EP0196451B1 - Tension element for a rock bolt or the like - Google Patents

Tension element for a rock bolt or the like Download PDF

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Publication number
EP0196451B1
EP0196451B1 EP86102426A EP86102426A EP0196451B1 EP 0196451 B1 EP0196451 B1 EP 0196451B1 EP 86102426 A EP86102426 A EP 86102426A EP 86102426 A EP86102426 A EP 86102426A EP 0196451 B1 EP0196451 B1 EP 0196451B1
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EP
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Prior art keywords
tension member
member according
steel wires
central cavity
synthetic resin
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EP86102426A
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German (de)
French (fr)
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EP0196451A1 (en
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& Widmann Aktiengesellschaft Dyckerhoff
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Dyckerhoff and Widmann AG
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Priority to AT86102426T priority Critical patent/ATE36893T1/en
Publication of EP0196451A1 publication Critical patent/EP0196451A1/en
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    • E—FIXED CONSTRUCTIONS
    • E21—EARTH DRILLING; MINING
    • E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
    • E21D21/00—Anchoring-bolts for roof, floor in galleries or longwall working, or shaft-lining protection
    • E21D21/0026—Anchoring-bolts for roof, floor in galleries or longwall working, or shaft-lining protection characterised by constructional features of the bolts
    • E21D21/0033—Anchoring-bolts for roof, floor in galleries or longwall working, or shaft-lining protection characterised by constructional features of the bolts having a jacket or outer tube
    • E—FIXED CONSTRUCTIONS
    • E21—EARTH DRILLING; MINING
    • E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
    • E21D21/00—Anchoring-bolts for roof, floor in galleries or longwall working, or shaft-lining protection
    • E21D21/0026—Anchoring-bolts for roof, floor in galleries or longwall working, or shaft-lining protection characterised by constructional features of the bolts
    • E21D21/006—Anchoring-bolts made of cables or wires

Definitions

  • the invention relates to a tension member consisting of a bundle of steel wires for a rock bolt or the like, and to a method for its production.
  • Rock bolts essentially have the task of securing rock packs against displacements as early as possible when opening cavities in a naturally occurring mountain range with fissures.
  • a typical type of stress of such rock bolts is a combined tensile and shear stress with large shear paths.
  • Tension members that are used as rock bolts must therefore have a high work capacity in order to be able to take part in the large bends.
  • the stiffness of a solid cross-section, as z. B. has a steel rod is an obstacle.
  • tubular tension members made of steel with a thin wall, the z. B. be pressed by hydraulic pressure against the borehole wall and transmit the force by friction.
  • Tubular tension members of this type have an even lower shear resistance than rod-shaped anchors; however, they allow a greater shear path since the cavity of the borehole remains essentially free.
  • Tubular tension members have no corrosion protection and cannot be produced in any length. Anchoring bodies cannot be attached to their smooth outer surface.
  • a rock anchor is also known, the tension member of which has a defined flexibility zone in the middle part, in which the tension member made of stainless, austenitic steel has a smaller cross section than in the end parts (DE-C-3 320 460).
  • the tension member can also consist of a bundle of steel wires. In order to prevent the tension member from bonding with the adhesive filling the borehole in this compliance zone, it is surrounded by a coating there.
  • a thread is provided at the air-side end of the tension member for anchoring by means of a nut.
  • the invention has for its object to provide a tension member for a rock bolt, which can be produced economically in any length, has a high work capacity to be able to take strong bends and also gives the possibility of anchoring body, for. B. in the form of nuts or the like.
  • this object is achieved in a tension member consisting of a bundle of steel wires in that the steel wires while leaving a central cavity in a tubular body made of a hardening, plastic material, for. B. synthetic resin, are embedded and the tubular body has a profile on its outer surface.
  • the steel wires are expediently arranged radially symmetrically in the tubular body, which itself advantageously has a circular cross section.
  • the central cavity also expediently has a circular cross section.
  • the profiling of the tension member on its outer surface which also on an envelope of the tubular body, for. B. can be formed from a thermoplastic resin, is used, in particular if it is designed as a screw thread, for fixing the tension member on the head by means of an appropriately designed anchoring body.
  • a bracing in relation to the surface of the underground cavity is generally sufficient, since only a force-fit connection to this surface is usually required for the rock bolt to be effective.
  • the central cavity of the tension member if it is still open after it has been installed in the borehole, allows control of possible shear movements or the insertion of measuring probes. It can also be used to inject a hardening material into the borehole or to vent if hardening material is injected in another way. It is expedient if at least in partial areas of the length of the tension member along at least one surface line from the central cavity outward openings are provided, which can be valve-shaped.
  • the profiling of the outer surface of the tension member can also only extend over partial regions of its length, while regions with a smooth outer surface are provided between the regions provided with a profiling.
  • the areas provided with the profiling are only as long as required for anchoring the occurring forces and a smooth area is arranged between each of the profiled areas in which no bond can form between the tension member and the hardening material filling the remaining part of the borehole, moreover allows a greater steel length to be activated when the tension member is bent as a result of shear stress. This corresponds in a special way to the requirements for rock bolts, which are supposed to hold smaller layers of layers together, for which purpose intermediate anchors separated from each other by bondless areas are particularly favorable.
  • a tension member according to the invention also provides excellent protection against corrosion, since the steel wires are completely embedded in synthetic resin; this is especially true when it is surrounded by a covering. Tension members of this type can therefore also be used as permanent anchors and thus promote the path to a single-shell expansion of the underground cavity.
  • the invention relates to a method for producing such a tension member.
  • an inner tube made of thermoplastic synthetic resin, e.g. B. PE.
  • the steel wires are then fed along its outer surface and pressed into its surface. These steel wires are then through a plastic, hardening mass, for. B. encased a polyester resin.
  • B. from a thermoplastic material, such as PVC, existing covering applied.
  • the particular advantage of the method is that it is possible in this way to produce a tension member for a rock bolt in a continuous process, which can be cut to any length and, if the profile is formed on its outer surface as a screw thread, also screwing one Anchoring body allowed at any point.

