METHOD TO GENERATE CUTTER CAVITY Russian patent published in 1995 - IPC

FIELD: drilling-disrupting tunnelling. SUBSTANCE: central bore hole is drilled perpendicular to slope surface, and periphery ones of increasing depth are evenly distributed over its circumference and parallel to it. Charges tamped with inertia material are seated in all bore holes. Then the charges are fired consequently corresponding increasing depth of the bore holes with concurrent firing charges in bore holes of equal depth. In so doing the central bore hole and a periphery one are drilled for equal depth. EFFECT: highly effective tunnelling. 4 dwg