Research on crack propagation and rock fragmentation efficiency under spherical tooth dynamic indentation


Rock dynamic indentation is the most basic form of rock dynamic fragmentation, understanding the rock failure mechanism and influence factors of breaking efficiency plays important roles in improving impact drilling efficiency. According to the research achievements of Marshall, the theoretical model of radial crack and lateral crack length considering confining pressure and hydraulic pressure was established, analyzing the influence of confining pressure, hydraulic pressure on crack propagation, and the influence of loading rate on rock fragmentation effect. In addition, the discrete element numerical simulation method was used to study the characteristics of crack formation and propagation and the influence of loading rate on breaking effect under spherical tooth dynamic indentation. The results indicate that theoretical analysis and numerical simulation results are basically identical, with the increase of dynamic load, the damaged area and lateral crack growth, and radial crack initiates from the damaged area and propagates towards the rock free surface, forming rock fragments eventually; under the same dynamic load amplitude and duration, the increase of confining pressure has an inhibitory effect on damaged area, lateral crack, and radial crack, the increase of hydraulic pressure has a promoting effect on damaged area and lateral crack but has an inhibitory effect on radial crack; under the same dynamic load amplitude, rock breaking volume first increases and then decreases with the duration shortening, and when the dynamic load amplitude is 8.5 kN, duration is 1.25 ms, the crushing volume is the largest. The research achievements of this paper can provide reference for understanding dynamic fragmentation mechanism and improving impact drilling efficiency.

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The authors are grateful for the Project Supported by the National Natural Science Foundation of China (No. 51804047 and No. 41672133) and the National Science and Technology Major Project-Horizontal well fracturing design optimization system (No. 2016ZX05023-001).

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Correspondence to Fei Yin.

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Responsible Editor: Liang Xiao

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Deng, Y., Yin, F., Deng, H. et al. Research on crack propagation and rock fragmentation efficiency under spherical tooth dynamic indentation. Arab J Geosci 13, 30 (2020).

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  • Dynamic indentation
  • Crack propagation
  • Loading rate
  • Rock breaking
  • Discrete element