JPH0718155B2 - Method for constructing cast-in-place concrete reinforced concrete pile and reinforced basket used for this method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for constructing cast-in-place concrete reinforced concrete bottom piles by an earth drill method, a reverse method, a benot method, etc., and a reinforced cage used for the method.

[0002]

2. Description of the Related Art Conventionally, cast-in-place concrete reinforced concrete bottom piles, as shown in FIGS. 8 and 9, do not have reinforcing bars in the widened portion of the pile, so that the shearing force generated by the ground reaction force applied to the widened portion of the pile is Since it will be supported by the concrete of the pile widening part, the inclination angle θ of the pile bottom part
Must be designed to be 12 degrees or less, and if the soil bearing capacity of the pile is to be increased, that is, if the bottom area of the pile widened portion is to be increased, the height h of the pile widened portion must be increased. The cost has risen due to the increase in In addition, the cast-in-place concrete reinforced concrete bottom pile is constructed by suspending the rebar cage B formed by connecting the required number of main reinforcements 1 by the hoop reinforcements 2 in the pile hole A, and then placing concrete. The inclination angle θ of the pile widened portion is 12 degrees or less as described above, the rising portion h1 is 30 cm or more, the pile bottom rebar amount is 0.4% or more of the pile cross-sectional area, and the number of rebars used is 6 or more. ing. Further, the height h of the pile widened portion is determined by the required bottom area of the pile widened portion.

[0003]

In order to deal with this,
It has been attempted to provide a reinforcing bar in the widened portion of the pile (Japanese Patent Publication No. Sho 49-41848 and Japanese Unexamined Patent Publication No. 58-29917), but all of them have a complicated structure such as using a hinge as a mechanism for expanding the reinforcing bar of the widened portion. There was a problem in workability, and it was also costly. In order to solve the problems of the prior art,
The applicant of the present application has previously proposed, as Japanese Patent Application No. 4-181906, a method of constructing cast-in-place reinforced concrete bottom piles and an invention of a reinforced basket used for this method. Although the problem can be solved, due to the structure of the expansion mechanism of the bottom expansion bar, there is a problem that a large force is required for expansion when uneven external force, especially twisting force is applied to the bottom expansion bar. Became clear. It is an object of the present invention to provide a method for constructing a cast-in-place reinforced concrete bottom pile that solves the problems of the prior art and the prior application, and a reinforced basket used for the method.

[0004]

The present invention has been made to achieve the above object. (1) In a method of constructing cast-in-place reinforced concrete bottom piles, the cast iron is supported on a cylindrical rebar cage located in the pile widening portion. For bottom-expanded piles in which members are radially fixed and radially widened rebars are radially arranged at the same position, and a slide member fixedly mounted at the center of the widened rebar is slidably inserted into the support member. Hanging the rebar cage in the pile hole, expanding the widening part reinforcing bar in the pile hole to the pile hole widening part using a expanding device, and then placing concrete in the pile hole (first invention). (2) In a rebar cage for cast-in-place reinforced concrete bottom piles, a support member is radially fixed to a cylindrical rebar cage located in the pile widening section, and the widening section rebars are radially arranged at the same position to provide the support member. The space fixed to the central part of the widened part rebar Id member slidably and loosely inserted and within pile hole that was so expanding the widened portion rebar Kuiana widened portion (second
Invention) is the gist.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the embodiments shown in FIGS. The reinforcing bar cage for the expanded bottom pile is composed of a cylindrical reinforcing bar cage B and a widening section reinforcing bar C as main members. The cylindrical rebar cage B is a cylindrical shape formed by connecting the main bar 1 and the hoop bar 2, and is arranged on the hoop bar 2 located in the pile widening part of the cylindrical bar B radially at substantially equal intervals. The support member 3 is fixed. The support member 3 slidably supports the slide member 5 fixed to the central portion of the widened portion reinforcing bar C, which will be described later,
The support member 3 is provided with two shaft members 4 constituted by a bearing device having a bearing so that the sliding member 5 slides smoothly and the widened portion reinforcing bar C main body slides horizontally. It is movably installed. In this example,
The loop-shaped L-shaped steel is used for the hoop streak 2 for fixing the support member 3, but the hoop reinforcement 2 is not limited to this and may have any shape as long as the support member 3 can be firmly fixed. It may be one. Further, the number of the fixed support members 3 is the same as that of the widened portion reinforcing bars C, and six pieces are provided in the present embodiment, but four or eight or the like are provided depending on the pile diameter and the bearing capacity of the pile widened portion. It can be set arbitrarily. In addition to the bearing device having the above-mentioned bearing, the shaft member 4 can be configured by loosely inserting a bolt into a through hole formed in the support member 3.

