Hard rock drilling technique with abrasive water jet assistance

A dense “boss” in the hole bottom by the conventional rotating mechanical drilling in the hard rock requires a more efficient drilling technique with great stress concentration, easy heat dissipation and slow bit wear. A new kind of hard rock mechanical drilling technique with the abrasive water jet assistance is developed for this issue, and the abrasive water jet is introduced to erode the “boss” for a “pilot hole” because of the lower rock...