WO2006014073A1

WO2006014073A1 - Rock bolt anchoring device

Info

Publication number: WO2006014073A1
Application number: PCT/KR2005/002520
Authority: WO
Inventors: Heung-Man Kim
Original assignee: Heung-Man Kim
Priority date: 2004-08-06
Filing date: 2005-08-02
Publication date: 2006-02-09
Also published as: KR100602906B1; KR20060013192A

Abstract

Disclosed herein is a rock bolt anchoring device capable of stably positioning a rock bolt in a drilled hole in the beginning of a construction operation and also of preventing a filler in the drilled hole from leaking from an entrance of the drilled hole.

Description

ROCK BOLT ANCHORING DEVICE

Technical Field

[1] The present invention relates to a rock bolt anchoring device capable of easily anchoring a rock bolt, for use in the construction of a tunnel to reinforce the structure of the tunnel, in a base rock and, more particularly, to a rock bolt anchoring device capable of stably anchoring a rock bolt without the risk of separation of the rock bolt from a drilled hole of a base rock and also of preventing the leakage of a filler in the drilled hole.

Background Art

[2] Considering a general tunnel construction procedure, primarily, a tunnel is roughly bored via blasting or excavation. Then, a plurality of rock bolts are anchored into a base rock for the reinforcement of the tunnel structure. Here, the rock bolts are spaced apart from one another by a constant distance. Then, concrete is cast to an inner wall surface of the tunnel to construct a reinforcement wall.

[3] Now, the anchoring procedure of the rock bolts into the base rock for the con¬ struction of the reinforcement wall will be explained in more detail with reference to FIGS. Ia to Ic. To anchor the rock bolts into the base rock, the base rock is drilled with a plurality of holes for the insertion of the rock bolts using a drilling machine, etc.

[4] After a filler 17 is injected into the drilled holes 13 formed in several locations of the tunnel base rock 12, the rock bolts 14 are inserted into the drilled holes 13, re¬ spectively. Then, a reinforcing plate 18 is fastened to a distal end of each of the rock bolts 14 by means of a nut 19. Finally, concrete is cast to the tunnel inner wall surface to form the reinforcement wall 20.

[5] The filler 17, which is injected into the drilled holes 13 to fix the rock bolts 14 in the drilled holes 13, generally include two main examples. One of them is mortar which has been mainly used as the filler 17, and the other one is resin.

[6] In a method of using the mortar, the rock bolts 14 may be inserted into the respective drilled holes 13 before or after injecting the mortar into the drilled holes 13. In this case, the rock bolts 14 are anchored in the rock wall of the tunnel via the hardening of the mortar. This method, however, has several problems in that the mortar takes a relatively long time to harden, requires a great deal of equipment and labor, and results in an unclean work environment.

[7] On the other hand, in a method of using the resin, a resin ampoule 16 is inserted into a respective one of the drilled holes 13. The resin ampoule 16 is designed so that a foaming agent and an addition agent are separately received therein. As the rock bolt 14 is inserted into the drilled hole 13, the glass ampoule 16 is broken, causing reactions of the foaming agent and the addition agent with resin. Thereby, the resin is simul¬ taneously foamed and hardened, allowing the rock bolt 14 to be anchored in the drilled hole 13. Disclosure of Invention

Technical Problem

[8] However, the method of using the resin also has the several problems. Firstly, a great amount of resin foam may leak from the drilled holes by an internal pressure. Here, the internal pressure is created in the drilled hole during the foaming and hardening of the resin. Secondly, it is necessary to manually support the rock bolts so as not to be pushed out from the drilled holes by the internal pressure until the resin foam is sufficiently hardened. Thirdly, when the drilled hole is located at the ceiling of the tunnel, broken pieces of the glass ampoule fall from the ceiling, threatening worker safety.

