EP0596792B1 - Improved device for treating soil using rotating jets - Google Patents

Abstract

The invention relates to a device for treating the land by a jet comprising a string (1) of rods or tubes (2) coupled to one after another, a device (7, 8) for driving the string of rods or tubes in terms of rotation and, if desired, in terms of translation, mounted on the upper part of the said string, at least one ejection nozzle (4, 5) provided at the lower part of the said string, at least one source (11, 13) of fluid under high pressure, and a pipe connecting the source of high pressure fluid to the said nozzle, characterized in that the device for driving the string of rods or tubes imparts to the latter a reciprocating rotational movement and the feed pipe consists of a flexible hose (10, 12) connecting the said source to the said nozzle. Use in the civil engineering field. <IMAGE>

Description

The invention relates to an improved device for the treatment of floors by rotary jet (s).

The process of soil treatment by rotary jet (s) is well known and is used for the production of reinforcing elements in the form of columns and that of waterproofing screens in the mass of permeable ground.

According to this method, an exogenous material or grout is introduced into the terrain considered from a borehole in the form of at least one jet suitably oriented at high speed which, on its path, destructs the terrain in place, and, according to the nature of the said ground, either mixes with the constituent elements of the latter and leads, after setting, to the formation of a mortar or concrete of soil (case, for example, gravelly or sandy grounds), or replaces purely and simply the ground and leads, after setting, to the formation of a hardened grout (case, for example, clayey grounds). The jet (s), depending on the flow rate, the driving pressure and the characteristics of the terrain, have a certain radius of action. If the tool ensuring the formation of the jet is set in slow rotation-translation inside the borehole, a more or less cylindrical volume of treated ground is obtained having as a radius the radius of action of the jet (s) under the conditions considered. , and a height corresponding to the amplitude of the translational movement.

It is easily understood that it is thus possible to produce, by this jet technique, sealing screens by the juxtaposition of a plurality of cylindrical elements (or columns) of ground thus treated over a certain height, made from a mesh of parallel boreholes of density such that the elements or columns overlap so as to constitute a continuous solid mass.

The jets used can be of various types, that is to say consist of a simple grout jet, or a grout jet surrounded by an annular air jet to increase the radius of action , or a combination of a water jet surrounded by an annular air jet ensuring the destructuring of the ground and a separate grout jet, usually provided at a level lower than that of the water jet.

For the implementation of this process, a device is usually used comprising a central for producing a cement grout supplying grout to one or more pumps connected, via a rotating joint, to a train of tubes introduced into the borehole where the jet treatment is to be carried out. The tube train can be driven in translation and rotation by means of a hydraulic rotary head enclosing the upper end of the tube train, which is itself mounted on a drilling slide. The pump or pumps deliver the destructuring fluid (grout or water) at pressures of the order of 200 to 700 bars or more.

The tube train is formed of connectable unitary tubular sections provided with suitable seals and each section can be formed of a single tube (single jet) or of several coaxial tubes (double or triple jet). Liquids (grout, water) are ejected through one or more nozzles with a diameter of 2 to 4 mm approximately. The tube train sections can have a diameter of approximately 50 to 200 mm.

A drilling tool can also be provided, below the nozzles, at the lower end of the tube train to carry out the drilling in which the treatment will be carried out. Alternatively, drilling can be performed beforehand by a separate device.

In practice, the jet treatment is started by positioning the jet device at the bottom of the borehole, driving the tube train in a rotational and translational movement towards the head of the borehole until a column of land is obtained. treated of the desired height. During this translational movement the upper part of the train of tubes protrudes more and more relative to the surface of the ground. This poses no problem when working under normal site conditions, for example in the open air.

It happens, however, that we have to work in such conditions (reduced height ceiling, narrow working chamber, etc.) that we do not have in the axis of the drilling the necessary space to raise the train of tubes during processing. In this case, it must be dismantled, during processing, to remove the upper tubular section of the train.

Such disassembly is however undesirable, in the case of coaxial tubes defining two or more supply channels, because it creates the risk of grout entering the air or water supply channel, which resumption of treatment damages or clogs the ejection nozzles. Also, during disassembly, it is necessary to stop the supply of fluids and there is the risk that there will then occur an untimely return of ejected grout coming to clog the nozzles.

Finally, it should be noted that the coaxial tube trains are, in general, relatively expensive.

There is therefore a need for a jet treatment device which would make it possible to work in low ceiling or confined spaces without having to interrupt the treatment during a shortening of the train of tubes.

There is also a need for a jet device which does not require the use of expensive coaxial tubes.

The invention aims precisely to meet these needs.

• un train de tiges ou tubes raccordés les uns à la suite des autres,
• un dispositif d'entraînement du train de tiges ou tubes en rotation et, si désiré, en translation monté sur la partie supérieure dudit train,
• au moins une buse d'éjection prévue à la partie inférieure dudit train,
• au moins une source de fluide sous haute pression, et
• un conduit d'alimentation reliant la source de fluide sous haute pression à ladite buse,

caractérisé en ce que :

• le dispositif d'entraînement du train de tiges ou tubes imprime à ce dernier un mouvement de rotation alternative, et
• le conduit d'alimentation reliant ladite source à ladite buse consiste en un tuyau flexible disposé extérieurement audit train.

