EP1882780A1 - Device for measuring the resistance of a micropile - Google Patents

Abstract

The device has a static/dynamic axial stress exertion unit with a chassis (27) supported at the ground and assembling an actuator e.g. jack. A transmission unit is constituted of a connection unit (2) and transmits axial stress to a head (3) of a helical micropile (4). The connection unit is provided with a reservation presenting a shape of an upper part of the micropile. A limiting unit is constituted of support surfaces and limits the rotation of the micropile. The support surfaces are stopped on other support surfaces of the chassis when the transmission unit transmits the stress.

Description

The invention relates to the technical field of foundation piles.

The term "foundation" refers to all the buried structures that make up the base and the stable base of a building and distribute the loads of this construction on the natural ground or place these loads on the hard ground of sitting.

Depending on the ratio H / B where B is the width of the foundation and H the seat depth, there are: the superficial foundations, for which H / B is less than 6, for example for soles and rafts; deep foundations, for which H / B is greater than 6, eg for bars, wells and piles.

• la nature du matériau constitutif : bois, alliage métallique, béton notamment ;
• le mode d'introduction dans le sol : battage, forage, fonçage, vibro-fonçage, vissage par exemple ;
• le mode de transmission de charge : pieu colonne ne transmettant les charges que par effet de pointe, pieu flottant ne transmettant les charges que par frottement latéral ;
• la taille des pieux : selon le DTU, un micropieu présente un diamètre inférieur à 250 mm.

The piles can be classified according to four criteria:

• the nature of the constituent material: wood, metal alloy, concrete in particular;
• the mode of introduction into the ground: threshing, drilling, sinking, vibro-sinking, screwing for example;
• the mode of load transmission: column pile transmitting the loads only by peak effect, floating pile transmitting the loads only by lateral friction;
• the size of the piles: according to the DTU, a micropile has a diameter less than 250 mm.

• battu enrobé : le pieu est un tube métallique muni d'un sabot débordant, un mortier injecté par l'intérieur du tube, pendant le battage, venant enrober le pieu en remplissant le vide créé par le débord du sabot ;
• à tube battu : le pieu est réalisé à l'aide d'un tube métallique muni d'un bouchon en béton, battu dans le sol, puis rempli de béton ferme pilonné (pieu battu pilonné) ou de béton liquide (pieu battu moulé).

The beaten piles are usually made of steel (profile H with reinforced core or palpieu) or of prefabricated concrete and are put in place by threshing with discharge of the ground. In a variant, the beaten pile is of type:

• batter coated: the pile is a metal tube provided with an overflowing shoe, a mortar injected from the inside of the tube, during threshing, coming to coat the pile by filling the void created by the overhang of the hoof;
• beaten tube: the pile is made using a metal tube with a concrete plug, beaten in the ground, then filled with pounded firm concrete (beaten pile pounded) or liquid concrete (molded beaten pile) .

Dark piles can be made of reinforced concrete, prefabricated, or coffered in progress, or even in steel (H profile with reinforced core or palpieu) and are put in place with discharge of the soil.

The drilled piles are made of reinforced concrete cast in place in a borehole. When the cohesion of the ground allows it, drilling is done without protection (simple bored pile). In other cases, a metal tube protects the bore (cased drilled pile) or a drilling mud is injected (pile drilled with mud). The drilling is done by auger or roto percussion.

• moulé foré : le pieu en béton armé est coulé en place dans un forage réalisé à l'aide d'un outil travaillant par rotation ;
• foré vissé moulé : le pieu est réalisé à l'aide d'un outil à vis, enfoncé par rotation, muni d'un bouchon en fonte qui est perdu et d'un tube permettant le bétonnage au fur et à mesure que l'on retire l'outil.

In a variant, the bored pile is of the type:

• molded drilled: the reinforced concrete pile is cast in place in a borehole made using a tool working by rotation;
• molded screwed drill: the pile is made using a screw tool, driven by rotation, provided with a cast iron plug which is lost and a tube allowing concreting as one remove the tool.

The beaten or drilled piles can be of the high-pressure injected type, an injection system composed of cuffed tubes allowing the injection of a grout into the ground.

• des pieux moulés tubés : pieux en béton armé coulés en place dans un tube coffrant foncé dans le sol ;
• des pieux à vis : pieux préfabriqués munis d'un sabot fileté et enfoncés par rotation.

