forage d'alignement

Désignations

Codes : pays ou zone où la désignation a cours (CH, FR, DE, EU = Union européenne, INT = usage international). Une désignation barrée est déconseillée.

Définitions

anglais

Line drilling: In this method regular rockdrill holes, about 11/2 inches in diameter, are spaced 4 to 6 inches apart along the perimeter and left uncharged. Larger diameter holes could be placed at greater spacing intervals. The buffer zone between the perimeter holes and the last row of main round holes should be about 8 to 12 inches wide (the buffer distance). The drilled unloaded holes along the periphery alone provide a plane of weakness to which the rock will break readily and cleanly when the round is fired.