Classifications

• • E—FIXED CONSTRUCTIONS
  • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
  • E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
  • E02D5/00—Bulkheads, piles, or other structural elements specially adapted to foundation engineering
  • E02D5/22—Piles
  • E02D5/34—Concrete or concrete-like piles cast in position ; Apparatus for making same
  • E02D5/38—Concrete or concrete-like piles cast in position ; Apparatus for making same making by use of mould-pipes or other moulds
  • E02D5/385—Concrete or concrete-like piles cast in position ; Apparatus for making same making by use of mould-pipes or other moulds with removal of the outer mould-pipes

Definitions

• the present invention relates to the field of drilling techniques in the soil that are performed for the purpose of making foundations and retaining structures in the ground.
• the invention relates more specifically to a method for producing an anchoring in a soil.
• anchoring we mean in particular small diameter drilled piles, also called micropiles, or anchor rods.
• a liquid called a drilling fluid
• a drilling fluid is generally injected in order to cool the cutting tool and to evacuate the cuttings.
• a reinforcement is then placed in the bore before injecting a grout.
• An object of the invention is to provide a method for producing an anchoring in a soil having a better efficiency than the traditional method.
• the invention achieves its object by the fact that the method according to the invention comprises the following steps:
• a drilling tool comprising a drill pipe having an open distal end and means for vibrating the drill pipe;
• an armature is introduced into the drill pipe, and a grout of sealing into the bore via the drill pipe before or after introducing the reinforcement into the drill pipe.
• Sealing grout is any cement-based sealant, slag, or other binder.
• the drill pipe can be removed while leaving the reinforcement in the borehole due to the fact that the distal end of the drill pipe is open.
• the drill pipe thus serves both as means for excavating the ground, but also means for injecting the drilling fluid and the grout into the borehole, in addition to ensuring the maintenance of drilling during the insertion of the drill. frame.
• the vibration frequency is chosen so as to vibrate the drill pipe at its resonant frequency or at least at a frequency close to said resonant frequency.
• the vibration frequency applied to the drill pipe is between 50 Hz and 200 Hz.
• the speed of the implementation of the method according to the invention results in particular from the fact that the drilling is performed by vibrating the drill pipe.
• the vibration which enters the drill pipe and in particular its distal end at the resonant frequency or at least at a frequency close to the resonant frequency, facilitates the penetration of the drill pipe into the ground.
• the drill pipe is also rotated to change the position of cutting teeth disposed at the distal end of the drill pipe.
• the drill pipe serves both as a drill member and as a protective tube for setting up the reinforcement.
• a drilling fluid is injected into the drill pipe during drilling.
• the reinforcement is introduced into the drill pipe before the injection of grouting grout.
• said reinforcement is maintained by appropriate means during the injection of grout.
• An interest is to get an anchor provided with a frame properly centered in the anchorage.
• the reinforcement is introduced into the drill pipe after the injection of grouting grout.
• the armature is held so that its lower end is slightly distant from the bottom of the borehole, which ensures that the distal portion of the frame is completely embedded in the grout.
• the drill pipe is removed after injecting the grout into the borehole.
• the reinforcement is preferably introduced before withdrawal of the drill pipe.
• the drill pipe is removed while injecting the grout into the borehole.
• the sealing slurry is injected while vibrating said drill pipe.
• This vibration can be performed in the context of the first or second embodiment of the invention.
• An interest is to improve the flow and distribution of the grout in the borehole.
• the drill pipe is removed while vibrating and while injecting the grout.
• an interest in vibrating the drill pipe is to allow the withdrawal of the drill pipe without rotation, which has the effect of substantially reducing the risk of circulation of grout between the drill pipe and the drill pipe. ground.
• Another advantage of vibrating the drill pipe is to tighten the ground around the drill pipe, which further reduces the risk of circulation of the grout between the drill pipe and the ground.
