JPH1143940A - Ground anchor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a ground anchor in which friction resistance can be improved while correctly maintaining grout strength by uniformly generating the friction resistance along the whole length of an anchor body. SOLUTION: Plural knot parts 17, 18 are provided at an interval in an axial line direction at a tip part of a tension member 16, the knot parts 17, 18 are respectively enclosed in plural load-resistant cylinders 20, 21 serially connected to each other by a hollow connection cylinder 19 to be freely movable in the axial line direction, and elastic members 24, 25 for dispersing tensile load generated by pull of the tension member 16 are disposed in elastic member containing spaces 22, 23 formed on the anchor head part 10 side in the respective load- resistant cylinders 20, 21. Tensile load is thus uniformly dispersed along the whole body of a load-resistant body to be transmitted to grout 15 around it.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a slope stabilization work using a cast-in-place frame or a PC frame, reinforcement of an existing retaining wall, reinforcement of an existing masonry, reinforcement of a bridge foundation, anchor of a suspension bridge, floating of an underground structure. The present invention relates to a ground anchor that can be used for prevention of an overturn, a fall of a steel tower, and the like.

[0002]

2. Description of the Related Art There is a friction type ground anchor as one form of a ground anchor provided for the above-mentioned purpose. This ground anchor is a tension type ground anchor 50 shown in FIG.
And a ground anchor 60 of a compression type shown in FIG. As shown in FIG. 20 and FIG. 21, the ground anchors 50 and 60 are composed of three parts: anchor heads 51 and 61, free lengths 52 and 62 of underground parts, and anchor bodies 53 and 63. . Here, the anchor heads 51, 61
Is a portion that applies a tensile load (tensile force) to the tensile members 54 and 64 such as deformed PC steel rods, and has a role of transmitting the tensile load to the structures 55 and 65. On the other hand, the free length portions 52, 62 have a role of transmitting the tensile load from the anchor heads 51, 61 to the anchor bodies 53, 63, and the anchor bodies 53, 63 transmit the tensile load to the ground 5
6 and 66.

[0003] The ground anchor 50 having the above structure,
In the case of the tension type ground anchor 50, first, as shown in FIG. 20, when a tensile load is applied to the tensile member 54, the maximum tensile force is generated near the boundary 57 between the free length portion 52 and the anchor body 53. Will work. This maximum tensile force is transmitted to the grout (hardened cement milk) 58, which is transmitted to the ground 56 to generate a frictional resistance (shear). Note that FIG.
In S1, S1 shows a distribution curve indicating such frictional resistance.

On the other hand, as shown in FIG. 21, in the case of a compression type ground anchor 60, the tip end of a tensile member 64 is
When a tensile load is applied to the tensile member 64, the load bearing member 67 is lifted from below, and a compressive force acts on the grout 68 around the load bearing member 67,
It is transmitted to the ground 66 to generate a frictional resistance (shearing force).
In addition, as is clear from the distribution curve S2 of the frictional resistance shown in FIG.

[0005]

However, the above-described ground anchors 50 and 60 still have the following problems to be solved. That is, as is clear from the frictional resistance distribution curves S1 and S2 shown in FIGS. 20 and 21, in each of the above-described ground anchors 50 and 60, the frictional resistance is evenly distributed over the entire length of the anchor bodies 53 and 63. Ground 5
6, 66 is difficult to act, and the frictional resistance is locally concentrated. Therefore, if the adhesive force and strength of the grouts 58 and 68 are not large, the grouts 58 and 68 are broken and the action part of the frictional resistance moves, and if this progresses, the anchor bodies 53 and 63 may also collapse. Become.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and aims to increase the frictional resistance while appropriately maintaining the strength of the grout by dispersing the frictional resistance almost uniformly over the entire length of the anchor body. It is an object of the present invention to provide a ground anchor that can be used.

