WO2008088171A1

WO2008088171A1 - Anchor

Info

Publication number: WO2008088171A1
Application number: PCT/KR2008/000286
Authority: WO
Inventors: Jae-Man Park; Young-Jun Park; Gyu-Jeom Jung; Byoung-Woo Shin; Yoon-Jine Jung; Keum-Sik Kang; Chul-Yeong Kim; Sung-Il Yoon; Pyong-Kyong Uh; Hwa-Yong Lee
Original assignee: Jae-Man Park; Young-Jun Park; Gyu-Jeom Jung; Byoung-Woo Shin; Yoon-Jine Jung; Keum-Sik Kang; Chul-Yeong Kim; Sung-Il Yoon; Pyong-Kyong Uh; Hwa-Yong Lee
Priority date: 2007-01-17
Filing date: 2008-01-17
Publication date: 2008-07-24

Abstract

Provided is an anchor. The anchor including an anchor main body coupled to a plurality of tension members longitudinally disposed in one direction at its one end to be buried in a hole, includes: an anchor extension body including a hollow-shaped case coupled to the anchor main body to surround an outer periphery of the anchor main body, and a plurality of extensions disposed in a circumferential direction of the case to be spaced apart from each other, each of which extends from an end of the case in a longitudinal direction of the anchor main body; and an extension means for widening ends of the extensions of the anchor extension body toward an inner periphery of the hole such that the extensions press against the inner periphery of the hole to enlarge the hole.

Description

ANCHOR

Technical Field

[1] The present invention relates to an anchor buried underground to reinforce a slope, and more particularly, to an anchor body disposed at a tip of an anchor to be coupled to a tension member. Background Art

[2] Generally, slopes such as mountains must be developed somewhat in order to construct roads or various housing complexes. For this purpose, slope reinforcement methods are widely used to prevent the slopes from collapsing or sliding. Such slope reinforcement methods are generally classified into an active force reduction method, a resistance reinforcement method, and a surface protection method, depending on the purpose of construction. Among these methods, the resistance reinforcement method may use things such as lock bolts, ground anchors, soil nails, stepped retaining walls, and so on.

[3] The anchor method is widely used in a reinforcement structure for reinforcing the ground as well as supporting structures such as buildings, bridges, and so on.

[4] An anchor includes an anchor body, a tension member, and an anchor head. In the anchor construction, a hole is formed in the ground to have a predetermined depth and diameter, the anchor body coupled to the tension member is inserted thereinto, and the hole is filled with a grouting material such as cement paste. When the grouting material is cured, tension is applied to the tension member by a predetermined load, and the anchor head is stably anchored. The tension member is generally formed of a prestressed concrete (PC) strand (steel strand), or a steel rod. A tension member fixing structure mainly employs a wedge method using a wedge cone in the case of the steel strand, and a nut method in the case of the steel rod.

[5] In reinforcement of the slope using the anchor constituted as described above, in order to obtain good ground anchor force, a deep end of the hole in which the anchor body is disposed must have a larger diameter than the other parts of the hole to increase anchor force between the anchor body and the ground.

[6] A conventional anchor for increasing anchor force between an anchor body and the ground is shown in FIG. 1. FIG. 1 is a schematic view illustrating the conventional anchor. The anchor shown in FIG. 1 is disclosed in Korean Patent Laid-Open Publication No. 2006-0122346. Referring to FIG. 1, the conventional anchor 9 includes an anchor main body 1 buried underground, and a plurality of tension members 2 coupled to the anchor main body 1. In addition, a plurality of blades 3 are installed at the anchor main body 1 to insert into and project from the anchor main body 1. When the blades 3 project therefrom, the blades 3 pierce a hole h to be anchored in the ground. Meanwhile, springs (not shown) interposed between the anchor main body 1 and the blades 3 to resiliently bias the blades 3 outwardly, thus projecting the blades 3.

