EP0739442A1

EP0739442A1 - Tensionable gfp rock anchor

Info

Publication number: EP0739442A1
Application number: EP95905526A
Authority: EP
Inventors: Wolfgang Habe; Wilhelm Schauerte; Jochen Kasselmann; Luigi Giamundo
Original assignee: ATP Srl AVANZATE TECNICHE DI PULTRUSIONE; F Willich Berg- und Bautechnik & Co GmbH; WILLICH F BERG BAUTECHNIK; ATP Srl AVANZATE TECNICHE DI
Current assignee: ATP Srl AVANZATE TECNICHE DI PULTRUSIONE; Fosroc International Ltd
Priority date: 1994-01-12
Filing date: 1995-01-10
Publication date: 1996-10-30
Anticipated expiration: 2015-01-10
Also published as: JPH09507543A; EP0739442B1; DK0739442T3; ATE156892T1; GR3025361T3; JP3424190B2; DE59500513D1; KR100229706B1; ES2109809T3; DE19517257A1; DE4400644A1; WO1995019491A1

Abstract

A rock anchor (1), which can be secured in any position by fitting a tensioner, has a securing section (4) consisting of a tensioning sleeve (6) with a counter taper (7) and a wedge (8) matching the tensioning sleeve (6) which can be fitted over the anchor pin (2). The wedge slope is about 3 DEG , as is that of the taper (7), so that it is possible not only to insert the wedge (8) reliably into the taper (7) but also to apply the tensional forces evenly without peak tensions and consequent wear on the GFP anchor pin. The GFP anchor pin does not have to be slotted; rather, securing is effected by suitably fitting the securing section (4) and fixing the wedge (8) by a tensioner (9) or a tensioning screw (16), so that the fixing may be made at virtually any point on the anchor pin (2).

Description

Tensionable GfK mountain anchor

Description

The invention relates to a rock bolt with the GRP anchor rod, the tension element which can be braced deepest in the borehole, and the clamping element on the borehole mouth side, which consists of a calotte plate and a fixing part abutting the anchor rod.

Mountain anchors are used in rock construction as well as in underground mining where the mountains themselves have sufficient stability, but where the layers close to the cavity produced are to be secured by tacking them together. Rock anchors made of steel are known, as are those made of GRP material. EP-A 94 908 discloses a glass-fiber reinforced plastic anchor, which material is not only characterized by its very high tensile strength but also by its low weight. The anchor rod as such cannot corrode, so that it also has a long service life. For bracing, the GRP pipe is provided with a thread on which the anchor screw is moved. A GRP anchor is known from EP-A 188 174, in which a corresponding thread is applied to the end protruding from the borehole. The anchor nut with spherical washer can be moved on this thread, so that the anchor can be braced. It is disadvantageous, however, that a large production outlay is required for the thread and that special importance must be attached to the formation of the thread in order to ensure the necessary power transmission. It has been shown that the thread, which is preferably glued onto the GRP pipe, does not withstand high loads, but rather tears off. In order to prevent this tearing off, according to DE-OS 29 03 694 a slitting of the GfK- The end of the tube and the insertion of a corresponding wedge are provided so that it can be braced without fear of tearing off the thread. However, the prerequisite is that appropriate wedges are attached to both ends, since otherwise it is not possible to secure them with sufficient security. Another disadvantage is that resinification of the borehole is theoretically possible, but can only be achieved with considerable effort. Finally, it is disadvantageous that an approximately right-angled arrangement between the anchor rod and the rock face is required in order to enable the calotte washer to be properly clamped over the anchor nut. In addition, a multi-wedge arrangement is provided which not only requires a complex manufacturing process, but also difficult assembly. The wedge or the wedges attached to both ends have a large slope to prevent them from being pressed out of the GRP pipe during the tensioning process. A similar solution is known from EP-A 14 426, in which the fixing of the anchor is achieved in that an expansion sleeve which grips in the borehole is placed on the end of the tension element arranged in the borehole. At the opposite end, a tension nut is provided which can be clamped to the outer end of the tension element when rotating via tension means. The spreading apart of the slotted end of the GRP pipe is achieved in that the expansion sleeve has a corresponding inner bore, which, according to a special embodiment, even runs conically in the upper region, so as to enable the expansion mandrel to be driven completely into the expansion sleeve. The disadvantage here is that in the transition area, ie where the wall of the GRP pipe is pressed against the inner wall of the expansion sleeve, stress peaks form which can lead to tearing, so that the effectiveness of the anchor is then excluded is. The distribution of the forces given by the shape of the expanding mandrel on the one hand and the expanding sleeve on the other is unfavorable and, moreover, cannot be determined exactly, so that precise work with such a GRP anchor leadership is not possible. From DE-PS 39 02 727 finally a GRP rock anchor is known, in which the expanding mandrel and the inner wall of the conical sleeve are correspondingly conical, so that stress peaks cannot occur in this area. In this as well as in the other described solutions, an expansion wedge must be introduced, which requires a cross-shaped splitting of the GRP anchor rod. Thus, the tensioning element can only be attached to the given ends of the anchor rod, and in particular it is not possible to ensure the effectiveness of the rock anchor even after the application of shotcrete by retightening or the like.

