JP2022012839A - Outer shell steel pipe concrete pile - Google Patents

Abstract

To provide an outer shell steel pipe concrete pile which can exhibit stable deformability and bearing force and which has good workability.SOLUTION: An outer shell steel pipe concrete pile 1 comprises a pile body part 2 formed by concrete. The outer shell steel pipe concrete pile 1 comprises a cylindrical steel pipe part 4 arranged outside the pile body part 2. The outer shell steel pipe concrete pile 1 comprises a reinforcing bar 7 arranged to surround the outer peripheral surface of the steel pipe part 4. Local buckling of the steel pipe part 4 can be suppressed and deformability and bearing force can be improved and workability is excellent.SELECTED DRAWING: Figure 1

Description

The present invention relates to an outer shell steel pipe concrete pile in which a tubular steel pipe portion is provided on the outside of a pile body portion formed of concrete.

An outer shell steel pipe concrete pile called an SC pile has a structure in which the outside of a cylindrical pile main body formed of concrete is covered with a cylindrical steel pipe portion. In such an outer shell steel pipe concrete pile, generally, only the steel pipe portion is made of steel, and the steel pipe portion is thickened in order to increase the yield strength. However, such a fracture form of the outer shell steel pipe concrete pile is often a cross-sectional defect due to peeling of the pile main body (concrete) on the compressed side, and in such a case, local buckling occurs in the steel pipe, and the steel pipe is buckled. Deformation performance and proof stress as designed may not be obtained.

For example, an outer shell steel pipe concrete pile in which a tension steel material (PC steel material) is arranged along an axial direction in a pile main body is known (see, for example, Patent Documents 1 and 2). In the case of these configurations, although the horizontal strength can be improved, it is not easy to prevent the concrete constituting the pile main body from peeling off because the tension steel material is thin and its lateral rigidity is small.

Further, there is known an outer shell steel pipe concrete pile that can suppress the expansion of cracks even if cracks occur in the concrete pile main body by providing a ridge on the inner surface of the steel pipe portion (see, for example, Patent Document 3). .. However, it is difficult to prevent buckling of the steel pipe by simply providing a ridge on the inner surface of the steel pipe, and although it is possible to delay the expansion of cracks and the progress of peeling in the pile body, it is finally possible. When a part of the pile body part peels off from the steel pipe part to create a gap between the pile body part and the pile body part moves into the pile hollow part filled with the pile circumference fixing liquid and excavated earth and sand, the pile bearing capacity increases. There is a risk that the pile will decrease sharply and the pile will bend sharply.

Furthermore, high-strength concrete mixed with a swelling agent is lined inside the steel pipe to form a cylindrical pile body, and the hollow part of the pile body is filled with concrete such as expandable concrete to fill the outer shell steel pipe. Concrete piles are known (see, for example, Patent Document 4). In this configuration, although a part of the pile body can be peeled off from the steel pipe, the inner pile body can be prevented from moving into the pile hollow part filled with the pile circumference fixing liquid and excavated earth and sand, but the pile is piled up before construction. If filled concrete is placed in the hollow part to make a pile without the hollow part of the pile, construction becomes difficult because the earth and sand do not pass through the hollow part of the pile.

Jitsukosho No. 53-29363 Gazette Jikkai Sho 58-10938 Gazette Japanese Unexamined Patent Publication No. 61-207716 Jikkenhei 3-76031 Gazette

As described above, there is a demand for an outer shell steel pipe concrete pile that has stable deformation performance and yield strength and is easy to construct.

The present invention has been made in view of such a point, and an object of the present invention is to provide an outer shell steel pipe concrete pile which can obtain stable deformation performance and proof stress and has good workability.

The outer shell steel pipe concrete pile according to claim 1 is arranged so as to surround a pile main body formed of concrete, a tubular steel pipe portion arranged outside the pile main body portion, and an outer surface of the steel pipe portion. It is provided with a reinforcing body.

The outer shell steel pipe concrete pile according to claim 2 is the outer shell steel pipe concrete pile according to claim 1, and includes axial reinforcements embedded along the axial direction at a plurality of locations around the central axis of the pile main body. It is a thing.

The outer shell steel pipe concrete pile according to claim 3 is the outer shell steel pipe concrete pile according to claim 2, and the axial reinforcing body is arranged at the center of the thickness of the pile main body portion.

The outer shell steel pipe concrete pile according to claim 4 is the outer shell steel pipe concrete pile according to claim 2, wherein the axial reinforcing body is arranged in contact with the inner surface of the steel pipe portion.

The outer shell steel pipe concrete pile according to claim 5 is the outer shell steel pipe concrete pile according to any one of claims 1 to 4, wherein the steel pipe portion is formed in a cylindrical shape, and the reinforcing body is formed on the outer peripheral surface of the steel pipe portion. It is formed in an annular shape along it.

According to the present invention, the reinforcing body resists local buckling of the steel pipe portion, stable deformation performance and proof stress can be obtained, and workability is improved.

