A concrete pile with an enlarged base for structural foundations for buildings is formed by drilling a borehole with an auger, pumping fluid concrete into the borehole through a channel (22, figure 3) in the auger whilst retracting the auger from a lower portion of the bore, allowing concrete to fill the resulting void, applying pressure to the volume of fluid concrete by at least partly reinserting the auger into the lower portion of the bore such that the applied pressure causes the volume of concrete to expand radially and increase the diameter of the lower portion of the bore wall 26, retracting the auger from the remainder of the bore whilst pumping further concrete into the bore, such that a concrete pile is formed with an enlarged base that provides a greater load-bearing capacity. The auger comprises a stem with a tapering tip portion 16 that has at least one upstanding flight arranged in a helical fashion; the stem has a fluid channel that communicates between an inlet at the top of the stem and an outlet at the stem tip.
展开▼