[7] However, it is almost impossible to push the blades 3 using power of the springs of the anchor 9 such that the blades 3 can pierce an inner wall of the hole h. Even though the blades 3 are pushed, a piercing depth is shallow, making it difficult to secure the anchor force between the anchor main body 1 and the ground. In addition, since the above constitution cannot enlarge the diameter of the hole h, in which the anchor main body 1 is disposed, it is impossible to obtain good anchor force with the anchor 9. Disclosure of Invention Technical Problem

[8] In order to solve the foregoing and/or other problems, an object of the present invention is to provide an improved anchor capable of enlarging a diameter of a deep end of a hole, and increasing anchor force between the anchor and the ground. Technical Solution

[9] One aspect of the present invention provides an anchor including an anchor main body coupled to a plurality of tension members longitudinally disposed in one direction at one end to be buried in a hole, and further including an anchor extension body including: a hollow-shaped case coupled to the anchor main body to surround an outer periphery of the anchor main body, and a plurality of extensions disposed in a circumferential direction of the case to be spaced apart from each other, each of which extends from an end of the case in a longitudinal direction of the anchor main body; and an extension means for widening ends of the extensions of the anchor extension body toward an inner periphery of the hole such that the extensions press against the inner periphery of the hole to enlarge the hole.

Advantageous Effects

[10] As can be seen from the foregoing, using an anchor in accordance with the present invention, it is possible to increase anchor force between the anchor and the ground and form a spherical structure having a large diameter at a deep end of the hole, thereby stably reinforcing the slope. Brief Description of the Drawings

[11] The above and other objects, features and advantages of the present invention will be more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which:

[12] FIG. 1 is a schematic perspective view of a conventional anchor; [13] FIG. 2 is a schematic exploded perspective view of an anchor in accordance with an exemplary embodiment of the present invention;

[14] FIG. 3 is a schematic perspective view of the anchor of FIG. 2 after assembly;

[15] FIG. 4 is a schematic cross-sectional view taken along line IV-IV of FIG. 3;

[16] FIG. 5 is a schematic cross-sectional view taken along line V-V of FIG. 3;

[17] FIG. 6 is a schematic view illustrating an energy transmission apparatus employed in an exemplary embodiment in accordance with the present invention;

[18] FIG. 7 is a schematic flowchart of an anchor construction method in accordance with an exemplary embodiment of the present invention;

[19] FIG. 8 is a view illustrating a hole piercing step to a hole enlarging step;

[20] FIG. 9 is a view illustrating a filling step and a tension anchoring step;

[21] FIG. 10 is a schematic exploded perspective view of an anchor in accordance with another exemplary embodiment of the present invention;

[22] FIG. 11 is a schematic perspective view of the anchor of FIG. 10 after assembly;

[23] FIG. 12 is a schematic cross-sectional view taken along line XII-XII of FIG. 11; and

[24] FIG. 13 is a cross-sectional view of a raised state of an extension cap of FIG. 12.

Mode for the Invention

[25] Hereinafter, anchors in accordance with exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[26] FIG. 2 is a schematic exploded perspective view of an anchor in accordance with an exemplary embodiment of the present invention, FIG. 3 is a schematic perspective view of the anchor of FIG. 2 after assembly, FIG. 4 is a schematic cross-sectional view taken along line IV-IV of FIG. 3, and FIG. 5 is a schematic cross-sectional view taken along line V-V of FIG. 3.

[27] Referring to FIGS. 2 to 5, an anchor 100 in accordance with an exemplary embodiment of the present invention includes an anchor main body 10, and an anchor extension body 30.

[28] The anchor main body 10, which is well known, is inserted into a hole h prepared in the ground to be buried underground. The anchor main body 10, to which a plurality of tension members w are coupled, is inserted into the hole h. The tension members w may be removed after construction of the anchor depending on the type of the anchor main body 10. The tension members w are generally formed of a plurality of PC strands or steel rods. The tension members w are surrounded by a covering material 12. The structure for fixing the tension members w employs a wedge method using a wedge cone (not shown) in the case of the PC strands, and a nut method (not shown) in the case of the steel rods. Meanwhile, an inner member 11 is coupled to a center part of the anchor main body 10.

