JP6758694B1 - Steel pipe pile - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a steel pipe pile 1 capable of exhibiting a high and stable bearing capacity without being influenced by the soil quality of the surface layer of the ground. SOLUTION: A steel pipe pile 1 has a pile main body 2 rotated around an axis, a tip blade 3 fixed to the tip of the pile main body 2 and rotated together with the pile main body 2 to dig into the ground, and a tip blade 3. A peripheral blade 4 which is fixed to the pile body 2 at a distance in the direction of the base end and rotates together with the pile body 2 to flow earth and sand toward the base end of the pile body 2, and the tip blade 3 and the circumference. It is provided with a sediment compression pipe 5 which is fixed to a pile body 2 between the face blade 4 and is formed of a pipe body in which the inner diameter of the tip end side opening 51 is larger than the inner diameter of the base end side opening 52. [Selection diagram] Fig. 1

Description

The present invention relates to steel pipe piles.

For steel pipe piles, which are the basic materials for civil engineering and construction, it is required to increase the bearing capacity for the ground. For example, Patent Document 1 describes a steel pipe that penetrates into the ground, a cap-shaped member that has an opening for inserting the steel pipe at the upper part and opens downward, and is made of steel that penetrates near the ground surface. The foundation piles equipped with are disclosed. In this foundation pile, the bearing capacity for the ground is enhanced by the cap-shaped member that penetrates near the ground surface.

Japanese Unexamined Patent Publication No. 2012-219484

Since the surface layer of the ground has lower strength than the support layer, it may be difficult to obtain sufficient bearing capacity with the foundation pile of Patent Document 1.
In addition, when the surface layer of the ground is composed of embankment or backfill soil, the strength is uncertain depending on the type of soil, construction conditions, etc., so the foundation pile of Patent Document 1 can obtain the expected bearing capacity. Inconveniences such as not being possible can occur, and design becomes difficult.
Further, in the foundation pile of Patent Document 1, since the cap-shaped member is retrofitted to the steel pipe penetrating into the ground, the fixing method is limited. For example, when a cap-shaped member is welded to a steel pipe, the quality of the welded portion may be inferior to that when welding is performed at a factory because the welding is performed on-site. In particular, since the welding work is performed near the ground surface, the welding worker is forced to perform the welding work in an unreasonable posture, and there is a problem that defects are likely to occur in the welding. As a result, there may be a problem that the bearing capacity assumed at the time of design cannot be obtained.
The present invention has been made in view of such circumstances, and an object of the present invention is to realize a steel pipe pile capable of exhibiting a high and stable bearing capacity regardless of the soil quality of the surface layer of the ground.

In order to solve the above problems, the steel pipe pile according to the present invention is fixed to a pile body that is rotated around an axis and near the tip of the pile body, and is rotated together with the pile body to dig into the ground. The second blade is fixed to the pile body with a space between the blade and the first blade in the direction of the base end, and rotates together with the pile body to flow earth and sand toward the base end of the pile body. A sediment compression pipe fixed to the pile body between the first blade and the second blade and having an inner diameter of the tip end side opening larger than the inner diameter of the base end side opening. The base end side opening of the earth and sand compression pipe is closed by the pile body, and the earth and sand excavated by the first blade is in a compressed state in the inner space of the earth and sand compression pipe. It is configured to be filled, or a gap is formed between the base end side opening of the earth and sand compression pipe and the pile main body to allow earth and sand to pass through. It is characterized in that the first blade is excavated and the compressed earth and sand is discharged in the internal space of the earth and sand compression pipe .

According to the steel pipe pile according to the present invention, it is possible to realize a steel pipe pile capable of exhibiting a high and stable bearing capacity regardless of the soil quality of the surface layer of the ground.

