JPH0460014A - Ground anchor method - Google Patents

Abstract

PURPOSE:To uniform the tensile forces of cables and the loads to load-resisting bodies by engaging a set of anchor cable groups directly with a load-resisting body on the top end, and other cable groups to other load-resisting bodies through elastic bodies, respectively. CONSTITUTION:Twelve anchor cables 3, for example, to be inserted into an anchor hole 2 in the ground G are covered with a sheath tube 8, and four load- resisting bodies 9A-9D, for example, are installed thereto at fixed intervals. The cables 3 are divided into four sets of anchor cable groups 3A-3D as many as the load-resisting bodies 9, and the group 3A is directly engaged with the top end side load-resisting body 9A. Further, the groups 3B-3D are engaged with the load-resisting bodies 9B-9D through elastic bodies 16B-16D whose elastic deforming quantities are set to uniform the tensile forces, respectively, and each group 3A-3D is collectively strained. The elongation and tensile force of each cable 3 is uniformed to uniform the loads generated from the load- resisting bodies 9.

Description

[Detailed description of the invention] ! Industrial applications,.

The present invention relates to a ground anode car construction method for fixing above-ground structures, mountain retaining walls, etc. to the ground.

[Prior Art] Generally, a ground anchor is constructed by providing a retaining wall on the surface of the target ground, drilling an anchor hole in the ground, and inserting a plurality of anchor cables into the anchor hole, all the way to the bottom of the hole. Grout material such as concrete is injected into the ground, and after a curing period, the ends of the anchor cables that protrude outside the ground are tightened with a tree and held in that state to be anchored to the earth retaining wall. Ru.

Here, apart from temporary structures that have a lifespan of about two years,
When constructing a permanent anchor as a permanent structure, it is required that the anchor cable be treated with two or more layers of anti-corrosion treatment that is stable over a long period of time. There is a ground anchor structure.

Broadly speaking, the structures are known as tension type anchor structure and compression type anchor structure.

In the former method, the free length of the anchor cable is covered with a sheath tube, and the anchoring length is covered with a corrugated corrugated tube, and a grout material such as mortar is filled and solidified into the corrugated tube. It has a structure in which both are integrated and pulled together by an anchor cable. In addition, the latter covers the anchor cable with a source tube, and
A pressure-resistant member called a load-bearing body is attached to the entire outer periphery of the source pipe located in the anchor hole, which also serves as a rust-proof coating, and the end of the anchor cable is engaged with the underground end of this load-bearing body, and the inside of the source pipe is This structure compresses the load-bearing body within the grout in the anchor hole by tensioning the anchor cable without filling it with grout. In this case, the entire length of the anchor cable becomes the free length.

In the above-mentioned tension-type anchor structure, the anchor cable is triple-rust-proofed by the full-coated tube and the grout material inside and outside, or the load distribution to the grout material filled in the anchor hole is affected by the near side (ground surface The grout material in this area tends to crack or form easily.

Furthermore, the above-mentioned compression type anchor structure is subjected to triple rust prevention treatment using grout material in the source pipe, the load-bearing body, and the anchor hole.

The load distribution on the grout material is applied toward the back of the anchor hole, which is good for the anchor structure, but the load-bearing body attached to the source pipe is long.
Moreover, since this load-bearing body is generally made of steel, it is difficult to handle and construct.

Therefore, as a solution to the problem of this compression-type anchor structure, the load-bearing body attached to the source pipe is divided into multiple parts to reduce the size of the load-bearing body, and the number of anchor cables is reduced to the number of load-bearing bodies. An anchor construction method has been developed in which the anchor cables are divided into a plurality of corresponding sets, each set of anchor cables is fixed to each load-bearing body, and all the anchor cables are tensioned in this state. According to this, the load that each load-bearing body receives is small, and the load generated from the load-bearing body to the grout material in the anchor hole can be distributed approximately evenly, and handling and construction efficiency are also improved. There are some advantages to doing so.

