EP1820904A1 - Foundation pile and method for reinforcing foundations - Google Patents

Abstract

The pile has expansible sheaths (2) covering end and part of the body of the pile, respectively, where the sheaths have the nature to confine a hardening grout (4). The sheaths form a compacting bulb at the end of the pile and make the pile adhere to the ground and the structures surrounding the pile. Injection pipes inject the grout independent of level of body and the end. An armature structure (1) is formed of an armature tube which is pierced at its lower part. An independent claim is also included for a method of anchoring pile in ground and reinforcing foundation.

Description

The invention relates to the field of anchoring piles and / or foundations. Many techniques have been developed in this field to ensure proper anchoring of the piles and / or increase their bearing capacity, including the injection of grout hardening around piles placed in boreholes, the formation of bulbs at the end of the pile. pile (for example by injection of a curing slurry into an expandable envelope), the use of flexible membranes for sheathing a tube in which a hardening grout is injected, etc.
The patent FR 2 601 706 is a general illustration of the implementation of the various techniques envisaged. The document describes several of these alternatives in very distinct embodiments.

Applicants have now found that a particular combination of the stated techniques offers new and useful advantages in the context of specific ground anchor and / or foundation reinforcement applications.

The object of the present invention is to provide a new foundation pile formed of a reinforcing structure and a hardening grout, the end of which is provided with a bulb formed of hardening grout surrounded by an expandable sheath, said pile being provided with at least one expandable sheath wrapping its end and at least one expandable sheath wrapping at least a portion of its body, said sheaths being such as to confine the hardening slurry and respectively forming a compacting bulb from the soil to the end of the pile, and adhering the pile to the ground and / or structures surrounding the pile.

According to a preferred embodiment of the invention, the reinforcing structure is more particularly formed, at least in part, of a reinforcing tube while at least one expandable sheath wraps the end of said armature tube and at least one expandable sheath envelops at least a portion of the body of said armature tube.

According to a preferred characteristic of the invention, the essential aspect of the confinement of the hardening grout results from the mesh of the sheath, chosen as a function of the characteristics of the hardening grout (preferably of the mineral type, micro-crushed, anti-swelling, anti-shrinkage). and hydrophobic).

According to other preferred features of the invention,
the pile reinforcement tube has a diameter of the order of 100 mm (ie a diameter of between about 75 and 200 mm);
the expandable sheath surrounding the body of said reinforcing tube constitutes a textile sleeve having a diameter between 200 and 300 mm; and
the expandable sheath surrounding the end of said reinforcing tube constitutes a textile sleeve having a diameter between 300 and 600 mm, more particularly approximately 500 mm.

In a particular embodiment of the invention, the foundation pile is preferably of the type called "micro-pile", having a length between 1.5 and 10 m and a diameter between 20 and 35 cm approximately.

The present invention also relates to a method of anchoring structures in the soil and / or reinforcing foundations involving the establishment of a pile comprising a reinforcing structure, and the injection of grout hardening at the level of body of the pile and / or in an expandable sheath at the end of said pile, the hardening grout being injected into at least one expandable sheath wrapping a portion of the body of said pile, so as to adhere the sheath (s) expansible to soil and / or structures surrounding the pile, and in at least one expandable sheath wrapping the end of said pile, so as to form a soil compaction bulb at the end of the pile.

According to an additional characteristic of this method, the mesh of the sheaths used is more particularly chosen so that the sheaths allow the confinement of the hardening grout.
The mesh is more particularly chosen according to the characteristics of the hardening grout.

According to another preferred feature of the invention, the hardening grout is preferably independently injected at the pile body and at the end of the pile.
This embodiment of the invention allows the control of the pile abutment by controlling the pressure of the grout at the end of the pile.

The method according to the invention is more particularly used for the anchoring in the ground, the realization of foundations and / or the reinforcement of existing or new structures, by using micro-piles having a length between 1.5 and 10. m and a diameter between 20 and 35 cm.

• minéral : composé essentiellement voire uniquement d'ingrédients de type minéral, tel que ciments, agrégats à base de quartz et/ou de matériaux silicieux, etc.;
• micro broyé : ayant une granulométrie essentiellement inférieure à 0,1 mm
• anti-gonflement : ne subissant pas d'augmentation de volume au moment de la prise, ni de dégagement de vapeur
• anti-retrait : ne subissant pas de diminution de volume (pas de ressuage) au moment de la prise ;
• hydrophobe : ne se mélangeant pas à l'eau après la mise en émulsion (entrainant un refoulement de l'eau après la mise en émulsion).