Technical Solution

[9] Therefore, the present invention has been made in view of the above problems, and it is an object of the present invention to provide a rock bolt anchoring device capable of stably positioning a rock bolt in a drilled hole in the beginning of a construction operation and also of preventing a filler in the drilled hole from leaking from an entrance of the drilled hole.

[10] It is another object of the present invention to provide a rock bolt anchoring device capable of anchoring a rock bolt in the center of a drilled hole while preventing the rock bolt from being eccentrically located in the drilled hole.

[11] In accordance with an aspect of the present invention, the above and other objects can be accomplished by the provision of a rock bolt anchoring device for anchoring a rock bolt at an entrance of a drilled hole formed in a tunnel base rock to thereby allow the rock bolt to be inserted into the drilled hole and be fixedly mounted in the drilled hole by interposing a filler, comprising: a cylindrical body including a plurality of downwardly inclined external protrusions formed at an outer circumferential surface thereof, a plurality of upwardly inclined internal protrusions formed at an inner cir¬ cumferential surface thereof, adjacent ones of the internal protrusions having a pre¬ determined constant height difference, and an outwardly protruding flange formed at a lower end thereof; a flap coupled to the flange of the body and including a rim portion formed along a circumference thereof, a groove defined in the rim portion for the insertion of the flange of the body, a guiding portion located on the inward side of the groove and having a guiding end surface to guide the insertion of the rock bolt, and a centrally formed through-opening; and a cylindrical guide having a predetermined thickness and configured to be inserted in a lower region of the body to be disposed on the flap, a lower surface of the guide having an inclination to correspond to the guiding portion of the flap.

[12] Preferably, the plurality of internal protrusions, formed at the inner circumferential surface of the body, may be located at different heights from one another to correspond to respective pitches of rock bolt threads.

[13] Preferably, the flap may be made of a synthetic resin material, such as rubber, to ensure easy handling of the flap and to allow the flap to come into close contact with the rock bolt when the rock bolt is inserted into the through-opening.

[14] Preferably, the cylindrical guide having the predetermined thickness may have a flat upper surface perpendicular to a circumferential surface of the guide, and the inclined lower surface configured to come into close contact with the guiding portion of the flap.

Advantageous Effects

[15] As will be easily expected, in this case, part of the resin foam may leak out of the drilled hole 13 by an internal pressure of the drilled hole 13. Also, when the drilled hole 13 is located at the ceiling of the tunnel, the broken pieces of the glass ampoule 16 may fall from the entrance of the drilled hole 13. However, the rock bolt anchoring device of the present invention is able to restrict the leakage of the resin foam from the entrance of the drilled hole 13. That is, the leakage of the resin foam from the outside of the rock bolt anchoring device can be completely intercepted by the outwardly protruding rim portion of the rock bolt anchoring device. Also, since the space between the rock bolt 14 and the rock bolt anchoring device is sufficiently narrowed, the leakage of the resin foam from the interior of the rock bolt anchoring device can be primarily restricted and retarded by the narrow space. Even when the resin foam passes through the narrow space, the leakage of the resin foam can be secondarily restricted by the guiding portion 34 that comes into close contact with the circumference of the rock bolt 14. In this way, the leakage of the excessive resin foam beyond an inevitable surplus amount can be prevented.

[16] In the present invention, also, since the rock bolt anchoring device completely seals the entrance of the drilled hole, there is no risk of falling of the broken pieces of the glass ampoule even when the rock bolt is anchored in the drilled hole of the ceiling.

[17] By preventing the excessive resin foam beyond the inevitable surplus amount from leaking from the drilled hole 13, the resin foam is hardened in a tightly pressed state in the drilled hole 13. This enables the rock bolt 14 to be anchored in the drilled hole 13 with a sufficient pressure and completely prevents the falling of the broken glass pieces. Consequently, prevention of the leakage of the excessive resin foam and impurities, such as the broken pieces, ensures a clean work environment.