[Problem to be Solved by the Invention] Incidentally, in the construction of a ground anchor, a tension confirmation test of the anchor cable is performed before tension fixation of the anchor cable. In this confirmation test, the tension load on the anchor cable is gradually increased by pulling and loosening the anchor cable, and the degree of anchorage of the underground end of the anchor cable is confirmed.

Specifically, when the design load of the earth anchor is 100%, first, 10% of the design load is set as the initial load.
The anchor cable 3 is pulled with a load of .

Then, at predetermined time intervals, the load is increased step by step while tensioning or loosening is performed. That is, the first stage is
After applying a 50% load and maintaining this state for several minutes, the load is lowered to 10% again.

In the next step, the load is increased to 70%, and after a few minutes it is relaxed to 10-. Next, increase the load to 100S and after a few minutes lO%
Loosen until In this way, the anchor cable 3 is repeatedly tensed and relaxed, and finally, after applying a load of 120%,
The load is lowered to around 'vi' and actual fixing is performed.

Therefore, in the case of a compression-type ground anchor structure in which anchor cables are engaged with multiple load-bearing bodies, as described above, the length of the anchor cable from the engagement part to each load-bearing body to the jar and cow is This free length is different for each anchor cable engaged with each load-bearing body, so the elongation and tension force of the anchor cable under tension are also different. come. Therefore, even when performing confirmation tests such as those mentioned above, in order to apply accurate loads to each anchor cable and load-bearing body, it is necessary to manage the tension of each anchor cable fixed to each load-bearing body. The problem is that it is extremely complicated and time-consuming.

As a solution to this problem, the Special Publication No. 53-4326
As shown in the publication, a technology in which a load-bearing plate with a spring mechanism is attached to an anchor cable (PC steel wire or steel bar) and an anchor pipe body is attached, and the overall pulling displacement is evenly distributed by a spring mechanism. According to this, when carrying out the above-mentioned confirmation test, it was not possible to keep the load acting on the load-bearing body uniform each time the tension was repeated, and for this reason, the length of the free length of the anchor cable Because it is not possible to specify the actual strain, it is difficult to obtain accurate measurement values during confirmation tests, and it is currently impossible to strictly control tension.

The present invention was made in view of the above-mentioned circumstances, and
As mentioned above, we developed a ground anchor construction method that can equalize the tension of anchor cables fixed to multiple load-bearing bodies and the load on the load-bearing bodies, and that can maintain this state even during confirmation tests, allowing reliable tension management. is intended to provide.

[Means for Solving the Problems] The present invention has been made to achieve the above object, and includes covering the anchor cables inserted into the anchor hole with a source tube, and covering the anchor cables with a source tube. A plurality of load-bearing bodies are attached to the pipe at regular intervals in the direction of tension of the anchor cable from the tip, and the plurality of anchor cables are divided into anchor cable groups of the same number as the load-bearing bodies, and each of these anchor cable groups is One set of the anchor cables is directly engaged with the load-bearing body installed on the underground end side, and the other anchor cable groups are each elastically deformed so that the tension of all the anchor cable groups is uniform. The anchor cables are characterized in that one pair of anchor cables is engaged with each of the other load-bearing bodies via a set elastic body, and then each anchor cable group is tensioned together.

[Function] According to the present invention, the elongation and tension of the anchor cables in each anchor cable group engaged with other load-bearing bodies except for the load-bearing body closest to the underground end are compensated for by the action of each elastic body. This corresponds to the elongation and tension of the anchor cable directly engaged with the load-bearing body closest to the underground end.

Once this is done, the extension and tension of the anchor cables in all the anchor cable groups will be uniform, and the loads generated on each load-bearing body will also be uniform, resulting in a good anchor structure. In addition, when performing confirmation tests before anchorage, the free length of the anchor cable can be determined as the distance from the load-bearing body closest to the underground end, allowing extremely accurate measurement values to be obtained and strict tension control. It can be performed.

