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
  • E02D5/74—Means for anchoring structural elements or bulkheads
• • 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
  • E02D5/74—Means for anchoring structural elements or bulkheads
  • E02D5/80—Ground anchors
  • E02D5/808—Ground anchors anchored by using exclusively a bonding material
• • E—FIXED CONSTRUCTIONS
  • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
  • E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
  • E02D7/00—Methods or apparatus for placing sheet pile bulkheads, piles, mouldpipes, or other moulds
  • E02D7/18—Placing by vibrating

Definitions

• the present invention relates to the field of ground drilling techniques which are carried out for the purpose of improving the characteristics of the soil and of making foundations and retaining structures in the soil.
• the invention more specifically relates to a method of placing and sealing a tubular element in a soil located behind a screen.
• screen also called retaining screen, is meant in particular, but not exclusively, the concrete walls and in particular the diaphragm walls.
• Such a tubular element can be used to inject fluid into the soil to improve its physical characteristics.
• the tubular element may also constitute a structural element for making a anchor.
• the invention will find particular application in the case where the soil behind the screen is disposed below a water load, such as a water table.
• a water load such as a water table.
• the soil is saturated with water having a very high pressure, which can in some cases go up to 10 MPa.
• a tubular element for example a tie rod
• the drilling and the establishment of a tubular element, for example a tie rod, under a sheet are operations that are difficult to execute, particularly because of the large value of the ground water pressure.
• An object of the present invention is first of all to provide a method of setting up and sealing a tubular element in a soil under water load located behind a retaining wall.
• the invention achieves its object by the fact that the method according to the invention comprises the following steps:
• a sealing device comprising a drill pipe having a distal end carrying a detachable cutting tool of the drill pipe;
• sealing device is secured to the retaining screen; introducing the drilling device into the sealing device secured to the retaining screen;
• drilling is carried out in the ground by means of the drilling device by vibrating the drill pipe, the drill pipe being brought to a determined depth;
• a grout is injected into the borehole to seal the tubular element in the soil.
• Sealing grout is any sealant based on cement, slag or any other binder.
• distal end means the end of the drill pipe that is intended to be at the bottom of the borehole
• proximal end means the end of the drill pipe which is opposite the end. distal, and which is on the surface out of the borehole.
• the sealing device used in the implementation of the method is well known elsewhere. It may in particular be the device marketed by the French company TEC SYSTEM under the name "SAS BOP”.
• the sealing device makes it possible to seal against the water contained in the soil behind the screen, the pressure of which can be up to 10 MPa.
• the sealing device makes it possible to seal either by functioning as a valve when no member passes through the sealing device, or by making a sealed contact with the drill pipe or the tubular element passing through the sealing device. sealing device. It is therefore understood that the sealing device prevents the ground water from gushing into the working area in which the operators are.
• the sealing device is secured to the screen after pre-drilling the screen all or part of its thickness.
• the pre-perforation of the screen will be finalized after the positioning of the sealing device.
• the securing of the sealing device consists of fixing by appropriate means, by example of the screws, the sealing device on the screen.
• the fastening could be achieved by firmly holding the sealing device against the screen.
• the screen extends vertically and the drilling direction is inclined relative to the vertical.
• a tubular element is obtained embedded in the grout. It is also understood that the cutting tool, which is not raised to the surface, is found embedded in the grout, preferably while remaining attached to the tubular element.
• the grout is injected into the drill pipe.
• the drill pipe is removed while leaving the tubular element and the cutting tool in the borehole, thanks to the fact that the drill pipe is detached from the cutting tool.
• the drilling device thus serves both as means for excavating the ground, but also means for injecting the grout into the borehole, in addition to keeping the bore open during the insertion of the tubular element.
• the vibration frequency is chosen so as to vibrate the cutting tool 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 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 brings the cutting tool into resonance, or at least at a frequency close to the resonant frequency, has the effect of facilitating the penetration of the drill pipe into the ground.
• the drill pipe is also rotated to modify the position of the teeth of the cutting tool.
• a drilling fluid is injected into the drill pipe, the drilling fluid flowing via the cutting tool, and cuttings of the borehole being evacuated via the sealing device.
• the sealing device comprises for this purpose a discharge pipe for the discharge of cuttings drilling.
• the cutting tool is preferably provided with orifices permitting the flow of the drilling fluid.
