EP3135821B1

EP3135821B1 - Structure of permanent anchor

Info

Publication number: EP3135821B1
Application number: EP16181767.1A
Authority: EP
Inventors: Kyung Hoe Cha
Original assignee: Wharang Foundation Co Ltd
Current assignee: Wharang Foundation Co Ltd
Priority date: 2015-08-27
Filing date: 2016-07-28
Publication date: 2018-03-07
Anticipated expiration: 2036-07-28
Also published as: WO2017034152A1; EP3135821A1; TR201807752T4; CN106498944A; KR101605028B1

Description

BACKGROUND

Field

The present disclosure relates to a permanent anchor used for suppression of a collapse of cut slopes in a rock or ground cutting area or suppression of a collapse of excavation walls during engineering works and more particularly, to a leading end anchor for permanent anchoring in which anchor wings of the leading end anchor for performing a permanent anchoring method are configured to be expanded and unfolded by a grout injection pressure and grout is compactly filled around the leading end anchor and in an anchor hole due to a continuous discharge of grout after the expansion and unfolding of the anchor wings, so that the anchorage of the leading end anchor can be further improved and high-quality reinforcement work can be carried out without a weakness of a anchoring part caused by cracks.

Description of the Related Art

In general, permanent anchors have been used in a soil sheating work for suppression of a collapse of cut slopes in a rock or ground cutting area, stabilization of slopes, suppression of landslides, suppression of damage to a large-scale structure, such as a building or dam, caused by underground water, suppression of damage to an underground structure, and suppression of a collapse of excavation walls during an engineering work for building a basement of a large-scale building. Further, the permanent anchors have been installed to suppress movements or twists of a structure during construction of a building, a large-scale steel tower or a revetment in an earthquake area, and assist pressing during construction for a reaction of a cantilever and during a submergence of a caisson for underwater construction.
According to the permanent anchoring method, typically, an anchor hole 100 is perforated in a rock or ground likely to collapse with a drilling machine and a grout hose, a plurality of tension members 110, and a leading end anchor 130 are prepared as one unit and inserted through the anchor hole 100 as illustrated in FIG. 1. Then, grout is injected through the grout hose 120 inserted into the anchor hole 100. If the injected grout is cured with the leading end anchor 130 after a certain period of time, a pressing means is installed at the other end of the tension members 110 to fasten an anchoring device 140. Then, the tension members 110 within a steel strand are tensioned using a separate hydraulic device or the like to stabilize a target structure.
Such a conventional permanent anchor supports a tensile force from a surface due to a ground pressure of grout or a ground friction force. In the permanent anchoring method, an anchor includes an anchor body anchoring part configured to transfer a tensile force to the ground with the stress required, a free tension part configured to transfer a tensile force caused by the stress of the anchor body exhibited in an anchor head part, and the anchor head part configured to apply the stress required to a structure. Herein, the anchor body anchoring part is determined by a resistance between the ground and grout and between the grout and tension members.
Further, recently, there has been suggested a stronger permanent anchor configured to resist a tensile stress, a shear stress, and a bending moment through pre-anchoring of an anchor head part before grout is injected and hardened. Such a permanent anchor with an improved structure is as disclosed in Korean Patents Laid-open Publication No. 10-2009-0113436 and in KR101255811B1 .
Such a conventional permanent anchor provides the stiffness against drawing by a ground pressure of grout, and a plurality of cracks may be present around an anchor hole, into which the anchor is inserted, depending on the condition of the ground such as a weak ground, a slope, a rock, or the like. It is very difficult to check cracks within the perforated anchor hole from the outside. That is, when a tension member is inserted into the anchor hole to inject grout, the grout is filled in the anchor hole by an injection pressure. Therefore, when the grout is injected into the anchor hole, the grout may leak from the anchor hole through a plurality of cracks formed within the anchor hole. Thus, a grout filling rate within the anchor hole is decreased.
As such, a plurality of cracks within an anchor hole causes a remarkable decrease in grout filling rate. Thus, the ground cannot be reinforced in a substantial manner. Further, even if the cracks are formed within a part of the anchor hole, since the entire area within the anchor hole is one space, pores are generated within the grout filled in the entire area of the anchor hole. Thus, the ground cannot be reinforced in a substantial manner.
Therefore, it is very difficult and takes a considerable time to measure the strength of the grout filled in the anchor hole, which results in an increase in construction period together with an increase in extra expense such as construction expense. Further, if anchor construction such as reinforcement of a weak ground or a slope is carried out without checking the presence of pores caused by cracks within the grout filed in the anchor hole, such faulty construction may cause an increase in maintenance expense and a ground failure which may result in a big accident.
Further, as for the conventional permanent anchor, there is the inconvenience of selecting an anchor suitable for each ground condition and a weight is applied intensively from a leading end anchoring part to be inserted into the anchor hole, which causes structural instability. Thus, the anchor hole is perforated and the anchoring part to be inserted into the anchor hole is formed longer. Therefore, it takes a longer time to perforate the anchor hole deeply and the increase in length of the anchoring part causes an increase in installation cost.
Furthermore, as described above, cement milk grouting, resin, and a leading end anchor are used to anchor an inner inserted body, i.e., a resistance length, of the anchor within the anchor hole to the ground as a pre-operation for tensioning the permanent anchor. However, conventional grouting and resin require some curing time. Therefore, if a ground deformation is in progress or water is present within the anchor hole, tensioning cannot be performed well. Further, in case of a conventional leading end anchor, if tensioning is performed right before grout is injected, a leading end anchoring part to be pressed and anchored has a small resistance stress and thus may escape from the anchor hole during tensioning. Therefore, it is very difficult to obtain the tensile stress required.

