Patent ID: 8910729
Filing Date: 2014-12-16
Classification: E21B

Abstract:
1. A method for drilling a hole in the ground, the method comprising: installing a hammer drill on a drilling apparatus, the hammer drill comprising a pilot hammer drill and a reamer hammer drill coupled to each other through a key structure disposed therebetween and in the vertical direction, the key structure being configured to allow the pilot and reamer hammer drills to simultaneously rotate, and to move up and down relative to each other and simultaneously with the rotation of the pilot and reamer hammer drills; lowering the pilot hammer drill to drill a pilot hole to a predetermined depth, the pilot hole having a smaller diameter than that of the hole; lifting up the pilot hammer drill to an original position; and lowering the reamer hammer drill to drill the hole, enlarging the pilot hole to a larger diameter, to the predetermined depth, wherein the pilot hammer drill includes at least one reverse circulation pipe configured to discharge soil and rock debris generated during the drilling of the hole outside the hole, and an end of the at least one reverse circulation pipe is located on a bottom of the hammer drill.