Abstract

A tension member for use as a rock anchor or the like has a plurality of steel wires embedded in a tubular member with a central bore and formed of a hardenable plastics material, such as a synthetic resin. The outer surface of the tubular member is profiled such as in the manner of a screw thread so that an anchor member can be threaded on to the tubular member. The steel wires are arranged symmetrically around the axis of the tubular member for carrying the load transmitted by the tension member. If there is a displacement of the rock anchored by the tension member then both the tension and shearing stresses acting on the wires can cause individual wires to be displaced from the tubular member into its central bore. As a result, the flexibility of the tension member is increased and the most highly stressed wires can move out of the tubular member into its central bore.

Description

Die Erfindung betrifft ein aus einem Bündel von Stahldrähten bestehendes Zugglied für einen Felsbolzen oder dergleichen sowie ein Verfahren zu dessen Herstellung.The invention relates to a tension member consisting of a bundle of steel wires for a rock bolt or the like, and to a method for its production.

Felsbolzen haben im wesentlichen die Aufgabe, beim Auffahren von Hohlräumen in einem natürlich anstehenden Gebirge mit Klüftungen Felspakete zu einem möglichst frühen Zeitpunkt gegen Verschiebungen zu sichern. Eine typische Beanspruchungsart solcher Felsbolzen ist eine kombinierte Zug- und Scherbeanspruchung mit großen Scherwegen. Zugglieder, die als Felsbolzen verwendet werden, müssen daher ein hohes Arbeitsvermögen aufweisen, um die großen Verbiegungen mitmachen zu können. Die Steifigkeit eines massiven Querschnitts, wie ihn z. B. ein Stahlstab hat, ist dafür ein Hindernis.Rock bolts essentially have the task of securing rock packs against displacements as early as possible when opening cavities in a naturally occurring mountain range with fissures. A typical type of stress of such rock bolts is a combined tensile and shear stress with large shear paths. Tension members that are used as rock bolts must therefore have a high work capacity in order to be able to take part in the large bends. The stiffness of a solid cross-section, as z. B. has a steel rod is an obstacle.

Bekannt sind auch rohrförmige Zugglieder aus Stahl mit dünner Wandung, die z. B. mittels hydraulischen Drucks gegen die Bohrlochwand gepreßt werden und durch Reibung die Kraft übertragen. Rohrförmige Zugglieder dieser Art haben einen noch geringeren Scherwiderstand als stabförmige Anker; sie erlauben aber einen größeren Scherweg, da der Hohlraum des Bohrloches im wesentlichen frei bleibt. Rohrförmige Zugglieder haben keinen Korrosionsschutz und sind nicht in beliebigen Längen herstellbar. An ihrer glatten Außenfläche lassen sich Verankerungskörper nicht anbringen.Also known are tubular tension members made of steel with a thin wall, the z. B. be pressed by hydraulic pressure against the borehole wall and transmit the force by friction. Tubular tension members of this type have an even lower shear resistance than rod-shaped anchors; however, they allow a greater shear path since the cavity of the borehole remains essentially free. Tubular tension members have no corrosion protection and cannot be produced in any length. Anchoring bodies cannot be attached to their smooth outer surface.