[0007]

According to the present invention, there is provided a semiconductor device comprising:
The ground anchor according to the invention is a ground anchor composed of an anchor head connected in series, a free length portion of an underground portion, and three portions of an anchor body, wherein the anchor head passes through the free length portion from the anchor head. At the tip of the tension member extending to the anchor body, a plurality of nodes having a larger diameter than the tension member are provided at intervals in the axial direction, and each of the nodes is connected in series by a hollow connection tube. A tensile load generated by pulling the tension member is enclosed in an elastic member storage space formed in the load-carrying cylinder so as to be movable in the axial direction one by one and formed on the anchor head side in each of the load-carrying cylinders. An elastic member for dispersing and transmitting to the load-carrying cylinders is provided.

[0008] The ground anchor according to the second aspect is the first aspect.
In the described ground anchor, the elastic member is a disc spring. A ground anchor according to a third aspect is the ground anchor according to the second aspect, wherein the number of the disc springs is adjusted according to the tensile load. The ground anchor according to claim 4 is the ground anchor according to any one of claims 1 to 3, wherein the tension member is formed of a steel rod having a total screw, and the node section includes a fixing nut that connects the fixing nut to the tension member. It is formed by screwing on the tip.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described with reference to the accompanying drawings to provide an understanding of the present invention. First, a configuration of a ground anchor A according to an embodiment of the present invention will be described with reference to FIGS. In the present embodiment, a ground anchor A is used for a slope C of a retaining wall B which is a structure.

As shown in FIG. 1, a ground anchor A according to the present embodiment includes an anchor head 10 and a free length portion 11.
And the three portions of the anchor body 12 are connected in series. Free length 11 and anchor 1
2 is inserted into an excavation hole 14 excavated in the ground 13,
Further, a grout 15 is formed by filling and solidifying cement milk in a space formed between the inner peripheral surface of the excavation hole 14 and the outer peripheral surfaces of the free length portion 11 and the anchor body 12.

FIGS. 1 to 3 show the structure of the anchor body 12 of the ground anchor A having the above-described basic structure.
As shown, the anchor body 12 has substantially the following configuration. That is, the tip of the tension member 16 extends from the anchor head 10 to the tip of the drilling hole 14 through the free length portion 11, and has a larger diameter than the tension member 16 at an interval in the axial direction. Fixing nuts 17, 18 are provided as examples of the plurality of joints. Each fixing nut 1
Reference numerals 7 and 18 denote spring cases 20 and 21 which are examples of a plurality of load-carrying tubes connected in series by a hollow connection tube 19.
Each is movably surrounded in the axial direction. In order to disperse the tensile load generated by pulling the tension member 16, the spring storage spaces 22 and 23, which are examples of the elastic member storage spaces formed on the anchor head 10 side in the spring cases 20 and 21, respectively. Disc springs 24 and 25, which are examples of the elastic member, are provided. Note that a load-bearing body is formed by the hollow connection cylinder 19 and the spring case 21. Similarly, a load-bearing body is formed by the later-described hollow connecting cylinder 28 and the spring case 20.

Referring to FIGS. 2 to 12, the structure of the above-described anchor body 12 will be described in more detail. 2 and 11
As shown in FIG. 12, the rear portion of the hollow connecting tube 28 is coaxially connected via a sheath coupling 27 to the leading end of a long sheath pipe 26 forming the main body of the free length portion 11.

As shown in FIG. 2, a rear portion 20a of the spring case 20 is screwed to a front portion of the hollow connecting cylinder 28. As shown in FIGS. 2 and 10, a lock nut 29 is screwed to a portion of the tension member 16 corresponding to the front end of the hollow connection cylinder 28, so that the spring case 20 does not move when the fixing nut 17 is tightened. I have to. FIG. 2 and FIG.
As shown in FIG. 5, wings 30 are provided at the rear portion 20a of the spring case 20 at circumferential intervals so as to increase the area of attachment to the grout 15.