According to another preferred feature of the invention, the method uses a mineral, micro-milled, anti-swelling, anti-shrinkage and hydrophobic injection type hardening grout.
In the present context, the terms mineral, micro milled, anti-swelling, anti-shrinkage and hydrophobic have more particularly the following meanings:

• mineral : consisting essentially or solely of mineral-type ingredients, such as cements, aggregates based on quartz and / or siliceous materials, etc .;
• milled micro : having a particle size substantially less than 0.1 mm
• anti-swelling : does not undergo an increase in volume at the time of setting, nor release of steam
• anti-shrinkage : not shrinking in volume (no bleeding) at the time of setting;
• hydrophobic : does not mix with water after emulsification (resulting in water backflow after emulsification).

Representative compositions of these properties are in particular compositions used by the company M.TECH under the name 'injection grout CA'.

The pile according to the invention, designated in this context as "horizontal compacting pile" ("PCCH"), is therefore a type of drilled foundation pile of length varying between 1.5 m and 10 m and of diameter that can vary. from 20 to 35 cm, being able to be installed in any type of soil including through a water table, with a simple material and little cumbersome.

The pile is preferably composed of an armature in this case a tube pierced at its lower part, wrapped in one or more expandable geotextile sheaths. Two pipettes are placed in the pile so as to allow independent injection of the body and the tip of the pile at different pressures. These sheaths are sufficiently extensible to allow it to adhere perfectly to the walls of the borehole and to create a bulb at the tip of the pile by compacting the soil.

After installing the pile in a borehole, a hardening grout is injected under pressure, preferably a micro-milled, anti-swelling, anti-shrinkage and hydrophobic mineral grout. The sheaths contain the grout in the tube and around it. This system allows a complete control of the realization of the pile by preventing the grout from spreading in the infractuosities of the ground or being washed by the water contained in the ground.

1. a) l'armature :
   • Un tube en acier inoxydable de diamètre 100 mm est plus couramment utilisé en une ou plusieurs pièces suivant la longueur et les moyens de manutention disponibles ou possibles sur chantier.
   • Le tube comporte trois parties distinctes (pouvant être des éléments différents si celui-ci est composé de plusieurs pièces) :
     • la tête dont la partie supérieure est scellée d'un plaque percée de deux ouvertures par lesquelles pénètrent les pipettes d'injection de la pointe et du corps du pieu ; cette pièce pouvant être aménagée de manière à assurer la liaison avec la structure sus-jacente
     • la pointe ("racine") constituée d'un tube scellé à sa partie inférieure , percé de toutes parts afin de laisser s'échapper le coulis injecté à une pression supérieure par une pipette indépendante pour créer le bulbe
     • le corps constitué d'un ou plusieurs tubes percés de deux trous à leur partie inférieure pour laisser passer le coulis
   • Les tubes sont fixés l'un à l'autre par un système de boulons lors du placement du pieu dans le trou de forage.
   • Le confinement du coulis dans le tube confère au pieu une résistance finale à la flexion très élevée.
   • D'autres formes d'armatures sont envisageables telles des assemblages de barre HR et d'étriers.
2. b) la gaine :
   • La gaine est un manchon en textile de diamètre variant de 200 mm à 300 mm, enveloppant l'armature et fixé au extrémités de chaque pièce composant le tube.
   • Les propriétés du fil utilisé et la densité du tissage assurent le confinement du coulis injecté sous pression à l'intérieur du manchon et de l'armature. L'extensibilité de la gaine assure une adhésion complète du pieu aux parois de forage. Le diamètre de la gaine est fonction de celui du forage.
   • L'extrémité inférieure du pieu est équipée d'une gaine, plus large, de diamètre 500 mm qui permet la constitution d'un bulbe de 600 mm de diamètre.
3. c) le coulis :
   • Le coulis est le mélange fait sur place d'eau claire et d'un mortier minéral micro broyé prêt à l'emploi.
   • Les caractéristiques du coulis se résument de manière suivante :
     • pompable et injectable
     • durcissement en 24 h sans retrait ni gonflement
     • adhérence maximum tant dans le sol que dans les parties de structure traversées
     • non corrosif car ne comprenant pas de chlorures , sulfures ou agrégats métalliques
     • hydrophobe
     • n'absorbe pas l'huile