[18] After the rock bolt 14 is completely inserted into the drilled hole 13, the reinforcing plate 18 and the nut 19 are fastened to the rock bolt 14. In this way, the anchoring of the rock bolt 14 into the drilled hole 13 is completed. Then, concrete is cast to the inner wall surface of the tunnel, completing construction of the reinforcement wall.

Description of Drawings [19] The above and other objects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which: [20] FIGS. Ia to Ic are views illustrating a procedure of anchoring a rock bolt into a tunnel base rock; [21] FlG. 2 is a perspective view of a rock bolt anchoring device according to the present invention; [22] FlG. 3 is a side sectional view of the rock bolt anchoring device according to the present invention; [23] FlG. 4 is an exploded perspective view of the rock bolt anchoring device according to the present invention; [24] FlG. 5 is a view illustrating an unrolled body of the rock bolt anchoring device according to the present invention, which shows a positional relationship between internal protrusions; [25] FlG. 6 is a sectional view illustrating a flap of the rock bolt anchoring device according to the present invention; [26] FlG. 7 is a sectional view illustrating the rock bolt anchoring device according to the present invention, mounted in a base rock; and [27] FlG. 8 is a plan view of the rock bolt anchoring device according to the present invention.

Best Mode [28] Now, the configuration of a rock bolt anchoring device according to the present invention will be described with reference to the accompanying drawings. [29] Referring to FIGS. 2 to 4, the rock bolt anchoring device of the present invention comprises, as main elements, a cylindrical body 21, a flap 31 provided at a lower end of the body 21, and a guide 41 inserted in a lower region of the body 21 to be disposed on the flap 31. [30] The body 21 is made of a carbon steel plate, so that the body 21 is able to maintain a predetermined strength sufficient to support a rock bolt 14 in a drilled hole 13 of a base rock 12 and to create a certain elasticity when the rock bolt anchoring device is inserted into the base rock 12 or the rock bolt 14 is inserted into the rock bolt anchoring device. [31] The body 21 is formed by rolling the steel plate into a cylindrical shape, and is provided, at a certain location thereof, with a slot 22 having a predetermined width. The slot 22 vertically extends throughout the body 21 from an upper end to a lower end of the body 21. The presence of the slot 22 allows the body 21 to flexibly suit different diameters of drilled holes 13 and facilitates the insertion of the body 21. [32] The body 21 is further provided with a plurality of external and internal protrusions

23 and 24 at outer and inner circumferential surfaces thereof. The external and internal protrusions 23 and 24 of the body 21 are formed by cutting certain portions of the body 21 so that the external protrusions 23 are inclined downward and the internal protrusions 24 are inclined upward.

[33] Specifically, the plurality of external protrusions 23, formed at the outer circum¬ ferential surface of the body 21, serves to anchor the rock bolt anchoring device in the drilled hole 13. Since the external protrusions 23 are spaced apart from one another by a predetermined constant distance and are inclined downward, they are capable of ensuring easy insertion of the rock bolt anchoring device into the drilled hole 13 while making it difficult to remove the rock bolt anchoring device from the drilled hole 13. This effectively prevents the rock bolt anchoring device of the present invention from being separated from the drilled hole 13 of the base rock 12. Also, since the external protrusions 23 are formed by cutting certain portions of the body 21 made of the steel plate, they can exhibit an elasticity sufficient to elastically support the body 21 in a gap defined between the body 21 and the drilled hole 13.

[34] On the other hand, the internal protrusions 24, formed at the inner circumferential surface of the body 21, serve to anchor the rock bolt 14 in the rock bolt anchoring device. The internal protrusions 24 are spaced apart from one another by a pre¬ determined constant distance and are inclined upward, so that distal ends thereof are engaged with threads 15 formed at a circumference of the rock bolt 14. With this con¬ figuration, the internal protrusions 24 are capable of allowing the rock bolt 14 to be fixed in the rock bolt anchoring device, which is mounted in the drilled hole, without the risk of separation from the drilled hole.

