JPH0214491B2 - - Google Patents

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention applies a static load to hollow piles such as steel pipe piles and concrete piles, and the pile This invention relates to a static load type pile press-in method for press-fitting a main body into the ground, and an apparatus therefor.

(Prior art) In particular, as a method for driving hollow ready-made piles such as steel pipe piles and concrete piles into the ground, impact force is applied to the piles such as the drop hammer type, pneumatic type, and vibrating pile drive type. A method of placing it underground,
It can be roughly divided into methods such as pressing the pile into the ground by applying static load. The various impact methods of the former have environmental problems such as noise and vibration, and their application is limited. Another method is the pre-boring method, but it uses a liquid agent to prevent the wall from collapsing, so it has problems such as the need for waste liquid treatment.

On the other hand, the latter static load type press-in method is widely adopted because, compared to the above-mentioned impact construction method, there are no factors that cause problems such as generation of noise, vibration, or environmental pollution.

(Problem to be solved by the invention) The conventional static load type pile press-in method presses the pile into the ground by simply applying a static load, which requires a very large static load, which causes static load generation. This had the disadvantage of increasing the size of the device or drive system. Furthermore, since the piles that are press-fitted into the ground are subjected to circumferential frictional resistance due to the lateral pressure of the soil on the front side, the press-in efficiency decreases, and there are problems such as the need to increase the press-in force accordingly.

(Means for Solving the Problems) Therefore, the present invention relates to a static load type pile press-in method that solves the above-mentioned conventional problems by effectively press-fitting piles into the ground even with a relatively small static load. A hollow cylindrical pile body with an open lower end and a blind member and an air vent near the upper end is erected on the ground,
The pile body is characterized in that the air inside the pile body is discharged from the air vent using a vacuum pump while applying a static load, and the pile body is press-fitted into the ground by the resulting internal reduced pressure and static load. By attaching a sheet material with low frictional resistance to the soil to the inner or outer surface of the pile body and press-fitting it, it becomes possible to reduce the circumferential surface resistance due to the lateral pressure of the soil, improving the press-fitting efficiency.

The apparatus of the present invention for carrying out the above pile press-in method is provided with a blind member and an air vent near the upper end of a hollow cylindrical pile body with an open lower end, and a vacuum pump is connected to the air vent, and the pile The main body is loaded into a press-fitting machine. By attaching a sheet material with low frictional resistance to soil to the inner or outer surface of the pile main body during use, it is possible to reduce the circumferential surface frictional resistance during press-fitting by the pile press-fitting method described above.

(Function) A hollow cylindrical pile body with an open lower end and a blind member and air vent near the upper end is erected, and a static load is applied to the pile body by a static load generator installed in the pile press-in machine. By discharging the air inside the pile body, whose lower end is blocked by the ground and the inside is airtight, using a vacuum pump through the air vent, in addition to the downward pressure input due to the static load, the inside of the pile body is Reduced pressure acts on the pile body. This allows the pile body to be easily press-fitted into the ground even under a relatively small static load.

By attaching a sheet material with low frictional resistance to the soil on the surface of the pile body, it is possible to reduce the peripheral surface frictional resistance due to the lateral pressure of the soil that the pile body receives when press-fitting. As a result, the pile main body can be more easily and reliably pressed into the ground in combination with the static load and the internal reduced pressure, and the pulling resistance during pulling out is also reduced.

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

(Example) Fig. 1 is a block diagram schematically showing a pile press-in device for carrying out the static load type pile press-in method of the present invention, and Fig. 2 is a cross-sectional perspective view of the pile main body.

1 in the figure is a hollow cylindrical pile body such as a steel pipe pile or a concrete pipe pile.

This pile body 1 is the pile chuck 1 of the press-in machine body 10.
It is held fixed at 1. The pile chuck 11 is the support tower 12
It is supported in a vertically slidable manner and is moved vertically by a vertical drive cylinder 13. In particular, the vertical drive cylinder 13 generates a static load for press-fitting the pile body 1 into the ground.