The invention is therefore based on the object of providing a fixing part which can be attached simply and securely to the end of the borehole mouth and which at the same time can also absorb high tensile loads and which is to be fixed more or less at every point of the anchor rod.

The object is achieved in that the fixing part of a clamping sleeve with a counter cone and a correspondingly designed wedge that can be pushed onto the anchor rod and which is displaceable in the longitudinal direction of the clamping device via a clamping device that can be displaced on the anchor rod and partially inserted into the clamping sleeve or the counter cone Counter cone is displaceable, is formed and that the wedge on the inner surface has a larger coefficient of friction than on the outer surface.

In the case of such a rock anchor, the disadvantageous splitting of the GRP pipe or the GRP anchor rod, which precisely defines the fixing location, can be dispensed with entirely. Rather, the clamping sleeve with the counter cone is pushed onto the anchor rod, whereupon the wedge is then also pushed onto the anchor rod and pushed into the clamping sleeve with counter cone. This insertion of the wedge into the adapter sleeve and counter cone is supported or acts through a tensioning device that pulls into the tensioning sleeve or the counter cone and pushes the wedge in front of it. Since the wedge has a greater coefficient of friction on the inner surface than on the outer surface, it can accordingly be inserted into the clamping sleeve or the counter cone. At the same time, it fixes itself and thus the entire fixing part in the correspondingly provided area on the GRP anchor rod, so that an effective and permanent connection is created without stress peaks occurring in any area. Rather, the tensile forces are applied uniformly over the entire length of the clamping sleeve to the GRP anchor rod, so that there is no fear of tearing off. If a post-tensioning is then to be carried out, for example because shotcrete is applied afterwards, after the shotcrete has hardened the previously removed clamping sleeve with counter cone can be re-applied and fixed as described. This creates a very versatile solution which is adapted to the operational circumstances and which is distinguished by long service lives and, as mentioned, the absorption of high tensile forces. It is particularly advantageous that the GRP anchor rod can be cut to any desired length in order to complete the rock anchor by applying the tensioning element or fixing part. Due to the special design of the wedge used, slipping is prevented because, as mentioned, the inner surface has a greater coefficient of friction than the outer surface.

According to an expedient embodiment of the invention, it is provided that the fixing part is made of fiber composite material, the clamping sleeve consisting of radially wound plastic material. This fiber composite material has a significantly more favorable property than the previously used fiber-reinforced plastic, so that the term GRP anchor rod or GRP rock anchor is no longer applicable per se. The fixing part can be adjusted to the expected tensile Stungen can be adapted advantageously, tensile forces of well over 10 t can ultimately be applied, for example, by using aluminum for the wedge. In addition, the material of the adapter sleeve is important, fiber composite material being applied according to the invention. The adapter sleeve consists of a radial radial fiber-reinforced plastic. This material, but in particular also that of the wedge, can be designed such that the glass fibers used in each case are arranged approximately perpendicular to the anchor rod. The appropriately designed adapter sleeve in particular allows more than 16 t tensile load.

In order to facilitate the arrangement of the wedge, it is provided according to the invention that the wedge of the fixing part is designed in two parts and in this way to represent two half-shells. These two half-shells are placed around the anchor rod and then pushed along it into the clamping sleeve or the counter cone until there is a lock due to the slope of the wedge. This is then overcome as far as possible and necessary via the tensioning device and provides the certainty that the two-part wedge assumes the necessary and correct end position.

