EP2257690B1 - Corrosion-protected self-drilling anchor and anchor subunit and method for the production thereof - Google Patents

Abstract

A corrosion-protected, self-drilling anchor and an anchor subunit and to a method for the production thereof is provided. A self-drilling anchor of the invention includes a number of anchor subunits, each with a hollow bar element, which are connected together by the formation of an axial bell butt joint to form a connected pull and pressure member. The first subunit t its end has a drill bit and the subunit is connected non-rotatably with its end to a drilling and injection device. It is provided according to the invention that each hollow bar element is surrounded by a sheathing except for its end sections and the annular gap between the sheathing and hollow bar element is grouted with a first corrosion protection compound. A coupler in the area of the bell butt joint fits tightly against the sheathings of the two hollow bar elements which are part of the bell butt joint. The hollow space between the coupler and hollow bar elements is filled with a second corrosion protection compound. A method of the invention provides for the prefabrication of a number of anchor subunits at the factory to drill these into the substrate at the site of the anchor to be produced and thereby for connecting them together with the formation of bell butt joints, whereby in the area of the bell butt joint a coupler fits tightly against the ends of two neighboring sheathings and the hollow space between the coupler and hollow bar element is filled with a second corrosion protection compound.

Description

Technical area:

The invention relates to a corrosion-protected self-drilling anchor according to the preamble of patent claim 1, a method for its production according to independent claim 10 and a prefabricated anchor assembly according to independent claim 15.

State of the art:

Soil and rock anchors as well as piles are used in civil engineering whenever it comes to inducing forces in the area of the anchor or pile head into deeper soil layers. This applies equally to anchor and nails loaded by tension and to piles loaded with pressure or tension. For this purpose, anchor, nails or piles on a support member which is brought in a wellbore with the surrounding ground in non-positive association and anchored at the air side end in the region of the head. Since the support members are usually made of steel, they are sensitive to corrosion.

In this case, a distinction is made between support members for temporary use and support members for permanent use, the latter use requires a design suitable for protection against corrosion constructive training. A double or increased corrosion protection is then spoken of when a passivation of the steel surface of the support member is ensured by injecting a cement mortar and an additional, the armature enveloping plastic tube is a diffusion barrier for liquids.

A special case among the anchors is the self-drilling anchor, whose applications are mainly in the production of soil nails, micropiles and Temporärankem. Selbstbohranker like from the CH 693 934 , which is known as the closest prior art, consist essentially of a number of Anchor rods with a continuous axial cavity. At the end of the first anchor rod a drill bit is arranged with rinsing nozzles, which are connected via the continuous axial cavity with a drilling and Injiziereinrichtung at the air side anchor end. The extension of the self-drilling anchor after drilling a respective anchor rod is done by forming a Muffenstoßes. If a self-drilling anchor has reached its predetermined length, the resulting bore hole is injected with cement mortar through the axial cavity and, if appropriate, the anchorage is hardened after the injection material has hardened.

The advantages of such an anchor are initially in the rapid construction progress that is achieved by drilling and moving the anchor and injecting the well in one operation. So it is not a separate anchor installation and no piping and linkage removal necessary. However, the design of a self-drilling anchor as well as the production method determined by this do not allow the implementation of an increased corrosion protection, which is a prerequisite for a permanently protected support member.

Presentation of the invention:

Against this background, the object of the invention is to further develop known self-drilling anchors, in order to make them suitable for permanent use even in a corrosion-prone environment. A further object of the invention is to specify a method and prefabricated anchor subunits for producing such an anchor.

This object is achieved by a self-drilling anchor with the features of independent claim 1, by a method having the features of independent claim 10 and prefabricated Anchor units the features of independent claim 15.

Advantageous embodiments will be apparent from the dependent claims.

Until the invention, it was considered impossible in the art to equip self-drilling anchors with a double corrosion protection. On the one hand, there were fears that the factory pre-injected and already hardened anticorrosion compound, usually a cement or resin-bonded mortar or suspension, gets cracked during the drilling process between cladding tube and anchor rod and the corrosion protection is damaged, on the other hand, there was no satisfactory solution, the corrosion protection in the joint area of two hollow rods guarantee. The self-drilling anchor therefore failed to operate in a highly corrosion-prone environment.