SUMMARY

In view of the foregoing problems, an object to be achieved by the present disclosure is to provide an improved structure of a leading end anchor for permanent anchoring in which a steel wire fixing part for fixing and coupling tension wires and an anchoring head part configured to be expanded and unfolded by a grout injection pressure are included, and the anchoring head part is coupled to a lower end of the steel wire fixing part and includes a fluid operating by the grout injection pressure and a plurality of anchor wings configured to be expanded and unfolded by a pressure applied by the fluid. Thus, if grout is injected in a state where a leading end anchor is inserted into an anchor hole, the anchor wings are expanded and unfolded and then strongly stuck into an inner wall of the anchor hole so as to further improve the fixing force. Further, when the grout is discharged in a state where the anchor wings are anchored, the grout is discharged and filled around the anchoring head part and in the anchor hole. Thus, the anchoring force of the anchoring head part is greatly improved, so that a higher-quality permanent anchoring method can be realized.
The present disclosure to achieve the above object includes a steel wire fixing part to which tension members for permanent anchoring are fixed and an anchoring head part coupled to a lower side of the steel wire fixing part and fixed within an anchor hole, and the steel wire fixing part and the anchoring head part are anchored to a leading end within the anchor hole by grout. The anchoring head part includes: a supporting rod coupled to the steel wire fixing part; a pressurizing tube body fixed to a leading end of the supporting rod; a fluid to be inserted into the pressurizing tube body through an open bottom of the pressurizing tube body; and anchor wings radially hinge-coupled to a lower end of the supporting rod and brought into contact with a lower end of the fluid. The fluid is slid by a filling pressure of grout injected into the pressurizing tube body so as to expand and unfold the anchor wings to the outside.
According to the present disclosure, in case of embedding a leading end anchor into a perforated anchor hole, if the anchor hole has an insufficient depth, it is possible to immediately withdraw the leading end anchor without interference between an inner surface of the anchor hole and the leading end anchor. Thus, after a re-perforation operation is performed, it is possible to embed the leading end anchor again. Therefore, it is easy to correct an operation. While anchor wings are expanded and unfolded by a discharge pressure of grout, the leading end anchor in an embedded state is strongly stuck into an inner wall of the anchor hole. Therefore, the fixing force of the leading end anchor and the anchoring force caused by the grout can be greatly improved. Thus, a permanent anchor can efficiently perform reinforcement around the leading end anchor and pores or cracks are not generated in the grout at a leading end of the anchor hole. Therefore, high-quality construction can be carried out.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features and other advantages of the present disclosure will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which:

