We present the articles of the third issue of scientific journal "Mining Science and Technology” (Russia) for 2024:

The performed study allowed to develop a model of hyperbolic time-distance curve of GPR impulses reflected from a local feature located in a rock mass with an arbitrary number of layers. Practical application of the obtained results in studies aimed at automated determination of electrophysical properties of rocks and soils by hyperbolic time-distance curves will allow to create a database with up-to-date information on dielectric permittivity of rocks.

For more information, see the article:

🔥 Sokolov K.О. Model of time-distance curve of electromagnetic waves diffracted on a local feature in the georadar study of permafrost zone rock layers. Mining Science and Technology (Russia). 2024;9(3):199-205. https://doi.org/10.17073/2500-0632-2023-05-118 🔥

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#inenglish #MST #model #rock_mass #rock #dielectric_permittivity #velocity #hyperbola #layer #georadar #permafrost_zone #gprMax

How to reduce the output of fines rate during block stone extraction by drilling and blasting?

At many quarries for the extraction of building stone there is a problem of increased output of fines after all stages of crushing and grinding, which leads to a decrease in the economic performance of mining enterprises. The fine fraction is formed by the crushing / grinding of prefractured rock mass. Reducing the intensity and size of the prefracture zones will lead to a solution to the problem at hand. It was established that the greatest influence on the shape and duration of the blast pulse is exerted by the velocity of explosive detonation. As the detonation velocity decreases, the peak pressure of the head part of the pulse decreases, and the duration of its rise increases, while a low-amplitude pulse of long duration contributes to better crushing of a rock mass with the least effect of prefracture. Using explosives with a reduced detonation velocity allows reducing the “surplus” impact on a rock mass and thus reducing the intensity of prefracture in the zone of controlled crushing during a blast. This is because the individual pieces will be weakened to a lesser extent after a blast and as a result, the yield of undersize when crushing rock into crushed stone will be reduced.

For more information, see the article:

📌 Khokhlov S.V., Vinogradov Yu.I., Makkoev V.A., Abiyev Z.A. Effect of explosive detonation velocity on the degree of rock pre-fracturing during blasting. Mining Science and Technology (Russia). 2024;9(2):85-96. https://doi.org/10.17073/2500-0632-2023-11-177

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#inenglish #MST #prefracture #crushing #blast #stress #microfracture #fracture #density #detonation #velocity #fines

What are the specific characteristics of ground-penetrating radar (GPR) in permafrost, and how can its effectiveness be improved?

The most important parameters for electromagnetic wave propagation in a medium are the wave’s speed and specific attenuation. The propagation speed of electromagnetic waves generally depends on the relative permittivity, the relative permeability, and the frequency of the applied field. On the example of a permafrost zone rock mass containing a layer of unfrozen rocks, the effect of the thicknesses of rock layers and their relative dielectric permittivity on the apparent dielectric permittivity resulting from the calculation of the theoretical hyperbolic time-distance curve was shown. The conditions under which it is impossible to determine the presence of a layer of unfrozen rocks from a hyperbolic time-distance curve are also presented. The results obtained in the course of the study are of great importance for the development of methodological support of GPR for determining electrophysical properties of rocks, which will increase the reliability of the assessment of their physical and mechanical properties, especially in the area of permafrost occurrence. Practical application of the obtained results in studies aimed at automated determination of electrophysical properties of rocks and soils by hyperbolic time-distance curves will allow to create a database with up-to-date information on dielectric permittivity of rocks.

For more information, see the article:

📌 Sokolov K.О. Model of time-distance curve of electromagnetic waves diffracted on a local feature in the georadar study of permafrost zone rock layers. Mining Science and Technology (Russia). 2024;9(3):199-205. https://doi.org/10.17073/2500-0632-2023-05-118

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#Inenglish #MST #georadar #electromagneticwaves #hyperbolictimedistancecurve #layeredmedium #dielectricpermittivity #permafrostzone #propagationvelocity #localfeature #multilayerrockmass #geometricoptics #syntheticradargrams #computersimulation #thawedrocks #relativeerror #horizontallylayeredmedium #apparentvelocity #materialpart #physicalmechanicalproperties #automationsearch #georadarmeasurements #velocity #hyperbola #layer #gprMax

❓ Can the setback distance of a mine ventilation duct be increased without losing efficiency?

New research has proven: even with a 21-meter setback from the working face, the air jet maintains its effectiveness, fully ventilating the dead-end drift.