It is a front view of the steel pipe pile of the 1st Embodiment which shown by omitting a part of the pile body. It is a perspective view which looked at the pile body from the tip side. It is a partial cross-sectional view which shows the internal structure of the earth and sand compression pipe. (A) to (d) are diagrams for stepwise explaining the procedure for penetrating a steel pipe pile into the ground. It is a figure which schematically explains the flow of earth and sand at the time of excavation of a steel pipe pile. It is a figure which schematically explains the earth and sand in the earth and sand compression pipe at the time of reaching the support layer. It is a front view of the steel pipe pile of the 2nd Embodiment which shown by omitting a part of the pile body. (A) is a partial cross-sectional view showing the internal structure of the earth and sand compression pipe, (b) is a view of the earth and sand compression pipe seen from the base end side, and (c) is a view of the earth and sand compression pipe seen from the tip side. It is a figure which schematically explains the flow of earth and sand at the time of excavation of a steel pipe pile. It is a figure which schematically explains the earth and sand in the earth and sand compression pipe at the time of reaching the support layer. It is a partial cross-sectional view explaining the modification of the steel pipe pile of 2nd Embodiment. It is a figure explaining the 1st deformation example of the steel pipe pile of 1st Embodiment. It is partial cross-sectional view explaining the 2nd deformation example of the steel pipe pile of 1st Embodiment.

<Outline of steel pipe pile 1>
First, the outline of the steel pipe pile 1 will be described. FIG. 1 is a front view of the steel pipe pile 1 of the first embodiment in which a part of the pile body 2 is omitted, FIG. 2 is a perspective view of the pile body 2 as viewed from the tip side, and FIG. 3 is a sediment compression pipe 5. It is a partial cross-sectional view which shows the internal structure.
The steel pipe pile 1 shown in FIGS. 1 to 3 has a pile body 2 that is rotated around the central axis CA and a tip that is fixed near the tip of the pile body 2 and rotates together with the pile body 2 to dig into the ground. It is fixed to the pile body 2 at a position spaced between the blade 3 (tip blade, first blade) and the tip blade 3 in the direction of the base end, and rotates together with the pile body 2 to collect earth and sand from the pile body 2. The peripheral blade 4 (peripheral blade, second blade) that flows toward the base end and the pile body 2 between the tip blade 3 and the peripheral blade 4 are fixed, and the inner diameter D51 of the tip side opening 51 is fixed. A sediment compression pipe 5 composed of a tapered pipe (tube body) larger than the inner diameter D52 of the base end side opening 52 is provided.

According to the steel pipe pile 1 described above, since the earth and sand compression pipe 5 is fixed to the pile body 2 between the tip blade 3 and the peripheral blade 4, the earth and sand is compressed when penetrating into the ground G (see FIG. 4). The pipe 5 is arranged in the support layer G3 of the ground G together with the tip blade 3 and the peripheral blade 4. The support layer G3 has sufficiently high strength and stable soil quality as compared with the surface layer G1. Therefore, by arranging the earth and sand compression pipe 5 together with the tip blade 3 and the peripheral blade 4 in the support layer G3, the steel pipe pile 1 exhibits a high bearing capacity (particularly, a bearing capacity in the vertical direction). Further, since the strength of the support layer G3 is known, the design of the earth and sand compression pipe 5 and the peripheral blade 4 becomes easy.
Further, in the steel pipe pile 1, a part of the earth and sand excavated by the tip blade 3 flows into the inner space of the earth and sand compression pipe 5 and is compressed, so that a high bearing capacity can be exhibited in this respect as well.
Therefore, according to the steel pipe pile 1, a high and stable bearing capacity can be exhibited regardless of the soil quality of the surface layer G1 of the ground G. Further, since the steel pipe pile 1 can exhibit a high and stable bearing capacity, it is possible to increase the resistance to the shaking of the ground G.

