EP2666911B1 - Method for producing a floor mortar wall in the floor - Google Patents

Description

The invention relates to a method for producing a Bodenmörtelwand in the soil with a drill, which has at least two parallel juxtaposed worms, wherein the at least two endless screws are drilled in the soil while soil material is dissolved, which mixes in the borehole with a binder suspension to the soil mortar which hardens after removing the at least two endless screws in the wellbore to the floor mortar wall.

The invention further relates to a drilling apparatus for carrying out such a method.

Such floor mortar walls are also referred to as sealing walls or enclosing walls, which are used for example in Baugrubenumschließungen or in the rehabilitation of dams.

Such a method is for example from the DE 42 19 150 C1 out. In this known method, one or more augers are introduced into a first region of the soil. After dissolving the soil in this first area liquid binder is supplied, wherein by means of the augers in this first area a soil material-binder mixture is produced. Subsequently, the augers are lowered to a second deeper area and repeats the described process step. These steps are performed until the final depth is reached. The soil mortar mixture is thus produced gradually from above.

Alternatively, in the DE 42 19 150 C1 describes a method in which the auger initially drilled to the final depth and only then the dissolved soil material when retracting the auger with the liquid binder is mixed to the soil mortar. The binder is introduced in the region of the drill bit via a central core tube. In this alternative method, the soil mortar is thus created when pulling the auger from bottom to top.

For the quality of the floor mortar wall as homogeneous a consistency as possible over the entire wall depth is essential. A consistent consistency is important for the tightness and strength of the wall. Depending on the nature of the soil to be processed, especially in very different soil layers, it is often necessary to ensure sufficient homogenization that after creating the soil mortar in the bottom slot, the augers are lowered one or more times in the slot to another by Mixing to achieve a particularly good homogenization. Especially with these final additional strokes floor mortar often occurs to the surface. This means a loss of material and leads to contamination. Ground mortar solidified on the ground is expensive to remove and deposit.

Furthermore, in the DE 102 38 646 B3 described such a method in which juxtaposed wall segments are produced in such a stepwise and overlapping that by the at least partially provided overlap additional homogenization can be effected.

Other methods and drills for making walls in the ground go out of the EP 2 423 388 A1 , of the EP 2 410 092 A1 and the EP 0 663 475 A1 out.

The invention has for its object to provide a method and a drill, with which a floor mortar wall in the soil can be produced in a particularly economical manner and in high quality.

The invention is achieved by a method having the features of claim 1 or by the features of claim 14. Preferred embodiments of the invention are indicated in the dependent claims.

• dass die mindestens zwei Endlosschnecken in einem ersten Schritt bis zu einer Bohrlochtiefe unter Aufbrechen und Lösen des Bodens gebohrt werden, wobei das gelöste Bodenmaterial im Wesentlichen in dem Bohrloch verbleibt,
• dass in einem zweiten Schritt unter Zuführung von Bindemittelsuspension mindestens zwei Endlosschnecken bis zu einer Zwischenposition in dem Bohrloch angehoben werden, wobei zwischen einer Bohrlochsohle und einer Zwischenposition ein unterer Mischbereich gebildet wird, in welchem das gelöste Bodenmaterial mit der zugeführten Bindemittelsuspension zu dem Bodenmörtel vermischt ist,
• dass in einem dritten Schritt die mindestens zwei Endlosschnecken in den unteren Mischbereich abgesenkt werden und
• dass in einem vierten Schritt mindestens eine Endlosschnecke zum Fördern von Bodenmaterial aus dem unteren Mischbereich nach oben und mindestens eine Endlosschnecke zum Fördern von gelöstem Bodenmaterial von einem oberen Bohrlochbereich oberhalb der Zwischenposition in den unteren Mischbereich zumindest solange angetrieben werden, bis Bodenmörtel aus dem unteren Mischbereich bis zur Bodenoberfläche gefördert ist.

The method according to the invention is characterized

• that the at least two endless screws are drilled in a first step to a borehole depth under breaking and loosening of the soil with the dissolved soil material remaining substantially in the borehole,
• in a second step, feeding binder slurry, lifting at least two endless screws to an intermediate position in the wellbore, wherein a bottom mixing region is formed between a bottom hole and an intermediate position, in which the dissolved soil material is mixed with the supplied binder suspension to the soil mortar;
• that in a third step, the at least two endless screws are lowered into the lower mixing area and
• in a fourth step, at least one endless screw for conveying soil material from the lower mixing area upwards and at least one endless screw for conveying dissolved soil material from an upper borehole area above the intermediate position into the lower mixing area are driven at least until bottom mortar reaches from the lower mixing area to is conveyed to the soil surface.

