JPH03183818A - Noiseless disposal of pile head for cast-in-place reinforced concrete pile - Google Patents

Abstract

PURPOSE:To dispose of a pile head without noises by holding a cylinder to the inside of head part of a circular column-shaped reinforcing bar basket, by inserting same into a pile hole with static spalling agents placed around the lower part thereof and by removing concrete inside the cylinder after early curing of the concrete. CONSTITUTION:A cylinder 2 made of a galvanized sheet iron is held inside a circular column-shaped reinforcing bar basket 1 whose top is bent outward, and static spalling agents 4 are attached along the outer periphery of the reinforcing bar basket 1. The reinforcing bar basket 1 is then lowered by hanging into a pile hole 10 and ready-mixed concrete is placed. Then hooks 3 are embedded into unhardened concrete with their tops exposed over the concrete. The static spalling agents 4 swell with hardening of the concrete, making the concrete cracks. The concrete around the pile top is excavated after early curing of the concrete. The concrete on the outside is then eliminated and the concrete block on the inside is also removed by the hooks 3 and then the cylinder 2 is removed.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to an improved method for treating the head of a cast-in-place reinforced concrete pile by removing concrete from the pile head to expose reinforcement after construction.

(Prior Art) In cast-in-place reinforced concrete piles that are widely used as foundation piles for civil engineering and architectural structures, in order to fix the reinforcing bars at the pile head to the main structure, for example, the cast pile concrete undergoes initial hardening. After that, the concrete at the head of the pile is crushed using a concrete breaker, the concrete grain is removed, and the head of the reinforcing steel is exposed.

However, since the work of crushing concrete using a concrete breaker is accompanied by severe vibration and noise, it is becoming increasingly difficult to carry out such work over a long period of time in urban areas or densely populated residential areas.

On the other hand, as a concrete crushing method that does not generate noise or vibration, a static crushing method is known in which a static crushing agent is placed in advance at the location where crushing is required and then concrete is poured. Static crushing agents expand in response to heat generation and moisture during concrete hardening, creating many cracks in the concrete during initial hardening, and crushing the concrete.By removing the crushed concrete grains, Reinforcement bars can be exposed without causing noise or vibration.

(Problem to be solved by the invention) However, even in this static crushing method, the concrete particles inside the reinforcement must be manually removed to avoid damaging the reinforcement, and this work requires a great deal of labor. There was a problem.

Furthermore, in order to crush concrete to a size that can be removed manually, a large amount of crushing agent must be used, resulting in a problem that the cost is higher than the crushing method using a concrete breaker.

The present invention has been made to solve the above problems.
j! ! The purpose is to reduce the amount of crushing agent used and facilitate the removal of concrete shells while taking advantage of the static crushing method's low noise and vibration-free construction.

(a!Means for resolving the issue) For this purpose, the present invention involves inserting reinforcing bars assembled into a columnar shape into a pile hole, and inserting a cylindrical reinforcing bar with a low-adhesive material inside the head of the reinforcing bar. At the same time, a static crushing agent is placed near the lower layer of this cylinder, and concrete is poured into the pile hole. Immediately after pouring, a hook is embedded in the concrete inside the cylinder, and after the concrete has initial hardening, the concrete is placed inside the cylinder. concrete of 7
・The concrete inside the reinforcing bar head is removed by lifting it up via a bar.

(Function) Since the cylinder fixed inside the reinforcing bar head is made of a low-adhesive material, the poured concrete initially hardens without adhering to the cylinder. Additionally, as the concrete initially hardens, the static crushing agent forms cracks near the bottom end of the cylinder. On the other hand, the concrete inside the cylinder is protected by the cylinder from the influence of the static crushing agent, so it hardens as a block.

Therefore, by lifting the concrete inside the cylinder through the hook after the initial hardening of the concrete, this part of the concrete is separated from the pile body through the cracks formed by the crushing agent, and is pulled out of the cylinder as a large lump. removed from the reinforcing bar head. The cylinder will be removed after removing this concrete mass. In this way the pile cap concrete is removed without making any noise or vibration.

(Example) Embodiments of the present invention are shown in FIGS. 1 to 4.

FIG. 1 shows a state in which reinforcing bars 1 assembled in a cylindrical shape are suspended through wire lobes 7 by a crane (not shown) into a pile hole 10 excavated in the ground. As shown in the figure, the head of the reinforcing bar 1 is bent outward, and the cylinder 2 is fitted inside. *In addition, a static crushing agent 4 is installed along the outer periphery of the reinforcing bar 1 on the outside of the cylinder 2.

Yen 1i! 2 is composed of a zinc side iron plate to which concrete does not easily adhere, and is locked inside the head of the reinforcing bar 1 when assembling the reinforcing bar 1.