<Steel pipe pile 1 of the first embodiment>
Hereinafter, the steel pipe pile 1 of the first embodiment will be described in detail.
As shown in FIG. 1, the pile body 2 included in the steel pipe pile 1 is, for example, a cylinder having an outer diameter D2 of 165 mm, a thickness t2 of 5 mm, and a length L2 of 1650 mm (10 times the diameter) to 6000 mm (maximum length). It is made of steel pipe of shape. The pile body 2 is not limited to the above dimensions, and may be a square tube (square tube, hexagonal tube, etc.) other than a cylindrical tube, or a solid rod-shaped body.

As shown in FIG. 1, the tip blade 3 is fixed to a position near the tip of the pile body 2 by welding or the like, and rotates about the axis together with the pile body 2. As shown in FIG. 2, the tip blade 3 has a configuration in which two blade members 31 are fixed (welded) to a plate 32 which is a rectangular flat plate made of a rectangular steel plate. The plate 32 is fixed so as to penetrate the central portion of the circular tip surface of the pile body 2, the tip edge thereof protrudes toward the tip from the tip surface of the pile body 2, and both ends in the longitudinal direction thereof are the pile body. It protrudes in the outer diameter direction beyond the outer circumference of the tip surface of 2.
The blade member 31 is made of, for example, a steel plate having a shape obtained by combining a fan shape with a central angle of 90 degrees and a rectangle. For example, the thickness t31 of the blade member 31 is 20 mm, and the maximum turning diameter D3 of the blade member 31 is 396 mm (maximum turning radius R3 = 198 mm), but the dimensions are not limited to these. Further, the shape of the blade member 31 is not limited to this shape as long as it can dig into the ground by rotation.
Each blade member 31 is attached in the opposite direction to both side surfaces of the plate 32, and the pile body 2 is rotated in the forward direction (for example, clockwise when viewed from the base end side) when excavating the ground G. At that time, the ground G is excavated and the earth and sand are inclined so as to be sent upward (base end side).
The fixing position of the tip blade 3 is not limited to the tip of the pile body 2, and may be near the tip of the pile body 2. For example, the blade member 31 may be formed of a spiral strip-shaped steel plate fixed to the outer peripheral surface of the tip of the pile body 2 by welding or the like.

As shown in FIG. 1, the peripheral blade 4 is made of, for example, a spiral strip-shaped steel plate, and is fixed to the outer peripheral surface of the pile body 2 by welding or the like. The peripheral blade 4 rotates about the axis together with the pile body 2 and the tip blade 3, and when the pile body 2 is rotated in the forward direction, the earth and sand excavated by the tip blade 3 flows upward (base end side). ..
The maximum rotation diameter D4 of the peripheral blade 4 is 420 mm, which is larger than the maximum rotation diameter D3 of the tip blade 3. Further, the thickness t4 of the peripheral blade 4 is 12 mm, and the pitch P4 is 150 mm. In the present embodiment, the peripheral blades 4 are attached at a predetermined distance L4 from the base end of the earth and sand compression pipe 5 in the base end direction. In the first embodiment, the distance L4 is 300 mm.
The dimensions of each part of the peripheral blade 4 are not limited to these numerical values, and can be appropriately changed according to the properties of the earth and sand constituting the ground G. Further, the shape of the peripheral blade 4 is not limited to the spiral shape as long as the earth and sand can be flowed to the base end side (upward at the time of excavation) by rotation.

As shown in FIGS. 1 to 3, the earth and sand compression pipe 5 included in the steel pipe pile 1 is made of a steel taper pipe in which the inner diameter D51 of the tip end side opening 51 is larger than the inner diameter D52 of the proximal end side opening 52. ..
Since the base end of the earth and sand compression pipe 5 is fixed to the outer surface of the pile body 2 by welding or the like, the earth and sand compression pipe 5 rotates about the axis together with the pile body 2 and the like. As shown in FIG. 3, the inner diameter D52 of the base end side opening 52 of the earth and sand compression pipe 5 is the same as the outer diameter D2 of the pile body 2, and the base end side opening 52 is closed by the pile body 2. Since the base end side opening 52 is closed by the pile body 2, it is possible to increase the degree of compression of the earth and sand that has flowed into the inner space of the earth and sand compression pipe 5 when the steel pipe pile 1 penetrates into the ground G.