14 is a base of the press-fitting machine main body 10. Fixed clamps 15, 15 are provided at the bottom of this base 14, and these clamps 15, 15 are attached to the existing piles 1',
1' to fix the press-fitting machine main body 10.

The structure of the pile main body 1 according to this embodiment will be explained as follows.
As shown in FIG. 2, this pile body 1 consists of a cylindrical body 2 having an opening 3 at the lower end, and a blind member 4 near the upper end.
is installed. This blind member 4 may be integrally welded to the cylinder body 2, but in this embodiment, the cylinder body 2
A flange 5 is provided on the inner peripheral surface of the flange 5.
It may be fixed by a fastening member 6 such as a bolt or nut. If the blind member 4 is fixed to the cylindrical body 2 with the fastening member 6 in this manner, there is an advantage that the blind member 4 can be removed and reused after the pile main body 1 is press-fitted into the ground.

7 is an air vent formed near the upper end of the pile body 1. In this embodiment, the air vent 7 is provided in the blind member 4, but it may be provided at any position that communicates with the inside of the cylinder 2, for example, it may be formed on the side surface of the cylinder 2.

A vent pipe 8 is removably connected to the vent port 7,
Connect to vacuum pump 9. Therefore, by driving the vacuum pump 9, the air inside the cylinder body 2 is removed from the air vent 7.
and is discharged to the outside via the ventilation pipe 8.

4a is a reinforcing material for the blind member 4. This reinforcing member 4a is not an essential element of the present invention.

Next, a pile press-in method using the pile press-in device having the above configuration will be explained, and further, its operation will be mentioned. To simplify the explanation, when press-fitting piles,
As shown in Figure 1, the press-in machine 10 is installed on the existing pile 1',
The procedure of the press-fitting method will be disclosed below assuming that the pile body 1 is newly press-fitted into the ground adjacently with the pile body 1 installed on top of the pile body 1'.

First, the pile body 1 is inserted into the pile chuck 11 of the press-in machine 10.
The lower end of the pile main body 1 is erected on the ground G by holding it fixedly at the ground G. In this state, the vertical drive cylinder 13 is driven to begin press-fitting the pile body 1 into the ground. At the same time, the vacuum pump 9 connected to the air vent 7 provided near the upper end of the pile body 1 is driven to exhaust the air inside the pile body 1. The pile main body 1 has its lower end open, but at this time the opening 3 is blocked by the ground, so the internal pressure decreases.

This internal reduced pressure becomes a force that attracts the ground by the difference in pressure from the external atmospheric pressure. That is, as a result of the suction force due to the differential pressure, an effect of reducing the internal volume of the cylindrical body 2 acts, and a force that causes the pile body 1 to be buried in the ground is generated.

When the pile body 1 is driven into the ground or press-fitted into the ground, the ground G' surrounded by the inside of the pile body 1 usually sinks due to the pressing force due to a simple static load, but according to the present invention, the ground G' surrounded by the inside of the pile body 1 sinks. Since the internal volume is reduced, the degree of subsidence is reduced, or depending on the geology, subsidence can be completely prevented.

Furthermore, due to the internal pressure reduction of the cylinder body 2, water in the soil is sucked up to the inner peripheral surface of the opening 3 at the lower end of the pile body 1, which reduces the peripheral surface frictional resistance when the pile body 1 is press-fitted. be.

After the pile main body 1 is buried as specified by the above method, the vent pipe 8 is removed and connected to the pile to be press-fitted subsequently. Or the fastening members 6, 6
It is also possible to remove the blind member 4 and attach it to the next pile. Needless to say, once the pile press-in is completed, the pile press-in machine 10 is advanced in the conventional manner in preparation for the next pile press-in.

Furthermore, one of the features of the present invention is that when pulling out an existing pile, if pressurized air is introduced from the air vent pipe 8 and the air vent 7, contrary to the above, the expansion force of the air inside the pile body 1 will cause the pile to be pulled out. It is also possible to reduce the pulling force.

