Home – Home – Jornals – Advanced Search

The author discusses the deformation kinematics method using the concept of displacement of material planes in a medium. Displacements of planes can be described by two vector fields of displacement or, by way of alternative, by one tensor field which is a field of relative displacement of planes. This is an asymmetric tensor, and its components are uncorrelated by Saint-Venant’s compatibility conditions. This approach recovers an “equality” between the kinematic-based and force-based descriptions of deformation in a medium. The adopted notion of stresses relates to the forces that affect planes inside a body, and the notion of deformation relates to the change of distances between pairs of points. The article gives a case-study of modeling an initially isotropic geomedium using this approach.

Experimental research determined the concentration zones of seismic events and their sources in operating Taimyr Mine. The features of formation and spreading of these zones are assessed. The influence of mined-out void volume on total energy of seismic events before and after flooding and dewatering of mines is analyzed, which allows predicting the level of seismic hazard during further mining.

The ore drawing procedure of the synchronous filling shrinkage mining method is simulated using PFC software. Isolation layer thickness A, isolation layer interface friction factor B , ore particle friction factor C, particle radius D and wall friction factor E are chosen as the five influencing factors of the orthogonal test, along with the characteristics of the orthogonal test and force chain parameters. The findings demonstrate that the primary and secondary order of each factor impact on the orthogonal test index is D>C>A>E>B. The best test configuration was A₁ B₂ C₃ D₃ E₃, with the relevant factors being thickness 0.003 m, isolation layer interface friction factor 0.5, particle friction factor 0.8, particle radius 0.008 m and wall friction factor 0.8.

The article describes inertial impact fracture of geomaterials using a rotary hammer drill. The capabilities of the tool in underground large-hole drilling are discussed. The authors present the procedure and results of the lab-scale testing of influence exerted by different combinations of rotational and linear path velocities of the rotary hammer drill on the strength of current taken by working tools and on the shock vibration velocity of supporting members of the rotary hammer drill. The rational ranges of these velocities, such as the process of fracture runs at the least energy input and minimum impact on the working tools, are determined.

The experimental research assessed the influence exerted by the parameters of cutting process and cutting tool on the loads in cutting hard inclusions in rocks. It is found the in central cutting of hard inclusions, the maximal loads on a cutting pick depend on the width and depth of a cut, and on the cutting pattern, and are independent of the cutting velocity. The increase in the width of the cutting point of a cutting pick contributes to an increase in the peak and average-peak forces of cutting and feed, while the lateral loads in cutting hard inclusions by cutting picks with a flat face depend only on the depth of cut. The peak feed forces essentially depend on the shape of the cutting point of a cutting pick, and the cutting force depend on the angle of cutting. The decrease in the wedge angle of the face of a cutting pick reduces the peak forces of cutting and feed, while the lateral loads increase.

To increase the efficiency of gas extraction drilling in coal seams, screw drilling tools used in petroleum-related operations were introduced instead of common bottom-hole combination drilling tools. According to the Box-Behnken experimental design principle, the significance of three main construction factors on the drilling efficiency is: the flow rate > pump pressure > feed force. The optimized drilling parameters were used to conduct a field test in Wangzhuang coal mine of Shanxi Lu’an Group. The results showed that the drilling efficiency of screw drilling increased by 39.08% and the drilling slag discharge increased by 48.28% compared with the conventional rotary drilling technique, which significantly improved the construction efficiency of coal seam drilling and is expected to reduce the gas treatment cycle and cost of coal seams to a significant extent.

The authors have revealed and compared the internal and external parameters that form a multi-element loop system (dimension chain) of a roller cone drill bit. The article presents procedures for the probability calculation of a dimension chain of the tool dimeter, calculation of the tool diameter error because of the rotation of the cone drill bit on the bit leg, and for the calculation of eccentricity error of gage cones relative to the axis of the fitting thread for three- and four-cone drill bits. It is recommended to revise the values of dimensional tolerance for roller cone drill bits and to amend related normative and technical documentation.

The article reports the research of composition and properties of loparite concentration tailings at the Umbozero plant closed in 1999. During the research, samples of tailings were taken in the surface layer and at depth, using the method of cutting ring. The geological and engineering properties of the tailings were investigated, and the sizing, chemical, X-ray phase and radionuclide analyses were performed. The research revealed heterogeneity in material constitution and properties of the test tailings. The mineral composition of the tailings is dominated by nepheline, and by K and Na feldspars. Loparite is detected by the X-ray phase analysis at one of the four test sites of the tailings pond, and its content increases in the fine fraction. The analysis of radionuclides shows the presence of radium and thorium in the test concentration tailings.

The research focuses on usability of tailings from the Talmovskie Peski and Ursk dumps in the Kemerovo Region as a manmade source of barite after suitable recovery and processing. Mineralogical, geochemical and typomorphic characteristics of barite are assessed from morphology, mineral associations, content and grain size distribution. The technological studies are accomplished, and barite concentrates are obtained from the test tailings by gravity separation and flotation. The concentrates are assessed with respect to barite content with a view to using the concentrates as a weighting material as per the USSR State Standard GOST 4682-84. The barite recovery potential of tailings from the Talmovskie Peski and Ursk dumps is evaluated.

The authors analyze convection-induced stratification of air flows in an inclined drift with an intense heat emission source. The research methodology included 3D numerical modeling of nonstationary aero-thermodynamic processes in an inclined drift and in an adjoint horizontal drift. The article describes three possible scenarios of convection-induced air flow stratification in an inclined drift depending on heat emission intensity. The dependence of the critical heat rate of the heating source on the initial depression and incline of the drift is determined. The pressure difference-mass air flow relationship in the inclined drift is analyzed at different heat emission intensities using the 3D numerical model and a 1D network model. Description of underground mine fires using 1D models requires empirical relationships of air drag, average air density and air flow rate.