FIG. 1 is an overall schematic diagram of a conventional permanent anchoring method;
FIG. 2 is an overall perspective view of a leading end anchor according to the present disclosure;
FIG. 3 is an overall front view of the leading end anchor according to the present disclosure;
FIG. 4 is an exploded cross-sectional view of the leading end anchor according to the present disclosure;
FIG. 5 is a perspective view of a state where tension members are coupled and fixed to the leading end anchor according to the present disclosure;
FIG. 6 is a diagram illustrating a state where the leading end anchor according to the present disclosure together with the tension members are embedded in an anchor hole;
FIG. 7 is an enlarged view illustrating a process performed by the leading end anchor according to the present disclosure and also a cross-sectional view of a state where grout starts to be injected;
FIG. 8 is an enlarged view illustrating a process performed by the leading end anchor according to the present disclosure and also a cross-sectional view of a state where anchor wings are expanded by injection of the grout;
FIG. 9 is an enlarged view illustrating a process performed by the leading end anchor according to the present disclosure and also a cross-sectional view of a state where the grout is filled in an anchor hole by continuous injection of the grout;
FIG. 10 is a cross-sectional view of a state where the grout is filled in and around the leading end anchor according to the present disclosure; and
FIG. 11 is an overall diagram of a state where the leading end anchor according to the present disclosure is configured for used in bedrocks.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Terms and words used in the present specification and claims are not to be construed as a general or dictionary meaning, but are to be construed to meaning and concepts meeting the technical ideas of the present disclosure based on a principle that the inventors can appropriately define the concepts of terms in order to describe their own inventions in the best mode.
Hereinafter, the exemplary embodiments of the present disclosure will be described in detail with reference to the accompanying drawings.
FIG. 2 is an overall perspective view of a leading end anchor according to the present disclosure, FIG. 3 is an overall front view of the leading end anchor according to the present disclosure, and FIG. 4 is an exploded cross-sectional view of the leading end anchor according to the present disclosure.
As illustrated in the drawings, the leading end anchor according to the present disclosure includes a steel wire fixing part 10 configured to fix tension members 110 formed of cables and an anchoring head part 20 connected and coupled to a lower side of the steel wire fixing part 10. In a state where the steel wire fixing part 10 and the anchoring head part 20 together with the tension members 110 are embedded deeply into an inner leading end of an anchor hole 100, the anchoring head part 20 is anchored within the anchor hole 100 by cement milk grout injected into the anchor hole 100. Thus, reinforcement of a slope part can be carried out by tensioning of the tension members 110.
Herein, in the steel wire fixing part 10, guiding parts 12 and 12' including fixing grooves 11 and 11' formed in all directions are formed to be vertically spaced away from each other, a winding part 13 around which a single tension member 110 can be wrapped and bent is formed at a bottom surface of the lower guiding part 12', and a coupling hole 14 penetrating the winding part 13 is formed at a lateral surface of the winding part 13.
Further, the anchoring head part 20 includes a supporting rod 30 including a coupling piece 21 protruded and formed at a leading end, and a bottom-opened pressurizing tube body 40 fixed and formed on the supporting rod. A separate fluid 50 is inserted in the pressurizing tube body 40, and a plurality of anchor wings 60 and 60' coupled to a hinge-coupling part 31 of the supporting rod 30 are provided under the fluid 50.
Herein, the coupling piece 21 is protruded and formed at the leading end of the supporting rod 30. Thus, the coupling piece 21 is brought into close contact with the coupling hole 14 formed in the winding part 13 of the steel wire fixing part 10 so as to connect and couple the steel wire fixing part 10 and the anchoring head part 20 to each other with a separate fixing pin 22.
Further, the hinge-coupling part 31 radially protruded and formed at a lower end of the supporting rod 30 is hinge-coupled to each of the anchor wings 60 and 60'. Thus, the anchor wings 60 and 60' can be expanded and unfolded from the supporting rod 30 to the outside.
Furthermore, the pressurizing tube body 40 has a bottom-opened inner space. On a top surface of the pressurizing tube body 40, a pipe connection hole 42 is formed so as to communicate with the inner space. Thus, the pressurizing tube body 40 can be coupled to a separate grout injection pipe 41 through the pipe connection hole 42. On one side of the top surface of the pressurizing tube body 40, a circular cutting board 44 is formed as one body by a vertical cutting groove 43. A discharge groove part 45 is formed into a recessed groove on a lower side of an inner surface of the pressurizing tube body 40.
Also, the fluid 50 is closely inserted into the pressurizing tube body 40 and slides in an inner space of the fluid 50. The inner space of the pressurizing tube body 40 has a sealed structure after the fluid 50 is inserted. Thus, as the pressure within the inner space of the pressurizing tube body 40 is increased, the fluid 50 is pushed out.
Further, one side of each of the anchor wings 60 and 60' is slantly in contact with the fluid 50 and the other side of each of the anchor wings 60 and 60' includes a slope part 61. One or more sharp tip parts 62 and 62' are formed on outer surfaces of the anchor wings 60 and 60', respectively.
Accordingly, in a state where the anchoring head part 20 is coupled to the lower side of the steel wire fixing part 10 by the supporting rod 30, the pressurizing tube body 40, the fluid 50, and the anchor wings 60 and 60', the tension members 110 are united and fixed using the steel wire fixing part 10 as illustrated in FIG. 5, and then embedded into the anchor hole 100.
