AUGER BIT FOR FROZEN FINE-GRAINED SOIL

Abstract : Auger bits 6.5 in. (165 mm) and 9.5 in. (241 mm) in diameter were modified to satisfy military and general engineering requirements for producing holes in frozen soil. A commercial bit was selected since it appeared to need only minor modification. Penetration tests were run in frozen fine-grained soils, one type containing some gravel. Modifications, which primarily involve changes in cutter relief angles, substantially improves performance. Penetration rates were as high as 5 ft/min (1.5m/min), compared to 0-1.4 ft/min (0.04 m/min) for the unmodified bits. Keywords: Augers; Drill bits; Drill design; Frozen soil.