JP6960771B2 - Construction method of cast-in-place concrete pile - Google Patents

Description

The present invention relates to a method of constructing a cast-in-place concrete pile.

Conventionally, in concrete placing when constructing cast-in-place concrete piles, a fragile layer called slime is formed on the upper part of the concrete, so a small amount (about 800 mm) of concrete is launched higher than the planned pile concrete top. There is. In this way, the surplus concrete provided on the upper part of the concrete is generally scraped off after root cutting, but the noise, vibration, and dust generated at that time may cause environmental problems in the neighborhood.

Therefore, in order to deal with these problems, for example, a method of sucking up excess concrete by vacuum before hardening of concrete, a method of setting concrete crushing material on pile reinforcing bars and removing the excess concrete crushed after root cutting, etc. It has been used in the past.

On the other hand, in relation to such a pile head processing method for cast-in-place concrete piles, for example, the techniques described in Patent Documents 1 and 2 are known. In Patent Document 1, after concrete is placed near the top of the planned pile, slime and the like on the concrete are removed, and then the final concrete is placed above the top of the planned pile, and the surplus thereof is obtained. The part is sucked and removed by a vacuum hose. Patent Document 2 inserts an injection pipe into the surplus portion of the pile head before hardening the concrete, injects air from the injection pipe to reduce the strength of the concrete, and then scrapes the surplus portion. ..

Japanese Unexamined Patent Publication No. 2004-263559 Japanese Unexamined Patent Publication No. 2001-288743

However, the above-mentioned conventional vacuum suction method may hinder efficient construction when the fluidity of concrete is low or when the pile reinforcing bars are an obstacle. Further, even with the method of setting the above-mentioned crushing material, there is a problem that the crushing material cannot be crushed as planned and the chipping work may have to be carried out in the end, resulting in low reliability.

Therefore, there has been a demand for a construction method having excellent workability, which can easily remove the surplus portion without crushing the concrete.

The present invention has been made in view of the above, and an object of the present invention is to provide a method for constructing a cast-in-place concrete pile in which a surplus portion can be easily removed without performing a crushing operation.

In order to solve the above-mentioned problems and achieve the object, the method of constructing a cast-in-place concrete pile according to the present invention is a method of constructing a cast-in-place concrete pile, and the pile head and the surplus portion above it. At the planned installation location, a step of placing a super-delayed concrete made by mixing a super-delaying agent into concrete to construct a pile head and a surplus part made of super-delayed concrete, and a step of super-delayed concrete in the surplus part. Before the start of hardening, the step of removing the super-delayed concrete in the surplus part, and after removing the super-delayed concrete in the surplus part, and before the start of hardening of the super-delayed concrete in the pile head, the pile head and the upper part of the pile It is characterized by including a step of inserting a connecting member for connecting the structure to be installed in the pile head into the ultra-delayed concrete of the pile head.

Further, another method of constructing a cast-in-place concrete pile according to the present invention is characterized in that at least one of a pile head reinforcing bar, a column main bar, and a column steel frame is inserted as a connecting member in the above-described invention.

Further, in another method of constructing a cast-in-place concrete pile according to the present invention, in the above-mentioned invention, the pile head and the structure installed on the upper part of the pile are semi-rigidly joined or pin-joined via a connecting member. It is characterized by that.

According to the method for constructing cast-in-place concrete piles according to the present invention, it is a method for constructing cast-in-place concrete piles, in which a super-delaying agent is mixed in concrete at the pile head and the planned installation location of the surplus portion above the pile head. The step of placing the super-delayed concrete to build the pile head and the surplus part made of the super-delayed concrete, and the super-delayed concrete of the surplus part before the start of hardening of the super-delayed concrete of the surplus part. For connecting the pile head and the structure installed on the top of the pile after removing the super-delayed concrete in the surplus part and before the start of hardening of the super-delayed concrete in the pile head. Since the connecting member is provided with a step of inserting the connecting member into the ultra-delayed concrete of the pile head, it is easy to remove the surplus portion and the concrete crushing work is eliminated, so that the workability is improved.

Further, according to another method of constructing a cast-in-place concrete pile according to the present invention, at least one of a pile head reinforcing bar, a column main bar, and a column steel frame is inserted as a connecting member, so that the pile head is inserted through such a connecting member. It has the effect of being able to connect and the structure above the pile.

