JPH0412330B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a pile head treatment device for cast-in-place concrete piles used in various structures.

In general, for cast-in-place concrete piles, the concrete is cast at least 50 cm higher than the specified height in advance to prevent floating objects with low specific gravity such as mud from rising after the concrete is placed and reducing the strength of the upper concrete section. After installation, this extra upper concrete portion is removed. Conventionally, as a method for removing this upper concrete portion, a method has been used in which the upper concrete portion is cut off using a rock drill.

However, such chiseling work using a rock drill generates significant noise, vibration, dust, etc., which is becoming a problem as pollution, and the conditions for workers are not favorable in terms of occupational safety and health, resulting in a large amount of damage. There were problems in that it required labor and was economically costly.

In view of these conventional problems, the present inventor has conducted intensive research and has completed a pile cap processing device for cast concrete piles that solves the above-mentioned problems.

Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

In the drawings, reference numeral 1 is a reinforcing steel that forms the framework of cast-in-place concrete. The reinforcing bars 1 extend in the vertical direction and are arranged in a substantially annular manner in large numbers as shown in FIGS. 1 and 2.

Reference numeral 2 denotes a hoop reinforcement, which is wound in a band shape around the outer periphery of the annular reinforcing bars 1, 1, . . . in order to make the reinforcing bars 1 vertical.

3 is a formwork for forming cast-in-place concrete piles. The formwork 3 is formed into a cylindrical shape and has a structure that can be assembled and disassembled as appropriate.

4 and 5 are concrete parts placed in the formwork 3, respectively, 4 is an upper concrete part to be removed after concrete pouring, and 5 is a lower concrete part which is not removed.

6 is a pile head processing device, which includes a destruction pipe 7;
Injection pipe 8, exhaust pipe 9 and joint 1
0, 11, a protective tube 18, an adjustment jig 20, a string 21, etc.

The breaking pipe 7 is for filling with an aqueous slurry of an expandable substance, and is usually made of synthetic resin such as polyethylene or polyvinyl chloride, or in some cases metal. The breaking pipe 7 is arranged in a substantially annular shape near the concrete peripheral surface at the boundary between the upper concrete part 4 and the lower concrete part 5, and is fixed to the entire protective tube 18, which will be described later, with a wire or the like.

Since the breaking pipe 7 is buried in concrete, it has enough strength not to be crushed by the weight of the upper concrete part 4, and has a circular cross-sectional shape.
It has an appropriate shape such as an ellipse. Further, as shown in FIG. 9 or 10, a wedge-shaped fin portion 12 is provided on the outer peripheral surface of the destroying pipe 7.
The destruction pipe 7 is provided protrudingly along the length direction of the pipe 7.
The expansion action causes stress to be concentrated on the fins 12, thereby effectively shearing the concrete. In addition, the diameter of the destruction pipe 7 is 20
It is preferable to set it to 80 mm.

The injection pipe 8 is for injecting a slurry of an expandable substance into the breaking pipe 7, and is connected to the breaking pipe 7 in an upright manner through a joint 10 bent into an L-shape. The injection pipe 8 is the eighth
As shown in the figure, attach the band fitting 1 to the joint 10.
3, and an O-ring 14 is interposed at the connection between the injection pipe 8 and the joint 10 and between the joint 10 and the destruction pipe 7 to prevent muddy water from entering. There is. Moreover, at the upper end 8a of the injection pipe 8,
A cap 15 as shown in FIG. 6 is attached,
Mud water is prevented from entering from the upper end 8a.

Further, the exhaust pipe 9 is for exhausting air so that no air remains in the destruction pipe 7 when filling with the aqueous slurry of the expandable substance, and like the injection pipe 8, it is bent into an L-shape. joint 1
1 is connected to the breaking pipe 7 in an upright manner. The structure of the connecting portion is the same as that of the injection pipe 8 described above, as shown in FIG. A cap 16 as shown in FIG. 7 is attached to the upper end 9a of the exhaust pipe 9 to prevent muddy water from entering through the upper end 9a.

Incidentally, the injection pipe 8 and the exhaust pipe 9 each protrude upward from the upper concrete part 4. Moreover, in FIG. 8, the length L of the connecting portions 10a and 11a of the joints 10 and 11 inserted into the breaking pipe 7 is adjusted as appropriate, so that the length of the breaking pipe 7 can be adjusted. ing. Reference numeral 17 denotes a fin portion protruding from the surface of the joints 10 and 11 corresponding to the fin portion 12 of the breaking pipe 7.

