JP2021143547A - Pile head treatment method - Google Patents

Abstract

To provide a pile head treatment method for dismantling an extra-banking concrete of an on-site construction pile, which does not require the work of scraping the side surface of the on-site construction pile and prevents the generation of noise and vibration.SOLUTION: In a pile head treatment method, a refrigeration pipe 13 embedded in concrete in advance is frozen and expanded to generate a crack, and an extra banking concrete part 12 of an on-site construction pile 11 is removed using the cracked part as a boundary. The refrigeration pipe is fixed to a pile bar 14 or a fixing hoop 15 of the on-site construction pile via a fixing reinforcing bar 16, and raises a refrigerant pipe 17 for injecting low temperature liquefied gas into the refrigeration pipe above the extra banking concrete part.SELECTED DRAWING: Figure 1

Description

The present invention relates to a pile head treatment method for dismantling a surplus concrete portion of a pile created on site.

Conventionally, as this type of pile head treatment method, the invention of the pile head treatment method and the frost weathering pipe disclosed in Japanese Patent No. 6475553 is known.

In this pile head treatment method, as shown in FIGS. 11A, 11B, and 11C, cracks are generated in the expansive crushing material 3 in which the surplus concrete portion 2 of the on-site pile 1 is buried in the concrete. The expansion crushing material 3 is a freezing pipe (freezing crushing pipe) 4 in which water is previously sealed and a cooling portion is included, which is a construction method in which the cracked portion is removed at the boundary to perform pile head treatment. This is a method of burying the freezing pipe 4 in concrete and then injecting liquid nitrogen into a cooling unit to freeze water to freeze and expand the freezing pipe 4 to generate cracks (see Patent Document 1).

According to the pile head treatment method having such a configuration, not only the pile head treatment can be performed with low noise and low vibration, but also cracks are easily generated and the dismantling workability of the surplus concrete is improved.

Japanese Patent No. 6475553

(B) In this conventional pile head treatment method, prior to injecting liquid nitrogen into the cooling portion of the refrigerating pipe 4, it is necessary to scrape the side surface of the on-site pile 1 in order to find the injection port of the cooling portion. As a result, there is a problem that noise and vibration are generated.

In addition to that, (b) Conventionally, the pile main bar 5 is covered with a curing material made of foamed polyethylene as an edge cutting material with the surplus concrete portion 2, but as a result, plastic waste is attached to the surplus concrete waste. Will be mixed in, and there is a problem in treating industrial waste.

(C) Conventionally, the refrigerating pipe 4 is attached and fixed substantially horizontally at the position of the planned line where cracks are to be generated at the number line or the like via the reinforcing support reinforcing bar 6 with respect to the pile main reinforcing bar 5. In this case, there is a problem that the refrigerating pipe 4 may be left in the pile body 1a after the surplus concrete portion 2 is pulled out.

(D) Conventionally, as shown in FIGS. 11A and 11B, a plurality of, for example, 6 refrigerating pipes 4 are attached and fixed, but in this case, the on-site construction pile 1 has a small diameter of about 1200φ or less. In the case of piles, there is a problem that the presence of a plurality of refrigerating pipes 4 makes it difficult for the tremie pipe for placing concrete to pass through the space 8, and as a result, it is difficult to place concrete.

(E) Conventionally, there is a type in which the on-site construction pile 1 is a cast-in-place steel pipe concrete pile and the main bar does not extend to the pile head. In this case, there is a problem that the freezing pipe 4 cannot be attached to the pile main bar 5 of the reinforcing bar cage 7.

Therefore, in the pile head treatment method in the conventional example, (a) the work of scraping the side surface of the on-site pile 1 in order to find the injection port of the cooling part of the freezing pipe 4 is eliminated to prevent the generation of noise and vibration. In particular, it has an essential solution.
Furthermore, it is possible to prevent the situation where plastic dust is mixed into the (b) surplus concrete waste, and to eliminate the situation where the refrigerating pipe 4 is left in the pile body 1a after the (ha) surplus concrete portion 2 is pulled out. , (Ni) Even if the on-site construction pile 1 is a small-diameter pile, concrete can be placed smoothly. However, there is a problem that must be solved by attaching and fixing the refrigerating pipe 4.