[Example] Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

Fig. 1 shows the anchor structure obtained by the method of this example, where G is the target ground to which earth retaining is applied, 1 is the earth retaining wall provided on the surface of the target ground G, and 2 is the earth retaining wall installed on the target ground G. Anchor cables 3 are inserted into the drilled anchor hole 2 to the bottom of the hole, and the ends of these anchor cables 3 on the ground side are placed on a pedestal 4 and a pedestal 4 in contact with the earth retaining wall 1. The cable is passed through the throat 5 to the anchor and tensioned with a jack (not shown), and this state is fixed by engaging the wedge 6 attached to the outer periphery of the protruding end of the anchor cable 3 with the jaw 5 of the anchor. The end of the anchor cable 3 protruding from the throat 5 to the anchor is covered by an oil cap 7 fixed to the base 4.

The anchor cable 3 is a true PC strand made of stranded PC steel, and its surface is coated with a polyethylene tube and subjected to anti-rust treatment. Twelve anchor cables 3 are used in this embodiment.

These anchor cables 3 are inserted into a tube body 10 consisting of a source tube 8 and a plurality of load-bearing bodies 9 installed in the middle of the source tube 8, so that their entire length is covered by this tube body 10. ing.

The load-bearing body 9 is connected to the anchor cable 3 from the tip on the underground side.
In this embodiment, four are installed at regular intervals in the direction of tension. For the purpose of explanation, these load-bearing bodies 9 are referred to as a first load-bearing body 9A, a second load-bearing body 9B, a third load-bearing body 9C1, and a fourth load-bearing body 9D, in order from the tip side.

These load-bearing bodies 9 (9A, 9B, 9C19D) are made of tufftile cast iron and have a galvanized surface, and as shown in FIGS. 2, 5, and 6, the outer peripheral surface A large number of annular protrusions 9a having a diameter larger than that of the sheath tube 8 are formed at intervals in the axial direction, and the inner diameter of both ends forms a cylindrical shape between the outer diameter of the sheath tube 8 and the path. It is attached to the first tube 8 by fitting the second tube 8 to both ends thereof. Note that a pilot cap 11 that closes the opening is fitted to the tip of the load-bearing body 9A on the underground end side.

As shown in FIGS. 2 to 4, an engaging portion 12 for engaging the anchor cable 3 is integrally provided inside the load-bearing body 9.
The first
3 and a second insertion hole 14 through which the anchor cable 3 is simply inserted are formed through the load-bearing body 9 along the axial direction.

The first insertion holes 13 are formed at three locations equally dividing the circumferential direction in the outer wall portion of the engaging portion 9 . This first insertion hole 13 is continuous with a small diameter part +3a and a large diameter part 13b on the underground end side, and there is an annular engagement surface 13c orthogonal to the axial direction of the load-bearing body 9 between them. It is formed. Small diameter part 13
The inner diameter of a is slightly larger than the outer diameter of the anchor cable 3, and the inner diameter of the large diameter portion 13b is slightly larger than the outer diameter of the cylindrical combination grip 15 fixed to the outer periphery of the end of the anchor cable 3. It is set.

The second insertion hole 14 is located between each of the first insertion holes 13,
It is formed in a clover shape in cross section, and has three tip portions 14a.
, 14b, and 14c, three anchor cables 3 are inserted through each of them.

Incidentally, the 12 anchor cables 3 are divided into the same number of groups as the load-bearing bodies 9, that is, four groups each having three anchor cables.

Each set of these anchor cables 3 is a first anchor cable group 3A, a second anchor cable group 3B, and a third anchor cable R3C.

This is referred to as a fourth anchor cable group 3D.

As shown in FIGS. 2 and 6 to 8, the first anchor cable group 3A is directly engaged with the first load-bearing body 9A, and the second anchor cable group 3B is directly engaged with the second load-bearing body 9A. The third anchor cable group 3C is engaged with the body 9B via the load-bearing spring 16B, and the third anchor cable group 3C is engaged with the third load-bearing body 9C via the load-bearing spring 16.
The fourth anchor cable group 3D is engaged with the fourth load-bearing body 9D via the load-bearing spring 16D. FIG. 9 schematically shows the situation.

