EP2550404B1 - Device for an at least partially removable anchor and method for at least partially removing an anchor - Google Patents
Device for an at least partially removable anchor and method for at least partially removing an anchor Download PDFInfo
- Publication number
- EP2550404B1 EP2550404B1 EP10711318.5A EP10711318A EP2550404B1 EP 2550404 B1 EP2550404 B1 EP 2550404B1 EP 10711318 A EP10711318 A EP 10711318A EP 2550404 B1 EP2550404 B1 EP 2550404B1
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- EP
- European Patent Office
- Prior art keywords
- induction coil
- tension member
- anchor
- carrier tube
- tension members
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Images
Classifications
-
- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D5/00—Bulkheads, piles, or other structural elements specially adapted to foundation engineering
- E02D5/74—Means for anchoring structural elements or bulkheads
- E02D5/76—Anchorings for bulkheads or sections thereof in as much as specially adapted therefor
- E02D5/765—Anchorings for bulkheads or sections thereof in as much as specially adapted therefor removable
Definitions
- the present invention relates to a device for an at least partially removable anchor and a method for at least partially removing an anchor.
- Temporary prestressed anchors are often used to anchor the vertical walls of excavations.
- Such prestressed anchors are composed for example of a bundle of parallel extending Siebendrähtiger prestressing steel strands, which serve as tension members.
- the strands are fixed by means of clamping wedges in an anchor head.
- the strands run individually or in a collective PE tube, without any bond with the foundation ground and freely stretchable via the so-called “free anchor length” L fr up to an anchoring body.
- anchoring length L v the bare strands are connected in the anchoring body by means of injected cement mortar with the ground, in order to transmit the forces applied to the anchor head forces in the ground.
- anchors without anchoring length L v so-called pressure tube anchors are used, in which the free anchor length L fr extends to the anchor end, from where the anchor force is introduced via a pressure member enclosing the draft tube in the ground.
- conventional anchors have a breaking load of 400 to 2500 kN and a setting force of 240 to 1500 kN, which are offset in lateral and vertical distances of 2 to 4 m.
- the anchors are composed according to the depth of the pit and the forces acting on the anchored structure forces typically from a free anchor length L fr of 7 to 25 m and - if available - an anchoring length L v of 4 to 8 m together and depending on the depth of the Excavation in several, staggered in depth layers installed.
- L fr free anchor length
- L v anchoring length
- the majority of anchors come to lie beneath neighboring properties.
- the anchors lose their function. If the whereabouts of the tension members in the ground e.g. is undesirable because of later proposed in this area, the anchors must be as far as possible, i. at least their over the free anchor length extending part are removed.
- the method is known to produce predetermined breaking points at the transition L fr - L v by mechanical or thermal weaknesses of the tension members and to remove the free anchor length, the tension members at the predetermined breaking point by applying appropriate forces on the anchor head demolish (see, eg DE 195 00 091 C1 ).
- This method has serious disadvantages.
- the lost through the weakening of the tension members cross section must be compensated by additional, also weakened tension members.
- the weakened tension members have a relatively rigid behavior, so that the break occurs abruptly and does not announce itself by a previous stretching. An abrupt failure of an anchor is undesirable in particular with regard to system security.
- a disadvantage is, inter alia, that a uniform heating of the tension member is difficult and not always a complete separation takes place. For example, if several strands are present, they are not heated due to their different location in the hole exactly at the same time and thus not at the same time to break against. The first broken wires can lead to premature release of the anchoring on the anchor head, whereby the voltage on the not yet broken wires is eliminated and they do not break.
- the cable runs to the power supply of the induction coil between serving as tension members strands and can also be easily damaged.
- the cavities between the strands and the collecting duct are not sealed air-side in the region of the separation point, so that in the free anchor length L fr penetrating water can accumulate in the region of the separation point.
- the heating of the strands due to continuous cooling by the heating and evaporation of the Water practically impossible or at least delayed until the water has evaporated completely.
- the strands thus function in a similar way to the heating rods of an immersion heater to heat water.
- Object of the present invention is to improve the known devices and methods so that the tension member of an anchor is separable in a simpler and more reliable manner.
- the invention is based on the finding that contrary to the teaching of the EP 0 583 725 A1 no additional electrically conductive metal tube is required in order to heat a tension member beyond the Curie temperature to the melting point can. If the tension member is sufficiently biased during the heating process, a reliable separation at temperatures below the melting point is possible.
- Fig. 1 shows an excavation 1, the vertical Baugrubenab gleich is secured with an anchored structure 19.
- the anchoring is ensured by prestressed armature 5, which are connected via an anchor head 6 to the structure 19.
- Each anchor 5 is installed in a previously drilled in the ground 3 hole 4 and extends below a neighboring plot. 2
- each armature 5 are each designed, for example, as a seven-stranded prestressing steel strand and have a free anchor length (L fr ) 7 guided by a collecting duct 10 and an anchoring length (L v ) 8 joined to the ground 3 by cement mortar 11 in a force-transmitting manner.
- a separator 13 for separating the tension members 9 in the armature 5 is integrated.
- a cable 18 for powering the separator 13 extends outside of the collecting tube 10 and is attached thereto.
- the injection line, through which the cement mortar is passed for anchoring, also runs outside the collecting duct 10 (not shown). When attaching the anchor injection line and cable 18 are secured together on the collecting tube 10 and inserted into the borehole 4.
- Fig. 2 shows the structure of a first embodiment of the separation device 13 for separating the tension members 9 at the separation point 12.
- the separation device 13 with an induction coil in the form of a single-layer winding 16 (inductor) of thermally insulated copper wire, wound on a support tube 15, equipped.
- the winding 16 has a number of turns which is in the range of 5 to 50, preferably 10 to 30.
- the cable 18 for powering the winding 16 is connected to the two ends of the winding 16 and extends outside of the support tube 15. Thus, the cable 18 is protected against damage during pretensioning of the tension members 9.
- the support tube 15 is rigid to prevent displacement of the induction coil 16 relative to the tension members 9 and any resulting damage thereto, and is made of a material that is electrically insulating and non-ferromagnetic. Due to the rigidity of the support tube 15, inter alia, it is prevented that the forces occurring after the installation of the armature deform the support tube 15 at least over the region of the induction coil 16.
- a material for the support tube 15 is eg glass fiber material, PE, PP or PVC.
- the separating device 13 is arranged substantially centrally in the borehole 4 and the cavity between the rear end of the separating device 13 and the ground 3 is filled with cement mortar 11.
- the induction coil 16 is supplied in operation via the electric cable 18 with higher frequency power to heat the tension members 9 inductively to breakage.
- the cavities between the support tube 15 and the tension members 9 are filled with a filling 17.