• the cutting tool is detached from the drill pipe by pushing the cutting tool with the tubular element while maintaining the drill pipe.
• the drilling device comprises connecting means for detachably securing the cutting tool and the drill pipe.
• the tubular element is secured to the detachable cutting tool before pushing the cutting tool with the tubular element.
• This fixing is preferably carried out by screwing the tubular element to the cutting tool. It could however be a fitting by interlocking.
• An advantage of the fastening by screwing is that the operator can feel if the fixation has correctly occurred.
• the grout is injected into the borehole while raising the drill pipe.
• the sealing slurry which flows into the bore, coats the tubular element over at least a portion of its height, whereby the tubular element is sealed in the soil.
• the drill pipe is vibrated during the injection of the grout.
• An interest is to improve the flow and distribution of the grout in the borehole.
• the drill pipe is raised while vibrating said drill pipe. This lift may or may not be accompanied by the injection of 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 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.
• the sealing grout is injected into the tubular element via its proximal end, and flows at the bottom of the borehole via the cutting tool. It is therefore understood that the tubular element serves to bring the grout to the bottom of the borehole, the sealing grout flowing through the orifices in the cutting tool. In this case, it is understood that the sealing slurry flows from the distal end of the borehole and rises towards the proximal end of said borehole.
• the grout is injected between the tubular member and the drill pipe.
• the sealing slurry flows into the borehole through the distal end of the drill pipe. Since the drill pipe is progressively extracted, the injection between the drill pipe and the tubular element makes it possible to perform an injection according to the height of the borehole during the raising of the drill pipe, and not only since the distal end of the borehole.
• the sealing grout is put under pressure, the drill pipe is raised while injecting the pressurized grout into the bore, and while vibrating the drill pipe.
• a pump is preferably used which makes it possible to inject the grout at a pressure of between 0.1 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 bulb may extend over all or part of the height of the borehole. Of preferably, the bulb extends from the bottom of the borehole to the middle of the borehole.
• 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 makes it possible to perform a pressure injection of the grout in many types of soil.
• the sealing device at the drilling head it is possible to perform the injection under high pressure, for example at a pressure of between 0.5 and 5 MPa.
• predefined amounts of grout are injected into predefined soil slices, depending on the initial characteristics of the soil and the improvement objective.
• 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 tie rods, for example to ensure the stability of a diaphragm wall during a terracing operation.
• 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 bounded by a predetermined maximum frequency value, 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 drilling tube, this speed depending on the constituent material of the drill pipe.
• the reference target frequency is equal to:
• n is an integer greater than or equal to 1 chosen so that
• This calculation is performed by a computer having appropriate calculation means.
• tube sections are used that are attached end to end during drilling to increase the length of the borehole.
• 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 invention furthermore relates to a method for producing a tie rod in which the steps of the method according to the invention are implemented and then cables are sealed in the tubular element placed in the borehole.
• the invention further relates to an installation for carrying out the method of placing and sealing a tubular element in a floor behind a screen according to the invention, comprising:
• a drilling device which comprises a drill pipe having a distal end carrying a detachable cutting tool of the drill pipe, a sealing device configured to be secured to a retaining screen and leaktight through the tubular element or the drill pipe;
• the means for detaching the cutting tool from the drill pipe comprise in particular the tubular element.
• the cutting tool comprises a fixing sleeve having a diameter smaller than the diameter of the drill pipe, said sleeve being configured to be attached to a distal end of the tubular member.
• the sleeve has a thread or a thread configured to cooperate with a thread or a complementary thread located at the distal end of the tubular element.
• the cutting tool comprises a channel connecting the sleeve to one end of the cutting tool provided with a cutting edge and injection orifices, said channel making it possible to feed the injection orifices with fluid, and the cutting tool further comprises a non-return valve arranged to close the channel when no fluid flows from the sleeve to the injection ports.
• the non-return valve opens to let the grout (or drilling fluid) pass, the latter flowing in the bore through the injection ports.
• the installation according to the invention comprises releasable holding means for holding together the cutting tool and the drill pipe during drilling.
• these releasable holding means comprise a pin attached to the cutting tool and engaging in a groove or recess formed at the distal end of the drill pipe or a tool holder attached to the distal end of the drill pipe.
