EP1069245B1 - Process of improving ground by means of lime columns - Google Patents

Abstract

The method involves supplying a dry binder through a sink pipe (11) sunk into the ground. The sink pipe has a cylindrical cladding pipe (12), an inner pipe (13) and a flap (17) at its lower end. The sink pipe is driven vertically into the ground to a predetermined depth, with the flap closed. The inside of the cladding pipe is supplied with dry binder, and at the same time air is drawn from the lower end of the pipe up through the inner pipe. After the cladding pipe has been filled to a partial height with dry binder, the sink pipe is drawn from the ground with the flap open, while further binder is supplied, so that a column of dry binder is left in the ground. An Independent claim is included for a device for implementing the method.

Description

The invention relates to a method for soil improvement by introducing a dry binder over a lowering tube that has been lowered into the ground cylindrical jacket tube and a flap located at the lower end of the jacket tube having. Furthermore, the invention relates to a device for performing this Process.

Various methods of soil improvement are known in which the binders from injection pipes driven into the ground at different depths be injected into the ground. There are also processes for the manufacture of in-situ concrete piles known, one with a closed flap below Empty sink pipe driven into the ground filled with concrete and then under Generating the in-situ concrete pile with the flap open. You can do this on the CH-PS 538 573 and refer to DE 41 37 541 A1.

EP 0 903 440 A2 describes a method and a device for soil improvement known by means of powdery binder. After that, the binder is added Overpressure is blown into a lock tube via a feed tank the upper end of the lock tube is arranged. At the bottom of the lock tube, where a vibrator is arranged, the binder emerges from the lock tube out. The compressed air used to blow in the binder is over the Blown off the feed container, i.e. in front of the lock tube, which causes the air flow is low in the lock tube.

DE 41 25 576 A1 describes a method for pressing powder into soft Soils known, in which the powder initially with an increased air pore volume provided and then pressed into the ground by means of compressed air through thin pipes becomes. The discharge of the compressed air is not discussed.

The present invention is based on the object of a method for soil improvement to provide with both bulk and grown Soil formations can be sustainably improved. The solution is a procedure in the following sequence of steps: the lowering tube is closed Flap driven vertically into the ground to a predetermined depth The dry binder is fed inside the jacket tube after filling of the casing pipe up to a part height with dry binding agent becomes the lowering pipe when the flap opens while continuing to add dry binder pulled out of the ground, creating a column of dry binder in the ground, wherein the dry binder with compressed air as a carrier medium in the jacket tube is blown while at the same time air from the lower end of the casing tube exits in this longitudinal inner tube. Filling the casing tube in particular takes place up to half its height before it is pulled. The air can be sucked out of the jacket tube via the inner tube, as long as the binder is in a fluidized, highly air-enriched state located.

The device according to the invention comprises a countersunk tube consisting of a cylindrical Jacket tube and one arranged at the lower end of the jacket tube Flap, in which the casing tube at its upper end with a device for Promotion of the dry binder is connected and a compressed air generator or a blower for conveying the dry binder with compressed air as the carrier medium is provided in the jacket tube and an inner tube extending longitudinally in this ends freely in the casing tube with its lower end and out with its upper end emerges from the casing tube and is connected to the environment. The inner tube can especially with a suction fan for extracting air from the jacket tube be connected.

When using the method according to the invention, it is provided in particular that that in advance a grid pattern with a grid dimension of in particular 15 to 100 cm is marked on the floor surface, in which each grid point the position of a Column determined. The outer diameter of the casing tube corresponds essentially the final diameter of the individual column, in particular 100 to 200 mm. After a grid pattern has been applied to the floor surface in advance the following procedural actions are carried out at each grid point. The lowering tube with the closed flap is made using known handling devices pressed, shaken or hammered into the ground until its lower End has reached the required depth, with the upper end still over the Floor surface protrudes. When the final depth is reached, dry binder introduced into the jacket tube, air escaping through the inner tube at the same time can or is suctioned off. The dry binder can be introduced with a suitable pump or with a blower, in which compressed air is then used as a carrier medium acts, take place. The compressed air can also be pulsed here. About the The compressed air should be released from the inner tube or, if necessary, for compression of the dry binder are sucked off, with the simultaneous sucking of binders should be avoided to a significant extent. Is the casing tube at least up to a partial height, for example half full, it gets slow pulled upwards out of the floor, the flap automatically opening or forced opening and the dry binder is relatively low as a column Diameter remains in the ground. After that, the device is moved to another Move the grid point of the grid and the process is repeated. It is particularly advantageous if lime and / or cement is used as the dry binder becomes.