Similarly, when assembling the reinforcing bars 1, the static crushing agent 4 is attached near the lower end of the circle @2 along the outer periphery of the reinforcing bars 1, and is also attached above it at an appropriate interval. In addition, yen 2
The static crushing agent 4 disposed near the lower layer is previously formed to have a cross-sectional shape of an ellipse that is elongated in the horizontal direction as shown in the figure.

Reinforcement bar 1 with cylinder 2 and static crushing agent 4 attached in this way
is climbed onto a crane and inserted into the pile hole 10, and then fresh concrete is poured into the pile hole 10. Once the concrete has been poured to a predetermined position, the hook 3 is embedded in the uncured concrete inside the cylinder 2 with its head exposed, as shown in FIG.

When the concrete begins to harden in the state shown in Fig. 2, the IP curing agent 4 expands due to the curing heat, causing many cracks to occur in the surrounding concrete that is in the process of hardening, as shown in Fig. NIJ3. However, except for the cracks generated by the static crushing agent 4 at the bottom, these cracks are blocked by the circle @2 and do not propagate inside the circle @2 and only fracture the concrete outside the reinforcing bars 1.

On the other hand, the crack caused by the static crushing agent 4 at the lowermost portion penetrates into the inside of the reinforcing bar 1 beyond just below the bottom end of the cylinder 2.

Since this static crushing agent 4 has an elliptical cross section that is long in the lateral direction, the range in which cracks occur is large in the lateral direction and small in the downward direction.
: Horizontal cracks occur.

Now, once the concrete has initially hardened, the area around the pile head is excavated as shown in FIG. 3, and the concrete outside the reinforcing bars 1 crushed by the static crushing agent 4 is first removed.

Next, the wire robe 7 is hung on the hook 3 embedded inside the cylinder 2 and lifted up by a crane.

Since the concrete inside the cylinder 2 has hardened without being affected by the static crushing agent 4, the concrete in this area is separated from the pile body 5 at the transverse crack formed just below the cylinder 2. Then, as shown in FIG. 4, it is pulled out as one large piece of concrete (i6). It should be noted that since concrete is difficult to adhere to the circle @2 made up of the iron plate on the zinc side, the cylinder 2 remains inside the reinforcing bars 1 as it is, and only the concrete mass 6 is pulled up from the cylinder 2. Therefore, the concrete mass 6 does not come into contact with the reinforcing bars 1 on the outside and can be pulled up without damaging the reinforcing bars 1.

The concrete j116 pulled up in this way is removed as is, and finally the cylinder 2 is removed from the head of the reinforcing bar 1, thereby completing the pile cap treatment.

In addition, the static crushing agent 4 removes the concrete inside the reinforcing bars 1 without crushing it as a lump, so the work is done without generating noise or vibration, and the work requires less labor and time. Since it is only necessary to crush the concrete outside of the reinforcing bar 1 and directly under the circle @2, there is no need to use a large amount as in the case of crushing the entire amount of concrete at the head of the pile.

(Effects of the Invention) As described above, the present invention maintains a cylinder made of a low-adhesive material inside the head of reinforcing bars assembled in a cylindrical shape, and arranges a static crushing agent near the lower end of this cylinder. As a result, the concrete inside the cylinder is separated from the pile body due to the cracks generated by the static crushing agent in the concrete directly under the cylinder, and the concrete inside the cylinder can be removed without crushing it as a large lump. Therefore, there is no noise or vibration caused by the crushing of concrete, and the labor and time required to remove crushed concrete grains and the amount of static crushing agent used can be greatly reduced. Moreover, it can be easily constructed without requiring special machinery or skills.

Therefore, according to the present invention, it is possible to perform pile cap treatment of cast-in-place concrete piles without vibration, without noise, and at low cost.

[Brief explanation of drawings]

MS Figures 1 to 4 all show examples of the present invention; Figure 1 is a longitudinal cross-sectional view of reinforcing bars attached to a cylinder and static crushing material and suspended into a pile hole, and Figure 2 is a diagram showing the loading of ready-mixed concrete. Figure 3 is a vertical cross-sectional view of the pile head, showing how cracks have occurred in the concrete, and Figure 4 is a vertical cross-sectional view of the pile head, showing how the concrete mass is being lifted. FIG. 1... Rebar, 2... Cylinder, 3... Hook, 4...
・Static crushing agent, 10...Pile hole.

Claims (1)

[Claims] A reinforcing bar assembled in a cylindrical shape is inserted into the pile hole, a cylinder made of a low-adhesion material is locked inside the head of the reinforcing bar, and a static crushing agent is placed near the bottom end of the cylinder. Concrete is poured into the pile hole, a hook is embedded in the concrete inside the cylinder immediately after pouring, and after the concrete has initial hardened, the concrete inside the cylinder is lifted up through the hook to remove the concrete inside the reinforcing bar head. A noiseless pile cap treatment method for cast-in-place reinforced concrete piles.