(A) is a cross-sectional view showing an outer shell steel pipe concrete pile according to the first embodiment of the present invention, and (b) is a vertical cross-sectional view showing an outer shell steel pipe concrete pile. Same as above It is a graph which shows the relationship between the deformation performance and the proof stress of the example corresponding to the outer shell steel pipe concrete pile, and the comparative example corresponding to the conventional example. (A) is a cross-sectional view showing an outer shell steel pipe concrete pile according to a second embodiment of the present invention, and (b) is a vertical sectional view showing an outer shell steel pipe concrete pile. (A) is a cross-sectional view showing an outer shell steel pipe concrete pile according to a third embodiment of the present invention, and (b) is a vertical cross-sectional view showing an outer shell steel pipe concrete pile.

Hereinafter, the first embodiment of the present invention will be described with reference to the drawings.

In FIGS. 1 (a) and 1 (b), 1 indicates an outer shell steel pipe concrete pile. The outer shell steel pipe concrete pile 1 is also called an SC pile. In order to clarify the explanation, the outer shell steel pipe concrete pile 1 will be simply referred to as a pile 1 below. Further, in FIG. 1B, the pile 1 shows only one end side, but the other end side is also formed in the same manner.

The pile 1 includes a pile main body 2. The pile body 2 is formed of concrete into a cylindrical shape. That is, the pile main body portion 2 has a hollow portion 3 on the central side. The hollow portion 3 communicates with both ends of the pile main body portion 2 in the axial direction. A steel pipe portion 4 is arranged on the outside of the pile main body portion 2. The steel pipe portion 4 is also referred to as an outer shell steel pipe. The steel pipe portion 4 is formed into a cylindrical shape by a steel plate.

Further, end plates 5 are provided at both ends of the pile main body 2 and the steel pipe 4 in the axial direction. The end plate 5 is a flat plate-shaped steel plate, and its inner side surface is arranged in contact with the axial end portions of the pile main body portion 2 and the steel pipe portion 4. The end plate 5 has an opening 6 formed at the center thereof. The opening 6 communicates with the hollow portion 3 of the pile main body 2. In the present embodiment, the opening 6 is formed in a circular shape having a diameter dimension equal to or substantially equal to that of the hollow portion 3.

Further, a reinforcing reinforcing bar 7 which is a reinforcing body is arranged on an outer peripheral surface which is an outer surface of the steel pipe portion 4. The reinforcing bar 7 is a linear steel material, a processed steel material having a predetermined width such as a strip, or the like. The reinforcing reinforcing bar 7 is arranged so as to surround the outer peripheral surface of the steel pipe portion 4. In the present embodiment, the reinforcing reinforcing bar 7 is formed in an annular shape (ring shape) along the outer peripheral surface of the steel pipe portion 4. That is, the reinforcing reinforcing bar 7 is formed in an endless shape in which both ends of the linear steel material are connected to each other. The reinforcing reinforcing bars 7 are arranged in a direction orthogonal to or substantially orthogonal to the axial direction of the pile main body portion 2 and the steel pipe portion 4. Further, the reinforcing bar 7 is fixed to the outer peripheral surface of the steel pipe portion 4 by welding or the like. The reinforcing reinforcing bar 7 protrudes in the radial direction from the outer peripheral surface of the steel pipe portion 4.

In the present embodiment, a plurality of reinforcing reinforcing bars 7 are arranged in the axial direction of the pile main body portion 2 and the steel pipe portion 4. The reinforcing reinforcing bars 7 are arranged at equal intervals or substantially equal intervals in the axial direction of the pile main body portion 2 and the steel pipe portion 4. Further, in the present embodiment, the reinforcing reinforcing bar 7 is not arranged at the position of the end plate 5. That is, the reinforcing reinforcing bars 7 are arranged at positions other than both ends of the steel pipe portion 4.

Then, when manufacturing the pile 1, end plates 5 are fixed to both ends of the steel pipe portion 4, concrete is poured inside the steel pipe portion 4, and the pile main body portion 2 is formed by centrifugal compaction or the like. do. The reinforcing bar 7 may be welded to the outer peripheral surface of the steel pipe portion 4 after forming the pile main body portion 2, or the reinforcing reinforcing bar 7 may be welded to the outer peripheral surface of the steel pipe portion 4 in advance and then the pile main body portion 2 is formed. You may.

As a result, the pile main body portion 2 which is a concrete layer is integrally formed inside the steel pipe portion 4 and the end plate 5, and the pile 1 in which the reinforcing reinforcing bars 7 are arranged on the outer peripheral surface of the steel pipe portion 4 is completed.

As described above, according to the first embodiment, since the reinforcing reinforcing bar 7 is arranged so as to surround the outer peripheral surface of the cylindrical steel pipe portion 4 arranged outside the pile main body portion 2 formed of concrete, the steel pipe portion 4 is arranged. It can resist the local buckling of concrete, improve the bending performance, and improve the toughness. Therefore, even in the behavior during an earthquake under high axial force, stable deformation performance (load-deformation) that suppresses the decrease in proof stress (load) after the maximum proof stress (maximum load) and causes little decrease in proof stress even if deformation progresses. Relationship) and proof stress can be obtained. For example, as shown in FIG. 2, in the comparative example corresponding to the conventional example, when the deformation amount increases and reaches the maximum proof stress (maximum load) F, the proof stress sharply decreases with the progress of the subsequent deformation. On the other hand, in the embodiment corresponding to the present embodiment, the decrease in the proof stress against the progress of deformation is suppressed even after the maximum proof stress F is reached.

