FR3076562A1 - PIEU IN BFUP - COMPOSITE PIEU - Google Patents

Abstract

Pile (1) comprising an upper portion (10) connected to a lower portion (20) by a central tubular portion (30) whose section (33) has an outer central diameter (D34) and an inner central diameter (D35), - the upper portion (10) a first frustoconical housing (14) opening into the central housing (31), - the upper portion (10) comprises a strapping (17) whose outer diameter is substantially equal to or less than the outer central diameter ( D34); and Composite pile

Description

FIELD OF THE INVENTION

The present invention relates to the field of piles for foundations of civil engineering works or buildings and more particularly beaten piles made of Ultra High Performance Fiber Concrete (UHPC).

BACKGROUND OF THE INVENTION

When making foundations for civil engineering works, such as crossing bridges, or buildings, it is known to beat or drill piles or micropiles in order to be able to rely on a ground by peak effect or by friction.

The piles can be made of wood, metal or reinforced concrete, and generally include a metal point in their lower portion. The upper portion of the pile generally includes a metal protection so that the wood or concrete does not crush under the blows of the threshing machine. The pile is generally tubular and the central portion extending between the lower portion and the upper portion comprises a cylindrical housing into which concrete can be poured after threshing of the pile. Armatures can, if necessary, also be introduced into the cylindrical housing. Generally, a composite pile is obtained by assembling a first pile on a second pile. The lower portion of the first pile is then engaged in the upper portion of the second pile which is at least partially sunk into the ground and a weld bead is produced to guarantee a connection and good alignment of the piles. The implementation of such a weld bead is delicate on site and long. Finally, since the piles are generally driven in wet soils, the durability of the weld bead, and therefore the integrity of the pile, is uncertain. Indeed, a rupture of the weld bead, for example under the effect of corrosion, can lead to a relative misalignment of the first and of the second pile, leading to a significant reduction in the loads that can be applied to the composite pile, to local decompression. of the ground, or even a rupture of the stake.

There are also composite piles whose connection between the piles is ensured mechanically, for example by screwing. It is then necessary to manipulate the first pile so as to make the holes coincide, which can be particularly delicate when the piles have large dimensions. Finally, it is necessary to provide devices ensuring that the connection is very stable over time, such devices have a relative durability or a significant cost.

OBJECT OF THE INVENTION The object of the invention is to improve the reliability of a battered concrete pile and / or to facilitate its implementation.

SUMMARY OF THE INVENTION For this purpose, a pile made of material comprising cement is provided, comprising an upper portion connected to a lower portion by a tubular central portion defining a central housing. The central portion includes at least one cylinder-shaped section with a longitudinal axis, a section of which has an outside central diameter and an inside central diameter. The upper portion has a first wall delimited by a first interior surface and a first exterior surface. The lower portion has a second wall delimited by a second interior surface and a second exterior surface. The first wall defines a first frustoconical housing opening into the central housing, a first large base circle of the first housing has a first large diameter and a first small base circle of the first housing has a first small diameter. The second outer surface defines a tubular frustoconical part opening into the central housing, a second large base circle of the frustoconical part has a second large diameter and a second small base circle of the frustoconical part has a second small diameter. The upper portion comprises a hoop whose inner surface extends around the first outer surface and an outer diameter of the hoop is substantially equal to or less than the outer central diameter. The second large diameter is greater than the first large diameter and / or the second small diameter is greater than the first small diameter. The first small diameter and / or the second small diameter being less than the inner central diameter.

A light tubular pile is thus obtained, the internal geometry of which easily blocks two piles which would be mounted one on the other during the construction phase. Indeed, the presence of a strapping coupled to the difference in diameters between the conical portion and the conical housing allows rapid assembly of the two piles one on the other in the construction phase. The strapping maintains a radial tension at the pile junction which blocks the two piles longitudinally. Finally, the tubular geometry of the pile makes it light, easy to handle and allows concrete to be poured inside. The change in section at the junction of two piles and which is created by the particular relationship between the first small diameter, the second small diameter and the inner central diameter makes it possible to create a lock once the concrete in the central housing has taken. The blocking obtained by the design of the composite pile of the invention is sufficient during threshing operations. The locking obtained thanks to the internal geometry of the composite pile is sufficient once the pile is in the ground, independently of the oxidation of the strapping.

A particularly light and resistant pile is obtained when the material comprising cement is Ultra High Performance Fiber Concrete.

Optimal compression of the material comprising cement is obtained when the difference between the first large diameter and the second large diameter is between 0.1 and 0.5 millimeters, and is preferably equal to 0.3 millimeters.

