KR20120119463A - Anchor head device - Google Patents

Abstract

PURPOSE: A ground anchor is provided to ensure simple and quick installation and thereby prevent the loss of a tensile force when installation in soft ground. CONSTITUTION: A ground anchor comprises an axial rotation unit(21) extended in an axial direction and a variable expansion unit which expands or contracts in the lateral direction perpendicular to the axial direction according to the axial rotation of the axial rotation unit. The axial rotation unit comprises a screw rod which is extended in the axial direction and rotated along with the rotation of the axial rotation unit, an axial rotating body(23) which is coupled with the screw rod and a strand on respective end thereof, and an axial fixture in which the axial rotating body is supported and rotated.

Description

Ground Anchor {Anchor head device}

The present invention relates to an acupressure friction type (composite type) removable ground anchor which prevents the tension member and the loss of tensile force generated during anchor construction in the soft ground, and can be installed easily and quickly. It relates to a ground anchor that is expanded in accordance with the rotation of one direction of the ground to settle in the ground.

The present invention also relates to a ground anchor that is expandable and retractable as the strand is screwed to the strand that forms the tension member free field, as the strand is rotated in one direction and the other.

Furthermore, the present invention relates to a ground anchor that allows the anchor body and the strand to be separated in accordance with rotation of the other axis of the strand.

In general, the strand is a wire member manufactured by twisting a plurality of strands of steel wire (or "wire"), and is widely known under the name of Prestressed Concrete (PC) or Prestressed (PS) strand.

In particular, the PC or PS strand is used in the reinforcement work such as ground reinforcement, retaining wall repair, installation, etc. necessary for reinforcing natural slopes and artificial slopes, construction of underground structures and tunnels, adjacent to building trenches, railways and roads, It is used as a component that constitutes a tension member attachment field and a tension member free field of an anchor, which is a reinforcing structure to prevent collapse of the excavation ground.

Figure 8 is to connect the high-strength strand (w) in the longitudinal direction in order to fix the civil engineering or building structure on the ground and to introduce a high tension force to the strand, so that it is possible to apply a constraining force or a transverse load in the transverse or vertical direction to the structure As a reinforcing structure, the state in which the ground anchor is formed in the excavation ground is shown.

The ground anchor shown in FIG. 8 drills the ground to form an anchor hole 250 (groove ball), and after inserting the anchor body A and the tension part B including the stranded wire into the anchor hole, It is formed by performing the process of fixing the anchor head (C) exposed to the ground after the grout construction. On the other hand, in the removable ground anchor, after the formation of the reinforcing structure, the strand wire w used as the tension member is removed.

Here, the anchor body (A) comprises a tip end portion of the strand (w) and an anchor tip head portion 240 (commonly called an anchor) provided at the tip of the strand (w); As it is fixed in the ground through the grout or anchor construction, it forms a "tensile material attachment site" or "anchor anchorage site" which is a fixing structure for anchoring the anchor in the ground; The tension portion B composed of a plurality of strands w extending from the anchor body to the ground forms a "tension free field" or "anchor free field". In addition, the anchor head (C) is supported by the strand (w) in the state of maintaining the tensile force by using the pedestal 210, the pressure plate 220, the anchoring hole 230, the anchor body (A) and the tension portion (B) serves to fix (maintain) to the ground.

On the other hand, the anchor tip head portion 240 is attached to the tip of the strand (w) to expand the tip diameter, as a component for fixing the anchor body in the ground, generally in a cylindrical shape of a diameter larger than the diameter of the strand Is formed.

By the way, the anchor method conventionally used in this field, by simply injecting the grout material into the anchor hole 250 formed in the anchor rock, etc. to form a fixing grout, the tensile load under the frictional resistance with the ground or rock As it takes the form of supporting the soft ground or rock, the number, spacing, and tensile time of the inner body are controlled to prevent the loss of tensile force and tensile force that occur when the anchor is constructed in the soft ground. However, there was a difficulty in obtaining a result with a predetermined goal.

On the other hand, ground anchors conventionally used in this field are known to be anchors of acupressure friction type (composite type) supported by the grout and the ground surface frictional force of the ground, and the pressure resistance between the grout and the ground by expansion-type grounding; Also known are removable anchors (or "temporary anchors") capable of removing strands and the like. In addition, in the anchor of acupressure friction type (composite type), the anchor tip head portion 240 structure is adopted to improve the fixing performance with the ground by inserting it into the ground and expanding the diameter.

