JPH0733661B2 - anchor - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an anchor, and more particularly to an anchor that is less likely to be damaged and has a large yield strength.

[0002]

2. Description of the Related Art Conventionally, an anchor as shown in FIG. 4 has been adopted. That is, an anchor tension material a such as a PC strand is fixed to one end of a cylindrical anchor trunk body b, and this anchor trunk body b is inserted into a drilled hole c and filled with a grout hardening material d. In this case, the anchor trunk b for fixing the tensile member a was integrated as a whole, and the tensile force applied to the tensile member a became a compressive force and acted on the anchor trunk b. Therefore, such an anchor is called a compression type anchor.

[0003]

When the anchor trunk body b in which the portion for fixing the tensile member a and the cylindrical portion for preventing the damage of the hardened member d are integrated, the tensile force applied to the tensile member a is increased. The force acts as a compressive force on the tubular portion, and the trunk body of this type is designed to fully expect the tubular portion to share the compressive force. However, although the portion of the anchor trunk b to which the tensile member a is fixed is thick and strong, if the tubular portion is made too thick, the overall weight will be significantly heavy, so this tubular portion cannot be made too thick. When a large tensile force is applied to the conventional integrated anchor trunk b, the thin cylindrical portion loses this load to cause buckling, which may cause damage.

When the anchor trunk b is damaged in this way,
The hardened material d inside or around the cylindrical portion will collapse, and eventually the hardened material d that receives the tensile force applied to the tensile material a will be destroyed, and it will not be possible to receive the load, and the reliability as an anchor It was damaging.

The present invention has been made to solve the above problems, and an object thereof is to provide an anchor which is not damaged and has high reliability.

[0006]

An anchor according to the present invention is an anchor trunk body in which a bearing portion for fixing a tension member and a hoop tension portion which is a tubular body are separately provided. The hoop tension portion is a tubular body formed of, for example, a steel pipe or casting. The inner surface of the hoop tension part is a straight surface with no irregularities. The bearing portion is also made of steel, casting, or the like, and has a plurality of holes for passing the tensile member. The bearing portion has an outer shape smaller than the inner diameter of the hoop tension portion, and is freely movable in the hoop tension portion. The bearing portion has a thick plate shape for fixing the tension member, and the hoop tension portion has a thinner wall thickness compared to this, which facilitates transportation and construction.

When a tensile force is applied to the tensile material, the hardened material is compressed, but the inner peripheral surface of the hoop tension portion is a straight surface, allowing the hardened material to shrink, and the hoop tension portion is continuously contracted. Never move. As the hardened material contracts, only the pressure bearing portion moves in the hoop tension portion, and the compressive force does not act on the hoop tension portion. The hoop tension portion exerts a restraining effect to restrain the hardened material inside and prevent the hardened material from being broken. In other words, the hardened material that transmits tensile force from the bearing portion does not collapse and can be used as a stable anchor.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below based on an embodiment shown in the drawings. In the figure, reference numeral 1 denotes an anchor trunk, which is a cylindrical hoop tension portion 2 and a disc-shaped bearing portion 3.
Is made up of. Both the hoop tension portion 2 and the bearing portion 3 are made of steel. The inner peripheral surface of the hoop tension portion 2 is formed as a straight surface having no unevenness. The outer diameter of the bearing portion 3 is formed slightly smaller than the inner diameter of the hoop tension portion 2, and a plurality of tension material insertion holes 4 are opened. A tensile member 5 such as a stranded wire is passed through the tensile member insertion hole 4 and fixed by a compression grip 6. The tensile member 5 is passed through an unbonded sheath 7 such as polyethylene.

The pressure bearing portion 3 is arranged in one end of the hoop tension portion 2, and a gap between the two is filled by the caulking 8 and is temporarily fixed. In this state, the anchor trunk body 1 is filled with the hardening material 9 to integrate them.

In this state, the anchor trunk 1 is placed in the drilled hole 10.
And place it at the bottom of the hole. A hardening material 11 such as a grout material is injected into the drilled hole 10 and hardened. When a tensile force is applied to this anchor, the hardener 9 contracts due to the compressive force, but the inner peripheral surface of the hoop tension portion 2 is formed straight, and the hardener 11 is cut off from the hoop tension portion 2. Since it moves freely inside this, no compressive force acts on the hoop tension portion 2. However, the hoop tension part 2 prevents the hardened material 9 inside from being restrained and destroyed. Since the compressive strength of the hardened material 9 is significantly increased by this restraining force, the bearing pressure is maintained and the anchor has a large proof stress.

The present invention can be applied not only to the compression type anchor described above, but also to a semi-bond type anchor as shown in FIG. The semi-bond type anchor does not pass the entire length of the tensile member 5 through the unbonded sheath 7, but attaches and fixes about 100 cm near the bearing portion 3 to the hardened material 9 in the hoop tension portion 2. In the case of such an anchor, since the attachment length is short, the adhesion may be broken between the hardened material 9 and the tensile material 5 due to the tensile force. Even in the case of such adherence breakage, the pulling force acts on the pressure bearing portion 3, but the hardening material 9 that has received the compressive force by the restraining force of the hoop tension portion 2 is restrained to prevent breakage.

[0012]

The present invention has the above-mentioned structure and can obtain the following effects. Since the hoop tension part and the bearing part of the anchor trunk are separated and the inner peripheral surface of the hoop tension part is a straight surface that can be cut with the hardened material, the compressive force generated by the tensile force acts only on the hardened material. It does not act on the hoop tension part and does not damage the hoop tension part.
Since the hoop tension part exerts only the restraining effect, the possibility of breakage is significantly reduced, making it a highly reliable anchor. The hoop tension portion restrains the hardened material on the inner side, so that the bearing portion transmits the load and prevents the hardened material from being broken. Since the hardened material does not break, it becomes a highly reliable anchor that can withstand a large load. In the experiment, it was decided that the yield strength was improved three times or more as compared with the conventional compression anchor. Since the bearing portion is thick and the hoop tension portion is relatively thin, the overall weight is light and the transportation and construction work is easy.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view of an anchor according to the present invention.

FIG. 2 is a cross-sectional view of a state in which a tensile force is applied.

FIG. 3 is a sectional view of another embodiment.

FIG. 4 is a cross-sectional view showing the entire anchor.

FIG. 5 is a cross-sectional view of a conventional anchor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Anchor trunk 2 Hoop tension part 3 Bearing part 5 Tensile material 6 Compression grip 7 Unbonded sheath 8 Caulking 9 Hardening material 10 Drilling hole 11 Hardening material

Claims (1)

[Claims] 1. In an anchor in which a proximal end of a tensile member is fixed to an anchor trunk body and is inserted into a drilled hole and a hardening material is filled in the drilled hole, the anchor trunk body is a thick support for fixing the tensile member. The pressure portion and the hoop tension portion, which is a relatively thin wall and at least the inner peripheral surface is a straight tubular body, the pressure bearing portion is smaller than the diameter of the hoop tension portion, and the pressure bearing portion is inside the hoop tension portion. An anchor characterized by being movable.