The counter cone and the wedge are aligned with each other with regard to their shape, but also with regard to the material used. In order to enable a respective coordination here, the invention provides that the counter cone is molded onto the adapter sleeve and has a different material mixture. While the clamping sleeve as such must absorb high compressive forces, the material and the shape of the counter-cone should ensure that the wedge can also be pushed or pressed far enough in order to then apply correspondingly high frictional forces and thus enable fixing. It is also conceivable that the wedge consists of several partial wedges to be arranged one behind the other in the longitudinal direction of the clamping sleeve, which, depending on the length, mender tensile forces u. Ä. May be appropriate.

As already mentioned, the effectiveness of the clamping element on the mouth of the borehole can be achieved by adapting the wedge and counter wedge, and of course also by means of the respective slope. It has been found to be optimal that the wedge has a wedge slope of 1 - 7.5 °, preferably 3 - 4 °. This and the specific choice of material prevent the wedge from pulling through and ensure a secure fit in the counter cone and thus in the adapter sleeve.

If, for certain reasons, the choice of material is to be changed, this is possible without great effort, also with regard to the material used, by appropriately selecting the corresponding wedge or by specifying the material. This is particularly favorable if the wedge has 25-35% of the total amount of material of the wedge and counter cone.

It was pointed out earlier that in any case the wedge should have a higher coefficient of friction on the inner surface than on the outer surface, which can be achieved according to an expedient embodiment of the invention in that the friction surface between the anchor rod and the inner surface of the wedge is enlarged by an adapted shape. For example, it is conceivable to effectively enlarge the surface of the anchor rod by means of corresponding arcuate recesses or the like.

According to an appropriate design, it is also possible, however, to roughen the inner surface of the wedge or to assign a similar surface design to it in order to specifically change, ie to increase, the coefficient of friction in this way. As a rule, the surface of the wedge is changed and not that of the counter cone; this alone because the corresponding inner surface of the Keils and that of the anchor rod lie against each other.

The rock anchor according to the invention can also be used as an adhesive anchor or can be used for pressing work if, as provided according to the invention, the anchor rod has an inner bore. The same is achieved during the manufacturing process when the long glass fibers are placed against one another and shaped, which are then embedded in the appropriate material and dictate the dense wall of the anchor tube. Solidification material is pressed into the deepest hole of the borehole via the inner bore, so that the anchor can be glued over its entire length, with simultaneous gluing of the adjacent rock layers.

If it is desired to ensure that synthetic resin or other hardening material can emerge at several points along the length of the anchor rod, it is advantageous if the inner bore is oval and / or has sections that extend to the outer surface. This particular embodiment then leads to the bulges in the predetermined regions allowing the adhesive material to pass through, so that the desired effect occurs. The disadvantage here is that the tensile strength of the anchor rod may suffer, in particular if these bulges are provided more or less regularly over the length.

If tensioning of the rock bolt is necessary, this can be achieved with the help of a further development of the invention by the tensioning sleeve being designed to be displaceable in the longitudinal direction of the anchor rod relative to the cathode plate. A sufficiently high pretension can thus be applied so that the effectiveness of the rock bolt is increased in a targeted manner. This is made possible in particular by the fact that the clamping sleeve has an external thread at the end facing the cap plate, the cap plate having a corresponding thread formation. In order to further simplify the clamping element, the invention provides that the clamping sleeve or the counter-cone is pivotally mounted in the spherical cap only in one direction. The spherical design of the clamping sleeve can thus be completely dispensed with, which enables simpler production and which nevertheless allows the clamping element to be fixed practically at any point on the anchor rod. Since variations in the wide range are possible due to the design of the anchor rod and also of the tensioning element, the tensioning sleeve and the calotte plate can also be mounted at the same time, which is also facilitated in particular by the fact that the calotte plate is used for transportation with the cone and thus with the tensioning sleeve Shear pins are connected. If the assembly is now carried out and a first movement against one another, these shear pins are sheared off and the counter cone or the clamping sleeve can pivot and move as desired with respect to the spherical plate.

The wedge is driven into the counter cone by means of a clamping device. It is particularly expedient here if the tensioning device is designed as a tensioning screw which can be displaced on the anchor rod and which has an external thread corresponding to an internal thread assigned to the tensioning sleeve. This training, d. H. that is, the tensioning screw, which can be screwed into the tensioning sleeve on the anchor rod, enables the wedge to be inserted evenly and effectively in such a way that the tensioning element or fixing part is effectively fixed on the anchor rod.