The gist of the present invention for solving the above-mentioned problems of the conventional example is that the surplus concrete portion of the on-site construction pile is frozen and expanded by freezing and expanding a refrigerating pipe embedded in the concrete in advance to generate cracks, and the cracked portion is defined as a boundary. The refrigerating pipe is fixed to the pile main bar or the fixing hoop of the on-site construction pile via the fixing reinforcing bar, and the low-temperature liquefied gas is injected into the refrigerating pipe. A refrigerant pipe for this purpose is set up above the surplus concrete portion.

Further, in the freezing pipe, one end of the fixing reinforcing bar is fixed to the pile main bar or the fixing hoop of the surplus concrete portion;
In the case of a small-diameter pile having a diameter of 1200 mm or less, one of the refrigerating pipes is fixed to the pile main bar or the fixing hoop via the fixing reinforcing bar.
Is included.

The gist of the present invention for solving the above-mentioned problems of the conventional example is that the surplus concrete portion of the on-site pile is frozen and expanded by freezing and expanding a refrigerating pipe embedded in the concrete in advance to generate cracks, and the cracked portion is defined as a boundary. The refrigerating pipe is fixed to the pile main bar or the fixing hoop of the on-site construction pile via a fixing reinforcing bar, and the pile main bar is attached to the surplus concrete. A sheath is attached as an edge cutting material with the part.

The gist of the present invention for solving the above-mentioned problems of the conventional example is that the surplus concrete portion of the on-site pile is frozen and expanded by freezing and expanding a refrigerating pipe embedded in the concrete in advance to generate cracks, and the cracked portion is defined as a boundary. The refrigerating pipe is installed at the installation position inside the on-site construction pile and outside the reinforcing bar cage composed of the pile main bar and the fixing hoop. ..

The gist of the present invention for solving the above-mentioned problems of the conventional example is that the surplus concrete portion of the steel pipe concrete pile is frozen and expanded by freezing and expanding a refrigerating pipe previously embedded in the concrete to generate cracks, and the cracked portion is defined as a boundary. The refrigerating pipe is a pile head treatment method for removing the pile head, in which a temporary reinforcing bar is fixed inside the steel pipe concrete pile and fixed to the temporary reinforcing bar via the fixing reinforcing bar. ..

According to the pile head treatment method according to claim 1 of the present invention, a refrigerant pipe for injecting liquid nitrogen (low temperature liquefied gas) into the refrigerating pipe is set up on the upper part of the surplus concrete portion, which is a conventional example. As described above, it is not necessary to perform the squeezing work to find the injection port of the cooling part of the refrigerating pipe, and as a result, the noise and vibration associated with the squeezing work are not generated. In addition, the liquid nitrogen injection work can be started promptly.
Further, since the liquid nitrogen stays in the freezing pipe for a long time, the freezing effect is maintained for a long time, and as a result, the amount of liquid nitrogen used is reduced by about 20%, which is an excellent effect.

In the freezing pipe, one end of the fixing reinforcing bar is fixed to the pile main bar of the surplus concrete part or the fixing hoop, so that after the surplus concrete part is pulled out, the freezing pipe is attached to the pile body as in the conventional example. It has an excellent effect that it is not left behind, and as a result, no extra work is required to scrape the freezing tube.

In the case of small-diameter piles with a diameter of approximately 1200 mm or less, one refrigerating pipe is fixed to the pile main bar or fixing hoop via fixing reinforcing bars, so that there is only one refrigerating pipe. The space becomes wider, and concrete can be placed in the space through a tremie pipe. In addition, it has an excellent effect that cracks due to freezing expansion of the freezing tube occur without any problem.

According to the pile head treatment method according to claim 4 of the present invention, the pile main bar is provided with a sheath as an edge cutting material with the excess concrete portion, so that plastic dust does not mix in the excess concrete waste.
Furthermore, the load applied to the lifting machine when the surplus concrete portion is pulled out is reduced.
Further, the curing material for the pile main bar may be not only a sheath but also a hard and thin material such as a paper void or a VP pipe. It has various excellent effects that it does not affect.

