JPH0355314A - Removable anchoring work - Google Patents

Abstract

PURPOSE:To make the removal of anchor easier after used while securing the bearing force of anchor in use by a method in which reinforcing parts are attached at a fixed pitch to the peripheral side of a tensile steel in an anchor assembly consisting of the tensile steel of unbonded structure and a load part. CONSTITUTION:An anchor assembly 10 is made up of a tensile steel 20 of unbonded structure, a load part 30, and reinforcing parts 40 attached at a fixed pitch to the peripheral side of the steel 20. The load part 30 has a domed peripheral face which hooks the U-shaped folded portion of the steel 20 to resist tension force when in use. The reinforcing parts 40 serve to avoid concentration of tension force on the part 30 when introducing tensile force into the steel 20 and also to disperse it into the steel 20 in the fixed length range of the anchor assembly. The removal of anchor can thus be easily attained while increasing the bearing force of anchor, an the cracking of solidifying material can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a removal anchor construction method that provides a large anchor strength during use and allows the tensile steel of the anchor to be removed after use.

<Prior Art> Various anchor removal methods have been proposed in which the anchor is removed after use so that it does not become an underground obstruction.

Anchor removal methods are divided into two methods: one is to remove anchors mechanically, the other is to be removed mechanically.
It is broadly divided into methods that use chemical methods to remove it, but mechanical methods are often used because of its ease of removal.

In the mechanical removal method, tI for the anchor structure is preliminarily removed.
It is removable by using a tensile steel wire (PC steel wire) assembled with 4 wires and a specially coated drawing steel material, and when removing it, tensile force is introduced into the drawing steel material and pulled out one by one from the anchor. Anchor construction method and bondless anchor construction method belong to this category.

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

<B> In conventional removable anchors, anchor strength and removability are in a trade-off relationship, and it is technically difficult to satisfy both at the same time.

It is unavoidable that tensile steel material undergoes creep during use and the anchor strength decreases over time.

If the decline in the anchor strength is left unaddressed, there is a fatal problem in that the anchor function cannot be achieved.

<C> The introduced tensile force is locally concentrated at the bent part of the tensile steel material, and a force acts to split the consolidated material into wedge shapes.

In order for an anchor to exhibit sufficient strength, it is necessary for the anchorage ground to have a restraining force sufficient to prevent the hardwood from splitting.

If the anchoring ground is sand, gravel, or clay-based ground, the binding force will be small, allowing the consolidated material to split.

Therefore, the anchorage tends to be limited to solid ground, or the anchor tends to be long because it needs to be anchored deep underground, which is disadvantageous from an economical and construction standpoint.

In conventional removable anchors, anchor strength and removability are in a trade-off relationship, and it is difficult to satisfy both at the same time.

OBJECT OF THE INVENTION The present invention was developed to solve the above-mentioned problems, and its purpose is to ensure a large anchor strength during use without adversely affecting workability, and An object of the present invention is to provide a removal anchor construction method that allows subsequent removal to be carried out easily and economically.

<Means for Solving the Problems> The present invention involves inserting an anchor assembly assembled with an unbonded tensile steel material and a load-bearing member into an anchor hole, and then filling the anchor hole with a consolidating material. In the removal anchor construction method, which waits for the solidified material to harden and then settles under tension, reinforcing materials are integrally provided at regular intervals over the anchorage area of the tensile steel material, and an anchor assembly is used and introduced into the tensile steel material. The present invention relates to a removal anchor construction method, which is characterized in that tensile force is evenly transmitted to the entire consolidated material via a reinforcing material and fixed.

Furthermore, the present invention includes inserting an anchor assembly assembled with an unbonded tensile steel member and a load-bearing member into an anchor hole,
Next, the inside of the anchor hole l: In the removal anchor construction method, in which a consolidation material is filled and the anchor is fixed under tension after the consolidation material has hardened, the length of the anchor hole is 1.
Using an anchor assembly with reinforcing materials integrally provided at intervals of 0 to 2.0 times, the tensile force introduced into the tensile steel material is evenly transmitted to the entire consolidated material through the reinforcing materials and fixed. Regarding the featured removal anchor construction method.

<Description of the present invention> The present invention will be explained in detail below.

<A> Structure of anchor assembly The anchorage length of anchor assembly 10 is shown in FIG.

The anchor assembly 10 consists of a tensile steel member 20 of an unpond structure, a load-bearing body 30, and reinforcing members 40 attached to the circumferential surface of the tensile steel member 20 at a constant pitch.

In the figure, 50 is an anchor hole, and 60 is a consolidation material such as mortar.

<Exposure> Tensile steel The tensile steel 20 has an unpond structure in which grease is applied over the entire length of a PC steel wire and its peripheral surface is covered with a resin sheath.

