JPH02101219A - Construction method for oblique ground anchor - Google Patents

Abstract

PURPOSE:To remove the bending of a tension part by filling a gap between the tension part and an anchoring part with a packer, by injecting a grout in the anchoring part as well as a delaying grout in the tension part, and by giving tensile force to a tension material before the hardening of the delaying grout occurs. CONSTITUTION:A tension material 1 for ground anchoring is partitioned into an anchoring part 2 and a tension part 3 by a packer 4. A grout 6 is injected in the anchoring part 2, as well as a delaying grout 8 in the tension part 3. A little tensile force is given to the tension material 1 before the grout or the delaying grout 8 are hardened. The tension part is not to be installed in the grout in a curve. Damage to a grout material in stretching can thus be prevented.

Description

[Detailed description of the invention] [Industrial application field] This invention is a countermeasure against uneven earth pressure for buildings standing on sloped areas.

Prevents retaining walls from falling and reduces earth pressure acting on underground walls.

This paper relates to methods for constructing diagonal ground anchors used to stabilize slopes and increase the horizontal resistance of piles.

[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 part that has the role of transmitting tensile force to this anchor body. .

Conventionally, when installing this tension material diagonally,
The tension material in the anchor body formed by hardening the grout is installed in a straight line at the center of the anchor body by the spacer, but in the tension part, it is installed in the grout in a curved shape.

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 reliably install the grout material as an anchor at the tensile part after the grout has hardened, without causing injury or cutting of the unbonded sheath. The purpose of the present invention is to provide a construction method for diagonal ground anchors.

[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 seals between the tension part of the drilled hole and the anchor body, and injects grout that will become the anchor body, and then into the borehole around the tension part of the tension material, that is, in the upper part of the packer, A grout with a retardant composition is injected, and then the grout serving as the anchor body hardens, and a small tension force is applied to the tension material before the retardant 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 separated from the grout in the anchor body by the packer and becomes a different retarded grout. Because it is made of aluminum, it is not hardened, and the bending of the tension part of the tension material can be removed.

〔Example〕

The construction method of the present invention will be explained below with reference to illustrated embodiments.

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. Also, the tensile material 1 of the ground anchor
In order to inject the grout that will become the anchor body 2 around the lower end fixing part, a hole is drilled with a packer 4 attached to the lower end of the tension part 3 that transmits the tension force to the anchor body 2, as shown in FIG. Seal tightly.

Next, a fourth
Grout 6 is injected as shown in the figure. 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 the grout is injected into the anchor body, there is a step of enlarging the packer 4 in order to seal the 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 has a structure that can be expanded by inflating it by injecting grout into the inside from the grout pipe 9 shown in FIG.

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, above the packer 4, and the casing 5 is pulled out. Originally, the tension part could be hollow, but since there is a possibility of it collapsing, grouting (secondary injection) is used as a countermeasure.

After that, the grout 6 in the part that will become the anchor body 2 hardens.
Before the retarded grout 8 around the tension section 3 hardens,
A small tension force (temporary tension) is applied to the tensile material 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 has hardened, the tension member I is fully tensioned.

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

(Effects of the Invention) The method for constructing a diagonal ground anchor of the present invention is to install a tension member for the ground anchor in a hole in the ground, and then connect the tension member and the anchor body around the lower end fixing part of the tension member. A packer is provided at the boundary of the tension member, the backer separates and seals between the tension part of the drilled hole and the anchor body, grout is injected into the part that will form the anchor body, and then the tension part of the tension material is A grout with a retardant formulation is injected around the periphery, that is, at the top of the packer, and then the grout serving as the anchor body hardens, and before the retardant grout around the tension part hardens, a small ink is added to the tension member. It is characterized by giving tension.

According to this method, 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 separated from the grout in the anchor body by the packer, and a separate delay is applied. Since it is a flexible material, it is not hardened and can eliminate bending of the tensile part of the tension material.

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... Tension material, 2... Anchor body, 3... Tension part, 4... Backer 5... Casing, 6...
- Grout, 7... Grout pipe, 8... Delayed grout, 9... Grout pipe. Figure 1

Claims (1)

[Claims] A method for constructing a ground anchor buried obliquely in the ground, comprising: installing a tensile material for the ground anchor in a hole in the ground; , a packer provided to form a boundary between the tensioning part of the tensioning material and the anchor body, which seals between the tensioning part of the tensioning material of the drilled hole and the anchor body, and grouting the anchor body. Next, a grout with a retardant composition is injected around the tensile part of the tensile material, that is, in the upper part of the packer, and then the grout that becomes the anchor body hardens, and the grout around the tension part becomes retarded. 1. A method for constructing a diagonal ground anchor, characterized in that, before the grout hardens, a small tension force is applied to the tensioning material so that the tensioning material in the tensioning portion can be arranged in a straight line.