JPS58110717A - Drawing of earth anchor - Google Patents

Abstract

PURPOSE:To draw out a tension steel member with small loads by packing a static breaking agent is into a sleeve at the fixed portion of an anchor through an aperature formed when pulling out a core material. CONSTITUTION:A core material 11 is pulled out of sleeves 13 and 14, and a slurried static breaking agent 16 is packed into the sleeve 13 at the fixed portion A of an anchor through the aperture formed when pulling out the core material 11. The static breaking agent 16 used is composed of a lime-based inorganic compound as a main component and an organic and inorganic compound and exerts an expansion pressure as a breaking force from its hydration reaction. The cement mortar 4 of the fixed portion A of the anchor is broken by the expansion pressure of the static breaking agent 16 and thereby the adhesion between a tension steel member 12 and the cement mortar 4 is weakened. The tension steel member 12 thus separated is drawn out with small loads, e.g., man power, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for pulling out an earth anchor that supports an earth retaining wall in which earth and sand are excavated.

If a retaining wall is supported with an earth anchor, it may be necessary to remove the earth anchor after the construction is completed due to issues such as underground rights.

By the way, conventional methods for removing the earth anchor include pulling out the earth anchor with a pulling force greater than the strength of the anchor, or placing an instantaneous heat generating part in advance in the tensile steel part that is not covered with mortar, etc. The method of cutting (7) pulling out at that part was generally adopted.

However, the former method has the disadvantage that it requires a powerful drawing jack and is not easy to work with, and their method has the disadvantage that it is not possible to pull out all the tensile steel material.

Therefore, in recent years, tensile steel piezoelectric hot wires have been coated with adhesive heat-melting synthetic materials and ground anchors. It has been proposed that during removal, electricity is applied to heating wires to generate heat, melting the resin and reducing the adhesion between the tensile steel and mortar, and then pulling out the tensile steel.

According to this method, the above-mentioned deficiencies of the conventional drawing method can be solved, but it is time-consuming because a heating wire must be attached to each tensile steel material that is used in large numbers, and the conductor of the heating wire is There are some issues, such as the large number of books, making handling them complicated.

Therefore, the purpose of the present invention is to solve the above-mentioned problem of the conventional method, and to solve the problem without requiring complicated work.
The object of the present invention is to provide a method for pulling out an earth anchor by which a portion of the tensile steel material can be pulled out while leaving only a portion of the tensile steel material.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of the earth anchor pulling method of the present invention will be described with reference to the drawings.

Figure m1 shows the state in which the earth anchor 5 is pressed against the earth retaining member 112, and the anchor is jacked up to the tensile steel member 1.
↓, and fix it with a nut or grip 6 while keeping the tensile steel material of the free part B of the anchor stretched. This will result in an extended pull, which will serve as earth retaining during the excavation process. At this time, the anchor fixed part M is also pulled in the opposite direction, but this part is pulled by the adhesion force between the tensile steel l↓ and the mortar 4, and the adhesion force between the mortar 4 and ±1. is resisting.

In addition, regarding FIG. 1, 7 indicates a grade, 8 indicates a stand piece, 9 indicates a return, and IO indicates a bracket.

Therefore, if either of the above-mentioned adhesion forces decreases, the anchor will lose the balance of forces and fall through. By using this principle, it has been used as an earth anchor, reducing the force of force between the tensile steel and mortar, and making it possible to pull out the tensile steel with a small load. It is an invention.

The construction of the anchor is the same as the conventional earth anchor construction method.
, the hole is drilled to a predetermined depth using a hole drilling machine. A tensile material having the configuration shown in Figure 2 A1 and C is inserted into the drilled hole.

The tensile material consists of a core material 11 and a large number of tensile steel materials 12 surrounding the core material 11, and at least the core material 11 of the anchor fixed part A fixed with mortar is covered with a sleeve 13, and the core material 11 is covered with a sleeve 13 and The anchor free portion B, which is not anchored, is covered with a large-diameter sleeve 14 together with the core material 11 and the tensile steel material 12. A plug 15 is provided at the end of the large diameter sleeve 14 to prevent mortar etc. from flowing into the sleeve 14. Note that the core material 11 and the tensile steel material 12 may be a steel rod or a steel wire shaped into a wire.

A tensile member 5 having such a structure is shown in Fig. 3.
11 Insert into the hole 3 and fill the inside of the hole with mortar or cement milk 4. The mission of the anchor is accomplished by the hardening of the filled mortar or cement milk 4, which integrates the tensile material 5 with the ground l.

The anchor's mission is to perform the VCat as shown in Figure 1 above. Complete the anchor mission,
The load is released using a tension jack and the tension steel 12f is removed.

The removal procedure is as follows.

First, the core material 11 is pulled out from the sleeves 13 and 14. As shown in Figure 3, a slurry-like static crushing agent 16 enters the sleeve 13 of the anchor fixed portion A through the gap where the core material is pulled out. Static sand crushing agents are mainly composed of lime-based inorganic compounds, to which organic and inorganic compounds are added.
This is a conventionally known device. After interposition, the crushing effect is achieved within 10 to 20 hours, and as shown in Fig. 4, the mortar in the anchor fixed part A is destroyed (the state in which the mortar is destroyed is indicated by 4'), and the tensile steel material is 12 and mortar 4' are separated. The separated tensile steel material 12 is pulled out using a jack 17 or by hand.

As explained above, according to the method for pulling out an earth anchor according to the present invention, there is no need for a pulling jack with a force of 4/# as in the conventional method, and the entire tensile steel material can be pulled out. In addition, since it is used as a static crushing agent, there is no vibration or noise.Furthermore, it can be used to melt resin applied to tensile steel materials using electric heating at, and to melt the resin applied to tensile steel materials. It does not require any troublesome work such as installation.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a state in which the earth anchor is pressed against the ground. 2A and 2C show the tensile material used in the present invention, A is a longitudinal cross-sectional view, C is a cross-sectional view of the fixed portion of the anchor, and C is a cross-sectional view of the free portion of the anchor. FIG. 3 is a longitudinal cross-sectional view showing the state in which the core material is drawn out and subjected to static crushing. FIG. 4 is a longitudinal sectional view showing a state in which the mortar is destroyed and the tensile steel material and the mortar are separated. l...Ground 2...Earth retaining 3...Drilling 4...
・Mortar 5...Tension material 6...Nut 7...Plate 8...Pedestal 9...
Restored 10... Bracket ] 1... Core 44
12...Tensile steel material 13...Sleeve
14... Sleeve 15... i & 16... Static crushing agent 17... Jatsuki Patented by 1 person Chemical Grout Co., Ltd., 43\ Representative Patent Attorney Takashi Takayoshi ``\゛tsu)~,
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Claims (1)

[Claims] In order to prevent earth retaining walls from collapsing when excavating earth and sand, etc., a method of pulling out earth anchors that are installed in the ground and pressed against earth retaining walls uses a core material as an earth anchor and a large number of tensile forces surrounding it. The core of the fixed part of the anchor, which is made of steel and is fixed with at least mortar, etc.
The material is covered with a sleeve, and the core material and tensile steel material in the free part of the anchor that is not fixed with mortar etc. are covered with a sleeve. When removing the earth anchor, first pull out the core material. Next, a static crushing agent is filled into the sleeve of the anchor fixed part through the gap formed by pulling out the core material, and the static crushing agent expands and the expansion pressure causes the anchor fixed part to break. A method for pulling out an earth anchor, which is characterized by destroying mortar, etc. to reduce the adhesion between the tensile steel and the mortar, and thereby pulling the tensile steel from the ground.