<C> Load-bearing body The load-bearing body 30 is a member that has a dome-shaped peripheral surface, holds the bent part of the tensile steel material 20 folded back in a U-shape, and resists tension during use. You can use the structure of

<2> Reinforcement material The reinforcement material 40 is intended to increase the strength of the anchor without adversely affecting the removal of the anchor.

That is, the reinforcing member 40 is a reinforcing member that prevents the tension force from being concentrated on the load-bearing body 30 and disperses it to the tensile steel material 20 within the range of the anchor length when tension force is introduced into the tensile steel material 20. .

The reinforcing materials 40 are attached at a constant pitch over the range of the anchor length portion of the tensile steel material 20.

The reinforcing material 4o is made of a material having a larger deformation coefficient than the consolidation material 60, such as steel, glass fiber, carbon fiber, or resin.

<E> Installation pitch of reinforcing material A preferable installation pitch P of the reinforcing material 40 is approximately 1.0 to 2.0 times the diameter D of the anchor integrally (the diameter of the anchor hole 50).

The mounting pitch P of the reinforcing member 40 is set as described above for the following reasons.

When a tensile force is applied to the anchor, the bearing pressure portion becomes highly compressed, and subsequently a shear failure surface occurs in the anchor.

Although this varies depending on the size of the bearing pressure part, it has been observed through experiments that the anchor fixed part often occurs within a range of 45° to 60° from the bearing pressure part.

If the attachment pitch P of the reinforcing material 40 is larger than twice the diameter D of the anchor, the effect of preventing shear failure of the consolidation material 60 will be reduced.

Furthermore, if the bitch P is less than 1 times the diameter D of the anchor, the effect of preventing shear failure of the solidified material 60 does not change much, but it can be said to be wasteful when considering workability and economic efficiency. .

Therefore, in terms of the effect of preventing shear failure of the consolidation material 60, workability, and economic efficiency, the attachment pitch P of the reinforcing material 40 is preferably about 1 to 2 times the diameter D of the anchor.

<F> Construction method The construction method of the present invention can be basically constructed in almost the same steps as the conventional removal anchor construction method, except that the assembly structure of the anchor assembly 10 is different.

That is, the intermediate portion of the unbonded tensile steel material 20 is folded back into a U-shape along the curve of the load-bearing body 30.

A predetermined number of tensile steel members 20 are moored to the load-bearing body 30, and then tied together.

Next, reinforcing members 40 are attached to the outer periphery of each tensile steel member 20 at equal pitches, and the anchor assembly 10 is assembled.

Note that the reinforcing material 40 may be a simple binding means that is bound to the tensile steel material 20 using a binding wire.

After that, as in the conventional case, insert the anchor assembly 10 into the anchor hole 5.
0 and filled with a consolidating material 60, and after waiting for the consolidating material 60 to solidify, the tensile beam material 20 is tensioned and fixed.

Since the tensile steel material 20 has an unbonded structure, the introduced tension force is transmitted to the load-bearing body 30 in the same manner as before.

Without the reinforcing material 40, force would be locally concentrated at the bent portion of the tensile steel material 20, and force would act to split the consolidated material 60 into wedge shapes.

However, since the reinforcing material 40 structurally integrates both the tensile steel material 20 and the consolidation material 60, the introduced tension force is transmitted from the tensile steel material 20 through the reinforcement material 40 to the entire consolidation material 60. evenly transmitted.

When removing the anchors, a tensile force is applied to one of the tensile steel members 20 of each set and the anchors are pulled out one by one.

Since the resin sheath is interposed between the PCJll wire and the consolidation material 60, the force required to extract each set of tensile steel material 20 is small.

<G> Consideration of Anchor Resistance Figure 2 shows a diagram of the relationship between the tensile load and the amount of deformation of the existing anchor and the anchor of the present invention.

Existing anchors are of the friction type, which uses the circumferential friction force by attaching the entire length of the anchor to the solidified material, and the bearing pressure type, which uses the interlocking effect by pressing the bent part of the anchor against the solidified material. In the figure, A indicates the friction type, B indicates the bearing type, and C indicates the anchor of the present invention.

According to the figure, it can be seen that the anchor C of the present invention has a load-bearing characteristic close to that of the friction type A anchor.

Therefore, the anchor C of the present invention can be applied to soils with weak binding force, such as sand, gravel, and solidified cohesive soil, which have hitherto had many problems, and can ensure sufficient strength.

Further, FIGS. 3 to 5 show the distribution of surface resistance in the anchoring parts of the conventional anchor and the anchor of the present invention.

FIG. 3 shows a conventional friction type, FIG. 4 shows a conventional bearing pressure type, and FIG. 5 shows an anchor according to the present invention.

For the bearing type anchor shown in Figure 4, if sufficient restraining force cannot be expected in the ground, bond failure will progress sequentially starting from the tip of the anchor at the bottom of the drawing, and the yield strength will increase in proportion to the length of the anchorage. I understand that you can't expect anything.

