EP0725186A1 - Profile, apparatus and method for realizing a consolidation pile - Google Patents

Abstract

The column consists of an H-section member (1, 2, 3) equipped with one or more first deflector panels (4A) between its side flanges (2, 3) which slopes upwards and outwards, and at least one second deflector panel (4B) which slopes downwards and outwards. The deflector panels are flat and can be made from two sections of a single metal sheet, bent at an angle to one another. The deflector panels are set at an angle of some 45 degrees to the centre rib (1) of the H-section member and extend to the outer edge of the flanges without going beyond them. The panel surfaces can have inclined ribs, and the first panels (4A) have holes (10) in them for injected liquids. The column can be driven into the ground by vibration.

Description

The invention relates to a technique for producing ballasted columns enabling them to be produced even under particularly difficult conditions while using more efficient, simpler and less expensive means of execution than conventional vibrating needles.

The ballasted columns are useful in particular for improving a ground for example to consolidate a median, by formation in the ground of columns in filler material.

The vibrating needles develop a horizontal vibration which is very effective in making part of the filler materials penetrate through the natural soil and in compacting the ballasted column well. On the other hand, the inherent defect in the sense of vibration is the difficulty in penetrating relatively resistant layers of soil in order to go and execute beneath these columns ballasted in less resistant layers.

Conversely, commercial vibro-diggers exert a solely vertical vibration which makes it possible to easily insert a profile into soil, even relatively resistant, but which does not allow the production of ballasted columns, unless these profiles are arranged according to the features of the present invention.

According to the invention, a profile is used which has an H-shaped cross section end portion, this portion comprising, between the wings of the H and on each side of the vertical core of the profile, at least one first sheet inclined upwards and outwards from the profile, and at least one second sheet inclined upwards and inwards from the profile.

These deflector sheets are generally flat but they can be curved, have any desired profile, regular or irregular.

• buter efficacement les matériaux constitutifs de la colonne ballastée,
• régler la fréquence de vibrations du vibro-fonceur pendant l'exécution, ce que ne permet pas l'utilisation d'une aiguille vibrante.

The invention makes it possible in particular to obtain the following advantages:

• effectively abut the constituent materials of the ballasted column,
• adjust the vibration frequency of the vibrator during execution, which does not allow the use of a vibrating needle.

Preferably, to improve the descent of the profile by facilitating the evacuation of the initial soil at the location of the ballasted column, the profile is provided with launching tubes to inject a fluid, usually water.

The wings of the profile can also be provided on their external faces with ribs inclined downwards.

An embodiment of such a profile will be described below, with reference to the figures of the attached drawing and the description and the figure will reveal other important features of the profile of the invention.

• la fig. 1 est une perspective schématique de l'extrémité inférieure du profilé ;
• la fig. 2 est un schéma du dispositif de vibro-fonçage, le profilé étant vu en coupe par un plan vertical passant par l'axe du profilé et perpendiculaire à l'âme du profilé ;
• la fig. 3 est une vue du profilé dans le sens de la flèche F de la fig. 1;
• la fig. 4 est une latérale de l'extrémité inférieure du profilé, et
• la fig. 5 est une coupe du profilé par un plan horizontal situé au dessus des tôles déflectrices.

In the figures:

• fig. 1 is a schematic perspective of the lower end of the profile;
• fig. 2 is a diagram of the vibro-sinking device, the profile being seen in section through a vertical plane passing through the axis of the profile and perpendicular to the web of the profile;
• fig. 3 is a view of the profile in the direction of the arrow F in FIG. 1;
• fig. 4 is a side of the lower end of the profile, and
• fig. 5 is a section of the profile by a horizontal plane located above the deflector plates.

The vibro-driving device essentially comprises a vibratory digger V on the market and a profile according to the invention subjected to the action of the vibro-digger to produce in the soil S a ballasted column.

The vibro-driving profile shown in the figures is an H-shaped profile consisting of a core (1) between two wings (2,3).