It is also known in the prior art foundation piles:

• cased molded piles: reinforced concrete piles cast in place in a dark form tube in the ground;
• screw piles: prefabricated piles with a threaded shoe and driven by rotation.

The invention relates more particularly to micropiles of foundation.

The micropile technique was developed in 1952 by the company Fondelile under the direction of the Italian engineer Lizzi. These first piles were drilled and sealed to the ground by a mortar. These products were used in Italy under the name of "root pile". In English, the micropiles are called minipiles, micropiles, root batteries, needle batteries, the terminology is not fixed. They are called mikropfahl, verpresspfahle, wurzelphale in German.

The tables below correspond to the classification of the most common micropiles according to the draft European standard CEN TC 288, from 2002, which became standard NF EN 14199 in September 2005.

• un diamètre du fût inférieur à 300mm pour les pieux forés,
• un diamètre de fût ou une dimension maximale de la section transversale du fût inférieure à 150mm pour les pieux foncés.

Méthodes d'exécution des micropieux forés (selon NF EN 14 199) Méthode de forage Type d'armature Méthode d'injection Type de coulis Options Cage d'armature - remplissage graviaire
-bétonnage -coulis
-mortier
-béton Tubage Injection en une seule passe par un tubage temporaire -coulis
-mortier - remplissage gravitaire
-bétonnage -coulis
-mortier
-béton Tubage Forage rotatif Forage en roto-percussion Benne preneuse trépan ou soupape Élément porteur Injection en une seule passe:
- par un tubage temporaire
- par un élément porteur
- par un tube à manchettes -coulis Injection en plusieurs passes :
- par un tube à manchettes
- par un tube équipé de valves spéciales
- par des tubes « post injection » - coulis Base élargie Injection pendant le forage -coulis Injection répétitive par l'élément porteur Tubage permanent (avec ou sans cage d'amature -remplissage gravitaire
-bétonnage -coulis
-mortier
-béton Base élargie Forage à la tanière creuse continue Cage d'armature ou Elément porteur Bétonnage par la tige creuse. de la tarière -coulis
-mortier
-béton Méthodes d'exécution des micropieux foncés (selon NF EN 14 199) Type de micropieux Matériaux et tubage Section et armature Options et injection A2.1-préfabriqué Béton armé Acier Fonte Pleine Injection autour du fût Tube ouvert injection autour du fût Tube fermé Remplissage avec du coulis du mortier ou du béton avec ou sans injection autourdu fût Profilés injection autour du fût A.22 - Moulé en phase Tubage temporaire Cage d'armature Remplissage gravitaire Injection en une seule passe par un tubage Élément porteur Remplissage gravitaire
Bétonnage Injection en une seule passe:
-par un tubage
-par un élément porteur
-par un tube à manchettes Injection en plusieurs passes :
-par un tube à manchettes
-par un tube équipé de valves spéciales
-par des tubes «post injection» Tubage permanent Cage d'armature Bétonnage à sec, avec ou sans élargissement de la base According to this European standard, a micropile is a pile having:

• a bole diameter of less than 300mm for bored piles,
• a bole diameter or a maximum dimension of the barrel cross-section less than 150mm for dark piles.

<b><u> Methods of execution of micropiles drilled (according to NF EN 14 199) </ u></b> Drilling method Reinforcement type Injection method Type of grout options Reinforcing cage - gravity filling
-bétonnage -coulis
-mortar
-concrete tubing One-pass injection with temporary casing -coulis
-mortar - gravity filling
-bétonnage -coulis
-mortar
-concrete tubing Rotary Drilling Rotor Drilling Bucket Bucket or Valve Carrying element Injection in one pass:
- by temporary casing
- by a carrier element
- by a tube with cuffs -coulis Injection in several passes:
- by a tube with cuffs
- by a tube equipped with special valves
- by "post injection" tubes - grout Extended base Injection during drilling -coulis Repetitive injection by the carrier element Permanent tubing (with or without amature cage -Fast filling
-bétonnage -coulis
-mortar
-concrete Extended base Drilling at the continuous hollow lair Reinforcing cage or Supporting element Concreting by the hollow rod. the auger -coulis
-mortar
-concrete Type of micropiles Materials and casing Section and frame Options and injection A2.1-Prefabricated Reinforced concrete Cast Iron Full Injection around the barrel Open tube injection around the barrel Closed tube Filling with grout mortar or concrete with or without injection around the barrel profiles injection around the barrel A.22 - Molded in phase Temporary tubing Reinforcing cage Gravity filling Injection in a single pass through a casing Carrying element Gravity filling
concreting Injection in one pass:
-by a casing
by a carrier element
-by a tube with cuffs Injection in several passes:
-by a tube with cuffs
-by a tube equipped with special valves
-by "post injection" tubes Permanent tubing Reinforcing cage Dry concreting, with or without expansion of the base