That is, each anchor cable 3 of the first anchor cable group 3A is passed through the first insertion hole 13 into the first load-bearing body 9, and one end surface of the combination grip 15 fixed to the tip is connected to the first insertion hole 13. Engagement surface 13c of insertion hole 13 of No. 1
By coming into contact with, it is engaged with the first load-bearing body 9A. These first anchor cable groups 3A are passed through the tip portions 14a of the second insertion holes 14 of the second load-bearing body 3B, the third load-bearing body 3C, and the fourth load-bearing body 3D, and 5 is engaged.

Further, a cylindrical load-bearing spring 16B is attached to the engagement surface 13 at the large diameter portion 13b of the first insertion hole I3 of the second load-bearing body 9B.
C, each anchor cable 3 of the second anchor cable group 3B is inserted in a state where it is in contact with the load-bearing spring 16.
B and the first insertion hole 13 respectively, and one end surface of the compressor/yong grip 15 abuts one end surface of the load-bearing spring 16B, thereby being engaged with the second load-bearing body 9B. These second anchor cable groups 3B
The load-bearing body 3C and the fourth load-bearing body 3D are passed through the tip portions 14b of the second insertion holes 14, and are engaged with the throats 5 of the anchors.

Further, a cylindrical load-bearing spring I6C is attached to the engagement surface 13 in the large diameter portion 13b of the first insertion hole 13 of the third load-bearing body 9C.
C, and each anchor cable 3 of the third anchor cable group 3C is inserted into the load-bearing spring 16
C and the first insertion hole 13, and one end surface of the spring 15 is engaged with the third load-bearing body 9C by abutting one end surface of the load-bearing spring 16C. These third anchor cable groups 3C
Each tip part 1 in each second insertion hole) 4 of the load-bearing body 3D
4C and is engaged with the anchor head 5.

Further, a cylindrical load-bearing hole 16D is inserted into the large diameter portion 13b of the first insertion hole 13 of the fourth load-bearing body 9D in a state in contact with the engagement surface 13c, and the fourth anchor Each anchor cable 3 of the cable group 3D is passed through the load-bearing spring +6D and the first insertion hole 13, and when one end surface of the combination knob 15 comes into contact with the one end surface of the load-bearing spring +6D, the fourth It is engaged with the load bearing body 9D. The anchor cables 3 of the fourth anchor cable group 3D are engaged with the anchor head 5 after passing through the first insertion hole 13 of the fourth load-bearing body 3D.

The ml load springs 16B, 16c, and 16D inserted into the large diameter portions 13b of the first insertion holes 13 of the second load-bearing body 9B, the second load-bearing body 9C, and the third load-bearing body 9D are the same as those described above. It has a cylindrical shape, and the anchor cable 3 is passed through it. Each of these load-bearing springs 16B, 16C, and 16D is an elastic body made of foamed NBR comb, and when the anchor cable 3 is tensioned, each of the combination springs fixed to the end of the anchor cable 3 Yonglinob 15
When pressed, it elastically deforms and contracts in the axial direction, and when the tension is released, it returns to its original state.

By the way, each anchor cable group 3A, 3B, 3C, 3D in the anchor cable 3... is connected to each load-bearing body 9A,
By engaging the ends of 9B and 9C19D,
The length up to the tension, that is, the length of the free length, is different. Therefore, each anchor cable group 3A
, 3B, 3C13D, load-bearing spring 16B, 16C116
When the anchor cables 3 are tensed by one tension without intervening D, the elongation (elongation rate) per unit length of the anchor cables 3 is constant. , 3B, 3C13D. That is, the elongation of the anchor cable 3 is proportional to its length, and the tension force is inversely proportional to its length.

Therefore, the length in the axial direction of each of the load-bearing springs 16B, 1.6 C116D is adjusted so that the tension and tension of the anchor cables 3 in the anchor cable groups 3B, 3C, and 3D are equal to those of the anchor cables 3 in the anchor cable group 3A. By making the difference, the amount of contraction (elastic deformation amount) can be changed.