The invention is characterized in particular by the fact that a rock anchor is created which can be fixed effectively and absorbing high tensile forces at the end of the borehole mouth, this being done with relatively simple means and being so simple that even inexperienced people are concerned with it can be. The fixing part is delivered as a complete unit and then onto the part from the borehole mouth. protruding anchor rod pushed on, whereupon ultimately only the wedge must be tightened via the clamping screw in order to achieve an effective connection between the fixing part or clamping element and anchor rod. The clamping screw has a thread which corresponds to a thread in the counter cone, so that a uniform retraction or a uniform displacement of the wedge is ensured. The special design of the wedge and counter cone ensures uniform force transmission and thus a permanent and secure connection between the anchor rod and the fixing part described. By appropriate choice of material, tensile forces of 13 t and more can be applied, so that an adaptation to the respective circumstances is also possible without having to change to another type of anchor. The fixing part can advantageously be attached practically at any point on the anchor rod, so that readjustment or re-tensioning can also be achieved without any problems, especially since the bracing can be achieved by appropriate design of the fixing part.

Further details and advantages of the subject matter of the invention result from the following description of the accompanying drawing, in which a preferred exemplary embodiment is shown with the details and individual parts necessary for this. Show it:

1 shows a rock anchor at the borehole mouth end in section,

2 the counter cone in section,

3 the clamping device or clamping screw in section,

4 is a perspective view of the wedge,

Fig. 5 shows a cross section through the anchor rod and

6 shows a perspective illustration of the cathode plate. Fig. 1 shows a rock anchor 1 in side view, with the end protruding from the borehole mouth. It is clear in the section shown here that the anchor rod 2, here consisting of a GRP pipe, is effectively connected between the calotte plate 3 and the end region with a fixing part 4, shown here in section.

This fixing part 4 consists of the clamping sleeve 6 and the counter-cone 7 and the wedge 8. The clamping sleeve 6 consists of a radially wound GRP material, which clamping sleeve can hold 17-18 t.

The counter cone 7 is injection molded onto the clamping sleeve 6 and consists of a material which corresponds to the material of the wedge 8.

The wedge 8 on the anchor rod 2 is pushed into the counter cone 7 via the tensioning device 9, so that the uniform and effective forces act on the anchor rod 2 without leading to problem zones and thus tearing.

The coefficient of friction of the inner surface 10 is greater than the coefficient of friction of the outer surface 11, so that an effective "adhesion" of the wedge 8 on the anchor rod 2 is ensured. The wedge 8 has an incline of 3-4.5 °, the optimum being 3 °. A slope of the wedge 8 can be prevented in any case by means of the slope and choice of material, and an effective fixing of the fixing part 4 on the anchor rod 2 can be ensured.

The inner wall 12 of the counter cone 7 and the outer surface 11 of the wedge 8 have a corresponding slope, so that the uniform application of the forces is ensured. A further secure absorption of the forces is ensured via the collar ring 13, the end of the clamping sleeve 6 facing the cathode plate 3. The end of the counter cone 7 is provided with an extension 14, so that when the counter cone 7 is injected into the clamping sleeve 6, an intensive connection is obtained despite the different choice of materials.

At the end of the mating cone 7 opposite the collar ring 13, the latter has an internal thread 15 which is designed to correspond to the external thread 17 of the clamping screw 16 serving as a clamping device 9. This clamping screw 16, which expediently has a hexagon 18 or the like, can be screwed securely into the counter cone 7, in order to simultaneously press the wedge 8 into the counter cone 7.

2 shows a section through the counter-cone 7, the collar ring 13 becoming clear at the end 31 facing the spherical cap plate 3 and the extension 14 at the opposite end with the internal thread 15. The clamping sleeve 6, not shown here, is made of radially wound GRP material is virtually embedded in this counter cone 7 or, more correctly, the counter cone 6 is injection molded into the clamping sleeve or onto the clamping sleeve 6.

Fig. 3 shows the clamping screw 16 with the external thread 17 and the hexagon 18, it being clear that this clamping screw 16 is characterized by a simple structure.

The wedge 8, which is important for the effectiveness of the rock bolt 1, is shown in a perspective view in FIG. 4. The outer surface 11 is characterized by the gradient of 3 - 4.5 ° already mentioned. 4 that the inner surface 10 of the wedge 8 consisting of two half-shells 20, 21 has been given an enlarged friction surface 22 by a special shape 23. This shape 23 coincides with the shape of the anchor rod 2 shown in FIG. 5, so that the much higher friction surfaces 22, 22 ′ sought here are achieved. give .