The invention relates more particularly to micropiles of foundation. The terms micropile or pile-root conventionally designate piles of modest cross-section, typically of diameter less than 250 mm, set up with tools of small, light and manageable dimensions, in particular for underpinning.

Due to their small diameter, the micropiles do not work in a point, their lift depends essentially on the lateral friction.

• type I : pieu foré tubé de diamètre inférieur à 250 mm. Le forage est équipé ou non d'armatures et rempli d'un mortier de ciment au moyen d'un tube plongeur. Le tubage est récupéré en l'obturant en tête et en le mettant sous pression au dessus du mortier ;
• type II : pieu foré, de diamètre inférieur à 250 mm, avec injection gravitaire sans pression. Le forage est équipé d'une armature et rempli d'un coulis ou de mortier de scellement, par gravité ou sous une très faible pression, au moyen d'un tube plongeur. Lorsque la nature du sol le permet, le forage peut être remplacé par le lançage, le battage ou le fonçage ;
• type III : pieu foré, de diamètre inférieur à 250mm, avec injection globale unitaire sous pression IGU. Le forage est équipé d'armatures et d'un système d'injection qui est un tube à manchettes mis en place dans un coulis de gaine. Si l'armature est un tube métallique, ce tube peut être équipé de manchettes et tenir lieu de système d'injection. Cette injection est réalisée en tête, de manière globale et unitaire, à une pression supérieure ou égale à 1 MPa. Lorsque la nature du sol le permet, le forage peut être remplacé par le lançage, le battage ou le fonçage ;
• type IV : pieu foré, de diamètre inférieur à 250mm, avec injection répétitive et sélective sous pression IRS. Le forage est équipé d'armatures et d'un système d'injection qui est un tube à manchettes mis en place dans un coulis de gaine. Si l'armature est un tube métallique, ce tube peut être équipé de manchettes et tenir lieu de système d'injection. Cette injection est réalisée à l'obturateur simple ou double d'un coulis ou mortier de scellement à une pression d'injection supérieure ou égale à 1 MPa.

Conventional micropiles are of four different types (DTU 13-2, 1978, modified by additive of 1991 and included in the 62-Title V LCPC 1993):

• type I: cased drilled pile with a diameter of less than 250 mm. The drilling is equipped or not with reinforcement and filled with a cement mortar by means of a dip tube. The casing is recovered by closing it at the top and putting it under pressure above the mortar;
• Type II: Drilled pile, diameter less than 250 mm, with gravity injection without pressure. The drill is equipped with a frame and filled with a grout or mortar, by gravity or under very low pressure, by means of a dip tube. Where the nature of the soil so permits, drilling may be replaced by jetting, threshing or sinking;
• Type III: Drilled pile, diameter less than 250mm, with unit injection under IGU. The borehole is equipped with reinforcement and an injection system which is a tube with sleeves placed in a sheath grout. If the frame is a metal tube, this tube can be equipped with cuffs and take the place of injection system. This injection is carried out at the top, globally and unitarily, at a pressure greater than or equal to 1 MPa. Where the nature of the soil so permits, drilling may be replaced by jetting, threshing or sinking;
• Type IV: Drilled pile, diameter less than 250mm, with repetitive and selective injection under IRS pressure. The borehole is equipped with reinforcement and an injection system which is a tube with sleeves placed in a sheath grout. If the frame is a metal tube, this tube can be equipped with cuffs and take the place of injection system. This injection is performed at the single or double shutter of a grout or mortar at an injection pressure greater than or equal to 1 MPa.

• stabiliser les fondations existantes qui tassent, par exemple sur des pavillons individuels après sécheresse des sols, inondations ou malfaçons ;
• renforcer ces fondations existantes qui doivent reprendre des charges supplémentaires ;
• supporter des charges de structure sur des sites où les accès sont exigus (réhabilitation) ;
• réaliser des fondations dans des terrains durs, traverser d'anciennes maçonneries sans trépanage ni vibrations excessives entraînant des endommagements pour les ouvrages existants.