[35] Here, the upwardly inclined internal protrusions 24 of the cylindrical body 21 are located at different heights from one another so that the distal ends of the respective internal protrusions 24 are positioned in respective pitches of the threads 15 formed at the circumference of the rock bolt 14. That is, in a state wherein the rock bolt 14 is fixed in the rock bolt anchoring device, the distal ends of the internal protrusions 24 support the threads 15 formed at the circumference of the rock bolt 14. Thus, in order to allow the distal ends of the respective internal protrusions 24 to correspond to the respective pitches of the threads 15, the distal ends of the adjacent internal protrusions

24 must be located at the different heights from one another. Referring to FlG. 5 il¬ lustrating the unrolled state of the cylindrical body 21, the positional relationship of the internal protrusions 24 can be easily understood. In FlG. 5, a dashed line, which connects the distal ends of the internal protrusions 24 to one another, is a straight line having a certain inclination.

[36] At the lower end of the body 21 configured as stated above is provided a flange 25.

The flange 25 is formed by outwardly bending the lower end of the body 21 to have a predetermined width, and serves to reinforce the strength of the body 21. To the flange 25 is coupled the flap 31, which will be explained hereinafter.

[37] Summarizing the configuration of the body 21, the body 21 is formed by rolling the steel plate to have the cylindrical shape, and has the plurality of external and internal protrusions 23 and 24 formed at the outer and inner circumferential surfaces thereof, and the flange 25 formed at the lower end thereof.

[38] The flap 31 is located underneath the body 21 to be coupled to the flange 25.

[39] The flap 31 is made of a synthetic resin material, such as rubber, to ensure easy handling thereof. Considering the configuration of the flap 31 with reference to FlG. 6, it includes a rim portion 32 on the circumference thereof, a groove 33 defined in the rim portion 32 for the insertion of the flange 25 of the body 21, and a guiding portion 34 located on the inward side of the groove 33 and configured to surround the cir¬ cumference of the rock bolt 14. The guiding portion 34 is centrally hollowed, and has a guiding end surface to guide the initial entry of the rock bolt 14.

[40] The flap 31 configured as stated above is coupled to the lower end of the body 21 as the flange 25 of the body 21 is inserted into the groove 33 of the flap 31.

[41] The flap 31 also includes a center through-opening 35 for the penetration of the rock bolt 14. When the rock bolt 14 is penetrated through the opening 35, the guiding portion 34, formed around the opening 35, surrounds the circumference of the rock bolt 14. In this case, the rock bolt 14 is able to be easily inserted into the rock bolt anchoring device under the guidance of the guiding surface formed at the end of the guiding portion 34. In a completely inserted state of the rock bolt 14, also, the guiding end surface of the guiding portion 34 closely surrounds the rock bolt 14, thereby preventing the leakage of a filler or impurities, such as broken pieces of a glass ampoule, from the interior of the drilled hole. Here, forming the opening 35 on the inward side of the guiding portion 34 effectively prevents the flap 31 from being separated from the flange 25 of the body 21 during insertion of the rock bolt 14 into the drilled hole. One might propose that, after forming the center portion of the flap 31 into a conical or semispherical shape, the center portion is incised at one or more portions to insert the rock bolt 14. However, when resin is used as a filler, the respective incised portions excessively surround the rock bolt 14 because the rock bolt 14 is inserted into the drilled hole while being rotated at a high speed, causing unin¬ tentional separation of the flap 31 from the flange 25 of the body 21 during the insertion of the rock bolt 14 into the drilled hole.

[42] Meanwhile, prior to coupling the flange 25 to the flap 31, the guide 41 is inserted into the lower region of the body 21.