For example, the anchor cable 3 of the first anchor cable group 3A has an outer diameter of 12.7 mm and a length (free length portion);
30m, breaking limit: 18.7tf, yield limit: 15.7
In the case of tf, when tensioned with a load of 14.3tf, the elongation is known to be 2+7+nm (theoretical value). When the length (between the front end faces) is 1 m, the elongation of each anchor cable 3 of the second, third, and fourth anchor cable groups 3B, 3C, and 3D is as follows:
1/30 (7.2 mm) and 2 mm, respectively, for the anchor cables 3 of the first anchor cable group 3A.
/30 (14.4 mm) and 3/30 (21.8 mm) are shown.

Therefore, under the conditions of the anchor cable 3 described above, if the distance between the load bearing bodies 9A, 9B, 9C19D is 1 m, the contraction amount of the load bearing spring 16B provided on the second load bearing body 9B is 7.2 mm. It is assumed that the load-bearing spring 16C provided on the third load-bearing body 9C is contracted by 14.4 m.
It is assumed that the load-bearing spring 1.6D provided on the fourth load-bearing body 9D is set to a contraction amount of 21.6 mm.

As a result, each anchor cable group 3A, 3B.

When 3C and 3D are tensioned together by one rope, the elongation of each anchor cable 3 of anchor cable groups 3B, 3C, and 3D is equal to each load-bearing spring 16B, 16C, +
6D, and both correspond to the elongation of the first anchor cable group 3A. Therefore, the tension generated in each anchor cable 3 of each anchor cable group 3A, 3B, 3C13D becomes uniform, and as a result, the load acting on the grout material in the anchor hole 2 from each load-bearing body 9A, 9B, 9C19D is also uniform. As a result, a good anchor structure can be obtained.

In addition, in the above, each load-bearing body 9A, 9B, 9C19D
Although an example is shown in which the mutual spacing is 1 m, this spacing is arbitrary, and each load-bearing spring 16B, 16C116
It is necessary to vary the amount of contraction of D.

For example, when the distance between the load-bearing bodies 9A, 9B, 9C, and 9D is 1.5 m, based on the above ratio, the amount of contraction is 1018 mm for the load-bearing spring 16B, and 1018 mm for the load-bearing spring 16B.
It is assumed that C is set to 21.6 mm and load-bearing spring 16D is set to 32.4 mm.

Furthermore, when conducting the confirmation test in which the anchor cable 3 is repeatedly tensioned as described in the [Problems to be Solved by the Invention] section, each load-bearing spring 16B, 16C, and 16D is Because it always returns to its original state,
The length (free length part) of anchor cable 3 is
, 9B, and 9C19D. Therefore, during confirmation tests, accurate measurement values can be obtained and strict tension management can be performed.

In addition, below, an example of the confirmation test method performed using the said construction method is demonstrated concretely.

First, the equipment used for this confirmation test will be explained.

Figure 10 shows a jar equipped with a shutter cage.

A state in which the cow 17 is set at the construction site is shown.

5 is the anchor head, and 4 is the pedestal.

The jack 17 includes a tension cylinder 18 for tensioning the anchor cable 3 and a push-in cylinder 20 for press-fitting the rust 6 into the throat 5 of the anchor, which are slidably fitted inside the cylindrical jack main body 17a. It is equipped.

At the upper opening of the tension cylinder 18, there is a 2 door 21 connected to the pooling ring.
are fitted. To this pooling.

The cable insertion hole 22 is provided in the card 21.
The upper part of 2 is a gripper hole 24 into which a wedge-shaped gripper 23 is fitted. Further, at the tip of the push-in cylinder 20, an index bell 26 in which a cable insertion hole 25 is provided is provided.

Furthermore, a cylindrical ram char 27, which is a pressure plate, is attached to the lower part of the jack body 17a. As shown in FIGS. 11 and 12, this ramchar 27 is
Frame portion 2 into which the lower edge of the jack body 17a is fitted into the upper edge
8, and an insertion opening 29 into which the anchor head 5 is inserted is formed at the bottom. A locking plate 30 for holding down the anchor head 5 is protruded from the inner peripheral surface.