As shown in FIGS. 2, 5, and 6, an enlarged-diameter tube portion 31 is formed at the tip of the spring case 20, and a fixed nut that also functions as a spring retainer is provided in the enlarged-diameter tube portion 31. 17 is provided, and the fixing nut 17 is
Is screwed on. A spring storage space 22 is formed between the rear annular wall of the enlarged diameter cylindrical portion 31 and the rear surface of the fixed nut 17.
4 are stored.

As shown in FIG. 2 and FIG.
The rear end of the hollow connection tube 19 having the cross-sectional shape shown in FIG. 9 is connected via a coupling 33 to the front end of the enlarged diameter tube portion 31 forming the front end of the cylinder.

As shown in FIGS. 2 and 8, the hollow connecting cylinder 1
A rear portion 21a of the spring case 21 is screwed to the front end of the screw case 9. Similarly to the spring case 20, wings 34 are provided at the rear portion 21a of the spring case 21 at circumferential intervals so as to increase the area of attachment to the grout 15.

As shown in FIG. 2, an enlarged diameter cylindrical portion 35 is formed at the tip of the spring case 21, and a fixed nut 18 is disposed in the enlarged diameter cylindrical portion 35 as a spring holder.
The fixing nut 18 is screwed to the tension member 16. A spring storage space 23 is formed between the rear annular wall of the enlarged diameter cylindrical portion 35 and the rear surface of the fixed nut 18, and a disc spring 25 is stored in the spring storage space 23.

As shown in FIG. 2, a coupling 36 is provided at the front end of the enlarged diameter cylindrical portion 35 forming the front end of the spring case 21.
, The tip cap 37 is screwed. Also,
A spring storage space 2 is provided on the rear surface of the spring cases 20 and 21.
Nipples 38 and 39 for filling anticorrosive grease and the like are mounted inside 2, 23 and the like.

Next, a procedure for assembling the above-described anchor body 12 and a procedure for connecting the anchor body 12 to the free length portion 11 after assembly will be described. First, a lock nut 29 is screwed into a predetermined position of the tension member 16, and the lock nut 2 is
9, and then the hollow connecting tube 28 is connected to the tension member 16.
, And the rear part of the spring case 21 is screwed to the front part of the hollow connection cylinder 28. As shown in FIG. 3, in a state where the disc spring 24 is mounted on the outer peripheral surface of the small-diameter cylindrical portion 17 a of the fixing nut 17, the fixing nut 17 is screwed into the tension member 16 and the inside of the enlarged-diameter cylindrical portion 31 of the spring case 20. To fit. At this time, after the disc spring 24, the fixing nut 1 is fixed until the front end surface thereof comes into contact with the rear annular wall of the enlarged diameter cylindrical portion 31 and the rear surface of the fixing nut 17, respectively.
7 is screwed. The rear part of the hollow connecting cylinder 19 is connected to the front end of the enlarged diameter cylindrical part 31 of the spring case 20 via a coupling 33. The rear part of the spring case 21 is screwed to the front part of the hollow connecting cylinder 19. In the enlarged diameter cylindrical portion 35 of the spring case 21,
A fixing nut 18 with a disc spring 25 is fitted on the outer peripheral surface of the small-diameter cylindrical portion 18a while being screwed to the tension member 16. At this time, after the disc spring 25, the fixing nut 18 is screwed in until the front end faces respectively contact the rear annular wall of the enlarged diameter cylindrical portion 35 and the rear surface of the fixing nut 18. The anchor body 12 can be assembled by screwing the distal end cap 37 through the coupling 36 to the front end of the enlarged-diameter cylindrical portion 35 forming the front end of the spring case 21.

Thereafter, the rear part of the hollow connecting cylinder 28 forming the last member of the anchor body 12 is connected to the sheath coupling 27.
The sheath pipe 26 of the free length portion 11 can be connected to the anchor body 12 by connecting the sheath pipe 26 to the sheath pipe 26 by using a wire. The tensile member 16 is a sheath pipe 2
In 6, the addition using a coupler is the same as in the prior art.