It is possible to inject the soils when the pile comprises at least one channel extending in a substantially radial direction, the channel connecting the central housing and an external surface of the pile.

The locking of a pile on the other is particularly effective when the strapping is made of metal, and advantageously of steel with High Elastic limit.

An economical realization is obtained when the strapping is in the form of a straight cylinder. The invention also relates to a composite stake comprising at least a first and a second stake previously described in which the lower portion of the second stake is engaged in the upper portion of the first stake. The composite pile is particularly durable when the central housing is filled with concrete. Other characteristics and advantages of the invention will emerge on reading the following description of a particular embodiment of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Reference will be made to the appended figures, among which: - Figure 1 is a schematic view in longitudinal section of a pile according to the invention; - Figure 2 is a schematic view of a section of the pile of the pile according to the invention; - Figure 3 is a partial schematic view in longitudinal section of an upper portion of the pile of the pile according to the invention; - Figure 4 is a schematic perspective view of the housing of the upper portion of the pile according to the invention; - Figure 5 is a partial schematic view in longitudinal section of a lower portion of the pile of the pile according to the invention; - Figure 6 is a schematic perspective view of a frustoconical portion of the lower portion of the pile according to the invention; - Figure 7 is a schematic view in longitudinal section of a lower portion of a composite pile according to the invention; - Figure 8 is a schematic view in longitudinal section of a central portion of a composite pile according to the invention; - Figure 9 is a schematic view in longitudinal section of detail of a lower portion of a composite pile according to the invention; - Figure 10 is a schematic view in longitudinal section of a composite pile according to one invention; - Figures 11.a to 11.e are schematic representations of the steps for implementing a composite pile according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

Referring to Figures 1 to 9, the pile according to the invention, and generally designated 1, has a substantially cylindrical shape and is made of Ultra High Performance Fiber Concrete (UHPC). The pile 1 comprises an upper portion 10 connected to a lower portion 20 by a tubular central portion 30 defining a central housing 31. The central portion 30 comprises a section 32 in the form of a straight cylinder with a longitudinal axis Oy. The section 32 has a section 33 which has an outer central diameter D34 (here three hundred and fifty millimeters) and an inner central diameter P.35 ·

As can be seen in FIG. 3, the upper portion 10 comprises a first wall 11 delimited by a first interior surface 12 and a first exterior surface 13. The first wall 11 delimits a first frustoconical housing 14 opening out into the central housing 31. The first housing 14 frustoconical, represented in FIG. 4, is defined by a first circle of large base 15 which has a first large diameter D15 and a first circle of small base 16 of the first housing which has a first small diameter D16. The first large base circle 15 and the first small base circle 16 are here included in planes P45 and P16 perpendicular to the longitudinal axis Oy.

A strapping 17 made of S355J2N type steel (according to standard NF EN 10113) extends around the first wall 11. The strapping 17 is in the form of a straight cylinder with a longitudinal axis Oy and has an inner surface 17.1 which extends around the first external surface 13, and is preferably in contact with the first external surface 13. The strapping 17 also comprises an external surface 17.2 whose external diameter P17.2 is substantially equal to the central external diameter D34.

As shown in FIG. 5, the lower portion 20 comprises a second wall 21 delimited by a second interior surface 22 and a second exterior surface 23. The second exterior surface 23 delimits a tubular frustoconical part 24 opening into the central housing 31. The frustoconical part 24, represented in FIG. 6, is defined by a second large base circle 25 which has a second large diameter D25 and a second small base circle 26 which has a second small diameter D26 ·

According to the invention, the second large diameter D25 is greater than the first large diameter D15 by a difference of large diameter D and the second small diameter D26 is greater than the first small diameter D16 by a difference of small diameter d.

The large diameter difference D is ideally between 0.1 and 0.5 millimeters and preferably equal to 0.3 millimeters.

The difference in small diameter d is ideally between 0.1 and 0.5 millimeters and preferably equal to 0.3 millimeters.

According to the invention also, the first small diameter D16 is less than the inner central diameter D35 and the second small diameter D26 is less than the inner central diameter D35.

Such a pile can be obtained by internal machining of a UFPP preform or by core molding methods whose shape is modifiable known to those skilled in the art.

Advantageously, the central portion 30 of the pile 1 comprises a first series 2 of six channels 2.1 to 2.6 which extend in a substantially radial direction connecting the central housing 31 and an outer surface 3 of the pile 1. The first series 2 of six channels 2.1 to 2.6 is located near the upper portion 10 of the pile 1. A second series 4 of six channels 4.1 to 4.6, a third series 5 of six channels 5.1 to 5.6 and a fourth series 6 of six channels 6.1 to 6.6 similar to the first series 2 are regularly installed on the central portion 30 between the upper portion 10 and the lower portion 20 of the pile 1. The channels 2.1-2.6, 4.1-4.6, 5.1-5.6 and 6.1-6.6 can be produced during the molding of the pile 1 or drilled after manufacturing pile 1.