• pressurized grout is applied, the drill pipe is removed while injecting pressurized grout through the drill pipe, and while vibrating the drill pipe.
• a pump is preferably used which makes it possible to inject the grout at a pressure of between 0.5 and 5 MPa.
• the pressure injection makes it possible to create a grouting bulb with a diameter substantially greater than the diameter of the borehole, which has the effect of further improving the support.
• the vibration setting advantageously makes it possible to tighten the ground around the drill pipe.
• This tightening has the effect of consolidating the soil and thus allows a pressure injection of the grout in many types of soil without requiring the traditional use of additional accessories type cuffed tubes.
• the direction of drilling is vertical.
• the distal end is formed by the lower end of the drill pipe.
• the direction of drilling is inclined relative to a vertical direction.
• An interest is to be able to achieve inclined anchors.
• An advantageous application lies in the manufacture of inclined anchors.
• the drilling direction is inclined relative to the vertical direction by an angle strictly greater than 90 °.
• An interest is for example to achieve ascending anchorages in a tunnel.
• sealing grout is used as a drilling fluid.
• a vibration target frequency is calculated, and the drill pipe is vibrated at said vibration target frequency during drilling.
• This vibration target frequency which is applied to the drill pipe, is optimally selected to facilitate the drilling operation, particularly in particularly hard soils.
• the computation is carried out starting from a modelization of the phenomena of perforation.
• the calculation uses the length of the drill pipe.
• the vibration target frequency is a function of the length of the drill pipe, while being limited by a value of predetermined maximum frequency, denoted Fmax.
• This predetermined maximum frequency value which preferably corresponds to the maximum frequency that can develop the means for vibrating the drill pipe is preferably between 100 and 160 Hz.
• the calculation uses a constant value corresponding to the speed of propagation of the compression waves in the drill pipe, this speed depending on the constituent material of the drill pipe.
• the reference target frequency is equal to:
• This calculation is performed by a computer having appropriate calculation means.
• drill pipe For deep drilling, the length of the drill pipe is increased during drilling. To do this, tube sections are used that are attached end to end during drilling to increase the length of the borehole. Consequently, within the meaning of the invention, the term “drill pipe” is understood to mean a single drill pipe, a plurality of tubular elements attached end to end, for example by screwing.
• the target frequency of vibration is recalculated with each increase in the length of the drill pipe.
• An interest is to ensure drilling with optimum efficiency over the entire depth of drilling.
• the method is a method of producing a anchor in which the frame is a tie frame.
• the method is a method for producing a micropile, in which the reinforcement is a micropile reinforcement.
• Figure 1A illustrates the drilling step of the method according to the invention
• FIG. 1B illustrates the step of introducing an armature inside the drill pipe
• Figure 1C illustrates the step of injecting the grout into the drill pipe to embed the frame
• Figure 1D illustrates the step of withdrawal of the drill pipe
• FIG. 1E schematically illustrates a micropile obtained at the end of steps 1A to 1D;
• FIG. 2A illustrates an alternative in which sealing grout is injected into the borehole while withdrawing the drill pipe;
• FIG. 2B illustrates the step of introducing the reinforcement into the drilling filled with grout;
• FIG. 3A illustrates another variant of the invention in which seal grout is injected under pressure while raising and vibrating the drill pipe to form a grout bulb;
• FIG. 3B illustrates the introduction of the reinforcement into the grouting bulb
• FIG. 3C illustrates the anchoring obtained at the end of the step of FIG.
• FIG. 4 illustrates variants of the anchoring obtained by implementing the method according to the invention.
• Figure 5 shows schematically the method of optimizing the vibration frequency applied to the drill pipe.
• FIGS. 1A to 1E a first embodiment of the method for producing an anchoring in a soil conforming to FIG. the present invention.
• a micropile M is produced with an armature 30 which is particularly visible in FIG. 1E.
• a drilling tool 10 which comprises a drilling tube 12 consisting of a plurality of tubular elements 12a, 12b, 12c, .... These tubular elements are fixed to each other end to end so as to constitute the drill pipe 12.