Schließlich ist auch ein Gebirgsanker bekannt, dessen Zugglied im Mittelteil eine definierte Nachgiebigkeitszone aufweist, in der das aus rostfreiem, austenitischem Stahl bestehende Zugglied einen geringeren Querschnitt hat als in den Endteilen (DE-C-3 320 460). In diesem Mittelteil kann das Zugglied auch aus einem Bündel von Stahldrähten bestehen. Um in dieser Nachgiebigkeitszone einen Verbund des Zugglieds mit dem das Bohrloch ausfüllenden Kleber zu verhindern, ist es dort von einer Beschichtung umgeben. Am luftseitigen Ende des Zugglieds ist zur Verankerung mittels einer Mutter ein Gewinde vorgesehen.Finally, a rock anchor is also known, the tension member of which has a defined flexibility zone in the middle part, in which the tension member made of stainless, austenitic steel has a smaller cross section than in the end parts (DE-C-3 320 460). In this middle part, the tension member can also consist of a bundle of steel wires. In order to prevent the tension member from bonding with the adhesive filling the borehole in this compliance zone, it is surrounded by a coating there. A thread is provided at the air-side end of the tension member for anchoring by means of a nut.

Der Erfindung liegt die Aufgabe zugrunde, ein Zugglied für einen Felsbolzen zu schaffen, das auf wirtschaftliche Weise in beliebigen Längen herstellbar ist, das ein hohes Arbeitsvermögen hat, um auch starke Verbiegungen mitmachen zu können und das darüber hinaus die Möglichkeit gibt, Verankerungskörper, z. B. in Form von Gewindemuttern oder dergleichen anbringen zu können.The invention has for its object to provide a tension member for a rock bolt, which can be produced economically in any length, has a high work capacity to be able to take strong bends and also gives the possibility of anchoring body, for. B. in the form of nuts or the like.

Nach der Erfindung wird diese Aufgabe bei einem aus einem Bündel von Stahldrähten bestehenden Zugglied dadurch gelöst, daß die Stahldrähte unter Belassung eines zentralen Hohlraumes in einen rohrförmigen Körper aus einem erhärtenden, plastischen Material, z. B. Kunstharz, eingebettet sind und der rohrförmige Körper an seiner Außenfläche eine Profilierung aufweist.According to the invention, this object is achieved in a tension member consisting of a bundle of steel wires in that the steel wires while leaving a central cavity in a tubular body made of a hardening, plastic material, for. B. synthetic resin, are embedded and the tubular body has a profile on its outer surface.

Durch Auflösen des für die Übertragung der Ankerkraft erforderlichen Stahlquerschnitts in eine Anzahl von um einen zentralen Hohlraum herum angeordneten Drähten mit Einzelquerschnitten mit kleinem Widerstandsmoment und deren Einbettung in ein Material, aus dem sie sich bei großer Scherbeanspruchung lösen können, wird die Biegsamkeit des gesamten Zuggliedes so erhöht, daß die bei einer kombinierten Scher- und Biegebeanspruchung auftretenden Knicke ausgerundet werden können. Dabei kann der bzw. können die am stärksten beanspruchte Draht bzw. Drähte sich aus dem Verbund mit dem rohrförmigen Körper lösen und in den zentralen Hohlraum ausweichen. Durch die gegenüber Stäben mit massivem Querschnitt und Rohren höhere Biegsamkeit wird vor allem bei solchen Bolzen der Einbau erleichtert, die in größerer Länge von kleinen Räumen aus eingebaut werden müssen, was bei der Auffahrung von Stollen, Tunnels oder dergleichen oft notwendig ist.By dissolving the steel cross-section required for the transmission of the anchor force into a number of wires arranged around a central cavity with individual cross-sections with a small section modulus and embedding them in a material from which they can be released under high shear stress, the flexibility of the entire tension member becomes so increases that the kinks occurring in a combined shear and bending stress can be rounded off. The wire or wires that are subjected to the greatest stress can be released from the composite with the tubular body and can escape into the central cavity. Due to the higher flexibility compared to bars with a solid cross-section and tubes, the installation is made easier, especially for bolts that have to be installed in greater lengths from small rooms, which is often necessary when driving up tunnels, tunnels or the like.

Zweckmäßig werden die Stahldrähte radialsymmetrisch in dem rohrförmigen Körper angeordnet, der selbst vorteilhaft kreisförmigen Querschnitt aufweist. Auch der zentrale Hohlraum hat zweckmäßig einen kreisförmigen Querschnitt.The steel wires are expediently arranged radially symmetrically in the tubular body, which itself advantageously has a circular cross section. The central cavity also expediently has a circular cross section.

