pochage

CONT: Le ""pochage"" consiste à faire exploser au fond d'un trou, en les renouvelant plusieurs fois, de petites charges d'explosifs. On a parfois recours à ce procédé dans les terrassements de rocher ou dans les carrières pour élargir à sa base un trou de mine de petit diamètre, afin d'y concentrer une plus forte charge d'explosif.

CONT: ""Bulling"" or chambering of holes. The bottom of a small diameter borehole (such as diamond drill or wagon drill hole) may be enlarged by lighting and dropping a gelatine dynamite safety fuse primer into the hole. The burden is of course, too great for this small charge to break the ground. Its effect is to pulverize the rock in the vicinity and to expel it from the mouth of the hole in the form of dust. Meanwhile, the bottom of the hole has been increased in diameter in the form of a bulbous-shaped chamber, which will then accommodate a larger quantity of explosive. Care should be taken to allow the bottom of the hole to cool down before adding further explosives. The operation is variously called ""bulling"" or ""chambering"" or ""springing"". The method has been used chiefly in quarry work on bench holes.