JPS5843523B2 - Method for reducing pile head excess concrete of cast-in-place piles - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention makes it possible to reduce excess concrete at the pile head of cast-in-place piles as much as possible while ensuring the quality of the concrete at the top of the pile, thereby reducing costs by reducing the amount of concrete. This paper proposes a method for reducing pile head excess concrete of cast-in-place piles, which is effective in reducing the head disposal cost by reducing the amount of excess concrete pile and is also effective in solving noise problems caused by prayer work. .

For example, in cast-in-place piles using the earth drill method, etc., underwater concrete (C) is cast in bentonite muddy water, so it is necessary to ensure the quality of concrete at the top of the pile.
As shown in FIG. The current situation is that

As a result, not only did the amount of concrete increase, but the cost of the work was also high, and in urban areas, this work was also a source of noise problems.

The method of the present invention solves these problems,
A casing with a drainage hole on the side is set so that the drainage hole is at the same height as or near the top of the set pile, and underwater concrete is poured into the excavated hole, and the concrete is placed at the top of the concrete. It is characterized in that as it rises, concrete mixed with slime overflows from the drainage hole into a drainage pit excavated next to the casing.

According to the method of the present invention, concrete mixed with slime flows out from the drainage hole on the side of the casing.
The height and condition of the top of the concrete placed in the excavation hole can be visually confirmed, and as a result, the excess concrete at the head of the bed (the height from the set top of the pile to the bottom edge of the drainage hole) can be checked as much as possible. Although the concrete quality at the top of the pile is reduced, it is possible to ensure the quality of the concrete at the top of the pile, and depending on the conditions, it is also possible to substantially eliminate excess concrete by aligning the lower edge of the drainage hole with the top of the set pile.

Therefore, the amount of concrete required is small, material costs, transportation costs, etc. can be reduced, and the amount of extra concrete used during subsequent excavation is zero or small, reducing pile head treatment costs. Noise problems caused by construction can be prevented from occurring.

EMBODIMENT OF THE INVENTION Hereinafter, one embodiment of the method for reducing excess concrete pile at the head of a cast-in-place pile according to the present invention will be described based on the drawings.

As shown in Fig. 2A, a casing 2 with an appropriate amount of drainage holes 1 drilled on its side is installed so that the lower edge of the drainage holes 1 is at a distance (for example, several to several tens of crIl) from the top of the pile P. Set it in the upper position, prevent the collapse of the hole wall on the surface side with the casing 2, and prevent the deep hole wall with bentonite slurry, and drill the hole 3 to a predetermined depth using the earth drill method, and the drilling is completed. Thereafter, the slime 4 is allowed to settle after a predetermined period of time (for example, about 30 minutes).

Next, as shown in FIG. 2, packet B is used to perform slime processing (bottom scraping).

In the figure, 5 is a bentonite mud water injection pipe.

Thereafter, as shown in FIG. 2C, the reinforcing bars 6 are suspended and the tremie tube 7 is inserted.

In this state, a water jet is injected at the bottom of the excavation hole 3 for several tens of seconds using a pressure pipe (not shown) to stir and suspend the slime remaining after treatment and the slime that has settled over time after treatment.

In the figure, 8 is a drainage pipe.

Next, as shown in FIG. 2, concrete C is poured using the tremie pipe 7.

When an appropriate amount of conc IJ-) C has been cast, as shown in Fig. 2 E, excavate the side of the casing 2 with a jumbo packet 9, below the drainage hole 1 and below the lower end of the casing 2. A shallow drainage pit 10 is formed.

The bentonite muddy water flowing out from the drainage hole 1 is sucked up to a suitable place on the ground by putting a sand pump SP into the drainage pit 10.

This suction is concrete (concrete mixed with slime).

)C! Do this until you can see it. Next, as shown in Fig. 2, when additional concrete C is placed, as the top of concrete C rises, slime and slime-containing concrete IJ-1-C' are gradually pushed up from drainage hole 1. It overflows into the drainage pit 10.

The overflowing slime and concrete c% are pumped up using Yumbo Packet 9, and the height and condition of the top of the concrete are visually checked. After confirming that the top of the concrete is concrete with a small amount of slime mixed in, concrete is poured. end.

After that, as shown in Figure 2, a plywood board 11 is placed to prevent the top of the concrete from being damaged by backfilling earth and sand.
etc., and backfill the drainage pit 10.

In this state, leave it for an appropriate period of time (about 1 day), cut the edges of the casing 2, pull it out as shown in Fig. 3 parts of the excavated hole are backfilled with earth and sand 12.

According to the above configuration, the height and condition of the concrete top can be visually confirmed, so even if the excess concrete σ is made thinner, the quality of the concrete at the pile top can be ensured.

Therefore, the amount of concrete can be reduced, and as shown in the second diagram, the amount of concrete used during excavation can also be reduced.

In addition, the casing 2 is provided with a plurality of drainage holes 1 in advance at appropriate intervals in the vertical direction, which are closed by removable lids.
may be configured to use

[Brief explanation of the drawing]

1A and 1B are side sectional views showing a conventional example, and FIGS. 2A and 2B are vertical sectional views showing an embodiment of the present invention. 1...Drain hole, 2...Casing, 4
...Slime, 10...Exhaust 4 pits,
C...Concrete.

Claims (1)

[Claims] 1. Place a casing with a drainage hole on the side so that the drainage hole is at the same height as or near the top of the set pile, and pour underwater concrete into the excavated hole, A method for reducing excess concrete on the pile head of a cast-in-place pile, characterized by causing concrete mixed with slime to overflow from the drainage hole into a drainage pit excavated next to the casing as the pile rises.