What is indicated by the reference numeral 31 in FIG. 10 is the shutter gate. This shutter gate 31 is the thirteenth
As shown in the figure and FIG. 14, it has a long plate shape, and has a plurality of grooves 32 (four grooves in this case) formed in the longitudinal direction from the edge of the plate. This groove 32 is provided to correspond to the cable insertion hole 5a of the anchor head 5, and when the shutter gate 31 is placed on the anchor in alignment with the throat 5, the cable insertion holes 5a aligned in the same row are not aligned.
It is positioned above the groove 32 of the book.

Further, the groove width is formed to be slightly larger than the diameter of the anchor cable 3 and smaller than the diameter of the tip of the wedge 6, so that the anchor cable 3 can pass through, but the wedge 6 cannot pass through. When the shutter gate 31 is inserted, the portion through which the anchor cable 3 passes is defined as the penetration portion 33 of the anchor cable 3, and the wedge 6 is fitted into the upper surface of the shutter gate 31 around the penetration portion 33. A fitting recess 34 is formed.

Further, a handle portion 3 is provided at the other end of the shutter gate 31.
5 is formed, and by grasping this part and inserting/removing the shutter gate 31 from/to the anchor cable 3, the shutter gate 31 connects to the anchor at the throat 5.
It is designed to be removably placed on the top surface of the .

Note that, as shown in FIG. 12, a gate insertion hole 36 for inserting the shutter gate 31 is formed in the peripheral wall of the ram char 27.

Next, the operation of the jack 17 configured as described above and the confirmation test method described above will be explained according to the operating procedure.

First, as shown in FIG. 10, the /yanogyu 17 is attached to the end of the anchor cable 3 that protrudes outside the ground. To do this, first, the anchor cable 3 is passed through the cable insertion hole 1a of the anchor plate retaining wall 1, and then taken out from the cable insertion hole 5a of the anchor head 5.

Next, the wedge 6 is passed from the end of the anchor cable 3 into the anchor with the tip facing toward the throat 5, and is attached to the anchor cable 3 by winding a spring (as shown) near the throat 5 to the anchor.

Then, pass the anchor cable 3 through the cable insertion hole 25 of the index plate 26, and from inside the tension cylinder 18,
The cable is passed through the cable insertion hole 22 of the pooling head 21 to the outside. Then, by fitting the gripper 23 into the gripper hole 24 of the pooling head 21, the gripper 17 is fixed to the anchor cable 3.

Next, the operating procedure of the tensile test method will be explained.

First, insert the target 31 through the gate insertion hole 36 of the ram chart 27 and attach it to the anchor.

5 and wedge 60. At this time, the anchor cable 3 enters the groove 32 of the nosenotarcate 31. In this state, the tension/relaxation of the anchor cable 3 is performed by operating the tension/link 18 every cycle of the tensile test described above.

The operation of the wedge 6 and the turret 31 at this time will be explained. First, when the anchor cable 3 is tensioned, the wedge 6 moves as the anchor cable 3 is stretched. However, since the distance between the target plate 31 and the Intex plate 26 is set shorter than the extension of the anchor cable 3 in one pull, the wedge 6 either moves with the anchor cable 3 to some extent or stops when it hits the index plate 26. do. When the anchor cable 3 is further tightened, the anchor cable 3 stretches, but the wedge 6 remains in front of the index plate 26.

After the anchor cable 3 is pulled while maintaining a predetermined load in this manner, the load is lowered. Then, as the anchor cable 3 shrinks, the wedge 6 moves toward the anchor throat 5, or its tip fits into the recess 34 formed in the penetration part 33 of the target gate 31, and it does not move any further. .

The wedge 6 moves as described above when tensioning and relaxing the anchor cable 3, and the wedge 6 does not fit into the wedge hole 5b of the anchor head 5 due to the turret 31. In other words, the anchor cable 3 is not fixed during the test. never be done.

In this way, during the confirmation test, by placing the shutter gate 31 on the anchor head 5,
The wedge 6 can be tensioned and relaxed continuously without being inserted into the wedge hole 5b of the throat 5 of the anchor.

In addition, in order to carry out actual anchoring after the test, after performing the final tension in the test, pull out the anchor gate 31 from the gate insertion hole 36 of the ram char 27, and apply the tension load of the anchor cable 3 to a predetermined value. Return to fixed load,
The wedge 6 is press-fitted into the wedge hole 5b of the anchor head 5 by the push-in link 20.