[43] The guide 41 has a cylinder shape having a predetermined thickness. An upper surface 42 of the guide 41 forms a plane perpendicular to a circumferential surface of the guide 41, while a lower surface 43 of the guide 41 forms an inclined plane having the same inclination as the guiding portion 34 of the flap 31. Also, a thickness of the guide 41 is determined to define an appropriate gap between an inner diameter plane of the body 21 and an outer diameter plane of the rock bolt 14 inserted in the body 21. This effectively prevents the rock bolt 14 from deviating from the center axis of the body 21 during rotating insertion thereof. The inclined plane, formed by the lower surface 43 of the guide 41, is inclined upward from an outer edge to an inner edge thereof.

Mode for Invention

[44]

[45] Now, the operation of the rock bolt anchoring device according to the present invention configured as stated above will be explained.

[46] After the rock bolt anchoring device of the present invention, which includes the body 21, the flap 31, and the guide 41, is inserted into the entrance of the drilled hole to thereby be stably mounted in the drilled hole, the rock bolt 14 is inserted into the rock bolt anchoring device to be fixed therein.

[47] Explaining the above in greater detail, first, the hole 13 is drilled in the base rock by a certain depth from the inner wall surface of the tunnel in the same manner as the prior art.

[48] Here, prior to inserting the rock bolt anchoring device into the drilled hole 13, a resin ampoule 16 is inserted into the drilled hole 13. By virtue of the downwardly inclined external protrusions 23 and the upwardly inclined internal protrusions 24 formed at the outer and inner circumferential surfaces of the body 21, the resin ampoule 16 is able to be caught by the anchoring device so as not to fall from the anchoring device even before the rock bolt 14 is inserted into the rock bolt anchoring device.

[49] As will be easily expected, the diameter of the drilled hole 13 is variable per different locations thereof, and may have an uneven interior space. However, by virtue of the slot 22 and the elastic external protrusions 23 of the body 21, the rock bolt anchoring device of the present invention is able to flexibly suit the uneven interior volume of the drilled hole 13 when it is gradually inserted into the drilled hole 13.

[50] If the rock bolt anchoring device is completely mounted in the drilled hole 13, the rock bolt 14 is inserted into the rock bolt anchoring device. In this case, a leading end of the rock bolt 14 is initially guided by the guiding portion 34 of the flap 31 so as to be inserted into the rock bolt anchoring device. In succession, the insertion of the rock bolt 14 is advanced through the guide 41 so that the rock bolt 14 can maintain an ap¬ propriate gap with the rock bolt anchoring device without deviating from the center axis of the rock bolt anchoring device. The leading end of the rock bolt 14, having passed through the guide 41, comes into contact with the internal protrusions 24 formed at the inner circumferential surface of the body 21. Immediately after the leading end thereof passes through the body 21 of the rock bolt anchoring device, the rock bolt 14 is rotated at a high speed by a drill while coming into contact with the internal protrusions 24, thereby being inserted into the drilled hole 13.

[51] When the rock bolt 14 is inserted into the drilled hole 13 while being rotated at the high speed, conventionally, the rock bolt 14 may be eccentrically moved, causing severe fluctuation thereof. However, in the present invention, by virtue of the guide 41 inserted in the lower region of the rock bolt anchoring device, the insertion of the rock bolt 14 is able to be straightly guided, eliminating the risk of fluctuation due to the eccentric disposition thereof.

[52] Also, in a state wherein the rock bolt 14 is completely inserted in the rock bolt anchoring device, the threads 15 formed at the rock bolt 14 are supported, at the lower side thereof, by the upwardly inclined internal protrusions 24 of the body 21. This has the effect of preventing the separation of the rock bolt 14 from the rock bolt anchoring device. Also, since the rock bolt anchoring device is fixed in the drilled hole 13 by the external protrusions 23 of the body 21, consequently, the rock bolt 14 is able to be anchored in the drilled hole 13.