In this case, a method of uniting and fixing the tension members 110 with the steel wire fixing part 10 includes brining the respective tension members 110 into close contact with the fixing grooves 11 and 11' formed on the guiding parts 12 and 12' of the steel wire fixing part 10 and strongly pressurizing and fixing them at the same time using a separate metal band or the like. One of the tension members 110 is united and fixed as being bent in a "U"-shape along the winding part 13 under the tension member 110. Thus, the tension member 110 wrapping around the winding part 13 further improves the uniting and fixing force between the steel wire fixing part 10 and the tension members 110.
The leading end anchor in the above-described state is embedded into the anchor hole 100 previously perforated as illustrated in FIG. 6. The anchor hole 100 is perforated to have an inner diameter greater than an outer diameter of the leading end anchor including the tension members 110. Thus, the leading end anchor can be freely embedded without interference therebetween.
Further, while the leading end anchor is embedded, if the anchor hole 100 has an insufficient perforation depth, the leading end anchor is withdrawn again and the anchor hole 100 needs to be re-perforated. As for the conventional leading end anchor, during the above-described withdrawal process, interference with an inner wall of the anchor hole 100 severely occurs. Thus, it is very difficult to perform the withdrawal operation. Further, the conventional leading end anchor has a structure which cannot be withdrawn. Therefore, re-perforation or correction of the anchor hole 100 performed in the present disclosure cannot be performed rationally.
Thus, if the leading end anchor is embedded into an inner leading end of the anchor hole 100 by perforating the anchor hole 100, embedding and withdrawing the leading end anchor, and re-perforating the anchor hole 100 according to the present disclosure, grout is injected into the pressurizing tube body 40 through the grout injection pipe 41 connected to the pressurizing tube body 40 of the anchoring head part 20 as illustrated in FIG. 7.
Thus, as the grout is filled in the pressurizing tube body 40, the fluid 50 is pushed to the outside of the pressurizing tube body 40 by a pressure of the grout. While the fluid 50 is pushed toward the anchor wings 60 and 60', the anchor wings 60 and 60' slantly interfering with the fluid 50 are expanded and unfolded to the outside as illustrated in FIG. 8, so that the tip parts 62 and 62' of the anchor wings 60 and 60' penetrate into the anchor hole 100.
Thus, while the anchor wings 60 and 60' are unfolded by outward rotation, the slope parts 61 formed on the anchor wings 60 and 60' suppress the rotation as being brought into contact with the supporting rod 30. At the same time, the discharge groove part 45 formed on the inner surface of the pressurizing tube body 40 communicates with the inner space of the pressurizing tube body 40 due to discharge of the fluid 50, so that the grout inside the pressurizing tube body 40 is discharged to the outside of the pressurizing tube body 40 as illustrated in FIG. 9. The grout discharged as such is filled around the anchor wings 60 and 60' and filled deep into the leading end of the anchor hole 100.
Further, during the above-described process, if the grout is fully filled into the pressurizing tube body 40 and the inner leading end of the anchor hole 100 including the anchor wings 60 and 60', a pressure of the corresponding space is increased. Thus, the increased pressure is applied to the inside of the pressurizing tube body 40. Therefore, the pressure is also applied to the cutting board 44 of the pressurizing tube body 40, resulting in a cross-sectional fracture at the cutting groove 43. Thus, the cutting board 44 is separated or split to the outside of the pressurizing tube body 40 by a momentary fracture.
Therefore, after the cutting board 44 is split from the pressurizing tube body 40, a hole is naturally formed at an upper part of the pressurizing tube body 40 where the cutting board 44 was located. Thus, the grout inside the pressurizing tube body 40 is discharged toward the steel wire fixing part 10 and filled through the hole.
Accordingly, if the grout is compactly injected into the anchoring head part 20 and the grout is completely injected into the steel wire fixing part 10 and then, the injected grout is fully cured, the steel wire fixing part 10 and the anchoring head part 20 can be strongly anchored and fixed by the grout within the anchor hole 100 as illustrated in FIG. 10. The anchor wings 60 and 60' of the anchoring head part 20 are fixed by the grout while the anchor wings 60 and 60' penetrate the inner wall of the anchor hole 100 as being expanded to the outside. Therefore, even if a high tensile force is applied to the tension members 110, the anchorage stability is excellent in an anchoring section.
In the above-described leading end anchor according to the present disclosure, it is desirable to form a plurality of tip parts 62 and62' on the outer surfaces of the anchor wings 60 and 60' for soils. Meanwhile, as for bedrocks, toothed parts 63 and 63' are continuously formed on the outer surfaces of the anchor wings 60 and 60' as illustrated in FIG. 11, so that if the anchor wings 60 and 60' are expanded to the outside, the toothed parts 63 and 63' strongly interfere in and resist the inner surface of the anchor hole 100 formed of bedrocks so as to very effectively suppress a re-withdrawal from the anchoring head part 20.
Therefore, in case of correcting a perforation depth of the anchor hole 100, the leading end anchor of the present disclosure can be easily drawn from an embedded state and then can be embedded again. Further, while the anchor wings 60 and 60' are expanded and unfolded as being rotated in all directions by a grout injection pressure, the anchor wings 60 and 60' are fixed as being strongly stuck into the inner leading end of the anchor hole 100 formed of soils or bedrocks. Thus, the anchoring force of the leading end anchor can be further improved. The grout is cured while being compactly filled deep into the anchor hole 100 and around the anchoring head part 20 and in the steel wire fixing part 10. Thus, the anchoring force of the leading end anchor of the present disclosure can be further improved, and construction such as slope reinforcement using a permanent anchor can be carried out with a higher quality.

