JPH0559218B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention is useful for countering uneven earth pressure in buildings standing on slopes, preventing retaining walls from falling, reducing earth pressure acting on underground walls, stabilizing slopes, and piles. This article relates to the construction method of diagonal ground anchors used to increase the horizontal resistance of soil.

[Prior art and problems to be solved by this invention]

This type of ground anchor tension member consists of an anchor body that is expected to be anchored to the ground, and a tension portion that has the role of transmitting tensile force to the anchor body.

Conventionally, when this tensile material is installed diagonally, the tensile material in the anchor body made of hardened grout is installed in a straight line at the center of the anchor body by a spacer, but in the tension part, the grout has a curved shape. It will be installed in

When installed in this manner, if the grout is tensed after it hardens, the tension material in the tension section will act to straighten the grout material, causing damage to the grout material. Furthermore, if an unbonded cable is used as the tensioning material, there is a risk that the unbonded sheath will be cut, resulting in a rust prevention problem.

This invention was devised in view of the above-mentioned circumstances, and its purpose is to ensure that it can be installed as an anchor without causing damage to the grout at the tensile part and cutting of the unbonded sheath after the grout has hardened. The object of the present invention is to provide a construction method for a diagonal ground anchor.

[Means to solve the problem]

According to this invention, the construction of a ground anchor to be buried diagonally in the ground is carried out by installing a tensile material for the ground anchor in a hole in the ground, and then installing a tensile material at the lower end of the ground anchor to transmit the tensile force. A packer is used to seal the space between the tensile part of the drilled hole and the anchor body, and inject grout that will become the anchor body, and then into the drilled hole around the tension part of the tensile material, that is, in the upper part of the packer. A grout with a delayed growth composition is injected, and then the grout serving as the anchor body hardens, and a small tension is applied to the tension member before the retarded grout around the tension part hardens. .

After the grout in the anchor body has hardened, by applying a small tension force to the tension member, at this point the grout around the tension member is distinguished from the grout in the anchor body by the packer and becomes a different delayed type. Because the material is hardened, it is possible to remove the bending of the tensile part of the tensile material. After curing of the retarded grout, the main tensioning of the tensile material is then carried out.

〔Example〕

The construction method of the present invention will be explained below with reference to illustrative examples.

First, the tension member 1 used as a ground anchor in the construction method of the present invention has an anchor body 2 having a bearing pressure portion at its tip as shown in FIG. 6, and a tension member 3 that transmits tensile force to the anchor body 2. , and a packer 4 provided between the tension portion 3 and the anchor body 2.

When constructing a ground anchor diagonally buried in the ground using this tensile material 1, a hole is first drilled in the ground in order to install the tensile material 1 as shown in FIG. At this time, since the ground on which the diagonal anchor is to be constructed is often relatively soft, it is necessary to drill holes using the casing 5.

Next, after drilling is completed, the tensile material 1 is installed inside the casing 5 as shown in FIG. In addition, in order to inject grout that will become the anchor body 2 around the lower end fixing part of the tension member 1 of the ground anchor, a third
As shown in the figure, a puller 4 is attached to the lower end of the tensioning part 3 that transmits tension to the anchor body 2.
Seal the borehole with.

Next, grout 6 is injected into the portion forming the sealed anchor body 2, as shown in FIG. The grout to be used as the anchor body is injected using the grout pipe 7 (see FIG. 6) after the casing 5 is pulled up to a position that will be the upper end of the anchor body. The casing 5 is pulled up here because the ground on which the anchor body is fixed is expected to have strength, and the ground is hard, and the hole wall is difficult to collapse even without casing.

Note that before injecting grout to serve as the anchor body, there is a step of enlarging the packer 4 in order to seal the drilled hole. Here, the packer 4 has the role of covering the hole in the upper part of the anchor body in order to apply pressure to the grout forming the anchor body. It has a bag-like shape made of rubber or cloth, and a grout pipe 9 shown in FIG.
It has a structure that can be expanded by inflating it by injecting grout.

Next, a grout 8 having a retardant composition as shown in FIG. 5 is injected around the tensile portion 3 of the tensile member 1, that is, into the upper part of the packer 4, and the casing 5 is pulled out. Originally, the tension part could be hollow, but
Since there is a possibility of collapse, grouting (secondary injection) is used as a countermeasure.

Thereafter, the grout 6 in the portion that will become the anchor body 2 hardens, and before the delayed grout 8 around the tension part 3 hardens, a small tension force (temporary tension) is applied to the tension member 1.

In this way, since the grout around the tension part 3 has not hardened at this point, the bend in the tension part 3 can be removed.

Then, after the delayed grout around the tension portion 3 hardens, the tension material 1 is fully tensioned.

In this way, the construction of the ground anchor, which is buried diagonally in the ground, is completed.

〔Effect of the invention〕

The construction method of the diagonal ground anchor of this invention is to install a tensile material for the ground anchor in a hole in the ground, and then install a tension material for the ground anchor at a position around the lower end fixing part of the tension material, which is the boundary between the tension part and the anchor body. A packer is provided in the hole, and the packer separates and seals between the tensile part of the drilled hole and the anchor body, grout is injected into the part that will form the anchor body, and then the area around the tension part of the tension material, that is, the packer Injecting grout with a retardant composition into the upper part of the tension member, after which the grout serving as the anchor body hardens, and before the retardant grout around the tension part hardens, a small tension force is applied to the tension member. It is characterized by

According to this method, after the grout of the anchor body has hardened, by applying a small tension force to the tension member, at this point, the grout around the tension member is distinguished from the grout of the anchor body by the packer, and has a different delay. Since it is a flexible material, it is not hardened and can eliminate bending in the tension part of the tension material.

Then, after the retarded grout has hardened, the tensile material is fully tensioned, so that the dilut injection operation can be carried out continuously.

This prevents the tension part of the tension material from being installed in a curved shape in the grout, and prevents damage to the grout material due to the tension material in the tension part trying to straighten due to the main tension after the grout hardens. When an unbonded cable is used as a tension member, it is possible to prevent problems in terms of rust prevention due to cutting of the unbonded sheath.

[Brief explanation of the drawing]

1 to 5 are process diagrams showing the method of constructing a diagonal ground anchor according to the method of this invention, and FIG. 6 is a front view showing a tension member used in the method of this invention. DESCRIPTION OF SYMBOLS 1... Tensile material, 2... Anchor body, 3... Tensile part, 4... Packer, 5... Casing, 6
... grout, 7 ... grout pipe, 8 ... delayed grout, 9 ... grout pipe.

Claims (1)

[Claims] 1. A construction method for a ground anchor that is buried obliquely in the ground, in which a tensile material for the ground anchor is installed in a hole in the ground, and then the tensile material is installed around the lower end fixing part of the tensile material. A packer provided to form a boundary between the tension part and the anchor body seals the space between the tension part and the anchor body in the tension material of the drilled hole, and injects grout that will become the anchor body, and then A grout with a retardant composition is injected around the tension part of the tension member, and then the grout that becomes the anchor body hardens, and before the retardant grout around the tension part hardens, a small ink is injected into the tension member. A method for constructing a diagonal ground anchor, characterized by arranging tension members in a tension part in a straight line by applying tension, and applying full tension to the tension members after hardening of delayed grout.