🔹 Key findings:

✔️ Experiments conducted in an actual 29.2 m² cross-section drift with five setback variants (10-21 m)
✔️ 21.75 m/s jet velocity ensured proper ventilation even at maximum distance
✔️ Results verified through computer modeling
✔️ Derived equation correlates face velocity with drift geometry

🔹 Why it matters:

The discovery allows safely increasing duct setback to 20m for large cross-section drifts, simplifying mining operations.

For more information, see the article:

📌 Kamenskikh A.A., Faynburg G.Z., Semin M.A., Tatsiy A.V. Experimental study on forced ventilation in dead-end mine working with various setbacks of the ventilation pipeline from the working face. Mining Science and Technology (Russia). 2024;9(1):41-52. https://doi.org/10.17073/2500-0632-2023-08-147


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#InEnglish #MST #MineVentilation #DeadEndFace #ForcedVentilation #VentilationDuctSetback #FieldExperiment #NumericalSimulation #AirflowPatterns #MiningTechnology #MiningSafety #Mining #Ventilation #Safety #DeadEnd #Airflow #FieldStudy #NumericalModeling #JetFlow #Turbulence #MineSafety #ForcedVentilation #Pipeline #CrossSection #Velocity #Vortex #StagnantZone #ANSYS #CFD #Regulations #Research #Engineering

We present the articles of the first issue of scientific journal "Mining Science and Technology” (Russia) for 2025:

Scientists conducted laboratory tests according to the International Society for Rock Mechanics (ISRM) methodology to investigate fracture toughness at interfaces between gypsum stone and sand-cement mortar. The fracture toughness coefficient K_IC was determined using cylindrical specimens 40 mm in diameter and 150 mm long with a V-shaped notch, tested in three-point bending. Results showed that the average KIC value for the rock-concrete interface was only 0.323 MPa×√m – 4 times lower than for pure gypsum (1.327 MPa×√m) and 2.5 times lower than for concrete specimens (0.858 MPa×√m). Interestingly, the formation of a calibrated fracture during testing caused a 30% increase in the internal mechanical loss factor Q⁻¹, revealing new possibilities for fracture toughness evaluation using resonance methods. These findings have important practical implications for the design, operation and monitoring of industrial mining facilities containing rock-concrete interfaces.

For more information, see the article:

📌 Voznesenskii А.S., Ushakov E.I., Kutkin Ya.O. Fracture toughness of rock-concrete interfaces and its prediction based on acoustic properties. Mining Science and Technology (Russia). 2025;10(1):5-14. https://doi.org/10.17073/2500-0632-2024-10-316

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#InEnglish #MST #rocks #concrete #gypsum #flintstone #interface #properties #fracturetoughness #acoustics #study #testing #acousticmeasurements #elasticwaves #velocity #losses #prediction #strain #rockmechanics #geophysics #ISRM #KIC #Qfactor #monitoring #strength #failure #cement #science #technology #RSFgrant #nondestructivetesting #resonancemethod #mining #engineeringsolutions

💥 How does the detonation velocity of explosives affect rock fracturing?

In quarries for building stone extraction, up to 30% of the rock turns into fines after blasting and crushing, reducing economic efficiency. One of the key factors is the prefracture zones formed during explosive detonation.

🔬 What was studied?

1️⃣ Explosive detonation velocity (ranging from 2 to 5.2 km/s).
2️⃣ Stresses in the rock mass during blasting.
3️⃣ Microfracturing using X-ray microtomography.

📊 Results:

✔️ The size of the prefracture zone increases from 33R to 77R (where R is the charge radius) as detonation velocity rises.
✔️ Microfracture density (N) depends on the distance from the charge:
• Near zone (10R): from 5,000 to 13,800 pcs/cm³ (exponential growth).
• Far zone (70R): from 0 to 200 pcs/cm³ (linear growth).

💡 Practical conclusions:

➡️ Using explosives with reduced detonation velocity minimizes prefracture zones and decreases fines yield.
➡️ Optimizing blasting parameters allows controlled rock fragmentation and increases the output of marketable fractions.

For more information, see the article:

📌 Khokhlov S.V., Vinogradov Yu.I., Makkoev V.A., Abiyev Z.A. Effect of explosive detonation velocity on the degree of rock pre-fracturing during blasting. Mining Science and Technology (Russia). 2024;9(2):85-96. https://doi.org/10.17073/2500-0632-2023-11-177

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#InEnglish #MST #Prefracture #CrushingToRubble #BlastStresses #Microfracture #FractureDensity #DetonationVelocity #FinesYields #Rock #Blast #Explosives #Quarry #Stone #Fines #Stress #Wave #Charge #Radius #Density #Cracks #Fragmentation #Impact #Velocity #Energy #Zones #Array #Control #Efficiency #Laboratory #Tomography #Results #Optimization #Parameters #Marketable #Output