Currently, research is being conducted to improve the friction and tensile strength in the soft ground by improving the structure and function of the acupressure friction type (composite type) and the removable anchor.

The present invention has been made in view of the above circumstances, and in order to prevent the loss of tensile force and tensile force generated during anchor construction in soft ground, a simple and quick installation of acupressure friction type (composite type) removable ground anchors It is an object of the present invention to provide a ground anchor which is inserted into the ground and then expanded in accordance with the axial rotation of the strand to settle in the ground.

In addition, an object of the present invention is to provide a ground anchor that is expandable and retractable in accordance with the rotation of one direction and the other direction of the strand as screwed to the strand to form the tension member free field.

In addition, it is an object of the present invention to provide a ground anchor that allows the strand to be separated in the state in which the anchor tip head portion is expanded in accordance with the rotation of the other axis of the strand.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not intended to limit the invention to the precise form disclosed. There will be.

In order to achieve the above object, the present invention, the axial rotation portion extending in the axial direction; It provides a ground anchor comprising a variable expansion portion that expands or contracts in the lateral direction orthogonal to the axial direction in accordance with one or another axial rotation of the axis of rotation.

In addition, the present invention, the shaft rotation portion, the screw rod which extends in the axial direction and rotates in conjunction with the rotation of the shaft rotation portion; An axial rotating body in which the screw rod is coupled to the other side facing the axial direction and the strand is screwed to one side facing the other side; It provides a ground anchor, characterized in that the shaft rotating body includes a shaft fixing body which is supported rotatably.

In addition, the present invention, the variable expansion portion, the axial moving body that moves back and forth along the axial direction on the screw rod; And a linking body hingedly connected to the axial movable body and the axial fixing body and simultaneously contracting and expanding in the lateral direction as the axial movable body moves forward and backward. do.

In addition, the present invention provides a ground anchor, characterized in that the projection is coupled to the axial moving body, the screw rod is screwed to the extension hole formed with the thread of the projection.

In addition, the present invention, the extension portion is formed by twisting a plurality of element wires; It provides a ground anchor comprising a thread formed on the end of the extension.

According to the configuration as described above, while providing a ground friction-type (ground type) removable ground anchor that can be easily and quickly installed in the soft ground, and after being inserted into the ground, the ground anchor is expanded in accordance with the axial rotation of the strand It is possible to settle underground.

In addition, it provides a ground anchor that can be screwed to the strand to form the tension member free field, and at the same time can expand and contract according to the rotation of the axial line in one direction and the other direction.

In addition, in accordance with the rotation of the other axis of the strand, the strand can be separated in the expanded state of the tip head portion.

1A is a perspective view showing a stranded wire according to Embodiment 1 of the present invention;
Figure 1b is a view showing a state in which the strand and anchor tip head portion coupled according to the first embodiment of the present invention,
2A is a perspective view illustrating a stranded wire according to a modification of Embodiment 1 of the present invention;
Figure 2b is a view showing a state in which the strand and anchor tip head portion coupled according to a modification of Embodiment 1 of the present invention,
Figure 3a is a perspective view showing a strand in accordance with a second embodiment of the present invention,
Figure 3b is a view showing a state in which the strand and anchor tip head portion coupled according to the second embodiment of the present invention,
4A is a perspective view showing a strand in accordance with a modification of Embodiment 2 of the present invention;
4B is a view illustrating a state in which the strand and the anchor tip head are coupled according to the modification of Embodiment 2 of the present invention;
5 is a perspective view showing the configuration of the anchor tip head portion according to the present invention used in combination with the strand according to the present invention,
6a to 6c is an operation state diagram of the anchor tip head portion according to the present invention,
7A is a view showing a state in which the ground anchor in the initial contracted state shown in FIG. 6A is injected into the ground through the anchor hole;
7B is a view showing an expanded state of the anchor tip head of the ground anchor injected into the ground;
8 is a schematic cross-sectional view showing a state in which the reinforcing structure is formed by the ground anchor in the excavation ground.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. On the other hand, the present invention can be implemented in a number of different forms, the following description should be understood as an embodiment.

[Example]

(Composition of stranded wire)

1A is a perspective view of a stranded wire according to a first embodiment of the present invention, in which the stranded wire 10a according to the present invention includes a plurality of peripheral strands 11, 12, and 13 in which a steel wire is generally used. An extension part 15 formed by being twisted to the center; It consists of a thread 16 formed on this extension 15.