[29] The anchor extension body 30 having a hollow shape is inserted into the anchor main body 10 and coupled thereto. The anchor extension body 30 includes a case 31 and a plurality of extensions 32. The case 31 is inserted into an upper end of the inner member 11 and fixed thereto. The case 31 has a plurality of through-holes 39 formed in its upper surface, and the tension members w coupled to the anchor main body 10 pass through the through-holes 39. The extensions 32 extend downward from the case

31 in a longitudinal direction of the case 31. Slits 33 are formed between the extensions 32 to space the extensions 32 from each other. In this exemplary embodiment, four extensions 32 are disposed in a circumferential direction of the case 31. As described above, the extensions 32 may be spaced apart from each other, or interconnected by connection parts (not shown). However, when the connection parts (not shown) exist, the connection parts must be able to be readily broken down by a thermite reaction between metal mixtures, which will be described below. That is, the connection parts should be very weakly coupled to the extensions.

[30] Projection piece 38 should be formed at an outer surface of the extensions 32. Each extensions 32 have A plurality of projection pieces 38. The projection pieces 38 project in a direction intersecting the longitudinal direction of the anchor extension body 30. More specifically, each projection piece 38 includes a vertical part 36 and an inclination part 37. The vertical part 36 is disposed perpendicular to the longitudinal direction of the anchor extension body 30. The inclination part 37 is disposed to form a predetermined angle with an end of the vertical part 36. Therefore, the predetermined angle between the inclination part 37 and the vertical part 36 is an acute angle. In this exemplary embodiment, two projection pieces 38 are disposed at each extension 32 of the anchor extension body 30.

[31] In addition, mounting frames 35 are provided at inner surfaces of the extensions 32 of the anchor extension body 30. The mounting frames 35 function to mount a metal mixture m, which will be described, and are installed in a direction intersecting the longitudinal direction of the anchor extension body 30. Meanwhile, the anchor extension body 30 is formed of a metal material such as iron, and so on, and manufactured by a method such as casting, and so on.

[32] The anchor 100 includes an extension means for outwardly widening the extensions

32 of the anchor extension body 30 toward the inner periphery of the hole h.

[33] In this exemplary embodiment, the extension means functions to perform a thermite reaction, and includes a metal mixture m and a power supply 41. The metal mixture m is disposed between the anchor extension body 30 and the anchor main body 10. In this exemplary embodiment, it is mounted on the mounting frames 35 formed inside the extensions 32 of the anchor extension body 30. The powder-type metal mixture m is contained in, for example, fabric pockets, and so on, to be mounted on the mounting frames 35.

[34] The metal mixture m is formed of metal oxide and metal powder. The metal oxide may include copper oxide (CuO), copper dioxide (Cu O), iron oxide (FeO), ferric oxide (Fe O ), magnetite (Fe O ), manganese dioxide (MnO ), chromium potassium oxide (K Cr O ), and so on. In addition, the metal powder may be formed of various materials such as alkaline metal, alkaline earth metal, aluminum (Al), iron (Fe), magnesium (Mg), copper (Cu), and so on. In this exemplary embodiment, the metal powder employs aluminum (Al) which has relatively good reaction heat per unit mass, and the metal oxide employs copper oxide (CuO), which is relatively inexpensive. A mixing ratio thereof is 4g to 5g of copper oxide per Ig of aluminum. In addition, other functional materials may be added, in addition to the metal mixture m. For example, in order to increase a reaction speed of the thermite reaction and induce a complete reaction, a reaction speed enhancing agent, in which a major component formed of low specific gravity and ultra lightweight fine particles such as silicon dioxide (SiO ), aluminum oxide (Al O ), ferric oxide (Fe O ), calcium oxide, and so on, is mixed with aluminum powder having a high calorific value, may be added. Further, in order to reduce noises, prevent continuous explosion due to flame generated from incomplete reaction, and suppress blown-out shot, an electrolyte fluid material, in which halides of alkaline metal or alkaline earth metal, oxysalt, NaCl, and so on, are dissolved in water, may be added.

