed to determine safe distances to the high-pressure gas pipeline based on the bench face angle and depth of blasting works in open pit mine.

Design features and operating principles of ball cavity generators in the rock mass through boreholes are considered. A technical solution to the formation of ball cavities is proposed and the advantage of its use for estimating the stress state of the rock mass by hydraulic fracturing method is shown in comparison with other methods

The results of numerical simulation of heat exchange between a train and tunnel air in the cold season are presented for the tunnels operated in severely continental climate of Siberia and the Far East. The simulation was carried out in an unsteady plane axisymmetric formulation. The dependences for the heat balance components of transport tunnels on the outdoor temperature and portal equipment operating modes are obtained.

The possibility of using combined safety shelters to prevent the distribution of rock fragments during blasting in constrained conditions near urban terrain is shown. New schemes and designs of shelters made of dump truck tires connected by rope and chain slings were developed, as well as fencing mesh and mats made of conveyor belts, which ensure blasting safety preventing the rock pieces from flying apart and partially reduce the effect of an air shock wave.

The influence of excavation design features on the stress-strain state and stability of the rock mass and backfilling within the boundaries of block 12c at level 11 of the Orlovsky mine horizon is considered. The main factors of backfilling caving to the mined-out space of stopes are determined.

Based on the geological and structural features of the ore field of the Glubokaya mine of the Skalisty colliery, a parametric 3D model has been developed for numerically assessing the stress-strain state of a tectonically active rock mass. Forecast maps of the stress state of the block geoenvironment at different sequences and stages of mining deeply occurring ore bodies C-5, C-6, C-6 (l) of the Oktyabrsky deposit are obtained. The sequence and safest direction of the extraction front in mining ore deposits are determined.

The study results of changes in the value of local aerodynamic resistances during the air flow reversing are presented. Based on the finite volume method, the aerodynamic drag factors of typical elements of shaft and mine ventilation network are calculated. A comparative assessment of the obtained values with analytical calculations is given. The mutual influence of local aerodynamic resistances closely located in the ventilation network under normal and reversing ventilation conditions is determined.

A method of reducing the power consumption of the main mine fan through the use of partial airflow recirculation is considered. The results of numerical experiments on the calculation of air distribution are analyzed on the mathematical model of mine horizon ventilation network. The dependences of the power consumed for its ventilation on the length of horizon and the distance between the face and circulation connection are determined.

The method for estimating deformation characteristics of carrying elements of the room-and-pillar system of solid mineral underground mining and horizontal components of the natural stress field is considered The method is based on solving inverse problems of mixed type within the framework of two-dimensional elastic medium model. The required amount of measurement data, ensuring the unique solution of the inverse problem is obtained by numerical calculations performed for a typical configuration of the goaf, using synthetic input data (relative displacements of the goaf contour points, registered by underground geodesy methods).

The resource potential of zeolite-bearing rocks in Eastern Transbaikalia is evaluated. The prospects of complex development of zeolite-bearing rocks and their processing in the Transbaikal territory are studied. The climate-related factors affecting stability of natural complexes under anthropogenic impact are determined. The main directions for reducing the negative impact of zeolite production on the environment are defined.

The experimentally tested borehole equipment for measuring elastic properties of hard rocks, which also provides for controlled uniaxial loading of open hole walls perpendicular to its axis, and for strain measurements in a wide range of loads with automatic data recording is considered.

A method for calculating the stress-strain state of the lining of mined-out area at any mechanical parameters, allowing to take into account any displacements of the contour of excavated rock surface before it contacts with the lining is proposed. The method is based on the use of the intact rock mass stiffness matrix formed prior to mining. Modeling of the cavity growth and joint deformation of the lining and rock mass surrounding the excavation opening is performed using iterative procedures of the methods of initial stresses and initial strains. An appropriate algorithm and software complex for calculating loads on the lining of mined-out area have been developed.