- a filling 17 Cement-water mixture with the possible addition of one or more additives, e.g. Propellant, plasticizer and setting accelerator, plastic-based mortar with thermally insulating additives, putty, etc.
- additives e.g. Propellant, plasticizer and setting accelerator, plastic-based mortar with thermally insulating additives, putty, etc.
- Fig. 2 further shows, the air-side end of the support tube 15 is inserted into the collecting duct 10.
- Spacers 20 are inserted at the end of the support tube 15 and have passages through which the tension members 9 extend.
- the spacers 20 are made of a solid or relatively solid material, such as metal or plastic. They ensure, in particular during assembly of the separating device 13, that the part of the tension members 9, which runs inside the carrier tube 15, comes to lie in a predetermined position with respect to the induction coil 16.
- this position is chosen symmetrically, so that the tension members 9 as uniform as possible generated by the induction coil 16 magnetic field are penetrated and thus the most uniform and simultaneous heating is achieved.
- the number of passages in the spacer 20 is arbitrarily adaptable to the number N of the tension members provided at the anchor.
- the spacer 20 may be designed for anchors with 8 - 12 strands or 13 - 19 strands as tension members.
- Fig. 4 shows the cross section through the separator 13 at the separation point 12.
- the separator 13 is arranged substantially centrally in the borehole 4 in the ground 3 and outside filled with cement mortar 11.
- seven tension members are provided, which are each formed as a strand 14 with seven wires and enclosed by the wound on the support tube 15 induction coil 16.
- This has an outer diameter D a and an inner diameter Di, wherein the ratio D a to D i is at most 1.5 and preferably at most 1.25. This ensures that the lateral extent of the separating device 13 corresponds approximately to the diameter of the collecting duct 10 and that no enlargement of the borehole 4 is required.
- Fig. 6 shows a longitudinal section through a structure of a separating device 13 according to a second embodiment for separating the tension members 9 at the separation point 12.
- the separation device 13 with an induction coil in the form of a single-layer winding 16 (inductor) of a single or two-wire electric cable 18, wound directly on the collecting duct 10, equipped.
- the electric cable 18, which leads along the collecting duct 10 to the outside, thus serves directly to form the winding 16. A transition between the electric cable and winding is thus eliminated.
- the winding 16 has a number of turns, which is in the range of 5 to 50, preferably 10 to 30.
- the winding is fixed on the collecting tube 10 by a shrink tube 23.
- the electric cable 18 extends outside the collecting duct 10 to the anchor head 6 and is thereby protected against damage during pretensioning of the tension members 9.
- the cavities between the collecting duct 10 and the tension members 9 are filled with a filling 17.
- the filling 17 is bounded on both sides by spacer pins 21, which are made of an elastically deformable material, such as rubber.
- the collecting duct 10 is locally compressed by means of steel strips 22, which are tensioned with a sufficiently large force, so that the play between the tension members 9 and the collecting duct 10 closes with respect to the spacer pin 21.
- Fig. 7 shows the cross section through the separator 13 at the separation point 12th
- Fig. 8 shows the distance pin 21 for a tension member consisting of 4 prestressing steel strands 14 with the passages 21.1 to 21.4.
- the spacer pin 21 has a length which is at least equal to the width of the steel strip 22nd
- Fig. 9 shows a longitudinal section through a structure of a separating device according to a third embodiment, which is mounted after the bitumen filling 24 at the end of the collecting duct of the free anchor length L fr .
- the end of the collecting sleeve 10 is poured out against the cement mortar 11 injected into the anchoring length 8 with a hot-filled bitumen filling 24, which is fixed with steel bands 22 opposite the collecting sleeve 10.
- the winding 16 consisting of turns of the electric cable 18 is seated on a support tube 15, which with a shrink tube 23 against the collecting tube 10 and the anchoring length 8 forming part of the tension members 14th is fixed.
- the cavities between the support tube 15 and the tension members 9 are filled directly by the cement mortar 11 injected into the anchoring length 8.
- the support tube 15 is sealed at the air-side end, but open at the mountain end, so that the injection material 11 can penetrate during injection into the support tube 15 and this can fill.
- Fig. 10 shows the cross section through the separator 13 at the separation point 12th
- the support tube 15 is sealed on the biasing part of the tension members 9 side facing the separation point 12, on the one hand, a passage of water and on the other a passage of injection material 11 are prevented. This ensures that, on the one hand, the injection material 11 does not reach the prestressable part of the tension members 9 during injection and, on the other hand, no water can penetrate from the outside to the separation point 12, thus enabling efficient heating of the tension members 9.
- the respective strand 14 of the tension member 9 has a core around which wires are wound whose diameter is smaller than the diameter of the soul. This ensures that during the heating process, the soul, which is additionally heated by the surrounding wires, not the first rips, but all the wires of the strand 14 are separated simultaneously.
- the tension members 9 of the prestressed ground and rock anchors 5 are usually biased to about 60% of the breaking force. Since an anchor 5 can be embedded in the ground for a long time, it must be ensured for the removal by means of the separating device 13 that the tension members 9 are still sufficiently prestressed.
- the bias voltage is selected so that during the heating process by the induction coil 16, the respective tension member 9 is biased with a force corresponding to at least 10%, preferably at least 25% and more preferably at least 50% of the breaking force of the tension member 9 at 0 degrees Celsius.
- the tension members 9 Due to sufficient preload it is possible to separate the tension members 9 at relatively moderate temperatures, which are below the melting point and typically below 700 degrees Celsius and even below 600 degrees Celsius. If the strength of the tension member 9 is lowered by heating below the voltage applied in the tension member 9, this tears. Due to the tension of the torn-off part of the tension member 9 will jump out of the anchor head. For safety reasons, therefore, the anchor head is covered during the heating process with a hood to catch the tension members 9 after the break.
- Fig. 5 shows the curve of the strength F as a function of the temperature T for a drawn prestressing steel wire, where F is normalized to the value of the strength at 0 degrees Celsius. As can be seen, the strength at temperatures above 600 ° C falls below 10% of the original value. Accordingly, the higher the bias voltage during the heating operation, the lower the temperatures are sufficient to cause the tension member 9 to crack.
- the separator 13 need not be designed to allow heating above the Curie temperature (for Fe 768 ° C) to the melting point as in the apparatus of FIG EP 0 583 725 A1 the case is.
- no electrically conductive metal tube is required, which is arranged in the region between the induction coil 16 and the separation point 12 and the tension members 9 heated by heat conduction and heat radiation. The magnetic field generated by the induction coil 16 can therefore freely penetrate into the tension members 9 and heat them.
