Anchoring device for supporting excavations in rock

Abstract

 Anchoring device (10) for supporting excavations in rock constituted by a hollow screw-threaded tube (11) with which a nut (13) and a plate (14) are associated, and a section bar (12) provided with teeth (17) which are suitable for entering a plurality of openings (16) provided on the surface of the same tube; the section bar (12) is free to perform movements which shift it towards said tube, and, inversely, away from it, when the nut (13) with the plate (14) is respectively tightened (screwed down) or released (unscrewed).

Description

[0001] The present invention relates to an anchoring device for supporting excavations in rock.

[0002] Anchorings of the so-said "mechanical-expansion" type, also said "stays", i.e., end-acting anchoring means, are known, which are generally constituted by a metal rod provided with screw-threadings at both of its ends. Onto one of the two ends of the rod an expansion head is fastened, which locks the anchoring in its preset seat, and at the other end of said rod a nut is screwed down or anyway fastened, which nut, by coming to rest against the rock by means of a plate and consequently applying a pressure onto said rock, puts said rod under tension, theoretically sewing to one another the strata which are between the head and the retainer nut. Such a type of anchoring, which is very useful as an "instant" anchoring, loses its effectiveness over time.

[0003] Another type of anchoring is provided on the contrary with devices which are substantially analogous to those as hereinabove disclosed, but in which injections of fluid packing material or of resins are used. By means of these anchoring types good results can be achieved, but in longer times; furthermore, without said injection of packing materials the anchoring does not perform its task.

[0004] Still another type of anchoring consists of a steel tube with a section bent into an "omega"-shape, into the interior of which high-pressure water is pumped, the effect of which is of causing the tube to expand, bringing it into contact with the wall of the bore inside which the tube is inserted. Also in this case good results are obtained; the drawback consists in that in order to cause the tube to expand, an intervention with further operations and special equipment has to be carried out.

[0005] The main purpose of the instant invention is of providing an anchoring device for excavations in rock, which is capale of allowing the support to be immediately achieved throughout the length of the same anchoring, and without any further equipment having to be used in order to secure the safety of those who are working inside the interior of the excavation.

[0006] Another purpose of the instant invention is of providing a possibility of recovery of the anchoring in case such a recovery is required.

[0007] In order to achieve said purpose, an anchoring device for supporting excavations in rock has been provided according to the present invention, which comprises a hollow tube equipped with an external screw-­threading with which a nut and possibly a contrast plate are associated, characterized in that said hollow tube is provided with a plurality of longitudinal openings passing through the thickness of the tube wall up to reach the inner hollow of said tube, which longitudinal openings are aligned along one or more row(s) on the external side surface of said tube. According to a preferred form of practical embodiment, with said tube one or more section bar(s) is(are) associated, which are provided with contoured teeth suitable for being inserted through said through-openings; with said section bar(s) being capable of being moved to a position in which it(they) is(are) into contact with said tube, or to a position in which said section bar(s) is(are) moved away from said tube, by tightening (i.e., screwing down) of said nut.

[0008] According to a preferred form of practical embodiment, said hollow tube is screw-threaded both internally and externally along its whole length.

[0009] Still according to the present invention, said contoured teeth are inclined in order to favour the sliding.

[0010] Furthermore, said section bar associated with said screw-threaded tube substantially is "T"-shaped tube with either flat or bent flange, and with a blanked web in order to obtain the toothing; according to a possible form of practical embodiment, the section bar can be replaced by a blanked flat bar with the same toothing, or by other adaptable section bars.

[0011] The technical characteristics and further advantages of the present invention will be clearer from the following disclosure made by referring to the hereto attached drawing table, in which:

Figure 1 shows a partially sectional view of an anchoring device according to the present invention, inserted inside a bore through the rock.

Figure 2 shows a sectional view of the anchoring device made along the path line II-II of Figure 1.

Figure 3 shows a sectional view of another form of practical embodiment of the anchoring device according to the present invention, and

Figure 4 shows a sectional view of the anchoring device made according to the path line IV-IV of Figure 3.

[0012] Referring to the figures, with the reference numeral 10 a device according to the present invention is generally indicated, which is constituted by a hollow, screw-threaded tube 11 with which a section bar 12 is associated. The tube 11 is provided with a nut 13 which supports a plate 14 and is engaged onto a screw-threading 15 provided on the external side surface of the tube 11. Furthermore, according to a preferred form of practical embodiment the tube 11 can be also provided with an internal screw-threading, and the screw-threadings -- i.e., both the internal and the external one -- make it possible joints to be accomplished in order to extend the anchoring, e.g., by means of either internal or external sleeves.

[0013] According to a preferred form of practical embodiment, the internal screw-threading and the external screw-threding are of the same type, and run along the whole length of the tube 11. Along the side surface of the tube 11 a plurality of through openings 16 are provided arranged according to one or more alignment row(s) and spaced apart from each other, at a preestablished distance. The teeth 17 protruding from the section bar 12 and respectively, in case of a plurality of alignment rows, protruding from a plurality of section bars 12, slide inside said openings.

