Mechanism experimental study of rock breaking assisted with high frequency harmonic vibration and impaction

Key words:  high frequency harmonic vibration  rock breaking model  factor analysis  indoor experiment

Abstract:

A new and efficient rock breaking technique assisted with high frequency harmonic vibration and impaction was developed for drilling in complicated and hard formations. In this study, physical and mathematical simulation models were established to study the process rock breaking based on the theory of vibration. The mathematical model was solved by the MATLAB software, and the effects of various parameters on rock vibration under the harmonic vibration excitation were analyzed. The effect of the vibration and impaction technique on rock breaking has been verified through indoor experiments. The experimental results show that the penetration rate under the harmonic vibration excitation is increased by 13.2％. The penetration rate increases with the increase of the dynamic excitation force, while rock 's stiffness, damping and critical force have a negative effect on penetration rate. The more closer between the excitation frequency and the natural frequency of rock, the greater the penetration rate is. Nevertheless, the penetration rate also increases with the increasing of the weight on bit and rotation speed.