EP3094787B1 - Ground anchor - Google Patents

Description

The invention relates to a stranded pressure tube anchor according to the preamble of claim 1.

Geotechnical anchors, which include the generic Litzdruckanker are used, inter alia, in construction projects to secure the side walls of the pit, for example, by back-anchored security walls against collapse. An anchor of this type is in particular from the document WO 2007/066860 A1 known. In this case, the pressure forces which are exerted by the security walls immediately adjacent ground on the security walls, delivered via several geotechnical anchor to the more distant ground. Since the anchors protrude especially in construction projects in the inner city area in the subsurface of the neighboring property and can hamper future construction projects, the use of geotechnical anchors is increasingly subject to the requirement that after completion of the construction no parts or only steel parts with limited dimensions remain in the ground allowed to.

Basically, two types of anchors are to be distinguished, depending on the construction of the tension elements, namely on the one hand, the rod anchor, in which the tension member is formed by a rigid steel rod, and on the other the strand anchor, in which the tension member is formed by a steel strand. Strand anchors have the advantage over bar anchors that they are cheaper to produce at the same carrying capacity. In addition, they can be supplied wound up, which means that without anchors mounted on site larger anchor lengths are possible than with bar anchors whose maximum delivery length is usually limited to 18 m.

Furthermore, a distinction is made depending on the type of initiation of the armature clamping forces in the surrounding ground between composite anchors and pressure pipe anchors:

In the case of the composite anchor, the tension element connecting the securing wall to the anchor base element is embedded in the compression body, which is usually formed of hardened cement, at least over part of its length, the so-called injection length. In the area of the free anchor length, the bond between the tension element and the surrounding cement is interrupted, for example by a jacket by means of a plastic tube. Therefore, the clamping force of the tension element is constant here and then decreases continuously within the Verpresskörpers from the beginning of the injection length to the anchor base element. The armature clamping forces in this case transferred mainly via tensile stress of the grout to the surrounding ground.

Composite anchors are customarily only partially expandable. And although only the free anchor length corresponding length section can be removed again, while you the Verpresslänge corresponding length section remains in the underground. The predetermined breaking point between the two length sections can be provided, for example, in the context of producing the anchor strand by inductive heating of the transition region between the two longitudinal sections. As a result, but also decreases the overall load capacity of the anchor strand. There are also solutions in which the anchor strand is weakened by heating only in the course of rebuilding. The necessary elements, such as cables and heating elements must be installed in this case but already in the production, which makes the construction complex and expensive. For mechanical weaknesses provided during production, this applies analogously to the statements made by inductive heating.

A not to be underestimated problem is that the anchor strands must be placed under tension during removal to the predetermined breaking point to break. If the predetermined breaking point breaks, this tensile stress is instantaneously broken down, which frequently leads to the anchor stranding out of the anchoring hole. It is easy to see that this is associated with a considerable risk of injury to the personnel developing the anchor strands. An attempt is made to minimize this risk by costly and expensive measures, such as safety nets. However, it can not be completely ruled out.

For fully removable composite anchors, the grout area must be destroyed before rebuilding the anchor line. This can be done, for example, by the detonation of an explosive charge, by the application of a transverse tensile stress by means of a strand provided separately for this purpose, or by means of liquid jets ejected from high-pressure nozzles. However, all of these measures require separate provisions that complicate the construction of the composite anchor.

In the pressure tube anchor, however, the tension element is surrounded along the entire anchor length by a cladding tube, which protects the tension element from direct contact with the pressing body formed from hardened cement mortar. In the pressure tube anchor, the tensioning force of the tension element, which runs constantly up to the anchor base element, is completely transmitted to the anchor base element over a short connection length. From there it is then, if necessary, supported by a cooperating with the anchor base element pressure tube, transmitted via compressive stress of the grout to the surrounding ground.

From the WO 2002/077373 A1 is a generic, fully expandable strand pressure anchor known. Armature tension forces are transferred from the strand to the armature base element with the aid of several wedge elements. The wedge elements are in holding engagement with the surface of the strand via a toothing, which is maintained as a result of the tensile stress of the strand by the interaction of the wedge surfaces of the wedge elements with counter wedge surfaces of the anchor base element. Furthermore, from the WO 2002/077373 A1 known stranded pressure tube anchor on a substantially T-shaped element which is on the one hand over the crossbar of the T-shape with the ends of the wedge elements in driving engagement. On the other hand, the base web of the T-shape on an external thread, which is intended to cooperate with a counter-thread formed in a recess of the anchor base member.

