JP2003293364A - Method for constructing pile - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for constructing a pile in which a large number of blades are not required as seen in a multiblade pile and a large bearing capacity is obtained in a soft ground. <P>SOLUTION: An intermediate pile 1 having a blade 3 on an outer periphery on the front end side and a cylindrical outer pile 2 being shorter than the pile 1 and having spiral blades 4 and 5 on an outer periphery on the front end side and the outer periphery on the base end side are used. The intermediate pile 1 is rotated and pressed into the soft ground 6, and the outer pile 2 is rotated and pressed in so as to be formed in a concentrical shape to the pile 1. The outer pile 2 is rotated reversely while its depth is fixed, soil in a section upper than the spiral blade 5 is sent into a lower section by the spiral blade 5 for the outer pile 2 while soil upper than the spiral blade 4 is fed into a lower section by the spiral blade 4 for the outer pile 2, and soil is compressed between the front end blade 3 for the pile 1 and the spiral blade 4 for the pipe 2 and a lump-shaped compressed section 7 is formed. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for constructing a pile for supporting a building or the like, and more particularly to a method for constructing a pile which can be effectively used for soft ground having a deep support layer.

[0002]

2. Description of the Related Art Conventionally, multi-blade piles have been used when it is difficult to drive the piles to the support layer due to the depth of the support layer in soft ground and therefore due to the limit of capacity of construction machines. Has been. However, the multi-blade pile has a problem that a large number of blades must be attached to the outer peripheral portion of the pile shaft, resulting in high manufacturing cost.

In view of the above conventional problems, the present invention provides a method for constructing a pile which does not require many blades such as a multi-blade pile and can obtain a large supporting force on soft ground. The challenge is to provide.

[0004]

[Means for Solving the Problems] The above-mentioned problems are as follows: a middle pile provided with blades projecting laterally on the outer circumference on the tip side, and an outer circumference on the tip side having an inner diameter larger than the outer diameter of the middle pile. Using a cylindrical outer pile with spiral wings protruding laterally, the inner pile was driven into the ground by rotational press-fitting, and then the outer pile was rotationally press-fitted into the ground so as to be concentric with the medium pile. Drive the outer pile with the tip side spiral blade of the outer pile at a predetermined height above the tip blade of the middle pile in the ground, and stop the driving of the outer pile. , By rotating it in reverse while fixing the depth, the soil above the tip of the spiral wing of the outer pile is sent downward, and between the tip wing of the middle pile and the tip spiral of the outer pile. It is solved by a method of constructing a pile, which is characterized by compressing the soil in the area.

According to this method, the blades provided on the middle pile and the outer pile can obtain the supporting force even on soft ground, and the outer pile can be driven in reverse after being driven. Since the soil in the area between the tip blade of the middle pile and the tip side spiral blade of the outer pile is compressed, a very large bearing force can be obtained by compressing the ground in this area.

In the above method, the outer pile is provided with a spiral blade projecting laterally on the outer periphery of the base end side, and the driving of the outer pile is stopped in a state where the base end side spiral blade penetrates into the ground. However, it is also possible to send the soil above it downward by the spiral blade on the base end side by the reverse rotation of the outer pile.

In this case, the soil above the tip side spiral blade of the outer pile can be smoothly fed into the region between the tip blade of the middle pile and the tip side spiral blade of the outer pile. It is possible to effectively compress the region between the tip blade of the and the tip side spiral blade of the outer pile.

If the soil above the base side spiral blade of the outer pile is lost while the outer pile is rotated in the reverse direction, replenish the soil above the base side spiral blade of the outer pile. For example, the frictional force between the outer peripheral surface of the outer pile and the ground in the region between the base side spiral blade and the front side spiral blade of the outer pile is not reduced.

The pitch of the blades on the base end side of the outer pile is made larger than the pitch of the blades on the tip end side of the outer pile, and the region between the base end spiral blade and the tip end spiral blade of the outer pile is rotated during the reverse rotation of the outer pile. Greater bearing capacity can be obtained if the soil is to be compressed.