- the load oscillating circuit is constructed as a parallel resonant circuit, which has power condensers as elements and the winding 16 connected via the cable 18. Capacitance and inductance of these elements determine the working frequency.
- the load circuit is connected to a power source, which includes a connectable to the usual power grid main transformer, a rectifier, a chopper and a smoothing part.
- the load circuit is connected to an H-bridge, which is controlled by the chopper.
- the design of the power supply in the form of a circuit with electronic components allows a compact and relatively lightweight construction.
- the static frequency converter is much lighter than a dynamic frequency converter can be built and typically weighs less than 100 kg, and preferably less than 50 kg.
- the magnetic field optimized which is used to heat the tension members 9.
- the induction coil 16 can be acted upon by a current which is above 2.5 A, preferably above 5 A and particularly preferably above 10 A, and which has a frequency f of more than 1 kHz and preferably more than 10 kHz.
- the frequency is in the range of 30-50 kHz.
- the power delivered by the frequency converter is greater than 1 kW and preferably greater than 3 kW, e.g. at 5 kW.
- the heating power which is induced by means of the induction coil 16 in the tension members 9, increases with increasing frequency f of the flow.
- the penetration depth of the current decreases as the frequency f increases.
- the cable 18 is at least 5 m and preferably at least 10 m long and is a commercially available cable, for example one with more than two wires and / or with wires each having a cross section of at least 1.5 mm 2 .
- the respective core can be designed either as a single wire or as a stranded wire. If a cable 18 is used with four wires, so the two opposite wires are advantageously connected together.
- the separation device 13 shown here is for removal (deconstruction) at least the free anchor length of the tension members of prestressed floor and rock anchors, as described, for example, in the Swiss standard "SIA 267 geotechnics" and "EN 1537 ground anchors".
- the separator is in addition to anchor with an anchoring length u.a. also suitable for those without anchoring length, in particular pressure tube anchor.
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- Engineering & Computer Science (AREA)
- Structural Engineering (AREA)
- Life Sciences & Earth Sciences (AREA)
- General Life Sciences & Earth Sciences (AREA)
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- General Engineering & Computer Science (AREA)
- Piles And Underground Anchors (AREA)
Description
Die vorliegende Erfindung bezieht sich auf eine Vorrichtung für einen zumindest teilweise ausbaubaren Anker und ein Verfahren zum zumindest teilweisen Ausbau eines Ankers.The present invention relates to a device for an at least partially removable anchor and a method for at least partially removing an anchor.
Zur Verankerung der vertikalen Wände von Baugruben werden häufig temporäre vorgespannte Anker eingesetzt.Temporary prestressed anchors are often used to anchor the vertical walls of excavations.
Solche vorgespannte Anker sind beispielsweise aus einem Bündel parallel verlaufender siebendrähtiger Spannstahllitzen zusammengesetzt, die als Zugglieder dienen. Luftseitig sind die Litzen mittels Klemmkeilen in einem Ankerkopf festgesetzt. Dahinter verlaufen die Litzen - einzeln oder in einem Sammelhüllrohrs aus PE verrohrt - ohne Verbund mit dem Baugrund und frei dehnbar über die sogenannte "freie Ankerlänge" Lfr bis zu einem Verankerungskörper. In der anschliessenden sogenannten "Verankerungslänge" Lv sind die blanken Litzen im Verankerungskörper mittels injiziertem Zementmörtel mit dem Baugrund verbunden, um die am Ankerkopf aufgebrachten Kräfte in den Baugrund übertragen zu können.Such prestressed anchors are composed for example of a bundle of parallel extending Siebendrähtiger prestressing steel strands, which serve as tension members. On the air side, the strands are fixed by means of clamping wedges in an anchor head. Behind this, the strands run individually or in a collective PE tube, without any bond with the foundation ground and freely stretchable via the so-called "free anchor length" L fr up to an anchoring body. In the subsequent so-called "anchoring length" L v the bare strands are connected in the anchoring body by means of injected cement mortar with the ground, in order to transmit the forces applied to the anchor head forces in the ground.
Es werden auch Anker ohne Verankerungslänge Lv, sogenannte Druckrohranker verwendet, bei welchen sich die freie Ankerlänge Lfr bis an das Ankerende erstreckt, von wo aus die Ankerkraft über ein das Zugglied umschliessendes Druckrohr in den Boden eingeleitet wird.Also anchors without anchoring length L v , so-called pressure tube anchors are used, in which the free anchor length L fr extends to the anchor end, from where the anchor force is introduced via a pressure member enclosing the draft tube in the ground.
Je nach Baugrundqualität weisen gebräuchliche Anker eine Bruchlast von 400 bis 2500 kN und eine Festsetzkraft bzw. Gebrauchskraft von 240 bis 1500 kN auf, die in seitlichen und vertikalen Abständen von 2 bis 4 m versetzt angebracht werden.Depending on the quality of the ground, conventional anchors have a breaking load of 400 to 2500 kN and a setting force of 240 to 1500 kN, which are offset in lateral and vertical distances of 2 to 4 m.
Die Anker setzen sich entsprechend der Tiefe der Baugrube und den auf das verankerte Tragwerk einwirkenden Kräften typischerweise aus einer freien Ankerlänge Lfr von 7 bis 25 m und - falls vorhanden - einer Verankerungslänge Lv von 4 bis 8 m zusammen und werden je nach Tiefe der Baugrube in mehreren, in die Tiefe gestaffelten Lagen eingebaut. Dabei kann insbesondere in städtischen Gebieten der grösste Teil der Anker unter Nachbargrundstücke zu liegen kommen.The anchors are composed according to the depth of the pit and the forces acting on the anchored structure forces typically from a free anchor length L fr of 7 to 25 m and - if available - an anchoring length L v of 4 to 8 m together and depending on the depth of the Excavation in several, staggered in depth layers installed. Here, especially in urban areas, the majority of anchors come to lie beneath neighboring properties.
Sobald die vom verankerten Tragwerk aufgenommenen Kräfte im Laufe des Baufortschrittes auf das in der Baugrube errichtete Bauwerk abgegeben werden können, verlieren die Anker ihre Funktion. Falls der Verbleib der Zugglieder im Baugrund z.B. wegen später in diesem Bereich vorgesehener Bauten unerwünscht ist, müssen die Anker so weit möglich, d.h. mindestens ihren über die freie Ankerlänge verlaufenden Teil entfernt werden.As soon as the forces absorbed by the anchored supporting structure can be released in the course of the construction progress on the building erected in the excavation pit, the anchors lose their function. If the whereabouts of the tension members in the ground e.g. is undesirable because of later proposed in this area, the anchors must be as far as possible, i. at least their over the free anchor length extending part are removed.
