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Experimental studies and analysis of silicate inclusions testify to the magmatic genesis of part of chromian spinel from the Triassic deposits of the northeastern Siberian Platform. The compositions of melt inclusions in the chromian spinel show the participation of alkaline (potassic) magmas in their crystallization. Most data indicate the presence of magmatic systems similar to melts in the Guli ultrabasic massif in the northern Siberian Platform. Studies of the distribution of trace and rare-earth elements in the melt inclusions show the existence of several magmatic systems. These are, first of all, magmas that formed Guli-type ultrabasic massifs and gave rise to meimechites and picrites in the Maimecha-Kotui province. There are also plume-related magmatic systems with kimberlites, lamprophyres, and/or other continental “hot spots”. The composition of the melt inclusions suggests the existence of several types of the primary sources of chromian spinel in the northeastern Siberian Platform, which confirms the earlier data on the heterogeneous composition of the deposits of the diamondiferous Carnian (Upper Triassic) Stage. Applying computer modeling with the well-known COMAGMAT, PETROLOG, and WinPLtb programs as well as the Ol-Sp geothermometers based on the melt inclusions in chromian spinel from the Triassic deposits of the northeastern Siberian Platform, we have determined the P - T conditions of crystallization of minerals in the igneous rocks being the sources of the examined chromites. The temperature of liquidus crystallization of chromian spinel is 1324-1275 ºC. The P - T conditions of formation of olivine and clinopyroxene inclusions in it are estimated at ca. 4.5-4.1 kbar, 1510-1150 ºC and 3.2-1.0 kbar, 1285-1200 ºC, respectively.

Two schemes of shock tunnels and results of experimental investigations of cumulation of liquid cylindrical shells in a rotating system are presented. The first scheme is used to study one-dimensional compression (classical cumulation) of a rotating cylindrical shell under explosive loading by an annular piston. Experimental results are estimated with the use of the model of dynamics of one-dimensional cylindrical cumulation in a quiescent unbounded liquid. In the second scheme, a bore jump is found on the inner surface of the rotating gas cavity; this structure is formed by the piston in the case of shock loading of the gas cavity and its downstream propagation along the axis of symmetry.

An equation of the dynamics of formation and radiation of a quasi-empty oscillating cylindrical cavity in a fluid is derived for the first time with due allowance for the changes in the velocity of sound and the volume fraction of cavitation nuclei. A dimensionless formulation of the problem is proposed and analyzed under the condition of identical pressures in the cavitation zone and inside the cylindrical cavity at its boundary. As a result, a dynamic relationship between the volume fraction (velocity of sound) in the cavitation zone and the radius of the cylindrical cavity is found.

The paper studies the segmented flow modes of immiscible liquids in microchannels with T- and X-shaped inputs for 3D printing technologies. On the basis of the flow visualization results, mode maps with a distinguished area of stable plug flow are constructed. A fair coincidence of the maps built on the basis on the superficial flow velocities is revealed, and the influence of the channel input on the boundaries of flow modes is shown to be insignificant. When using a less viscous carrier phase, the region of a stable plug mode is demonstrated to expand towards higher superficial flow velocities. The separation of microdrops from the trailing edges of plugs is investigated. It has been found that the transition to the separation of microdrops is described in terms of the capillarity number, constructed from the bulk velocity of the phases, and the ratio of phase flow rates. Thus, a range of dimensionless parameters of microchannel devices, suitable for 3D printing of composite materials with specified properties has been determined.

The author focuses on complex loading of a granular material at continuous rotation of the principal strain axes. The described testing procedure reveals the stress dependence on the relative velocity of rotation. It is possible to use the velocity of rotation of a unit volume relative to the velocity of rotation of the principal strain axes in the constitutive equations for a continuum.

The plane and axially symmetric 2D numerical modeling of rock mass blasting is carried out using the Lagrangian tensor-based method. The results are compared with the actual direct measurements of rock mass permeability in the near zone of underground nuclear explosion Dnepr-1 in Khibiny in 1972. The post-explosion permeability of hard rocks is assessable at an admissible accuracy using the calculated shear strain intensity. A case-study of rock mass permeability change assessment in the near zone of blasting of a complex configuration charge is discussed.

The gravity flow of granular materials in axially symmetric convergent channels (V-shaped bunkers) is analyzed using the discrete element method. The symmetrical radial flow becomes unstable under certain conditions, and a space-time structure forms in the medium. The flow becomes essentially nonradial and asymmetric - the material is discretized into blocks, and the field of velocities inside the material becomes discontinuous. Further deformation reduces to relative movement of the blocks as rigid bodies.

In this study, the swelling behavior of sand-bentonite mixtures and pure bentonite are investigated by considering different factors, such as bentonite content in the mixture, specimen preparation method by applying different compactive efforts, and varying effective stress levels. Compaction tests were performed on the specimens of the sand-bentonite mixtures with 10% and 20% bentonite contents and pure bentonite. The maximum dry unit weight and the optimum water content of the specimens with 20% bentonite were relatively higher than specimens with 10% bentonite. Pure bentonite specimens had a lower maximum dry unit weight and higher optimum water content compared to sand-bentonite mixtures. Specimens of the swelling tests were prepared at the optimum water content values. Up to a vertical effective stress of 25 kPa, the mixtures showed a swelling behavior. Under the effective vertical stresses of 50 and 100 kPa, it was evident that the specimens behaved in the compression side. It was seen that the application of either 10 or 25 blows by means of compactive effort in pure bentonite specimens had a neglectible effect on the swelling behavior.

The article describes the rotary drilling modeling using the two-mass system of a drill string with a crush-and-shear hybrid drill bit. The head resistance of rocks on the bit is determined non-linearly: the penetration rate is added with the strength loss in the supporting medium under impact. The scope of the analysis embraces the continuous force generated by the rotating bit and the pulsed impacts by the drill strings at the end-points of the bit-bottomhole detachment. The initial conditions of the post-impact process, which define the initial penetration rate and the speed of the bit, are determined with regard to potential stick-slip effects. The numerical modeling proves that, as against the torsional vibrations, the axial-torsional vibrations of the drill string often result in the chaotic dynamics of drilling.

In this paper, the effect of elevated thermal treatment on the physico-mechanical parameters of Chunar sandstone from Mirzapur district of U.P. was investigated. The studied area is represented geologically by the Vindhyan Supergroup from Meso to Neproterozoic age. Sandstone of Chunar area, Mirzapur, U.P. has been granted the tag of Geographical Indication (GI) under the category of natural goods in 2019. Mechanical strength tests (indirect tensile and uniaxial compressive strength) were performed by a universal testing machine. Samples were treated at elevated temperature in the electric furnace at different temperatures for conducting mechanical and physical tests in each sample and results were recorded. The results suggest that for sandstone, high temperature treatment leads to volume expansion, weight reduction and a decrease in density as well as the reduction in the strength characteristics. Up to 200°C there is an inappreciable increase in indirect tensile strength and compressive strength but after 200°C strength gradually decreases. Beyond 400°C, the P-wave velocities showed a sharp decline due to elevated temperature treatment induced cracks in the heated sandstone.