[35] The total amount of the metal mixture mounted on the anchor extension body 30 may be varied depending on the diameter of the hole h and the material or thickness of the anchor extension body 30, and may be about 1Og to 7Og. However, the total amount may be less than 1Og or more than 7Og.

[36] The thermite reaction caused by the metal mixture m is referred to as a reaction in which the metal oxide is deoxidized by the metal powder such as aluminum. A commercially used mixture of metal mixture and aluminum powder is referred to as a thermite agent. When energy is applied to ignite a thermite agent metal mixture m formed of metal oxide and metal powder, aluminum reduces and extricates copper oxide to form alumina through a strong chemical reaction. In this process, a high reaction temperature of about 3000⁰C and metal vapor pressure are generated for a very short time (several tens of μsec), and an energy of 1207kJ is generated. The thermite reaction formula is as follows:

[37] 2Al + 3CuO + ΔE -> Al 2 O 3 + 1207 kJ

[38] ΔE represents energy for inducing the thermite reaction, which requires about 1OkJ per Ig of aluminum. The energy for inducing the thermite reaction may be electrically applied by a power supply 41, which will be described below, or may be applied by a non-electrical method such as gunpowder. Once the energy ΔE is applied, the metal mixture m performs continuous thermite reactions through a self-sustaining reaction.

[39] Generation of the thermite reaction causes an expansion force such that the extensions 32 of the anchor extension body 30 are bent outward to be widened. The outwardly bent extensions 32 press against the inner periphery of the hole h to enlarge the hole h.

[40] As described above, since the energy ΔE should be transmitted to the metal mixture m to cause the thermite reaction, the extension means of the anchor 100 in accordance with the present invention includes an energy transmission device 40. The energy transmission device may employ an electric type or a non-electric type, similar to the above, but in this exemplary embodiment, the electric type.

[41] FIG. 6 is a schematic view illustrating an energy transmission apparatus employed in an exemplary embodiment in accordance with the present invention. Referring to FIG. 6, the energy transmission device 40 in accordance with an exemplary embodiment of the present invention includes a power supply 41, and two conductive wires 42 and 43. The power supply 41 is disposed outside the hole h, and includes a positive terminal and a negative terminal. The two conductive wires 42 and 43 are electrically connected to the positive terminal and the negative terminal of the power supply 41, and surrounded by a covering material. However, the coating material surrounded at lower ends of the conductive wires 42 and 43 are removed. The lower ends of the conductive wires 42 and 43 are spaced a predetermined distance from each other. The conductive wires 42 and 43 are inserted into the hole h, and disposed adjacent to the metal mixture m through the through-holes 39 of the anchor extension body 30. When electric power is applied to the power supply 41, arc is generated from the lower ends of the conductive wires. The arc acts as the energy ΔE for inducing the thermite reaction to perform the thermite reaction in the metal mixture m.

[42] However, it may also be possible to transmit energy using a heat generating resistor, without generating arc. That is, when the lower ends of the conductive wires 42 and 43 are connected to each other by a heat generating resistor (not shown) having a high resistance value, for example, a tungsten wire or a nichrome wire, and electric power is supplied, high heat is generated due to the wire resistance and the heat acts as energy for causing the thermite reaction.

[43] Hereinafter, an anchor construction method of constructing the anchor constituted as described above will be described. FIG. 7 is a schematic flowchart of an anchor construction method in accordance with an exemplary embodiment of the present invention, and FIGS. 8 and 9 are views illustrating the anchor construction method. FIG. 8 is a view illustrating a hole piercing step to a hole enlarging step, and FIG. 9 is a view illustrating a filling step and a tension anchoring step. [44] Referring to FIGS. 7 to 9, an anchor construction method 200 in accordance with an exemplary embodiment of the present invention includes a hole piercing step.

[45] In the hole piercing step, an auger screw having a small diameter is used to pierce the ground to form a hole h. The piercing depth should be set to pass a slope surface s.