Zum Ausbauen der Anker ist das Verfahren bekannt, vorgängig Sollbruchstellen am Übergang Lfr - Lv durch mechanisches oder thermisches Schwächen der Zugglieder zu erzeugen und zum Ausbau der freien Ankerlänge die Zugglieder an der Sollbruchstelle mittels Aufbringen entsprechender Kräfte am Ankerkopf abzureissen (vgl. z.B. die
Weiter sind Verfahren bekannt, die die Trennung der Zugglieder durch Erwärmen bzw. Schmelzen mittels eines aluminothermischen Reaktionsgemisches bewirken (vgl. z.B. die
Aus der Patentschrift
Im Weiteren verläuft das Kabel zur Energieversorgung der Induktionsspule zwischen den als Zuggliedern dienenden Litzen und kann ebenfalls leicht beschädigt werden. Zudem sind die Hohlräume zwischen den Litzen und dem Sammelhüllrohr im Bereich der Trennstelle nicht luftseitig abgedichtet, so dass in die freie Ankerlänge Lfr eindringendes Wasser sich im Bereich der Trennstelle ansammeln kann. Dadurch wird das Erwärmen der Litzen infolge dauernder Abkühlung durch die Aufheizung und Verdampfung des Wassers praktisch verunmöglicht oder zumindest so lange verzögert, bis das Wasser restlos verdampft ist. (Die Litzen funktionieren somit ähnlich wie die Heizstäbe eines Tauchsieders zur Erwärmung von Wasser.)Furthermore, the cable runs to the power supply of the induction coil between serving as tension members strands and can also be easily damaged. In addition, the cavities between the strands and the collecting duct are not sealed air-side in the region of the separation point, so that in the free anchor length L fr penetrating water can accumulate in the region of the separation point. As a result, the heating of the strands due to continuous cooling by the heating and evaporation of the Water practically impossible or at least delayed until the water has evaporated completely. (The strands thus function in a similar way to the heating rods of an immersion heater to heat water.)
Auch aus der europäischen Patentanmeldung
Der Anmelder hat sich unter Bezugnahme auf das ältere Patent
Aufgabe der vorliegenden Erfindung ist es, die bekannten Vorrichtungen und Verfahren so zu verbessern, dass das Zugglied eines Ankers auf einfachere und zuverlässigere Weise trennbar ist.Object of the present invention is to improve the known devices and methods so that the tension member of an anchor is separable in a simpler and more reliable manner.
Diese Aufgabe wird durch eine Vorrichtung gemäss Anspruch 1 und ein Verfahren gemäss dem unabhängigen Verfahrensanspruch gelöst. Die weiteren Ansprüche geben bevorzugte Ausführungsformen der erfindungsgemässen Vorrichtung und des erfindungsgemässen Verfahrens sowie einen vorspannbaren Anker mit einer erfindungsgemässen Vorrichtung an.This object is achieved by a device according to claim 1 and a method according to the independent method claim. The further claims give preferred embodiments of the inventive device and the inventive method and a prestressable anchor with an inventive device.
Der Erfindung liegt die Erkenntnis zugrunde, dass entgegen der Lehre gemäss der
Die Erfindung wird weiter an bevorzugten
Ausführungsbeispielen unter Bezugnahme auf Figuren erläutert. Es zeigen:
-
Fig. 1 einen schematischen Schnitt durch eine Baugrube mit einem Anker ausgestattet mit einer Trennvorrichtung zum Trennen der Zugglieder an einer vorbestimmten Trennstelle; -
Fig. 2 einen Längsschnitt der Trennvorrichtung gemässFig. 1 , die gemäss einem ersten Ausführungsbeispiel am Ende des Sammelhüllrohres der freien Ankerlänge Lfr angebracht ist; -
Fig. 3 eine Vorderansicht einer Distanzscheibe für eine Trennvorrichtung gemässFig. 1 ; -
Fig. 4 einen Querschnitt der Trennvorrichtung gemässFig. 1 in der inFig. 2 mit I-I bezeichneten Schnittebene; -
Fig. 5 den Verlauf der relativen Festigkeit von Spannstahldraht in Funktion der Temperatur; -
Fig. 6 einen Längsschnitt der Trennvorrichtung gemässFig. 1 , bei welchem gemäss einem zweiten Ausführungsbeispiel das Ende des Sammelhüllrohres der freien Ankerlänge Lfr als Trägerrohr dient; -
Fig. 7 einen Schnitt durch die Trennvorrichtung in der inFig. 6 mit II-II bezeichneten Schnittebene; -
Fig. 8 die Ansicht des Distanzzapfenes für die Trennvorrichtung gemässFig. 6 , der die Verfüllung im Bereich der Trennstelle beidseits abschliesst; -
Fig. 9 einen Längsschnitt der Trennvorrichtung gemässFig. 1 , die gemäss einem dritten Ausführungsbeispiel am Ende des Sammelhüllrohres der freien Ankerlänge Lfr angebracht ist und mit Injektionsmaterial verfüllt ist; und -
Fig. 10 einen Schnitt durch die Trennvorrichtung in der inFig. 9 mit III-III bezeichneten Schnittebene.
Embodiments explained with reference to figures. Show it:
-
Fig. 1 a schematic section through a pit with an anchor equipped with a separator for separating the tension members at a predetermined separation point; -
Fig. 2 a longitudinal section of the separator according toFig. 1 , which is mounted according to a first embodiment at the end of the collecting duct of the free anchor length L fr ; -
Fig. 3 a front view of a spacer for a separator according toFig. 1 ; -
Fig. 4 a cross section of the separator according toFig. 1 in the inFig. 2 sectional plane designated II; -
Fig. 5 the course of the relative strength of prestressing steel wire as a function of temperature; -
Fig. 6 a longitudinal section of the separator according toFig. 1 in which according to a second embodiment, the end of the collecting tube of the free anchor length L fr serves as a carrier tube; -
Fig. 7 a section through the separator in the inFig. 6 sectional plane designated II-II; -
Fig. 8 the view of the spacer pin for the separator according toFig. 6 , which closes the filling in the area of the separation point on both sides; -
Fig. 9 a longitudinal section of the separator according toFig. 1 , which is mounted according to a third embodiment at the end of the collecting duct of the free anchor length L fr and filled with injection material; and -
Fig. 10 a section through the separator in the inFig. 9 III-III cutting plane.
