JPH07259087A - Ground anchor head fixation part - Google Patents

Abstract

PURPOSE:To provide a long-period stability against a large tensile force by inserting each unbond steel strand through a bearing body, burying the bearing body so that its top face is exposed at the oversurface of the concrete of a structure, allowing the steel strand to penetrate a fixing hole in a fixing plate placed on the bearing body, and fixing the end of the strand by a wedge while a tension is given to the strand. CONSTITUTION:A bearing body 3A is put as covering each of the unbond steel strands 4 which are buried in a cast-in-place concrete pile 2 and installed in a specified position on an underground beam 1 and underground beam concrete is placed. The top face of the underground beam 1 is finished so that the top face of the bearing body 3A buried at the oversurface of the beam 1 is positioned flush. Then the sheath at the end of each strand 4 is torn and pulled by a jack and a certain tension is given, and a wedge 7 is driven into a fixing hole 8 in a fixing plate 5, and thus the fixation is completed.

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 anchor portion of a ground anchor.

[0002]

2. Description of the Related Art As a head anchoring portion of a ground anchor, a pressure plate and a fixing plate are generally used, and an end of a PC steel stranded wire is fixed to a fixing hole of the fixing plate by a wedge through the pressure plate. Is.

[0003]

According to the conventional method, a PC is used.
The bending force of the bearing plate and the anchor plate and the compressive stress of the structural concrete immediately below resist the tension force introduced into the steel stranded wire, and both members must have high strength and a large cross section. The larger the size of an object, the greater the tendency, which leads to an increase in cost.

In addition, since the pressure bearing plate and the fixing plate become large when the anchor becomes large, it cannot be used for a large anchor at present.

[0005]

SUMMARY OF THE INVENTION According to the present invention, the structure of the anchor head anchoring portion is provided in which the load bearing body which is a steel pipe is used in the anchoring portion of the anchor head to disperse the stress, resulting in a large anchoring force. It is about.

That is, according to the present invention, a load-bearing body (steel pipe) having one unbonded steel stranded wire inserted therein is embedded in structural concrete so that its upper end surface is exposed to the upper surface of the structural concrete, A fixing plate with a fixing hole is placed on it, and while introducing tension to the steel stranded wire that penetrates the fixing hole, the head anchoring part of the ground anchor in which the end of the steel stranded wire is fixed to the fixing hole with a wedge Is.

According to the present invention, the bending force 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 are shared with the tension force introduced into the PC steel strand. Therefore, it becomes unnecessary to use a bearing plate having high strength and a large cross section. The fixing tool can be downsized to the same degree of tension as the conventional one, and the fixing tool having the same size as the conventional one can endure the larger tension. As a result, it can be used for large anchors that could not be used with conventional ones.

[0008]

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

FIG. 1 is a vertical cross-sectional view of an example of a fixing portion in which both ends of a ground anchor are fixed, and FIG. 2A is an enlarged vertical cross-sectional view of a fixing hole and its periphery showing an example of a head fixing portion. Figure 2
FIG. 6B is a plan view of an example of a fixing plate used for fixing.

In the example shown in FIG. 1, the cast-in-place concrete pile 2 also serves as a ground anchor body, on which the underground beam 1 is constructed, and the head of the ground anchor is fixed on the upper surface of the underground beam 1. There is.

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

(1) Each of the unbonded steel stranded wires 4 embedded in the cast-in-place concrete pile 2 has a load-bearing body 3A attached to each of them.
The underbeam girder 1 is placed with a reinforcing bar at a predetermined position on the undergirder, and the underground girder concrete is placed. It is preferable to change the length of the load-bearing body 3A to be covered one by one in order to widely disperse the compressive stress.

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

(3) The template 6 and the fixing plate 5 are placed while inserting the unbonded steel twisted wire 4 into each hole. The sheath 4A at the end of each unbonded steel stranded wire 4 is peeled off, and a predetermined tension is introduced by pulling with a jack to drive the wedge 7 into the fixing hole 8 of the fixing plate 5 to fix it.

(4) Although not shown, fixing is completed by performing necessary operations such as attaching a protective cover to the upper portion of the fixing plate 5 and enclosing rust preventive oil in the protective cover.

FIG. 2B shows an example of the fixing plate 5, in which a large number of fixing holes 8 are bored in a donut-shaped disc in a tapered manner. In this example, 24 fixing holes 8 are provided, but this number is appropriately determined. In extreme cases, only one is required. However, the fixing plate 5 having a large number of fixing holes 8
It is efficient to use.

Although a donut-shaped disc is shown in this example, it may be a donut-shaped disc having no hollow portion in the central portion, and any shape other than the disc may be used.

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

Since an example of the fixing unit on the () side is shown, it is not related to the present invention, but the description will be slightly supplemented.

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

A large number of holes are bored in the pressure bearing plate 9, and an unbonded steel stranded wire 4 with a sheath at the end is inserted into the hole for a pulling die in the hole, and another hole for a compression die is inserted. Has the end of the unbonded steel stranded wire 4 fixed thereto, and the load bearing member 3B is vertically fixed to the pressure bearing plate 9 in the compression die hole so as to cover the unbonded steel stranded wire 4 as in the present invention. .

In the tension type fixing portion of the ground anchor side fixing portion, not only the unbonded steel stranded wire 4 with the sheath at the end but also a deformed steel rod (not shown) or a PC steel material can be used. When a steel rod is used, it is connected to the unbonded steel stranded wire 4 by a connecting tool (not shown) above the fixing portion.

The use of the mixed type fixing unit as the ground anchor body side fixing unit is an example, and in the present invention, the system of the ground anchor body side fixing unit may be a tension type, a compression type or a mixed type.

[0024]

EFFECTS OF THE INVENTION Since the load bearing body is embedded in the structure so as to surround each PC steel stranded wire in the ground anchor anchoring portion on the structure side, the tension introduced into the PC steel stranded wire 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 are shared to resist the force, and it becomes unnecessary to use the bearing plate. Then, as a result of the stress generated in the structure being averaged and dispersed, it is possible to perform stable fixing for a long time against a large tensile force.

[Brief description of drawings]

FIG. 1 is a vertical cross-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 unit, and FIG. 2B is a plan view of an example of a fixing plate used for fixing.

[Explanation of symbols]

1 ... Underground beam, 2 ... cast-in-place concrete pile, 3A,
3B ... Load-bearing body, 4 ... Unbonded steel stranded wire, 4A ...
Sheath, 5 ... Fusing plate, 6 ... Template, 7 ...
Wedges, 8 ... fixing holes, 9 ... bearing plates.

Claims (1)

[Claims] 1. A load-bearing body (steel pipe) having a single unbonded steel stranded wire inserted therein is embedded in structural concrete so that the upper end surface thereof is exposed on the upper surface of the structural concrete, and is fixed thereon. A head anchoring part of the ground anchor in which a fixing plate with holes is placed and the end of the steel strand is fixed to the fixing hole with a wedge while introducing tension to the steel strand that penetrates the fixing hole.