[46] After the hole piercing step, an insertion step is performed. In the insertion step, an anchor 100 constituted as described above is coupled to tension members w and then inserted into a lower part of the hole h. At this time, conductive wires electrically connected to a power supply are also inserted. The conductive wires are disposed adjacent to metal mixture m through through-holes 39 of an anchor extension body 30.

[47] After the anchor 100 is inserted, an extension step is performed. In the extension step, a thermite reaction is caused in the metal mixture m. That is, electric power is applied to the power supply to generate arc at end parts of the conductive wires adjacent to the metal mixture m. Energy generated by the arc is transmitted to the metal mixture m, and the metal mixture m starts the thermite reaction. Once the thermite reaction starts, continuous thermite reactions are maintained. Generation of the thermite reaction causes expansion force to outwardly widen extensions 32 of an anchor extension body 30, thereby pressing against an inner periphery of the hole h. Eventually, a diameter of the hole h is enlarged. In this process, projection pieces 38 formed at the extensions 32 of the anchor extension body 30 in an acute angle pierce the inner periphery of the hole h to be inserted thereinto.

[48] When the hole h expands as described above, a grouting material g such as cement paste is filled into the hole h to perform a filling step. When the grouting material is cured, the tension members m are tensed by a predetermined load to anchor the grouting material at an anchor head 60, thereby completing a tension anchoring step. Then, the tension members m may be removed.

[49] When the anchor 100 is constructed through the method as described above, since a portion of the hole h, at which the anchor 100 is disposed, has a larger volume than the other parts, the grouting material is cured to form a spherical structure. In addition, the anchor extension body 30 pierces the ground to increase anchor force between the anchor 100 and the ground. Therefore, when the anchor 100 in accordance with the present invention is constructed, the slope can be very stably supported in comparison with the conventional anchor construction method to prevent the slopes from collapsing or sliding. Reference numeral b designates an earth-blocking wall.

[50] FIG. 10 is a schematic exploded perspective view of an anchor in accordance with another exemplary embodiment of the present invention, FIG. 11 is a schematic perspective view of the anchor of FIG. 10 after assembly, FIG. 12 is a schematic cross- sectional view taken along line XII-XII of FIG. 11, and FIG. 13 is a cross-sectional view of a raised state of an extension cap of FIG. 12. [51] Referring to FIGS. 10 to 13, an anchor 100' in accordance with another exemplary embodiment of the present invention includes an anchor main body 10, an anchor extension body 30, and an extension means. Since the anchor main body 10 and the anchor extension body 30 are equal or similar to the embodiment described above, the extension means will be mainly described below.

[52] The extension means in accordance with another exemplary embodiment of the present invention includes an extension cap 50, a metal mixture m for causing a thermite reaction, and an energy transmission device 41.

[53] The extension cap 50 is disposed at a lower part of the anchor extension body 30.

The extension cap 50 having a hollow shape surrounds an inner member 11 and tension members w, and is inserted into the anchor main body 10 to be movable in a longitudinal direction of the anchor main body 10. The extension cap 50 includes an insertion part 51 and a slant extension part 52. The insertion part 51 forms an upper part of the extension cap 50, and has a diameter smaller than that of the anchor extension body 30. The slant extension part 52 extends downward from the insertion part 51 to be widened outward from the insertion part 51. Therefore, the diameter of the slant extension part 52 is increased as goes toward its lower part, and is larger than that of the insertion part 51, except the uppermost part of the slant extension part 52. Meanwhile, a plurality of through-holes 59 are formed at an upper surface of the extension cap 50. The tension members w pass through the through-holes 59.

[54] The metal mixture m is disposed under the extension cap 50, but in this exemplary embodiment, mounted on both sides of the inner member 11 of the anchor main body 10. The powder- type metal mixture m is contained in, for example, fabric pockets to be mounted on the anchor main body 10.

[55] The energy transmission device 41 supplies energy ΔE for inducing the thermite reaction to the metal mixture m.