Next, the operation of the ground anchor A having the above configuration will be described with reference to FIG.

In FIG. 13, when a tensile load is applied to the tensile member 16, the conical spring 2
The load is transmitted to 4 and 25. The coned disc springs 24 and 25 are naturally bent, and the reaction force is transmitted to the spring cases 20 and 21. Here, as long as the amount of deflection of the disc springs 24 and 25 remains, that is, as long as the flat springs are not completely flattened by the load, the tensile load is applied to each spring case 2 which is a load-resistant cylinder.
0 and 21 act almost equally. As described above, in the present embodiment, the tensile load is applied to the hollow connecting cylinder 1.
9 and a load-bearing body formed by the spring case 21;
The load is distributed to the surrounding grout 15 on the load-bearing body formed by the hollow connecting cylinder 28 and the spring case 20 on average. Accordingly, as can be understood from the distribution curve S of the frictional resistance (shearing force) shown in FIG. 13, the frictional resistance is also averaged over the entire load-bearing body, so that destruction of the grout 15 due to local concentration of the frictional resistance is prevented. Can be prevented,
Destruction of the anchor body 12 due to such destruction can also be reliably prevented.

FIG. 14 shows a ground anchor A1 according to a modification of the present embodiment. As shown in FIG.
The anchor body 40 has the same configuration as the anchor body 12 of the ground anchor A according to the above-described embodiment, and has fixed nuts 41a, 42a, 43a as an example of a node portion and spring cases 41b, 42b as an example of a load-carrying cylinder. , 43b and disc springs 41c, 42c as an example of an elastic member. In FIG. 14, the combined body 43 formed at the foremost portion is shown.
Although a disc spring 43c, which is an example of an elastic member, is not mounted in the spring case 43b, a disc spring 43c may be provided as shown in FIG. FIG.
As shown in the figure, the load-carrying tubes 41b, 42b, 43b are connected to each other by intermediate connecting tubes 42d, 43d, and the load-bearing tube 41b is connected to the free length portion 11a by the intermediate connecting tube 41d. Then, the fireproof cylinder 42b and the intermediate connecting cylinder 42 are formed by the fireproof cylinder 41b and the intermediate connecting cylinder 41d.
With d, a load-bearing body is formed by the load-bearing tube 43b and the intermediate connecting tube 43d. With such a configuration, the frictional resistance received by the ground anchor A1 is averaged for the three load-bearing bodies, and the grout 15 can be more effectively prevented from being broken due to local concentration of the frictional resistance. Breakage of the anchor body 40 due to excessive breakage can be more reliably prevented. The distribution curve Sa of the frictional resistance is as shown in FIG.

In order to confirm the uniform effect of the frictional resistance by the ground anchor A1 according to the modification of FIG. 14, FIG.
7 and an equal effect of the frictional resistance by the ground anchors A2 and A3 shown in FIG. The ground anchor A2 shown in FIG. 17 is characterized in that the anchor body 44 includes only three nodes 45 to 47 having the same configuration as the nodes according to the above-described embodiment. The ground anchor A3 shown in FIG. 18 is different from the anchor body 12 of the ground anchor A according to the above-described embodiment in that the anchor body 48 is provided with a combination body including only the nodes 48a to 48c and the load-bearing cylinders 49a to 49c. It is characterized by having.

In the ground anchor A2 shown in FIG. 17, when a tensile load is applied to the tensile member 16, the joint 45
Although it is considered that the pulling force is applied to each of the 47 and the frictional resistance force is likely to be dispersed, the pulling force acts mainly in the vicinity of a and transmits the pulling force equally to all the nodes 45 to 47. It is difficult to do. That is, the distribution curve Sb of the frictional resistance is as shown in FIG.