The three main components of the pile are

1. a) the frame:
   • A stainless steel tube with a diameter of 100 mm is more commonly used in one or more pieces depending on the length and the means of handling available or possible on site.
   • The tube has three distinct parts (which can be different elements if it is composed of several parts):
     • the head whose upper part is sealed with a plate pierced with two openings through which penetrate the injection pipettes of the tip and the body of the pile; this part can be arranged to ensure the connection with the overlying structure
     • the tip ("root") consists of a tube sealed at its lower part, pierced from all sides to let escape the grout injected at a higher pressure by an independent pipette to create the bulb
     • the body consists of one or more tubes pierced with two holes at their lower part to let the grout pass
   • The tubes are attached to each other by a system of bolts during the placement of the pile in the borehole.
   • The confinement of the grout in the tube gives the pile a final resistance to very high bending.
   • Other forms of reinforcement are conceivable such as assemblies of HR bar and stirrups.
2. b) the sheath:
   • The sheath is a textile sleeve of diameter ranging from 200 mm to 300 mm, surrounding the frame and fixed to the ends of each component of the tube.
   • The properties of the yarn used and the density of the weave ensure the confinement of the grout injected under pressure inside the sleeve and the reinforcement. The extensibility of the sheath ensures complete adhesion of the pile to the drilling walls. The diameter of the sheath is a function of that of the borehole.
   • The lower end of the pile is equipped with a sheath, wider, diameter 500 mm which allows the constitution of a 600 mm diameter bulb.
3. c) the grout:
   • Grout is the on-site blend of clean water and a micro-milled mineral mortar ready for use.
   • The characteristics of the grout are summarized as follows:
     • pumpable and injectable
     • curing in 24 hours without shrinkage or swelling
     • maximum adhesion both in the ground and in the structural parts crossed
     • non-corrosive since it does not include chlorides, sulphides or metal aggregates
     • hydrophobic
     • does not absorb oil

The invention can be used in a number of applications, including among others the underpinning of foundations, the anchoring of retaining walls, the foundation of hedge walls and isophonic.

The PCCH according to the invention makes it possible to fetch the resistant layers in order to found the construction thereon but can also be used as a floating pile thanks to the compaction of the soils that entails the injection pressure of the grout and the creation of the bulb at its tip .

The PCCH is applicable practically in all types of terrain including immersed.

The PCCH has a good tensile and flexural strength thanks to its reinforcement and the perfect adhesion between it and the grout. In addition, its bulb gives it resistance to tearing.

Its installation requires only a small equipment and this type of solution is perfect for confined spaces.

The sealing plate of the PCCH head allows the creation of any type of interface with the overlying structure.

• la Figure 1 montre, de manière schématique, un pieu de fondation selon l'invention, et
• la Figure 2 montre, de manière schématique, les stades (1) à (6) de la méthode selon l'invention, pour la mise en ouvre de tels pieux.

Other characteristics, details and particularities of the invention will appear on reading the following description of a specific embodiment, given purely by way of illustration and without limitation, with reference to the appended drawings, in which:

• Figure 1 shows, schematically, a foundation pile according to the invention, and
• Figure 2 shows schematically the steps (1) to (6) of the method according to the invention, for the implementation of such piles.

The pile shown in Figure 1 has three parts separated from each other, namely the "head", the "body", and the "root".

The pile is composed of a reinforcement in this case a tube pierced at its lower part (1), wrapped in one or more expandable geotextile sheaths (2). Two pipettes (3) are placed in the pile so as to allow independent injection of the body and the tip of the pile at different pressures. After having installed it in a borehole, a micro-milled, anti-swelling, anti-shrinkage and hydrophobic mineral grout is injected (4) under pressure. The sheaths contain the grout in the tube and around it. These sheaths are sufficiently extensible to allow it to adhere perfectly to the walls of the borehole and to create a bulb at the tip of the pile by compacting the soil.

The PCCH pile according to the invention has the advantage of being able to be used in any type of soil, to be able to be placed with an inclination varying from 0 ° to 90 ° and to be able to be implemented thanks to a little equipment. bulky and light, so in confined places.

• le forage sera exécuté à l'aide d'une carotteuse munie de couronnes diamant en cas de reprises en sous oeuvre pour traverser tout massif de maçonnerie ou toute fondation (radier ou semelle) et en cas de présence de roches dans le sol. (fig. 2, stade 1)
• une simple tarière sera suffisante pour le forage dans un substrat végétal, argileux ou limoneux. (fig. 2, stade 2).

It can be set up by any company in possession of standard drilling equipment.
Depending on the type of application:

• drilling will be performed using a diamond core drill in the case of undercutting to cross any massive masonry or foundation (raft or footing) and in case of presence of rocks in the soil. (Fig. 2, stage 1)
• a simple auger will be sufficient for drilling in a plant substrate, clay or silt. (Fig. 2, stage 2).

