Abstract: An earth auger is disclosed in which an auger shaft is provided with freely expansible and contractible rotary blades in such manner that said rotary blades may expand automatically when said auger shaft is rotated in the foward direction and may contract automatically when said auger shaft is rotated in the reverse direction. Also a method for driving piles and the like is disclosed which comprises the steps of positioning a pile or shoring adjacent to said auger shaft and above said blades, advancing said pile or the like into an earth bore excavated by said rotary blades, and filling said bore excavated by the rotary blades with mortar or the like.

Abstract: A method for establishing an anchor inside of a retaining wall is described; in which an auger bore is excavated through said retaining wall with an earth auger and thereafter by reversing the rotation of said earth auger an enlarged bore is formed at the extreme end portion of said auger bore; and in which an auger head and an auger shaft are separated from each other to leave an anchor plate formed integrally with said auger head as well as a rod connected to said anchor plate within the enlarged bore and the auger bore, and then mortar is filled in these bores to establish an anchor made of concrete in the earth. In one preferred embodiment of the invention, the rod and the anchor plate are connected to each other by fastening with a nut, this connecting portion being enclosed in a box, and also the peripheral surface of said rod is coated with a synthetic resin film, whereby a provision is preliminarily made such that the rod may be easily extracted from the anchor after the use of the anchor has ended.

Abstract: A method for establishing an anchor inside of a retaining wall is described; in which an auger bore is excavated through said retaining wall with an earth auger and thereafter by reversing the rotation of said earth auger an enlarged bore is formed at the extreme end portion of said auger bore; and in which an auger head and an auger shaft are separated from each other to leave an anchor plate formed integrally with said auger head as well as a rod connected to said anchor plate within the enlarged bore and the auger bore, and then mortar is filled in these bores to establish an anchor made of concrete in the earth. In one preferred embodiment of the invention, the rod and the anchor plate are connected to each other by fastening with a nut, this connecting portion being enclosed in a box, and also the peripheral surface of said rod is coated with a synthetic resin film, whereby a provision is preliminarily made such that the rod may be easily extracted from the anchor after the use of the anchor has ended.

Abstract: An earth auger is disclosed in which an auger shaft is provided with freely expansible and contractible rotary blades in such manner that said rotary blades may expand automatically when said auger shaft is rotated in the forward direction and may contract automatically when said auger shaft is rotated in the reverse direction. Also a method for driving piles and the like is disclosed which comprises the steps of positioning a pile or shoring adjacent to said auger shaft and above said blades, advancing said pile or the like into an earth bore excavated by said rotary blades, and filling said bore excavated by the rotary blades with mortar or the like.