• auf einer Reaktion der Hydratation (Bildung von Ca (HO2)), die sehr exotherm sein kann und sich in einer Verminderung des Wassergehaltes des Bodens auswirkt;
• einer Veränderung der geotechnischen Eigenschaften des Bodens durch Anlagerung von Ca-lonen und Ausflockung von Tonpartikeln, die sich in einer Erhöhung des Scherwiderstandes und einer Verminderung der Kompressibilität auswirken;
• einer Veränderung der Struktur des Tons durch die Bildung von Aluminaten und Silikaten von Kalciumhydraten.

The mode of action of the columns made of lime and / or cement, ie columns made of dry hydraulic binders, is in the case of the non-extinguished lime CaO

• a reaction of hydration (formation of Ca (HO2)), which can be very exothermic and results in a reduction in the water content of the soil;
• a change in the geotechnical properties of the soil due to the accumulation of calcium ions and flocculation of clay particles, which result in an increase in shear resistance and a decrease in compressibility;
• a change in the structure of the clay due to the formation of aluminates and silicates of calcium hydrates.

When using cement, the effects are less pronounced, but here is the reaction in the presence of Water much faster. To combine both effects can be worked with mixtures of lime and cement.

The effect of the sink tube has several aspects, namely that Displacing the floor to form a cavity when pressed in of the sink pipe, then the entry of lime or cement into the cavity with simultaneous provisional piping of the cavity in the floor and finally the formation of the column made of binders in the ground when pulling the counterbore.

The lowering tube can be pulled continuously or in steps done at a predetermined speed, the Speed of pulling the speed of the if applicable adapted continued tracking of binder must become.

The lowering tube is usually attached to the leader of a crawler vehicle attached, the guide carriage provided with driving agents are.

The machine operator of the crawler vehicle can adjust the inclination of the Leader, the depth of driving in and the volume flow of added Monitor and control lime or cement.

Fig. 1

zeigt ein erfindungsgemäßes Senkrohr im Vertikalschnitt;

Fig. 2

zeigt eine erste Phase des erfindungsgemäßen Verfahrens;

Fig. 3

zeigt

a) eine zweite Phase,

b) eine dritte Phase,

c) eine vierte Phase

des erfindungsgemäßen Verfahrens jeweils mit einem Raupenfahrzeug mit Mäkler;

Fig. 4

zeigt Anlagenteile der erfindungsgemäßen Vorrichtung.

The invention is explained below with reference to the accompanying drawings.

Fig. 1

shows a countersunk pipe according to the invention in vertical section;

Fig. 2

shows a first phase of the method according to the invention;

Fig. 3

shows

a) a second phase,

b) a third phase,

c) a fourth phase

of the method according to the invention each with a caterpillar with leader;

Fig. 4

shows plant parts of the device according to the invention.

In Figure 1, a counterbore 11 according to the invention is shown in a vertical, user-friendly position. This comprises a cylindrical jacket tube 12 and an inner tube 13 of smaller diameter running longitudinally therein, which is open at the bottom and ends freely at a smaller distance from the end of the jacket tube 12. Means for holding the inner tube 13 in the casing tube 12 are not shown here for simplicity. The lowering tube 11 has a head piece 14 at the upper end, which is used to engage a driving device. Below the head piece 14, the casing tube 12 has a first lateral connection 15, through which dry binder is blown into the casing tube. The inner tube 13 has at the upper end below the head piece 14 a bend 16 which passes through the wall of the jacket tube and from which displaced air can escape from the jacket tube 12, or air can be sucked out of the inner tube 13 and thus from the jacket tube 12, as indicated by symbols. At the lower end, the casing pipe has a flap 17 which can close the casing pipe when it is driven into the ground, while it can open automatically when the sink pipe is pulled out of the ground, so that a flow of the dry binder, which is indicated by an arrow 18 , can emerge from the casing tube. The outer diameter of the casing tube is marked with d _m .