According to the invention, the profile is provided at one end, on each side of its core 1, with a sheet (4; 4 ') which has been bent so as to constitute a lower wall (4A; 4'A) ) inclined upwards from the core 1 and an upper wall (4B; 4'B) inclined downwards from this core.

The lower edge (4a) of the wall (4A) and the upper edge (4b) of the wall (4B) are welded to the core, while the lateral edges (4c, 4d) of the walls are welded to the internal faces ( 2a, 3a) wings (2,3). Likewise for the walls 4'A and 4'B.

In the example shown, the deflecting sheets extend from one wing to the other and do not leave the volume defined by the wings of the profile.

The angle formed by the core (1) and each inclined sheet (4A, 4B) is preferably at most equal to 45 ° and the angle formed by the core and the deflector (4A) which rises outwards of the profile is preferably greater than that formed by the core and the deflector (4B) which rises towards the inside of the profile.

The wings of the profile are further provided on their outer faces (2b, 3b) with ribs (5, 6) inclined downward from the plane P of the core, symmetrically on each side of this plane.

The launching tubes are vertical tubes (7,8) located for example in the corners formed by the core and the wings for injecting water or other suitable liquid near the deflectors (4A, 4B), these tubes being possibly protected by fairings (9).

These vertical tubes 7 and 8 preferably open at the bottom in the enclosure formed by the sheets (4A, 4B) and the core of the profile and in the symmetrical enclosure (4'A, 4'B), the sheets ( 4A and 4'A) being provided with drainage holes (10) allowing the liquid to be injected below the sheets (4A and 4'A).

The principle of implementation is as follows:

Phase 1.

The profile is lowered into the ground by vibro-driving and preferably by associated launching to the depth of the ballasted column to be produced.

In this descent the sheets (4A and 4'A) have the effect of pushing the natural soil outwards by two associated phenomena, their inclination and the vertical vibration of the profile which turns into inclined vibration on the ground.

This creates a chimney in the ground.

The launching facilitates the penetration and eliminates, by going up in the chimney, the finest materials, in particular the vases.

Phase 2.

The profile is raised and lowered several times, of the order 2 to 5 times, maintaining the vibration and the launching so as to "sweep" this chimney and to enlarge it.

Phase 3

The launching pressure is then reduced, the vibration is maintained and the constituent material of the ballasted column is introduced, while raising the profile in passes of about 50 cm, going back and forth by 1 m, thus ensuring good compaction of the ballasted column. The sheets (4B and 4'B) are intended to facilitate the raising of the profile and the descent of the material into the chimney. The external ribs of the profile facilitate the descent of the material of the columns and the launching facilitates the installation, while purging any falls of bad soil due to the local collapses of the walls of the chimney.

• la capacité de pénétration verticale, apportée par l'utilisation d'un vibro-fonceur, permet de pénétrer les éventuelles couches résistantes que peut présenter la structure du sol. En particulier, certaines structures du sol présentent des alternances de sable et gravier de bonne qualité et de couche d'argile molle ou de terrains compressibles dans lesquelles la technique d'amélioration par colonnes ballastées présente tout son intérêt. Si les couches résistantes dépassent 2 à 3 m, elles ne peuvent en général être pénétrées par les aiguilles classiques tandis que la présente invention permet de le faire.
• la simplification apportée à la réalisation de colonnes ballastées dans des sites fluviaux ou maritimes sur lesquelles on veut établir, par exemple, un quai ou une digue. La méthode par aiguilles vibrantes nécessite en général la mise en place des matériaux à l'aplomb de l'aiguille au fur et à mesure de la réalisation de chaque colonne ballastée, surtout si celles-ci sont très profondes. Elle oblige donc à l'installation d'un système d'approvisionnement continu, par tapis par exemple, à partir de pontons divers. La possibilité apportée par l'invention de traverser des couches résistantes épaisses, permet de déposer d'abord, par simple clapage par exemple, une forte épaisseur de matériau de bonne qualité à l'emplacement de la surface de sol à traiter et à traverser cette couche avec le profilé pour réaliser la colonne.