To remove the strand after the use of the stranded pressure tube anchor, the procedure is as follows: First, the engagement between the wedge elements and the wedge surfaces of the anchor base element is released by compressive stress of the strand. Then the strand is completely inserted into the anchor base element. It takes over the wedge elements with the T-shaped element, until it rests against the opening of the threaded recess of the anchor base member. Subsequently, the T-shaped element is screwed by turning the strand and entrainment of the wedge elements in the threaded recess. The entrainment of the wedge elements triggers the contact between the strand and wedge segments, whereby the strand can be pulled out of the anchor base element and thus out of the entire borehole.

As you can easily see, there is a first disadvantage of the WO 2002/077373 A1 known construction in that the release of the wedge elements decides on the possibility of complete removal of the strands. Especially with long strand anchors associated with high preload forces can cause the release by applying a compressive load problems. In order to be able to easily detach the wedge elements, their surface must be hardened accordingly or the degree of utilization of the strands must be limited. In addition, the required from the WO 2002/077373 A1 known construction the use of a large number of components. Thus, in addition to the provision of the wedge elements and the substantially T-shaped element, the anchor base element must be formed in two pieces, in order to be able to provide the wedge surfaces and the threaded recess for another.

Object of the present invention is to provide a generic stranded pressure tube anchor, which has a simpler structure and also can be particularly easily and quickly removed.

This object is achieved by a completely removable stranded pressure tube anchor of the generic type, in which the Zuglitze or at least one of the tension strands is provided at its the pressure anchor base element associated end with a compression sleeve, which is provided with an external thread, which in a connected Condition of drawstring and pressure anchor base member, in which the drawstring is connected to the pressure anchor base member for forwarding the anchoring forces to the surrounding ground, is in threaded engagement with an internal thread of the pressure anchor base member. Preferably, all pull strands are screwed to the pressure anchor base member via a male threaded compression sleeve.

According to the invention, only one additional element is required per completely removable towed strand, namely the compression sleeve provided with the external thread. This is bolted directly to the pressure anchor base element. Therefore, the pull cord can be unscrewed after use in a simple manner again from the pressure anchor base member. It is advantageous if the direction of impact of the pull cord is equal to the direction of rotation of the thread of the arranged at its free end of the compression sleeve. If the compression sleeve is provided with a right-handed thread, ie a thread which is designed to rotate in a clockwise direction when viewed in the screwing-in direction in order to screw it into the pressure anchor base element, then the wires from which the strand is formed also run is towards the compression sleeve with a legal blow. Due to the similarity of compression sleeve thread and Litzenschlagrichtung the pull cord pulls together when unscrewing, so that the wires of the strand do not open, but are stronger against each other and support each other. The strand is characterized torsionally rigid over its entire length and can then in a simple manner from the Pressure anchor Basiselenient be unscrewed when attacked only at its remote from the pressure anchor base element end.

The cladding tube can not only be used to prevent complete embedding of the pull cord into the grout material. Rather, the cladding tube can also be used to protect the screw from a, in particular festsetzenden, influence of the grouting material. For this purpose, it is advantageous if the cladding tube or at least one of the cladding tubes is sealingly connected to the pressure anchor base element. In this way, the penetration of the material used for the pressing, in particular cement, can be prevented in order not to hinder the unscrewing of the tension strands.

By way of example, the pressure anchor base element can have, on its surface facing the tension strand or of the plurality of tension strands, a recess for the cladding tube or at least one of the cladding tubes, into which the free end of an associated cladding tube can be inserted. By this insertion, a kind of labyrinth sealing effect can already be produced, which protects the screw connection from the penetration of the material used for the pressing. This sealing effect can be enhanced by the fact that the cladding tube is arranged in the recess in the press fit.