Claims

A structure of a permanent anchor comprising:
a steel wire fixing part (10) to which tension members (110) for permanent anchoring are fixed; and

an anchoring head part (20) coupled to a lower side of the steel wire fixing part (10) and fixed within an anchor hole,

wherein and the steel wire fixing part (10) and the anchoring head part (20) are anchored to a leading end within the anchor hole (100) by grout,

in the steel wire fixing part (10), upper and lower guiding parts (12) and (12') including fixing grooves (11) and (11') radially formed on outer peripheries are formed, a winding part (13) extended from the fixing grooves (11) and (11') is protruded downwardly from the lower guiding part (12') in order for the tension members (110) to be inserted and united through the fixing grooves (11) and (11'), a single tension member (110) is united as being bent via the winding part (13), and a coupling hole (14) is formed at a lower side of the winding part (13),

the anchoring head part (20) includes a pressurizing tube body (40), a fluid (50), and anchor wings (60,60'), and the fluid (50) is slid by a filling pressure of grout injected into the pressurizing tube body (40) so as to expand and unfold the anchor wings (60) and (60') to the outside,

the steel wire fixing part (10) and the anchoring head part (20) are connected and coupled by a supporting rod (30) including a coupling piece and a hinge-coupling part,

the supporting rod (30) and the steel wire fixing part (10) are connected by engaging a fixing pin into a coupling hole for the coupling piece of the supporting rod and the steel wire fixing part,

the anchor wings are hinge-coupled through the hinge-coupling part of the supporting rod,

the pressurizing tube body (40) is fixed to the supporting rod and the fluid (50) is located within the pressurizing tube body and thus slid as being fit in the supporting rod,

a discharge groove part (45) is formed on a lower side of an inner surface of the pressurizing tube body (40), so that if the fluid (50) is pushed out by grout injected into the pressurizing tube body (40), the discharge groove part (45) communicates with the inside of the pressurizing tube body (40) so as to discharge the grout inside the pressurizing tube body (40) to the outside through the discharge groove part (45),

on a top surface of the pressurizing tube body (40), a pipe connection hole (42) is formed to be screw-connected to a grout injection pipe (41) and a cutting board (44) is also formed by a cutting groove (43), and

when a pressure of the grout injected into the pressurizing tube body (40) is increased, the cutting grove (43) is fractured and the cutting board (44) is split and removed to the outside of the pressurizing tube body (40).
The structure of a permanent anchor according to claim 1, wherein one side of each of the anchor wings (60,60') is slantly in contact with the fluid (50) and the other side of each of the anchor wings (60,60') includes a slope part (61),
the anchor wings (60,60') are expanded and unfolded from the supporting rod (30) by outward rotation according to a movement of the fluid (50),
while the anchor wings (60,60') are expanded and unfolded, an angle of expansion and unfolding is restricted by interference between the slope parts (61a) and the supporting rod (30),
tip parts (62,62') configured to penetrate soils of the anchor hole (100) or toothed parts (63,63') configured to be engaged with and fixed to bedrocks of the anchor hole (100) are protruded and formed on outer surfaces of the anchor wings (60,60').