JP2001020270A - Ground vibration compaction method and equipment therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a ground compaction method and equipment therefor capable of efficiently vibrate the ground without lowering vibration transmission efficiency and also capable of performing ground compaction efficiently at a high drainage efficiency. SOLUTION: A vibrator supporting rod 10 holding a ground compaction vibrator 11 at the bottom end portion is inserted to the ground, the vibration compaction equipment is operated to vibrate the ground, the excess pore water generated by the vibration is drained through a drain pipe 18 arranged along the supporting rod 10. In this case, a water absorbing chamber capable of accepting the inflow of excess pore water is provided in the supporting rod 10, pressure is reduced therein, the excess pore water flows into the water absorbing chamber, and stored water is discharged through a drain pipe 18.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for compacting a soft ground which is liable to be liquefied by vibration, such as a sandy ground or a ground with a lot of fine grains, by vibrating with a vibrator.

[0002]

2. Description of the Related Art Generally, as a method of compacting soft ground,
A method of inserting a vibrator into the ground to be compacted, compacting by applying vibration to the ground, and discharging excess pore water generated by liquefaction due to vibration through a drain pipe inserted along the rod Is known (JP-A-4-272314).

[0003]

In such a conventional method, a drain pipe is provided along the outer periphery of a support rod, a lower end thereof is used as a suction port, and a vacuum pump or compressed air provided on the ground is provided. However, since excess pore water accumulated around the vibrator is discharged using a pump or the like that uses high-pressure jet water, drainage cannot be performed unless excessive pore water is accumulated around the vibrator, and Once
If excess pore water accumulates around the vibrator, the vibration transmission efficiency from the vibrator to the ground will be extremely reduced, and there will be a gap around the vibrator after draining, making it difficult to recover the vibration transmission efficiency. .

[0004] In view of the above problems, the present invention can discharge excessive pore water generated by vibration without collecting around the vibrator, vibrates the ground efficiently without lowering the vibration transmission efficiency, and achieves high vibration. An object of the present invention is to provide a ground compaction method and a ground compaction method capable of effectively compacting the ground with drainage efficiency.

[0005]

A feature of the method according to the present invention for solving the above-mentioned conventional problems and achieving the intended object is that a vibrator holding a vibrator for ground compaction is provided. A ground vibration compaction method of inserting a support rod into the ground, operating the vibrator to vibrate the ground, and draining excess pore water generated by the vibration through a drain pipe arranged along the support rod, The support rod is provided with a water absorption chamber into which the excess pore water can flow, the pressure in the water absorption chamber is reduced, the excess pore water flows into the water absorption chamber, and the water accumulated in the water absorption chamber is discharged through the drain pipe. It is to have done.

Further, the features of the device according to the present invention include a vibrator for compacting the ground, a vibrator support rod that holds the vibrator and is inserted into the ground, and an installation along the vibrator support rod. And a drain pipe for discharging excess pore water, wherein the vibrator support rod has a water absorption chamber into which the excess pore water can flow, and a drain pump is installed in the water absorption chamber. The drain pump is connected to the lower end of the drain pipe, and is provided with a pressure reducing means for reducing the pressure in the water absorbing chamber.

The pressure reducing means comprises a pressure reducing tank communicating with the upper end of the drainage pipe, and a vacuum pump for reducing the pressure in the pressure reducing tank, and is provided with a drainage means for discharging water from the pressure reducing tank. Preferably, the water absorption chamber is provided with a water level sensor capable of detecting an internal water level.

[0008]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 schematically shows an apparatus for carrying out the method of the present invention, in which 1 is a pile driver, 2 is a vibro hammer suspended along a guide post 3 of the pile driver 1, and 4 is a vibro hammer. This is a compacting device that is suspended by being gripped by a second gripping portion 2a.

As shown in FIGS. 2 to 4, the compacting device 4 has a hollow support rod 10 using a steel pipe, and a vibrator 11 for compaction is provided at a lower end of the support rod 10.
Is supported. Around the lower end of the support rod 10, fins 12 for guiding into the ground are radially protruded, while a jet nozzle 13 is installed downward,
High-pressure water for ground excavation is supplied to each jet nozzle 13 through a high-pressure pipe 14.

A lower end portion of the support rod 10 is a water absorption chamber 16 having a large number of fine holes 15 formed in a peripheral wall. A drainage pump 17 composed of a submersible sand pump is accommodated in the water absorption chamber 16. It is drained through. The drain pipe 18 is led out from the upper end through the inside of the support rod 10.

A plurality of water level sensors 19 having different heights are installed in the water absorption chamber 16 to detect that the water level in the water absorption chamber 16 is lower than a predetermined low water level and higher than a predetermined high water level. I can do it.

The interior of the water absorption chamber 16 is decompressed by a decompression means 20. As shown in FIG. 5, the decompression means 20 has a decompression tank 21 serving also as a water reservoir. The pressure in the decompression tank 21 is reduced by a vacuum pump 22 and the interior is opened to the atmosphere. A decompression release valve 23 for releasing the depressurized state is provided. A drain pipe 18 is communicated with the upper part of the decompression tank 21, and the inside of the tank 21 is depressurized.
The pressure in the chamber 6 is reduced. In the decompression tank 21, a drain pump 24 composed of a sand pump is housed at the bottom, and a water level sensor 25 is installed. When the water level in the tank 21 reaches a certain level or more, the drain pump 24 is activated to activate the tank. The water in 16 is drained.

Next, a description will be given of a method of compacting a soft ground by using the apparatus having the above-mentioned structure.

First, the support rod 10 is lowered in a state of being suspended by the vibratory hammer 2, and jet water for excavation is jetted from the jet nozzle 13 as required, and the vibratory hammer 2 is operated to activate the compaction device 4. Insert into the ground.

