Apparatus and method for forming a support column in soil

Abstract

The present invention provides a method of forming a support column in soil using a reverse circulation down-the-hole hammer apparatus. The method includes drilling a hole with a reverse circulation down-the-hole hammer apparatus having a drill string with a return outlet and a down-the-hole hammer, and forming a column of mortar-like substance by pumping a mortar-like substance down the return outlet while lifting the apparatus out of the hole.

What is claimed is:  
     
         1 . A method for forming a support column in soil comprising: 
 drilling a hole with a reverse circulation down-the-hole hammer apparatus having a down-the-hole hammer connected to a drill string with a return outlet; and    forming a column of mortar-like substance by pumping a mortar-like substance down the return outlet while lifting the apparatus out of the hole.    
     
     
         2 . The method of  claim 1 , wherein the mortar-like substance is selected from the group consisting of grout, mortar, concrete, and mixtures thereof.  
     
     
         3 . The method of  claim 2 , wherein the mortar-like substance is concrete.  
     
     
         4 . The method of  claim 1 , wherein the lifting of the apparatus out of the hole is initiated about 30 seconds after the mortar-like substance is pumped into the return outlet.  
     
     
         5 . The method of  claim 1 , wherein the apparatus is lifted out of the hole at a vertical rate that is substantially equivalent to the vertical fill rate of the mortar-like substance into the portion of the hole evacuated by the apparatus.  
     
     
         6 . The method of  claim 1 , further comprising the step of installing a metal reinforcing structure into the hole filled with the mortar-like substance before it hardens.  
     
     
         7 . The method of  claim 6 , wherein the metal reinforcing structure is selected from the group consisting of steel rods, steel I-beams, steel cages, pipe, channel iron, and combinations thereof.  
     
     
         8 . The method of  claim 7 , wherein the metal reinforcing structure is a steel I-beam.  
     
     
         9 . The method of  claim 1 , wherein the apparatus further includes a pipe casing placed behind the down-the-hole hammer and enveloping the drill string.  
     
     
         10 . The method of  claim 9 , wherein the pipe casing is connected to the down-the-hole hammer.  
     
     
         11 . The method of  claim 10 , wherein the pipe casing is connected to the back of the down-the-hole hammer.  
     
     
         12 . The method of  claim 10 , wherein the pipe casing is connected to and envelopes at least a portion of the down-the-hole hammer.  
     
     
         13 . The method of  claim 9 , wherein the pipe casing is connected to the drill bit.  
     
     
         14 . An apparatus for drilling a hole in soil and forming a support column, the apparatus comprising, 
 a down-the-hole hammer having a back end and a drill bit end;    a drill string having an inner passageway, one end of the drill string connected to the back end of the down-the-hole hammer and the other end of the drill string connected to a cuttings discharge swivel; and    a mortar-like substance intake valve attached to the cuttings discharge swivel.    
     
     
         15 . The apparatus of  claim 14 , wherein the intake valve comprises, a body portion in fluid communication with the cuttings discharge swivel at one end and a debris discharge hose at the other end, and an intake portion in fluid communication with a source of a mortar-like substance and the body portion of the intake valve.  
     
     
         16 . The apparatus of  claim 15 , wherein the intake portion of the intake valve is positioned to the body of the intake valve to form an angle that is less than about 90 degrees.  
     
     
         17 . The apparatus of  claim 16 , wherein the angle is less than about 70 degrees.  
     
     
         18 . The apparatus of  claim 14  further comprising a pipe casing connected to the down-the-hole hammer and enveloping the drill string.  
     
     
         19 . The apparatus of  claim 18 , wherein the pipe casing is connected to the back of the down-the-hole hammer.  
     
     
         20 . The apparatus of  claim 18 , wherein the pipe casing is connected to and envelopes at least a portion of the down-the-hole hammer.  
     
     
         21 . The apparatus of  claim 14 , further comprising a pipe casing connected to the drill bit.