Rational use and protection of subsurface resources in the underground mining of ore deposits in conditions of technogenesis

The basic scientific and practical results of rational use and protection of subsoil under underground mining of ore deposits in the conditions of technogenesis are based on reliable geological and surveying and geomechanical support, taking into account the stability of rock masses and the dimensions of the contour energy zone. It is recommended to build ore contours based on the data of advanced exploration (drilling of explorers through 25 m, test wells – after 5-6 m and explosive wells – through 1,2-1,5 m)

Enhancement of confined blasting of ore

Underground mining of ore deposits features worsening of geological and geotechnical conditions, exclusive standards of environmental protection and subsoil conservation as well as more stringent requirements of life safety in the influence zones of mining. This study focuses on higher efficiency of confined blasting through justification of blast design with regard to a required grain-size composition of broken ore (average linear size of ore particle after confined blasting) and safety of guarded objects in terms of industrial and residential infrastructure in the influence zone of mining (the Ingul River underflow, domestic buildings and social framework objects in the settlement of Kizelgur in the suburb of the Kropyvnytskyi city, Ukraine, etc.). The study used analytical, mathematical, in-mine, laboratory and experimental research methods, mathematical and physical modeling, as well as the analysis and assessment of the confined blasting technologies, implementation analysis of pilot confined blasting at the preset grain-size composition, and the analysis of geological and geomechanical conditions on Level 280–210 m in the Michurin deposit (Ukraine) by standard and new procedures (developed with participation of the present article authors). The novelty of this study is justification of the ratio of fragmentation by confined blasting as 1.2–1.3. The fragmentation ratio is one of the main parameters in calculation of length of a section composed of layers (rows). After confined blasting in such section, fragmentation is limiting and equals on average 3.0 kg/m3 at rock hardness of 12–18 and more on Protodyakonov’s scale. As a result of the implemented research, a seismically safe confined blasting technology was developed to be applied in extraction of ore bodies 1, 4, 5 and 10, as well as residual reserves on level 280–210 m of the Michurin deposit. The ecological and social efficiency of the engineering solutions is evaluated

Theoretical modeling of propagation of magneto-acoustic waves in magnetic regions below sunspots

We use 2D numerical simulations and eikonal approximation, to study properties of MHD waves traveling below the solar surface through the magnetic structure of sunspots. We consider a series of magnetostatic models of sunspots of different magnetic field strengths, from 10 Mm below the photosphere to the low chromosphere. The purpose of these studies is to quantify the effect of the magnetic field on local helioseismology measurements by modeling waves excited by sub-photospheric sources. Time-distance propagation diagrams and wave travel times are calculated for models of various field strength and compared to the non-magnetic case. The results clearly indicate that the observed time-distance helioseismology signals in sunspot regions correspond to fast MHD waves. The slow MHD waves form a distinctly different pattern in the time-distance diagram, which has not been detected in observations. The numerical results are in good agreement with the solution in the short-wavelength (eikonal) approximation, providing its validation. The frequency dependence of the travel times is in a good qualitative agreement with observations.Comment: accepted by Ap

Influence of phase-diversity image reconstruction techniques on circular polarization asymmetries

Full Stokes filter-polarimeters are key instruments for investigating the rapid evolution of magnetic structures on the solar surface. To this end, the image quality is routinely improved using a-posteriori image reconstruction methods. We analyze the robustness of circular polarization asymmetries to phase-diversity image reconstruction techniques. We use snapshots of magneto-hydrodynamical simulations carried out with different initial conditions to synthesize spectra of the magnetically sensitive Fe I line at 5250.2 A. We degrade the synthetic profiles spatially and spectrally to simulate observations with the IMaX full Stokes filter-polarimeter. We also simulate the focused/defocused pairs of images used by the phase-diversity algorithm for reconstruction and the polarimetric modulation scheme. We assume that standard optimization methods are able to infer the projection of the wavefront on the Zernike polynomials with 10% precision. We also consider the less favorable case of 25% precision. We obtain reconstructed monochromatic modulated images that are later demodulated and compared with the original maps. Although asymmetries are often difficult to define in the quiet Sun due to the complexity of the Stokes V profiles, we show how asymmetries are degraded with spatial and spectral smearing. The results indicate that, although image reconstruction techniques reduce the spatial smearing, they can modify the asymmetries of the profiles, mainly caused by the appearance of spatially-correlated noise.Comment: 10 pages, accepted for publication in A&

Multifractal analysis of stress time series during ultrathin lubricant film melting

Melting of an ultrathin lubricant film confined between two atomically flat surfaces is we studied using the rheological model for viscoelastic matter approximation. Phase diagram with domains, corresponding to sliding, dry, and two types of $stick-slip$ friction regimes has been built taking into account additive noises of stress, strain, and temperature of the lubricant. The stress time series have been obtained for all regimes of friction using the Stratonovich interpretation. It has been shown that self-similar regime of lubricant melting is observed when intensity of temperature noise is much larger than intensities of strain and stress noises. This regime is defined by homogenous distribution, at which characteristic stress scale is absent. We study stress time series obtained for all friction regimes using multifractal detrended fluctuation analysis. It has been shown that multifractality of these series is caused by different correlations that are present in the system and also by a power-law distribution. Since the power-law distribution is related to small stresses, this case corresponds to self-similar solid-like lubricant.Comment: 22 pages, 10 figures, 41 reference

Increase of ores mining safety based on combined backfilling of mining chambers space

Main research and practical results presented devoted to increase of ores mining safety, based on combined backfilling of mining space. An actuality of the solid stowing usage for backfilling of stoped excavation space shown, when combined with loose stowing during underground mining of deposits. A methodology of research and peculiarities of mining blocks chambers isolation presented when using loose mixture in the combined stowing

Hysteresis phenomena during melting of an ultrathin lubricant film

The influence of a deformational defect of the shear modulus on the melting of an ultrathin lubricant film was investigated in the framework of the Lorenz model used for describing a viscoelastic medium. It was established that the film can undergo both stepwise and continuous melting. Analysis of the lubricant behavior revealed that there are three modes corresponding to a zero shear stress, a Hookean portion in the loading diagram, and a plastic-flow portion. The hysteresis in the dependences of the stationary shear stress on the strain and the friction surface temperature is examined. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/1621