JPH04302616A - Crushing of cast-in-place pile and removal of reinforcing steel cage - Google Patents

Abstract

PURPOSE:To extract a reinforcing steel cage in the state of cutting soil pressure by way of changing an existing cast-in-place pile into a hollow pile and crushing its concrete from the inside by means of diameter expansion and to simultaneously prevent breaking of the ground around an extraction hole of the reinforcing steel cage. CONSTITUTION:A cast-in-place pile is changed into a hollow pile by forming a cut hole a in the central part of the cast-in-place pile, and peripheral concrete of the cut hole a is expanded in diameter from the inside and crushed 6. A reinforcing steel cage 2 is extracted by cutting soil pressure by way of burying a casing underground in order to surround a crushed concrete structure and engaging a diameter expansion member 5 with the lower part side of the reinforcing steel cage. Thereafter, the casing 12 is extracted after charging backfilling sand C in the extracted hole.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention provides a method for crushing a cast-in-place pile buried underground and removing a reinforcing bar cage that is inside the pile. Regarding.

0002

[Prior Art] The above-mentioned cast-in-place pile is made by inserting a cylindrical reinforcing bar cage into an underground hole excavated with an earth auger, for example.
It is constructed by pouring concrete into an excavated hole to bury the reinforcing cage.

Conventionally, to remove such cast-in-place piles,
While excavating and lowering a cylindrical casing with a cutting claw at the lower end around the cast-in-place pile, the concrete of the cast-in-place pile is cut with an earth auger, and the embedded reinforcing bar cage is removed with an auger bit. The method is to cut them and remove them to the ground, then pull out the earth auger, put backfilling earth and sand into the removal hole of the cast-in-place pile, and pull out the casing.

0004

[Problems to be Solved by the Invention] However, the main reinforcing bars of reinforcing bar cages are thick, with a diameter of 20 to 25 mm, and it is extremely difficult to cut them with an auger bit. In most cases, the main reinforcing bars of a reinforcing bar cage are tied together in the middle of the reinforcing bar cage, for example, by wires, etc., and when cutting force by an auger bit is applied to the tied part of the main reinforcing bars, that is, to the end side (the tip of the pile The same applies to the initial stage of fracture from the side), no matter how thick the diameter of the main reinforcing bar is, the end side of the main reinforcing bar is bent.
The auger bit has a cutting action that scrapes the peripheral surface of the main reinforcing bar, and subsequent digging is extremely difficult and takes a long time, and the auger bit wears out early, or it becomes impossible to cut and dig at all. Sometimes it became.

On the other hand, since the hoop reinforcement of the reinforcing bar cage is located at a gentle slope with respect to the cutting direction of the auger bit, the auger bit is It acts to cut this hoop line in a so-called surface cutting state, and no matter how thin the diameter is, cutting this is extremely difficult and time consuming. The auger bit wore out prematurely.

[0006] Alternatively, if the reinforcing bars are not cut, the reinforcing bars may become entangled with the auger bit or earth auger, causing the reinforcing bars to rub against the casing, making strange creaking noises, or making it impossible to excavate. At this time, we were often forced to pull out the earth auger and melt the reinforcing bars inside the hole, which was extremely dangerous work.In general, we had to repeatedly break the pile little by little from the tip and remove part of the reinforcing bar cage. This required a long time to remove each cast-in-place pile.

[0007] In view of these circumstances, it is an object of the present invention to provide a method for removing cast-in-place piles in a short time without any of the above-mentioned inconveniences.

[0008]

[Means for Solving the Problems] The method of crushing cast-in-place piles and removing reinforcing bar cages according to the present invention, which has achieved the above object, is to remove the concrete inside the cylindrical reinforcing cage by cutting and removing the cast-in-place piles. A cut hole is formed in the center of the cut hole, the concrete surrounding the cut hole is sequentially crushed from the bottom of the hole upward using a crushing means, and a casing is buried in the ground to surround the crushed concrete structure. , and a diameter-expanding member whose diameter expands as it rotates is plunged into the crushed concrete mass to expand the diameter of the diameter-expanding member, and the diameter-expanding member is locked to the lower side of the reinforcing bar cage to remove the reinforcing bars. The feature is that the cage is pulled out, backfilling soil is poured into the hole formed by pulling out the reinforcing cage, and the casing is then pulled out.

[0009]

[Operation] That is, the cast-in-place piles are turned into hollow piles, which are sequentially crushed from the bottom side, and a casing is placed around the crushed concrete structure, so that the earth pressure against the concrete structure is This method involves cutting the reinforcing bar cage, locking the diameter expanding member on the lower side of the reinforcing bar cage while it is being held, and pulling out the reinforcing bar cage, without cutting the reinforcing bar cage.
The entire reinforcing bar cage, including a part of the concrete mass, can be easily pulled out at once in a state of earth pressure cutting.

[0010] Furthermore, before the casing for earth pressure cutting is pulled out, the inside of the casing is backfilled with earth and sand, so it is ensured that the ground collapses around the pull-out hole when the cast-in-place pile from which the casing has been pulled out has been completely removed. is prevented.

[0011]

[Example] The procedure for crushing cast-in-place piles and removing reinforcing bar cages according to the present invention will be explained below. First, Figure 1 (
As shown in A) and (B), an earth auger 4 equipped with an auger bit 3 having a diameter slightly smaller than the assembled inner diameter of a cylindrical reinforcing bar cage 2 embedded in a cast-in-place pile 1 is used to Cut and remove the internal concrete from step 2 until it penetrates the bottom end of the pile.