[0014] According to a referred form of practical embodiment, the section bar 12 is a "T"-shaped section bar in which the teeth 17 are provided by blanking from the web, or by other systems, and in which the flanges 18 are either flat or bent so as to match the bending of the tube 11; the teeth 17 furthermore display an inclined portion. In special cases, the section bar 12 could be constituted by a flat bar without flanges, so contoured as to be provided with the toothing, like the above said "T"-shaped section bar.

[0015] In its resting position, the anchoring device 10 according to the present invention has its section bar 12 approached to the tube 11 in such a way that the teeth 17 are inserted inside the openings 16 and the flanges 18 are into contact with the outer surface of the tube 11; the section bar 11 will be retained in said resting position by means of elastic rings, either of metal or of rubber.

[0016] According to a preferred form of practical embodiment, with the use of one single section bar, by acting on the nut 13, i.e., by screwing it down, said nut, and possibly the plate 14 will come into contact with the end of the section bar 12, pushing this latter upwards. In this way, the contoured teeth 17 inserted through the openings 16, owing to their inclination, will cause the section bar to move more and more away from the tube as said nut 13 gets tightened.

[0017] When the nut is completely tightened, the section bar will be into contact with the wall 30 of the bore on a side of said bore -- indicated with the reference numeral 31 in the figures -- and the tube will be into contact with said wall 30 on the opposite side.

[0018] According to another form of practical embodiment in which the section bars are at least two, the contact will take place on one side between the tube and the wall of the bore and on the other side between the section bars and the wall of the bore; in case three section bars are used, the contact with the walls of the bore will take place through the section bars only.

[0019] In this way, a contact is accomplished between the rock and the anchoring, which contact takes place along the whole length of the anchoring, and not at the ends of the anchoring only. Furthermore, the contact takes place immediately along the whole length of the anchoring, and packing the bore with injection materials is no longer necessary; in many cases, the anchoring device can be recovered in a still untouched condition.

[0020] The anchoring device according to the present invention makes it furthermore possible materials to be injected through the hollow tube in case the digging conditions so require; obviously, in this case, the recovery of the anchoring device will be no longer possible.

[0021] A not least advantage is the possibility of prolonging said screw-threaded tubes by using the inner threading or the outer threading, by means of which suitable jointing devices can be connected.

[0022] The present invention has been disclosed for merely illustrative and non-limitative purposes, by referring to the figures of the hereto attached dra wing table, and it should be understood that modifications and changes can be supplied by those skilled in the art, without anyway departing from the scope of protection of the same invention.

Claims

1. Anchoring device for supporting excavations in rock comprising a hollow, screw-threaded tube with which a nut and possibly a contrast plate are associated, characterized in that said hollow tube is provided with a plurality of longitudinal openings passing aligned along one or more alignment row(s) along the external side surface of said tube, with said tube one or more section bar(s) being associated, which are provided with contoured teeth suitable for being inserted inside said through-openings, with said section bar(s) being capable of moving to a position of contact with said tube, or to a position in which said section bar(s) is(are) moved away from said tube by means of the tightening (i.e., screwing down) of said nut and the consequent sliding of said inclined tooth through said through-openings.

2. Anchoring device according to claim 1, characterized in that said hollow screw-threaded tube is externally threaded either along its whole length, or partially.

3. Anchoring device according to claim 1, characterized in that said hollow screw-threaded tube is externally or internally threaded either along its whole length, or partially.

4. Anchoring device according to claim 1, characterized in that said contoured teeth are inclined.

5. Anchoring device according to claim 1, characterized in that said teeth are contoured in such a way as to remain hooked to the hollow tube when they are in the non-expansion step.

6. Anchoring device according to claim 1, characterized in that said section bar associated with said screw-threaded tube substantially is a "T" shaped section bar with flat or bent flanges and a toothed web.

7. Anchoring device according to claim 6, characterized in that instead of the "T"-shaped section bar another type of section bar can be used, which is so machined as to be provided with the teeth in order to perform the same task as of said "T"-shaped section bar.

8. Anchoring device according to claim 1, characterized in that said longitudinal through-openings have all the same size.

9. Anchoring device according to claim 1, characterized in that said longitudinal openings are arranged at same distiances, along one or more alignment rows, along the side surface of said tube.

10. Anchoring device according to claim 1, characterized in that all of said contoured teeth have the same inclination and the same hooking contour.

11. Anchoring device according to claim 1, characterized in that said contoured teeth are arranged at equal distances, with said distances between said teeth being analogous to the distances between said openings.

12. Anchoring device according to claim 1, characterized in that the number of the section bars with the toothings, as well as the alignment rows of the pluralities of openings can be more than one, and said section bars can be arranged on the circumference of said hollow tube according to different radial angles.

13. Anchoring device according to claim 1, characterized in that said hollow tube can be provided with said screw-threading by roll forming, with an internal screw-threading being consequently obtained, which is negative relatively to the external screw-­threading.

Drawing