Die Profilierung des Zuggliedes an seiner Außenfläche, die auch an einer Umhüllung des rohrförmigen Körpers, z. B. aus einem thermoplastischen Kunstharz, ausgebildet sein kann, dient, insbesondere dann, wenn sie als Schraubgewinde ausgebildet ist, zum Fixieren des Zuggliedes am Kopf mittels eines entsprechend ausgebildeten Verankerungskörpers. Hierfür reicht im allgemeinen eine Verspannung gegenüber der Oberfläche des unterirdischen Hohlraumes aus, da zur Wirksamkeit des Felsbolzens meist nur ein Kraftschluß zu dieser Oberfläche erforderlich ist.The profiling of the tension member on its outer surface, which also on an envelope of the tubular body, for. B. can be formed from a thermoplastic resin, is used, in particular if it is designed as a screw thread, for fixing the tension member on the head by means of an appropriately designed anchoring body. For this purpose, a bracing in relation to the surface of the underground cavity is generally sufficient, since only a force-fit connection to this surface is usually required for the rock bolt to be effective.

Der zentrale Hohlraum des Zugglieds erlaubt, sofern er nach dessen Einbau in das Bohrloch noch offen ist, eine Kontrolle eventueller Scherbewegungen oder das Einführen von Meßsonden. Er kann auch zum Injizieren eines erhärtenden Materials in das Bohrloch oder zum Entlüften verwendet werden, falls erhärtendes Material auf andere Weise injiziert wird. Dabei ist es zweckmäßig, wenn zumindest in Teilbereichen der Länge des Zugglieds entlang mindestens einer Mantellinie vom zentralen Hohlraum nach außen gerichtete Durchbrechungen vorgesehen sind, die ventilartig ausgebildet sein können.The central cavity of the tension member, if it is still open after it has been installed in the borehole, allows control of possible shear movements or the insertion of measuring probes. It can also be used to inject a hardening material into the borehole or to vent if hardening material is injected in another way. It is expedient if at least in partial areas of the length of the tension member along at least one surface line from the central cavity outward openings are provided, which can be valve-shaped.

Nach der Erfindung kann sich die Profilierung der Außenfläche des Zugglieds auch nur über Teilbereiche seiner Länge erstrecken, während zwischen den mit einer Profilierung versehenen Bereichen Bereiche mit glatter Außenfläche vorgesehen sind.According to the invention, the profiling of the outer surface of the tension member can also only extend over partial regions of its length, while regions with a smooth outer surface are provided between the regions provided with a profiling.

Wenn die mit der Profilierung versehenen Bereiche nur so lang sind, wie jeweils zur Verankerung der auftretenden Kräfte erforderlich und zwischen den profilierten Bereichen jeweils ein glatter Bereich angeordnet ist, in dem sich kein Verbund zwischen dem Zugglied und dem den übrigen Teil des Bohrloches ausfüllenden erhärtenden Material ausbilden kann, erlaubt üieser bei einer Verbiegung des Zugglieds infolge einer Scherbeanspruchung die Aktivierung einer größeren Stahllänge. Dies entspricht in besonderer Weise den Anforderungen an Felsbolzen, die kleinere Schichtpakete zusammenhalten sollen, wozu durch verbundfreie Bereiche voneinander getrennte Zwischenverankerungen besonders günstig sind.If the areas provided with the profiling are only as long as required for anchoring the occurring forces and a smooth area is arranged between each of the profiled areas in which no bond can form between the tension member and the hardening material filling the remaining part of the borehole, moreover allows a greater steel length to be activated when the tension member is bent as a result of shear stress. This corresponds in a special way to the requirements for rock bolts, which are supposed to hold smaller layers of layers together, for which purpose intermediate anchors separated from each other by bondless areas are particularly favorable.

Schließlich gewährt ein Zugglied nach der Erfindung auch einen ausgezeichneten Korrosionsschutz, da die Stahldrähte vollständig in Kunstharz eingebettet sind; dies gilt vor allem dann, wenn dieses noch dazu von einer Umhüllung umgeben ist. Zugglieder dieser Art können deshalb auch als Daueranker eingesetzt werden und fördern so den Weg zu einem einschaligen Ausbau des unterirdischen Hohlraums.Finally, a tension member according to the invention also provides excellent protection against corrosion, since the steel wires are completely embedded in synthetic resin; this is especially true when it is surrounded by a covering. Tension members of this type can therefore also be used as permanent anchors and thus promote the path to a single-shell expansion of the underground cavity.