On the other hand, in the ground anchor A3 shown in FIG. 18, when a tensile load is applied to the tension member 16, the nodes 48a to 48c come into contact with the load-carrying tubes 49a to 49c, respectively. Therefore, also in this case, it is difficult for the pulling force to act mainly on the vicinity of b in practice, and to transmit the pulling force uniformly to all the combined bodies. That is, the distribution curve Sc of the frictional resistance is as shown in FIG.

In the modification shown in FIG. 14, a lock nut 29 corresponding to the lock nut 29 shown in FIG.
a is provided at the tip of the sheath pipe 26a that forms the free length portion 11a.

In the above-described embodiment and its modifications, by appropriately combining the disc springs 24 (the same applies to 25, 41c, 42c and 43c), it is possible to obtain a predetermined amount of deflection suitable for the installation conditions of the ground anchors A and A1. A reaction force can be obtained.

FIG. 19 shows the specific shape and assembly structure of the disc spring 24. FIG. 19A shows a case where two disc springs 24 are assembled in two stages in series, and FIG. 19B shows a case where three disc springs 24 are assembled in three stages in series.
FIG. 19 (c) shows a case where three disc springs 24 are assembled in parallel and one stage, and FIG. 19 (d) shows a case where three springs 24 are assembled in parallel and three stages in series.

However, the present invention is not limited to these combinations at all, and other combinations, for example, four or more stages may be used depending on the use conditions. Even in this case, since each disc spring 24 is thin (3 to 5 mm / sheet), the spring case 20 can be held in a relatively compact shape. Further, in the present embodiment, the tension member 16 is formed from a steel bar (PC steel bar) having a total screw, and the nodes are formed by the fixing nuts 17 and 18, so that the nodes are formed on the anchor body 12. Work can be done easily, accurately and quickly.

As described above, the present invention has been described with reference to one embodiment. However, the present invention is not limited to the configuration described in the above embodiment, and is described in the claims. It also includes other embodiments and modifications that can be considered within the scope of the matters described. For example, in the above-described embodiment, the disc spring is used as the elastic member for transmitting the tensile load from the node portion to the load-bearing body while dispersing the load, but a coil spring or the like may be used instead of the disc spring. . Further, in the above-described embodiment and the modified example, two or three nodes are provided at the tip of the ground anchor at intervals in the axial direction. Can also.

[0032]

In the ground anchor according to any one of the first to fourth aspects, a plurality of nodes are provided at intervals in the axial direction at the leading end of the tensile member serving as the anchor anchoring portion, and each node is hollowly connected. A plurality of load-carrying cylinders connected in series by a cylinder are surrounded one by one movably in the axial direction, and in the elastic member storage space formed on the anchor head side in each load-carrying cylinder,
An elastic member is provided for dispersing a tensile load generated by pulling the tensile member. Therefore, the tensile load is transmitted to the surrounding grout while being dispersed evenly throughout the load-bearing body, so that the grout can be prevented from being broken due to the local concentration of frictional resistance, and the anchor caused by such a break can be prevented. It can also reliably prevent destruction of the body,
A stable ground anchor can be constructed.

[0033] In the ground anchor according to claim 2,
By forming the elastic member from a disc spring, the load-bearing body can be held in a compact structure. In the ground anchor according to the third aspect, by adjusting the number of disc springs according to the tensile load, it is possible to adjust the reaction force of the disc spring so as to meet the installation conditions of the ground anchor. In the ground anchor according to claim 4, the tension member is formed from a steel bar having a total screw, and the node is formed by a fixing nut screwed to a tip of the tension member, thereby forming the node to the anchor body. The forming operation can be performed easily, accurately, and quickly.

[Brief description of the drawings]

FIG. 1 is a side view of a ground anchor according to an embodiment of the present invention.

FIG. 2 is a half sectional view of the main part.

FIG. 3 is a sectional view of a main part of the anchor body.

FIG. 4 is a sectional view taken along line II of FIG. 3;

FIG. 5 is a sectional view taken along line II-II of FIG.