Die Zugglieder 9 jedes Ankers 5 sind beispielsweise jeweils als siebendrähtige Spannstahllitze ausgebildet und weisen eine verbundlos durch ein Sammelhüllrohr 10 geführte freie Ankerlänge (Lfr) 7 und eine mittels Zementmörtel 11 kraftübertragend mit dem Baugrund 3 in Verbund gebrachte Verankerungslänge (Lv) 8 auf.The
An der Trennstelle 12 am Übergang der freien Ankerlänge (Lfr) 7 zur Verankerungslänge (Lv) 8 ist eine Trennvorrichtung 13 zum Trennen der Zugglieder 9 in den Anker 5 integriert.At the
Ein Kabel 18 zur Energieversorgung der Trennvorrichtung 13 verläuft ausserhalb des Sammelhüllrohrs 10 und ist an diesem befestigt. Die Injektionsleitung, durch welche der Zementmörtel zur Verankerung hindurchleitbar ist, verläuft ebenfalls ausserhalb des Sammelhüllrohrs 10 (nicht dargestellt). Beim Anbringen des Ankers werden Injektionsleitung und Kabel 18 zusammen am Sammelhüllrohr 10 befestigt und in das Bohrloch 4 eingefügt.A
Das Trägerrohr 15 ist starr ausgebildet, um ein Verschieben der Induktionsspule 16 relativ zu den Zuggliedern 9 und eine dadurch resultierende etwaige Beschädigung zu vermeiden, und aus einem Material gefertigt, das elektrisch isolierend und nicht-ferromagnetisch ist. Aufgrund der Starrheit des Trägerrohrs 15 wird u. a. verhindert, dass die nach dem Einbau des Ankers auftretenden Kräfte das Trägerrohr 15 zumindest über den Bereich der Induktionsspule 16 verformen. Als Material für das Trägerrohr 15 eignet sich z.B. Glasfasermaterial, PE, PP oder PVC.The
Die Trennvorrichtung 13 ist im Wesentlichen zentrisch im Bohrloch 4 angeordnet und der Hohlraum zwischen dem rückseitigen Ende der Trennvorrichtung 13 und dem Baugrund 3 ist mittels Zementmörtel 11 verfüllt.The separating
Die Induktionsspule 16 wird im Betrieb über das Elektrokabel 18 mit Strom höherer Frequenz versorgt, um die Zugglieder 9 induktiv bis zum Bruch zu erwärmen.The
Die Höhlräume zwischen dem Trägerrohr 15 und den Zuggliedern 9 sind mit einer Verfüllung 17 ausgefüllt. U.a. folgende Materialien eignen sich als Verfüllung 17: Zement-WasserGemisch mit etwaiger Zugabe eines oder mehrerer Zusatzmittel, wie z.B. Treibmittel, Verflüssiger und Abbindebeschleuniger, Mörtel auf Kunststoffbasis mit thermisch isolierenden Zuschlagstoffen, Kitt, etc.The cavities between the
Die Verfüllung 17 hat verschiedene Wirkungen:
Die Verfüllung 17 bewirkt eine thermische Isolation jedes einzelnen Zuggliedes 9, sodass die gleichmässige Erwärmung ohne Abstrahlung oder Aufnahme vonAnstrahlungsenergie benachbarter Zugglieder 9 sichergestellt ist.Sind die Zugglieder 9als Litzen 14 ausgebildet, ist gewährleistet, dass die Drähte der einzelnenLitzen 14 und dieLitzen 14 insgesamt gleich schnell erwärmt werden.Die Verfüllung 17 bewirkt eine minimale Verankerung der Zugglieder 9 luftseits derTrennstelle 12.Bei Litzen 14als Zugglieder 9 werden die zuerst abreissenden Drähte der einzelnenLitzen 14 sich leicht verzögert erst dann in Bewegung setzen, wenn mehrere bzw. alle Drähte undLitzen 14 getrennt sind. Die Verankerung ist insbesondere dann wirksam, wenn sich ein möglichst grosser Teil des Trägerrohrs 15 luftseits der Trennstelle 12 befindet. Wie inFig. 2 ersichtlich, ist zu diesem Zweck dieWicklung 16 seitlich versetzt zur Mitte desTrägerrohrs 15 angeordnet.Durch das Distanzelement 20 sowie die Verfüllung 17ist das Trägerrohr 15 abgedichtet, sodass eine Ansammlung von Wasser bei der Trennstelle 12 vermieden ist. Wasser ist nebst einer Verhinderung einer etwaigen Korrosion u.a. auch deshalb zu vermeiden, weiles die Zugglieder 9 beim Erwärmungsvorgang derart kühlen kann, dass diese für eine Trennung nicht mehr genügend erhitzt werden.Durch das Distanzelement 20 sowie die Verfüllung 17 des Trägerrohres 15 ist diefreie Ankerlänge L fr 7 gegen dasEindringen von Zementmörtel 11 während dem Ausinjiziernder Verankerungsstrecke L v 8 abgedichtet. Dadurch ist verhindert, dass sich indie freie Ankerlänge 7eindringender Zementmörtel 11 an den Litzen festsetzen und deren Herausziehen nach der Trennung erheblich erschweren oder ganz verunmöglichen kann.
- The backfilling 17 causes a thermal insulation of each
individual tension member 9, so that the uniform heating without radiation or absorption of radiation energy ofadjacent tension members 9 is ensured. Are thetension members 9 formed asstrands 14, it is ensured that the wires of theindividual strands 14 and thestrands 14 are heated at the same speed. - The backfilling 17 causes a minimal anchoring of the
tension members 9 on the air side of theseparation point 12. Instrands 14 astension members 9, the first tearing wires of theindividual strands 14 are only slightly delayed then set in motion when several or all wires andstrands 14 are separated , The anchoring is particularly effective when the largest possible part of thesupport tube 15 is located on the air side of theseparation point 12. As inFig. 2 can be seen, the winding 16 is laterally offset from the center of thesupport tube 15 for this purpose. - By the
spacer 20 and the filling 17, thesupport tube 15 is sealed, so that an accumulation of water at theseparation point 12 is avoided. Water is to be avoided in addition to preventing any corrosion, inter alia also because it can cool thetension members 9 during the heating process so that they are not heated enough for a separation. - By the
spacer element 20 and the filling 17 of thesupport tube 15, the freeanchor length L fr 7 is sealed against the penetration ofcement mortar 11 during the Ausinjiziern theanchoring section L v 8. This prevents that in thefree anchor length 7 penetratingcement mortar 11 settle on the strands and their extraction after separation can considerably complicate or completely impossible.