Gegenstand der Erfindung ist schließlich noch ein Verfahren zum Herstellen eines solchen Zuggliedes. Dabei wird in einem kontinuierlichen Verfahren zunächst ein den zentralen Hohlraum bildendes Innenrohr aus thermoplastischem Kunstharz, z. B. PE, hergestellt. Noch vor dem Aushärten des Materials des Innenrohres werden sodann entlang seiner Außenfläche die Stahldrähte zugeführt und in seine Oberfläche eingedrückt. Diese Stahldrähte werden danach durch eine plastische, erhärtende Masse, z. B. ein Polyesterharz, eingehüllt. Schließlich wird entweder im Zuge dieses Verfahrens oder in einem eigenen nachgeschalteten Verfahrensschritt eine z. B. aus einem thermoplastischen Material, wie PVC, bestehende Umhüllung aufgebracht.Finally, the invention relates to a method for producing such a tension member. In a continuous process, an inner tube made of thermoplastic synthetic resin, e.g. B. PE. Before the material of the inner tube hardens, the steel wires are then fed along its outer surface and pressed into its surface. These steel wires are then through a plastic, hardening mass, for. B. encased a polyester resin. Finally, either in the course of this process or in a separate downstream process step. B. from a thermoplastic material, such as PVC, existing covering applied.

Der besondere Vorteil des Verfahrens liegt darin, daß es auf diese Weise gelingt, in einem kontinuierlichen Verfahren ein Zugglied für einen Felsbolzen herzustellen, das auf beliebige Längen geschnitten werden kann und, wenn die Profilierung an seiner Außenfläche als Schraubgewinde ausgebildet ist, außerdem das Aufschrauben eines Verankerungskörpers an beliebigen Stellen erlaubt.The particular advantage of the method is that it is possible in this way to produce a tension member for a rock bolt in a continuous process, which can be cut to any length and, if the profile is formed on its outer surface as a screw thread, also screwing one Anchoring body allowed at any point.