Further, according to another method of constructing a cast-in-place concrete pile according to the present invention, the pile head and the structure installed on the upper part of the pile are semi-rigidly joined or pin-joined via a connecting member. It has the effect that it can be applied to piles constructed by the rigid joint construction method and the pin joint construction method.

FIG. 1 is a schematic procedure diagram (first half) showing an embodiment of a cast-in-place concrete pile construction method according to the present invention. FIG. 2 is a schematic procedure diagram (second half) showing an embodiment of a cast-in-place concrete pile construction method according to the present invention.

The method of constructing a cast-in-place concrete pile according to the present invention is a construction rationalization method utilizing the fact that the setting start time of concrete can be adjusted by adopting an ultra-delaying agent. By adopting super-delayed concrete mixed with a super-delaying agent as the concrete forming the top of the pile and combining this with the vacuum method that has been widely used in the past, it is possible to eliminate the chipping work of pile head concrete.

Hereinafter, embodiments of the method for constructing cast-in-place concrete piles according to the present invention will be described in detail with reference to the drawings. The present invention is not limited to this embodiment.

As shown in FIG. 1 (1), in the embodiment of the present invention, first, a cylindrical casing tube 10 is press-fitted into the ground G by using a press-fitting device (not shown) arranged on the ground GL (step S1). ). Subsequently, while protecting the hole wall 12 with the casing tube 10, excavation in the casing tube 10 and discharge of earth and sand are performed using a grab bucket or the like (step S2). In this way, the pile hole 14 is constructed. If the layer above the support layer of the pile from the ground near the ground surface is soft ground, a steel pipe is inserted up to the vicinity of the support layer to construct a pile hole.

Next, as shown in FIG. 1 (2), the reinforcing bar cage 16 is built in the pile hole 14 (step S3). The reinforcing bar cage 16 is built so that the upper end fits in the top end surface TL of the pile head 18 to be installed. Subsequently, the super-delayed concrete 22 in which the super-delaying agent is mixed in advance with the concrete is placed in the pile head 18 and the surplus portion 20 above the pile head 18 (step S4). In this way, the pile head 18 and the surplus portion 20 made of the ultra-delayed concrete 22 are constructed.

Next, as shown in FIG. 1 (3), before the start of hardening (condensation) of the super-delayed concrete 22 of the surplus portion 20, the super-delayed concrete 22 of the surplus portion 20 is sucked by a vacuum hose or the like (not shown). , Remove from the pile hole 14 (step S5).

Next, for example, as shown in FIG. 2 (1), before the start of hardening of the ultra-delayed concrete 22 of the pile head 18, the pile head 18 and the structure 24 such as a foundation installed on the upper part of the pile 100 are connected. The lower portion of the connecting member 26 (pile head reinforcing bar 26A) for connecting is inserted into the ultra-delayed concrete 22 of the pile head 18 (step S6).

Subsequently, before the ultra-delayed concrete 22 hardens, the casing tube 10 (not shown) is pulled out, and concrete is poured onto the pile head 18 up to the ground surface GL. By doing so, the cast-in-place concrete pile 100 can be constructed.

The connecting member 26 to be inserted in step S6 is not limited to the pile head reinforcing bar 26A as shown in FIG. 2 (1), but is not limited to the pile head reinforcing bar 26A as shown in FIG. It can be selected according to the situation. For example, as the connecting member 26, the column main bar 26B may be inserted as shown in FIG. 2 (2), or the column steel frame 26C may be inserted as shown in (3).

Since the connecting member 26 is inserted after the super-delayed concrete of the surplus portion 20 is sucked and removed, no concrete adheres. For this reason, it is possible to eliminate the work such as cleaning of the pile head fixing reinforcing bar, which has been conventionally performed. However, it is desirable to cure the connecting member 26 with respect to the backfill soil.

According to the construction method of the present embodiment, after placing the super-delayed concrete 22 as the concrete of the pile head 18 and the surplus portion 20, the surplus portion 20 is removed up to the top end surface TL of the pile head 18. After that, since the connecting member 26 (pile head reinforcing bar 26A, column main reinforcing bar 26B, column steel frame 26C) is built, the surplus portion 18 can be easily removed and the concrete crushing work is eliminated, so that the workability is improved. In particular, since super-delayed concrete obtained by mixing a super-delaying agent with concrete is used and the super-delayed concrete is absorbed before the start of hardening, a well-known vacuum method can be effectively applied.