It is the merit of the invention to have overcome this prejudice and to provide a self-drilling anchor, which also meets the requirements of increased corrosion protection. For this purpose, the invention provides a solution that ensures corrosion protection both in the area of the hollow rods and the joint area. This is achieved by an axially continuous combination of cladding and socket pipes, which represent a first barrier against externally coming, corrosion-causing substances. The cavity formed thereby to the hollow bar element is filled in each case with a corrosion protection compound, which forms the second barrier against corrosion, which is why it is spoken of a double corrosion protection. An anchor according to the invention therefore combines for the first time the advantages of a self-drilling anchor with the advantages of a double corrosion-protected anchor or pile.

In the region of the cladding tube, the cavity is filled up with a first anticorrosion compound which consists of a hardenable material, for example a mortar or a suspension based on cement or synthetic resin. In the region of the sleeve tube, ie in the joint area, the cavity filling consists of a second anticorrosion compound, which differs in its kind from the first anticorrosion compound and consists for example of a plastically deformable material such as grease and the like.

According to a particular embodiment of the invention, in each case an adapter is provided at the ends of the cladding tube, which already close the frontal openings of the cladding tubes close to the hollow bar during manufacture of the prefabricated anchor subunits and at the same time enables a tight connection of the sleeve tube. For this purpose, the adapter preferably has a cylindrical seat, on which the sleeve tube is axially plugged, wherein in the insertion region means for Position assurance and sealing of the sleeve tube may be arranged, for example in the form of a circumferential bead. In order not to increase the outer diameter of the self-drilling anchor, it is advantageous to provide a radial recess in the region of the cylindrical seat for receiving the sleeve tube.

The cladding tube and the adapter thus form a cavity surrounding the hollow, tightly closed cavity, which makes it possible to prefabricate by default pre-injecting this cavity with a hardenable anticorrosive Anchoring units as standard. In the context of the invention, however, is also a production of the anchoring units, in which instead of the adapters, which act as a lost formwork, the end faces of the cavity are closed only temporarily for the Injiziervorgang and until the hardening of the suspension.

The factory production of these Anchor Units offers the great advantage that can be produced under consistently optimal conditions and independent of climatic influences. This ensures a consistently high quality of the anchoring units produced in this way with a corresponding increase in quality in the finished self-drilling anchor. In addition, the anticorrosion composition within the cladding tube without regard to the subsequent pressing of the borehole can be specially adapted to the requirements of optimum corrosion protection, for example, by its particular composition and the manner of its introduction. For the pressing of the borehole after the anchor has been installed, then a likewise optimized for this application cement mortar can be used.

A further preferred embodiment of the invention also has a drill bit with a nozzle with obliquely forwardly pointing outlet openings in the drilling direction. The pressure jet emerging from the nozzle loosens the substrate lying in front of the nozzle and can even loosen and crush it when high pressures are applied. For the same purpose, alternatively or cumulatively, the arrangement of a nozzle with a radial outlet opening can be provided. This results in the advantage that the loosened substrate for the drill bit can be solved more easily, so that as far as possible vibration-free propulsion is possible. This minimizes the risk of crack formation in the area of the pre-injected corrosion protection of the hollow bar anchor.

Brief description of the drawings:

Fig. 1

eine Seitenansicht auf einen erfindungsgemäßen Selbstbohranker, zum Teil aufgebrochen,

Fig. 2

eine Teilansicht des in Fig. 1 dargestellten Selbstbohrankers im Bereich des Muffenstoßes in größerem Maßstab, zum Teil aufgebrochen,

Fig. 3

einen Querschnitt durch die in Fig. 1 dargestellte Teileinheit B entlang der dortigen Linie III - III,

Fig. 4

einen Querschnitt durch die in Fig. 1 dargestellte Teileinheit B entlang der dortigen Linie IV - IV,

Fig. 5

einen Längsschnitt durch den in Fig. 1 dargestellten Selbstbohranker im Bereich der Bohrkrone,

Fig. 6

eine Seitenansicht auf einen erfindungsgemäßen Selbstbohranker als Pfahl, zum Teil aufgebrochen, und die

Figuren 7 a-f

die verschiedenen Verfahrensschritte zur Herstellung eines erfindungsgemäßen Ankers.