The widened portion reinforcing bar C is such that when the insertion portion 6a, the inclined portion 6b, the rising portion 6c and the widening reinforcing bar C into the cylindrical reinforcing bar cage B are expanded, they are radiated from the axis of the cylindrical reinforcing bar cage B. Reinforcing bar member 6 composed of horizontal portion 6d, and rebar member 6
It is configured by the spacing member 7 that keeps the shape of, and is radially arranged on the cylindrical rebar cage B located in the widened portion of the pile. On this occasion,
In order that the horizontal portions 6d of the reinforcing bar members 6 of the adjacent widened portion reinforcing bars C do not interfere with each other, the levels (height) of the horizontal portions 6d of the reinforcing bar members 6 of the adjacent widened portion reinforcing bars C are slightly different from each other. It is desirable to install it. Therefore, as described above, the number of the widened portion reinforcing bars C to be arranged can be arbitrarily set according to the pile diameter and the ground bearing capacity of the widened portion of the pile, but it is preferable that the number is even. A slide member 5, which is slidably inserted into a support member 3 fixed to a cylindrical rebar cage B, is fixed to the center of the spacing member 7. In this embodiment, two vertically arranged reinforcing bars are used as the slide member 5, but the slide member 5 is not limited to this, and for example, a steel pipe having a square or circular cross section can be used. In this case, it is desirable to provide a shaft member on the support member 3 so as to sandwich the steel pipe from above and below. Further, the spacing member 7 is fixedly provided with a pushing member 8 to which a tip 15 of a first frame 14 of the expansion device D described later is connected.

A stopper for restricting the sliding length of the slide member 5 within the support member 3 so that the widened portion reinforcing bar C surely expands to the pile hole widened portion A1 and maintains the expanded state. Can be provided. The stopper is the support member 3
When the slide member 5 slides in the inside for a predetermined length, the support member 3
By preventing the slide member 5 from sliding inside, the widened portion reinforcing bar C can be surely expanded to the pile hole widened part A1 with the axis of the cylindrical reinforcing bar cage B as a symmetry, and the expanded state can be maintained. Any shape may be used as long as it is such. In this embodiment, when the slide member 5 slides within the support member 3 for a predetermined length, the two rebars of the slide member prevent the slide member 5 from sliding further by coming into contact with the shaft member 4. Member 5a for connecting the ends of the
A stopper is formed by a drop-in member (not shown) provided at the end of the support member 3 that prevents the slide member 5 from sliding in the opposite direction by falling from the upper surface of the reinforcing bar of the slide member 5 to the end surface.

When constructing a cast-in-place reinforced concrete bottom expanding pile using the reinforcing bar cage for bottom expanding pile constructed as described above, the widening portion reinforcing bar C is fixed in the supporting member 3 fixed to the cylindrical reinforcing bar basket B. The rebar cage for expanded bottom pile in which the slide member 5 is loosely inserted is attached to the outer periphery of the cylindrical rebar cage B with the rising portion 6c of the rebar member 6 of the rebar C for widening, that is, the outer diameter of the rebar cage for expanded bottom pile. It is hung down to a predetermined position in the pile hole A in the smallest state, and after expanding the widening part reinforcing bar C in the pile hole A to the pile hole widening part A1 using the expanding device D, concrete is expanded in the pile hole A. To place.

Expanding device D used to expand the widened portion reinforcing bar C
As shown in FIG. 1, the upper fixed ring 1 is attached to the upper end of the shaft tube 9.
0, a first lower fixed ring 11 is provided at the bottom, and an upper fixed ring 10
Sliding ring 1 sliding on the shaft tube 9 between the first lower fixed ring 11 and
The tip 1 of the first frame 14 connected to the upper fixed ring 10 by sliding 2 with the first hydraulic cylinder 13.
5 is configured to be expanded and contracted by a link motion of a link 16 that connects the sliding ring 12 to the sliding ring 12. further,
The expansion device D includes a moving ring 17 below the first lower fixed ring 11.
And a second frame 20 connected to a second lower fixed ring 19 provided below the first lower fixed ring 11 by moving the moving ring 17 up and down by the second hydraulic cylinder 18.
The distal end 21 of the second link 22 is expanded and contracted by the link motion of the second link 22 connected to the moving ring 17. The link 16 is configured such that the length thereof can be finely adjusted by a screw so that the first frame 14 can evenly expand the widened portion reinforcing bar C via the pushing member 8.