Additionally or alternatively, it can be provided that the cladding tube is screwed to the pressure anchor base element. For example, the cladding tube can be screwed into the recess of the pressure anchor base element. In principle, however, it is also possible that the cladding tube is screwed to the pressure anchor base element via separate sealing means.

For a further constructive simplification of the stranded pressure tube anchor according to the invention, it is proposed that when a plurality of tension strands is provided, at least one tension strand, preferably all tension strands, is assigned a separate cladding tube. By not each Zuglitze a separate cladding tube is assigned, the number of for the construction The components required for the stranded pressure tube anchor according to the invention can be further reduced.

As is known per se from pressure pipe anchors, the stranded pressure-tube anchor according to the invention may also comprise at least one pressure body which cooperates with the pressure-anchor base element in passing on the anchoring forces to the surrounding ground. This pressure body can surround the tension strand or the plurality of tension strands and, for the effective transmission of the pressure forces, bear against the pressure anchor base element or a further pressure body, preferably flat, with an end face facing the pressure anchor base element.

On its outer circumferential surface, the pressure body may have at least one recess running essentially parallel to the longitudinal extension direction of the tension cord or of the plurality of tension strands. In such a recess, for example, a supply line for supplying injection material can be inserted.

Furthermore, a plurality of circumferentially extending ribs can be provided on the outside of the pressure body, which can improve the grip in the surrounding ground.

In addition, in the circumferential direction, where a passage opening intended for passage of the pull cord or one of the pull strands extends radially outwards, the pressure body can be designed to be free from ribs extending in the circumferential direction. The or the pressure body remains or remain after the removal of the tension strands together with pressure anchor base element in the underground. During construction work in this subsoil, the pressure hull, for example, from an excavator bucket or a tunnel boring machine, should be easily broken. This is facilitated by the inventively provided predetermined breaking points, which are formed by those circumferential positions, which are free from the circumferentially extending ribs. Favorable for this is also the Production of the pressure body of a brittle material, such as cast iron, concrete, mortar, glass, ceramics or the like, since this relatively easily breaks.

It should also be added that it is advantageous if the cladding tube is dimensioned and / or configured at least at its end portion adjacent to the pressure anchor base element such that the external thread of the compression sleeve of the associated pull cord alone when inserted into the cladding tube connected to the pressure anchor base member alone the insertion movement of the pull cord is inserted into the internal thread of the pressure anchor base element. In this way, if you want to solve the pull cord for some reason again from the pressure anchor base element, not also the associated cladding of the pressure anchor base element to solve, and can be sure that the screw engagement between the external thread of the compression sleeve of the associated Zuglitze and the internal thread of the pressure anchor base element can be easily restored. For example, the cladding tube may be formed at its end portion adjacent to the pressure anchor base element with insertion bevels. However, it is also conceivable that the clearance between cladding tube and compression sleeve is dimensioned such that it is less than twice the difference between the nominal diameter and the core diameter of the external thread of the compression sleeve, preferably less than this difference.

Figur 1

eine teilweise geschnittene perspektivische Ansicht einer ersten Ausführungsform eines erfindungsgemäßen Litzen-Druckrohrankers, welcher drei Litzen umfasst;

Figur 2

eine Seitenansicht des Litzen-Druckrohrankers der Figur 1;

Figur 3

eine längs den Linien III-III, d.h. im Bereich eines Druckkörpers, genommene Schnittansicht des Litzen-Druckrohrankers der Figuren 1 und 2;

Figur 4

eine längs den Linien IV-IV, d.h. im Bereich der Fußbox, genommene Schnittansicht des Litzen-Druckrohrankers der Figuren 1 und 2;

Figur 5

eine längs den Linien V-V genommene Schnittansicht der Fußbox der Figur 4;

Figur 6

eine perspektivische Ansicht eines Druckkörpers;

Figur 7

einen Längsschnitt durch den Grundkörper einer Presshülse;

Figur 8

einen Längsschnitt durch eine Einsatzhülse, die in den Grundkörper eingesetzt zusammen mit diesem die Presshülse bildet;

Figur 9

eine Darstellung zur Erläuterung des Einführens einer Litze in die Presshülse;

Figur 10

eine Darstellung zur Erläuterung des Aufpressens der Presshülse auf die Litze;