The thickness of the earth and sand compression pipe 5 and the taper angle θ5 are determined based on the physical properties of the earth and sand constituting the ground G. For example, the thickness of the earth and sand compression pipe 5 is set to a thickness that allows the earth and sand constituting the ground G to be inserted. Further, the taper angle θ5 of the earth and sand compression pipe 5 is determined based on the internal friction angle of the earth and sand. By determining the taper angle θ5 of the earth and sand compression pipe 5 based on the internal friction angle of the earth and sand, the earth and sand compression pipe 5 can be smoothly lowered when the steel pipe pile 1 penetrates into the ground G.
In the first embodiment, the thickness t5 of the earth and sand compression pipe 5 is 12 mm, and the taper angle θ5 is 30 ± 5 degrees in consideration of the allowable angle range (± 5 degrees) with respect to the internal friction angle (30 degrees) of the earth and sand. However, it is not limited to these dimensions and angles.

As shown in FIG. 3, the inner diameter D51 of the tip side opening 51 in the earth and sand compression pipe 5 is defined to be equal to or less than the maximum rotation diameter D3 of the tip blade 3. In the present embodiment, the outer diameter of the tip side of the earth and sand compression pipe 5 is set to the same size (396 mm) as the maximum rotation diameter D3 of the tip blade 3, so that the inner diameter D51 of the tip side opening 51 is the maximum rotation of the tip blade 3. It is smaller than the diameter D3 by the thickness t5 of the earth and sand compression pipe 5.
Further, as shown in FIG. 1, the axial position of the base end of the earth and sand compression pipe 5 on the pile body 2 is the position of the maximum rotation diameter D3 of the tip blade 3 along the base end direction from the fixed position of the tip blade 3. It is stipulated in. With this configuration, when the steel pipe pile 1 penetrates into the ground, the earth and sand excavated by the tip blade 3 can be efficiently flowed into the inner space of the earth and sand compression pipe 5. The same effect can be obtained if the axial position of the base end of the earth and sand compression pipe 5 is within the maximum rotation diameter D3 from the fixed position of the tip blade 3.

<Penetration of steel pipe pile 1 into the ground>
Next, the procedure for penetrating the steel pipe pile 1 into the ground will be described.
4 (a) to 4 (d) are diagrams for stepwise explaining the procedure for penetrating the steel pipe pile 1 into the ground, and FIG. 5 is a diagram for schematically explaining the flow of earth and sand during excavation of the steel pipe pile 1. FIG. 6 is a diagram schematically explaining the earth and sand in the earth and sand compression pipe 5 at the time of reaching the support layer G3.
The ground G shown in FIG. 4 has a three-layer structure, and is a surface layer G1, a gravel layer G2, and a support layer G3 in this order from the top. For example, the surface layer G1 is a soft ground, the gravel layer G2 is an aquifer, and the support layer G3 is a strong ground.
As shown in FIG. 4A, when the steel pipe pile 1 penetrates into the ground, the pile body 2 is rotated in the forward direction (for example, in the clockwise direction) with the tip blades 3 arranged near the ground surface. When the steel pipe pile 1 is moved downward while rotating about the axis from the state of FIG. 4 (a), the tip blade 3 digs downward inside the surface layer G1 as shown in FIG. 4 (b). ..