Here, the element wire may be composed of a string manufactured using a material of various materials other than steel, and may be formed by combining a single string or a plurality of strings. In the present specification, the meaning of the small wire means that the diameter of the string is smaller than the diameter of the cross section of the extension part 15, and the steel wire or the string is hereinafter referred to as the "small wire".

In the strand 10a according to FIG. 1A, a thread 16 is formed at the end 15a of the extension 15, and the strand may be screwed to the coupling member 20 via the thread.

Here, the coupling member 20, for example, may be composed of an anchor tip head portion 240 or a fixing unit 230; As shown in FIG. 1B, when the coupling member 20 is implemented as the anchor tip head 240, the coupling member 20 includes the nasan acid 16 formed at the end portion 15a of the extension portion 15. An insertion hole 25 into which an end portion of the extension portion is inserted is formed for the coupling of the insertion hole, while a receiving thread 26 having a shape corresponding to the screw thread 16 is formed on the surface of the insertion hole.

Therefore, by rotating the strand wire 10a or the coupling member 20 in a state where the end portion and the insertion port are in contact with each other, the strand wire 10a and the coupling member 20 can be engaged or released.

Meanwhile, in FIG. 1, the thread 16 shows a state formed at the end 15a of the extension part 15, but the thread 16 is formed or extended over the entire position on the extension part 15 of the strand. It may be selectively formed in a plurality of locations spaced apart on the part 15. Preferably, it may be formed at both ends of the extension 15.

In one example, as shown in Fig. 2A, the thread 16 is formed at one end 15a of the extension part 15, and at a position (preferably the other end) spaced apart from the end by a predetermined distance h. By forming another thread 16a, the stranded wire 10a 'in which the two threads 16 and 16a were formed on the extension part 15 of the stranded wire can be provided.

Here, the predetermined distance h, when considering the case applied to the ground anchor installed in the ground reinforcement work site, to form a distance h approximately equal to the distance between the anchor tip head 240 inserted in the ground between the anchorage 230 It is preferable.

At this time, the coupling member 20 screwed to the end portion 15a of the extension portion 15 may be composed of an anchor tip head portion 240, the screw thread on another thread (16a) of the extension portion 15 Coupling member 20 ′ to be coupled may be configured as anchorage 230.

Thus, as shown in Fig. 2B, the one end 15a is screwed to the engaging member 20, which is embodied as the anchor tip head 240; The other end may be screwed to the coupling member 20 'implemented as anchorage 230

3A is a perspective view of a stranded wire according to a second embodiment of the present invention. In the stranded wire 10b according to the second embodiment, a plurality of peripheral wires 11, 12, and 13 in which steel wires are generally used are formed in the center element wire 14. Extension portion 15 is formed by twisting the center; An integral part 17 on which the plurality of wires are integrated on the extension part 15; It comprises a screw thread 16 formed on this integral part.

Here, the integral portion 17 is heated by melting a predetermined portion of the general strand (w), and then solidified, so that the plurality of peripheral element wires (11, 12, 13) and the center element wire 14 is melted and integrated. , Is formed. The reason for forming such an integral part is that in the ordinary strand, when the ends are exposed by cutting, the individual wires 11 to 13 are spaced apart from each other, even if the threads are formed on the outer surface of the end 15a. This is to solve the problem that the thread does not fit well (i.e. the thread is not constant) formed on the member.

On the other hand, in the strand 10b according to Fig. 3A, an integral part 17 is formed at the end 15a of the extension part 15, and a thread 16 is formed on the integral part; The strand wire 110b may be screwed to the coupling member 20 through the thread.

Here, the coupling member 20, for example, may be composed of an anchor tip head portion 240 or a fixing member 230, as shown in Figure 3b, the coupling member 20 as the anchor tip head portion 240 Is implemented, the coupling member 20 is formed with an insertion hole 25 into which the end of the extension is inserted for engagement with the nasan acid 16 formed at the end 15a of the extension 15. A receiving thread 26 of a shape corresponding to the screw thread 16 is formed on the surface of the insertion hole.

On the other hand, the integral part 17 can be formed in a plurality of spaced apart at various locations on the extension 15, as in the first embodiment, a plurality of threads formed on the integral part 17 is also formed Can be. Preferably, it may be formed at both ends of the extension 15.

