JP2743819B2 - Ground anchoring part of ground anchor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a head anchoring portion of a ground anchor.

[0002]

2. Description of the Related Art In general, as a head anchoring portion of a ground anchor, an anchoring plate and an anchoring plate are used, and an end of a stranded PC steel wire is anchored in an anchoring hole of the anchoring plate by a wedge through the anchoring plate. It is.

[0003]

In the conventional system, the PC
The bending moment of the bearing plate and anchoring plate and the compressive stress of the structural concrete immediately below resist the tension introduced into the steel stranded wire, and both members require high strength and large cross sections. As the size of a product increases, the tendency increases, leading to an increase in cost.

[0004] Further, since the pressure supporting plate and the fixing plate become huge when the anchor becomes large, it cannot be used for a large anchor at present.

[0005]

SUMMARY OF THE INVENTION The present invention relates to a structure of an anchor head anchoring portion which uses a load-bearing member, which is a steel pipe, for the anchoring portion of an anchor head to distribute stress and consequently obtains a large anchoring force. It is about.

That is, according to the present invention, a load-bearing body (steel pipe) in which one unbonded steel stranded wire is inserted is buried in the structural concrete so that the upper end surface is exposed to the upper surface of the structural concrete. A fixing plate with a fixing hole is placed on top of it, and while applying tension to the steel stranded wire penetrating the fixing hole, the end part of the ground anchor where the end of the steel stranded wire is fixed to the fixing hole with a wedge. It is.

According to the present invention, the tension introduced into the stranded PC steel is shared by the bending moment of the fixing plate, the compressive stress of the structural concrete immediately below the fixing plate, and the compressive stress of the structural concrete around the load-bearing body. Therefore, the use of a high-strength, large-section supporting plate is not required. It is possible to reduce the size of the fixing device with respect to the same tension as in the related art, and it is possible to withstand a larger tension with a fixing device having the same size as the related art. As a result, the present invention can be applied to a large anchor which cannot be used in the conventional one.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings.

FIG. 1 is a longitudinal sectional view of an example of a fixing section in which both ends of a ground anchor are fixed, and FIG. 2A is an enlarged longitudinal sectional view around a fixing hole showing an example of a head fixing section. FIG.
(B) is a plan view of an example of a fixing plate used for fixing.

In the example shown in FIG. 1, a cast-in-place concrete pile 2 also serves as a ground anchor body, on which an underground beam 1 is constructed. I have.

The procedure for fixing the head of the ground anchor according to the present invention will be described.

(1) Each unbonded steel stranded wire 4 buried in the cast-in-place concrete pile 2 has a load-bearing body 3A
Then, it is installed together with a reinforcing bar at a predetermined position of the underground beam 1 and casts underground beam concrete. It is preferable to vary the length of the load-carrying bodies 3A to be covered one by one from the viewpoint of widely dispersing the compressive stress.

(2) The upper surface of the underground beam 1 is finished so that the upper surface of the underground beam 1 is flush with the upper end surface of the buried load-bearing body 3A.

(3) The template 6 and the fixing plate 5 are placed while inserting the unbonded steel stranded wires 4 into the respective holes. The sheath 4A at the end of each unbonded steel stranded wire 4 is peeled off, pulled by a jack to introduce a predetermined tension, and the wedge 7 is driven into the fixing hole 8 of the fixing plate 5 for fixing.

(4) Although not shown, fixing is completed by performing necessary operations such as mounting a protective cover on the fixing plate 5 and enclosing rust preventive oil into the protective cover.

FIG. 2 (b) shows an example of the fixing plate 5, in which a number of fixing holes 8 are formed in a donut-shaped disk with a taper. In this example, 24 fixing holes 8 are provided, but the number is appropriately determined. In extreme cases, one may be used. However, the fixing plate 5 having a large number of fixing holes 8
It is efficient to use

In this example, a donut-shaped disk is shown. However, the disk may be a donut-shaped disk having no empty space in the center, and may have a shape other than the disk.

FIG. 1 shows a ground anchor body (in this example, a cast-in-place concrete pile 2 is also used.

Although an example of the fixing unit on the side of ()) is shown, it has nothing to do with the present invention, but a supplementary explanation will be given.

The ground anchor body-side fixing section is a mixed type fixing section in which a tension type and a compression type are mixed.

A number of holes are drilled in the support plate 9, and among these holes, the unbonded steel stranded wire 4 with an end sheath inserted is inserted through the tension-type holes, and the compression-type holes are inserted into the other compression-type holes. The end of the unbonded steel stranded wire 4 is fixed, and the load-bearing body 3B is vertically fixed to the supporting plate 9 so as to cover around the unbonded steel stranded wire 4 in the compression mold hole as in the present invention. .

In the tension type anchoring portion of the anchoring portion on the ground anchor body side, not only the unbonded steel stranded wire 4 having the sheath at the end but also a deformed steel rod (not shown) and a PC steel material can be used. When a steel bar is used, it is connected to the unbonded steel stranded wire 4 by a connector (not shown) above the fixing portion.

The use of a mixed type fixing section as the ground anchor body side fixing section is merely an example. In the present invention, the type of the ground anchor body side fixing section may be any of a tension type, a compression type and a mixed type.

[0024]

According to the present invention, the load-bearing body is buried in the structure at the ground anchor anchoring portion on the structure side so as to surround the individual PC steel stranded wire, so that the tension introduced into the PC steel stranded wire is provided. The force is shared and resisted by the bending moment of the fixing plate, the compressive stress of the structural concrete immediately below the fixing plate, and the compressive stress of the structural concrete around the load-bearing body, so that the use of the supporting plate becomes unnecessary. Then, as a result of the stress generated in the structure being averaged and dispersed, stable fixing for a long period of time against a large tensile force can be performed.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of an example of a fixing unit in which both ends of a ground anchor are fixed.

FIG. 2A is an enlarged vertical sectional view around a fixing hole showing an example of a head fixing portion, and FIG. 2B is a plan view of an example of a fixing plate used for fixing.

[Explanation of symbols]

1. Underground beams, 2. Cast-in-place concrete piles, 3A,
3B ... load-bearing body, 4 ... unbonded steel stranded wire, 4A ...
Sheath, 5 fixing plate, 6 template, 7
Wedges, 8 fixing holes, 9 support plates.

Claims (1)

(57) [Claims] 1. A load-bearing body (steel pipe) in which one unbonded steel stranded wire is inserted, embedded in the structural concrete so that the upper end surface is exposed to the upper surface of the structural concrete, and fixed thereon. A head anchor portion of a ground anchor where a fixing plate having holes is placed and tension is applied to the steel stranded wires penetrating through the fixing holes, and the ends of the steel stranded wires are fixed to the fixing holes by wedges.