Aufgrund der thermischen Isolation der einzelnen Zugglieder 9 und der Verankerung der Zugglieder 9 luftseits der Trennstelle 12 ist insbesondere bei Zuggliedern 9 aus Litzen 14 ein synchrones Abreissen der einzelnen Drähte gewährleistet.Due to the thermal insulation of the
Wie
- Durchgang 20.1 bei N=1,
- Durchgang 20.2 und 20.5 bei N=2,
- Durchgang 20.3, 20.5 und 20.7 bei N=3,
- Durchgang 20.3, 20.4, 20.6 und 20.7 bei N=4,
- Durchgang 20.1, 20.2, 20.4, 20.5 und 20.7 bei N=5,
- Durchgang 20.2-20.7 bei N=6,
- Durchgang 20.1-20.7 bei N=7.
- Passage 20.1 at N = 1,
- Passage 20.2 and 20.5 at N = 2,
- Passage 20.3, 20.5 and 20.7 at N = 3,
- Passage 20.3, 20.4, 20.6 and 20.7 at N = 4,
- Passage 20.1, 20.2, 20.4, 20.5 and 20.7 at N = 5,
- Passage 20.2-20.7 at N = 6,
- Passage 20.1-20.7 at N = 7.
Bei jeder Zahl N ergibt sich eine Drehsymmetrie, d.h. bei einer Drehung um den Winkel 360°/n kommen die mit einem Zugglied durchsetzten Durchgänge wieder zur Deckung, wobei n = 2 für N = 2, 4 oder 5; n = 3 für N = 3; n = 6 für N = 6 oder 7 und n = unendlich für N=1.Each number N gives a rotational symmetry, i. with a rotation through the angle 360 ° / n, the passages penetrated by a tension member come back to coincide, where n = 2 for N = 2, 4 or 5; n = 3 for N = 3; n = 6 for N = 6 or 7 and n = infinite for N = 1.
Natürlich ist die Anzahl der Durchgänge bei der Distanzscheibe 20 beliebig auf die beim Anker vorgesehene Anzahl N der Zugglieder anpassbar. Beispielsweise kann die Distanzscheibe 20 für Anker mit 8 - 12 Litzen oder 13 - 19 Litzen als Zugglieder ausgelegt sein.Of course, the number of passages in the
Die Wicklung 16 weist eine Anzahl Windungen auf, die im Bereich von 5 bis 50, vorzugsweise 10 bis 30 liegt. Die Wicklung wird auf dem Sammelhüllrohr 10 durch einen Schrumpfschlauch 23 fixiert. Das Elektrokabel 18 verläuft ausserhalb des Sammelhüllrohres 10 zum Ankerkopf 6 und ist dadurch gegen eine Beschädigung beim Vorspannen der Zugglieder 9 geschützt.The winding 16 has a number of turns, which is in the range of 5 to 50, preferably 10 to 30. The winding is fixed on the collecting
Die Hohlräume zwischen dem Sammelhüllrohr 10 und den Zuggliedern 9 sind mit einer Verfüllung 17 ausgefüllt.
Die Verfüllung 17 ist beidseits durch Distanzzapfen 21 begrenzt, die aus einem elastisch verformbaren Material, z.B. Gummi gefertigt sind.The cavities between the collecting
The filling 17 is bounded on both sides by
Das Sammelhüllrohr 10 wird mittels Stahlbändern 22, welche mit genügend grosser Kraft gespannt werden, lokal so zusammengedrückt, dass sich das Spiel zwischen den Zuggliedern 9 und dem Sammelhüllrohr 10 gegenüber dem Distanzzapfen 21 schliesst.The collecting
Das Ende des Sammelhüllrohres 10 ist zwecks Abdichtung der freien Ankerlänge 7 gegen den in die Verankerungslänge 8 injizierten Zementmörtel 11 mit einer heiss eingefüllten Bitumenverfüllung 24 ausgegossen, die mit Stahlbändern 22 gegenüber dem Sammelhüllrohr 10 fixiert wird.For the purpose of sealing the
Die Wicklung 16 bestehend aus Windungen des Elektrokabels 18 sitzt auf einem Trägerrohr 15, welches mit einem Schrumpfschlauch 23 gegenüber dem Sammelhüllrohr 10 und der die Verankerungslänge 8 bildenden Teil der Zugglieder 14 fixiert wird. Die Hohlräume zwischen dem Trägerrohr 15 und den Zuggliedern 9 werden direkt durch den in die Verankerungslänge 8 injizierten Zementmörtel 11 ausgefüllt. Beim Einbau des Ankers 5 ist demnach das Trägerrohr 15 am luftseitigen Ende abgedichtet, jedoch am bergseitigen Ende offen, so dass das Injektionsmaterial 11 beim Injizieren in das Trägerrohr 15 eindringen und dieses verfüllen kann.The winding 16 consisting of turns of the
So wie durch die Verfüllung 17 und den Distanzelementen 20, 21 beim ersten und zweiten Ausführungsbeispiel ist hier durch die Verfüllung 24 das Trägerrohr 15 derart auf der dem vorspannbaren Teil der Zugglieder 9 zugewandten Seite der Trennstelle 12 abgedichtet, dass einerseits ein Durchtritt von Wasser und andererseits ein Durchtritt von Injektionsmaterial 11 verhindert sind. Dadurch ist gewährleistet, dass einerseits das Injektionsmaterial 11 beim Injizieren nicht zum vorspannbaren Teil der Zugglieder 9 gelangt und andererseits kein Wasser von aussen zur Trennstelle 12 vordringen kann und so ein effizientes Erwärmen der Zugglieder 9 ermöglicht wird.As well as by the
Nachfolgend sind weitere Erläuterungen gegeben, die sich nicht speziell auf ein einzelnes Ausführungsbeispiel beziehen.In the following, further explanations are given, which do not relate specifically to a single embodiment.