Figuren 11 bis 13

Ansichten ähnlich Figuren 1 bis 3 einer zweiten Ausführungsform eines erfindungsgemäßen Litzen-Druckrohrankers, welcher vier Litzen umfasst;

Figuren 14 bis 16

Ansichten ähnlich Figuren 1 bis 3 einer zweiten Ausführungsform eines erfindungsgemäßen Litzen-Druckrohrankers, welcher sieben Litzen umfasst;

The invention will be explained in more detail below with reference to embodiments with reference to the accompanying drawings. It shows:

FIG. 1

a partially cutaway perspective view of a first embodiment of a stranded pressure tube anchor according to the invention comprising three strands;

FIG. 2

a side view of the strand pressure tube anchor the FIG. 1 ;

FIG. 3

a taken along the lines III-III, ie in the region of a pressure hull, taken sectional view of the strand pressure-tube anchor of Figures 1 and 2 ;

FIG. 4

a along the lines IV-IV, ie in the footbox, taken sectional view of the strand pressure-tube anchor of Figures 1 and 2 ;

FIG. 5

a taken along the lines VV sectional view of the Fußbox the FIG. 4 ;

FIG. 6

a perspective view of a pressure hull;

FIG. 7

a longitudinal section through the main body of a compression sleeve;

FIG. 8

a longitudinal section through an insert sleeve which is inserted into the body together with this forms the compression sleeve;

FIG. 9

a representation for explaining the insertion of a strand in the compression sleeve;

FIG. 10

a representation for explaining the pressing of the compression sleeve on the strand;

FIGS. 11 to 13

Similar views FIGS. 1 to 3 a second embodiment of a stranded pressure tube anchor according to the invention, which comprises four strands;

FIGS. 14 to 16

Similar views FIGS. 1 to 3 a second embodiment of a stranded pressure tube anchor according to the invention, which comprises seven strands;

In the Figures 1 and 2 a stranded pressure tube anchor according to the invention is generally designated 10. It comprises a Fußbox 12, which forms the pressure anchor base element according to the invention, three strands 14 which are fixed by means of compression sleeves 16 in the Fußbox 12, three sheaths 18, each of which surrounds one of the strands 14, and pressure hull 20 to which the Fußbox 12 forwards the tensile forces transmitted to them by the strands 14 as compressive forces.

How to especially the synopsis of FIGS. 4 and 5 For each of the three strands 14, the foot box 12 has a stepped receiving bore 22 with a smaller diameter portion 24 disposed deeper in the foot box and provided with an internal thread 24a and a larger diameter portion 26 of the surface 12a the foot box 12 is arranged adjacent and also provided with an internal thread 26a. The smaller diameter portion 24 serves to secure the ferrule 14 pressed onto the associated strand 14 and provided with an external thread 16a, while the larger diameter portion 26 serves to secure the cladding tube 18 surrounding the associated strand.

For example, for producing the stranded pressure-tube anchor 10 according to the invention, the following procedure can be adopted:

In a first step, the compression sleeves 16 are pressed onto the associated strands 14. Each compression sleeve 16 comprises a body 28 made of a deformable material, such as blank, free-cutting or tempering steel (see FIG. 7 ) and an insert sleeve 30, which ensures the secure fit of the main body 28 on the strand 14. The insert sleeve 30 is formed for this purpose both on its inside and on its outside in each case with a toothing. When pressing the compression sleeve 16 on the strand 14 dig these two teeth on the one hand in the material of the body 28 and on the other hand in the material of the Strand 14. Furthermore, the insert sleeve 30 may be formed as a longitudinally slotted sleeve, so that they can invest when pressing the compression sleeve 16 on the strand 14 fully against the outer surface of the strand 14 without even experiencing a significant plastic deformation. The insert sleeve 30 may be made for example of blank, automatic or tempered steel.

For pressing the press sleeves 16 on the associated strands 14, the insert sleeves 30 are first in FIG. 7 introduced from the left into the main body 28. This is facilitated by an insertion bevel 28a. Subsequently, the thus formed compression sleeve 16 in FIG. 9 attached from the left to the associated strand 14 until the strand 14 protrudes slightly on the other side, for example between about 5 mm and about 10 mm, from the compression sleeve 16. Hereupon, the actual pressing on can take place by plastic deformation of the main body 28. Here, the base body 28, as you can compare the FIGS. 9 and 10 decreases, both reduced in its outer diameter and somewhat elongated. Finally, in the outer peripheral surface of the main body 28 of the compression sleeve 16, the external thread 16a is cut.