According to this method, the number of blades can be reduced as compared with the case of the conventional multi-blade pile, the cost of the pile can be kept low, and also in the construction, The pile and the outer pile can be driven in using the same rotary press-fitting machine, and the outer pile can be rotated in the reverse direction with the same rotary press-fitting machine, and construction can be performed without increasing the cost. You can

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Next, an embodiment of the present invention will be described with reference to FIGS.

As shown in FIG. 1, the pile used in the construction method of this embodiment comprises an intermediate pile 1 and an outer pile 2.

The intermediate pile 1 is made of a steel pipe, and a wing 3 protruding laterally is integrally provided on the outer periphery of the tip end side thereof. The blade 3 may be a spiral blade or a blade having a bottom expanding function that does not depend on a spiral. Further, the middle pile 1 is not limited to the steel pipe, and may be made of shaped steel or solid material.

The outer pile 2 is also made of steel pipe, but its inner diameter is designed to be larger than the outer diameter of the middle pile 1 so that the middle pile 1 can be inserted inside the outer pile 2. It is like this. Then, spiral blades 4 and 5 having the same spiral direction are integrally provided at upper and lower two locations of the outer periphery on the base end side and the outer periphery on the tip end side of the outer pile 2, and the length dimension of the outer pile 2 is
It is designed to be shorter than the middle pile 1 and the middle pile 1 is inserted inside the outer pile 2 so that the base end height position is the same height position. 4 is located in the middle of the middle pile 1 in the longitudinal direction, and the tip side spiral blade 4 and the tip blade 3 of the middle pile 1 are designed to be spaced by a predetermined dimension. In the outer pile 2, the spiral blades 4 and 5 on the front end side and the base end side have the same spiral direction.

Construction of piles on the soft ground 6 having a deep support layer is carried out as follows using the above-mentioned middle pile 1 and outer pile 2. That is, as shown in FIG. 2A, first, the soft ground 6
On the other hand, the outer stake 2 is rotationally press-fitted with a rotary press-fitting machine such as a building column car and driven.

Next, as shown in FIGS. 2B and 3C, the outer pile 2 is driven into the ground 6 by rotary press-fitting so as to be concentric with the middle pile 1, and FIG. (D)
As shown in FIG. 3, the base side spiral blades 5 of the outer piles 2 penetrate into the ground, and the tip side spiral blades 4 of the outer piles 2 have a predetermined height dimension below the tip wings 3 of the underground piles 1. The driving of the outer pile 2 is stopped with a space above. The direction of rotation of the outer pile 2 is the direction in which the spiral blades 4 and 5 bite into the ground 6.

Thereafter, as shown in FIG. 4 (e), the outer pile 2 is reversely rotated while fixing the depth thereof. As a result, as shown by the arrow in the figure, the spiral blades 4 and 5 on the tip side and the base end side of the outer pile 2 send soil from the top to the bottom by their spiral feeding function, The soil 7 in the region between the tip blade 3 of the pile 1 and the tip spiral blade 4 of the outer pile 2 is compressed. At that time, the soil 8 above the spiral blade 5 on the base end side of the outer pile 2 is fed downward by the reverse rotation of the outer pile 2 and is reduced, so that the soil 9 for supply is prepared around the pile. However, it is better to replenish the reduced amount.

As a result, as shown in FIG. 4 (), the region between the tip blade 3 of the middle pile 1 and the tip side spiral blade 4 of the outer pile 2 bulges outward more than the blades 3, 4. A bump-shaped compression portion 7 is formed. A very large supporting force can be obtained by this hump-shaped bulging compression section 7.