Vorteilhafterweise weist die jeweilige Litze 14 des Zuggliedes 9 eine Seele auf, um welche Drähte gewunden sind, deren Durchmesser kleiner als der Durchmesser der Seele ist. Dadurch ist gewährleistet, dass beim Erwärmungsvorgang die Seele, welche zusätzlich durch die sie umgebenden Drähte erwärmt wird, nicht als erste reisst, sondern alle Drähte der Litze 14 gleichzeitig getrennt werden.Advantageously, the
Die Zugglieder 9 der vorgespannten Boden- und Felsanker 5 werden in der Regel auf ca. 60 % der Bruchkraft vorgespannt. Da ein Anker 5 über längere Zeit im Boden eingelassen sein kann, ist für den Ausbau mittels der Trennvorrichtung 13 sicherzustellen, dass die Zugglieder 9 noch genügend vorgespannt sind. Die Vorspannung ist so gewählt, dass beim Erwärmvorgang durch die Induktionsspule 16 das jeweilige Zugglied 9 mit einer Kraft vorgespannt ist, die mindestens 10 %, bevorzugt mindestens 25 % und besonders bevorzugt mindestens 50 % der Bruchkraft des Zugglieds 9 bei 0 Grad Celsius entspricht.The
Aufgrund einer genügenden Vorspannung ist es möglich, die Zugglieder 9 bei relativ moderaten Temperaturen zu trennen, die unterhalb des Schmelzpunktes liegen und typischerweise unter 700 Grad Celsius und sogar unter 600 Grad Celsius sind. Wird die Festigkeit des Zuggliedes 9 durch Erwärmen unter die im Zugglied 9 anliegende Spannung abgesenkt, reisst dieses. Aufgrund der Spannung wird der abgerissene Teil des Zugglieds 9 aus dem Ankerkopf herausspringen. Aus Sicherheitsgründen wird daher der Ankerkopf beim Erwärmvorgang mit einer Haube abgedeckt, um die Zugglieder 9 nach dem Bruch aufzufangen.Due to sufficient preload it is possible to separate the
Somit braucht die Trennvorrichtung 13 nicht so ausgelegt zu werden, dass sie eine Erwärmung über die Curie-Temperatur (für Fe 768°C) hinweg bis zum Schmelzpunkt gestattet, wie dies bei der Vorrichtung gemäss
Als Speisegerät zur Energieversorgung der Induktionsspule 16 dient ein statischer Frequenzumformer, der einen Lastschwingkreis mit der Wicklung 16 als Induktion aufweist. Der Lastschwingkreis ist als Parallelschwingkreis aufgebaut, der als Elemente Leistungskondensätoren sowie die über das Kabel 18 angeschlossene Wicklung 16 aufweist. Kapazität und Induktivität dieser Elemente bestimmen die Arbeitsfrequenz. Der Lastschwingkreis ist an eine Stromquelle angeschlossen, die einen an das übliche Stromnetz anschliessbaren Haupttransformator, einen Gleichrichter, einen Chopper und einen Glättungsteil enthält. Der Lastschwingkreis ist an einer H-Brücke angeschlossen, welche mittels des Choppers geregelt wird.As a power supply to the power supply of the
Die Ausgestaltung des Speisegeräts in Form einer Schaltung mit elektronischen Komponenten erlaubt einen kompakten und relativ leichten Aufbau. So ist der statische Frequenzumformer wesentlich leichter als ein dynamischer Frequenzumformer aufbaubar und wiegt typischerweise weniger als 100 kg und vorzugsweise weniger als 50 kg. Auch ist durch die Integration der jeweilig verwendeten Induktionsspule 16 und des verwendeten Kabels 18 in den Schwingkreis das Magnetfeld optimierbar, welches zum Erwärmen der Zugglieder 9 verwendet wird.The design of the power supply in the form of a circuit with electronic components allows a compact and relatively lightweight construction. Thus, the static frequency converter is much lighter than a dynamic frequency converter can be built and typically weighs less than 100 kg, and preferably less than 50 kg. Also, by the integration of the respective used
Mittels des statischen Frequenzumformers kann die Induktionsspule 16 mit einem Strom beaufschlagt werden, der über 2.5 A, vorzugsweise über 5 A und besonders bevorzugt über 10 A liegt und der eine Frequenz f von über 1 kHz und vorzugsweise über 10 kHz aufweist. Typischerweise liegt die Frequenz im Bereich von 30 - 50 kHz. Die vom Frequenzumformer abgegebene Leistung ist über 1 kW und vorzugsweise über 3 kW, z.B. bei 5 kW.By means of the static frequency converter, the
Die Heizleistung, welche mittels der Induktionsspule 16 in den Zuggliedern 9 induziert wird, nimmt mit zunehmender Frequenz f des Stroms zu. Andererseits verringert sich aufgrund des Skineffektes die Eindringtiefe des Stromes, wenn die Frequenz f zunimmt.The heating power, which is induced by means of the
Das Kabel 18 ist mindestens 5 m und bevorzugt mindestens 10 m lang und ist ein handelsübliches Kabel, z.B. eines mit mehr als zwei Adern und/oder mit Adern mit jeweils einem Querschnitt von mindestens 1.5 mm2. Die jeweilige Ader kann entweder als Einzeldraht oder als Litze ausgebildet sein. Wird ein Kabel 18 mit vier Adern verwendet, so werden vorteilhafterweise die jeweils beiden einander gegenüberliegenden Adern miteinander verbunden.The
Überraschenderweise wurde festgestellt, dass sich ein handelsübliches Kabel 18 nicht merklich erwärmt, wenn der Strom mit hoher Frequenz hindurchgeleitet wird. Es sind somit keine teuren Spezialkabel für die Energiespeisung der Wicklung 16 erforderlich.Surprisingly, it has been found that a
Die hier dargestellte Trennvorrichtung 13 ist zum Ausbau (Rückbau) mindestens der freien Ankerlänge der Zugglieder von vorgespannten Boden- und Felsankern verwendbar, wie sie z.B. in der Schweizer Norm "SIA 267 Geotechnik" und "EN 1537 Verpressanker" beschrieben sind.The
Ausgehend von der vorausgehenden Beschreibung von bevorzugten Ausführungsbeispielen sind dem Fachmann abgewandelte Ausführungen zugänglich, ohne den Bereich der Erfindung wie in den Ansprüchen definiert zu verlassen.Starting from the foregoing description of preferred embodiments, modifications adapted to those skilled in the art are obtainable without departing from the scope of the invention as defined in the claims.
Anstelle einer Verfüllung 17, die das Trägerrohr 15 vollständig ausfüllt, ist es auch möglich, eine Dichtung jeweils an den beiden Enden des Trägerrohrs 15 vorzusehen und den Hohlraum zwischen den beiden Dichtungen ungefüllt zu lassen. Die sich im Hohlraum befindende Luft wirkt dann für die einzelnen Zugglieder thermisch isolierend. Als Dichtung kann z.B. ein Element in Form des in
Anstelle einer einlagigen Wicklung 16 ist auch eine zweilagige Wicklung denkbar, wobei die Trennvorrichtung auch bei dieser Ausführungsform nach wie vor schlank in der seitlichen Ausdehnung bleibt.Instead of a single-layer winding 16, a two-layer winding is also conceivable, with the separation device remaining slender in its lateral extent, even in this embodiment.
Die Trennvorrichtung ist nebst Anker mit einer Verankerungslänge u.a. auch für solche ohne Verankerungslänge, insbesondere Druckrohranker verwendbar.The separator is in addition to anchor with an anchoring length u.a. also suitable for those without anchoring length, in particular pressure tube anchor.