Micropiles are used to:

• stabilize existing foundations that pile up, for example on individual pavilions after drought, flooding or poor workmanship;
• strengthen these existing foundations, which must take on additional burdens;
• support structural loads on sites where access is limited (rehabilitation);
• build foundations in hard ground, cross old masonry without trepanning or excessive vibrations resulting in damage to existing structures.

The micropiles are conventionally bonded to the structure either by sealing with anti-shrink mortar, in the existing foundations, or by a distribution plate embedded in a reinforced concrete header.

Drilled micropiles are quite commonly used for undercuts in a small space, in the case of individual habitats in particular. Micropiles are also used in groups (set of vertical micropiles) or in networks (set of vertical and inclined micropiles) for soil reinforcement.

An example of a particularly efficient micropile is described in the document EP 1 441 076 in the name of the plaintiff. This micropile driving the soil to its establishment is of the type screwed self-drilling and injectable. It has high pull-out resistance, as well as high compressive strength and buckling.

The Applicant has developed micropiles put in place by embedding cast aluminum elements of about a meter in length, the assembly of these elements being carried out using a stud provided with a particular thread ensuring the alignment of the elements of the micropile. The geometry of the micropiles of the plaintiff is such that they screw themselves in the ground, under the effect of a hammer, without vibration, and this by compressing the surrounding ground. The massive axial core micropiles of the plaintiff gives them a high resistance to buckling.

Other examples of micropiles are illustrated in the documents EP-0954645 or US 4650372 .

We can also refer to the documents SU-1035133 ; EP-0246589 ; EP-0574057 ; EN-718309 ; EN-843499 ; FR-1027187 ; FR-1050555 ; FR-1177711 ; FR-2468696 ; FR-2600686 ; US 6012874 ; WO 93/16236 .

The standard NF EN 14 199 defines several loading tests for micropiles: static loading test, at speed constant depression or palliation; dynamic loading test. As indicated in standard NF EN 14199, micropiles whose supporting elements transmit to the field a compression force by lateral friction can be the subject of a tensile test.

The loading tests on the micropiles are most often difficult to carry out due to limited access. In particular, it is common for the micropile to be placed near a wall (rehabilitation of historic monuments, installation in the living quarters of an individual pavilion for example).

The aim of the invention is to provide tools for controlling the tensile or compressive strength of micropiles which take into account these difficulties particular to this field of activity.

• des premiers moyens aptes à exercer une contrainte axiale statique ou dynamique, ces moyens comprenant un actionneur tel que par exemple un vérin, ainsi qu'un châssis d'appui au sol et de montage de l'actionneur ;
• des deuxièmes moyens aptes à transmettre ladite contrainte axiale à la tête du micropieu hélicoïdal, ces moyens comprenant un organe de liaison pourvu d'une réservation en contre empreinte, cette réservation ayant la forme de la partie supérieure du micropieu ;
• des troisièmes moyens aptes à limiter la course de rotation du micropieu hélicoïdal autour de son axe d'élancement, ces troisièmes moyens comprenant des premières surfaces d'appui, le châssis comprenant des secondes surfaces d'appui contre lesquelles viennent buter les premières surfaces d'appui lorsque les deuxièmes moyens transmettent ladite contrainte axiale à la tête du micropieu hélicoïdal.

For these purposes, the invention relates, in a first aspect, to a device for controlling the resistance of a helical micropower, this installation comprising:

• first means capable of exerting static axial or dynamic stress, these means comprising an actuator such as for example a jack, as well as a chassis for supporting the ground and mounting the actuator;
• second means capable of transmitting said axial stress to the head of the helical micropile, these means comprising a connecting member provided with a reservation in counterprint, this reservation having the shape of the upper part of the micropile;
• third means adapted to limit the rotational stroke of the helical micropile about its axis of slenderness, these third means comprising first bearing surfaces, the frame comprising second bearing surfaces against which abut the first surfaces of support when the second means transmit said axial stress to the head of the helical micropile.

The installation has, in various embodiments, the following characters, if necessary combined.

