JPH0314964B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an earth anchor that presses against an earth retaining wall buried in the ground to prevent the earth retaining wall from collapsing during excavation of earth and sand. More specifically, the present invention relates to an earth anchor extraction method for pulling out such an earth anchor from the ground.

[Prior Art] When earth retaining walls are supported by earth anchors, it is often necessary to remove the earth anchors after construction is completed due to problems such as underground rights.

By the way, in order to remove this earth anchor, conventionally the earth anchor must be pulled out with a pulling force greater than the strength of the anchor, or an instantaneous heat generating part must be provided in advance on the tensile steel part that is not covered with mortar, etc. The commonly used method was to cut it off and pull it out.

[Problems to be Solved by the Invention] However, the former method requires a powerful pulling jack and has the disadvantage that the work is not easy, and the latter method has the disadvantage that it is not possible to pull out all the tensile steel material. It was hot.

Therefore, in recent years, heating wires are buried in tensile steel materials and a heat-melting synthetic resin with adhesive properties is coated, and when the earth anchor is removed, the heating wires are energized to generate heat, melting the resin and making the tensile steel materials. It has been proposed to reduce the adhesion force between the steel and mortar and pull out the tensile steel.

According to this method, the above-mentioned drawbacks of the conventional drawing method are solved, but it takes time and effort to attach a heating wire to each tensile steel material that is used, and the number of conductors of the heating wire is large. There are drawbacks such as the fact that it becomes complicated to handle over time.

Furthermore, Japanese Patent Application Laid-Open No. 51-8714 discloses a technique for detonating explosives to destroy mortar and the like, thereby reducing the adhesion between the tensile steel and the mortar, and pulling out the tensile steel. However, according to this known technique, the explosion generates noise and vibration, and there are also restrictions on handling explosives.

For these, JP-A-55-165325, JP-A-Sho
No. 53-48306 and Japanese Patent Application Laid-open No. 52-134210 disclose a method of pulling up wave-broken metal to destroy the mortar, etc. at the anchor anchorage part, reducing the adhesion between the tensile steel and the mortar, and pulling out the tensile steel. The technique is shown. However, according to this known technique, since the broken metal has mortar or the like attached thereto, a strong pulling jack is required. During the period until the earth anchor is pulled out (depending on the construction work, it usually takes at least three months), the broken hardware will rust, making it difficult to pull up the hardware, and it will be uneconomical as one piece of broken hardware is required for each earth anchor. There are problems such as:

The object of the present invention is to provide a method for pulling out an earth anchor, which can easily destroy mortar and the like with a breaking metal and economically pull out all the tensile steel members.

[Means for Solving the Problem] The earth anchor pulling method of the present invention is an earth anchor pulling method for pulling out an earth anchor that is buried in the ground and presses against an earth retaining wall in order to prevent the earth retaining wall from collapsing. The earth anchor includes a core material, a plurality of tensile steel materials surrounding the core material, a first sleeve that covers the core material of the anchor fixing part, and a first sleeve that covers the tensile steel material of the anchor free part and that extends from the first sleeve. Using an earth anchor consisting of a second sleeve with a larger diameter and a plug filling the gap between the second sleeve and the first sleeve, pulling out the core material, and removing the tip and A step of press-fitting a broken metal object whose outer diameter at the base is approximately equal to the inner diameter of the first and second sleeves into the gap formed by pulling it into the core material, and forming the broken metal object into the anchor fixing part. A process of destroying the mortar etc. of the anchor fixing part by press-fitting it into the space where the anchor is anchored and reducing the adhesion force between the mortar etc. and the tensile steel material, and removing the tensile steel material whose adhesion force with the mortar etc. has decreased from the ground. It includes a pulling process.

[Function] According to the earth anchor extraction method of the present invention as described above, the earth anchor is inserted into the drilled hole,
Fill the hole with mortar, etc. By solidifying the filled mortar, etc., the tensile steel material of the anchor fixing portion and the ground are integrated.

The hole wall of the anchor free portion is held by solidified mortar or the like.

Furthermore, the tensile steel material in the free part of the anchor is protected from rainwater and moisture by the second sleeve, solidified mortar, and the like.

When pulling out the tensile steel material, the space between the tensile steel materials in the free part of the anchor obtained by pulling out the core material and the space in the second sleeve are used as guide holes, and the broken metal is press-fitted by applying an impact. By press-fitting this destructive metal, mortar etc. attached to the tensile steel material at the anchor fixing part is destroyed, the adhesion force between the tensile steel material and mortar etc. decreases, and it is possible to pull out all the tensile steel materials with a relatively small force. Become.

[Examples] Examples of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 shows a state in which the retaining wall 2 is pressed by the earth anchor 5. The anchor 5 pulls the tensile steel material 12 with a jack, and while the tensile steel material in the anchor free part B remains stretched, the nut or grip 6 Fix it with. In this way, the tensile steel material 12 that has been stretched will be forced to return to its original shape, causing the earth retaining wall 2 to
By pressing , it will play the role of retaining earth during excavation work. At this time, the anchor fixing part A is also pulled in the opposite direction, but this part has the adhesive force between the tensile steel material 12 and the mortar 4, and the mortar 4.
The adhesion force with the ground 1 acts to resist the tensile force.

In FIG. 1, 7 is a plate, 8 is a pedestal, 9 is a stand-up, and 10 is a bracket.