In a second step, the thus prepared strands 14 are inserted into the associated sheaths 18. Advantageously, the cladding tubes 18, which are preferably made of plastic, for example polyethylene (PE), are also provided with an external thread 18a at that end from which the pressing sleeves 16 protrude.

In a third step, the desired number of strands 14, in the present embodiment, three strands 14, summarized, and the required number of pressure bodies 20 is pushed onto the strands 14.

Then, the strands 14 are successively brought to the Fußbox 12 for mounting the strands 14. For fastening a stranded wire 14 in the foot box 12 the pressed on the strand 14 compression sleeve 16 is screwed with its external thread 16a in the internal thread 24a of the portion 24 of smaller diameter. Subsequently, the cladding tube 18 is screwed with its external thread 18a in the internal thread 26a of the portion 26 of larger diameter, resulting in a sealing engagement between Fußbox 12 and cladding tube 18, in particular a sealing against the ingress of cement mortar engagement.

According to an alternative embodiment could be dispensed with in the Fußbox 12 on the formation of the internal thread 26a in the section 26 of larger diameter and on the cladding tube 18 on the formation of the external thread 18a. The sealing engagement between Fußbox 12 and cladding tube 18 could be ensured in this case by a press fit between Fußbox 12 and cladding tube 18.

Now, the pressure body 20 are still pushed to the Fußbox 12 until they rest against the end face of this or the respectively adjacent pressure body 20 for later transmission of compressive forces. This condition is secured by a securing unit 32, for example an adhesive tape, a heat-shrinkable tube, an electrofusion socket or the like. This securing unit 32 may also have the task of preventing or at least hindering the penetration of cement mortar between the ducts 18 and the pressure body 20.

In the condition thus obtained, the stranded pressure tube anchor 10 is ready for insertion and anchoring in the borehole provided on site.

The removable stranded pressure tube anchors 10 are factory pre-assembled, wound up and delivered to the site. After drilling, the pre-fabricated anchors can be inserted immediately into the borehole. In principle, it is also conceivable to assemble the stranded pressure tube anchors on the construction site. The factory pre-assembly has the advantage to avoid additional on-site work that could hinder site traffic.

When the stranded pressure anchor 10 has been inserted into the drilled wellbore that is typically buried in the earth, it must next be affixed to it, for example by means of cement mortar. In order to be sure that the foot box 12 and the pressure bodies 20 are completely embedded in cement mortar, the pressure bodies 20 are best placed in the Figures 3 and 5 recognizes formed with longitudinal recesses 20a, in the (not shown) supply lines for cement mortar can be inserted. If desired, these longitudinal recesses can also continue in the outer circumferential surface of the foot box 12, as can be seen in FIG FIG. 1 recognizes. Further, the pressure bodies 20 are formed with circumferential ribs 20b, which serve to better anchor the pressure body 20 in the cement mortar.

If the cement mortar has cured, then the stranded pressure-tube anchor 10 can be braced to secure the excavation with a safety wall provided for this purpose. When pressed with cement mortar, the cladding tubes 18 and their sealing engagement with the foot box 12 ensure that the strands 14 do not come in contact with the cement mortar. The applied to the strands 14 serving as tension elements tensile forces are therefore completely transferred to the Fußbox 12, which forwards them via their end face 12a as compressive forces to the pressure body 20. From the foot box 12 and the pressure bodies 20, the forces are then transmitted via the so-called injection body, i. the hardened cement mortar, delivered to the surrounding soil.