In one example, as shown in FIG. 4A, the one end 15a of the extension part 15 is formed as an integral part 17 with the thread 16 and is spaced apart from the end by a predetermined distance h. Preferably, by further forming an integral part 17a provided with another thread 16a at the other end, the stranded wire 10b 'having two threads 16, 16a formed on the extension part 15 of the stranded wire. ) Can be provided.

Here, the predetermined distance h, when considering the case applied to the ground anchor installed in the ground reinforcement work site, to form a distance h approximately equal to the distance between the anchor tip head 240 inserted in the ground between the anchorage 230 It is preferable.

At this time, the coupling member 20 which is screwed to the thread of the integral portion 17 formed in the end portion 15a of the extension portion 15 may be composed of an anchor tip head portion 240, the extension portion 15 The coupling member 20 'which is screwed to the threaded portion 16a of the other integral part 17a of the may be composed of a fixing unit 230.

Thus, as shown in FIG. 4B, one end 15a of the strand 10b is screwed to the engaging member 20 implemented as the anchor tip head 240; The other end may be screwed to the coupling member 20 'implemented as anchorage 230

(Configuration of the anchor tip head portion 20 according to the present invention as the engaging member)

5 shows an anchor body composed of the strand 10 according to the present invention and the anchor tip head portion according to the present invention, which is a coupling member 20 screwed to the strand.

As shown in Fig. 5, the anchor tip head portion 20 according to the present invention comprises: an axis rotating portion 21 rotating on an axis X extending in the longitudinal direction; And a variable expansion portion 27 that expands or contracts in the lateral direction L orthogonal to the axial direction X in accordance with one or other axial rotations (axial rotation in the inward or outward direction in the drawing) of the axial rotation part. (FIG. 5 shows an expansion progress state).

On the other hand, the axial rotation part 21 is configured to further include a screw rod 22 extending in the axial direction X and rotating in conjunction with the rotation of the axial rotation part 21.

In addition, the shaft rotating portion 21, the screw rod 22 is coupled to one side surface 23a facing the axial direction, while the strand 10 is screwed to the other side surface 23b facing the one side surface A rotating body 23; This shaft rotating body 23 is comprised including the 1st support body 24: the shaft fixing body which is supported so that shaft rotation is possible. Here, an insertion hole 25 'is formed in the shaft rotating body 23 for screwing with the end portion of the strand 10 having the thread 16 formed thereon, and the thread 16 corresponds to the surface of the insertion hole. A receiving thread 26 'is formed.

Here, the axial rotating body 23 passes through the first support shaft 24 along the axial direction X, so that the other side surface 23b is exposed in front of the first support shaft 24, and the exposed other The screw rod 22 is coupled to the side 23b.

Accordingly, when the strand 10 is screwed into the insertion hole 25 'on one side 23a of the shaft rotating body 23, the screw rod 22, the shaft rotating body 23 and the first support ( 24) and the strand extends in a straight line on the axial direction X.

The variable expansion part 27 may include: a second support body 28 (an axial moving body) which is screwed to the screw rod 22 and moves forward and backward along the axial direction X in accordance with rotation of one and the other directions of the screw rod; A link that is hinged and interconnected in multiple stages between the second support 28 and the first support 24, and contracts and expands in the lateral direction L as the second support 28 moves forward and backward on the X axis. It comprises a sieve 29.

Here, the link body 29, the one end is hinged to the first support 24, the other end is first and second links (29a, b) extending in the lateral direction from the first support (24) (Rear link); Third and fourth links (29c, d: rear links) having one end hinged to the second support 28 and the other end extending laterally from the second support 28; And first and second connection links 29e and f that interconnect the other ends of the first and third links 29a and c and the other ends of the second to fourth links 29b and d, respectively. It is configured by. Meanwhile, as the coupling between the links 29a to d is performed by using the coupling pins 29p, the respective links are capable of multi-joint pivotal movement with respect to the first and second supports 24 and 28. .

In addition, the threaded rod (22) extending from the other side (23b) of the first support 28 is in communication with the other side through the one side of the second support (28); On this other side, the projection tip 28a of the same shape as the anchor tip head part 240 of a general shape is formed, for example by joining by welding. In addition, the protruding portion 28a is formed with an extension hole 28b in which a screw thread corresponding to the screw thread of the screw rod 22 is formed.