The third means comprise a transverse plate provided with an annular groove in which at least one pin is slidably mounted and rotatable about its axis of slenderness, this plate being provided with means of assembly to the actuator and means for assembly to the connecting member, said pin being provided with a hole transverse through passage of a removable bar, this removable bar forming the first bearing surfaces.

It is thus possible to control the resistance of piles of different diameters and shapes. The adaptation of the installation to the type of pile is made by the choice of a connecting member provided with adequate reservation. This connecting member is advantageously removably assembled to the plate, for example by screwing. The sliding and rotating mounting of the pins allows easy mounting of the removable bar so that this bar abuts against bearing surfaces of the frame.

The chassis advantageously comprises a lower flange and a substantially parallel upper flange secured by at least two substantially parallel spacers, these spacers forming said second bearing surfaces, the length of said removable bar being greater than the distance between the spacers so that this The bar abuts against the spacers when an axial stress is transmitted to the helical micropile head.

In an advantageous implementation, at least two pins are mounted in the groove of the transverse plate, the frame comprising three spacers substantially equidistant. It is thus possible to limit to a small value the rotational stroke of the micropile head, when applying a traction or compression force on this head. It is also possible to block the rotation of the micropile head in both directions of rotation.

In one embodiment, the transverse plate comprises a lower disk mounted in abutment and secured to the transverse upper face of the connecting member, an upper inner flange and an upper outer flange being mounted in abutment and secured to the lower disk, the internal and external flanges delimiting said annular groove.

Each flange is provided with a shoulder, so that the annular groove has an opening of radial width less than the radial width of its base, the pins being provided with a cylindrical base portion of equal diameter, with the functional clearance, to the radial width of the base of the groove, the pins being also provided with an annular groove of equal diameter, the functional clearance, to the radial width of the opening of the groove.

Advantageously, each peg is provided with at least two superimposed holes for the passage of locking bar in rotation.

• la figure 1 est une vue en perspective d'un dispositif de contrôle de micropieu selon un mode de réalisation de l'invention ;
• la figure 2 est une vue de dessus d'un plateau anti-rotation ;
• la figure 3 est une vue en coupe longitudinale selon le plan III-III de la figure 2, de l'ensemble cloche/disque anti-rotation du dispositif représenté en figure 1 ;
• la figure 4 est une vue en perspective de l'ensemble représenté en figure 3, selon un premier angle de vue ;
• la figure 5 est une vue en perspective de l'ensemble représenté en figure 3, selon un deuxième angle de vue ;
• la figure 6 est une vue en perspective d'un pion ;
• la figure 7 est une vue latérale du pion représenté en figure 6.

Other objects and advantages of the invention will become apparent from the following description of embodiments, which description will be made with reference to the accompanying drawings in which:

• Figure 1 is a perspective view of a micropuncture control device according to one embodiment of the invention;
• Figure 2 is a top view of an anti-rotation plate;
• Figure 3 is a longitudinal sectional view along the plane III-III of Figure 2, the bell / anti-rotation disk assembly of the device shown in Figure 1;
• Figure 4 is a perspective view of the assembly shown in Figure 3, at a first angle of view;
• Figure 5 is a perspective view of the assembly shown in Figure 3, according to a second angle of view;
• Figure 6 is a perspective view of a pin;
• Figure 7 is a side view of the pin shown in Figure 6.

The control device 1 comprises a connecting member 2 to a head 3 of micropile 4.

This connecting member 2 is a solid body provided with a reservation 5 against the imprint (or recessed mold) of the head 3 of the micropile 4.

In one embodiment, the connecting member 2, called bell in the terminology of the applicant, is a metal alloy such as steel, for example NCD 16, the reservation 5 being obtained by electroerosion. In a particular embodiment, the connecting member 2 is molded cast aluminum and the reservation 5 is derived from the molding.

The connecting member 2 comprises a transverse upper face 6 on which opens a plurality of threaded holes 7. In the embodiment shown, the threaded holes 7 extend over substantially less than half the height of the connecting member 2 The tapped holes 7 are advantageously identical and equidistant, their axes being placed at a distance r7 from the axis of slenderness 8 of the micropile 4.

The micropile 4 has a helical head 3, adapted and shaped to be housed, to the functional clearance, in the reservation 5 of the connecting member 2.

A lower disc 9 is mounted in support and secured to the transverse upper face 6 of the connecting member 2.

An upper inner flange 10 and an upper outer flange 11 are mounted in abutment and secured to the top of the lower disc 9.

