Pile formation

Abstract

Forming concrete piles with an enlarged base for structural foundations for buildings. The invention involves: a) drilling a bore hole with an auger; (b) pumping fluid concrete into the bore hole through a channel in the auger whilst retracting the auger from a lower portion of the bore, such that the lower portion of the bore becomes filled with a volume of fluid concrete; (c) applying a 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, thereby increasing the diameter of the lower portion of the bore; (d) retracting the auger from the remainder of the bore whilst pumping further concrete into the bore, such that the bore fills with concrete and forms a concrete pile with an enlarged base. The enlarged base area provides greater load bearing capacity.

1 . A method of forming a concrete pile in the ground using an auger having a stem with a fluid channel communicating between an inlet towards the top end of the stem and an outlet located towards the step tip, the method comprising the steps of: 
 (a) creating a bore hole by screwing the auger into the ground in an axial direction;    (b) pumping fluid concrete into the bore hole through the fluid channel in the stem whilst retracting the auger from a lower portion of the bore, such that the lower portion of the bore becomes filled with a volume of fluid concrete;    (c) applying a 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, thereby increasing the diameter of the lower portion of the bore; and,    (d) retracting the auger from the remainder of the bore whilst pumping further concrete into the bore, such that the bore fills with concrete and forms a concrete pile.    
     
     
         2 . A method of forming a concrete pile as claimed in  claim 1 , wherein in step (c) the auger is reinserted into the lower portion of the bore by screwing the auger into the concrete.  
     
     
         3 . A method of forming a concrete pile as claimed in  claim 1  or  claim 2 , wherein a pumping pressure is continuously applied with a pump during steps (b) to (d).  
     
     
         4 . A method of forming a concrete pile as claimed in  claim 3 , wherein the pumping pressure is in the range 0.5 bar to 1 bar.  
     
     
         5 . A method of forming a concrete pile as claimed in any previous claim, wherein the auger is rotated when it is retracted at least partially from the bore.  
     
     
         6 . A method of forming a concrete pile as claimed in any previous claim, wherein concrete is continuously pumped into the bore as the auger is being retracted.  
     
     
         7 . A method of forming a concrete pile as claimed in any previous claim, wherein the stem of the auger has a cylindrical shaft portion and a tip portion with at least one upstanding flight arranged thereon in a helical fashion.  
     
     
         8 . A method of forming a concrete pile as claimed in  claim 7 , wherein the tip portion has two flights rotationally displaced by 180 degrees from one another.  
     
     
         9 . A method of forming a concrete pile as claimed in  claim 7  or  claim 8 , wherein at least part of the tip portion tapers to an area of reduced diameter.  
     
     
         10 . A method of forming a concrete pile as claimed in any one of  claims 7  to  9 , wherein the ratio of the maximum radial extend of the upstanding flights from the centre of the auger and the radius of the shaft portion is between 4:3 and 32:30.  
     
     
         11 . A method of forming a concrete pile as claimed in  claim 10 , wherein the ratio is substantially 35:30.  
     
     
         12 . An auger for drilling a bore hole in the ground, comprising a stem with a tapering tip portion, the tapering tip portion having at least one upstanding flight arranged thereon in a helical fashion, and the stem having fluid channel communicating between an inlet towards the top end of the stem and an outlet towards the step tip.  
     
     
         13 . A method of forming a concrete pile in a bore hole in the ground comprising the steps of: 
 (a) filling a lower portion of the bore hole with a volume of fluid concrete;    (b) applying a pressure to the volume of fluid concrete by at least partly inserting an auger into the lower portion of the bore in an axial direction, such that the applied pressure causes the volume of concrete to expand radially, thereby increasing the diameter of the lower portion of the bore;    (c) retracting the auger from the remainder of the bore and filling the remainder of the bore with concrete; and,    (d) allowing the concrete to cure.    
     
     
         14 . A method of forming a concrete pile substantially as herein described with reference to or as shown in the accompanying drawings.  
     
     
         15 . An auger for drilling a bore hole substantially as herein described with reference to or as shown in the accompanying drawings.