Therefore, the threaded rod 22 extending forward from the one side surface of the shaft rotating body 23 through the second support 28 is formed integrally with the second support 28 and protrudes forward. It is screwed to the extension hole 28b of 28a, and it moves along an extension hole. On the other hand, it is preferable that the length a of the protruding portion 28a and the extension hole 28b is longer than the length in consideration of the length of the screw rod 22. Furthermore, the diameter of the protrusion 28a is preferably formed to a diameter such that the link body 29 in the contracted state can be concealed by the diameter of the protrusion 28a when viewed from the front.

Hereinafter, the operation of the anchor tip head portion 20 according to the present invention with reference to the drawings.

First, in the initial state before the installation of the ground anchor, the strand 10 is axially rotated in one direction (inward direction in the drawing) with respect to the axial rotor 23 of the anchor tip head portion 20 via the thread of the end. It is screwed into the insertion port 25 of the axial rotation body 23. At this time, the worker engages the screw in a state in which the shaft rotator 23 is gripped and fixed to prevent the shaft rotator 23 from rotating along with the strand 10 with respect to the first support 24. Do this.

On the other hand, by rotating the shaft rotating body 23 in the other direction (outside direction in the drawing) in the state where the strand is fixed, the shaft rotating body 23 and the strand 10 may be screwed together.

In addition, the variable expansion part 27 of the said anchor tip head part 20 maintains a storage state, as shown to FIG. 6A. In the stored state, the anchor tip head portion 20 extends in the longitudinal direction on the X axis, at which the cross-sectional diameter or height b1 along the lateral direction L is projected so that only the projection 28a can be seen from the front. It is formed smaller than the diameter of 28a.

Specifically, the first and second links 29a and b are brought into contact with each other by one end thereof pivoting with respect to the first support 24 and approaching on the X axis, respectively; The third and fourth links 29c and d are brought into contact with each other by one end thereof pivoting with respect to the second support 28 and approaching on the X axis, respectively; The first and second connecting links 29e and f are pivoted about the first and third links and the second and fourth links, which are positioned to face each other through one side and the other end thereof, to approach the X axis, respectively. You will come across each other. At this time, the first and second connecting links 29e, f are located parallel to each other with respect to the axial direction X.

Further, the tip of the screw rod 22 screwed to the extension hole 28b of the protruding portion is located near the right end of the extension hole (the inlet side position of the extension hole).

Here, the anchor tip head portion 20 in the initial state is injected into the ground through the anchor hole 250 in accordance with the anchor construction. The anchor tip head portion 20 injected into the ground is variable as shown in FIG. 6B as the stranded wire 10 screwed with respect to the shaft rotating body 23 is axially rotated in one direction (inward direction in the drawing). The expansion portion 27 extends in the lateral direction L orthogonal to the axial direction X.

 In this expanded traveling state, the cross-sectional diameter or height b2 along the lateral direction L of the anchor tip head portion 20 extends larger than the cross-sectional diameter of the protruding portion 28a.

Specifically, in accordance with the axial rotation of the strand 10, the first support 24 and the screw rod 22 coupled to the first support 24 are axially rotated together with each other; The second support body 28 (axially movable body) screwed to the screw rod 22 travels backward (right side in the drawing) by performing the first support member 24 on the screw rod 22.

Accordingly, the first and second links 29a and b of the variable expansion part 27 are pivoted rearward with respect to the first support 24 so that one end thereof is spaced apart from each other in the lateral direction from the X axis. ; One end of the third and fourth links 29c and d pivots forward with respect to the second support 28 so as to be spaced apart from each other in the lateral direction from the X axis; The first and second connecting links 29e and f are pivotally spaced apart from the X axis, respectively, with respect to the first and third links and the second and fourth links, which are located opposite each other through one side and the other end thereof. At this time, the first and second connection links 29e and f are spaced in parallel with each other in the axial direction x, and the first and third links and the second and fourth links are predetermined with respect to the lateral direction L. They have an symmetrical shape at an angle.

Further, the tip of the screw rod 22 screwed to the extension hole 28b of the projection 28a is advanced forward in the extension hole (as the retraction of the projection 28a toward the rear side) extends. It is located in a predetermined length inward position from the inlet end of the ball.

Here, as the anchor tip head portion 20 in the extended traveling state is further axially rotated in one direction (inward direction in the drawing), the stranded wire 10 screwed with respect to the axial rotation body 23, as shown in FIG. 6C. Similarly, the variable expansion part 27 is extended in the lateral direction L orthogonal to the axial direction X, and the link body 29 of the variable expansion part 27 becomes parallel with the lateral direction L. As shown in FIG. In this expanded state, the cross-sectional diameter or height b3 along the lateral direction L of the anchor tip head portion 20 is larger than the cross-sectional diameter of the protruding portion 28a. In other words, the relationship is b3> b2> b1.