At this time, as shown by an arrow in FIG. 5, the tip blade 3 is embedded in the earth and sand, and the steel pipe pile 1 is dug downward in the ground G (surface layer G1).
A part of the earth and sand excavated by the tip blade 3 flows into the internal space of the earth and sand compression pipe 5 and is compressed. In the steel pipe pile 1 of the present embodiment, as described with reference to FIG. 3, since the inner diameter D51 of the tip side opening 51 in the earth and sand compression pipe 5 is set to be equal to or less than the maximum rotation diameter D3 of the tip blade 3, the steel pipe pile 1 The required amount of earth and sand excavated by the tip blade 3 can flow into the inner space of the earth and sand compression pipe 5 without impairing the excavability.
Further, as shown in FIG. 5, the other part of the earth and sand excavated by the tip blade 3 is relatively excavated along the outer peripheral surface of the earth and sand compression pipe 5 because the steel pipe pile 1 is excavated downward. It flows upward (on the base end side of the pile body 2). This earth and sand also flows relatively upward by the peripheral blade 4. In other words, the peripheral blade 4 receives the resistance of earth and sand to dig the steel pipe pile 1 downward.
Further digging, as shown in FIGS. 4 (c) and 4 (d), the tip blade 3 digs in the support layer G3 after digging the gravel layer G2 downward. When the tip blade 3 reaches the specified depth in the support layer G3, in other words, when the steel pipe pile 1 is penetrated into the ground, the excavation is completed.

By penetrating the steel pipe pile 1 into the ground, the earth and sand compression pipe 5 is arranged in the support layer G3 of the ground G together with the tip blade 3 and the peripheral blade 4. The support layer G3 has sufficiently high strength and stable soil quality as compared with the surface layer G1. Therefore, by arranging the earth and sand compression pipe 5 together with the tip blade 3 and the peripheral blade 4 in the support layer G3, the steel pipe pile 1 exhibits a high bearing capacity in the vertical direction. Since the strength of the support layer G3 is known, it is easy to design the earth and sand compression pipe 5 and the peripheral blade 4.
Further, as shown in FIG. 6, the internal space of the earth and sand compression pipe 5 is filled with the earth and sand ES (G1) of the surface layer G1 and the earth and sand ES (G2) of the gravel layer G2 in a compressed state. Further, the earth and sand ES (G3) of the support layer G3 is also compressed between the earth and sand compression pipe 5 and the tip blade 3. In the steel pipe pile 1, a part of the earth and sand excavated by the tip blade 3 flows into the inner space of the earth and sand compression pipe 5 and is compressed, so that a high bearing capacity can be exhibited in this respect as well. Therefore, according to the steel pipe pile 1, a high and stable bearing capacity can be exhibited regardless of the soil quality of the surface layer G1 of the ground G. Further, since a high and stable bearing capacity can be obtained, the resistance to the shaking of the ground G can be increased.

<Steel pipe pile 1A of the second embodiment>
In the steel pipe pile 1 of the first embodiment described above, the base end side opening 52 of the earth and sand compression pipe 5 is closed by the pile body 2, but the configuration is not limited to this. For example, a gap for passing earth and sand may be formed between the base end side opening 52 of the earth and sand compression pipe 5 and the pile body 2.
Hereinafter, the second embodiment configured in this way will be described. FIG. 7 is a front view of the steel pipe pile 1A of the second embodiment showing a part of the pile body 2 omitted, and FIG. 8 (a) is a partial cross-sectional view showing the internal structure of the earth and sand compression pipe 5A, FIG. 8 (b). ) Is a view of the sediment compression pipe 5A from the base end side, FIG. 8 (c) is a view of the sediment compression pipe 5A from the tip side, and FIG. 9 is a schematic view of the flow of sediment during excavation of the steel pipe pile 1. The figure to be explained and FIG. 10 is a figure schematically explaining the earth and sand in the earth and sand compression pipe 5A at the time of reaching the support layer G3.

In the steel pipe pile 1A of the second embodiment, the pile body 2, the tip blade 3, and the peripheral blade 4 are the same as those of the first embodiment, and thus the description thereof will be omitted.
As shown in FIGS. 7 and 8, in the earth and sand compression pipe 5A included in the steel pipe pile 1A, the inner diameter D51 of the tip end side opening 51 is larger than the inner diameter D52 of the proximal end side opening 52, and the inner diameter of the proximal end side opening 52. D52 is made of a steel taper pipe larger than the outer diameter D2 of the pile body 2.