Claims (15)
- Device for an at least partially removable anchor (5) that is anchorable in a foundation ground (3) by injecting cement mortar, comprisingat least one tension member (9) with a pretensionable part (7) andan induction coil (16) surrounding the tension member for separating the tension member at a separating point (12) by induction heating, whereinas seen in cross-section, the area between the induction coil (16) and the separating point (12) is free from an electrically conducting metal tube, and wherein the induction coil (16) is arranged on a carrier tube (15), characterised in thatthe carrier tube (15) is sealed on the side of the separating point (12) facing towards the pretensionable part (7) of the tension member by a seal (17, 20, 21; 24), which is located at a distance from the free end of the pretensionable part (7), so that the seal is located in the foundation ground (3) when the anchor is built in, and which seals the pretensionable part (7) against the ingress of cement mortar while the latter is being injected.
- Device according to claim 1, wherein the carrier tube (15) is rigid and preferably made of a synthetic material, in particular PE, PP, or PVC, or of glass fibre material.
- Device according to one of the preceding claims, comprising a common sheath (10), in which the pretensionable part (7) of the tension member (9) extends, one of the ends of the sheath (10) preferably serving as the carrier tube for the induction coil (16).
- Device according to one of the preceding claims, wherein the carrier tube (15) is sealed (17, 20, 21; 11, 24) on both sides of the separating point (12) in order to avoid an accumulation of water.
- Device according to one of the preceding claims, wherein the carrier tube (15) is provided with a filling (17; 11) that seals the separating point (12) and preferably insulates the tension member (9) thermally and/or anchors it to the carrier tube (15).
- Device according to one of the preceding claims, wherein the ratio of the external diameter (Da) of the induction coil (16) to the internal diameter (Di) of the induction coil is equal to at most 1.5 and preferably to at most 1.25 and/or the winding of the induction coil (16) is at most two-layered and preferably single-layered.
- Device according to one of the preceding claims, comprising a cable (18) for the energy supply of the induction coil (16), which cable runs outside the carrier tube (15) in order to avoid damages of the cable (18) when the tension member (9) is pretensioned.
- Device according to claim 7, wherein the cable (18) is seamlessly wound around the carrier tube (15) to form the induction coil (16).
- Device according to one of claims 7 to 8, wherein the cable (18) has more than two conductors and/or conductors having a cross-sectional area of at least 1.5 mm2 each.
- Device according to one of the preceding claims, comprising a frequency converter for supplying the induction coil (16) with current, which frequency converter allows the generation of a frequency of more than 1 kHz and/or is a static frequency converter.
- Device according to claim 10, wherein, for generating an alternating current, the frequency converter includes an oscillating circuit, in which the induction coil (16) can be integrated.
- Device according to one of the preceding claims, comprising multiple tension members (9), wherein at least one spacer (20; 21) is received in the carrier tube (15), which spacer has passages (20.1 - 20.7; 21.1 - 21.4) through which the tension members (9) extend, and wherein the passages (20.1 - 20.7; 21.1 - 21.4) are preferably arranged such that a rotational symmetry results when seen in the cross-section of the spacer (20; 21).
- Device according to one of the preceding claims, wherein the at least one tension member (9) is in the form of a strand (14) having a core around which wires are wound whose diameter is smaller than the diameter of the core.
- Pretensionable anchor (5) comprising a device according to one of the preceding claims.
- Method for at least partially removing an anchor (5) according to claim 14 including at least one tension member (9) which is heated by means of an induction coil (16) in order to be separated, characterised in that
the tension member (9) is pretensioned during the heating procedure with a force that corresponds to at least 10 %, preferably at least 25 %, and particularly preferably at least 50 % of the breaking force of the tension member (9) at 0 degrees Celsius.
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EP15192785.2A EP2998447B1 (en) | 2010-03-25 | 2010-03-25 | Method for at least partially removing an anchor |
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PCT/CH2010/000086 WO2011116483A2 (en) | 2010-03-25 | 2010-03-25 | Device for an at least partially removable anchor and method for at least partially removing an anchor |
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FR2274740A1 (en) * | 1975-06-27 | 1976-01-09 | Fischer Joachim | Extraction method for steel rod ground anchors - rupture zone in rod adjacent to anchor block is formed by heating |
CH603919A5 (en) | 1976-04-02 | 1978-08-31 | Losinger Ag | Releasing free section of tie anchor |
JPS53101805A (en) * | 1977-02-17 | 1978-09-05 | Isamu Ikeda | Method of removing anchor |
JPS58110719A (en) * | 1981-12-24 | 1983-07-01 | Chem Kurauto Kk | Drawing of earth anchor |
CH661079A5 (en) | 1983-01-13 | 1987-06-30 | Dyckerhoff & Widmann Ag | METHOD AND DEVICE FOR REMOVING THE FREE PART OF THE TENSION MEMBER OF A PRELOADED PRESSURE ANCHOR. |
CH681835A5 (en) * | 1992-08-17 | 1993-05-28 | Toni Baer | |
DE19500091C1 (en) * | 1995-01-04 | 1996-04-04 | Dyckerhoff & Widmann Ag | Predetermined rupture position prodn. on tensile member of insert anchor |
NL1015346C2 (en) * | 2000-05-31 | 2001-12-03 | Visser & Smit Bouw Bv | Removal method for free anchor length of grouted anchor sunk into the ground, involves heating free anchor length to form point of weakness |
JP2005248587A (en) * | 2004-03-04 | 2005-09-15 | Anderson Technology Kk | Method and device for fusion-cutting prestressing steel in ground anchor |
JP2007262880A (en) * | 2006-03-02 | 2007-10-11 | Ats & E Co Ltd | Device and method for cutting of tension member in buried anchor |
JP4910142B2 (en) * | 2006-10-05 | 2012-04-04 | 飛島建設株式会社 | High frequency induction heating anchor removal device |
JP5217054B2 (en) * | 2007-03-02 | 2013-06-19 | 住友電工スチールワイヤー株式会社 | Strand |
CH702926B9 (en) * | 2007-10-09 | 2011-12-30 | Stahlton Ag | Apparatus for an at least partially expandable anchor and method for at least partial expansion of an anchor. |
-
2010
- 2010-03-25 EP EP15192785.2A patent/EP2998447B1/en active Active
- 2010-03-25 EP EP10711318.5A patent/EP2550404B1/en active Active
- 2010-03-25 WO PCT/CH2010/000086 patent/WO2011116483A2/en active Application Filing
Non-Patent Citations (1)
Title |
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None * |
Also Published As
Publication number | Publication date |
---|---|
WO2011116483A3 (en) | 2012-03-08 |
EP2550404A2 (en) | 2013-01-30 |
WO2011116483A2 (en) | 2011-09-29 |
EP2998447B1 (en) | 2017-10-04 |
EP2998447A1 (en) | 2016-03-23 |
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