Method and equipment for constructing micropiles in soil

Abstract

A method and the corresponding equipment for constructing concrete micropiles of the type used for soil consolidation, which involves the use of a drilling rod which also acts as reinforcement for the pile, and injection of cement grout directly during drilling, the injection being performed from the surface downwards, that includes the following stages: soil drilling with a rod consisting of a drilling bar fitted at the tip with a bit equipped with nozzles, and simultaneous high-pressure injection of grout through said nozzles; when the bar has fully penetrated into the soil, connection of a second bar by means of a sleeve coupling and continuance of drilling with simultaneous grout injection; when the design depth has been reached, detachment of said rod, which is left in the ground to act as reinforcement for the pile thus constructed.

1 ) Method for the construction of micropiles in soil, whereby a hole is drilled and filled with grout and steel reinforcement is inserted into said hole, characterised in that said method includes simultaneous drilling and grout injection. 
   
   
       2 ) Method as claimed in  claim 1 , characterised in that drilling and grout injection are performed from the surface to the bottom of the hole. 
   
   
       3 ) Method as claimed in  claim 2 , characterised in that drilling is performed with a rod which acts as reinforcement for the micropile, while grout is injected at high pressure at the same time, along said rod  1 , and exits from a nozzle in the bit fitted at the distal extremity of the rod. 
   
   
       4 ) Method for the construction of micropiles, characterised in that it includes the following stages:
 soil drilling with a rod consisting of a drilling bar fitted at the tip with a bit equipped with nozzles, and simultaneous high-pressure injection of grout through said nozzles;   when the bar has fully penetrated into the soil, connection of a second bar by means of a sleeve coupling and continuance of drilling with simultaneous grout injection;   when the design depth has been reached, detachment of said rod, which is left in the ground to act as reinforcement for the pile thus constructed.   
   
   
       5 ) Equipment for the construction of micropiles with the method as claimed in  claim 4 , characterised in that it includes a drilling rod fitted at its tip with a bit equipped with one or more outwardly-directed nozzles, and means designed to direct grout at high pressure towards said nozzles, passing inside said rod. 
   
   
       6 ) Equipment as claimed in  claim 5 , characterised in that said rod consists of a plurality of self-drilling bars connected via sleeve couplings designed to withstand very high pressures. 
   
   
       7 ) Apparatus as claimed in  claim 6 , characterised in that said rod is fitted with a bit equipped with at least one pair of nozzles with different inclinations, for injection of grout. 
   
   
       8 ) Apparatus as claimed in  claim 7 , wherein said nozzles have an inclination of 30° and 60° respectively.