• the pin is configured to disengage groove when an axial force of predetermined intensity is applied to the cutting tool.
• the installation comprises an annular sealing member for sealing between the drill pipe and the cutting tool.
• the sealing member is integral with the drill pipe and bears against the sleeve or the body connected to the sleeve.
• the sealing member is configured to pass a fluid only in the case where said fluid flows axially towards the distal end of the drill pipe.
• This fluid can be water, grout, or any other type of fluid. It is thus understood that the sealing member is configured to prevent the fluid from returning to the proximal end of the drill pipe by circulating between the sleeve and the drill pipe.
• the sealing member is also configured to seal between the drill pipe and the tubular element after attachment of the tubular member to the sleeve and detachment of the cutting tool.
• the drilling installation further comprises a damper disposed between the sealing device and the drill pipe in order to prevent the transmission of the vibrations of the drill pipe towards the sealing device.
• a damper disposed between the sealing device and the drill pipe in order to prevent the transmission of the vibrations of the drill pipe towards the sealing device.
• FIG. 1 illustrates the establishment of a sealing device of the installation according to the invention in a reservation made in a retaining screen
• FIG. 3 illustrates the drilling step in the soil after introduction of the drilling device in the sealing device
• FIG. 4 illustrates the introduction of the tubular element into the drill pipe and its attachment to the screw cutting tool
• FIG. 5 illustrates the step during which the cutting tool is detached from the drill pipe
• FIG. 8 is a detailed view of the distal end of the drilling device
• FIG. 9 is a front view of the cutting tool
• FIG. 10 is a longitudinal sectional view of the distal end of the drilling device showing the cutting tool connected to the drill pipe;
• FIG. 11 is a longitudinal sectional view of the distal end of the drilling device showing the cutting tool detached from the drill pipe;
• FIG. 12 schematizes the method for optimizing the vibration frequency applied to the drill pipe. Detailed description of the invention
• the screen E is a retaining screen consisting of a vertical molded wall.
• One of the faces El of the screen E is disengaged while the opposite face E2 is located on the side of the soil layer S.
• the soil layer S which is supported by the screen E is, in this example, disposed below a water load, such as a water table. Since the method of manufacturing the screen E is well known, it will not be described in detail here.
• the purpose of the method according to the invention is to set up and seal a tubular element 90 in the soil S located behind the screen E.
• This tubular element may be for example a reinforcement or a perforated tube intended for making injections
• the method according to the invention can be implemented in order to manufacture a anchor or in order to carry out injections into the ground S.
• a sealing device 10 which is secured to the screen.
• the screen E is drilled along part of its thickness in order to make a reservation R in the screen E.
• the drilling axis A is inclined at an angle relative to the horizontal.
• the drill axis A is also inclined with respect to the vertical.
• the sealing device 10 comprises a front tubular end 12 which is introduced into the reservation R. It is found that the diameter of the tubular end 12 is substantially equal to the diameter of the reservation R. The reservation is then drilled according to any the thickness of the screen.
• the reservation R sets up the reservation R at the time of the execution of the screen E.
• the reservation R is in the form of a tube and a plate to allow the sealing device 10 to be secured.
• the reservation R is integral with an armature cage (not shown here) constituting the skeleton of the retaining shield E.
• the sealing device 10 further comprises a chimney chamber 14 which is connected to the tubular end 12; this chimney chamber has a discharge chimney 16 for evacuating the excavation cuttings.
• the sealing device 10 further comprises a valve 18 connected to the chimney chamber 14 and a first half-chamber 20 connected to the valve 18.
• the valve 18 is a pinch valve with elastic deformation, well known elsewhere. Its function is to seal by virtue of the fact that the sleeve engages a tubular member passing through the valve 18. It also makes it possible to close the sealing device when no member passes through the sealing device.
• the sealing device 10 is part of an installation 100 according to the invention which further comprises a drilling device 30.
• This drilling device 30 comprises a drilling tube 32 having a distal end 34 which carries a cutting tool 36 According to the invention, this cutting tool 36 is detachable from the drill pipe 32.
• the drill pipe 32 consists of a string of rods that are attached end to end to increase the length of the drill pipe during drilling.
• the drilling device 30 is introduced into the sealing device 10.
• the distal end of the device of the drill pipe is equipped in this example with a stuffing box 38, a second half-chamber 40 which surrounds the drill pipe 32.