A basic idea of the invention is, after drilling out the endless screws, which are also referred to as augers or augers, to prepare the soil mortar by feeding the binder suspension initially in a lower mixing area only up to an intermediate position of the borehole depth. The augers are thus withdrawn only in part from the well, wherein by supplying the binder in the region of the drill bit a lower mixing area is formed in the slot. This lower mixing area constitutes a reservoir of ready-mixed or substantially ready-mixed floor mortar which, according to the invention, is conveyed upwards into the upper slot area via at least one endless screw. At the same time, soil material from the upper slot area above the intermediate position in the lower mixing area which has been dissolved and not yet mixed is conveyed via at least one other endless screw. The borehole depth reached in the first step is preferably the final depth needed for the traveling position.

Due to the reduced viscosity of the soil mortar in the lower mixing area compared to the soil material in the upper soil area, the added dissolved soil material can be easily and intensively mixed into the soil mortar. The lower mixing zone can be regarded, so to speak, as a reactor zone for producing the floor mortar. It is advantageous that due to a displacement of the mixing in the lower region of the slot leakage of soil mortar and thus contamination of the earth's surface is avoided or at least considerably reduced.

The mixing and conveying of the soil mortar upwards and the downwards conveyance of the not yet mixed, dissolved soil material is continued until the entire dissolved soil material is mixed with binder suspension and distributed over the entire slot. Even when drilling through different soil layers, it is possible to achieve a very homogeneous soil mortar mixture through the borehole depth.

A further significant advantage of the invention is that the endless screws can extend over the entire depth of the well for a long time from the third step, so that the long endless screws their mixing and conveying effect for a relatively long time over the depth of the drill slot exercise. It is thus possible in a relatively short time a good mixing and thus homogenization performance.

In principle, a multiplicity of endless screws can be arranged in line next to each other, wherein the cutting regions of the individual drilling screws adjoin one another. When tuning the screw geometry and certain overlaps of the cutting areas can be provided. It is particularly preferred according to the invention that a drill with three juxtaposed endless screw is used. As a result, a well manageable Bohrschlitzlänge is achieved. The arrangement of four, five or more endless screws is possible.

It is particularly preferred according to the invention that in the fourth step, the two outer endless screws for conveying the soil material in the lower mixing area and the average endless screw for conveying the soil mortar from the lower mixing area are driven upwards. It can be so targeted vertical circulation over the borehole depth can be achieved. By conveying the dissolved soil material more downwards than conveying the soil mortar from the lower mixing area upwards, a particularly thorough mixing is achieved. In addition, it is clearly visible to the operator of the drill when the soil mortar emerges from the upper borehole opening that the soil mortar in the borehole is completely or very largely distributed.

In carrying out the first step, the borehole is created by the augers, but the dissolved and broken soil is not or at least not promoted to a significant extent from the wellbore. During this drilling and sinking of the borehole, depending on the nature of the soil, a liquid supply may be dispensed with. To reduce wear, it is advantageous according to the invention that in the first step in releasing the soil for lubrication binder suspension is fed via at least one core tube of an endless screw. The liquid supply can be introduced via an endless screw, a choice of several endless screws or all continuous screws on the tip or arranged along the Bohrschneckenlänge outlet openings in the dissolved soil material. The addition of liquid, especially the binder suspension, reduces the friction and abrasion on the drilling tools.

A further preferred embodiment of the method according to the invention is that the intermediate position is provided in a lower half of the borehole. Preferably, the lower mixing area extends in the lower quarter or in the lower third of the borehole. The height of the mixing area basically depends on the total depth of the borehole and also on the properties and the particle size distribution of the dissolved soil material.

A good penetration of the endless screws, which have at their front tip Bohrschneiden or teeth is achieved according to the invention in that in the first step, the endless worms are driven depending on a helical direction of the screw helix for screwing into the ground, wherein at certain time intervals, a reversal of direction he follows. By driving in a screwing additionally an axial force is effected by the endless screw, so that thereby the drill is relieved. Unless the augers have the same helical direction, the endless screws would therefore be driven in the same direction. In order to prevent large-scale discharge of soil material from the borehole during such driving in the screwing-in direction, the direction of rotation is reversed at certain times. As a result, soil material can also be partially promoted back into the well. In addition, a short-term reversal of the direction of rotation also promotes the homogenization of the soil mortar.