The lower disc 9, the upper inner flange 10 and the upper outer flange 11 extend substantially transversely with respect to the axis 8 of slenderness of the micropile 4.

The upper inner flange 10 and the upper outer flange 11 have substantially the same thickness and are substantially coplanar.

The lower disc 9 is of substantially constant thickness and comprises a central axial hole 12.

The lower disc 9 also comprises a plurality of substantially identical and equidistant through holes 13 whose axes are placed at a radial distance r13 from the axis of the central hole 12.

The upper inner flange 10 likewise comprises a central axial hole 14 and a plurality of substantially identical and equidistant through holes 15 whose axes are placed at a radial distance r15 from the axis of the central hole 14.

When the upper inner flange 10, the lower disc 9 and the connecting member 2 are in the mounted position, screws pass through the through holes 13, 15 to fit into the threaded holes 7 of the connecting member 2, the central holes 12, 14 then being arranged in alignment. When the head 3 of the micropile 4 is housed in the connecting member 2, the central holes 12, 14 are thus in alignment with the axis of slenderness 8 of the micropile 4.

Fixing the upper outer flange 11 on the lower disc 9 is also provided by screwing, or any other equivalent means.

The upper flanges 10, 11 delimit an annular groove 16 in which pions 17 are housed.

Each flange 10, 11 is provided with a shoulder 18, 19, so that the annular groove 16 has an opening 20 of radial width r20 less than the radial width r21 of its base 21. The pins 17 are provided with a portion cylindrical base 22 of equal diameter, to the functional clearance close to the radial width r21 of the base 21 of the groove 16. The pins 17 are also provided with an annular groove 23 of equal diameter, with the functional clearance, to the radial width r20 of the opening 20 of the throat 16.

The pins 17 are thus slidably movable in the annular groove 16 and are also rotatable on themselves, with respect to their axis of rotation 24.

Each pin 17 has at least one through hole 25, substantially perpendicular to its axis of slenderness 24. In the embodiments shown, each pin 17 is provided with two identical superimposed holes 25a, 25b.

As will appear more completely later, the lower disk 9, the upper inner flange 10 and the upper outer flange 11 constitutes, with the pins 17 and rigid bars 26 passed through the holes 25 of these pins, an antirotation disk. for the micropile.

The control device 1 comprises a frame 27 formed by a base plate 28 and an upper plate 29, these two plates 28, 29 being interconnected by parallel rigid bars 30. The base plate 28 is provided with a hole passage 31 for the head 3 of the micropile 4. The axes of the rigid parallel bars 30 are spaced a sufficient distance for the antirotation disk is housed between these bars 30.

An implementation of the device 1 and an operating mode of this device 1 will now be described.

The micropile 4 is pressed into the ground, using a striking tool, for example a pneumatic hammer or a rotopercussion tool. For the depression of the micropiles, this striking tool is advantageously manual.

At the end of this depression, only the head 3 of the micropile 4 is visible. The operator places the connecting member 2 on this head 3.

Then, the operator fixes on this connecting member 2 the lower disc 9, then the upper inner flange 10. The operator then places the pins 17 against the upper inner flange 10, then attaches the upper outer flange 11 to the disc lower 9, the pins 17 thus being held in the annular groove 16.

Of course, the assembly formed by the lower disk 9, the upper inner flange 10 and the upper outer flange 1 1, the pins 17 may be mounted previously and placed on the connecting member 2. The device for controlling piles thus easily adapts to different geometries of piles, only the connecting member 2 being specific to a pile head geometry, the fastening means of the connecting members 2 can be standardized.

It is also possible for the connecting member 2 and all the parts 9, 10, 11, 17 to be previously mounted and then placed on the head 3 of the micropile 4. This is for example the case when a type micropile is frequently the object of control, eg peel test.

The operator places the base plate 28 and the rigid bars 30 and the upper plate 29. In one implementation, the frame 27 is pre-assembled, the antirotation disk being placed in this frame.

The operator attaches to the upper inner flange 10 an axis 32, this axis 32 passing through the upper plate 29 of the frame 27 and being connected to a stressing means, for example a hydraulic cylinder.

Then the operator moves the pins 17 in the groove 16 so as to accommodate bars 26 in the holes 25 of these pins 17, these horizontal bars 26 bearing against the vertical rigid bars 30 of the frame 27.