• the second half-chamber 40 is assembled with the first half-chamber 20 of the sealing device 10.
• the first half-chamber 20 and the second half-chamber 40 are fixed to one another while enclosing a thick rubber ring 42, so that the assembly consisting of the first half-chamber 20, the second half-chamber 40 and the rubber ring 42 constitutes a vibration damper 44.
• This damper 44 which is disposed between the sealing device 10 and the drill pipe 32, has the role of preventing the transmission of vibrations from the drill pipe to the sealing device.
• the sealing device and in particular the valve 18, makes it possible to prevent the ground water from spouting on the working area of the operators, this zone being separated from the ground S by the screen E .
• the installation 100 furthermore comprises means 50 for vibrating the drill pipe 32.
• the means 50 for vibrating the drill pipe 32 in this case a vibration generator 50, make it possible to generate compressional waves which transmit along the drill pipe 32 to its distal end 34 and to the cutting tool 36.
• L is the length of the drill pipe 32 between its distal end and the vibration generator 50. The length L of the tube drilling 32 therefore increases during the drilling.
• a drilling F is carried out in the ground S by means of the installation 100 by means of the drilling device 30 of the installation 100 by vibrating the drill pipe 32 by means of the vibration generator 50.
• the drill pipe 32 is also rotated about the drill axis A by means of rotational drive means 52.
• a drilling fluid G is injected into the drill pipe from the proximal end 37 of the drill pipe 32.
• This drilling fluid G flows into the drill pipe 32 to the tool
• the cutting tool 36 is provided with orifices 35 enabling the drilling fluid G to be injected at the bottom of the bore F.
• the drilling fluid G then rises along the borehole, carrying the cuttings, then traverses the borehole.
• the drilling is performed until the drill pipe, and more precisely the cutting tool is brought to a specific depth H shown in Figure 4.
• the determined depth H is the distance between the face E2 of the screen E turned towards the ground S and the bottom Fl of the bore F.
• the detachable cutting tool 36 is initially mounted on a tool holder 37 which is fixed to the distal end 34 of the drill pipe 32.
• the cutting tool 36 further comprises a fixing sleeve 60 which has a diameter smaller than the inside diameter of the drill pipe 32.
• the sleeve 60 is integral with a body 64 in which is formed a channel 62 which extends along the axial direction X of the drill pipe. This channel 62 connects the sleeve 60 to the cutting edge 66 of the cutting tool 36. Consequently, the channel 62 makes it possible to feed the injection orifices 35 with fluid, in particular, but not exclusively, with drilling fluid during the step drilling.
• the cutting tool 36 further comprises a nonreturn valve 68 which is arranged at the downstream end 62a of the channel 62 in order to close off said channel 62 when no fluid is present. flows from the sleeve 60 to the injection ports 35.
• the check valve 68 consists of a part 70 mounted on a spring 72 so that the non-return valve allows to pass a flow that flows to the orifices 35 of the cutter 66, but prevents a flow from flowing through the channel 62 to the sleeve 60. It is therefore understood that the body 64 in which the channel 62 is formed is disposed between the anti-tamper valve. return 68 and the attachment sleeve 60.
• the cutting tool 36 is detachable from the tool holder 37 and thus from the drill pipe 32.
• the cutting tool 36 comprises a pin 74 which extends transversely with respect to the axis of rotation X of the cutting tool so as to be housed in two notches 76 formed in the tool holder 37.
• the pin 74 is dimensioned so that it is mounted tightly in the notches 76 in order to avoid inadvertent detachment of the cutting tool 36 with respect to the tool holder 37.
• the notches 76 open axially towards the end distal 37a of the tool holder 37 which is directed towards the cutter 66. It is therefore understood that an axial thrust on the sleeve 60 directed towards the cutter 66 having an intensity greater than a predetermined threshold makes it possible to disengage the pin 74 from the indentations 76 and thus to detach the cutting tool 36 from the drill pipe 32.
• pin 74 and the notches 76 are releasable holding means for holding together the cutting tool and the drill pipe during drilling.
• the installation 100 comprises a sealing member 80 for providing an axial seal between the drill pipe 32 and the sleeve body 60.
• the device 80 is an annular seal which is integral with the drill pipe 32.