Moreover, regarding the region 10 between the proximal spiral blade 5 and the distal spiral blade 4 of the outer pile 2, the proximal spiral blade 5 is provided.
Since the soil 9 is replenished by the soil 9, the frictional force between the outer peripheral surface of the outer pile 2 and the ground 6 in the area 10 does not decrease. In addition, the pitch of the base end side spiral blade 5 of the outer pile 2 is set to the outer pile 2
If the pitch is larger than the pitch of the tip side spiral wing 4 of the above, and the soil 10 in the region between the base side wing 5 of the outer pile 2 and the tip side wing 4 is compressed during the reverse rotation of the outer pile 2. , A larger supporting force can be obtained. Of course, a large supporting force can be obtained by the blades 3, 4, 5 as well.

Thus, according to the above pile construction method,
A large supporting force can be obtained even in the soft ground 6 having a deep supporting layer, and the number of blades can be reduced as compared with the conventional multi-blade pile, that is, three blades are sufficient,
The cost of piles can be kept low. Further, also in construction, it is sufficient to drive the inner pile 1 and the outer pile 2 by using the same rotary press-fitting machine, and moreover, the outer pile 2 can be driven by the same rotary press-fitting machine.
Can be rotated in reverse and construction can be performed without increasing the cost. Further, since the pile has a so-called double inner / outer structure, it is possible to obtain a large resistance force against a horizontal force.

Although the embodiment of the present invention has been described above, the present invention is not limited to this, and various modifications can be made without departing from the spirit of the invention. For example, in the above embodiment, the case where the outer pile 2 is provided with two spiral blades is shown, but the number may be one on the tip side, or three or more, or two or three. Even when the number is three or more, the number of blades can be reduced as compared with the case of the multi-blade pile. Further, in the above-described embodiment, the case where the soil 9 is replenished during the reverse rotation of the outer pile 2 is shown, but the blades 5 on the base end side of the outer pile 2 are positioned at a position deep to some extent from the ground. In such a case, soil 9 will be left after the reverse rotation of the outer pile 2 is completed.
May be replenished, or may not be replenished if there is no need for replenishment.

[0022]

EFFECTS OF THE INVENTION Since the present invention is as described above, a large supporting force can be obtained on soft ground without requiring many blades such as a multi-blade pile.

[Brief description of drawings]

FIG. 1 is a side view of a pile used in a construction method of an embodiment.

2A and 2B are side views sequentially showing a construction method together with FIGS. 3 and 4. FIG.

3 (c) and FIG. 3 (d) are side views sequentially showing the construction method together with FIG. 2 and FIG.

4 (e) and FIG. 4 (e) are side views sequentially showing the construction method together with FIG. 2 and FIG.

[Explanation of symbols]

1 ... Middle pile 2 ... outer pile 3 ... Tip wing 4 ... Spiral blade on the tip side 5 ... Spiral blade on the base side 6 ... Soft ground 7 ... Hub-shaped compression part 9… Soil for replenishment

Claims (3)

[Claims] 1. A middle pile provided with blades protruding laterally on the outer circumference on the tip side, and a spiral blade having an inner diameter larger than the outer diameter of the middle pile and projecting laterally on the outer circumference on the tip side. Using the provided cylindrical outer pile, drive the middle pile into the ground by rotary press-fitting, then drive the outer pile into the ground by rotary press-fitting so that it is concentric with the middle pile, and the tip of the outer pile The driving of the outer piles is stopped with the side spiral blades spaced a predetermined height above the tip blades of the inner piles in the ground, and then the outer piles are rotated in reverse while fixing the depth. By doing so, the soil on the tip side of the outer pile is sent downward, and the soil in the area between the tip blade of the middle pile and the tip side of the outer pile is compressed. A method of constructing a pile, which is characterized in that. 2. The outer pile is provided with a spiral blade projecting laterally on the outer periphery of the base end side thereof, and driving of the outer pile is stopped in a state where the base end side spiral blade has entered the ground, The method for constructing a pile according to claim 1, wherein the soil above the outer spiral pile is fed downward by the spiral blade on the base end side by the reverse rotation of the outer pile. 3. The method for constructing a pile according to claim 2, wherein soil is replenished above the base side spiral blade while the outer pile is rotated in the reverse direction.