If the protection of the excavation is no longer needed, then the strands 14 and the surrounding sheaths 18 can be completely removed again. For this purpose, it is only necessary to disengage the threaded engagement between the external thread 16a of the pressed on the strand 14 compression sleeve 16 and the internal thread 24a of the portion 24 of smaller diameter of the foot box 12. This thread engagement is particularly easy solve when the direction of impact R1 of the strand 14 (see FIG. 1 ) equal to the direction of rotation R2 of the thread 16a of the compression sleeve 16 (see FIG. 10 ). In this embodiment of the invention, the strands 14 pull together when unscrewing from the Fußbox 12 namely, so that the wires of the respective strand 14 do not open, but create more against each other and support each other. The strand 14 is characterized torsionally rigid over its entire length and can be unscrewed from the Fußbox 12 in a simple manner, what needs to be attacked only at their remote from the Fußbox 12 end.

Although in the illustrated embodiment both directions R1 and R2 are right-handed, i. the outer wires run in the sense of a rotation in a clockwise direction along the strands 14, a left-hand stroke of the strands connected to a left-hand thread in the Fußbox is conceivable.

It should be noted that although the strands 14 are each formed of seven wires 14a in the illustrated embodiment, the present invention is not limited to such strands. also, strands with a smaller number of wires, for example three wires, or a larger number of wires, for example nineteen wires, may be used.

It should also be noted that the Fußbox 12, the pressure hull 20 and the cladding tubes 16 remain after removal of the strands 14 in the ground. In order not to unnecessarily obstruct later construction measures on the property, in the soil of which these elements remain, the pressure bodies 20 are formed with predetermined breaking points 20c and 20d. For this purpose, their wall thickness radially inward at the bottom of the longitudinal recesses 20a (in FIG. 3 at 20c) and radially outward midway between two adjacent longitudinal recesses 20a (in FIG. 3 at 20d) each have a smaller value than the respective adjacent wall sections.

It should also be added that the foot box 12 may preferably be made of steel or cast material.

In the FIGS. 11 to 13 a second embodiment of a stranded pressure tube anchor according to the invention is shown, which is substantially the embodiment of the FIGS. 1 to 10 equivalent. Therefore, in the FIGS. 11 to 13 analog parts provided with the same reference numerals as in the FIGS. 1 to 10 , but increased by the number 100. Further, the stranded pressure tube anchor 110 is the FIGS. 11 to 13 in the following only described insofar as he from the stranded pressure tube anchor 10 of FIGS. 1 to 10 differs, whose description otherwise expressly referred to.

The stranded pressure tube anchor 110 differs from the stranded pressure tube anchor 10, first, in that it has not only three tension strands, such as the stranded pressure anchor 10, but four tension strands 114. However, each of these tension strands 114 can be constructed identically to the tension strands 14, in particular as regards the design of the compression sleeve 116 and its pressing on the strand 114.

Second, the stranded pressure tube anchor 110 differs from the stranded pressure tube anchor 10 in that not each of the strands 114 is associated with a separate cladding tube, but rather that all four strands 114 are accommodated in a common cladding tube 118. Accordingly, the foot box 112 also has only a single larger diameter portion 126. As in the embodiment of FIGS. 1 to 10 For example, the cladding tube 118 may be bolted to the foot box 112 or sealingly connected by press fitting.

Due to the design with a single cladding tube 118 and the requirement of minimizing the diameter of the required drill pipe, the pressure bodies 120 do not have longitudinal recesses corresponding to the longitudinal recesses 20a, into which supply lines for cement mortar are inserted could. In this variant, the cement mortar is filled over the Bohrverrohrung and pressed.

In the FIGS. 14 to 16 a third embodiment of a stranded pressure tube anchor according to the invention is shown, which is substantially the embodiment of the FIGS. 1 to 10 equivalent. Therefore, in the FIGS. 14 to 16 analog parts provided with the same reference numerals as in the FIGS. 1 to 10 , but increased by the number 200, ie compared to the FIGS. 11 to 13 increased by the number 100. Further, the strand pressure anchor 210 of the FIGS. 14 to 16 in the following only described insofar as he from the stranded pressure tube anchor 10 of FIGS. 1 to 10 differs, whose description otherwise expressly referred to.

The stranded pressure tube anchor 210 differs from the stranded pressure tube anchor 10, first, in that it has not only three tension strands, such as the stranded pressure anchor 10, but seven tension strands 214. However, each of these tension strands 214 can be constructed identically to the tension strands 14, in particular as regards the design of the compression sleeve 216 and its pressing on the strand.