After the vibrator 11 reaches a desired depth, the operation of the vibro-hammer 2 and the jetting of jet water are stopped, and the compaction vibrator 11 is operated to apply vibration to the ground. At the same time, the pressure inside the water absorbing chamber 16 is reduced by reducing the pressure inside the pressure reducing tank 21. By applying vibration to the ground in this way, the ground is compacted, and at the same time, the surroundings of the vibrator are liquefied and excessive pore water is generated. At this time, since the inside of the water absorbing chamber 16 is in a depressurized state, excess pore water is sucked into the water absorbing chamber 16 from the pores 15 on the peripheral wall and is stored in the chamber.

In this manner, when the water level in the water absorption chamber 16 rises and the water level sensor 19 on the high water level detects the water level, the drain pump 17 in the water absorption chamber 16 is operated, and the water in the water absorption chamber 16 is discharged from the ground. It is discharged into the pressure reducing tank 21. Decompression tank 2
1, when the water level reaches a certain level or more, the water level sensor 25
Detects this, activates the drain pump 24 in the tank 21, and discharges the water in the tank 21.

The operation of each of the drain pumps 17 and 25 is stopped when the water level sensor detects that the water level is below a certain level.

In the present method, the water absorbing chamber 16 is kept in a decompressed state, so that liquefaction occurs due to ground vibration by the vibrator 11 and, when excessive pore water is generated, the water is quickly sucked into the water absorbing chamber 16, The vibrator 11 is discharged without being accumulated around the vibrator 11, and no void is formed around the vibrator after flowing into the water absorbing chamber 16.
Vibration is transmitted to the ground without lowering the vibration transmission efficiency from the ground.

In the above-described example, the pressure in the water suction chamber is reduced through the drain pipe 18. However, an exhaust pipe dedicated to reducing the pressure may be provided and communicated with the pressure reducing tank, and the pressure may be reduced by the vacuum pump.

[0020]

As described above, in the method and the apparatus according to the present invention, the supporting rod is provided with the water absorbing chamber into which excess pore water can flow, and the pressure in the water absorbing chamber is reduced to remove the excess pore water. The water collected in the suction chamber is discharged through the drainage pipe, and liquefaction occurs due to ground vibrations caused by the vibrator. Water is quickly sucked into the water absorption chamber and discharged without accumulating around the vibrator, and there is no gap around the vibrator after flowing into the water absorption chamber. Vibration is transmitted to the ground without lowering, and efficient vibration compaction is performed.

The pressure reducing means comprises a pressure reducing tank communicating with the upper end of the drainage pipe, and a vacuum pump for reducing the pressure in the pressure reducing tank, and is provided with a drainage means for discharging water from the pressure reducing tank. With one drain pipe,
Drainage and decompression in the suction chamber can be performed together,
The device is simplified.

Further, the water absorption chamber is provided with a water level sensor capable of detecting the water level in the interior, so that the operation of the drain pump can be performed only when necessary and automation is possible.

[Brief description of the drawings]

FIG. 1 is a side view schematically showing an example of an apparatus for carrying out the method of the present invention.

FIG. 2 is a side view showing an example of the compacting device of the present invention.

FIG. 3 is a partial longitudinal sectional view of the same.

FIG. 4 is a sectional view taken along line AA in FIG.

FIG. 5 is a piping diagram showing an example of a pressure reducing means of the above device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Pile driver 2 Vibro hammer 2a Gripping part 3 Guide support 4 Compaction device 10 Support rod 11 Vibrator 12 Fin 13 Jet nozzle 14 High pressure piping 15 Pores 16 Water absorption chamber 17 Drain pump 18 Drain pipe 19 Water level sensor 20 Decompression means 21 Decompression tank 22 Vacuum pump 23 Decompression release valve 24 Drain pump 25 Water level sensor

Continuing on the front page (72) Osamu Hirabayashi, Inventor Goyo Construction Co., Ltd. 2-2-2 Koraku, Bunkyo-ku, Tokyo (72) Inventor Yukio Kisara 1-3-6 Uchisaiwaicho, Chiyoda-ku, Tokyo F-term in niche (reference) 2D043 CB03 DA04 EB02 EB06

Claims (4)

[Claims] 1. A vibrator supporting rod holding a vibrator for compacting the ground is inserted into the ground, the vibrator is operated to vibrate the ground, and the excess pore water generated by the vibration is supported by the vibrator. A ground vibration compaction method for draining water through a drain pipe arranged along a rod, comprising: a water absorption chamber into which the excess pore water can flow into the support rod; and depressurizing the water absorption chamber to flow the excess pore water into the water absorption chamber. Wherein the water collected in the water absorbing chamber is drained through the drain pipe. 2. A vibrator for compacting the ground, a vibrator support rod that holds the vibrator and is inserted into the ground, and a drainage pipe installed along the vibrator support rod for discharging excess pore water. In the ground vibration compaction apparatus comprising: the vibrator support rod, a water absorption chamber into which the excess pore water can flow, a drainage pump is installed in the water absorption chamber, and the drainage pump is provided with the drainage pipe. A ground vibration compaction device comprising a decompression means for connecting a lower end portion and depressurizing the water absorbing chamber. 3. The decompression means comprises a decompression tank communicating with an upper end side of a drain pipe, and a vacuum pump for depressurizing the interior of the decompression tank, and includes a drain means for discharging water from the decompression tank. The ground vibration compaction device according to claim 2. 4. The ground vibration compaction device according to claim 2, wherein the water absorption chamber is provided with a water level sensor capable of detecting an internal water level.