The base end of the earth and sand compression pipe 5A is fixed to the pile body 2 via the projecting piece 53. The projecting piece 53 is made of a square steel plate, and is fixed to the outer peripheral surface of the pile body 2 by welding or the like.
In the steel pipe pile 1A of the second embodiment, the four projecting pieces 53 are fixed to the outer peripheral surface of the pile body 2 at intervals of 90 degrees in the circumferential direction, but the configuration is not limited to this. For example, the three projecting pieces 53 may be fixed at 120 degree intervals, or the two projecting pieces 53 may be fixed at 180 degree intervals. In short, two or more projecting pieces 53 may be fixed to the outer peripheral surface of the pile body 2 at intervals in the circumferential direction.
At the base end of the earth and sand compression pipe 5A, a plurality of grooves 54 into which each projecting piece 53 is fitted are formed, and in a state where each projecting piece 53 is fitted into each groove 54, the earth and sand compression pipe 5A The base end is fixed to each projecting piece 53 by welding or the like. In the steel pipe pile 1A of the second embodiment, since the base end of the earth and sand compression pipe 5A is fixed to the pile body 2 via the projecting piece 53, the earth and sand compression pipe 5A is rotated around the axis of the pile body 2. Also rotates around the axis.

As shown in FIGS. 8 (b) and 8 (c), in a state where the earth and sand compression pipe 5A is fixed to the pile main body 2, between the inner peripheral surface of the base end side opening 52 and the outer peripheral surface of the pile main body 2 A base end side gap GP for passing earth and sand is formed. The opening area of the base end side gap GP is smaller than the opening area on the tip end side of the earth and sand compression pipe 5A.
As shown by an arrow in FIG. 9, a part of the earth and sand excavated by the tip blade 3 flows into the internal space of the earth and sand compression pipe 5A, is compressed, and is gradually discharged from the base end side gap GP. That is, the earth and sand that has flowed into the earth and sand compression pipe 5A is compressed and replaced as the steel pipe pile 1A penetrates into the ground.
Therefore, as shown in FIG. 10, when the earth and sand compression pipe 5A reaches the support layer G3, the earth and sand ES (G3) of the support layer G3 is filled in the earth and sand compression pipe 5A in a compressed state.
As described above, in the steel pipe pile 1A of the second embodiment, the earth and sand ES (G3) of the support layer G3 can be filled in the internal space of the earth and sand compression pipe 5A in a compressed state, so that a sufficient bearing capacity can be obtained. Therefore, even with the steel pipe pile 1A, a high and stable bearing capacity can be exhibited regardless of the soil quality of the surface layer G1 of the ground G. Further, in the steel pipe pile 1A, the degree of compression of the earth and sand ES (G3) of the support layer G3 can be adjusted according to the opening area of the base end side gap GP.

<Modification example>
Unless otherwise specified, the components, types, combinations, shapes, relative arrangements, etc. described in the respective embodiments are merely explanatory examples, not the purpose of limiting the scope of the present invention to that alone.
FIG. 11 is a partial cross-sectional view illustrating the steel pipe pile 1A'of the modified example of the second embodiment. As shown in FIG. 11, in the modified steel pipe pile 1A', the projecting piece 55 is made of a wedge-shaped steel plate and fixed to the inner peripheral surface of the base end of the earth and sand compression pipe 5A and the pile body 2 respectively. It is different from the steel pipe pile 1A of the second embodiment. The steel pipe pile 1A'of the modified example also has the same action and effect as the steel pipe pile 1A of the second embodiment.

FIG. 12 is a diagram illustrating a steel pipe pile 1'of the first modified example of the first embodiment. As shown in FIG. 12, the steel pipe pile 1'of the first modification is different from the steel pipe pile 1 of the first embodiment in that an excavation blade 56 for excavating the ground G is provided at the tip of the earth and sand compression pipe 5'. It is different. In the steel pipe pile 1'of the first modification, the excavation blade 56 of the earth and sand compression pipe 5'can efficiently excavate the ground G. In the steel pipe pile 1 of the second embodiment, the excavation blade 56 may be provided at the tip of the earth and sand compression pipe 5A.