On the other hand, it can be seen that in the anchor of the present invention shown in FIG. 5, even if the tension is increased, this stress does not act locally and is evenly distributed throughout.

Further, in the anchor of the present invention, it can be expected that the yield strength increases in proportion to the length of the anchoring portion.

Therefore, the anchor of the present invention exhibits a circumferential surface resistance equivalent to that of the friction type anchor shown in FIG. 3, and is therefore superior in terms of strength and reliability with respect to strength is improved.

Furthermore, depending on the design of the reinforcing material 40, the ACAN of the present invention can provide a peripheral surface resistance greater than that of conventional friction types.

<Example 1> Examples of the present invention will be described below.

The embodiment shown in FIG.
0 is used to assemble the anchor assembly 10.

The intersections of each reinforcing material 40 and the tensile steel material 20 are bound using a binding wire or the like.

<Example 2> FIG. 6 shows another embodiment.

This embodiment has a structure in which a long reinforcing material 41 is spirally wound around the tensile steel material 20.

The spiral pitch P of the reinforcing member 41 needs to be set to approximately 1.0 to 2.0 times the diameter D of the integral anchor (the diameter of the anchor hole 50).

By spirally winding the reinforcing material 41 as in this embodiment, the number of fixing locations for fixing the reinforcing material 41 to the tensile steel material 20 can be reduced.

In other words, in order to attach the reinforcing material 41, 1 pitch Pm
There is no need to fix the reinforcing material 41 to the tensile steel material 20 at two locations, the starting end and the ending end, or several locations along the way.
Just fix it to 0.

<Example 3> The above example describes the case where the tensile steel material 20 folded back by the load-bearing body 30 is stretched linearly and used.

In this embodiment, as shown in FIG.
A ring-shaped reinforcing member 40 may be integrally attached to 1.

In this embodiment, the shape of the tensile steel material 20 changes into uneven shapes like a number of gourds connected together, and moreover, the tensile steel material 20 wraps around the consolidated material 60 between the reduced diameter portions 21.

Therefore, there is an advantage that the engagement between the consolidation material 60 and the tensile steel material 20 is improved, and the efficiency of distributing the load applied to the load-bearing body 30 is improved.

Note that the mounting pitch of the reinforcing members 40 is the same as in the previously described embodiments.

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

<B> Sufficient anchor strength can be obtained without impairing the removability of the removal anchor.

<Open> The tensile force introduced into the tensile steel material can be evenly distributed throughout the anchoring part to prevent splitting of the consolidated material.

Therefore, high yield strength can be ensured even on ground with weak binding force, and it becomes possible to apply it to ground such as sand and sand, which has been difficult to adopt in the past.

<C> In the present invention, the yield strength of the anchor increases in proportion to the length of the anchoring portion.

Therefore, it is advantageous in terms of design since it is possible to avoid increasing the length of the anchor.

(2) It can also be applied to semi-permanently fixed anchor construction methods that are not intended to be removed.

When applied to general anchor construction methods, the strength of the anchor will be further enhanced.

[Brief explanation of drawings]

Figure 2: A sectional view of the anchoring part of the removable anchor construction method according to the present invention. Figure 2: A diagram showing the relationship between tensile weight loss and deformation in the conventional anchor and the anchor of the present invention. Figure 3: Distribution diagram of surface resistance at the anchorage part of a conventional friction type anchor Figure 4: Distribution diagram of circumferential resistance at the anchorage area of a conventional bearing type anchor Figure 5 Figure 6: Explanatory diagram of another embodiment in which reinforcing material is attached in a spiral shape Figure 7: Explanatory diagram of another embodiment in which a reduced diameter portion is formed in the tensile steel material 1st Figure To-o-11 Porridge 3 Figure 4

Claims (2)

[Claims] (1) Insert the anchor assembly assembled with the unbonded tensile steel material and the load-bearing body into the anchor hole, then fill the anchor hole with a consolidation material, wait for the consolidation material to harden, and then tighten and fix it. In the removal anchor method, an anchor assembly is used in which reinforcing members are integrally installed at regular intervals over the anchorage area of the tensile steel, and the tensile force introduced into the tensile steel is transferred to the consolidated material through the reinforcing material. A removal anchor construction method that is characterized by spreading and fixing evenly throughout the entire area. (2) Insert the anchor assembly assembled with the unbonded tensile steel material and the load-bearing body into the anchor hole, then fill the anchor hole with a consolidation material, wait for the consolidation material to harden, and then tighten and fix it. In the removal anchor method, an anchor assembly is used in which reinforcing materials are integrally provided at intervals of 1.0 to 2.0 times the diameter of the anchor body over the range of the anchorage part of the tensile steel material, and the reinforcing material is installed in the tensile steel material. The removal anchor method is characterized by transmitting the tensile force evenly throughout the consolidated material through the reinforcing material and fixing it.