A good homogenization is achieved according to a further process variant according to the invention in that in the second step, a rotational speed and an axial movement of the endless screw depending on an influx of binder suspension are adjusted so that in the lower mixing area dissolved soil and binder suspension are mixed to the soil mortar , The speeds of the individual endless screws can also be arranged differently from each other. Thus, in particular, the rotational speed of the at least one endless screw for conveying the soil mortar upwards may be greater or smaller than the rotational speed of the at least one endless screw, which is provided for feeding the soil material from above into the lower mixing area.

Further, it is advantageous for a good homogenization of the soil mortar, that before or after the second step, the endless screws are rotationally driven without an axial movement. Especially with axially stationary endless screws and at least partially flowable soil material a good mixing can be achieved.

After lifting the endless screws to the intermediate position they are lowered again in the third step. This lowering can be done up to any position. It is preferred according to the invention that in the third step, the endless screws are lowered to the borehole bottom. Thus, the endless screws extend from the bottom of the hole to the surface. In the subsequent conveying and mixing process, the endless screws can thus have their effect over the entire borehole depth.

A further improvement in the homogenization is achieved in a preferred manner in that in the fourth step, soil mortar conveyed upwards to the soil surface is conveyed again in the direction of the lower mixing area. On the surface, a device, in particular a trench, can be provided, which briefly absorbs outgoing soil mortar for a return conveyance.

It is preferred according to the invention that in the borehole a vertical circulation flow is generated. Depending on the initial condition of the soil material and the desired quality of the desired soil mortar, a circulation from the lower mixing area can be adjusted upwards and back again for a given time via the endless screws. Depending on the direction of rotation of the screw conveyors, upward conveyance can take place in the middle area or through the outer endless screws. The necessary conveying in the opposite direction can then be done by the corresponding other endless screws. The directions of rotation of the endless screw can also be reversed, so that reverses the circulation flow in the slot under a high mixing effect.

According to a further embodiment of the method according to the invention it is provided that in the fourth step, a supply of binder suspension is stopped, while the endless screws are driven to further homogenization of the soil mortar in the borehole further rotating. As stated above, this results in a particularly good mixing effect.

In principle, a single wall segment can be produced in one pass by the method according to the invention. According to the invention, it is advantageously provided that for forming a continuous floor mortar wall a plurality of boreholes are produced side by side. In this case, the individual drill slots can be carried out successively successively or in a so-called pilgrim step method with certain back steps.

There is also provided a floor mortar wall in a floor, the floor mortar wall being formed from a floor mortar mixed from dissolved floor material and a binder suspension. This floor mortar wall is formed in that it is produced according to one of the above-described methods. The binder may in particular comprise cement, cementmilk, bentonite, water and / or other suitable substances which harden with the dissolved soil material to a solid wall mass.

Finally, the invention also includes a drilling device with at least two rotationally driven endless screws for producing a floor mortar wall, wherein at least one endless screw has a central core tube for feeding a binder suspension in a borehole. This drill is according to the invention characterized in that a control is provided for automatically carrying out the method described above. It is an additional advantage that the above-described method is less dependent on the knowledge and experience of the machine operator and thus can be performed automatically. By means of a generally known electronic control, directions of rotation, speeds of rotation and axial feed movements for carrying out the above-described method steps can be entered. A termination of the process can be done automatically or by the operator immediately upon exit of the soil mortar from the borehole or a certain time later.

Fig. 1

eine Seitenansicht eines Bohrgerätes zur Durchführung des erfindungsgemäßen Verfahrens; und

Figuren 2 bis 6

schematische Querschnittsansichten zu einzelnen Verfahrensschritten eines erfindungsgemäßen Verfahrens.

The invention will be further elucidated on the basis of preferred exemplary embodiments, which are shown schematically in the attached drawings. In the drawings show:

Fig. 1

a side view of a drill for carrying out the method according to the invention; and

FIGS. 2 to 6

schematic cross-sectional views of individual process steps of a method according to the invention.