FIG. 6 is a sectional view taken along line III-III in FIG. 3;

FIG. 7 is a sectional view taken along the line IV-IV in FIG. 3;

FIG. 8 is a sectional view taken along line VV in FIG. 2;

FIG. 9 is a sectional view taken along line VI-VI of FIG. 2;

FIG. 10 is a sectional view taken along line VII-VII in FIG. 2;

11 is a sectional view taken along line VIII-VIII in FIG.

FIG. 12 is a sectional view taken along line IX-IX in FIG. 2;

FIG. 13 is an explanatory diagram showing a distribution state of frictional resistance by the ground anchor according to one embodiment of the present invention.

FIG. 14 is a half sectional side view of a ground anchor according to a modified example of one embodiment of the present invention.

FIG. 15 is a half sectional side view of a ground anchor according to a modification of the embodiment of the present invention when the most advanced combination body has an elastic member.

FIG. 16 is an explanatory diagram showing a distribution state of frictional resistance by a ground anchor according to a modified example of one embodiment of the present invention.

FIG. 17 is an explanatory diagram of a ground anchor according to a comparative example.

FIG. 18 is an explanatory diagram of a ground anchor according to a comparative example.

FIG. 19 is an explanatory diagram showing a specific configuration of a disc spring.

FIG. 20 is a side view showing a state where a conventional ground anchor is installed.

FIG. 21 is a side view showing a state where a conventional ground anchor is installed.

[Explanation of symbols]

Reference Signs List A Ground anchor A1 Ground anchor B Retaining wall C Slope S Distribution curve Sa Distribution curve 10 Anchor head 11 Free length part 11a Free length part 12 Anchor body 13 Ground 14 Excavation hole 15 Grout 16 Tensile material 17 Fixing nut (node) 17a Small-diameter tube portion 18 Fixing nut (node) 18a Small-diameter tube portion 19 Hollow connection tube 20 Spring case (load-carrying tube) 20a Rear portion 21 Spring case (load-carrying tube) 21a Rear portion 22 Spring storage space (elastic member storage space) 23 Spring storage space ( Elastic member storage space) 24 Belleville spring (elastic member) 25 Belleville spring (elastic member) 26 Sheath pipe 26a Sheath pipe 27 Sheath coupling 28 Hollow connecting cylinder 29 Lock nut 29a Lock nut 30 Wing 31 Large diameter cylinder 33 Coupling 34 Wing 35 Enlarged cylinder 36 Coupling 7 Tip Cap 38 Nipple 39 Nipple 40 Anchor 41 Combination 41a Fixing Nut 41b Spring Case 41c Belleville Spring 41d Intermediate Connection Tube 42 Combination 42a Fixed Nut 42b Spring Case 42c Belleville Spring 42d Intermediate Connection Tube 43 Combination 43a Fixing Nut 43b 43 Spring 43d Intermediate connecting cylinder

Claims (4)

[Claims] 1. A ground anchor composed of an anchor head connected in series, a free length portion of an underground portion, and three portions of an anchor body, wherein the anchor is passed through the free length portion from the anchor head. At the tip of the tension member extending to the body, a plurality of nodes having a larger diameter than the tension member are provided at intervals in the axial direction,
Each of the joint portions is surrounded by a plurality of load-carrying tubes connected in series by a hollow connecting tube so as to be movable in the axial direction one by one, and an elastic member formed on an anchor head side in each of the load-bearing tubes. A ground anchor, wherein an elastic member for dispersing a tensile load generated by pulling the tensile member and transmitting the tensile load to the load-carrying cylinders is provided in the storage space. 2. The ground anchor according to claim 1, wherein said elastic member is a disc spring. 3. The ground anchor according to claim 2, wherein the number of the disc springs is adjusted according to the tensile load. 4. The tension member is formed of a steel rod having a total screw, and the node is formed by screwing a fixing nut to a tip of the tension member. The ground anchor according to any one of the above items.