The invention will be explained below with reference to an embodiment shown in the drawings. Show it

Fig. 1

a side view of a self-drilling anchor according to the invention, partly broken,

Fig. 2

a partial view of the in Fig. 1 illustrated Selbstbohrankers in the field of Muffenstoßes on a larger scale, partially broken,

Fig. 3

a cross section through the in Fig. 1 shown subunit B along the line there III - III,

Fig. 4

a cross section through the in Fig. 1 shown subunit B along the line there IV - IV,

Fig. 5

a longitudinal section through the in Fig. 1 illustrated self-drilling anchor in the field of drill bit,

Fig. 6

a side view of a self-drilling anchor according to the invention as a pile, partially broken, and the

Figures 7 af

the various process steps for producing an anchor according to the invention.

Ways to carry out the invention and commercial usability:

In Fig. 1 an inventive self-drilling anchor 1 is shown in an overview, as it can be used advantageously in injectable soils. In the present example, the armature 1 consists of two factory-prefabricated subunits A and B of essentially the same design, which are pushed together in a force-locking manner along the armature longitudinal axis 2. The length of units A and B can be as required vary between 1 m and 6 m. By juxtaposing a predetermined number of subunits A, B, each with a predetermined length, an inventive anchor 1 in the desired overall length can be produced.

The structural design of the subunits A, B also goes from the FIGS. 2, 3 and 4 out. One sees a hollow rod member 3, which is provided over its entire length with an external thread 4 and which has an axial through hole 5 in the region of its longitudinal axis 2. The hollow bar element 3 is surrounded over its entire length, except for its end sections 3 ', 3 ", by a ribbed jacket tube 6. The two ends of the ribbed jacket tube 6 are connected tightly to the hollow bar 3 by means of the adapters 7. For this purpose the adapter 7 has a connection piece 8, onto which the jacket tube 6 is pushed axially, and in the direction of the one end section 3 'a cylindrical seat 9, the jacket surface of which has a peripheral bead Hollow bar element 3 is factory completely filled with a first corrosion protection compound 10, for example with a curable injection mortar.

In this way, the diffusion-tight material properties of the cladding tube 6, together with the properties of the injection mortar 10 that achieve the passivation of the steel surface, result in double corrosion protection.

By frictional axial joining together a plurality of such prefabricated subunits A, B anchor 1 can be made of any length. For joining together a socket joint is provided, the constructive training to achieve a corrosion protection mainly from Fig. 2 evident. There you can see the free end portions 3 'of two axially opposite hollow rod elements 3, which are connected by means of a screw sleeve 8 tensile and pressure-resistant together.

The joint area is also surrounded over the entire length of the end portions 3 'by a sleeve tube 12, which bears tightly against the cylindrical seat 9 of the adapter 7 with its ends while maintaining a slight axial play. The cavity between the sleeve tube 12 and the end portions 3 'of the hollow rods 3 and der Screw sleeve 11 is filled with a second anticorrosion compound 13, for example with a grease.

Thus, a double corrosion protection is also present in the joint area, which is formed on the one hand by the diffusion-proof sleeve pipe 12 and on the other hand by the corrosion protection compound 13. Over the length of an armature according to the invention thus results in an alternating sequence of longitudinal sections, in which once the pre-injected with the first anticorrosion compound 10 sheath 6 provides corrosion protection and once the filled with the second anticorrosion compound 13 sleeve tube 12th

The subunit A forms the beginning of an armature 1 according to the invention, the end portion 3 "of which is assigned to the bottom of the borehole not being intended to form a socket joint but to receive a drill bit 14. For this reason, the modified adapter 7 'arranged at the end 3" does not have a cylindrical one Seat 9 on.

The structural design of the drill bit 14 goes out Fig. 5 according to which it has a cylindrical body 15, to which a cone tip 16 connects to one side. From the lateral surface of the apex 16 extend blades 17 in the radial direction with cutting 18 for releasing and conveying the substrate. From the other side of the cylindrical body 15, starting in the transition region between the cylindrical body 15 and the apex 16 extends in the longitudinal axis 2, a blind bore 19 with internal thread into which the hollow rod 3 of the subunit A with its end 3 "is screwed.

The drill bit 14 has a first injection nozzle 20, which extends from a bore perpendicular to the conical surface up to the blind bore 19, and a second nozzle 21, which is formed by a bore perpendicular to the cylindrical surface of the body 15, ie radially. In this way, together with the cavity 5 of the individual hollow rod elements 3, a continuous cavity over the entire length of the armature 1 up to the nozzles 20 and 21 results.

The subunit B forms the air-side end of the armature 1, so that here also the free end 3 "of the hollow rod 3 is not used to form a Muffenstoßes, but to form the air-side anchoring.