A drill 10 for carrying out the method according to the invention is in Fig. 1 shown. On a carrier device 12, which has a crawler undercarriage and a superstructure rotatably mounted thereon, a mast 14 is arranged via an adjusting device. The mast 14 is formed in the present embodiment as a leader. At a front side of the mast 14, a drilling carriage 16 is slidably guided along the mast 14. The drilling carriage 16 carries the drilling drives 18 for a total of three endless screws 20a, 20b and 20c. Furthermore, a feed device for supplying binder suspension, in particular of liquid cement and bentonite, to the endless screws 20 is provided on the drilling carriage 16. About a pump, not shown, the binder suspension is pumped from a tank on the ground by means of a hose to the drilling carriage 16 upwards.

The endless screws 20 generally have a length between 10 m and 20 m. They each comprise a central core tube 22, on the outside of which helix spirals 24 are provided which extend essentially over the entire length of the core tube 22. The screw flights 24 are designed for conveying material through the borehole depth, with interruptions for mixing elements or connecting yokes 28 being provided. In the illustrated embodiment, a total of three connecting yokes 28a, 28b and 28c are arranged, in which the individual core tubes 22 are each rotatably mounted. The connection yokes 28 connect and stiffen the individual endless screws 20 in order to counteract unwanted deflections of the endless screws 20 in the drilling operation. For this purpose, an oval guide sleeve 30 is provided, which comprises the endless worms 20 and is secured to the lower end of the mast 14.

At the lower end of the endless screws 20, the drill bits 26 are provided. At the drill bit 26 not only a centering tip and substantially radially directed cutting means for cutting the bottom not shown outlet openings for exiting the binder suspension from the hollow core tube 22 are arranged. Between the lower connecting yoke 28c and the drill bits 26, the helices are formed as driving helices 25 whose spiral pitch is greater than the helical pitch of the helical helixes 24. A helical direction on the left-side endless helix 20a is reversed to the helix directions of the other two helical worms 20b and 20c ,

Hereinafter, the operation of the drill 10 and thus the implementation of the method according to the invention is highly schematic in connection with the F igurs 2 to 6 shown and explained. According to Fig. 2 the three endless screws 20, which in the present embodiment all have the same helical direction, driven in rotation and retracted according to the direction of the arrow P1 in the bottom 50.

It will, as of Fig. 3 can be seen, a approximately horizontal cross-section shaped hole 52 created up to a bottom hole 54 in the bottom 50. In this case, soil material 53 is released and comminuted by the endless screws 20. The soil material 53 essentially remains in the created borehole 52. This can be achieved by an occasional reversal of the rotational direction of the endless screws 20. In this construction of the borehole 52, no or only slightly liquid, in particular binder suspension, is supplied.

After reaching the desired depth of the wellbore 52, the endless screw 20 are raised vertically again according to the direction of the arrow P2, wherein according to the direction of the arrow according to Fig. 4 is fed through the core tubes 22 of the endless screw 20 binder suspension 55.

By supplying binder suspension 55 into the lower region of the endless screws 20, a lower mixing region 56 is formed in the borehole 52, in which soil material 53 and fed binder suspension 55 is mixed with the largely finished soil mortar 57. The endless screws 20 are raised to an intermediate position 58 within the wellbore 52. The intermediate position 58 refers to a lower end of the endless screws 20.

After reaching the predetermined intermediate position 58, the endless screw 20 according to the arrows P3 in Fig. 5 lowered back down into the lower mixing area 56. In the illustrated embodiment, now the central endless screw 20b is driven in rotation so that the endless screw 20b floor mortar 57 from the lower mixing area 56 promotes upward according to the arrow P4. At the same time, the two outer endless screws 20a, 20c are driven in rotation such that they convey ground material 53 released from an upper borehole area 59 above the intermediate position 58 downward into the lower mixing area 56 in accordance with the arrows P5. In the lower mixing region 56 finished soil mortar 57 is prepared by further supply of liquid binder suspension from the supplied soil material 53. Overall, results from the set material flow according to the arrows P4 and P5 a material cycle between the lower mixing area 56 and the upper borehole area 59. This material circulation in the borehole 52 is maintained until at least until soil mortar 57 has reached a bottom surface 51 and the entire borehole 52 is filled with the ready mixed soil mortar 57, as in FIG Fig. 6 is shown. After completion of the soil mortar in the entire borehole 52, the endless screws 20 can be withdrawn from the borehole 52 again. The soil mortar 57 in the wellbore 52 may then harden to the soil mortar wall 60.