The implementation of the invention will be described in application to the threshing of a composite pile 100 comprising a first pile 1 and a second pile 51, identical to pile 1. The elements identical or similar to those described above will bear an identical reference increased by fifty when it concerns the second pile 50.

With reference to FIGS. 7 to 10, the lower portion 20 of the first pile 1 is introduced into a housing 40 with a point 41 made of metal. The pile 1 is then beaten using a sheep (not shown) and sinks into the ground 45. Once the pile 1 is sufficiently sunk into the ground 45, the lower portion 70 of a pile 51 is presented facing the upper portion 10 of the first pile 1 so that the frustoconical part 74 of the second pile cooperates with the frustoconical housing 14 of the first pile 1. The frustoconical geometries of the frustoconical part 74 and of the housing 14 facilitate the approach and the relative positioning of piles 1 and 51.

As visible in FIG. 9, the difference between the second large diameter D75 of the frustoconical part 74 of the second pile 51 and the first large diameter D15 of the housing 14 of the first pile 1 as well as the difference in diameter between the second small diameter D76 of the frustoconical part 74 of the second pile 51 and the first small diameter D16 of the housing 14 of the first pile 1 keeps the lower portion 70 of the second pile 51 away from the upper portion 10 of the first pile 1. From the first impact of the sheep on the portion upper 60 of the second pile 51, the frusto-conical portion 74 of the second pile 51 is inserted into the housing 14 and comes to compress the BFUP of the first wall 11 of the first pile 1 as well as the BFUP of the second wall 21 of the second pile 51. The strapping 17 of the first pile 1 takes up these radial forces and, by preventing the shearing of the first wall 11, achieves a prestressing junction between the first wall i 11 of the first pile 1 and the second wall 71 of the second pile 51.

The threshing of the composite pile 100 continues until the upper portion 60 of the second pile 50 is at the height of the finished soil (FIG. 10). The fact that the outside diameter P17 -2 of the hoop 17 of the first pile 1 is substantially equal to the outside central diameter D8s of the first pile 1 avoids decompression of the soil located along the second pile 51. A similar effect is obtained when the outside diameter P17 -2 of the strapping 17 of the first pile 1 is substantially less than the central outside diameter D35 of the first pile 1. The interior of the composite pile 100 is then poured using an injection hose 46 provided with a shutter lower 46.1 and an upper shutter 46.2 according to a technique known to a person skilled in the art under the name of soil fracturing - or pile-breaking - which is shown by way of illustration in FIGS. 11. a to 11.e. The volume of concrete which extends between the central housing 31 of the first pile 1 and the central housing 81 of the second pile 51 comprises a portion 47, here substantially in the form of an hourglass, which provides relative locking of the first pile 1 and the second pile 2. In fact, the fact that the first small diameter D16 of the first pile 1 is less than the inner central diameter D35 of the first pile creates a reduction in section of the portion 47 which, once the concrete has poured into the central housing 31 has taken, prohibited a relative longitudinal or transverse movement of the first pile 1 and the second pile 51. A similar reduction in section, but symmetrical, takes place due to the fact that the second small diameter D76 of the second pile 51 is less than the central diameter interior D8s of the second pile 51. This concrete lock can advantageously be reinforced by the introduction of one or more bars or strands of reinforcement, which greatly improves the tensile strength of the portion 47 along the longitudinal axis Oy.

A composite pile 100 is thus obtained, the components of which are easily transportable. The relative positioning of the first and second piles 1 and 51 of the composite pile 100 and the maintenance of their junction is rapid and reliable due in particular to the prestressing of the concrete at the joint. Finally, the reinforced concrete lock between the first pile 1 and the second pile 51 is protected by UHPC, which greatly improves the durability and reliability of the junction regardless of the resistance over time of the metal strapping.

Of course, the invention is not limited to the embodiments described but encompasses any variant coming within the scope of the invention as defined by the claims.