More particularly, the invention relates to a device for field treatment by jet comprising

• a string of rods or tubes connected one after the other,
• a device for driving the train of rods or tubes in rotation and, if desired, in translation mounted on the upper part of said train,
• at least one ejection nozzle provided at the bottom of said train,
• at least one source of fluid under high pressure, and
• a supply conduit connecting the source of fluid under high pressure to said nozzle,

characterized in that:

• the device for driving the drill string or tubes gives the latter an alternating rotational movement, and
• the supply conduit connecting said source to said nozzle consists of a flexible pipe disposed outside said train.

The device of the invention will usually include one, two or three grout ejection nozzles, more possibly water nozzles. When two or three grout nozzles are present, they will usually be directed in different directions, 180 ° (case of two nozzles) or 120 ° (case of three nozzles) from each other.

Each flexible hose can feed a single nozzle or multiple nozzles through a distributor.

The flexible pipe (s) can be left free or kept in contact with or near the outside surface of the drill string or tubes, for example by fixing them in loops secured to the drill string or tubes or by inserting them into recesses provided on the drill string or tubes.

In addition to the presence of flexible pipes, the device of the invention is characterized in that the drive device gives the train of rods or tubes an alternative rotational movement doubled, when desired, with a translational movement. The angle of rotation in one direction, then in the other depends on the number, type, and relative positioning of the ejection nozzles.

For a device comprising a single grout ejection nozzle, the rotation angle will be 360 ° (one complete revolution) in one direction, then in the other. For a device comprising two grout ejection nozzles oriented 180 ° from one another, the angle of rotation may be 180 ° (half a turn) in one direction, then in the other. The point is that all of the land surrounding the borehole where the device of the invention is placed, is treated during the alternative rotation cycle.

In particular situations, such as in the vicinity of obstacles, the angle of rotation may be limited so as not to voluntarily cover the entire terrain surrounding the borehole.

In the device of the invention, the train of tubes no longer serves as a fluid supply conduit and has only a mechanical function, namely to transmit to the nozzles the alternating and possibly translational movement that it imparts to it the drive device. As a result, the train no longer needs to be hollow and the train of hollow tubes can be replaced by a train of solid rods, if desired.

When it is therefore desired, for any reason, to shorten the train of rods or tubes, during the ascent of the latter, it suffices to remove the section (s) of upper rod or tube (s) from said train , this removal can easily be carried out without having to interrupt the fluid supplies because they are provided by the flexible hoses. Any risk obstruction of the nozzles is thus avoided.

Optionally but preferably, a reel can be provided for each of the flexible pipes present to facilitate the descent of the jet device of the invention in the drilling and then its rise, thus avoiding the presence of flexible pipes scattered on the ground which could be dangerous due to the high pressure of the conveyed fluids.

For the rest, the structure and the implementation of the jet device of the invention are similar to those of the devices of the prior art and it therefore seems entirely superfluous to describe them in detail.

The description which follows, made with reference to the single appended figure, will make the present invention well understood.

The single figure is a schematic view of a device according to the invention.

In this figure is shown a train 1 of elementary tubes 2 connected to each other, to the lower part of which is fixed a terminal element 3 equipped with two ejection nozzles 4 and 5 and a drilling tool 6.

The train 1 is capable of being driven in alternating rotation and / or in translation by a drive device consisting of a hydraulic rotary head 7 enclosing the upper end of the train, itself mounted on a slide 8 substantially parallel to the train of tubes. As shown in the figure, the tool 6 is of a diameter greater than that of the tube train in order to provide a free annular space between said train and the drilling wall 9 produced by the tool 6 in the ground. The nozzle 4 is connected by a flexible pipe 10 to a source 11 of water under high pressure, while the nozzle 5 is connected by a flexible pipe 12 to a source 13 of grout curable under high pressure. As illustrated, reels 14 and 15, for pipes 10 and 12, respectively, are provided on the surface, for winding or unwinding the flexible pipes in order to adjust their length to the needs and prevent them from dragging on the ground, this which in the event of sudden variations in fluid pressure could cause dangerous "lashes".

The train 1 of tubes no longer serving as a fluid conduit (s), there is nothing to prevent it from being shortened, as necessary, during its ascent by removing the upper tube section located above the head 7.

It goes without saying that the embodiment described is only an example and that it could be modified, in particular by substitution of technical equivalents, without departing from the scope of the invention as defined in the claims.

Claims (2)

1. Jet device for treating the soil, comprising

   - a string (1) of rods or tubes (2) connected one after another,

   - a device (7,8) for driving the string of rods or tubes in terms of rotation and, if desired, in terms of translation, mounted on the upper part of the said string,

   - at least one ejection nozzle (4,5) provided at the lower part of the said string,

   - at least one source (11,13) of fluid under high pressure, and

   - a supply pipe joining the source of fluid under high pressure to the said nozzle,

   characterized in that :

   - the device for driving the string of rods or tubes imparts an alternating rotational movement to the latter, and

   - the supply pipe joining the said source to the said nozzle consists of a hose (10,12) arranged outside the said string (1).
2. Device according to Claim 1, characterized in that it further includes a pay-out device (14,15) associated with each hose.

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