Claims (14)

1. Method for producing a soil mortar wall (60) in the soil (50) with a drilling apparatus (10) having at least two continuous flight augers (20) arranged in parallel next to each other, wherein the at least two continuous flight augers (20) are drilled into the soil (50) and soil material (53) is loosened thereby which is mixed in the borehole (52) with a binder suspension (55) to a soil mortar (57) which, following removal of the at least two continuous flight augers (20), hardens to the soil mortar wall (60) in the borehole (52),
   characterized in that

   - in a first step the at least two continuous flight augers (20) are drilled up to a borehole depth whilst breaking up and loosening the soil (50), wherein the loosened soil material (54) substantially remains in the borehole (52),

   - in a second step the at least two continuous flight augers (20) are raised up to an intermediate position (58) in the borehole (52) whilst binder suspension (55) is being supplied, wherein between a borehole bottom (54) and the intermediate position (58) a lower mixing area (56) is formed, in which the loosened soil material (53) is mixed with the supplied binder suspension (55) to the soil mortar (57),

   - in a third step the at least two continuous flight augers (20) are lowered into the lower mixing area (56) and

   - in that in a fourth step at least one continuous flight auger (20b) serving to convey soil material (53) from the lower mixing area (56) in the upward direction and at least one continuous flight auger (20a, 20c) serving to convey loosened soil material (53) from an upper borehole area (59) above the intermediate position (58) into the lower mixing area (56) are driven for at least so long until soil mortar (57) is conveyed from the lower mixing area (56) up to the soil surface (51).
2. Method according to claim 1,
   characterized in that
   a drilling apparatus (10) with three continuous flight augers (20) arranged next to each other is used.
3. Method according to claim 2,
   characterized in that
   in the fourth step the two outer continuous flight augers (20a, 20c) are driven to convey the soil material (53) into the lower mixing area (56) and the central continuous flight auger (20b) is driven to convey the soil mortar (57) from the lower mixing area (56) in the upward direction.
4. Method according to any one of claims 1 to 3,
   characterized in that
   in the first step during loosening of the soil (50) binder suspension (55) is supplied for the purpose of lubrication via at least one hollow stem (22) of a continuous flight auger (20).
5. Method according to any one of claims 1 to 4,
   characterized in that
   the intermediate position (58) is provided in a lower half of the borehole (52).
6. Method according to any one of claims 1 to 5,
   characterized in that
   in the first step, depending on a flight direction of the auger flights (24), the continuous flight augers (20) are driven so as to be screwed into the soil (50), wherein a reversal of the direction of rotation takes place at specific time intervals.
7. Method according to any one of claims 1 to 6,
   characterized in that
   in the second step a rotational speed and an axial movement of the continuous flights augers (20) are set depending on an inflow of binder suspension (55) so that in the lower mixing area (56) loosened soil material (53) and binder suspension (55) are readily mixed to the soil mortar (57).
8. Method according to any one of claims 1 to 7,
   characterized in that
   before or after the second step the continuous flight augers (20) are driven in a rotating manner without axial movement.
9. Method according to any one of claims 1 to 8,
   characterized in that
   in the third step the continuous flight augers (20) are lowered up to the borehole bottom (54).
10. Method according to any one of claims 1 to 9,
    characterized in that
    in the fourth step soil mortar (57) conveyed upwards to the soil surface (51) is conveyed back towards the lower mixing area (56).
11. Method according to any one of claims 1 to 10,
    characterized in that
    in the borehole (52) a vertical circulatory flow is generated.
12. Method according to any one of claims 1 to 11,
    characterized in that
    in the fourth step a supply of binder suspension (55) is stopped while the continuous flight augers (20) continue to be driven in a rotating manner for further homogenization of the soil mortar (57) in the borehole (52).
13. Method according to any one of claims 1 to 12,
    characterized in that
    to form a continuous soil mortar wall (60) several boreholes (52) are produced next to each other.
14. Drilling apparatus having at least two continuous flight augers (20) driven in a rotating manner for producing a soil mortar wall (60), wherein at least one continuous flight auger (20) has a central hollow stem (22) for supplying a binder suspension (55) to a borehole (52),
    characterized in that
    a control for automatically implementing a method according to any one of claims 1 to 13 is provided.

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