Home – Home – Jornals – Advanced Search

The articles describes the studies of influence exerted by operation of a jet fan installed on a shearer on air drag and on methane and coal dust concentrations in a longwall. The investigation used ANSYS Fluent and field data from coal mines in Kuzbass. The object of study was dust and gas/air mixtures in extra-long panels with a length of 400 m and at mineable coal seam thickness of 2.4 and 3.7 m. It is found that jet fans can decrease air drag in such longwalls by 35%, which enables decreasing the air feed in the longwall by 24% without increasing the main fan capacity. The air flow generated by a jet fan eliminates dead methane-air zones nearby an operating shearer and decreases coal dust concentration at work places of shearer’s operators by 13.8-36.7%.

The authors address a relevant problem connected with digital transformation of the mining industry toward import substitution and creation of a barrierless technology to operate digital data and models of objects of a mining technology with a view to solving tasks in geology, surveying and engineering. An important component of a barrierless technology is a single virtual digital space for the database translation when using program products based on different object models. Such technology is implementable through formation of a digital platform containing a basic function to operate object models in digital space and API-functions to integrate the created tools into this digital space. The requirements of the digital platform are to the largest degree met by the program products of mining and geological information systems. In the digital space of such systems, 3D modeling is performed and basic mining and geological problems are solved. The article formulates the main functionality standards of such digital platform and describes the current situation in creation of the platform using the mining and geological information system (MGIS) MINEFRAME at the Mining Institute, KSC RAS, and at MINEFRAME Laboratory LLC.

The article presents an analysis procedure for remote sensing imagery for monitoring ground surface objects. The studies on development of an algorithm for identifying mining waste disposal facilities on ground surface are described. The source data were Sentinel-2 and Landsat 5-8 images of the southern area in the Russian Far East. Using Earth Engine platform, the vegetation index is calculated for each pixel using the function of normal distance, and the test area is generated using a standard tool. Pixels were converted to square units using the reduce() method. The proposed procedure is of current interest in monitoring various objects (tailings ponds, surface mines, waste dumps, etc.) at different stages of development.

It is found that zeolite-bearing rocks from the Khola deposit can be dressed toward manufacture of high-quality sorbents to remove impurities from waste and recirculated water, and the relevant processing circuit is proposed. The mineral composition of the Khola zeolite-bearing rocks is described, and their electromagnetic and electrostatic separation results are reported. The layout of a continuous adsorption plant using zeolite-bearing rocks is developed. The sorption capacity of original and dressed zeolite-bearing rocks from the Khola deposit is tested in model solutions. The test data of arsenic adsorption using zeolite-bearing rocks are presented. The efficiency of zeolite-bearing rocks in removal of arsenic, fluorine, zinc, lead, nickel and chrome from a model solution of waste water is evaluated and compared. The prospects of using zeolite-bearing rocks in mine waste water treatment and in removal of impurities is assessed. The resultant purification boasts high-value results which ensure the required quality of waste water.

This article describes a method to detect and control low-velocity intercalations in rock mass in neighborhood of tunnels and underground mine workings using calculated phase velocities of surface seismic waves. Initial data are synthetic seismograms from numerical modeling of radially symmetric propagation of seismic waves along a mine working. It is shown that overlapping of a low-velocity heterogeneity in rock mass by a higher velocity layer brings no obstacles to the identification of the heterogeneity by the proposed method. Observations over phase velocities of surface seismic waves make it possible to assess rock mass adjacent to underground structures, which is a relevant result from the practical point of view.

The limitations of traditional methods of rock mass classification are reviewed. A modification is proposed for the Hoek-Brown failure criterion, with the compression strength of rocks presented in an explicit form. An approach to the compression strength assessment is taken on the ground of generalized results obtained by Kim in experiments with model block structures made of equivalent materials. An approach to determination of scale effects on strength, deformation modulus, creep and internal friction angle is described. The constant of creep is introduced, and the correlation dependences are obtained to find the creep constant in four types of rocks. It is found that the ratio of displacement at the boundary of a mine opening to displacements in the plastic strain zone can be approximated by a function of the internal friction angle only. This concept is used to calculate internal friction angles in rocks from the analysis of field measurements. The author puts forward two hypotheses and makes an attempt to substantiate them. Hypothesis A supposes that a scale effect in similar structure rock mass depends on the compression strength, and weaker scale effects are typical of hard and brittle rocks as against softer and plastic rocks. Hypothesis B supposes that time of stress and strain relaxation increases in a larger rock mass volume while the strain rate decreases.

The author calculates initial stress state generated under the action of gravity and temperature which changes linearly with depth in stratified rock mass. It is shown that the dominant influence is exerted on the initial stress distribution by the parameter δ which is a ratio of products of triaxial compression moduli and linear expansion factors of rock layers. In two-layer rock mass, when δ calculated as a ratio of thermomechanical characteristics of the upper and lower layers is higher than one, the temperature effect results that the tensile vertical stresses are induced in the lower layer; when suchwise calculated δ is lower than one, the compressive vertical stresses arise in the lower layer. In case of a great divergence of δ from one, in the lower layer, the initial vertical and horizontal stresses increase jump-wise, and the stress pattern resembles a hydrostatic stress distribution. The author performed mathematical modeling of thermal stress field redistribution during advancing undercut-and-fill operations. The software used in the calculations took into account the backfill sequence. The features of stresses in enclosing rock mass and in backfill were revealed.

The article describes the calculated temporal development of the stress-strain behavior for the tubing support-concrete lining-rock mass using a finished 3D numerical model. The model passed verification with the help of laser scanning data on tubing support in two shafts. The factors of safety are obtained in terms of compressive stresses and strains. The authors make recommendations on using tubing of certain sizes in shafts 7 and 8 m in diameter at different depths.

The framework of the research are Bridgmen’s and Farbman’s models for viscosity of powders. The article reports the uniaxial compression test data for ground materials. The authors give examples of calculation of viscosity for coal, quartz, sandstone and sandy shale.

The shear creep failure mechanism of jointed soft rocks is a critical issue in geotechnical engineering. Using the discrete element method, a numerical model of jointed soft rocks was constructed to simulate shear creep under varying joint roughness, normal stress and shear directions. The effects of multiple factors on the creep deformation of soft rocks were then analyzed. Results indicate that the amount of creep deformation in soft rocks significantly decreases with an increase in joint roughness and with an increase in normal stress. However, the influence of shear direction on creep deformation is relatively minor. This study lays a foundation for further research into the creep behavior of soft rocks.