Expanded Tip Pile

Abstract

Methods are provided for introducing unhardened highly expansive grout into the bottom of a formed shaft in the earth and subsequently forming the pile above the grout. The expansion of the hardening grout, after the curing of the pile, generates expansion stress on the surrounding soil and upwardly directed force to the pile. Methods of pile load capacity testing use expansive grout to generate a test load.

1 . Methods of forming a pile in the earth comprising:
 forming a vertical shaft in the earth;   introducing a volume of highly expansive grout (HEG) into the shaft;   introducing unhardened concrete into the shaft to form a pile above and connected to the volume of HEG;   delaying the hardening of the HEG until the concrete is hardened;   such that expansion of the HEG during hardening generates a uplifting stress on the pile.   
     
     
         2 . A method, according to  claim 1 , and wherein:
 the step of delaying the hardening of the HEG comprises delaying the hardening of the HEG by a period in the range of one to two days.   
     
     
         3 . A method, according to  claim 1 , and wherein:
 the step of delaying the hardening of the HEG comprises introducing a chemical agent to the unhardened HEG.   
     
     
         4 . A method, according to  claim 1 , and further comprising:
 introducing HEG into a carrier to form an assembly; and wherein,   the step of introducing a volume of HEG into the shaft comprises:
 placing the carrier into the shaft. 
   
     
     
         5 . A method, according to  claim 4 , and further comprising:
 combining multiple layers of fabric to form the carrier.   
     
     
         6 . A method, according to  claim 5 , and wherein:
 the fabric comprises glass fibers.   
     
     
         7 . A method, according to  claim 4 , and wherein:
 the assembly comprises fifty percent HEG.   
     
     
         8 . A method, according to  claim 1 , and further comprising:
 obtaining stress data between the HEG and the concrete, and deflection data defining movements of the pile; and   determining a pile load capacity.