Mineral demand rapidly increases; as a result, underground mining activities gradually dig into the earth’s crust to deeper levels. For instance, the depth of coal mines has reached 1500 m, whereas the depth of mines for nonferrous metals has already achieved around 4500 m. Deep mining faces a number of technical and environmental challenges, first of all, great rock mass stresses, high temperature and long winding distance. The traditional technologies are hardly capable to provide the development and extraction efficiency and safety. That is why the need in developing and implementation of new modern mining technologies arose. In roadheading, TBM (tunnelboring machine) method is gradually introduced. A TBM combines the functions of rock breaking, support installation, mucking and conveying rock. In mining industry, smart mining based on mechanized and automated mining methods is successfully implemented at coal mines. Besides, a technical concept of fluidized mining for deepseated mineral resources (6000 m and more) was proposed. This paper presents the review of the current global status of deep mining and highlights some of the newest technological achievements in roadheading and the mineral extraction processes.

The relevance of research of material strain nature based on physical models equivalent to rocks is substantiated. To identify the dependencies and mechanism of unstable rock strain in the vicinity of mine working junctions, an experimental technique has been developed and presented. The method of physical modeling using equivalent materials was applied in the research. Strength characteristics of the rock equivalent material were calculated using the formulas proposed by G.N. Kuznetsov. The equivalent material was prepared based on two components, sand and paraffin. The mix formulation was selected, and ultimate compressive strength of the equivalent material was determined. The experiment was performed for three options of the physical models: an intact rock mass, a rock mass with a single mine working, and a rock mass with mine working junctions. Testing of the models made of the equivalent material was performed through uniaxial vertical loading using a hydraulic press. Based on the model testing findings, the dynamics of fracture propagation and crushing of the enclosing equivalent material in the vicinity of an artificial cavity, simulating a mine working, has been demonstrated. Besides, the graphs of relative strain versus vertical loading for each stage of the stepwise loading of these three model options were produced. The findings of the strain-stress distribution modeling for the equivalent material around the cavities simulating mine working junctions were analyzed. The strain testing findings for the materials simulating rock behavior are expected to be used as the initial data for analysis of physical and numerical simulation, as well as for developing engineering documentation with regard to the selection of parameters for supporting mine working junctions.

The study of atypical manifestations of rock inelasticity improves understanding of the physical mechanisms of seismic wave propagation and attenuation in real environments. In the field experiments, the propagation of longitudinal wave at frequency of 240–1000 Hz between two shallow boreholes in low speed zone was investigated. The measurements were performed using a piezoelectric pulse emitter and similar receiver tools positioned in the boreholes. "Stress-time" σ(t) digital responses were recorded by the open channel with microsecond temporal resolution. The unusual short-period variations of amplitude in the form of sharp flattening wave front, stress drop, or plateau of different width (tens of microseconds) were detected in the wave profile. These low-amplitude variations in the waveform were regarded as manifestations of hopping intermittent inelasticity. This inelastic process was assumed to affect the waveform transformation. The contribution of hopping inelasticity depends on the applied stress magnitude, i.e. in this case, the seismic response amplitude. The mechanism of hopping inelasticity at small strains may be explained by microplasticity of rocks. The findings obtained represent a new step in understanding of physics of seismic and acoustic wave propagation in rocks and can be useful for handling of applied problems in geophysics and mining.

The main factors affecting the nature of uneven hydrocarbon saturation of the AC10 formation reservoir at Priobskoye field located in Western Siberia are considered. The formation is characterized by extreme heterogeneity caused by macro- and microstructure, which is determined by the lithofacial and structural-morphological conditions of sedimentation. The formation is characterized by high variability of lithological-mineralogical composition and textural and structural features. To bring to light the nature of the uneven hydrocarbon saturation of the reservoir, the combined analysis of the findings obtained from the study of the size of capillary channels and pores, as well as the investigation of the degree of their filling with clay and carbonate material, was performed. The analysis has shown that the filler composition, its amount in the pore space, and the (core) hydrocarbon saturation collectively evened the AC10 formation electrical resistance in different saturation zones, which led to distortion of the hydrocarbon saturation of the reservoir as a whole.

The research is aimed at solving problems of assessing underground working stability in complicated mining and geological conditions to increase reliability and safety of mining operations. Analysis of geomechanical processes occurring in a rock mass during extraction of coal seams to determine the stability of mining block roof is the most important task. The performed digital modeling of the rock mass based on the structural logs for K1 seam and the nearest borehole log enabled highly detailed identifying the types of rocks occurred in the seam roof and their strength characteristics, compressive stresses. To determine the stability of a mining block roof, the factor of safety of the rocks was used, which was determined by modeling method using Phase 28.0 and Rockscince software. The carbonaceous argillite parting 0.09–0.12 m thick was taken as the contact of the longwall with the seam roof, and, for completeness of the analysis, the upper high-ash coal member in the seam roof up to 0.7 m thick was used. The modeling findings, presented in the graph of dependence between the safety factor and the distance between the belt heading and air drift, showed that the probability of dome formation in the longwall is high, as the factor of safety of the rocks is less than unity, that indicates the roof instability in the course of the coal seam block extraction. The modeling methods allowed assessing the mine working stability, based on which the measures to improve the reliability and safety of mining operations can be timely developed, and due technical and technological solutions shall be reached.

Landsat multispectral images have been successfully used for discovering some mineral deposits in different regions of the world. Some minerals, including clay minerals and iron oxide, can be detected by multispectral surveys due to their spectral characteristics. This paper presents the results of the application of principal component analysis and Crosta technique for detecting accumulations of clay minerals and iron oxide based on a Landsat 8 Oli multispectral image of Thai Nguyen Province, north of Vietnam. The obtained results have demonstrated the feasibility and suitability of prompt detecting mineral deposits based on the remote sensing data. The image processing methods and facilities tested in this study can be used to create maps of distribution of clay minerals and iron oxide for effective and expedient prospecting and exploration for minerals.