JPH04143312A - Anchor removing method - Google Patents

Abstract

PURPOSE:To certainly and smoothly perform the extraction of a tension member by receiving exothermic agents on both sides of a holding tool for fixing the top end of a tension steel material to a support pressure member, and heating and deteriorating the pressure adhering part between the holding tool and the tension steel material. CONSTITUTION:A firing body 9 is electrified from the outside of a hole and fired to fire an exothermic agent 7 in receiving chambers 61 and 64. Consequently, an anchor head 6, a cone 8 and the steel wire 21 of a tension steel member 2 are heated to a high temperature (about 1000-2000 deg.C). Then, the bore of the tapered hole of the anchor head 6 is slightly increased by the heating to allow an increase in diameter of the divided cone 8. The pressure adhering surface between the cone 8 and the steel wire 21 becomes soft and brittle by the heating. When the base end of the tension steel material 2 is pulled, a shear fracture is caused in the surface layer part of the steel wire 21 and the mountain part of the pressure adhering surface of the cone 8. Thus, the tension steel material 2 can be removed with a small pulling force.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a removal anchor method for removing tensile steel by chemical removal means.

・'Prior art> Removal anchor construction methods are broadly divided into mechanical methods and chemical methods, depending on the means of removing the tensile steel material.

The former method involves attaching a load-bearing body to the point where the unbonded tension material is folded back, releasing one of the bow tension materials exposed on the ground surface, and pulling the other.

The latter method is further divided into an explosion method and a heat generation method.

The blasting method is a method in which an explosive device is attached to the free length of the tensile steel material, and the tensile steel material is ruptured by blasting when it is removed.

The method of generating heat is to insert the tip of the tensile steel material through the bearing plate and fix it by caulking it with a grip, as well as placing a heat generating agent in the front of the grip, which softens the grip due to the heat generated and pulls out the tensile steel material. .

<Problems to be Solved by the Present Invention> The conventional anchor removal techniques described above have the following problems.

〉 In the method of mechanical removal, a large tensile strength is fJ! In addition to being difficult, the tensile steel material is forcibly bent, which causes the strands to come apart, and the antirust oil to scatter, making removal work difficult.

Furthermore, when assembling the anchor, it is difficult to set the free lengths of the folded tension members to be equal.

Therefore, as the difference in the free lengths of the folded tensile materials increases, there is a risk that an excessive tensile force will be applied to the shorter tensile material during fixation, causing it to break.

In the case of the blasting method, tensile steel remains in the anchorage, which becomes an obstacle to subsequent work such as press-fitting sheet piles.

<C> In the case of the heating method, it is difficult to sufficiently soften the crimp surface of the grip that comes into contact with the tensile steel material.

Therefore, excessive force may be required to remove the tensile material, or the tensile material may break midway and become unrecoverable.

Compressive force acts on the solidified material that makes up the anchor length, so
If the surrounding ground is soft, the consolidated material is likely to cause buckling failure.

Therefore, the anchor strength depends on the anchorage ground.

<Purpose of the present invention> The present invention has been made to solve the above problems, and its purpose is to provide a removal anchor construction method that enables reliable and smooth removal of tension members. It's about doing.

A further object of the present invention is to provide a removal anchor construction method that can effectively prevent buckling failure of the anchoring portion and increase the anchor strength.

In other words, the present invention fixes the tip of a tensile steel material to a bearing member via a gripping tool, and softens the gripping tool by heat generation from a heat-generating agent sealed in the tip of the tensile steel material. The removal anchor method for removing tensile steel is characterized in that a heat generating agent is contained in both sides of the gripping tool, and the crimped portion between the gripping tool and the tensile steel is heated and deteriorated to remove the tensile steel.

Description of the present invention> The present invention will be described below with reference to the drawings.

<A> Constituent members of the removal anchor FIG. 1 shows a sectional view of the fixed length portion of the removal anchor according to the present invention, and FIG. 2 shows an assembled view of the removal anchor excluding the tension member.

