JPS6254931B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to cast-in-place reinforced concrete piles and methods of construction thereof.

Conventionally, cast-in-place reinforced concrete piles are generally constructed by placing cage-shaped reinforcing bars in a pile hole that is excavated at a predetermined location, and gradually pushing up concrete from the bottom of the pile hole using a tremie tube.
0.5 to 1 m), unsuitable concrete containing impurities such as drilling debris (slime) and fine bentonite particles and having a strength below a predetermined level is concentrated.

Therefore, the upper end of the pile is formed as an extra layer approximately 0.5 to 1 m higher than the specified pile cap surface,
After hardening, use a jackhammer to remove the concrete from this extra heap.
Pile cap treatment involves destroying and removing piles using concrete breakers, etc., but this process requires a lot of time and effort, resulting in decreased work efficiency, soaring costs, and noise and vibration pollution caused by the destruction work. There were many drawbacks such as the occurrence of various occupational diseases.

In addition, it is disclosed in Japanese Utility Model Application Publication No. 57-119838 that a steel cylindrical body is fitted to the pile head so that the pile head can resist horizontal bending and deformation, especially during earthquakes. However, as mentioned above, the steel cylindrical body only resists bending and deformation in the horizontal direction, but does not bear the vertical force, and the vertical force is borne exclusively by the concrete inside the steel cylindrical body. . Therefore, even in this case, if the impurity-containing concrete remains inside the steel cylinder, the desired pile cap strength cannot be obtained.

The present invention was proposed with the aim of eliminating such drawbacks.

That is, the cast-in-place reinforced concrete pile of the present invention has a pile head made of reinforced precast concrete, a cylinder mounted on cage-shaped reinforcing bars, and impurities washed up in the upper half of the cylinder. It is formed by mixed upper layer concrete and normal concrete poured into the lower half of the cylinder, and the outside diameter of the cylinder is the same as the outside diameter of the pile trunk, and the cylinder is mounted on the pile trunk. are doing.

As a result, vertical force is applied to the cylindrical body, and predetermined pile performance can be obtained even if the impurity-containing upper layer concrete is left as part of the pile head without being removed.

In addition, the method for constructing cast-in-place concrete piles of the present invention includes placing a cylindrical body made of reinforcing precast concrete on the cage-shaped reinforcing bars and having a guide surface inclined inwardly and upwardly on the lower part of the cylindrical body. The vertical reinforcing bars are installed on top of each other by binding and connecting them, and the cage-shaped reinforcing bars are installed in a pile hole with the same inner diameter as the outer diameter of the tubular body, and the pile cap surface is to obtain the upper end of the tubular body. concrete in the pile holes to form a pile trunk with the same outer diameter as the cylinder, and an upper layer of concrete mixed with impurities is placed in the upper half of the cylinder. In addition, normal concrete is pumped up until the lower half of the cylinder is filled, thereby constructing the desired pile.

In the following, regarding the illustrated embodiment, first a cast-in-place reinforced concrete pile A will be explained, and then a method for constructing the same will be explained.

The cast-in-place reinforced concrete pile A of the present invention is constructed in a pile hole 1 excavated at a predetermined location as shown in FIG. It is formed by twisting.

The cylindrical body 2 has a cylindrical shape made of precast concrete and has a cage-shaped reinforcing bar 5 in which a plurality of vertical bars 3 arranged in a circular shape are connected by a ring-shaped horizontal bar 4, and a guide slanted diagonally upward on the inside is provided in the lower part. A surface 6 is formed, and each vertical strip 3 projects vertically by a required length from the upper and lower end surfaces.

The cylindrical body 2 is placed on the cage-shaped reinforcing bars 8 buried in the concrete 7 cast in the pile hole 1.
By connecting the lower protruding portion 3a of the vertical reinforcement 3 to the horizontal reinforcement 9b and the horizontal reinforcement 9b in an overlapping joint, it is installed on board, and approximately the lower half is filled with normal concrete 7, and the concrete The upper half of the cylinder 2 is filled with an unsuitable upper layer concrete 7' having a strength below a predetermined level and containing impurities such as drilling residue (slime) and fine particles of bentonite. As is clear from Fig. 1, the outer diameter of the pile trunk and the outer diameter of the cylinder 2 are the same, and therefore,
The cylinder body 2 is mounted on the pile trunk.

In this cast-in-place reinforced concrete pile A, the vertical force applied to the pile head is borne by the cylindrical body 2, so that even if the upper layer concrete 7' of the concrete 7 is accommodated, there is no problem in the required performance of the pile.
The upper protruding portion 3b of the vertical bar 3 of the cylinder body 2 is used for connection to an upper structure (not shown).

Next, the construction method of the present invention for constructing the cast-in-place reinforced concrete pile A will be explained.

