Method and Apparatus for Drilling a Large -Diameter Hole in Ground

The present invention relates to a large-diameter ground excavation method and apparatus. This, combined with the hammer drill (40) attached to the lowest end of the rod 104 are assembled in multiple stages in the supporting means on the ground, the simultaneous rotation is possible with the vertical relative movement is possible vertical key structure (42, 43) comprises a pilot hammer drill and reamer hammer drill, and drilling operations when the hammer drill 40 while rotating the excavating first to a depth (d) given a pilot hole of a small diameter (w) is lowered to the pilot hammer drill raised to its original position after one and then the operation is repeated by the step of drilling a hole in the predetermined depth (d) of large diameter (W) is lowered to the reamer hammer drill. In this way, a single hammer in rock drilling operations, as well as be able to perform the drilling work of the early aperture possibly non-perforated, and can be a relatively large diameter drilling is also in a small drilling equipment, the drilling work is shortened and it provides effects such that it becomes an easy task, and further drilling to maintain verticality more accurately. Large, digging, drilling, pilot, hammer drills, drill bits, roller, key