Further, also by the construction method of the present embodiment, it is possible to obtain a pile having the same structural performance as the pile constructed by the above-mentioned conventional method. Compared to the above-mentioned conventional method, this construction method costs more such as super-delaying agent mixed in concrete, but in the construction area where neighborhood measures are required, there is no need for the cost of scraping pile head concrete and noise countermeasures. Therefore, the total cost can be reduced. In addition, since the chipping work of the pile head concrete is eliminated, the construction period can be shortened as compared with the conventional method of performing the chipping work. Furthermore, since it does not generate noise, vibration, or dust associated with chipping work, it is an environmentally friendly construction method. In addition, work safety during construction can be improved as compared with the conventional method of performing chipping work. Further, since the connecting material with the foundation member such as the pile head reinforcing bar does not adhere to the surplus concrete or the like, the structural performance can be improved.

In the above embodiment, the case of rigid joining in which the pile head 18 and the structure 24 such as the foundation installed on the pile head 18 and the structure 24 such as the foundation installed on the pile head 18 are completely fixed via the connecting member 26 has been described as an example. Is not limited to this, and is also applicable to piles constructed by a semi-rigid joint construction method or a pin joint construction method in which the pile head 18 and the structure 24 above the pile head 18 are not completely fixed.

As described above, according to the method for constructing cast-in-place concrete piles according to the present invention, it is a method for constructing cast-in-place concrete piles, and concrete is placed at the pile head and the planned installation location of the surplus portion above the pile head. Before the step of placing the super-delayed concrete mixed with the super-delaying agent to construct the pile head and the surplus part made of the super-delayed concrete, and the start of hardening of the super-delayed concrete in the surplus part, the surplus A structure to be installed on the pile head and the top of the pile after the step of removing the super-delayed concrete in the ridge and before the start of hardening of the super-delay concrete in the pile head after removing the super-delay concrete in the surplus. Since the step of inserting the connecting member for connecting with and into the ultra-delayed concrete of the pile head is provided, the surplus portion can be easily removed and the concrete crushing work is eliminated, so that the workability is improved.

Further, according to another method of constructing a cast-in-place concrete pile according to the present invention, at least one of a pile head reinforcing bar, a column main bar, and a column steel frame is inserted as a connecting member, so that the pile head is inserted through such a connecting member. Can be connected to the structure above the pile.

Further, according to another method of constructing a cast-in-place concrete pile according to the present invention, the pile head and the structure installed on the upper part of the pile are semi-rigidly joined or pin-joined via a connecting member. It can also be applied to piles constructed by the rigid joint construction method and the pin joint construction method.

As described above, the method for constructing a cast-in-place concrete pile according to the present invention is useful for treating the surplus of the pile head of the cast-in-place concrete pile, and in particular, the surplus portion without crushing the concrete. Suitable for removing.

10 Casing tube 12 Hole wall 13 Pile hole 16 Reinforcing bar cage 18 Pile head 20 Overlay part 22 Super delay concrete 24 Structure 26 Connecting member 26A Pile head reinforcing bar (connecting member)
26B Column main bar (connecting member)
26C column steel frame (connecting member)
100 cast-in-place concrete pile G ground GL ground TL top surface

Claims (2)

It is a method of constructing cast-in-place concrete piles.
A super-delayed concrete made by mixing a super-delaying agent with concrete is placed at the planned installation location of the pile head and the surplus part above it to construct the pile head and the surplus part made of super-delayed concrete. Steps and
Before the start of hardening of the super-delayed concrete in the surplus part, the step of removing the super-delayed concrete in the surplus part and
After removing the super-delayed concrete in the surplus part, before the start of hardening of the super-delayed concrete in the pile head, the pile head is used as a connecting member for connecting the pile head and the structure installed on the upper part of the pile. A method for constructing cast-in-place concrete piles, which comprises a step of inserting at least one lower portion of a reinforcing bar, a pillar main bar, and a pillar steel frame into ultra-delayed concrete of a pile head. The method for constructing a cast-in-place concrete pile according to claim 1, wherein the pile head and the structure installed on the upper part of the pile are semi-rigidly joined or pin-joined via a connecting member.

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