5 shows, as mentioned, a section through an anchor rod 2, the outer surface 26 being characterized by the shape 23 already mentioned with the enlarged friction surface 22 '. An inner bore 26 is provided in the center, this inner bore being able to have an oval shape if lateral exits are desired in certain areas. Then it is expedient to provide the inner bore 26 with lateral bulges 27, 28, so that, as already mentioned, the compression material pressed up by the inner bore 26 can emerge laterally from the anchor rod 2 in certain areas.

6 finally shows a perspective representation of the spherical cap 3, specifically from the side facing the clamping sleeve 6 and the counter cone 7. Here it becomes clear that the dome plate 3 equipped with the bore 32 specifies a sliding surface 30 which only allows the clamping sleeve 6 or the counter cone 7 to move in one direction. The counter cone 7 and the clamping sleeve 6 are not spherical, so that taking into account the special design of the calotte plate 3, the described limited mobility is achieved.

All of the features mentioned, including those that can be seen in the drawings alone, are considered to be essential to the invention, alone and in combination.

Claims

Patent claims

1. Mountain anchor with the GRP anchor rod, the tension element deepest in the borehole and the tension element consisting of calotte plate and a fixation part resting on the anchor rod nut (7) and a correspondingly designed wedge (8) which can be pushed onto the anchor rod (2) and which is displaceable in the longitudinal direction of the counter cone via a tensioning device (9) which can be displaced on the anchor rod (2) and is partially insertable into the clamping sleeve or the counter cone , is formed and that the wedge (8) on the inner surface (10) has a greater coefficient of friction than on the outer surface (11).

2. Rock anchor according to claim 1, that the fixing part (4) is made of fiber composite material, the clamping sleeve (6) consisting of radially coiled plastic material.

3. Rock anchor according to claim 1 and claim 2, d a d u r c h g e k e n n z e i c h n e that the wedge (8) of the fixing part (4) is formed in two parts and two half-shells (20, 21) representing.

4. rock anchor according to claim 1, d a d u r c h g e k e n n e e c h n e t that the counter cone (7) is injection molded onto the clamping sleeve (6) and has a different material mixture.

5. rock anchor according to claim 1, characterized in that the wedge (8) from several in the longitudinal direction of the clamping sleeve se (6) to be arranged in part wedges.

6. rock anchor according to claim 1 to claim 5, characterized in that the wedge (8) has a wedge slope of 1-7.5 ^° , preferably 3-4 °.

7. rock anchor according to claim 1 to claim 6, d a d u r c h g e k e n n z e i c h n e that the wedge (8) has 25 - 35% of the total amount of material of the wedge (8) and counter cone (7).

8. rock anchor according to claim 1, d a d u r c h g e k e n n z e i c h n e that the friction surface (22) between the anchor rod (2) and inner surface (10) of the wedge (8) is increased by adapted shape (23).

9. rock anchor according to claim 1, d a d u r c h g e k e n n z e i c h n e that the inner surface (10) of the wedge (8) is roughened or has a similar surface design.

10. rock anchor according to claim 1, d a d u r c h g e k e n n z e i.c h n e t that the anchor rod (2) has an inner bore (26).

11. Rock anchor according to claim 10, so that the inner bore (26) is oval and / or has sections (27, 28) extending to the outer surface (25).

12. rock anchor according to claim 1, characterized in that the clamping sleeve (6) relative to the calotte plate (3) in Longitudinal direction of the anchor rod (2) is designed to be displaceable.

13. rock anchor according to claim 12, so that the clamping sleeve (6) has an external thread at the end (31) facing the calotte plate (3).

14. Rock anchor according to claim 1, so that the clamping sleeve (6) or the counter-cone (7) is pivotally mounted in the calotte plate only in one direction.

15. rock anchor according to claim 1 and claim 14, d a d u r c h g e k e n n z e i c h n e that the calotte plate (3) for transport with the Gegen¬ cone (7) and thus with the clamping sleeve (6) is connected via shear pins.

16. Rock anchor according to claim 1 to claim 15, characterized in that the tensioning device (9) is designed as a displaceable on the anchor rod (2) tensioning screw (16) which has an associated with one of the clamping sleeve (6) internal thread (15) corresponding external thread ( 17).