[53] In the present invention, since the internal protrusions 24 of the body 21 are formed at the different heights to correspond to the respective pitches of the threads 15 of the rock bolt 14, when the rock bolt 14 is inserted into the drilled hole 13 while being rotated at the high speed, the ends of the upwardly inclined internal protrusions 24 temporarily come close to the body 21 by the threads 15 of the rock bolt 14. This has the effect of reducing the resistance of the internal protrusions 24 caused at the time when the rock bolt 14 enters the body 21. Also, since the rock bolt 14 is able to be straightly inserted by the guide 41 without the risk of fluctuation, rotational friction of the rock bolt 14 is able to be minimized. Therefore, upon the high-speed rotation of the rock bolt 14, the rock bolt 14 is engaged with the rock bolt anchoring device, thereby preventing unassisted rotation of the rock bolt anchoring device in the drilled hole 13.

[54] Meanwhile, as the rock bolt 14 is inserted into the drilled hole 13, the resin ampoule 16, which has inserted in the drilled hole 13, is broken by the leading end of the rock bolt 14. Thereby, resin, received in the resin ampoule 16, chemically reacts with a foaming agent, etc. received in the resin ampoule 16, producing a resin foam. As the resulting resin foam fills a space between the rock bolt 14 and the drilled hole 13, the rock bolt 14 is able to be anchored in the drilled hole 13 of the base rock.

Industrial Applicability

[55]

[56] As is apparent from the above description, the rock bolt anchoring device of the present invention has the following effects.

[57] Firstly, when a rock bolt is initially inserted into a drilled hole of a base rock, the rock bolt anchoring device of the present invention can ensure easy insertion of the rock bolt under the operation of a flap and a guide thereof. Further, after completing insertion of the rock bolt, the rock bolt anchoring device of the present invention can completely prevent the rock bolt from being separated from the drilled hole by supporting the rock bolt using a plurality of internal protrusions thereof.

[58] Furthermore, the leakage of rock fragments, broken pieces of a glass resin ampoule, resin foam, etc, from the drilled hole can be completely prevented by the flap, guide, and rim portion of the anchoring device. This improves the stability of con¬ struction work. Finally, according to the present invention, only the inevitable minimum surplus amount of resin foam leaks from the drilled hole, allowing the resin foam to be hardened in a tightly filled state in the drilled hole. As a result, the rock bolt can be anchored in the drilled hole with a sufficient pressure.

[59] Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modi¬ fications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.

Sequence Listing

[60]

Claims

[1] A rock bolt anchoring device for anchoring a rock bolt at an entrance of a drilled hole formed in a tunnel base rock to thereby allow the rock bolt to be inserted into the drilled hole and be fixedly mounted in the drilled hole by interposing a filler, comprising: a cylindrical body including a plurality of downwardly inclined external protrusions formed at an outer circumferential surface thereof, a plurality of upwardly inclined internal protrusions formed at an inner circumferential surface thereof, adjacent ones of the internal protrusions having a predetermined constant height difference, and an outwardly protruding flange formed at a lower end thereof; a flap coupled to the flange of the body and including a rim portion formed along a circumference thereof, a groove defined in the rim portion for the insertion of the flange of the body, a guiding portion located on the inward side of the groove and having a guiding end surface to guide the insertion of the rock bolt, and a centrally formed through-opening; and a cylindrical guide having a predetermined thickness and configured to be inserted in a lower region of the body to be disposed on the flap, a lower surface of the guide having an inclination to correspond to the guiding portion of the flap.

[2] The device as set forth in claim 1, wherein the plurality of internal protrusions, formed at the inner circumferential surface of the body, is located at different heights from one another to correspond to respective pitches of rock bolt threads.

[3] The device as set forth in claim 1, wherein the flap is made of a synthetic resin material, such as rubber, to ensure easy handling of the flap and to allow the flap to come into close contact with the rock bolt when the rock bolt is inserted into the through-opening.

[4] The device as set forth in claim 1, wherein the cylindrical guide having the predetermined thickness has a flat upper surface perpendicular to a circum¬ ferential surface of the guide, and the inclined lower surface configured to come into close contact with the guiding portion of the flap.