Die Erfindung wird nachstehend anhand der Zeichnung näher erläutert. Es zeigt

  • Fig.1 einen Längsschnitt durch einen Felsbolzen mit einem erfindungsgemäß ausgebildeten Zugglied,
  • Fig. 2 eine Draufsicht auf die luftseitige Verankerung des Felsbolzens entlang der Linie II-11 in Fig. 1,
  • Fig. 3 einen Querschnitt entlang der Linie 111-111 in Fig. 1,
  • Fig. 4 einen Ausschnitt aus dem Felsbolzen gemäß Fig. 1 nach einer Verbiegung infolge einer kombinierten Schere und Biegebeanspruchung, die
  • Fig.5 bis 7 aufeinanderfolgende Phasen der Herstellung des Zuggliedes und
  • Fig. 8 einen Längsschnitt durch einen Felsbolzen mit einer anderen Ausführungsform des Zugglieds.
  • Fig. 1 zeigt im Längsschnitt, Fig. 2 in Draufsicht und Fig. 3 im Querschnitt einen Felsbolzen mit einem Zugglied nach der Erfindung. Das Zugglied 1 besteht bei diesem Ausführungsbeispiel aus insgesamt acht Stahldrähten 2, die in einen rohrförmigen Körper 3 aus einer erhärtenden Masse, z. B. aus einem Kunstharz, vorzugsweise Polyesterharz, eingebettet sind. Im Inneren des rohrförmigen Körpers 3 befindet sich ein zentraler Holraum 4; seine Außenfläche weist eine Profilierung 5, z. B. in Form eines groben Gewides auf, das zum Aufschrauben eines Verankerungskörpers, z. B. Mutter, geeignet ist.
  • Das Zugglied 1 ist in ein Bohrloch 6 eingesetzt, das selbstverständlich in beliebiger Richtung zu dem zu sichernden unterirdischen Hohlraum geneigt sein kann und am Grunde des Bohrloches durch ein erhärtendes Material 7, z. B. ein Kunstharz oder Zementmörtel, festgelegt. Dieses erhärtende Material kann, wie bei sogenannten Kunstharzklebeankern üblich, in Form einer zwei Kleberkomponenten enthaltenden Patrone in das Bohrloch 6 eingebracht werden, die beim Einführen des Zugglieds zerstört wird, wodurch der Kleber aktiviert wird. Das erhärtende Material kann aber auch entweder durch den zentralen Hohlraum 4 oder unmittelbar in den äußeren Ringraum injiziert werden; im letzteren Fall kann der zentrale Hohlraum 4 als Entlüftungsleitung dienen.
  • An der Bohrlochmündung ist das Zugglied 1 durch einen Verankerungskörper 8 mit einem versenkten Schraubteil 9' festgelegt, das sich mittels eines umgebördelten Randes 9" gegen eine Widerlagerplatte 10 mit einer zentralen Durchbrechung 11 abstützt. Die Widerlagerplatte 10 ist im Bereich der Durchbrechung 11 aufgebogen, wodurch ein Kraftschluß in Form einer federnden Verspannung erreicht wird. Diese versenkte Anordnung des Schraubteils 9' des Verankerungskörpers 8 hat den Vorteil, daß das Schraubteil 9', das bei der gegenüber Stahl geringeren Festigkeit des rohrförmigen Körpers 3 eine große Länge haben muß, nicht um diese Länge über die Oberfläche des unterirdischen Hohlraums nach innen in diesen hineinragt.
  • In Fig. 4 ist angegeben, wie sich das Zugglied 1 bei einer infolge einer gegenseitigen Verschiebung von Felspaketen auftretenden lokalen Scherbeanspruchung verformen kann. Die Verformung ist hier in dem Bereich des Felsbolzens angenommen, in dem das Zugglied keinen Verbund zum Gebirge besitzt. Dabei ist unterstellt, daß sich einer der Stahldrähte 4 aus seiner Einbettung in dem rohrförmigen Körper 3 gelöst hat und in den zentralen Hohlraum 4 hinein ausgewichen ist; dies ist für den Draht 2' im Querschnitt der Fig. 3 gestrichelt angedeutet.
  • Das Zugglied nach der Erfindung, das Längen von 4 bis 6 m, gegebenenfalls auch bis 8 m aufweisen kann, besteht beispielsweise bei einem Außendurchmesser von ca. 25 mm aus Stahldrähten mit 6 mm Durchmesser; der zentrale Hohlraum 4 hat dann einen Durchmesser von 9 mm. Das Zugglied kann beispielsweise durch Extrudieren hergestellt werden, wobei die Drähte dem Extrudierkopf seitlich zugeführt werden müssen, um sie vollständig einhüllen zu können.
  • Eine besonders vorteilhafte Möglichkeit zur Herstellung eines Zuggliedes nach der Erfindung ist in den Fig. 5 bis 7 in einzelnen Phasen dargestellt. Dabei wird in einem kontinuierlichen Verfahren zunächst ein Innenrohr 3' aus einem thermoplastischen Material, z. B. PVC, durch Extrudieren hergestellt, das den zentralen Hohlraum 4 bildet (Fig. 5). Noch bevor das Material des Innenrohrs 3' vollständig erhärtet ist, werden in radialer Richtung von außen die Drähte 2 zugeführt und in regelmäßiger Folge entlang des Außenumfanges des Innenrohrs 3' in dessen Umfangsfläche eingedrückt (Fig. 6).
  • In einem weiteren Verfahrensschritt werden die Drähte 2 durch die erhärtende Masse 3", z. B. ein reagierendes Kunstharz, wie ein Polyesterharz oder dergleichen, eingehüllt. Auf dieses kann schließlich noch ein äußeres Hüllrohr 12 aus einem thermoplastischen Kunstoff, z. B. PVC, aufextrudiert werden. Bei dieser Ausführungsform weist dieses äußere Hüllrohr 12 das grobe Gewinde auf, das zum Aufschrauben der Verankerungsmutter dient.
  • Eine weitere Ausführungsform der Erfindung ist in Fig. 8 dargestellt. Das Zugglied 1', das hier analog wie in Fig. 1 als Felsbolzen dient, ist nicht über seine gesamte Länge mit einem Gewinde versehen, sondern nur über Teilbereiche 13, die jeweils von Bereichen 14 mit glatter Oberfläche unterbrochen sind. Bei diesem Zugglied bilden die mit Gewinden versehenen Bereiche 13 Verankerungen gegenüber dem das, Bohrloch 6 in voller Länge ausfüllenden erhärtenden Material 7. Die glatten Bereiche 14 gehen keinen Verbund mit dem erhärtenden Material 8 ein, so daß das Zugglied 1' sich in den Bereichen 14 zwischen den Zwischenverankerungen 13 stärker dehnen kann.
  • Der rohrförmige Körper 3, in den die Drähte 2 eingebettet sind, kann in den Bereichen zwischen den Stahldrähten 2 noch mit radialen Durchbrechungen versehen sein. Diese Durchbrechungen, die auch nur in Teilbereichen über die Länge des Zugglieds angeordnet sein können, dienen als Injizier- und/oder Entlüftungsöffnungen. Das Injizieren des nach dem Einsetzen des Zuggliedes in das Bohrloch verbliebenen Ringraumes mit einem erhärtenden Material, z. B. Zementmörtel, kann durch den zentralen Hohlraum und die Durchbrechungen hindurch erfolgen. Um den zentralen Hohlraum nachträglich wieder frei zu machen, kann das darin verbliebene Injektionsmaterial herausgespült werden.