The upper side of the vertical bar 9a and the horizontal bar 9b of the cage reinforcing bar 8
Next, the lower protruding portions 3a of the longitudinal reinforcements 3 of the cylinder 2 are tied together and connected to the lap joint, thereby mounting the cylinder 2 on the cage reinforcing bars 8. The cage-shaped reinforcing bar 8 is placed in a pile hole 1 that has been excavated with the same inner diameter as the outer diameter of the cylinder 2 so that the upper end of the cylinder 2 corresponds to a predetermined pile cap surface to be obtained.

After that, a tremie tube (not shown) is inserted to the bottom of the pile hole 1, concrete 7 is poured out, and the tip of the tremie tube is gradually poured while keeping it buried in the concrete that has already been poured. As a result, a pile trunk with the same outer diameter as the cylinder 2 is formed, and the normal concrete 7 fills approximately the lower half from the bottom end of the cylinder 2, and an unsuitable upper layer concrete 7 containing impurities is formed. ′ fills the upper half of the cylinder 2.

In this case, the upper concrete layer 7' is easily guided inside the cylinder 2 by the guide surface 6 and rises. This upper layer concrete 7' remains contained within the cylinder 2.

As is clear from the above description, the cast-in-place reinforced concrete pile of the present invention has a pile head that is
Made of reinforced precast concrete,
It is formed by a cylindrical body installed on top of cage-shaped reinforcing bars, and an upper layer of impurity-containing concrete and normal concrete thrown up on the upper and lower half of the cylindrical body, and the outer diameter of the cylindrical body and the pile trunk are the same. , the cylindrical body rests on the pile trunk, and the vertical reinforcement of the cylindrical body and the vertical reinforcement of the cage reinforcing bar for the pile are bound and connected. Therefore, the vertical force applied to the pile head is borne by the cylindrical body, and the pile head as a whole can maintain a predetermined strength and performance without the need for conventional pile head treatments that are associated with various disadvantages.

In addition, the method for constructing cast-in-place reinforced concrete piles of the present invention includes installing a cylindrical body made of reinforced precast concrete on a cage-shaped reinforcing bar for the pile by binding and connecting the longitudinal bars of both, and Type reinforcing bars are placed in pile holes with the same inner diameter as the outside diameter of the cylinder, and concrete is poured into the pile holes to form a pile trunk with the same outside diameter as the outside diameter of the cylinder, and concrete is mixed with impurities. By pouring the upper layer of concrete to the upper half of the cylinder and the normal concrete to the point where the lower half of the cylinder is filled, the cylinder can be transformed into a pile trunk without performing conventional pile cap treatment. It is possible to accurately and easily construct a desired cast-in-place reinforced concrete pile that matches a predetermined pile cap height while being mounted on a vehicle. The cylindrical body has a guide surface on its lower part that is inclined inwardly and upwardly, so that
During concrete pouring, unsuitable upper layer concrete mixed with impurities and normal concrete are smoothly thrown into the cylinder without getting stuck in the lower part of the cylinder, and become integral.

[Brief explanation of the drawing]

Figure 1 is a longitudinal cross-sectional view of the main part of an example of a cast-in-place reinforced concrete pile of the present invention, and Figure 2 shows a cylinder made of reinforced precast concrete mounted on the upper side of the cage-shaped reinforcement for the pile. It is a partially cutaway perspective view. 2... Cylindrical body made of precast concrete with reinforcing bars, 3... Vertical bars, 4... Horizontal bars, 8... Cage type reinforcing bars, 7'... Upper layer concrete mixed with impurities, 7...
...Normal concrete.

Claims (1)

[Scope of Claims] 1. A cast-in-place reinforced concrete pile in which the bearing head is reinforced with a cylindrical body, wherein the cylindrical body is made of precast concrete with vertical and horizontal reinforcements, the vertical reinforcements protrude vertically, and By connecting the lower protruding part to at least the vertical reinforcement of the cage reinforcing bar through a lap joint, it is installed on top of the cage reinforcing bar, and the upper layer of concrete mixed with impurities is placed in the upper half of the cylinder. The lower half is filled with normal concrete, the outside diameter of the pile trunk formed by the normal concrete is the same as the outside diameter of the cylinder, and the cylinder also rests on the pile trunk. Cast-in-place reinforced concrete piles. 2. In the construction method of cast-in-place reinforced concrete piles, in which concrete is poured into a pile hole in which a cage-shaped reinforcing bar has been installed and a cylindrical body for reinforcing the pile head is attached, the method includes vertical and horizontal reinforcement, with the vertical reinforcement protruding vertically, and installing a precast concrete cylinder having a guide surface inclined inwardly and upwardly on the lower part on top of the cage-shaped reinforcing bars by binding and connecting at least the vertical bars of both; Place the cage-shaped reinforcing bars in a pile hole with the same inner diameter as the outer diameter of the cylinder.
The process of erecting the upper end of the cylindrical body to match the pile cap surface, and filling the pile hole with concrete to form a pile trunk with the same outer diameter as the cylindrical body, and removing impurities. A method for constructing a cast-in-place concrete pile, characterized in that the mixed upper layer concrete fills the upper half of the cylindrical body and the normal concrete fills the lower half of the cylindrical body.