FIG. 13 is a partial cross-sectional view for explaining the steel pipe pile 1 "of the first modified example of the first embodiment. As shown in FIG. 13, the sediment compression pipe 5B is the tip of the steel pipe pile 1" of the second modified example. It differs from the steel pipe pile 1 of the first embodiment in that it includes a cylindrical portion 57 on the side and a tapered portion 58 on the proximal end side. The steel pipe pile 1 "of the first modification also has the same effect as the steel pipe pile 1 of the first embodiment.
In the steel pipe pile 1A of the second embodiment, the earth and sand compression pipe 5A may be composed of a cylindrical portion 57 and a tapered portion 58.

[Summary of Examples of Embodiments of the Present Invention, Actions, and Effects]
<First embodiment>
The steel pipe piles 1 and 1A according to this embodiment have a pile body 2 that is rotated around an axis, a tip blade 3 that is fixed near the tip of the pile body 2 and rotates together with the pile body 2 to dig into the ground, and a tip. A peripheral blade 4 which is fixed to the pile body 2 with a space between the blade 3 and the pile body 2 and rotates together with the pile body 2 to flow earth and sand toward the base end of the pile body 2, and a tip blade 3 A sediment compression pipe 5, 5A, which is fixed to the pile body 2 between the and the peripheral blade 4 and is composed of a pipe body in which the inner diameter of the tip end side opening 51 is larger than the inner diameter of the base end side opening 52. It is characterized by that.
According to the steel pipe piles 1 and 1A according to this aspect, since the earth and sand compression pipes 5 and 5A are fixed to the pile body 2 between the tip blade 3 and the peripheral blade 4, the earth and sand are compressed when penetrating into the ground G. The pipes 5 and 5A are arranged on the support layer G3 of the ground G together with the tip blade 3 and the peripheral blade 4. Since the support layer G3 has sufficiently higher strength than the surface layer G1 and the soil quality is stable, according to the steel pipe piles 1 and 1A, the support layer G3 has high and stable support regardless of the soil quality of the surface layer G1 of the ground G. Can exert power. Further, in the steel pipe piles 1 and 1A, a part of the earth and sand excavated by the tip blade 3 flows into the inner space of the earth and sand compression pipes 5 and 5A and is compressed, so that the bearing capacity can be enhanced in this respect as well. Further, since a high and stable bearing capacity can be obtained, the resistance to the shaking of the ground G can be increased.

<Second embodiment>
The steel pipe piles 1 and 1A according to this aspect are characterized in that the tips of the earth and sand compression pipes 5 and 5A are circular and the diameter is equal to or less than the maximum rotation diameter of the tip blades 3.
According to the steel pipe piles 1 and 1A according to this aspect, the required amount of earth and sand excavated by the tip blade 3 can flow into the inner space of the earth and sand compression pipes 5 and 5A without impairing the excavability of the steel pipe pile 1. ..

<Third embodiment>
The steel pipe piles 1 and 1A according to this aspect are characterized in that the earth and sand compression pipes 5 and 5A are tapered pipes and the taper angle θ5 is determined based on the internal friction angle of the earth and sand.
According to the steel pipe piles 1 and 1A according to this aspect, the earth and sand compression pipe 5 can be smoothly lowered when the steel pipe pile 1 penetrates into the ground G.

<Fourth embodiment>
In the steel pipe piles 1 and 1A according to this aspect, the axial position of the base end of the earth and sand compression pipes 5 and 5A on the pile body 2 is the maximum rotation of the tip blade 3 along the base end direction from the fixed position of the tip blade 3. It is characterized in that the position is within the diameter D3.
According to the steel pipe piles 1 and 1A according to this aspect, the earth and sand excavated by the tip blade 3 can be efficiently flowed into the inner space of the earth and sand compression pipes 5 and 5A.

