| Summary: | In the present study, a 3D FEM of compound percussive system considering a loading–unloading cycle was employed to simulate the dynamic single-cutter-rock interaction. By conducting the sensitivity analysis, the effects of the impact velocity of cutter, the dynamic load amplitude, the ratio μ of torsional impact to axial impact frequency on the cutting force and penetration depth were investigated. Moreover, a range of simulations were conducted on the stratum lithology (Granite, Marble and Sandstone). As revealed from the results, the cutting forces increase first and then decrease rapidly with the increase in the torsional impact velocity. Besides, the amplitude of the cutting force in the simulation of duration time was improved. The larger the dynamic load, the faster the cutting forces will reach the peak. The penetration depth curve exhibits the step characteristics and increases with the dynamic load amplitude and impact velocity amplitudes. With the ratio μ increasing continuously (μ<2), the amplitude of cutting force and penetration depth tends to be improved. However, the relationship between the torsional and axial impact frequencies might have an optimal value. The stronger rock achieved a higher penetration depth. The penetration depth and the penetration rate could be obtained regardless of rock types when μ=1.5. The penetration rate will demonstrate an improvement of 49.02% under the axial impact and 35.92% under the torsional impact. Finally, the field applications of compound percussive drilling is conducted. The numerical simulation results agree well with field experiment results, with an average accuracy of 91.2% of well Guo X-8 and 96.7% of well Pu X-32, respectively. The study on the mechanism of the compound percussion drilling technology for rock breaking theoretically supported the subsequent development and optimization of the tools.
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