According to this confirmation test method, anchor cable 3
When the tension of the anchor cable 3 is relaxed, the tension of the anchor cable 3 is reduced with the wedge 6 still attached to the anchor cable 3, since the wedge 6 does not fit into the wedge hole 5b of the anchor head 5 due to the turret 31. Go on, again
After the test, when actually fixing the anchor cable 3, it is sufficient to remove the shaft and the turret 31, and insert the wedge 6 into the anchor into the wedge hole 5b of the anchor 5.

However, from the confirmation test to the actual establishment, -
The work can be carried out continuously throughout the area, greatly improving the work efficiency of ground anchor construction. By performing this in combination with the ground anchor method of the present embodiment described above, accurate measurement values can be obtained during the confirmation test, and strict tension management can be performed.

[Effects of the Invention] As explained above, according to the ground anchor construction method of the present invention, a plurality of anchor cables to be inserted into an anchor hole are wave layered by a 7-sheath pipe, and a wave layer is applied to the sheath pipe from the tip. A plurality of load bearing bodies are installed at regular intervals in the tension direction of the anchor cable, the plurality of anchor cables are divided into anchor cable groups of the same number as the load bearing bodies, and one set of these anchor cable groups is attached. An elastic body that directly engages with the load-bearing body installed closest to the underground end, and that also connects other anchor cable groups, with the amount of elastic deformation set so that the tension of all anchor cable groups is uniform. The method is characterized in that one pair of anchor cables is engaged with each of the other load-bearing bodies via the anchor cables, and then each group of anchor cables is tensed together, so that the anchor cables are engaged with a plurality of load-bearing bodies by the action of each elastic body. The elongation and tension of the anchor cables in each anchor cable group are uniform, and as a result,
The load generated from the load-bearing body becomes uniform, making it possible to obtain an excellent ground anchor structure.In addition, the elongation and tension of the anchor cable can be adjusted to theoretical values even during confirmation tests before anchorage, in which the anchor cable is repeatedly tensed and relaxed. It can be approximated and has the effect of ensuring reliable tension management.

[Brief explanation of the drawing]

FIG. 1 is a partially sectional side view of a ground anchor structure constructed according to an embodiment of the present invention, FIG. 2 is a partially sectional side view of the first load-bearing body, and FIG. Fig. 4 is a view taken along the ■-■ line in Fig. 2, Fig. 5 is a view taken along the -v line in Fig. 2, and Fig. 6 is a view taken along the line ■-v in Fig. 2. 7 is a partially sectional side view of the third load bearing body; FIG. 8 is a partially sectional side view of the fourth load bearing body; FIG. 9 is a schematic diagram of the anchor structure; Figures 1 to 14 are diagrams for explaining the confirmation test.
The figure is a plan view of the ram char, FIG. 12 is a side view of the left half of the ram char in cross section, FIG. 13 is a plan view of the shutter cage, and FIG. 14 is a view taken along the Z-Z line in FIG. 13. 2.-Anchor hole, 3 ... Anchor cable, 8
...Nose pipe, 9 (9A, 9B, 9C19D)...Load-bearing body, 16B, 16C, 16D...Load-bearing spring (elastic body), G... Ground. Figure 6

Claims (1)

[Claims] A plurality of anchor cables to be inserted into the anchor hole are covered with a sheath tube, and a plurality of load-bearing bodies are attached to the sheath tube at regular intervals from the tip in the tension direction of the anchor cable, and the plurality of load bearing bodies are The anchor cables are divided into the same number of anchor cable groups as the load-bearing bodies, and one set of these anchor cable groups is directly engaged with the load-bearing body installed closest to the underground end, and the other anchor cable groups are , one pair of anchor cables is engaged with each of the other load-bearing bodies via elastic bodies each having a set amount of elastic deformation so that the tension force of all the sets of anchor cable groups is uniform;
Next is the ground anchor construction method, which is characterized by tensioning each anchor cable group together.