<Fifth embodiment>
The steel pipe pile 1'according to this aspect is characterized in that an excavation blade 56 is provided at the tip of the earth and sand compression pipe 5'.
According to the steel pipe pile 1'according to this aspect, the excavation of the ground G can be efficiently performed by the earth and sand compression pipe 5'.

<Sixth Embodiment>
The steel pipe pile 1 according to this aspect is characterized in that the base end side opening 52 of the earth and sand compression pipe 5 is closed by the pile body 2.
According to the steel pipe pile 1 according to this aspect, the degree of compression of the earth and sand flowing into the inner space of the earth and sand compression pipe 5 can be increased.

<Seventh Embodiment>
The steel pipe pile 1A according to this aspect is characterized in that a base end side gap GP through which earth and sand is passed is formed between the base end side opening 52 of the earth and sand compression pipe 5A and the pile body 2.
According to the steel pipe pile 1 according to this aspect, the earth and sand of the earth and sand compression pipe 5A are replaced while being compressed as the steel pipe pile 1 penetrates into the ground, so that when the earth and sand compression pipe 5A reaches the support layer G3. The earth and sand of the support layer G3 can be filled in the earth and sand compression pipe 5A in a compressed state.

1, 1A ... Steel pipe pile, 2 ... Pile body, 3 ... Tip blade, 31 ... Blade member, 32 ... Plate, 4 ... Peripheral blade, 5, 5A ... Sediment compression pipe, 51 ... Tip side opening, 52 ... Base end Side opening, 53 ... Projection piece, 54 ... Groove, 56 ... Excavation blade, θ5 ... Tapered angle of earth and sand compression pipe, G ... Ground, G3 ... Support layer, GP ... Base end side gap

Claims (6)

The pile body that rotates around the axis and
A first blade that is fixed near the tip of the pile body and rotates together with the pile body to dig into the ground.
A second blade fixed to the pile body with a space between the first blade and the pile body and rotating together with the pile body to flow earth and sand toward the base end of the pile body.
An earth and sand compression pipe fixed to the pile body between the first blade and the second blade and composed of a pipe body having an inner diameter of the tip end side opening larger than the inner diameter of the proximal end side opening.
Equipped with a,
The base end side opening of the earth and sand compression pipe is closed by the pile body.
A steel pipe pile characterized in that the inner space of the earth and sand compression pipe is filled with the earth and sand excavated by the first blade in a compressed state . The pile body that rotates around the axis and
A first blade that is fixed near the tip of the pile body and rotates together with the pile body to dig into the ground.
A second blade fixed to the pile body with a space between the first blade and the pile body and rotating together with the pile body to flow earth and sand toward the base end of the pile body.
An earth and sand compression pipe fixed to the pile body between the first blade and the second blade and composed of a pipe body having an inner diameter of the tip end side opening larger than the inner diameter of the proximal end side opening.
Equipped with a,
A gap for passing earth and sand is formed between the base end side opening of the earth and sand compression pipe and the pile body.
A steel pipe pile characterized in that the first blade is excavated from the gap and the earth and sand compressed in the internal space of the earth and sand compression pipe is discharged . The steel pipe pile according to claim 1 or 2, wherein the earth and sand compression pipe is a tapered pipe, and the taper angle is determined based on the internal friction angle of the earth and sand. The axial position of the base end of the earth and sand compression pipe on the pile body is a position within the maximum rotation diameter of the first blade along the base end direction from the fixed position of the first blade. The steel pipe pile according to claim 3. The steel pipe pile according to any one of claims 1 to 4, wherein the outer diameter on the tip end side of the earth and sand compression pipe is the same as the maximum rotation diameter of the first blade. The steel pipe pile according to any one of claims 1 to 5 , wherein an excavation blade is provided at the tip of the earth and sand compression pipe.

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