1 is an anchor hole, 2 is a tensile steel material, 3 is a reinforcing bar cage into which the tensile steel material 2 is inserted, 4 is a consolidation material injected over the range of the anchoring length of the anchor hole 1, and 5 is a tensile material in front of the reinforcing bar cage 3. The load-bearing body into which the steel material 2 is inserted is an anchor head 6 that fixes the end of the tensile steel material 2 in front of the load-bearing body 5.

Each component will be explained below.

Exit> Tensile steel material The tensile steel material 2 can be a known unbonded type tensile steel material in which an m-wire 21 such as a PCM wire is coated with a sheath 22.

At the fixing portion at the tip of the tensile steel material 2, the sheath 21 is cut off over a certain length to expose the steel wire 21.

Kuha〉Reinforcing bar basket The reinforcing bar basket 3 has tie bars 31 arranged at equal intervals, and the ties 31
It consists of a straight main reinforcing bar 32 that intersects with 7, and is designed to prevent buckling failure of the consolidating material 4 constituting the anchor length section.

Therefore, if the surrounding ground is hard, it may be omitted.

<2> Load-bearing body The load-bearing body 5 is a columnar body that exhibits the function of reinforcing the anchor strength, and has a hole 51 for insertion of the tensile steel material 2 parallel to its axis, and a plurality of annular grooves 52 on its circumferential surface. has.

In this example, a case will be described in which two sets of load-bearing bodies 5 are arranged, but the number of the load-bearing bodies 5 to be installed is determined as appropriate depending on the desired anchor strength.

(E) The anchor head 6 is a steel anchor head for fixing the tip of the tensile steel material 2, and is provided with a recessed storage chamber 61 for enclosing the heat generating material 7, which is sealed with a lid 62.

The anchor head 6 has a plurality of tapered holes 6 passing through both sides.
3 have been established.

A storage chamber 64 for enclosing the heat generating material 7 is recessed on the small diameter side of the tapered hole 63, and leakage of the heat generating material 7 is prevented by an annular sealing material 65 provided at the outlet of the storage chamber 64.

Further, each tapered hole 63 accommodates a plurality of vertically divided cones 8 .

In the present invention, each tapered hole 63 has a storage chamber 61 on both sides.
64, and is configured such that the heat generating material 7 can be accommodated on both sides of each cone 8.

Reference numeral 66 in FIG. 1 is a cone pressing spring, which is fixed to the lid 62 side.

<F> Cone In the present invention, in order to enhance the removal effect of the tensile steel material 2, the following considerations were added to the cone 8.

That is, as shown in an enlarged view in FIG. 3, the entire surface of the crimping surface of the tensile steel material 2 that is crimped with the steel wire 21 is provided with grooves 81 in a spiral shape or in a ring shape at regular intervals in a direction intersecting the tensile direction.
are recessed, and a peak portion 82 is formed between the grooves 81 .

Thereby, the heat generated by the heat generating material 7 is evenly transmitted to each mountain portion 82.

Furthermore, the structure of the surface layer of the crimp surface of the cone 8 is configured to exhibit brittleness when the heat generating material 7 generates heat.

In order to exhibit brittleness, the surface hardness (Pickus hardness) is finished to about Hv 100 to 150 by, for example, performing charcoal quenching treatment.

More preferably, the tensile steel material 2 is also subjected to a punching treatment or the like to have a surface hardness of about Hv500.

By doing this, a reliable gripping force can be exerted between the tensile material 2 and the cone 8 during fixation at room temperature, and when heated to 500°C or higher, the structure of the tensile material 2 and the cone 8 will soften. Shear failure will occur.

<G> Ignition means As the exothermic agent 7, a known exothermic agent can be used.

