Equipment and method for mixing in loco for the formation of diaphragms

Abstract

Described herein is excavation equipment for mixing in loco excavated soil and for the formation of diaphragms within the excavated hole of the type constituted by a plurality of rods for drilling soil ( 10 ) arranged alongside one another; each rod performs a rotary and translational motion about and along its own axis; supplied along the rods is a thickening fluid that exits with high kinetic energy through nozzles ( 23 and 24 ) made in positions corresponding to bits of a set of bits ( 11 ) located at the free ends of the rods ( 10 ) and rendered fixed in rotation and translation therewith; the bits are interconnected and separated by means of fixed structures ( 16, 16 ′) that guarantee non-interference and maintenance of the distance between them; the bit of each rod ( 10 ) is equipped, at its ends, with disgregating means ( 14 ) and, at the centre, with means ( 18, 21 ) for mixing the soil and said aggregating fluid; the bits are enclosed at least partially within a quadrilateral caisson ( 12 ), designed to line the walls of the excavated hole as the equipment advances with the excavation in the soil; the nozzles ( 23, 24 ) are directed in positions corresponding to the <<dead>> areas of the caisson not reached by the bits ( 14 ).

1 ) Excavation equipment for mixing in loco the excavated soil and for the formation of diaphragms within the excavated hole of the type comprising a plurality of rods for drilling soil arranged alongside one another, each rod performing a rotary and translational motion about and along its own axis; wherein supplied along the rods is a thickening fluid that exits with high kinetic energy through nozzles made in positions corresponding to bits of a set of bits located at free ends of the rods and rendered fixed in rotation and translation therewith; the bits are interconnected and separated by fixed structures that provide non-interference and maintenance of the distance between them; the bit of each rod being equipped, at its ends, with disgregating means and, at the centre, with means for mixing the soil and said aggregating fluid; the bits being enclosed at least partially within a quadrilateral caisson, configured to line the walls of the excavated hole as the equipment advances with the excavation in the soil; the nozzles being directed in positions corresponding to areas of the caisson not reached by the bits.  
   
   
       2 ) The excavation equipment according to claim  1 , wherein the drilling rods are equipped with rotary motion about their own axis in opposed pairs.  
   
   
       3 ) The excavation equipment according to  claim 1 , wherein connected to each rod is a bit of the set of bits comprising, starting from the bottom up: 
 a disgregating blade provided with teeth, designed to remove the underlying soil;    a non-rotating structure for connection between the bits to keep the distance between them fixed;    a first rotating blade with mixing members oriented in the direction of the fixed structure; the fixed structure also being equipped with mixing members in positions interspersed with respect to those of the first blade; and    a second mixing blade being set between the fixed structure and the disgregating blade;    mixing members being positioned under the second blade and similar mixing members being positioned under the fixed structure.    
   
   
       4 ) The excavation equipment according to  claim 3 , wherein the aggregating fluid is sprayed through first radial nozzles, set between the disgregating blade and the first mixing blade, and second radial nozzles, which are oriented in a downward direction under the disgregating blade; both the first and the second nozzles rotating together with the bits.  
   
   
       5 ) The excavation equipment according to  claim 1 , wherein the caisson comprises a perimeter of vertical metal plates that delimit a rectangular section of excavation; the diameter of the blades of the bits being such as to excavate partially overlapping columns of diameter substantially equal to the smaller side of the rectangular section; the areas at the four extreme corners and the areas not excavated by the bits, but comprised within the rectangle, being demolished by the radial jets of aggregating fluid, the position of which in height is at the level of the bottom rim of the perimetral metal plates.  
   
   
       6 ) The excavation equipment according to  claim 1 , wherein the rods are substantially as long as the depth of the excavation that it is intended to be obtained.  
   
   
       7 ) The excavation equipment according to  claim 1 , wherein the rods are substantially shorter than the depth of the excavation that it is intended to obtain.  
   
   
       8 ) The excavation equipment according to  claim 7 , wherein means are provided for controlling the speed of the motors that set in rotation the rods that do not ensure a perfect synchronism; consequently the individual bits of the set of bits have the blades arranged at different heights to prevent any accidental interference, and wherein the motors are located at different heights to facilitate the vertical movements of the device within the mixture of soil and aggregating fluid.  
   
   
       9 ) The excavation equipment according to  claim 8 , wherein the lateral rods are longer than the central ones, so that the central motors are set lower than the lateral ones.  
   
   
       10 ) The excavation equipment according to  claim 9 , wherein the set of bits has two fixed overlapping and parallel structures; consequently the set of bits carried by the left-hand long rod and the one carried by the right-hand short rod are sent back in by the top structure and carried by the bottom structure, wherein the individual bits of the set of bits carried by the right-hand long rod and the one carried by the left-hand short rod are carried by the top structure and sent back in by the bottom one.  
   
   
       11 ) A method for mixing in loco excavated soil during the formation of diaphragms within the excavated hole using equipment according to  claim 1 , wherein the rods advance in the hole in the earth that is progressively excavated by the disgregating bits, the caisson copies with its outer walls the quadrilateral hole that the disgregating bits make, and the nozzles directed in positions corresponding to the areas of the caisson not reached by the bits complete the disgregation of the soil in said areas not reached by the bits.