• the sealing member 80 is also integral with the tool holder 37. The sealing member 80 comes therefore bear against the outer surface of the body 64 to seal between the drill pipe 32 and the cutting tool 36.
• the sealing member 80 is configured to pass a fluid only in the case where said fluid flows axially towards the distal end 34 of the drill pipe 32.
• the sealing member 80 passes only the flows directed to the cutter 66. It thus makes it possible to prevent a upward circulation of fluid between the sleeve 60 and the drill pipe 32.
• the sealing member 80 when the cutting tool 36 is attached to the tool holder 37, the sealing member 80 bears against the body 64.
• the sleeve 60 has an outside diameter which is substantially equal to the outside diameter of the body 64, it is understood from FIG. 11 that when the cutting tool 36 is detached from the tool holder 37, the sealing member 80 moves axially and bears against the sleeve in order to maintain the axial sealing between the drill pipe 32 and the sleeve 60.
• a tubular element 90 is introduced into the tube of This tubular element 90 also consists of a plurality of portions of tubes which are attached end to end.
• the tubular element 90 is introduced into the drill pipe 32 until the distal end 90a of the tubular element 90 comes into contact with the end 60a of the sleeve 60.
• the tubular element 90 is then rotated to screw the distal end 90a of the tubular member 90 to the thread 82 of the sleeve 60.
• a thrust is exerted on the tubular member 90 to push the cutting tool 36, causing the cutting tool 36 to detach from the drill pipe 32.
• the drill pipe 32 is held while pushing the tubular member 90 attached to the cutting tool.
• the separation of the cutting tool 36 from the drill pipe 32 is illustrated in FIG. 5.
• grout C for example a grout of cement
• the grout C is injected into the tubular element 90 by its proximal end and flows at the bottom of the bore through the orifices 35 of the cutting tool 36.
• the injection of the sealing slurry C is carried out by raising the drill pipe 32 while vibrating the drill pipe 32.
• the vibrations make it possible to tighten the soil S around the drill pipe which avoids a rising circulation of the grout between the drill pipe 32 and the ground S.
• the vibration frequency of the drill pipe applied during the rise of the drill pipe 32 is of the order of 50 Hz to 130 Hz depending on the length of the drill pipe.
• the grout C is pressurized by a pump, not shown here, before its injection into the tubular element.
• a pump not shown here
• An interest is to be able to form a bulb of grout having a larger diameter.
• the pressurized sealing slurry may reach a pressure of the order of 0.5 to 5 MPa.
• the injection of grout could be achieved by an injection between the element tubular and the drill pipe as soon as the sealing member 80 allows the flow of the grout to the cutting edge 66.
• the vibrations emitted by the vibration generator 50 are transmitted to the drill pipe 32 but not to the sealing device 10 or the screen E.
• the drill pipe 32 is raised again until the distal end of the drill pipe 32 reaches the sealing device 10. The drill pipe 32 is then removed from the device sealing 10.
• the tubular element 90 is then sealed in a bulb B of grout.
• This tubular element 90 can then be used to manufacture a anchor by sealing cables (not shown here) in the tubular element set up and sealed in the borehole.
• the drill pipe 32 is thus vibrated at the vibration target frequency during the drilling. 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 32 into resonance, or at least at a frequency close to its resonant frequency, which produces a maximum energy at the cutting tool 36, with the effect of substantially increase the drilling efficiency, and thus the overall efficiency of the process according to the invention.
• the calculation of the vibration target frequency firstly comprises a step S100 in which the length L of the drill pipe 32 is manually entered or determined automatically. So here assumes that the drill pipe is vibrated along its entire length. Then, from this 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 32
• the drill pipe 32 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 vibration frequency is recalculated at each increase in the length of the tube. drilling. 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 50 during a step S104.
• the reference target frequency is equal to:
• V is equal to 5000 m / s
• Fmax is equal to
• L corresponds to the sum of the lengths of the tubular elements placed end to end.
• the tubular elements have the same unit length, namely a length of 3 meters.
• the following result table is obtained:

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• 2012
  • 2012-11-29 FR FR1261442A patent/FR2998593B1/fr active Active
• 2013
  • 2013-11-20 WO PCT/FR2013/052797 patent/WO2014083263A1/fr active Application Filing
  • 2013-11-20 EP EP13808085.8A patent/EP2925935B1/de active Active
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