• the length L of the drill pipe 12 varies during the drilling. More exactly, during the drilling, a new tubular element is added as the drilling tool penetrates into the ground to those already introduced into the ground, in order to increase the length L of the tube. drilling 12.
• the drill pipe 12 includes a distal end 14 which is open.
• the drilling direction is vertical downward, so that the distal end here corresponds to the lower end of the drill pipe.
• the drill pipe 12 further includes a proximal end 16 which is connected in this example to means 18 for rotating the drill pipe 12 and means 20 for vibrating the drill pipe 12.
• the Means 18 for rotating the drill pipe 12 comprise a hydraulic motor.
• the means 20 for vibrating the drill pipe in this case a vibration generator 20, can generate compressional waves that are transmitted along the drill pipe 12 from the proximal end 16 to the distal end 14 .
• open distal end is meant that the distal end 14 of the drill tube 12 has a through opening which is provided at the center of the distal end 14. As will be explained below, this opening opening has a section of dimension sufficient to be traversed by the frame 30.
• the distal end 14 is completely open, which means in particular that the distal end is in particular devoid of diametral cutting member.
• the distal open end 14 has an annular peripheral edge which is provided with cutting teeth 22.
• cutting teeth By cutting teeth, one means drilling tools in general, such as pimples, knobs, tungsten carbide pellets, etc. These cutting teeth 22 are sized to excavate the soil S during the drilling.
• the length of the drill pipe 12 is referenced L. This length corresponds in fact to the distance between the means 20 for vibrating the drill pipe 12 and the distal end 14 of the drill pipe 12. which essentially corresponds to the distance between the distal and proximal ends of the drill pipe.
• a drilling F is carried out in the soil S by means of the drilling tool 10 by rotating the drill pipe around the vertical axis A by virtue of the rotating drive means 18 and by vibrating it by means 20 to vibrate the drill pipe 12.
• a drilling fluid is injected into the drill pipe so as to evacuate the debris excavated by the cutting teeth 22.
• the distal end 14 comprises perforations 26 at the end of the borehole. through which the drilling fluid flows out of the drill pipe 12 before rising to the surface while flowing between the drill pipe and the wall of the bore F.
• the drilling is performed to bring the distal end of the drill pipe to a predetermined depth H.
• the reinforcement 30 is introduced into the drill pipe.
• the reinforcement could also be introduced into the drill pipe before the drilling fluid is substituted by the grout.
• the armature 30 is a metal bar whose length is slightly greater than the height H of the bore F.
• the armature 30 is lowered to the bottom of the bore while being maintained substantially centered in the drill pipe by holding means 32. As can be seen in FIG. 1C, the armature 30 is held so that its distal end 30a slightly elevated compared to the bottom Fa of drilling F.
• a sealing grout C for example a grout of cement
• the frame is tubular so it can be used advantageously as a pipe and inject the grout from its upper end. The grout is then progressively substituted for the drilling fluid from the lower end by driving it towards the upper end of the borehole.
• the grout is injected into the drill pipe 12 while vibrating the drill pipe through the vibration generator 20.
• the drill pipe 12 After injecting the grout into the bore 12, the drill pipe 12 is removed as shown in FIG. 1D. Alternatively, one can begin to extract the drill pipe before having completely filled the borehole with the grout.
• the micropile M shown in FIG. 1E is then obtained.
• connecting means may be optionally attached to the proximal end 30b of the armature 30 which emerges from the ground.
• FIGS. 2A and 2B show a second embodiment in which the drill pipe 12 is withdrawn while injecting the sealing grout C.
• the withdrawal of the drill pipe is accompanied by a vibrating the drill pipe to prevent the grout from circulating between the drill pipe 12 and the ground S.
• the armature 30 is introduced after removal of the drill pipe.
• the armature could be introduced before removal of the drill pipe.