FIG. 3 shows another embodiment of the present invention, in which:
The same symbols as in the above embodiments indicate equivalent elements.

In this embodiment, in order to further reduce the pressing force of the pile body 1, a circumferential friction reducing member 20 such as a sheet material having low frictional resistance against soil is provided on the circumferential surface of the cylindrical body 2. This member 20 is made of a material such as synthetic resin or paper impregnated with lubricating oil.
In particular, the member 20 is sufficiently effective even if it is provided in contact with the outer surface of the cylindrical body 2, but it is also effective if it is attached in a U-shape from the outer surface to the inner surface as shown in FIG. good. Arranging the members 20 in a U-shape in this way not only makes it easier to attach the members 20, but also eliminates the risk of them separating when the pile is press-fitted. In addition, the pile body 1 has better contact with the surrounding soil.
The airtightness of the closed internal space becomes higher.

21 is a bite assisting member. This auxiliary member 21
This is for holding the pile body 1 in the pile chuck 11 of the press-in machine 10 when substantially the entire length of the pile body 1 is buried underground. Conventionally, a special coupling tool was required to attach this auxiliary member 21, but in the present invention, since the blind member 4 is provided, it is sufficient to simply place the auxiliary member 21 on the blind member 4.

In the embodiment shown in FIG. 4, the air vent 7 is connected to the cylinder 2 of the pile body 1.
In this case, the pile body 1 can be press-fitted into the ground by placing a weight 22 on the upper end of the pile body 1 as a static load. The pile main body 1 having this configuration can be easily applied to press-fitting a single pile into the ground, and the weight 22 can be lifted up with a hook 23 of a crane or the like and used for pile press-fitting work as appropriate.

(Effects of the Invention) As explained above, according to the present invention, a pile main body having an open lower end and an air vent near the upper end is erected on the ground, the internal space is closed off, and the internal air is removed from the air vent through the air vent. By applying a static load while venting the pile, the internal decompression acts in combination with the static load as a downward pressure input to the pile body, so even a small static load can be effectively press-fitted. Therefore, the static load generator or the drive system can be downsized, and the press-fitting efficiency can be significantly improved. Furthermore, by attaching or attaching a friction reducing member having low frictional resistance to the soil to the pile main body, the circumferential surface frictional resistance due to the lateral pressure of the soil is reduced, so that the pile pressure input can be further reduced.

[Brief explanation of drawings]

Drawings Fig. 1 is an explanatory diagram showing a schematic configuration of one embodiment of the apparatus for carrying out the static load type pile press-in method according to the present invention, Fig. 2 is a cross-sectional perspective view of the same pile body, and Fig. 3 is an illustration of another embodiment. FIG. 4 is a side sectional view showing a part of the pile main body in yet another embodiment. DESCRIPTION OF SYMBOLS 1...Pile main body, 4...Blind member, 7...Air vent, 9...Vacuum pump, 20...Surface friction reduction member.

Claims (1)

[Claims] 1. A hollow cylindrical pile body with an open lower end and a blind member and an air vent near the upper end is erected on the ground, and a vacuum is connected to the air vent while applying a static load to the pile body. A static load type pile press-in method characterized by driving a pump to reduce the pressure inside the pile body, and press-fitting the pile body into the ground with static load and internal reduced pressure. 2. The static load type pile press-fitting method according to claim 1, characterized in that a circumferential friction reducing member is attached to the surface of the pile body. 3. A blind member is provided near the upper end of a hollow cylindrical pile body with the lower end open, an air vent is provided near the upper end of the pile body or in the blind member, and a vacuum pump is connected to the air vent port. A static load pile press-in device characterized in that the air inside the cylindrical pile main body is exhausted to the outside through the air vent by driving a vacuum pump to reduce the pressure inside the cylindrical pile main body. 4. The static load type pile press-in device according to claim 3, characterized in that a circumferential friction reducing member is attached to the surface of the pile body.