According to the pile head treatment method according to claim 6 of the present invention, the refrigerating pipe has a temporary reinforcing bar welded and fixed to the inside of the steel pipe concrete pile, and is fixed to the temporary reinforcing bar via a fixing reinforcing bar. As a result, even when the on-site construction pile is a cast-in-place steel pipe concrete pile and the main bar does not extend to the pile head, the refrigerating pipe can be attached and fixed to the temporary reinforcing bar, which is an excellent effect.

It is a top view of the pile made in the field in the pile head processing method which concerns on this invention. It is a side view of the pile made in the field in the pile head processing method which concerns on this invention. It is a figure which shows the relationship between the total pile diameter length and the number of nitrogen cylinders used. It is a figure of the pull-out load ratio of the surplus concrete part ÷ the surface area of the reinforcing bar. It is a figure which shows the relationship between the contact surface area of a pile main bar and the pull-out load ratio with the surplus concrete part for each work place, and for each type of edge cutting material. It is a top view of the small diameter pile in the pile head processing method which concerns on this invention. It is a side view of the small-diameter pile in the pile head processing method which concerns on this invention. It is a top view of the steel pipe concrete pile in the pile head processing method which concerns on this invention. It is a side view of the steel pipe concrete pile in the pile head processing method which concerns on this invention. It is a block diagram which shows the construction procedure of a pile head processing method. (A) It is a top view of the pile created in the field in the pile head processing method which concerns on a conventional example. (B) It is a side view of the pile made at the same site. (C) is a cross-sectional view taken along line XX in the side view.

Next, an embodiment of the present invention will be described with reference to the drawings. In the present invention, as shown in FIGS. 1 and 2, the surplus concrete portion 12 of the on-site pile 11 is freeze-expanded by freezing and expanding the freezing pipe 13 previously embedded in the concrete to generate cracks, and the cracked portion is formed. It is a pile head treatment method that removes at the boundary.
The refrigerating pipe 13 is mounted and fixed substantially horizontally at the position of the planned line where cracks are to be generated, and is fixed to the pile main bar 14 or the fixing hoop 15 of the site-developed pile 11 via the fixing reinforcing bar 16. do.
As shown in FIGS. 1 and 2, the freezing pipe 13 may be installed at the installation position 25 inside the on-site construction pile 11 and outside the reinforcing bar cage composed of the pile main bar 14 and the fixing hoop 15. ..

In the present invention, as shown in FIGS. 1 and 2, a refrigerant pipe 17 for injecting liquid nitrogen (low temperature liquefied gas) into the refrigerating pipe 13 is raised above the surplus concrete portion 12, and the refrigerant is used. The injection port 17a of the pipe 17 is located above the surplus concrete portion 12. Further, as shown in FIG. 2, the base portion 17b of the refrigerant pipe 17 is connected to the freezing pipe 13 so that the inside thereof can be filled with liquid nitrogen.

By raising the refrigerant pipe 17 above the surplus concrete portion 12 in this way, it is not necessary to perform the squeezing work for finding the injection port of the cooling portion of the freezing pipe as in the conventional example, and the squeezing work can be performed. No noise or vibration is generated. In addition, the liquid nitrogen injection work can be started promptly.

Further, since the liquid nitrogen stays in the freezing pipe 13 for a long time, the freezing effect is maintained for a long time, and as a result, the amount of liquid nitrogen used is reduced by about 20%.

FIG. 3 is a diagram showing the relationship between the total pile diameter length and the number of nitrogen cylinders used. The vertical axis shows the number of nitrogen cylinders used, and the horizontal axis shows the total pile diameter length (m). The ▲ mark in the figure is for the triangular arrangement, the ■ mark is for the parallel arrangement, and the ● mark is for the upper supply of the present invention, indicating that the number of nitrogen cylinders used is reduced by about 77%. ..

As shown in FIG. 2, a sheath 18 is attached to the pile main bar 14 as an edge cutting material with the surplus concrete portion 12. Specifically, a chipping cover (not shown) is attached around the pile main bar 14, a sheath 18 is attached on the cover, and the sheath 18 is attached to the upper and lower portions thereof by using a number wire or the like.
By attaching the sheath 18 around the pile main bar 14 in this way, plastic dust is not mixed into the surplus concrete glass after the surplus concrete portion 12 is pulled out. Further, the load applied to the lifting machine when the surplus concrete portion 12 is pulled out is reduced.
Further, the curing material for the pile main bar 14 may be not only a sheath but also a hard and thin material such as a paper void or a VP pipe. Does not affect.