Thus, when a tensile or compressive force is applied on the axis 32, this force is transmitted to the micropile head 4, a rotation of the micropile 4 being inhibited by the support of the horizontal rigid bars 26 against the vertical bars 30 of the frame 27.

The device according to the invention has many advantages. In particular, the pins 17 being slidably and rotationally movable on themselves in the groove 16, it is always possible to find an arrangement of these pins 17 for placing a horizontal bar 26 bearing on the frame 27, and this same when the pile is placed in the vicinity of a wall.

The operator can perform all operations facing the device and does not work blind.

The establishment of two horizontal bars makes it possible to block the rotation of the micropile in the two possible directions of rotation. It is thus possible to carry out static or dynamic tests of helical piles as well in traction as in compression.

When, as shown, the pins are provided with two holes 25a, 25b superimposed, it is possible to mount two bars per pin, for example superimposed.

Nomenclature

1

Control device

2

Liaison body

3

Micropile head

4

micropieu

5

Booking of the liaison body

6

Upper transverse face

7

Tapped holes of the connecting member

8

Slenderness axis of the micropile

9

Lower disk

10

Upper internal flange

11

Upper outer flange

12

Central hole of the lower disk

13

Through hole of the lower disk

14

Central hole of the upper internal flange

15

Through-hole of the upper inner flange

16

Ring groove

17

pawn

18

Shoulder of the upper internal flange

19

Shoulder of the upper outer flange

20

Opening of the annular groove

21

Base of the annular groove

22

Cylindrical base of the pieces

23

Annular Throat of the Pieces

24

Panning axis of the pawns

25

Hole crossing pawns

26

Removable bar

27

Frame

28

Base plate of the chassis

29

Upper plate of the chassis

30

spacers

31

Micropile hole

32

Axis of stressing by the actuator

Claims (7)

Device for monitoring the resistance of a helical micropower, this installation comprising: first means able to exert a static or dynamic axial stress, these means comprising an actuator such as for example a jack, as well as a chassis for supporting the ground and mounting the actuator; second means capable of transmitting said axial stress to the head of the helical micropile, these means comprising a connecting member (2) provided with a reservation (5) in counterprint, this reservation having the shape of the upper part (3); ) of the micropile (4); third means capable of limiting the rotational movement of the helical micropile around its axis of slenderness, these third means comprising first bearing surfaces, the frame comprising second bearing surfaces against which the abutments abut first bearing surfaces when the second means transmit said axial stress to the head (3) of the helical micropile (4). Installation according to claim 1, characterized in that the third means comprise a transverse plate provided with an annular groove (16) in which at least one pin (17) is slidably mounted and rotating about its axis of slenderness (24) , this plate being provided with means of assembly to the actuator and means of assembly to the connecting member (2), said pin (17) being provided with a transverse through hole (25) of passage of a removable bar (26), this removable bar (26) forming the first bearing surfaces. Installation according to claim 2, characterized in that the frame comprises a lower flange (28) and an upper flange (29) substantially parallel secured by at least two spacers (30) substantially parallel, these spacers (30) forming said second surfaces of support, the length of said removable bar (26) being greater than the distance between the spacers (30) so that this bar (26) abuts against the spacers (30), when an axial stress is transmitted to the head (3) of the helical micropile. Installation according to claim 3, characterized in that at least two pins (17) are mounted in the groove (16) of the transverse plate, the frame comprising three spacers (30) substantially equidistant. Installation according to any one of claims 2 to 4, characterized in that the transverse plate comprises a lower disk (9) mounted in abutment and secured to the transverse upper face (6) of the connecting member (2), a upper inner flange (10) and an upper outer flange (11) being mounted in abutment and secured to the lower disc (9), the inner and outer flanges (10, 11) defining said annular groove (16). Installation according to claim 5, characterized in that each flange (10, 11) is provided with a shoulder (18, 19), so that the annular groove (16) has an opening (20) of radial width (r20) less than the radial width (r21) of its base (21), the pins (17) being provided with a cylindrical base portion (22) of equal diameter, within the functional clearance, to the radial width (r21) of the base (21) of the groove (16), the pins (17) also being provided with an annular groove (23) of equal diameter, with the functional clearance close to the radial width (r20) of the opening (20) of the throat (16). Installation according to any one of claims 2 to 6, characterized in that each pin is provided with at least two superimposed holes (25a, 25b).

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