Among the improvements to the conventional technique brought by this invention, we can cite:

• the vertical penetration capacity, provided by the use of a vibrator, makes it possible to penetrate any resistant layers that the soil structure may have. In particular, certain soil structures have alternating good quality sand and gravel and a layer of soft clay or compressible soils in which the technique of improvement by ballasted columns is very useful. If the resistant layers exceed 2 to 3 m, they cannot generally be penetrated by conventional needles while the present invention makes it possible to do so.
• the simplification brought to the realization of columns ballasted in river or maritime sites on which one wants to establish, for example, a quay or a dike. The vibrating needle method generally requires the placement of materials directly above the needle as each ballasted column is produced, especially if they are very deep. It therefore requires the installation of a continuous supply system, by carpet for example, from various pontoons. The possibility provided by the invention to pass through thick resistant layers, makes it possible to deposit first, by simple clapage for example, a large thickness of good quality material at the location of the floor surface to be treated and to pass through this layer with the profile to make the column.

• la réduction du coût d'exécution des colonnes ballastées, la présente invention pouvant être mise en oeuvre à partir de moyens simples que possède ou peut trouver facilement toute entreprise exécutant des travaux de fondation, et dont les dimensions peuvent être facilement choisies en fonction des besoins, ce qui n'est pas le cas des aiguilles vibrantes.
• tous les avantages liés à l'utilisation d'un vibro-fonceur qui reste en permanence à l'extérieur de la colonne ballastée.

This working method can also be used on land sites with ballasted columns.

• the reduction in the cost of execution of the ballasted columns, the present invention being able to be implemented using simple means which any company carrying out foundation works has or can easily find, and the dimensions of which can be easily chosen according to needs , which is not the case with vibrating needles.
• all the advantages linked to the use of a vibrator-digger which remains permanently outside the ballasted column.

The invention is not limited to the embodiment which has been described.

Claims (11)

Profile to descend into the ground to make a ballasted column, characterized in that the profile has an end portion with a cross section in the form of an H which comprises, between the wings (2,3) of the profile, on each side of the 'core (1) of the profile, at least a first baffle plate (4A, 4'A) inclined upward and outward of the profile and at least a second baffle plate (4B, 4'B) inclined upward and towards the inside of the profile. Profile according to claim 1, in which the deflecting sheets (4A, 4B) are planar. Profile according to claim 1 or 2, in which the deflecting sheets consist of two parts of the same curved sheet (4). Profile according to one of claims 1 to 3, wherein the core (1) of the profile makes with each inclined sheet an angle at most equal to 45 °. Profile according to one of claims 1 to 4, in which the deflector plates (4A, 4B; 4'A, 4'B) extend from one wing to the other and do not leave the volume defined by the wings . Profile according to one of claims 1 to 5, in which the wings (2,3) of the profile are provided on their external faces (2b, 3b) with ribs (5) inclined downwards from the plane (P) of the soul (1). Profile according to one of claims 1 to 6 in which vertical tubes (7,8) are provided for the injection of a liquid near the inclined sheets (4A, 4B). Profile according to Claim 7, in which the vertical tubes (7, and 8) open out at the bottom into the enclosure formed by the sheets (4A, 4B) and the core of the profile and into the symmetrical enclosure (4'A, 4'B and core), the first sheets (4A, 4'A) being provided with discharge holes (10) allowing the liquid to be injected below the first sheets (4A, 4'A). Device for realusing a ballasted column, characterized in that it comprises a vibratory digger (V) and a profile (1-3) according to one of claims 1 to 8 subjected to the action of the vibratory digger. Method for making a ballasted column, characterized in that the column is made by vibro-sinking into the ground of a profile according to one of claims 1 to 8. Method according to claim 10, characterized in that a launch is associated with vibro-driving.

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