  • Die Durchbrechungen können aber auch ventilartig ausgebildet sein, etwa in der Weise, daß sie bei einem Injizieren des Ringraumes durch eine in diesem angeordnete gesonderte Injizierleitung als Entlüftungsöffnungen dienen, d. h. vom äußeren Ringraum zum zentralen Hohlraum hin nur die eingeschlossene Luft entweichen lassen, nicht aber das Injiziermaterial oder etwa hieraus abgesondertes Wasser.
The invention is explained below with reference to the drawing. It shows
  • 1 shows a longitudinal section through a rock bolt with an inventive tension member,
  • 2 is a plan view of the air-side anchorage of the rock bolt along the line II-11 in Fig. 1,
  • 3 shows a cross section along the line 111-111 in FIG. 1,
  • Fig. 4 shows a section of the rock bolt according to FIG. 1 after bending due to a combined pair of scissors and bending stress
  • 5 to 7 successive phases of the manufacture of the tension member and
  • Fig. 8 shows a longitudinal section through a rock bolt with another embodiment of the tension member.
  • Fig. 1 shows in longitudinal section, Fig. 2 in plan view and Fig. 3 in cross section a rock bolt with a tension member according to the invention. The tension member 1 consists in this embodiment of a total of eight steel wires 2, which in a tubular body 3 made of a hardening mass, for. B. are embedded from a synthetic resin, preferably polyester resin. In the interior of the tubular body 3 there is a central cavity 4; its outer surface has a profile 5, z. B. in the form of a coarse thread, which for screwing on an anchoring body, for. B. mother is suitable.
  • The tension member 1 is inserted into a borehole 6, which can of course be inclined in any direction to the underground cavity to be secured and at the bottom of the borehole by a hardening material 7, for. B. a synthetic resin or cement mortar. This hardening material can, as is customary in the case of so-called synthetic resin adhesive anchors, be introduced into the borehole 6 in the form of a cartridge containing two adhesive components, which is destroyed when the tension member is inserted, thereby activating the adhesive. The hardening material can also be injected either through the central cavity 4 or directly into the outer annular space; in the latter case, the central cavity 4 can serve as a vent line.
  • At the mouth of the borehole, the tension member 1 is fixed by an anchoring body 8 with a countersunk screw part 9 ′, which is supported by means of a flanged edge 9 ″ against an abutment plate 10 with a central opening 11. The abutment plate 10 is bent open in the area of the opening 11, so that This recessed arrangement of the screw part 9 'of the anchoring body 8 has the advantage that the screw part 9', which must have a great length given the lower strength of the tubular body 3 compared to steel, does not extend around it Length inwardly protrudes into the surface of the underground cavity.
  • 4 shows how the tension member 1 can deform when a local shear stress occurs as a result of mutual displacement of rock packs. The deformation is assumed here in the area of the rock bolt, in which the tension member has no connection to the mountains. It is assumed that one of the steel wires 4 has come loose from its embedding in the tubular body 3 and has evaded into the central cavity 4; this is indicated by dashed lines for the wire 2 'in the cross section of FIG. 3.
  • The tension member according to the invention, which can have lengths of 4 to 6 m, optionally also up to 8 m, consists, for example, of an outer diameter of approx. 25 mm from steel wires with a diameter of 6 mm; the central cavity 4 then has a diameter of 9 mm. The tension member can be produced, for example, by extrusion, the wires having to be fed laterally to the extrusion head in order to be able to completely encase them.
  • A particularly advantageous possibility for producing a tension member according to the invention is shown in individual phases in FIGS. 5 to 7. In a continuous process, an inner tube 3 'made of a thermoplastic material, e.g. B. PVC, produced by extrusion, which forms the central cavity 4 (Fig. 5). Even before the material of the inner tube 3 'has completely hardened, the wires 2 are fed in from the outside in the radial direction and are pressed into the circumferential surface of the inner tube 3' in a regular sequence along the outer circumference (FIG. 6).
  • In a further process step, the wires 2 are enveloped by the hardening mass 3 ″, for example a reactive synthetic resin, such as a polyester resin or the like. Finally, an outer sheath tube 12 made of a thermoplastic material, for example PVC, can be attached to this In this embodiment, this outer cladding tube 12 has the coarse thread that serves to screw on the anchoring nut.
  • Another embodiment of the invention is shown in FIG. 8. The tension member 1 ', which here serves as a rock bolt analogously to FIG. 1, is not provided with a thread over its entire length, but only over partial areas 13, which are each interrupted by areas 14 with a smooth surface. In this tension member, the threaded areas 13 form anchorages with respect to the hardening material 7 that fills the full length of the borehole 6. The smooth areas 14 do not form a bond with the hardening material 8, so that the tension member 1 'is in the areas 14 can stretch more between the intermediate anchors 13.
  • The tubular body 3, in which the wires 2 are embedded, can also be provided with radial openings in the areas between the steel wires 2. These openings, which can also be arranged only in partial areas over the length of the tension member, serve as injection and / or ventilation openings. Injecting the annular space remaining after insertion of the tension member into the borehole with a hardening material, e.g. B. cement mortar, can be done through the central cavity and the openings. In order to subsequently clear the central cavity, the injection material remaining in it can be rinsed out.
  • The openings can also be designed like a valve, for example, in such a way that they serve as ventilation openings when the annular space is injected through a separate injection line arranged therein, that is to say only the trapped air can escape from the outer annular space to the central cavity, but not that Injection material or water separated therefrom.

