JPH0559721A - Head end treating method for cast-in-place pile - Google Patents

Abstract

PURPOSE:To remove head end unnecessary-concrete smoothly in an ingot state, from a cast-in-place pile. CONSTITUTION:On the way of placing concrete for a cast-in-place pile 1, at a boundary between a head end left section and an unnecessary section, the filling injecting pipe 4 of crushing agent is set. Besides, the full lengths on the upper sides from the injecting pipe, of respective vertical reinforcements 3' are covered with cover members 6 for enabling the reinforcements to be drawn upward, and after that, the concrete is placed, and with the expansion of the crushing agent to be worked after the lapse of a set time, the injecting pipe is widened. The section of the injecting pipe to be set to be embedded in is cut off, and an upper side concrete ingot-shaped object on a cutting line is removed upward, and the vertical reinforcements are exposed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for treating a portion of a cast-in-place pile that does not require a head end.

[0002]

2. Description of the Related Art Conventionally, for example, a foundation footing is formed at the head end of a cast-in-place concrete pile. Therefore, a treatment method for removing unnecessary portions of the head end is to leave the remaining portion on the head end side of the pile during the concrete pouring. And the injection pipe of the crushing agent is arranged in the unnecessary part and the boundary, and it is buried in the pouring concrete.

The buried injection pipe is expanded by a crushing agent that expands after a lapse of a set time after the injection (the slit is formed in the injection pipe to make it easy to expand the diameter), and then cast in place. Crush the buried part of the pile head injection pipe.

[0004]

According to the above-mentioned crushing method, the crushing force of concrete due to the expansion of the crushing agent is larger in the circumferential direction than in the axial direction due to the connection between the concrete and the longitudinal bars arranged. Since it works, the outer periphery of the cast-in-place pile collapses in the shape of a groove, and unnecessary concrete at the pile head end remains connected to the vertical streaks. For this reason, it is necessary to carry out chiseling work using a shocking impact tool, and noise problems occur due to the use of the impacting shock tool.

Further, there is a problem in that it takes a lot of time to recover the concrete pieces destroyed by the impact tool.

Further, since the reinforcing bar is damaged during the chipping work, there is a problem that the strength is lowered when the exposed reinforcing bar is used for the reinforcing bar of the basic footing.

SUMMARY OF THE INVENTION An object of the present invention is to provide a head end processing method capable of easily separating a head end unnecessary portion of a cast-in-place pile without using an impact tool.

[0008]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention provides a crushing agent for pushing up concrete that does not require hardening in the boundary between the remaining portion of the head end and the unnecessary portion during the concrete casting of a cast-in-place pile. The injection pipe is arranged to be supported by the vertical stirrup, and the entire length of each vertical streak above the injection pipe is covered by a cover member that can be pulled out upward, and then concrete is placed and set. After the passage of time, the crushing agent that acts after expansion cuts the part of the concrete that uses the injection pipe as a boundary, and the cover member is removed upward together with the concrete block above the cutting line to expose the longitudinal streaks. This is the method of treating the pile head end.

In addition, during the concrete casting of the cast-in-place pile, a hollow pipe having a closed end located on the outer periphery of the pile is supported by a vertical bar across the axis line in the boundary between the head end remaining portion and the unnecessary portion. , The vertical length of each of the vertical pipes is covered with a cover member capable of pulling out the entire length above the hollow pipe, and then concrete is poured, and then the hardened concrete is poured into the hollow pipe portion. It is a method of applying the head end treatment method of cast-in-place piles by striking and splitting it at right angles to the axis, removing the covering member together with the cracked concrete block above to expose the vertical streaks. is there.

[0010]

[Operation] When the set time elapses after the concrete is poured, the filling and crushing agent in the buried injection pipe expands to expand the diameter of the injection pipe and destroys it. It acts and pushes up the hardened concrete above the buried pouring pipe due to the non-bonding of the longitudinal streaks and the covering member. For this reason, the portion of the injection pipe at the pile head end is cut at a substantially right angle to the axis.

The cut concrete block is removed upward together with the covering member to expose the vertical streaks.

After the cast concrete is hardened, the lower end of the cover member of the cast-in-place concrete pile or the portion above the lower end is divided at right angles to the axis by machine or human power.
Then, the cracked upper concrete block is removed upward together with the covering member to expose the vertical streaks.

[0013]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

(First Embodiment) 1 shown in FIG. 1 is a cast-in-place pile.

The cast-in-place pile 1 is excavated from the ground to a predetermined depth in the ground by a known method, for example, an excavator (only an earth auger or a combination of a casing and an earth auger) is used. Then, the rebar cage 3 is inserted into the drilled hole 2 that has been excavated, and then concrete is poured into the drilled hole 2.

While pouring the concrete to form the cast-in-place pile 1, as shown in FIG. 1, an injection pipe 4 for the crushing agent A is arranged in the boundary between the head end remaining portion and the head end unnecessary portion, and a reinforcing bar basket is provided. The injection pipe 4 is supported via the wire 5 on the vertical line 3 ′ of 3.

Further, the entire upper length of each vertical streak 3'from the injection pipe 4 is covered by a covering member 6 which can be pulled out upward.