In particular, - although the invention is described here in connection with the manufacture of a pile with an outside diameter of 350 mm, the invention also applies to the manufacture of piles of different diameter, preferably between 120 and 350 millimeters but also diameters less than 120 millimeters or greater than 350 millimeters; - Although here the central portion comprises a section in the form of a straight cylinder, the invention also applies to a central portion comprising more than one section in the form of a right cylinder; - although here the pile is UHPC, the invention also applies to other materials comprising cement such as for example standard concrete or mortar; - the pile can have other shapes, internal and / or external, than those described; - although here the pile comprises four series of six radial connecting channels connecting the central housing and an external surface of the pile the invention also applies to a different number of channels, for example between one and five or more six channels. These channels can also extend in directions that are not radial, as long as the distal end of these channels opens onto an external surface of the pile. - although here the strapping is made of S355J2N steel, the invention also applies to other types of strapping such as for example a mineral fiber strapping such as carbon or kevlar, or in other types of steel High elastic limit (called HLE) whose elastic limit is greater than or equal to three hundred and fifty-five

Newtons per square millimeter, mild steels, alloyed or not, possibly stainless, or non-ferrous metals; - although here the outer diameter of the outer surface of the hoop is substantially equal to the outer central diameter of the central portion, the invention also applies to a hoop whose outer diameter of the outer surface is substantially less than the central diameter outside of the central portion; - although here the second large diameter of the frustoconical part is greater than the first large diameter of the frustoconical housing and the second small diameter is greater than the first small diameter, the invention also applies to a frustoconical part of which only the second large diameter of the frustoconical part is greater than the first large diameter of the frustoconical housing or a frustoconical part of which only the second small diameter is greater than the first small diameter; - although here the composite pile comprises a first and a second pile, the invention also applies to a composite pile comprising more than two piles; - although here the first circle of large base, the first circle of small base, the second circle of large base and the second circle of small base defining the first frustoconical housing and the frustoconical part are included in planes perpendicular to the longitudinal axis, the invention also applies to other types of frustoconical housing and of frustoconical first part in which the first circle of large base and / or the first circle of small base and / or the second circle of large base and / or the second small base circle are included in planes having any orientation relative to the longitudinal axis; - although here the central portion comprises at least one section in the form of a straight cylinder, the invention also applies to other types of cylinder shape such as a cylinder whose base curve is oval, polygonal or any.

Claims (9)

1. Pile (1) of material comprising cement, comprising an upper portion (10) connected to a lower portion (20) by a tubular central portion (30) defining a central housing (31), the central portion (30) comprises at least one cylinder-shaped section with a longitudinal axis, a section (33) of which has an outer central diameter (D34) and an inner central diameter (D35), in which: - the upper portion (10) has a first wall ( 11) delimited by a first interior surface (12) and a first exterior surface (13), - the lower portion (20) comprises a second wall (21) delimited by a second interior surface (22) and a second exterior surface (23 ); - The first wall (11) delimits a first frustoconical housing (14) opening into the central housing (31), a first large base circle (15) of the first housing (14) has a first large diameter (D15) and a first small base circle (16) of the first housing (14) has a first small diameter (D16); the second outer surface (23) delimits a frustoconical tubular part (24) opening into the central housing (31), a second large base circle (25) of the frustoconical part (24) has a second large diameter (D2s) and a second circle of small base (26) of the frustoconical part (24) has a second small diameter (D26); - The upper portion (10) comprises a hoop (17) whose inner surface (17.1) extends around the first outer surface (13); in which, an outside diameter (P17-2) of the hoop (17) is substantially equal to or less than the outside central diameter (P34); and the second large diameter (P25) is greater than the first large diameter (P15) and / or the second small diameter (P26) is greater than the first small diameter (D46); - the first small diameter (P16) and / or the second small diameter (D26) being less than the inner central diameter (P35). 2. Pile (1) according to claim 1, in which the material comprising cement is Ultra High Performance Fiber Concrete. 3. Pile (1) according to any one of the preceding claims, in which the difference between the first large diameter (Pis) and the second large diameter (P2s) is between 0.1 and 0.5 millimeters, and is preferably equal to 0.3 millimeters . 4. Stake (1) according to any one of the preceding claims, in which the stake (1) comprises at least one channel (2.1-2.6; 4.1-4.6; 5.1-5.6; 6.1-6.6) extending in a direction substantially radial, the channel (2.1-2.6; 4.1-4.6; 5.1-5.6; 6.1-6.6) connecting the central housing (31) and an external surface (3) of the pile (1). 5. Pile (1) according to any one of the preceding claims, in which the hoop (17) is made of metal. 6. A pile (1) according to claim 5, in which the strapping (17) is made of high elastic limit steel. 7. Pile (1) according to any one of the preceding claims in which the hoop (17) is in the form of a straight cylinder. 8. Composite pile (100) comprising at least a first and a second pile (1; 51) according to one of the preceding claims in which the lower portion (70) of the second pile (51) is engaged in the upper portion (10 ) of the first stake (1). 9. Composite pile (100) according to claim 8, wherein the central housing (31) is filled with concrete.