To the end portion 3 "is an anchor plate 22 is inserted, which is intended to support against the ground 25. A sealing tube 23 is fixedly connected to the underside of the anchor plate 22 and surrounds the Ripprohr 6 at a radial distance on the end portion 3" is finally screwed a cap nut 24, which is supported with its spherical peripheral surface on the anchor plate 22 and thus enables a tensioning of the armature 1. To complete the double corrosion protection, the cavity between sealing tube 23 and end section 3 "of hollow bar member 3 is also injected with a cement mortar.

In the case of anchors with more than two subunits, further subunits are interposed between the subunits A and B, the structure of which essentially corresponds to subunits A and B, with the difference that the further subunits have ends on both sides that correspond to the ends 3 'of the subunits A. and B correspond and thus allow both sides to form a Muffenstoßes.

The method for producing an armature 1 according to the invention will be described below with reference to FIGS FIGS. 7a to 7f explained in more detail.

Fig. 7a shows the beginning of the production of an armature according to the invention 1. For this purpose, a subunit A comprising a hollow rod member 3 with a drill bit 14 and a corrosion protection arranged behind it, consisting essentially of the Ripprohr 6 and the already factory introduced, hardened corrosion protection compound 10, with a not Further drilling equipment drilled in the underground drilled. At the same time, scavenging air or rinsing liquid is transported through the through-hole 5 to the nozzles 20 and 21 at the tip of the armature 1 under high pressure to loosen and loosen the ground. The dissolved material is then flushed out between the cladding tube 6 and the borehole wall.

Fig. 7b shows a state in which the borehole has reached a depth at which the subunit A projects substantially only with its end 3 'from the borehole. is reached this state, a screw sleeve 11 is screwed with its half length on the end 3 ', so that the other half of the screw sleeve 11 is for receiving the hollow bar 3 another subunit B available.

In order to ensure the corrosion protection in the joint area, however, a corrosion protection compound 13, for example in the form of grease, is applied generously to the sleeve 11 as well as to the exposed areas of the end 3 'of the hollow bar element 3 Fig. 7c is shown.

Subsequently, as in Fig. 7d shown, the sleeve tube 12 is pushed over the screw sleeve 11 until it sits with its end on the cylindrical seat 9 of the adapter 7.

Now, a new subunit, for example, the subunit B described above, are screwed into the thus prepared end of the subunit A. The further subunit also has an already factory-made corrosion protection in the region of the cladding tube 6, as described above. In order to complete the corrosion protection in the region of the socket joint, a corrosion protection compound 13 is also previously applied to the free end 3 'of the hollow rod member 3 of the subunit B and then screwed into the threaded sleeve 11. In this case, the sleeve tube 12 pushes with its free edge on the cylindrical seat 9 of the adapter 7 and thus forms a continuous and sealed connection of the ribbed sheaths 6 of the two subunits A and B.

After completion of the armature 1 with the unit B, the hole, as already under Figure 7a described, continue to be driven. This condition is in Fig. 7e shown.

After reaching the predetermined hole depth, the anchorage is applied at the end of the anchor 1. For this purpose, an anchor plate 22 with attached sealing tube 23 is pushed onto the end 3 "of the hollow rod member 3 of the subunit B until the anchor plate 22 rests flat against the substrate 25. Subsequently, a cap nut 24 is screwed onto the end 3" until it is crowned Bottom of the anchor plate 22 abuts. The completion of the armature 1 is done by pressing the borehole, that is, the annular gap between sheath 6 and borehole wall with a Cement mortar and optionally by tensioning the anchor 1 after the cement mortar has hardened.

FIG. 6 shows the use of a self-drilling anchor 26 according to the invention as a post 30. Up to the air side anchoring of the pile 30, the pile 30 has an identical structure to that of the FIGS. 1 to 5 described anchor 1, so that the same reference numerals are used for the same features and reference is made to avoid repetition to the local part of the description.

Since the pile 30 is intended to integrate with its air-side end in a - not shown - concrete pile cap plate, an anchor plate 27 is fixed between a nut 28 and a lock nut 29 in a predetermined position. Since this area is completely enclosed at a later time by the concrete of the pile top plate, can be dispensed with a sealing tube.

