Drilling tool for laying a tube in the ground

Abstract

A drilling tool for laying a tube ( 3 ) around a buried elongated element ( 1 ), comprising a drilling head ( 2 ) guided by the buried element ( 1 ), moving under the action of a pressurized fluid, from a first free end ( 14 ) of the buried element towards a second end ( 13 ) of the buried element ( 1 ), and pulling the tube ( 3 ), characterized in that the drilling tool comprises pressurization means ( 4 ) attached to the first end ( 14 ) of the buried element ( 1 ), able to slide into the tube ( 3 ) pulled by the drilling head ( 2 ) and able to create a pushing force on the drilling head ( 2 ) by the pressurization with said pressurized fluid of a pressure chamber ( 42 ) arranged between the drilling head ( 2 ) and the pressurization means ( 4 ).

1 . A drilling tool for laying a tube around a buried elongated element, comprising
 a drilling head guided by the buried element, moving under action of a pressurized fluid, from a first free end of the buried element towards a second end of the buried element, and pulling the tube; and   pressurization means attached to the first end of the buried element, able to slide into the tube pulled by the drilling head and able to create a pushing force on the drilling head by the pressurization with said pressurized fluid of a pressure chamber arranged between the drilling head and the pressurization means.   
     
     
         2 . The drilling tool according to  claim 1 , wherein the drilling head is directly fed with pressurized fluid by the pressure chamber. 
     
     
         3 . The drilling tool according to  claim 1 , further comprising:
 on a front portion, the drilling head comprising a first impact body sliding over a second concentric body,   an oscillating mass activated by means for supplying and channeling the pressurized fluid regularly coming to hit a rear side of said impact body, said drilling head operating like a percussion hammer, the drilling head being arranged and advancing coaxially to the buried elongated element,   wherein the second concentric body comprises sealing fixing means of said tube, and   wherein the pressurization means are a cap with a cylindrical shape, arranged behind the drilling tool and behind the first free end of the elongated element, within the tube during the pulling, said cap being attached to said free end and being provided with sliding sealing means between its perimeter and the internal surface of the tube, said cap comprising attachment means of a feeding pipe with the pressurized fluid, a feeding pipe feeding with said pressurized fluid inside the pressure chamber arranged in the front portion of the tube, between a rear side of the second body and a front side of said cap, the pressure exerted by said pressurized fluid creating the substantially continuous pushing force against the rear side of the second body contributing to the pushing of said drilling head pulling the tube around the elongated element.   
     
     
         4 . The drilling tool according to  claim 3 , wherein the sealing fixing means of the tube on the second concentric body comprise a substantially cylindrical portion of the second concentric body with notches as well as an O-ring seal arranged between said second concentric body and the tube. 
     
     
         5 . The drilling tool according to  claim 4 , wherein the sealing fixing means of the tube on the second concentric body further comprise a pipe clamp arranged on the outside surface of the tube and coming to press said tube against the substantially cylindrical surface of the second concentric body provided with notches. 
     
     
         6 . The drilling tool according to  claim 3 , further comprising filter means for filtering fluid in the pipes of the fluid system. 
     
     
         7 . The drilling tool according to  claim 1 , wherein said substantially continuous pushing force applied to the drilling head is substantially equal to the product of the fluid pressure value in the pressure chamber multiplied by the section of the crown whereof the external diameter equals the internal diameter of the tube and the internal diameter equals the external diameter of the elongated element. 
     
     
         8 . The drilling tool according to  claim 1 , wherein the associated pressurization means comprise a safety means comprising at least two brake linings able, during a rupture of the attachment of the pressurization means to the end of the elongated element, to move radially and to block the pressurization means within the tube, under the action of a conical crown activated by the pressure inside the pressure chamber, a means further being provided to cut the arrival of the pressurized fluid in the pressure chamber. 
     
     
         9 . The drilling tool according to  claim 1 , further comprising a safety disk comprising two semi-tubular portions tightly encircling a portion close to the first rear end of the elongated element and fixed together by screws, said safety disk separating the pressure chamber into two portions of chambers, a fluid communication of small section being provided in the safety disk and connecting the two portions of chambers. 
     
     
         10 . The drilling tool according to  claim 1 , wherein the fluid is air. 
     
     
         11 . The drilling tool according to  claim 1 , wherein the fluid is a liquid. 
     
     
         12 . The drilling tool according to  claim 1 , further comprising a fixing disk attached to the elongated element close to the second free end of said elongated element, a supporting surface of said disk coming to abut against a wall of backfill in order to prevent a retraction movement of the elongated element. 
     
     
         13 . The drilling tool according to  claim 1 , wherein the elongated element is an electric power or telecommunications cable. 
     
     
         14 . The drilling tool according to  claim 1 , wherein the elongated element is a pipe. 
     
     
         15 . A method for laying a tube around a buried elongated element comprising:
 causing the advance of a drilling head by means of a pressurized fluid, from a first free end of the elongated element;   pulling the tube by the drilling head;   creating a pressure chamber between the drilling head and the first free end of the elongated element; and   applying an additional pushing force on the drilling head by pressurizing the pressure chamber.