[56] In the anchor 100' constituted as described above, when the thermite reaction is caused in the metal mixture m, expansion force is generated, and the extension cap 50, which is movably installed, raises along the anchor main body 10 to be inserted into the anchor extension body 30. While the insertion part 51 of the extension cap 50 has a diameter smaller than that of the extensions 32, since the slant extension part 52 of the extension cap 50 has a diameter larger than that of the extensions 32 of the anchor extension body 30, when the extension cap 50 is inserted into the anchor extension body 30, the extensions 32 of the anchor extension body 30 is bent outward to be widened as shown in FIG. 13. In addition, the outwardly bent extensions 32 press against the inner periphery of the hole h to enlarge the hole h. Therefore, similar to the exemplary embodiment described above, it is possible to increase anchor force between the anchor and the ground and form a spherical structure having a large diameter at a deep end of the hole, thereby stably reinforcing the slope.

[57] While few exemplary embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes may be made to these embodiments without departing from the spirit and scope of the invention as defined by the appended claims and their equivalents.

Claims

[1] An anchor, which comprises an anchor main body coupled to a plurality of tension members longitudinally disposed in one direction at its one end to be buried in a hole, comprising: an anchor extension body including a hollow-shaped case coupled to the anchor main body to surround an outer periphery of the anchor main body, and a plurality of extensions disposed in a circumferential direction of the case to be spaced apart from each other, each of which extends from an end of the case in a longitudinal direction of the anchor main body; and an extension means for widening ends of the extensions of the anchor extension body toward an inner periphery of the hole such that the extensions press against the inner periphery of the hole to enlarge the hole.

[2] The anchor according to claim 1, wherein the extension means comprises: a metal mixture disposed between the anchor main body and the anchor extension body, and formed of metal oxide and metal powder to cause a thermite reaction; and an energy transmission device for transmitting energy to the metal mixture to induce the thermite reaction in the metal mixture.

[3] The anchor according to claim 1, wherein the extension means comprises: an extension cap disposed at a lower part of the anchor extension body, movably inserted into the anchor main body along a longitudinal direction of the anchor main body, and having an insertion part having a hollow shape, with a diameter smaller than that of the anchor extension body and a slant extension part widening outward from the insertion part to have a diameter larger than that of the anchor extension body; a metal mixture disposed under the extension cap, and formed of metal oxide and metal powder to cause a thermite reaction; and an energy transmission device for transmitting energy to the metal mixture to induce the thermite reaction in the metal mixture.

[4] The anchor according to claim 2 or 3, wherein the energy transmission device comprises a power supply, and two conductive wires electrically connected to a positive terminal and a negative terminal of the power supply and having lower ends spaced a predetermined distance from each other to be disposed adjacent to the metal mixture, wherein, when electric power is applied to the power supply, energy by arc generated between the lower ends of the two conductive wires is transmitted to the metal mixture to cause the thermite reaction.

[5] The anchor according to claim 2 or 3, wherein the energy transmission device comprises a power supply, two conductive wires electrically connected to a positive terminal and a negative terminal of the power supply and having lower ends spaced a predetermined distance from each other to be disposed adjacent to the metal mixture, and a heat generating resistor connecting the lower ends of the two conductive wires to each other, wherein, when electric power is applied to the power supply, energy generated by the heat generating resistor is transmitted to the metal mixture to cause the thermite reaction.

[6] The anchor according to claim 2 or 3, wherein the metal powder comprises aluminum, and the metal oxide comprises copper oxide.

[7] The anchor according to claim 2 or 3, wherein the anchor extension body further comprises connection parts disposed between the extensions to connect the adjacent extensions, wherein, when the thermite reaction is caused by the metal mixture, the connection parts are broken to separate the extensions of the anchor extension body from each other.

[8] The anchor according to claim 2 or 3, wherein the extensions of the anchor extension body have projection piece projecting in a direction intersecting a longitudinal direction of the anchor extension body such that the extensions of the anchor extension body pierce the inner periphery of the hole to be inserted into the ground.

[9] The anchor according to claim 8, wherein the projection piece comprises a vertical part formed in a direction perpendicular to the longitudinal direction of the anchor extension body, and an inclination part disposed to form an acute angle with respect to the vertical part.