Claims (15)

1. A corrosion-protected, self-boring anchor (1,30) to be arranged within a borehole, comprising a plurality of anchor subunits (A,B), each having a hollow rod element (3) which can be joined together by forming an axial socket joint to form a coherent tension and pressure member, wherein the first subunit (A) has a boring head (14) and the last subunit (B) can be connected in a manner precluding relative rotation to a drilling and injection device, characterised in that each hollow rod element (3) is surrounded by a sheathing tube (6) except for its end sections (3,3'), and the annular gap between the sheathing tube (6) and the hollow rod element (3) is pressure-grouted with a first corrosion protection compound, and in that a socket tube (12) provided in the vicinity of the socket joint abuts fluidtightly against the sheathing tubes (6) of the two hollow rod elements (3) which are part of the socket joint, wherein the hollow space between the socket tube (12) and the hollow rod elements (3) is filled with a second corrosion protection compound (13).
2. A self-boring anchor according to Claim 1, characterised in that at each end of the sheathing tube (6) of a subunit (A,B) there is provided a respective adapter (7,7') seated on the hollow rod element (3) and to which the socket tube (12) can be connected at its ends.
3. A self-boring anchor according to Claim 2, characterised in that the adapter (7,7') respectively seals fluidtightly the hollow space between the sheathing tube (6) and the hollow rod element (3) at their end faces.
4. A self-boring anchor according to Claim 2 or 3, characterised in that the adapter (7) has a cylindrical seat (9) for the socket tube (12).
5. A self-boring anchor according to Claim 2 or 4, characterised in that at least one annular bead is arranged in the contact surface between the adapter (7) and the socket tube (12).
6. A self-boring anchor according to any one of Claims 2 to 5, characterised in that the adapter (7) in the overlap region with the socket tube (12) has a radial recess towards the anchor longitudinal axis (2), which preferably corresponds to the thickness of the socket tube (12).
7. A self-boring anchor according to any one of Claims 1 to 6, characterised in that the boring head (14) has a nozzle (20) whose outlet opening produces an outlet jet which is directed obliquely forwards.
8. A self-boring anchor according to any one of Claims 1 to 7, characterised in that the boring head has a nozzle (21) whose outlet opening produces a radial outlet jet.
9. A self-boring anchor according to any one of Claims 1 to 8, characterised in that the hollow space between the sheathing tube (6) and the borehole wall is pressure-grouted with cement grout which differs in its type from the first corrosion protection compound (10).
10. A method for producing a corrosion-protected, self-boring anchor (1,30), characterised by the following method steps:

    a) preparing a plurality of anchor subunits (A,B) by applying a sheathing tube (6) to a hollow rod element (3) and injecting the hollow space between the sheathing tube (6) and the hollow rod element (3) with a first curable corrosion protection compound,

    b) attaching a boring head (14) to one end (3") of the first hollow rod element (3) and drilling the first subunit (A) into the ground with simultaneous flushing through the hollow rod element (3) with a fluid until the first subunit (A) is situated in the borehole over the majority of its length,

    c) creating a socket joint between the hollow rod element (3) of a first anchor subunit (A) and the hollow rod element (3) of another prepared second anchor subunit (B),

    d) connecting the sheathing tubes (6) of the two anchor subunits (A,B) by applying a socket tube (12) in the vicinity of the socket joint,

    e) continuing the boring process by flushing with a fluid until the second subunit (B) is situated in the borehole over the majority of its length,

    f) repeating the method steps c),d) and e) until the self-boring anchor (1,3) has reached its intended length,

    g) producing the air-side anchoring,

    h) injecting the hollow space between the sheathing tube (6) and borehole wall with cement grout.
11. A method according to Claim 10, characterised in that step d) is carried out firstly by connecting a socket tube (12) to the air-side end of the sheathing tube (6) of the first subunit (A) before creating the socket joint and then by connecting the sheathing tube (6) of the further subunit (B) to the socket tube (12) after creating the socket joint.
12. A method according to Claim 10 or 11, characterised in that the hollow space between the sheathing tube (6) and the hollow rod element (3) in the vicinity of the socket joint is filled with a corrosion protection compound (10).
13. A method according to any one of Claims 10 to 12, characterised in that the during the boring the ground is broken up in the area in front of and/or to the side of the boring head (14).
14. A method according to Claim 13, characterised in that the breaking up of the ground is effected by jet grouting.
15. A prefabricated anchor subunit (A,B) for producing a corrosion-protected, self-boring anchor (1), with a hollow rod element (3), characterised in that it is surrounded at both of its ends by a coaxially arranged sheathing tube (6), wherein the annular space between the sheathing tube (6) and the hollow rod element (3) is filled with a cured corrosion protection compound (10).

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