In FIG. 2, a perspective view of a section of a floor surface is symbolized, on which a grid grid 21 is shown, the crossing points of which are spaced apart from one another in two directions perpendicular to one another by the same unit distance a. Completed columns 22 are visible on part of the grid points, two of which are shown in vertical section; these have column diameters d _s .

In Figure 3 is a vertical section through an upper layer of soil shown. There is a caterpillar vehicle on the ground surface 31 32 on. This has a vertically positioned leader 33 with a slide 34. A lowering tube 11 is on the slide 34 attached, which has already been described previously. To the caterpillar leads a hose 35, which to the top End of the counterbore 11 leads.

In Figure 3a, five completed columns 22 can be seen. To form another column, the lowering tube is just in the Grid spaced in or rammed in, as by a vertical arrow is shown.

Another arrow indicates the general direction of work progress of the crawler vehicle indicated.

In Figure 3b, the countersink tube 11 is pressed to the bottom or struck, in which the finished columns 22 end. In This position starts the next phase of work by using the Line 35 is now blown dry binder into the counterbore will, while air comes out at the top can.

In Figure 3c is the next phase of column manufacture shown shortly before graduation. The lowering tube 11 is as through indicated an arrow, largely pulled out of the ground. at open flap at the lower end of the countersunk tube is due to flowing out the dry binder another column 22 almost completed.

In Figure 4 are the device units for supplying the line 35 shown. Specifically, there is a silo 41 for dry binder shown from which via a screw conveyor 42 Drive motor 43 binder in a hopper 44 one Dosing pump 45 is abandoned. At the metering pump 45 is a Compressed air compressor 46 connected, the compressed air as a carrier medium generated for the binder, which is then via the line 35 is promoted to the lowering tube.

Claims (10)

1. A method of improving the soil by introducing a dry bonding agent through a lowering pipe (11) which had previously been lowered into the soil and which comprises a cylindrical jacket pipe (12) and a flap (17) arranged at the lower end of the jacket pipe, comprising the following sequence of stages:

   the lowering pipe, with its flap in a closed condition, is driven vertically into the soil down to a predetermined depth;

   the dry bonding agent is fed into the jacket pipe;

   after the jacket pipe has been filled with the dry bonding agent up to part of its height, the lowering pipe, with the flap being in an open condition, is lifted out of the soil, with further bonding agent being introduced, wherein the dry bonding agent is blown into the jacket pipe by compressed air serving as a carrier medium,

   characterised in that, while the bonding agent is being blown in, air simultaneously leaves the lower end of the jacket pipe through an inner pipe (13) extending longitudinally in said jacket pipe, and enters the environment.
2. A method according to claim 1,
   characterised in that the jacket pi pe is filled up to at least half its height before it is lifted.
3. A method according to any one of claims 1 and 2,
   characterised in that air is extracted from the jacket pipe through the inner pipe.
4. A method according to any one of claims 1 to 3,
   characterised in that, first, a lattice grid is marked on the soil surface in which each grid point determines the position of a column.
5. A method according to claim 4,
   characterised in that the grid lines are marked at identical distances from one another, ranging between 15 and 100 cm.
6. A method according to any one of claims 1 to 5,
   characterised in that the columns are produced with a diameter of 100 to 200 mm.
7. A method according to any one of claims 1 to 6,
   characterised in that the dry bonding agent is lime or cement or mixtures thereof.
8. A device for improving soil by introducing a bonding agent, comprising a lowering pipe (11) which comprises a cylindrical jacket pipe (12) and a flap (17) arranged at the lower end of the jacket pipe, wherein the jacket pipe, at it upper end, is connected to a device (15) for conveying the dry bonding agent, wherein there is provided a compressed air generator (45) or a blower for conveying the dry bonding agent into the jacket pipe, using compressed air as the carrier medium,
   characterised in that an inner pipe (13) longitudinally extending in the jacket pipe, with its lower end, ends freely in the jacket pipe and, with its upper end, leaves the jacket pipe and is connected to the environment.
9. A device according to claim 8,
   characterised in that a suction blower for extracting air from the jacket pipe is connected to the upper end of the inner pipe.
10. A device according to any one of claims 8 or 9,
    characterised in that the lowering pipe is secured to a leader (33) of a tracked vehicle (32).

Images