In Figure 1 A to C, earth anchor 5
consists of a core material 11 and a plurality of tensile steel members 12 surrounding the core material 11, and the core material 11 of the anchor fixing part A fixed with mortar is a first sleeve 1 with a small diameter.
The free part B of the anchor, which is covered by the anchor material 3 and which is not fixed with mortar, is covered with the core material 11 and the tensile steel material 12 together with a second sleeve 14 having a large diameter. A plug 15 is provided at the end of the large diameter sleeve 14 to prevent mortar etc. from flowing into the sleeve 14. In addition, the core material 11 and the tensile steel material 12 may be a steel rod or may be a wire-shaped steel wire.

As shown in FIG. 3, the earth anchor 5 having such a structure is inserted into the drilled hole 3, and the hole is filled with mortar or cement milk 4. The mission of the anchor is performed by integrating the earth anchor 5 with the ground 1 by hardening the filled mortar or cement milk 4. The anchor's mission is to use a tension jack and install it as shown in Figure 1 above. In this state, drill hole 3 in the free part of the anchor.
The hole walls are held by solidified mortar or the like 4 to prevent collapse. In addition, the second sleeve 1
The tensile steel inside 4 is protected from corrosion due to rainwater and moisture.

In this state, the core material 11 is subjected to compressive force against the plurality of tensile steel members 12 and the first sleeve 13, and the tensile steel members 12 and the first sleeve 13 are crushed toward the center of the sleeve. It has the effect of making sure that there is no such thing. That is, when the core material 11 fulfills its mission as an earth anchor, it functions as a spacer that resists compressive force.

Once the earth anchor has completed its mission after a predetermined period of time, the tension jack releases the load and removes the tension steel 12.

The removal procedure is as follows.

First, the core material 11 is pulled out from the first sleeve 13 and the second sleeve 14 as shown in FIG.
As a result of this drawing, a cylindrical second space S2 is formed in the second sleeve 14 by the plurality of tensile steel members 12, and a second space _S2 is formed in the first sleeve 13.
A first space S _{1 having a smaller diameter than S 2 is} formed. A harpoon-shaped breaking metal object 16 shown in FIGS. 5A and 5B is guided into this second space _S2 and inserted, for example, by a rod 17 as shown in FIG. The outer diameters of the tip and base of this broken metal object 16 are approximately equal to the inner diameters of the first and second spaces S ₁ and S ₂ , respectively.

Then, the rod 17 is pressed into the first space _S1 by applying an impact, for example, with a hammer. As a result, the mortar 4 is easily destroyed as shown in FIG. 6 (the state in which the mortar is destroyed is indicated by 4').
The tensile steel material 12 and the mortar 4 are separated. The separated tensile steel material 12 is pulled out using a jack 18 or by hand. In addition, instead of Rod 17, Destruction Hardware 1
A hose may be connected to 6 to apply water pressure to destroy the mortar 4.

[Effects of the Invention] Since the present invention is configured as described above, it is possible to destroy the mortar etc. attached to the tensile steel materials using the breaking metal, and to pull out all the plurality of tensile steel materials with a relatively small tensile force. .

Furthermore, unlike the conventional method, there is no need to bury a broken metal object, and one broken metal object is sufficient, so it is economical.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing a state in which earth retaining is being pressed by an earth anchor implementing the method of the present invention;
Figures 2A and 2B show one embodiment of the present invention, where A is a longitudinal cross-sectional view, B is a cross-sectional view of the anchor fixing part, Figure 3 is a vertical cross-sectional view showing the state in which the core material is pulled out, and Figure 4 The figure is a cross-sectional view showing the state in which the broken metal is press-fitted into the space created by pulling out the core material.
B shows the destroyed hardware, A is a side view, B is a front view,
FIG. 6 is a longitudinal sectional view showing a state in which the mortar is destroyed and the tensile steel material and mortar are separated. 1...Ground, 2...Earth retaining wall, 3...Drilling, 4...
...Mortar, 5...Earth anchor, 6...Nut, 7...Plate, 8...Pedestal, 9...Horizontal, 10...Bracket, 11...Core material, 12...
...Tensile steel material, 13...First sleeve, 14...
...Second sleeve, 15...Plug, 16...Destruction hardware, 17...Rod, 18...Judge.

Claims (1)

[Claims] 1. In an earth anchor extraction method for pulling out an earth anchor that is buried in the ground and presses against the earth retaining wall in order to prevent the earth retaining wall from collapsing, the earth anchor includes a core material and a plurality of earth anchors surrounding the core material. a tensile steel material, a first sleeve that covers the core material of the anchor fixing part, a second sleeve that covers the tensile steel material of the anchor free part and has a larger diameter than the first sleeve, and the second sleeve and the first sleeve. The step of pulling out the core material using an earth anchor consisting of a plug that fills the gap between the first and second sleeves, and the outer diameter of the tip and base portions being approximately equal to the inner diameters of the first and second sleeves, respectively. A process of press-fitting the same broken metal object into the space formed by pulling out the core material, and destroying the mortar etc. of the anchor anchor part by press-fitting the broken metal object into the space formed in the anchor anchor part. An earth anchor pulling method comprising the steps of: reducing the adhesion between the mortar, etc. and the tensile steel; and pulling out the tensile steel, whose adhesion to the mortar, etc. has been reduced, from the ground.