To prevent the drilling of a borehole, a protective sleeve (pipe type, PVC pipe, etc. of the same diameter as the drilled hole) will be inserted into the hole as the auger progresses and withdrawn parallel to the hole. injection. Such techniques are well known to those skilled in the art.

The grout is prepared by mixing the micro-crushed mineral mortar described above with clear water in the proportion of 5 liters per 25 kg of powder. The mixture must be homogeneous and requires a mixer.

With the drilling completed, the pile members descended into the well (Figure 2, Stage 3) by bolting together. (Fig. 2, stage 4)

Then once the mixture obtained, it is injected through a pressure pot (Figure 2, Stage 5). The injection is generally done from the bottom up, starting with the tip, injected independently, at a pressure of 10 bar so as to create a bulb. Then the rest of the pile is always injected from bottom to top at a pressure of 4 bar. The air and possibly the water contained in the soil are evacuated naturally by rising in the wellbore, as and when the injection, the grout being hydrophobic (Figure 2, stage 6).

Those skilled in the art will easily perceive numerous modifications and adaptations with respect to the specific embodiment described above, without departing from the scope of the invention as defined in the following claims.
It should thus be noted that an installation by sinking of the pile according to the invention is also possible, but more difficult because requiring protection of the pile by sealing at its tip of a special plate.

Claims (16)

Foundation pile consisting of a reinforcing structure and a hardening grout, the end of which is provided with a bulb of hardening grout surrounded by an expandable sheath, characterized in that the pile is provided with at least one an expandable sheath surrounding its end and at least one expandable sheath surrounding at least part of its body, and in that said sheaths are such as to confine the hardening grout and respectively form a soil compaction bulb at the end of the pile, and adhere the pile to the ground and / or the structures surrounding the pile. Foundation pile according to claim 1, characterized in that the pile comprises independent grouting ducts at the pile body and at the end of the pile. Foundation pile according to either of Claims 1 and 2, characterized in that the reinforcing structure is formed, at least in part, of a reinforcing tube while at least one expanding sleeve envelopes the end of said armature tube and at least one expandable sheath envelops at least a portion of the body of said armature tube. Foundation pile according to any one of the preceding claims, characterized in that the confinement of the hardening grout results from the mesh of the sheath according to the characteristics of the hardening grout. Foundation pile according to claim 4, characterized in that the hardening grout is a mineral grout, micromilled, anti-swelling, anti-shrinkage and hydrophobic. Foundation pile according to any one of the preceding claims, characterized in that the expandable sheath surrounding the body of said reinforcing tube constitutes a textile sleeve having a diameter between 200 and 300 mm. Foundation pile according to any one of the preceding claims, characterized in that the expandable sheath surrounding the end of said reinforcing tube constitutes a textile sleeve having a diameter between 300 and 600 mm. Micro-pile foundation pile according to one or other of the preceding claims, characterized in that it has a length of between 1.5 and 10 m and a diameter of between 20 and 35 cm. Anchoring method in the soil and / or reinforcing foundations involving the placing of a pile comprising a reinforcing structure, and the injection of hardening grout at the pile body and / or in a sheath expandable to the end of said pile, characterized in that hardening grout is injected into at least one expandable sheath wrapping a part of the body of said pile, so as to adhere the sheath (s) expandable to the ground and / or surrounding structures the pile, and in at least one expandable sheath surrounding the end of said pile, so as to form a soil compaction bulb at the end of the pile. Method according to claim 9, characterized in that the mesh of the sheaths is such as to confine the hardening grout. Method according to either of claims 9 and 10, characterized in that the mesh of the sheath is a function of the characteristics of the hardening grout. A method according to any one of claims 9 to 11, characterized in that the injected hardening grout is a mineral grout, micro grind, anti-swelling, anti-shrink and hydrophobic. Method according to one or more of claims 9 to 12, characterized in that the hardening slurry is independently injected at the pile body and at the end of the pile. Method according to claim 13, characterized in that the control of the pile abutment is carried out by controlling the pressure of the grout at the end and the body of the pile. Method according to one or more of claims 9 to 14, characterized in that the method is used for anchoring in the ground, laying foundations and / or reinforcing existing or new structures. Method according to one or the other of claims 9 to 15, characterized in that the method uses micro-piles having a length between 1.5 and 10 m and a diameter between 20 and 35 cm.

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