Reference numeral 18 denotes a protective tube, which is made of synthetic resin such as polyethylene or polyvinyl chloride, metal, or the like. The protective cylinder 18 has an appropriate cross-sectional shape with a diameter larger than the diameter of the reinforcing bars 1, and is loosely fitted over the reinforcing bars 1 buried in the upper concrete portion 4, respectively. Note that a reinforcing ring 19 is made of metal, synthetic resin, etc., and is fixed to each protection tube 18 with wire or the like to integrate the protection tubes 18.

Reference numeral 20 denotes an adjustment jig, which is shaped like a long rod and has a cylindrical portion 2 at its lower end that is placed over the upper end of the reinforcing bar 1.
0b, and a hook portion 20a is provided at the upper end.

A string 21 is attached to the adjustment jig 20, and one end is fixed to the upper end of the protective tube 18 of the reinforcing bar 1 to which the adjustment jig 20 is attached, and the other end is attached to the upper end of the adjustment jig 20. It is fixed to the lower end of the protective tube 20 via the hook portion 20a of the lower concrete portion 5 and the hoop reinforcement 2 of the lower concrete portion 5. In other words, the adjustment jig 2
By pulling the string 21 near the hook portion 20a of 0, the destruction pipe 7, injection pipe 8, exhaust pipe 9, and protection tube 18 can be moved up and down.

22 is a hook for lifting the upper concrete part 4 after destruction;
It is buried so as to protrude from the upper concrete portion 4 during pouring.

In addition, the above-mentioned expansive substances include lime-based,
Generally called cement expanding materials such as dolomite type and calcium sulfoaluminate type are used. This expandable substance expands exothermically due to a hydration reaction when mixed with water. For example, Blister (trade name: manufactured by Onoda Cement), which expands exothermically and exhibits an expansion pressure of 200 kg/cm ² or more, is suitable. used for.

Next, a method for removing the upper concrete portion 4 using the pile head processing device 6 will be explained.

First, before placing concrete, each reinforcing bar 1 is covered with a protective tube 18, and the upper end of the protective tube 18 is covered with a reinforcing ring 1.
Fix it to 9 with wire.

The destruction pipe 7 with the injection pipe 8 and the exhaust pipe 9 attached to the lower end of the protection tube 18 is fixed with a wire. At this time, the length of the breaking pipe 7 is adjusted as appropriate using the joints 10 and 11.

In order to move the pile head processing device 6 up and down, an adjustment jig 20 is attached to a plurality of reinforcing bars 1, and a string 21 is tied to the protection tube 18 as shown in FIG.

While pouring concrete into the formwork 3, the height of the concrete pouring reached the breaking pipe 7.
The string 2 attached to the adjustment jig 20 when it gets close
1 is pulled to move the position of the breaking pipe 7 to the boundary between the upper concrete part 4 to be removed and the lower concrete part 5 to be removed after concrete pouring.

Concrete is poured into the formwork 3 to form a cast-in-place concrete pile having an upper concrete portion 4, and hooks 2 are attached to the upper concrete portion 4.
2 is buried so as to protrude from the upper concrete part 4, and the adjustment jig 20 is removed.

Once the concrete has hardened, the formwork 3 is removed, the caps 15 and 16 are taken out, and the aqueous slurry of the expandable substance is filled from the injection pipe 8 into the breaking pipe 7 until it reaches the exhaust pipe 9. Then, as shown in FIG. 4, the breaking pipe 7 expands due to the expansion pressure of the expandable material, and as a result, a crack is generated at the boundary between the upper concrete part 4 and the lower concrete part 5, and the pipe is destroyed. Ru.

Lift the hook 22 by appropriate means,
Remove the upper concrete part 4 (see Figure 5). At this time, since the reinforcing bars 1 are covered with the protective tubes 18, the upper concrete portion 4 can be easily removed.

Furthermore, in the above removal method, the aqueous slurry of the expandable substance is filled into the breaking pipe 7 after concrete is poured, but the aqueous slurry of the expandable substance is filled in the breaking pipe 7 before concrete is poured. The expandable material may be filled in the concrete and expanded after the concrete hardens.