Claims (12)

1. A tension member for a rock bolt or the like, comprising a bundle of steel wires (2), characterised in that the steel wires are embedded in a tubular body (3) consisting of plastic material, for example synthetic resin, which hardens while leaving a central cavity (4), and in that the outer surface of the tubular body (3) is of corrugated profile (5).
2. A tension member according to claim 1, characterised in that the steel wires (2) are disposed radially symmetrically in cross-section.
3. A tension member according to claim 1 or 2, characterised in that the tubular body (3) is of circular cross-section.
4. A tension member according to any one of claims 1 to 3, characterised in that the central cavity (4) is of circular cross-section.
5. A tension member according to any one of claims 1 to 3, characterised in that the corrugated profile (5) is in the form of a screw thread.
6. A tension member according to claim 5, characterised in that the corrugated profile (5) extends only over portions (13) of the length of the tension member (1'), and in that portions (14) with a smooth outer surface are provided between the portions (13) provided with a corrugated profile.
7. A tension member acording to any one of claims 1 to 6, characterised in that the tubular body (3) is surrounded by a sheath (12) on which the corrugated profile (5) is formed.
8. A tension member according to claim 7, characterised in that the sheath (12) consists of a thermoplastic synthetic resin, for example PVC.
9. A tension member according to any one of claims 1 to 8, characterised in that outwardly directed openings are provided at least in portions of the length of the tension member along at least one generator of the central cavity.
10. A tension member according to claim 9, characterised in that the openings are of valve- like form.
11. A method of producing a tension member according to claims 1 to 10, characterised in that in a continuous process firstly an inner tube (3') forming the central cavity (4) is produced from thermoplastic synthetic resin, for example PE, in that prior to the hardening of the material of the inner tube (3') the steel wires (2) are introduced along its outer surface and are pressed into its surfacend in that the steel wires (2) are then enveloped by a plastic compound (3") which hardens, for example a polyester resin.
12. A method according to claim 11, characterised in that finally the sheath (12) is applied consisting, for example, of a thermoplastic synthetic resin such as PVC.
EP86102426A 1985-03-05 1986-02-25 Tension element for a rock bolt or the like Expired EP0196451B1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT86102426T ATE36893T1 (en) 1985-03-05 1986-02-25 TENSION FOR A ROCK PIN OR LIKE.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE3507732 1985-03-05
DE19853507732 DE3507732A1 (en) 1985-03-05 1985-03-05 TIE LINK FOR A ROCK BOLT OR THE LIKE

Publications (2)

Publication Number Publication Date
EP0196451A1 EP0196451A1 (en) 1986-10-08
EP0196451B1 true EP0196451B1 (en) 1988-08-31

Family

ID=6264238

Family Applications (1)

Application Number Title Priority Date Filing Date
EP86102426A Expired EP0196451B1 (en) 1985-03-05 1986-02-25 Tension element for a rock bolt or the like

Country Status (9)

Country Link
US (1) US4664555A (en)
EP (1) EP0196451B1 (en)
JP (1) JPS61207800A (en)
AT (1) ATE36893T1 (en)
AU (1) AU565512B2 (en)
CA (1) CA1270129A (en)
DE (1) DE3507732A1 (en)
NO (1) NO860728L (en)
ZA (1) ZA861450B (en)

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Also Published As

Publication number Publication date
JPS61207800A (en) 1986-09-16
DE3507732C2 (en) 1987-12-10
NO860728L (en) 1986-09-08
AU565512B2 (en) 1987-09-17
DE3507732A1 (en) 1986-09-18
AU5424986A (en) 1986-09-11
US4664555A (en) 1987-05-12
ZA861450B (en) 1986-10-29
CA1270129A (en) 1990-06-12
ATE36893T1 (en) 1988-09-15
JPH0519640B2 (en) 1993-03-17
EP0196451A1 (en) 1986-10-08

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