Then, on the ground, the second hydraulic cylinder 18 of the expansion device D is operated to operate the second lower fixed ring 19
The front end 21 of the second frame 20 connected to the first frame 14 connected to the upper fixed ring 10 by expanding the distal end 21 of the second frame 20 to connect the expansion device D to the cylindrical rebar cage B and operating the first hydraulic cylinder 13. The tip 15 of the bottom is expanded and slidably connected to the pushing member 8 fixed to the spacing member of the widened portion reinforcing bar C, and then the expanded bottom pile reinforcing bar cage is placed at the predetermined position in the pile hole A as described above. And the first hydraulic cylinder 13 is actuated to further open the tip 15 of the first frame 14 connected to the upper fixed ring 10 to push the pressing member 8 and the spacing member 7.
After widening the widening portion reinforcing bar C to the pile hole widening portion A1 via, the concrete is placed in the pile hole A. In this case, before the concrete is placed in the pile hole A after expanding the widening part reinforcing bar C to the pile hole widening part A1, the first hydraulic cylinder 13
And by operating the second hydraulic cylinder 18, the connection between the tip 15 of the first frame 14 and the sliding member 8 and the connection between the tip 21 of the second frame 20 and the cylindrical rebar cage B are released, and the wire 23 Control device from the ground to expand device D
To collect.

The state in which the widened portion reinforcing bar C is expanded into the pile hole widened portion A1 can be confirmed by installing an underwater camera or various sensors. Further, it is desirable that these underwater cameras and various sensors are installed so that they can be collected after confirmation of the expansion of the widened part reinforcing bar C, like the expansion device D.

[0012]

According to the present invention, in constructing cast-in-place concrete reinforced concrete bottom piles, since reinforcing bars are also provided in the pile widening portions, the shearing force generated by the ground reaction force applied to the pile widening portions causes the concrete in the pile widening portions to be concrete. Also, since it is supported by reinforcing bars, the inclination angle θ of the pile bottom part can be designed to be large, so the height h of the pile widening part can be made smaller than that without reinforcing bars, and the amount of concrete used can be reduced. Therefore, the cost can be reduced. Furthermore, since the expanding mechanism of the simple structure consisting of the supporting member and the sliding member was used to expand the widening part reinforcing bar of the reinforcing bar cage for the expanded bottom pile,
Compared with the expanding mechanism having a complicated structure that conventionally uses a hinge, it has advantages such as better workability and lower cost. In particular, in the present invention, the supporting member is radially fixed to the cylindrical rebar cage located in the pile widening portion, and is fixed to the central portion of the widening portion reinforcing bar radially arranged in the cylindrical rebar cage located in the pile widening portion. Since the installed slide member is slidably inserted into the support member, even if a non-uniform external force, especially a twisting force is applied to the expanded bottom bar, a large force is not required to expand the expanded bar and the expanded bar can be expanded. It can be opened smoothly. Further, since the widened part reinforcing bars can be radially arranged (for example, 6 directions, 8 directions) in the cylindrical reinforcing bar cage and expanded, the widened part reinforcing bars can be arranged over the entire surface of the pile widened part. It is possible to increase the bearing capacity of the widened portion of the pile.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing a method for expanding a reinforcing bar of a widened portion according to the present invention.

FIG. 2 is a cross-sectional view showing a method for expanding the reinforcing bar of the widened portion of the present invention.

FIG. 3 is a vertical cross-sectional view showing the expanded state of the widening bar of the present invention.

FIG. 4 is a perspective view showing a main part of a reinforcing bar cage for a bottom expanding pile according to the present invention.

FIG. 5 is a perspective view showing a cylindrical rebar cage of the present invention.

FIG. 6 is a perspective view showing a main part of a cylindrical rebar cage of the present invention.

FIG. 7 is a perspective view showing a reinforcing bar of the widened portion of the present invention.

FIG. 8 is a vertical cross-sectional view of a conventional bottomed pile

FIG. 9 is a transverse cross-sectional view of a pile widening portion of a conventional bottom spreading pile.

[Explanation of symbols]

 A Pile hole A1 Pile hole widening part B Cylindrical rebar cage C Widening part rebar D Expanding device 3 Supporting member 5 Sliding member

Claims (2)

[Claims] 1. A method of constructing cast-in-place reinforced concrete bottom piles, wherein a supporting member (3) is radially fixed to a cylindrical rebar cage (B) located in the pile widening section, and the rebar section (C) is widened at the same position. ) Are radially arranged, and a slide member (5) fixed to the central portion of the widened portion reinforcing bar (C) is slidably loosely inserted into the support member (3) so as to be slidable. It is hung in the hole (A), and the widened portion reinforcing bar (C) is hung in the pile hole by using the expanding device (D).
A method for constructing a cast-in-place concrete reinforced concrete bottom pile, characterized by placing concrete in the pile hole (A) after expanding to 1). 2. A rebar cage for cast-in-place reinforced concrete bottom piles, wherein a supporting member (3) is radially fixed to a cylindrical rebar cage (B) located in the pile widening section, and the rebar section (C) is located at the same position. Are radially arranged, and a slide member (5) fixed to the central portion of the widened portion reinforcing bar (C) is slidably loosely inserted into the support member (3) and is slidably inserted in the pile hole (A). Reinforcing bar basket for cast-in-place reinforced concrete bottom piles, characterized in that the widened part reinforcing bar (C) is expanded to the pile hole widening part (A1).