When removing the internal concrete by cutting, it is desirable that, for example, the auger bit 1 is equipped with an air or water blowing nozzle to blow high-pressure water or air into the cutting part. As shown in FIGS. 2 and 3, the auger bit 3 is provided with a diameter-expanding member 5 whose diameter increases as the auger bit rotates in a direction opposite to the cutting direction.

Next, the earth auger 4 is pulled out to the ground, and the cast-in-place pile 1 is turned into a hollow pile 1a with a cut hole a formed in the center, as shown in FIG. A crushing means 6 is inserted into the cut hole a of the hollow pile 1a, and the concrete around the cut hole a is sequentially crushed from the bottom of the hole to the top of the pile.

An example of the crushing means 6 is shown in FIG. This crushing means 6 has a reciprocating type hydraulic cylinder 9 installed horizontally at the lower end of a telescoping rod 8 which is extended by pulling out the locking pin 7 and is connected and fixed by the insertion of the locking pin 7. A pressure oil supply hose 10 for the cylinder 9 is inserted into the telescopic rod 8, and a pressing member 11 is provided on the piston rod 9a and cylinder tube 9b of the hydraulic cylinder 9, respectively. The dimension between the outer ends of the pressing member 11 under contraction is slightly smaller than the inner diameter of the cut hole a, and the dimension between the outer ends of the pressing member 11 under extension is larger than the inner diameter of the cut hole a. , the stroke of the hydraulic cylinder 9 is set.

The hollow pile 1a including the reinforcing bar cage 2 is cut by rotating the telescopic rod 8 intermittently, for example, every 60 degrees or every 90 degrees, and expanding and contracting the hydraulic cylinder 9 each time. The concrete around hole a is expanded in diameter and crushed, and this crushing is sequentially carried out from the bottom of the hole by hollow pile 1.
This is done over the upper edge of a.

After confirming the above-mentioned crushing, the crushing means 6
is removed, and as shown in FIG. 1(D), the crushing means 6
A casing 12 is buried in the ground around the concrete structure so as to surround the crushed concrete structure (the reinforcing steel cage 2 and the crushed concrete mass 1b) to cut the earth pressure against the concrete structure. It is.

[0017] Under this earth pressure cut, Fig. 1(E)
As shown in the figure, the earth auger 4 is inserted into the cutting hole a again, and the earth auger 4 is rotated in the cutting direction, so that the auger bit 3 and the diameter expanding member 5 are plunged into the concrete mass 1b. . Then, the earth auger 4 is rotated in a direction opposite to the cutting direction, and the diameter-expanding member 5 is
is expanded in diameter, and this diameter-expanding member 5 is locked to the lower side of the reinforcing bar cage 2.

In this way, the diameter expanding member 5 is attached to the reinforcing bar cage 2.
As shown in FIG. 1(F), the earth auger 4 is pulled up and, under the earth pressure cut by the casing 12, the concrete mass 1b that is partially entangled is removed.
The entire reinforcing bar cage 2, including the reinforcing bar cage 2, is pulled out to the ground from the lower side at once.

This pulling out of the reinforcing bar cage 2 is carried out under the earth pressure cut by the casing 12, so that it is easily carried out. After the reinforcing bar cage 2 is pulled out, and before the earth pressure cutting casing 12 is pulled out, backfilling soil c is thrown into the hole b formed by pulling out the reinforcing bar cage 2.

Next, as shown in FIG. 1 (G), the casing 12 is pulled out, and this completes the crushing of the cast-in-place pile 1 and the removal of the reinforcing bar cage 2. However, before pulling out the casing 12, Since backfilling soil c is thrown into the casing pull-out hole b, the ground collapse around the pull-out hole b is reliably prevented.

[0021]

[Effects of the Invention] As explained above, the method of crushing cast-in-place piles and removing reinforcing bar cages according to the present invention eliminates the problem of premature wear of the auger bit or inability to cut and dig without cutting the reinforcing bar cages. The method involves turning cast-in-place piles into hollow piles, crushing them, and pulling out the entire reinforcing cage, including the concrete mass, all at once while cutting the earth pressure, without causing any damage.Removal of cast-in-place piles can be achieved easily and in a short time.

[0022] Moreover, since the inside of the casing for earth pressure cutting is backfilled with earth and sand before being pulled out, it is reliably prevented from ground collapse even after the removal of the cast-in-place pile from which the casing has been pulled out is completed.

[Brief explanation of the drawing]

FIG. 1A to FIG. 1G are explanatory diagrams showing the procedure for crushing cast-in-place piles and removing reinforcing bar cages.

FIG. 2 is a side view of the lower part of the earth auger in which the diameter of the diameter-expanding member is expanded.

FIG. 3 is a bottom view of the earth auger showing a diameter-expanded state of the diameter-expanding member.

FIG. 4 is a sectional view of the crushing means.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1... Cast-in-place pile, 1b... Concrete lump, 2... Reinforced cage, 5... Diameter expansion member, 6... Crushing means, 12... Casing, a
... Cutting hole, b... Casing pullout hole, c... Earth and sand for backfilling.

Claims (1)

[Claims] Claim 1: Cutting away the concrete inside the cylindrical reinforcing cage to form a cut hole in the center of the cast-in-place pile, and sequentially crushing the concrete around the cut hole from the bottom of the hole upward using a crushing means. Then, a casing is buried in the ground to surround the crushed concrete structure, and a diameter-expanding member that expands in diameter as it rotates is plunged into the crushed concrete mass. The diameter-expanding member is locked to the lower side of the reinforcing bar cage, the reinforcing bar cage is pulled out, backfilling soil is thrown into the hole formed by pulling out the reinforcing bar cage, and the casing is later pulled out. Characteristic methods for crushing cast-in-place piles and removing reinforcing cages.