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The stress-strain behavior patterns in rockburst-hazardous rock mass are described as a case-study of mineral deposits in Gornaya Shoria. The microseismic research data on development of rockburst hazard criteria are described. Geodynamic events are predicted in extraction blocks during basting, with detection of possible damages in underground openings using the obtained patterns of different energy shocks.

Based on the mathematical modeling of the geomechanical condition of a coal face, it is shown that destruction of the face zone occurs in the form of squeezing-out and spalling within an operational cycle. The acoustic noise in the longwall is analyzed, and the noise spectrum peak frequency is determined. The peak frequency is reflective of the size of the damage area in the face zone.

The paper concerns an interpretation of high-precision gravimeter observations in the Upper Kama Potash Salt Deposit. The studies aim to detect the mining-induced softened areas in undermined rock mass. It is found that the gravity field transformants exhibit induced softening areas as flat inclined negative anomalies that intersect the undermined rock mass from top downward. The spatial location of the induced softening areas in rock mass is determined.

For this study, as part of the underground operations, the underground mining sequence was explored for suitability in the Zuuntsagaan mine. Two mining sequences are considered; bottom-up (B-U) and top-bottom (T-B), and the instability of stopes and open pit slopes is evaluated in response to each sequence. For the present rock mass conditions and stress state, with reference to the underground section, the results revealed that T-B sequence has lower ground movements. On the open pit section, the effect of the two sequences is relatively the same while the difference is mainly observed in the underground section.

In this study, a path search algorithm is introduced for exploring the ultimate pit limit using the Lerchs-Grossmann method. In an iteration of the algorithm, each vertex of the solution is randomly moved within a specified neighborhood. The vertices’ motion in such a neighborhood ensures that the formation of abnormal shapes is prevented. Since an open-pit design needs to address geomechanical concerns coincident with economic value maximization, the movements resulting in segments steeper than an allowable slope angle are discarded. For each valid vertex movement, the benefit of the resulted pit limit was calculated. The new position of the vertex is accepted according to a probabilistic regime in order to prevent the algorithm be trapped in a local maximum. Independence of the slope from the block size is one of the main advantages of the suggested algorithm. Hence, the algorithm provides a better mapping to the ore body and results in a higher benefit. The reason is the mobility of the path search algorithm and its high flexibility.

The authors discuss the approved advanced control charts for operational cycles of hydraulic impacting machines. These control charts allow adjusting operational characteristics of the machines either using only pressure back-coupling between the fluid power system and distributor, or in combination with introduced additional pressure control. The article describes adaptive impacting machines equipped with the control charts which allow adjustment of blow energy and frequency subject to properties of a medium being fractured. It is emphasized that to expand the application range of hydraulic impactors, it is required to design high-frequency percussion machines with high impact capacity owing to improvement of distributors and due to transition to the increased power fluid pressure.

The author analyzes spectra of a downhole impulsive vibration source with two power-supply units and an electromagnetic hammer using the Fourier series. The amplitude-frequency characteristics of the impulsive and unbalance-mass vibration sources of adequate sizes are compared. The impulsive vibrator has much higher amplitudes and spectra of output signals than the unbalance-mass vibration source.

The study addresses efficiency of natural cold and the permafrost properties in the Central and Arctic Yakutia in holding of frozen cola in buried storage rooms. The heat transfer modeling takes into account the climate, parameters of a storage room and heat insulation. It is shown that coal thaws less than the host rocks because of its low thermal conductivity. When a storage room is filled in winter, coal will remain frozen for a few years, and heat insulation will greatly reduce the rate of thawing in the overburden. It is emphasized that as against the width and slope of the storage room, its occurrence depth is the main factor to govern the size of the thawed zone by the end of the warm period of storage. Natural cold in the buried storage room decreases coal oxidation, preserves coal properties, and improves energy security of the hard-to-reach areas.

Exploitation of Mutnovskoe Geothermal Field, which is a key asset of geothermal power engineering in Russia, is faced with the problem connected with reduction in pressure in the producing reservoir, which results in decommissioning of production wells. Production capacity of planned wells 3 and 4 km deep for treating deeper horizons in Mutnovskoe Field is predicted. The prediction results are compared with the data of a standard production well 2 km deep in this field and prove the promising nature of the deeper horizons of this reservoir. In particular, essentially greater steam flow rate out is expected in the deeper production well as compared with the standard well. Furthermore, it is expected to produce much more geothermal energy owing to the increased allowable reduction in the reservoir pressure and thanks to additional heat elimination from larger volume of enclosing rock mass of the produced fluid.

Based on the mathematical model of hydro vortex orthokinetic inertia hetero coagulation, the hydro-vortex nozzle parameters air identified for a dust suppression facility for prevention of blasts and induced accidents in mines. Using the similarity theory and dimensionality analysis, the similarity criteria are obtained for the process of dispergating in the conditions of rotational motion of liquid drops. It is shown that the main pulverization efficiency criteria for liquid drop in the hydro vortex nozzle are the Weber number, Laplace criterion and three indicators of inertia and viscosity of liquid, and kinematic similarity. The calculations and tests reveal the possibility of enhancing dispergating efficiency by 15%, reducing the average diameter of liquid drops by 2.5 times, and reducing the liquid flow rate by 10%.