As shown in FIG. 3, the cover member 6 is formed by dividing a styrofoam cylindrical body into the same number as the number of vertical stripes 3 ', and extends from one end to the other end of the cover member 6. While piercing the vertical line 3 ′ (the vertical line 3 ′ may be inserted into the recessed hole 7 with the enlarged diameter slit 21 which is formed in advance from one end face to the other end of the covering member 6 and is easy to insert), The facing edges of the covering member 6 are overlapped.

After that, concrete is poured.

After a lapse of a set time after the concrete is poured, the crushing agent A expands to expand the diameter of the injection pipe 4 (slits 8 are provided on the peripheral wall of the hard synthetic resin pipe for easy expansion of the diameter). ), So that the portion of the hardened concrete that uses the injection pipe 4 as a boundary is cut.

The above cutting is perpendicular to the axis of the cast-in-place pile 1. Then, the upper concrete block B cut as shown in FIG. 4 is extracted upward.

The method for removing the concrete block B is as follows.
Wrap the wire of a heavy machine around the periphery of the concrete block B,
Pull up by winding the wire.

At this time, since the concrete block B and the vertical streak 3'are not joined by the cover member 6, the concrete block B can be smoothly pulled out, and the cover member 6 is pulled out together to vertically. The muscle 3'is exposed.

As shown in FIG. 2, the odd number of covering members 3
If the winglets 10 are circumscribed on the even-numbered covering members 6 by projecting the winglets 10 on both side surfaces or on the outer corner edges of the winglets, the vertical streaks 3'are slightly pushed outward in the direction of concrete placement. Even if it is removed, the concrete inside and outside the cover member 6 is separated.

As shown in FIG. 2, the injection pipes 4 are bent and arranged in an annular shape having different diameters, and the inner injection pipe 4 and the outer injection pipe 4 are connected by a connecting fitting 12. Sometimes used side by side.

The above-mentioned crushing agent A is described in JP-A 2-1.
As disclosed in Japanese Patent No. 6213, for example, calcium alumino ferrite, free calcium oxide and magnesium oxide are used as basic components, and borate is added as a retarder. Then, the generation time of the hydration expansion pressure can be adjusted by appropriately changing the type and amount of the retarder added.

(Second Embodiment) As in the case of the first embodiment, during the concrete pouring during the formation of the cast-in-place concrete 1,
A required number of pipes 11 having both ends closed (for example, closed by squeezing a plug or the like) are arranged so as to cross the axis in a field between the head end remaining portion and the head end unnecessary portion.

The pipe 11 is made of a hard synthetic resin or the like, and the closed end thereof is positioned on the outer periphery of the cast-in-place pile 1 as shown in FIG. It is supported by 3 '.

Further, a covering member 6 is put on the entire length of each vertical line 3'above the pipe 11 in the same manner as in the first embodiment.

Then, concrete is poured.

After the cast concrete is hardened, first the end of the pipe 11 is exposed, and then a wedge is driven into the end of the pipe to divide the head end at a right angle to the axis.

The cut upper concrete block B is removed upward as in the first embodiment to expose the vertical streaks 3 '.

[0033]

[Effect] As described above, by using the method for treating the head end of the cast-in-place pile according to the present invention, the diameter of the injection pipe and the wedge driven into the pipe cause the remaining portion and the unnecessary portion of the pile head end. The boundary is cut, and the cut upper concrete lumps should be removed very smoothly because the covering member that covers the vertical bars and the concrete so that the vertical bars can be pulled upwards is blocked by the covering member. You can

Therefore, the pile head end can be treated in an extremely short time, and the cost can be remarkably reduced.

[Brief description of drawings]

FIG. 1 is a front view of a cast-in-place pile according to a first embodiment.

FIG. 2 is a sectional view taken along line XX of FIG.

FIG. 3 is a perspective view of a cover member.

FIG. 4 is a front view with the vertical stripes exposed.

FIG. 5 is a partially cutaway enlarged front view showing a main part of the second embodiment.

FIG. 6 is a plan view of the above.

[Explanation of symbols]

 A Crushing agent B Concrete block 1 Cast-in-place pile 2 Drilling hole 3 Reinforcing bar cage 3'Vertical bar 4 Injection pipe 5 Wire 6 Covering member 11 Pipe

Claims (2)

[Claims] 1. An injection pipe for a crushing agent for pushing up concrete that does not require hardening is arranged in the boundary between the remaining portion of the head end and the unnecessary portion while the concrete is being cast into a cast-in-place pile, while being supported by a vertical bar.
In addition, the vertical length of each of the vertical lines is covered with a covering member capable of pulling out the entire length above, and then concrete is poured, and after the set time elapses, the crushing agent acts to expand the concrete. A method for treating the head end of a cast-in-place pile, in which the part with the injection pipe as a boundary is cut, and the covering member is removed upward together with the concrete block above the cutting line to expose the vertical streaks. 2. A hollow pipe having a closed end located on the outer periphery of the pile is supported by a vertical bar while crossing the axis in the field between the head end remaining portion and the unnecessary portion during the concrete casting of the cast-in-place pile. ,
The vertical length of each of the vertical bars is covered with a cover member capable of pulling out the entire length above from the hollow pipe, and then concrete is poured into the hollow pipe. Hit and split at right angles to the axis,
A method for treating the head end of a cast-in-place pile in which the cover member is removed upward together with the cracked concrete block to expose the vertical streaks.