FIG. 4 is a comparison graph of the pile head pull-out test results at the three work places of the work place A, the work place B, and the work place C. A VP pipe (PVC pipe) is used, the work place B uses a sheath and a chip cover, and the work place C uses a chip cover.
The vertical axis shows the pull-out load ratio of the surplus concrete part ÷ the surface area of the reinforcing bar, and the smaller the value on the vertical axis, the smaller the resistance required for pulling out. In addition, the ■ mark in the graph indicates the average value.

Figure 5 is a representation of the test results of FIG. 4 in a different graph, the ordinate indicates the pulling load ratio of excess weld concrete portions, the horizontal axis represents the rebar adhesion area (mm ² × 10 ⁶⁾ There is.
The smaller the value on the vertical axis of the graph, the smaller the resistance required for drawing. The solid line A is the case where the sheath of the work place B is used, and the solid line B is the case where the chipping cover of the south sand is used. It is shown that pulling out can be performed with less resistance when using a sheath.

As shown in FIGS. 1 and 2, one end portion 16a of the fixing reinforcing bar 16 connected to the freezing pipe 13 extends to the pile main reinforcing bar 14 or the fixing hoop 15 in the surplus concrete portion 12 and is fixed thereto. ..
The freezing pipe 13 has a length of about 500 to 1000 mm as an example, and fixing reinforcing bars 16 are connected to one end side and the other end side, respectively. The fixing reinforcing bar 16 stands up and has a bent portion 16b in the middle, and one end portion 16a is fixed to the pile main reinforcing bar 14 or the fixing hoop 15 of the surplus concrete portion 12.

By fixing the one end portion 16a of the fixing reinforcing bar 16 to the pile main bar 14 or the fixing hoop 15 in the surplus concrete portion 12 in this way, when the surplus concrete portion 12 is pulled out, the freezing pipe 13 Will be attached to the surplus concrete portion 12. That is, since the freezing pipe is not left on the pile body as in the conventional example, extra work such as scraping the freezing pipe does not occur.

As shown in FIGS. 6 and 7, in the case of a small-diameter pile having a diameter of 1200 mm or less, one refrigerating pipe 13 is connected to the pile main bar 14 or the fixing hoop 15 via the fixing reinforcing bar 16. And fix it.
In this case, since there is only one freezing pipe 13, the space 19 becomes wide, and concrete can be placed in the space 19 through a tremie pipe (not shown). Further, cracks due to freezing expansion of the freezing tube 13 occur without any problem.

As shown in FIGS. 8 and 9, in the present invention, the surplus concrete portion 12 of the steel pipe concrete pile 20 is frozen and expanded by freezing and expanding the refrigerating pipe 13 previously embedded in the concrete to generate cracks, and the cracked portion is formed. It is a pile head treatment method that removes at the boundary.
In the freezing pipe 13, the temporary reinforcing bar 21 is welded and fixed to the inside of the steel pipe concrete pile 20, and fixed to the temporary reinforcing bar 21 via the fixing reinforcing bar 16.

A part of the work procedure about the pile head treatment method of the steel pipe concrete pile 20 will be described. First, the temporary reinforcing bar 21 is welded and fixed to the inside of the steel pipe concrete pile 20, the sheath 22 is put on the temporary reinforcing bar 21, the fixing hoop 23 is attached, the refrigerating pipe 13 is attached, the fixing hoop 24 is attached, and the refrigerating pipe 13 is attached. A refrigerant pipe 17 for injecting liquid nitrogen into the concrete pipe 17 is set up.

By welding and fixing the temporary reinforcing bars 21 to the inside of the steel pipe concrete pile 20 in this way, the refrigerating pipe 13 is used even when the cast-in-place steel pipe concrete pile 20 does not extend the main reinforcing bar to the pile head. Can be attached and fixed to the temporary reinforcing bar 21.