• FIGS. 3A to 3C disclose a third embodiment of the invention.
• This third mode of implementation differs from that of FIGS. 1A to 1E in that the sealing grout C is pressurized by a pump P in order to be injected under pressure into the drill pipe 12.
• the pressure of the injected grout is of the order of 5 MPa.
• the drill pipe is raised while being vibrated. Vibration has the effect of tightening the ground around the drill pipe 12 and allows to perform a pressure injection, which has the effect of creating a bulb B grout the diameter of which is much greater than that of drilling.
• the bulb B is made over the entire height of the borehole.
• the bulb could be shorter, for example being located at the bottom of the borehole.
• the armature 30 is inserted into the bulb B after the withdrawal of the drill pipe 12.
• the armature 30 could be introduced before the withdrawal of the drill pipe 12.
• FIG. 4 shows another embodiment of anchors obtained by implementing the method according to the invention.
• the anchors made are tie rods referenced Tl and T2, which are obtained by the implementation of the method described above, except that the direction of the drilling Fl for the tie Tl and F2 for the tie T2 , are inclined with respect to a vertical direction.
• the direction of the bore F1 is inclined relative to the vertical direction by an angle strictly greater than 90 °
• the direction of the bore F2 is inclined relative to the vertical direction by an angle of less than 90 °. but strictly greater than 0 °.
• the drill pipe 12 is thus vibrated at the vibration target frequency during the completion of the various drillings F, Fl and F2. It is therefore clear that this vibration target frequency is a vibration frequency that is applied to the drill pipe.
• these vibrations are compressional waves that are transmitted along the drill pipe defining bellies and nodes. These vibration waves bring the drill pipe 12 into resonance, or at least at a frequency close to its resonance frequency, which produces a maximum energy at the distal end 14 carrying the cutting teeth 22, with effect of substantially increasing the drilling efficiency, and therefore the overall efficiency of the method according to the invention.
• the calculation of the vibration target frequency firstly comprises a step S100 during which is manually entered or automatically determines the length L of the drill pipe 12. It is therefore assumed here that the drill pipe is vibrated over its entire length.
• the target frequency of vibration during a step S102 is calculated from the length L of the drill pipe, the speed of propagation of the compression wave in the drill pipe 12
• the drill pipe is made of steel.
• the calculation uses a constant value corresponding to the speed of propagation of the compression waves in the drill pipe, this speed depending on the constituent material of the drill pipe.
• the target frequency of vibrations is recalculated with each increase in the length. of the drill pipe. This keeps an optimal vibration frequency throughout the duration of the drilling.
• the vibration target frequency thus calculated is then displayed as a suggestion to the operator. It may also in another embodiment be sent as a setpoint to the vibration generator 20 during a step S104.
• the reference target frequency is equal to:
• n is an integer greater than or equal to 1 chosen so that
• V is equal to 5000 m / s
• Fmax is equal to 130 Hz
• L the length of the borehole, is equal to the sum of the lengths of the tubular elements 12a, 12b, 12c, .... this example, the elements tubular have the same unit length, namely a length of 3 meters.

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• Engineering & Computer Science (AREA)
• Structural Engineering (AREA)
• Life Sciences & Earth Sciences (AREA)
• General Life Sciences & Earth Sciences (AREA)
• Mining & Mineral Resources (AREA)
• Paleontology (AREA)
• Civil Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Piles And Underground Anchors (AREA)
• Consolidation Of Soil By Introduction Of Solidifying Substances Into Soil (AREA)

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• 2012
  • 2012-09-27 FR FR1259134A patent/FR2995917B1/fr active Active
• 2013
  • 2013-09-26 EP EP13779318.8A patent/EP2900875B8/de active Active
  • 2013-09-26 WO PCT/FR2013/052274 patent/WO2014049277A1/fr active Application Filing
  • 2013-09-26 ES ES13779318T patent/ES2929861T3/es active Active

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