Specifically, in accordance with the continuous axial rotation of the strand 10, the first support 24 and the screw rod 22 coupled to the first support 24 rotate together with each other; The second support body 28 (axially movable body) screwed with the screw rod 22 performs the first support member 24 on the screw rod 22 further to the rear side (right side in the drawing), and then In contact with the support 24.

Accordingly, the first and second links 29a and b of the variable expansion portion 27 have one end portion further pivoted to the rear side with respect to the first support 24 so that they are orthogonal to the axial direction X, respectively. Parallel to L; The third and fourth links 29c, d have their one end pivoted forward with respect to the second support 28 and are in parallel with the lateral direction L, respectively; The first and second connecting links 29e and f are pivoted with respect to the first and third links and the second and fourth links, which are located opposite each other through one side and the other end thereof, and are spaced apart from the X axis, respectively. Parallel to each other.

On the other hand, the tip of the threaded rod 22 screwed to the extension hole 28b of the projection 28a is further advanced forward in the extension hole 18b (as the retraction of the projection 28a toward the rear side). It is located in the innermost position of the extension hole.

(Construction method of ground anchor)

The ground anchor including the strand and anchor tip head portion 20 according to the present invention comprises: drilling an anchor hole (250: grout ball) in the ground; Injecting the anchor tip head portion 20 into the anchor hole together with the strand; Performing a grouting construction by milk-injecting grout material; It is installed underground through the process of fixing the exposed anchor head. Subsequently, after the predetermined period has elapsed, the anchor head fixing structure is released, the strand wire 20 is pivoted in the opposite direction to the one direction, separated from the anchor tip head portion 20, and withdrawn, and thus ground anchor construction is performed. You are done.

Here, FIG. 7A is a view showing a state in which the ground anchor composed of the anchor tip head portion 20 and the strand 10 in the initial state shown in FIG. 6A is injected into the ground through the anchor hole 250. As the end diameter or height b1 of the portion 20 is smaller than the protruding portion 28a, the anchor tip head portion 20 is easily injected into the anchor hole 250. Moreover, in the underground, the variable expansion part 27 of the anchor tip head part 20 maintains the contracted state.

On the other hand, by rotating the strand in one direction in the state of Figure 7a, to expand the variable expansion portion 27 of the strand.

7B is a view illustrating a state in which the anchor tip head portion 20 injected into the ground is fixed in the ground by expanding in accordance with the axial rotation of the strand 10, and the anchor tip head portion in the lateral direction orthogonal to the axial direction X. The variable expansion part 27 of 20 is shown in the fully extended state.

In this state, the end diameter or the height b3 is larger than the protruding portion 28a, and the fixability with the ground is improved.

On the other hand, as the axial rotation of the strand 10 in the other direction in the state of Figure 7b, the screw coupling of the strand 10 and the anchor head portion 20 is released, after the strand 10 is drawn out, The anchor tip head portion 20 in which the variable expansion portion is expanded is located.

10-strand, 20-tip head,
21-shaft rotation, 22-screw rod,
23-shaft rotator, 28-second support,
29-link type.

Claims (5)

An axial rotation part extending in the axial direction;
And a variable expansion part configured to expand or contract in a lateral direction orthogonal to the axial direction according to one or other axial rotations of the axial rotation part. The method of claim 1, wherein the shaft rotating portion,
A screw rod extending in the axial direction and rotating in association with the rotation of the axial rotation unit;
An axial rotating body in which the screw rod is coupled to the other side facing the axial direction and the strand is screwed to one side facing the other side;
And a shaft fixing member on which the shaft rotating body is rotatably supported axially. The method of claim 2, wherein the variable expansion unit,
An axial moving body moving forward and backward along the axial direction on the screw rod;
And a linking body hinged to the axial movable body and the axial fixing body and connected to each other and simultaneously contracting and expanding in the lateral direction as the axial movable body moves forward and backward. The method of claim 3,
The projection is coupled to the axial moving body,
The ground anchor, characterized in that the screw rod is screwed into the extension hole formed with the thread of the protrusion. The method of claim 2,
An extension part formed by twisting a plurality of element wires; And a thread formed on an end of said extension.

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