Next, the construction procedure for the pile head treatment method will be described. First, as shown in the block diagram showing the construction procedure of the pile head treatment method of FIG. 10, liquid nitrogen is carried in. As for the construction contents, liquid nitrogen will be carried in when the pile head is exposed by the root cutting work.

Then, the injection port 17a of the refrigerant pipe 17 is confirmed. As for the construction contents, the injection port 17a of the refrigerant pipe 17 is confirmed, and if it is buried in the surplus concrete portion 12, it is scraped out.
It is preferable to insert a cutter at the pile head level in order to clean the line when the excess concrete portion 12 is removed.
In the case of pile head steel pipe winding, the work is not required at this stage because it is performed at the stage of forming and chipping.

Further, the surplus concrete portion 12 of the pile head is processed. As for the construction contents, the liquid nitrogen container and the refrigerating pipe are connected by pipes, liquid nitrogen is supplied after completion, and it is confirmed that horizontal cracks occur in the surplus concrete portion 12 of the pile head.

Then, the surplus concrete portion 12 is removed. As for the construction contents, the surplus concrete portion 12 is lifted and removed after the frozen pile head treatment is completed. Depending on the lifting plan, the surplus concrete portion 12 is divided before removal.

1 On-site construction pile 1a Pile body 2 Overlay concrete part 3 Expandable crushing material 4 Refrigeration pipe 5 Pile main reinforcement 6 Reinforcing support reinforcement 7 Reinforcing bar cage 8 Space 11 On-site construction pile 12 Overlay concrete part 13 Refrigeration pipe 14 Pile main reinforcement 15 For fixing Hoop 16 Reinforcing bar for fixing 16a One end 16b Bent part 17 Refrigerator pipe 17a Injection port 17b Base 18 Sheath (curing material: steel sheath, paper void, VP pipe, etc.)
19 Space 20 Steel pipe Concrete pile 21 Temporary reinforcing bar 22 Sheath (curing material: steel sheath, paper void, VP pipe, etc.)
23, 24 Hoop for fixing 25 Installation position

Claims (6)

This is a pile head treatment method in which the surplus concrete part of the on-site pile is frozen and expanded by freezing and expanding a refrigeration pipe buried in the concrete in advance to generate cracks, and the cracked part is removed as a boundary.
The freezing pipe is fixed to the pile main bar or the fixing hoop of the on-site construction pile via the fixing reinforcing bar.
A pile head treatment method characterized in that a refrigerant pipe for injecting a low-temperature liquefied gas into the freezing pipe is set up above the surplus concrete portion. The pile head treatment method according to claim 1, wherein the freezing pipe has one end of the fixing reinforcing bar fixed to the pile main bar of the surplus concrete portion or the fixing hoop. In the case of a small-diameter pile having a diameter of 1200 mm or less, one of the refrigerating pipes is fixed to the pile main bar or the fixing hoop via the fixing reinforcing bar. The pile head treatment method according to claim 1. This is a pile head treatment method in which the surplus concrete part of the on-site pile is frozen and expanded by freezing and expanding a refrigeration pipe buried in the concrete in advance to generate cracks, and the cracked part is removed as a boundary.
The freezing pipe is fixed to the pile main bar or the fixing hoop of the on-site construction pile via the fixing reinforcing bar.
A pile head treatment method characterized in that a sheath is attached to the pile main bar as an edge cutting material with the surplus concrete portion. This is a pile head treatment method in which the surplus concrete part of the on-site pile is frozen and expanded by freezing and expanding a refrigeration pipe buried in the concrete in advance to generate cracks, and the cracked part is removed as a boundary.
A pile head treatment method characterized in that the freezing pipe is installed at an installation position inside the on-site construction pile and outside a reinforcing bar cage composed of a pile main bar and a fixing hoop. This is a pile head treatment method in which the surplus concrete part of a steel pipe concrete pile is frozen and expanded by freezing and expanding a refrigerated pipe buried in the concrete in advance to generate cracks, and the cracked part is removed as a boundary.
The freezing pipe is a pile head treatment method characterized in that a temporary reinforcing bar is fixed inside the steel pipe concrete pile and fixed to the temporary reinforcing bar via the fixing reinforcing bar.

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