In addition, in the above embodiment, the destruction pipe 7
does not necessarily have to be a continuous ring,
It may have a discontinuous annular shape as long as it can be filled with an aqueous slurry of an expandable substance.

As described in detail above, in the present invention, a breaking pipe is arranged at the boundary between the upper concrete part to be removed and the lower concrete part not to be removed after concrete placement, and the breaking pipe is filled with an expandable substance. Since the boundary portion is destroyed by the expansion pressure of the expandable material, noise, vibration,
The upper concrete part can be easily separated from the lower concrete part without generating dust or the like. Therefore, there is no problem in terms of occupational safety and health for workers, and less labor is required.

Also, one end of the string is fixed to the upper end of the protective cylinder of the reinforcing bar having the adjustment jig, and the other end is fixed to the lower end of the protective cylinder via the hook part of the upper end of the adjustment jig and the hoop reinforcement of the lower concrete part, The position of the breaking pipe can be adjusted up and down by pulling the string, so the breaking pipe can be moved to the specified position while taking into account the pressure of the concrete, the strength of the ground, and the condition of the reinforcing bars when pouring concrete. This enables reliable destruction at the designed boundary between the upper and lower concrete parts. In other words, if the rupture pipe is placed in a fixed position in advance, the height of the reinforcing bars may change due to factors such as the pressure of the concrete and the strength of the ground during concrete pouring, resulting in the rupture pipe being placed in a different position than planned. Therefore, there is a problem in that the concrete cannot be destroyed as designed, and as described above, the present invention solves this problem and allows concrete to be destroyed as designed.

Furthermore, since an expandable substance is used, there is no need for conventional mechanical equipment such as a rock drill, and the destruction work can be carried out simply by filling the destruction pipe with the expandable substance. can.

Furthermore, since the protective tube is loosely fitted over the reinforcing bars in the upper concrete part, the upper concrete part can be easily pulled out from the reinforcing bars when the upper concrete part is removed.

[Brief explanation of drawings]

Fig. 1 is a plan view showing the installed state of the pile head treatment device of the present invention before concrete pouring, Fig. 2 is a partially cutaway front view of the same, and Fig. 3 shows the installed state of the adjustment jig. A partially broken front view, FIG. 4 is a front view showing a cast-in-place concrete pile destroyed by the pile head treatment device of the present invention, and FIG. 5 is a front view showing the cast-in-place concrete pile with the upper concrete portion removed. Figure 6 is a vertical cross-sectional view of the cap attachment part of the injection pipe, Figure 7 is a vertical cross-sectional view of the cap attachment part of the exhaust pipe, and Figure 8 is a state where the injection pipe or exhaust pipe is connected to the destruction pipe by a joint. FIG. 9 is a sectional view showing one embodiment of the rupturing pipe, and FIG. 10 is a sectional view showing another embodiment of the rupturing pipe. 1...Reinforcement bar, 2...Hoop bar, 3...Formwork, 4
... Upper concrete part, 5 ... Lower concrete part, 6 ... Pile head processing device, 7 ... Destruction pipe, 8 ... Injection pipe, 9 ... Exhaust pipe, 1
0, 11... joint, 12, 17... fin, 18... protection tube, 20... adjustment jig, 21...
…string.

Claims (1)

[Claims] 1. When forming cast-in-place piles, a rupture pipe filled with an expandable substance is arranged in a nearly circular shape near the boundary between the upper concrete part that should be removed after concrete placement and the lower concrete part that will not be removed. An injection pipe and an exhaust pipe are connected to each end of the destruction pipe by joints in an upright manner, and each vertical reinforcing bar in the upper concrete part is covered with a protective tube, and the protective tube is integrated with the destruction pipe, and the above-mentioned A long adjustment jig is attached to a plurality of the reinforcing bars in an upright manner, one end of a string is fixed to the upper end of the protective tube of the reinforcing bar that has the adjustment jig, and the other end is attached to the hook at the upper end of the adjustment jig. This is a pile head processing device for cast-in-place concrete piles, which is fixed to the lower end of the protection tube through the hoop reinforcement in the lower concrete section, and the position of the breaking pipe can be adjusted vertically by pulling the string.