Further, as a means for igniting the exothermic agent 7, an electric type igniter 9 as shown in FIG.
It is possible to employ a known ignition means that ignites by supplying power to the lead wire 91 connected to.

In addition, depending on the type of exothermic agent 7, it is also possible to adopt a method of igniting by chemical reaction or igniting by adding water.

Further, the igniter 9 may also be provided in the storage chamber 64.

<Effect> Next, the construction method will be explained.

<A> Fixing operation (Fig. 1.2) Outside the hole, each tensile member 2 is inserted into the reinforcing bar cage 3 and the load-bearing body 5, and its tip is fixed to the anchor head 6 with the cone 8 to assemble the anchor.

At this time, the heating agent 7 is sealed in each of the storage chambers 61 and 64.

After inserting the assembled anchor into the anchor hole 1, a consolidation material 4 such as mortar or concrete is injected into the anchor hole 1.

Waiting for the solidifying material 4 to harden, the tensile steel material 2 outside the hole (not shown) is
and fix using a known fixing tool.

<Opening> Removal Operation (Fig. 1.3) Electricity is applied from outside the hole to ignite the ignition body 9, and each exothermic agent 7 sealed in the storage chambers 61 and 64 is ignited.

As a result, the anchor head 6, the cone 7, and the steel wire 21 of the tensile steel material 2 are heated at a high temperature (approximately 1000°C to 2000°C).

By heating, the diameter of the tapered hole 81 of the anchor head 6 becomes slightly larger, allowing the divided cone 8 to expand in diameter.

Furthermore, as shown in FIG. 3, the crimped surfaces of the cone 8 and the steel wire 21 become soft and brittle due to heating.

When the base end of the tensile steel material 2 exposed outside the hole is pulled in this state, the surface layer of the steel wire 21 and the crest 82 of the crimping surface of the cone 8 cause shear failure, and the tensile steel material 2 can be removed with a small extraction force. .

<Other Examples> Instead of the cone 8, a caulking grip may be used.

In the case of this embodiment, storage chambers are formed on both sides of the caulking grip, and heating is applied from both sides of the caulking grip to soften the crimp surface of the grip, as in the above-described embodiment.

Effects of the Present Invention> Since the present invention is as explained above, the following effects can be obtained.

<B> Since the three members of the anchor head, cone, and tensile steel material can be effectively heated to soften the structure, the tensile steel material can be extracted reliably and smoothly.

<C> When a load-bearing body is used in combination with the anchor head, the unevenness of the side surface and circumference of the load-bearing body on the outside of the hole becomes a resistance surface, increasing the anchor strength. <C> When used in combination with a reinforcing bar cage, the surrounding It is possible to restrain the deformation of the solidified material that makes up the anchorage length without being affected by the properties of the ground.

Therefore, buckling failure of the anchorage length can be prevented even if the surrounding ground is soft.

[Brief explanation of the drawing]

Figure 1 - An explanatory diagram of the removal anchor construction method according to the present invention, a sectional view of the anchoring length Figure 2 An assembled diagram of the anchor Figure 3: Enlarged view of the gripping part of the tensile steel material

Claims (3)

[Claims] (1) In the removal anchor method, the tip of the tensile steel material is fixed to the bearing member via a gripping tool, and the gripping tool is softened by heat generated by a heat-generating agent sealed in the tip of the tensile steel material to remove the tensile steel material. A removal anchor construction method characterized by storing a heat generating agent on both sides of the tool and heating and softening the crimped portion between the gripping tool and the tensile steel material to remove the tensile steel material. (2) The removal anchor construction method according to claim (1), characterized in that a load-bearing member having a through hole for passing a tensile steel material is fixed to the proximal surface of the bearing pressure member in contact with the surface thereof. (3) According to claims (1) and (2), the removal method is characterized in that a reinforcing bar cage for reinforcing the consolidation material constituting the anchoring length portion is arranged on the proximal end side of the bearing pressure member for anchoring. Anchor method.