Second, the stranded pressure tube anchor 210 differs from the stranded pressure tube anchor 10 in that the pressure bodies 220 could be inserted into the cement grout supply lines due to the requirement of minimizing the diameter of the required drill pipe, rather than the longitudinal grooves 20a. For pressing the cement mortar must therefore proceed as in the embodiment of the FIGS. 11 to 13 ,

Alternatively, however, a modification is conceivable in which only six strands are provided, and for the seventh strand, for example, the middle strand, provided space for laying a supply line for cement mortar is used. The receiving bore 222 'assigned to this supply line should be designed as a through hole, so that the Cement mortar the Fußbox 212 and the pressure body 220 sufficiently wrapped on the outside.

Claims (12)

1. Strand pressure-pipe anchor (10), comprising:

   - a pressure anchor base element (12),

   - a tension strand (14) or a plurality of tension strands (14),

   - at least one sheath (18), in which the tension strand (14) or at least one of the tension strands (14) is received,

   characterised in that the tension strand (14) or at least one of the tension strands (14) is provided, at the end thereof associated with the pressure anchor base element (12), with a ferrule (16) which is provided with an external thread (16a) which, in a connected state of the tension strand (14) and the pressure anchor base element (12) in which the tension strand (14) is connected to the pressure anchor base element (12) in order to transfer the anchoring forces to the surrounding subsoil, is in threaded engagement with an internal thread (24a) of the pressure anchor base element (12).
2. Strand anchor according to claim 1, characterised in that the direction of lay (R1) of the tension strand (14) or at least one of the tension strands (14) is the same as the direction of rotation (R2) of the thread (16a) of the ferrule (16) arranged at the free end thereof.
3. Strand anchor according to either claim 1 or claim 2, characterised in that the sheath (118) or at least one of the sheaths (18; 218) is connected to the pressure anchor base element (12; 112; 212) in a sealing manner.
4. Strand anchor according to claim 3, characterised in that the pressure anchor base element (12) comprises, on the surface thereof facing the tension strand (14) or the plurality of tension strands (14), a depression (26) for the sheath (118) or at least one of the sheaths (18; 218), into which depression the free end of an associated sheath (18; 118; 218) can be inserted.
5. Strand anchor according to either claim 3 or claim 4, characterised in that the sheath (118) or the at least one of the sheaths (18; 218) is screwed to the pressure anchor base element (12).
6. Strand anchor according to any of claims 1 to 5, characterised in that, if a plurality of tension strands (14) are provided, a separate sheath (18; 218) is associated with at least one tension strand (14), preferably with all of the tension strands (14).
7. Strand anchor according to any of claims 1 to 6, characterised in that it further comprises at least one pressure body (20), which cooperates with the pressure anchor base element (12) in transferring the anchoring forces to the surrounding subsoil.
8. Strand anchor according to claim 7, characterised in that the pressure body (20) encloses the tension strand (14) or the plurality of tension strands (14), and an end face of said pressure body which faces the pressure anchor base element (12) rests, preferably in a planar manner, against the pressure anchor base element (12) or a further pressure body (20).
9. Strand anchor according to either claim 7 or claim 8, characterised in that, on the outer peripheral face thereof, the pressure body (20) comprises at least one depression (20a) extending substantially in parallel with the longitudinal extension direction of the tension strand (14) or the plurality of tension strands (14).
10. Strand anchor according to any of claims 7 to 9, characterised in that a plurality of ribs (20b) extending in the peripheral direction are provided on the outside of the pressure body (20).
11. Strand anchor according to any of claims 7 to 10, characterised in that, in the peripheral direction at a point (20d) where a through-opening intended for the passage of the tension strand (14) or of one of the tension strands (14) extends furthest outwards radially, the pressure body (20) is designed to be free of ribs (20b) extending in the peripheral direction.
12. Strand anchor according to any of claims 1 to 11, characterised in that the sheath (18) is dimensioned and/or formed, at least at the end portion thereof adjacent to the pressure anchor base element (12), in such a way that, during insertion into the sheath (18) connected to the pressure anchor base element (12), the external thread (16a) of the ferrule of the associated tension strand (14) is inserted into the internal thread (24a) of the pressure anchor base element (12) only by the insertion movement of the tension strand (14).

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