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The sequence of appearance of various atmospheric discharges (lightning, elve, and blue jet) shown on video from the International Space Station is analyzed. For comparison, experimental data on the formation of diffuse, corona, and apokampic discharges with participation of cylindrical and spherical streamers are used. It is assumed that the formation of the elve filmed from the space is initiated by extensive discharges in clouds with subsequent formation of lightning closed to the Earth in this area. In this case, the lightning reaches the positively charged upper cloud layer. The dense plasma of the upper part of the lightning initiates the development of a blue jet, consisting of cylindrical streamers of the ionization wave.

The problem of hydraulic fracture development near a circular cavity is considered in a three-dimensional homogeneous elastic medium. The results of numerical calculations using the extended finite element method (XFEM) implemented in the ABAQUS software package are presented. Different variants of the position of an initial disk fracture relative to the cavity are considered. Some patterns of a 3D hydraulic fracture development near the cavity are found.

According to the borehole logging analysis and near-field transient electromagnetic sounding method, a positive electric resistivity anomaly was detected from top to bottom along the section above the abandoned coal seam. This anomaly indicates a downward movement of groundwater and saturation of rocks with gas.

To study the stress state of “soil body with an inclined earth surface - a system of parallel tunnels” objects, an analytical calculation method is used, which is developed on the basis of obtained new solution to corresponding elasticity theory problem. This method is implemented as a computer program that allows numerical modeling in practical design. Examples of calculation are given.

This article proposes a method based on the disruption theory of an arbitrary discontinuity (the Riemann problem) to determine the shock wave parameters on the wall of an explosion cavity. Two possible variants of detonation wave refraction on the explosion cavity wall are described. The detonative decomposition of emulsion explosives is also considered, and an equation of state for gaseous explosion products is proposed, which enables the estimation of detonation parameters while accounting for the incompressible volume of molecules.

The approaches to the creation of databases that accumulate various information about the deposits of solid minerals are considered. The structure of the database of rocks of the Elginskoe coal deposit and the procedure for filling with information of its constituent sections are proposed. It is shown that the database use provides the highest level of information and analytical support of the geotechnological problems focused on the safe mining and completeness of reserves extraction from the subsoil. A number of coalfield models have been built using specialized software based on the database. The stability analysis of overburden massif of the coalfield has been carried out and geomechanical conditions of open-pit sides have been evaluated.

The problem of constructing a continuous model of hierarchical block geomedium is considered. The basic structural element providing the geomedium structuring is determined, and transition from a hierarchical block to a hierarchical structured medium is discussed. The introduction of four structural levels is sufficient for modeling the geomedium within the Earth’s crust. To describe the fractured structures, a non-Euclidean model of the continuous medium is applied, which considers the violation of deformation compatibility conditions. An algorithm for the transition to a continual description of such structures is presented and nonsingular solutions for a plane-stressed field are constructed. The performed analysis showed that this approach requires hierarchical non-Euclidicity and monolithic block principles.

The authors discuss the structure and formation character of technogenically changed subsoil. A quantitative assessment of the stability of technogenically changed rock mass is proposed, obtained as the sum of the indicators determined using various geophysical and geomechanical methods and characterizing the array of indicators converted into dimensionless quantities by the ratio of their values changed during mining operations to the initial values.

Comparison of Brazilian tensile strength with uniaxial tensile strength is presented. It is noted that on the basis of only statistical processing, it is possible to obtain only rough estimates of direct tensile strength from the measured Brazilian strength. To agree on these values, models that take into account the structure of the material should be used. Taking into account the biaxiality of the stress field, which leads to a decrease in Brazilian strength compared to direct tensile stretch, and considering the nonuniformity of tensile stresses causing the opposite effect, it is possible to correlate the values of tensile strength measured by different methods.

The necessity of expanding the possibilities for controlling the explosive action to obtain a uniform rational fragmentation of the run-of-mine with a minimum yield of oversized and fine low-grade fractions is substantiated. The methodological problems of applying the smoothed particle method for 3D modeling and studying the patterns of dynamic loading of a rock mass, the uniformity and intensity of crushing in different explosive zones, as well as problems of two- and three-dimensional model calibration are considered. The method is calibrated by simulating the fragmentation process by an explosion in comparison with experimental results on blasting rock samples during the explosion of an elongated borehole charge. Work was carried out to study the influence of drilling and blasting parameters and kinetics of energy release on the intensity and uniformity of fragmentation. The regularities of the effect produced by specific consumption of industrial explosives, the rate of energy release; the distance between boreholes, the diameter of borehole charges, as well as air gap values on the intensity and uniformity of crushing in different explosive zones are determined.