Further, since the central portion of the pile main body portion 2 is a hollow portion 3, it is possible for earth and sand to pass through the hollow portion 3 when constructing using the pile 1, and good workability is obtained. be able to.

Further, since the steel pipe portion 4 is formed in a cylindrical shape and the reinforcing reinforcing bar 7 is formed in an annular shape along the outer peripheral surface of the steel pipe portion 4, the steel pipe portion 4 has a shape in which local buckling is less likely to occur, and the steel pipe portion 4 has a shape. Reinforcement can be applied uniformly or substantially uniformly over the entire circumference.

Next, the second embodiment will be described with reference to FIG. The same configurations and operations as those of the first embodiment are designated by the same reference numerals, and the description thereof will be omitted.

The pile 1 of the present embodiment shown in FIGS. 3A and 3B includes, in addition to the pile 1 of the first embodiment, an axial reinforcing bar 8 which is an axial reinforcing body. The axial reinforcing bar 8 is a linear steel material and is embedded in the pile main body 2. The axial reinforcing bars 8 are arranged parallel to or substantially parallel to the axial direction along the axial direction of the pile main body 2.

Further, the axial reinforcing bars 8 are arranged at a plurality of locations around the central axis of the pile main body 2 so as to be continuous with the entire length or at least a part of the pile main body 2. That is, each axial reinforcing bar 8 is arranged so as to be continuous between the end plates 5 at both ends or to be continuous with the end plates 5 at one end. The end portion of each axial reinforcing bar 8 may be fixed to the end plate 5 by welding or the like, or may be separated from the end plate 5.

In the present embodiment, each axial reinforcing bar 8 is arranged at the center of the thickness of the pile body 2 or the center of the sum of the pile body 2 and the steel pipe 4. That is, each axial reinforcing bar 8 is arranged at an intermediate portion equidistant or substantially equidistant from the inside and the outside of the pile main body portion 2. Therefore, each axial reinforcing bar 8 is located on the central axis side of the pile main body portion 2, that is, away from the hollow portion 3 with respect to the inner peripheral surface which is the inner surface of the steel pipe portion 4. Further, each axial reinforcing bar 8 is arranged so as to be located on the same circumference or substantially on the same circumference around the central axis of the pile main body portion 2. In the illustrated example, eight axial reinforcing bars 8 are arranged. These axial reinforcing bars 8 are arranged around the central axis of the pile main body 2 at equal intervals or substantially equal intervals from each other. The amount of the axial reinforcing bar 8 is set according to the conditions of proof stress, axial force, and deformation performance required for the pile 1.

Further, an assembly bar 9, which is an assembly member, is welded to the axial reinforcing bar 8. The assembly bar 9 is formed of a linear steel material or a ring bar. The assembly bar 9 is welded to the inside of the axial reinforcing bar 8. The assembly bar 9 is embedded in the pile main body 2. The assembly bars 9 are arranged in an annular shape along a virtual circumferential surface surrounded by a plurality of axial reinforcing bars 8. In the present embodiment, the assembly bars 9 are spirally arranged along a virtual circumferential surface surrounded by a plurality of axial reinforcing bars 8. Further, in the present embodiment, the assembly bars 9 are arranged over the entire axial direction of the axial reinforcing bars 8. A plurality of axial reinforcing bars 8 are grouped together by the assembled reinforcing bars 9 to form a reinforcing bar cage 10.

Then, when manufacturing the pile 1, one end plate 5 is fixed to one end of the steel pipe portion 4, and the reinforcing bar cage 10 in which the assembled reinforcing bars 9 are welded to the plurality of axial reinforcing bars 8 in advance is attached to the other of the steel pipe portion 4. Insert from the end toward one end, fix one end of the axial rebar 8 to one end plate 5, and fix the other end of the axial rebar 8 to the other end plate 5. After fixing 5 to the other end of the steel pipe portion 4, concrete is poured inside the steel pipe portion 4 and the pile main body portion 2 is formed by centrifugal compaction or the like. The reinforcing bar 7 may be welded to the outer peripheral surface of the steel pipe portion 4 after forming the pile main body portion 2, or the reinforcing reinforcing bar 7 may be welded to the outer peripheral surface of the steel pipe portion 4 in advance and then the pile main body portion 2 is formed. You may.

As a result, the pile body portion 2 which is a concrete layer is integrally formed inside the steel pipe portion 4 and the end plate 5, the reinforcing reinforcing bar 7 is arranged on the outer peripheral surface of the steel pipe portion 4, and the axial reinforcing bar 8 and the assembled reinforcing bar 9 are formed. The pile 1 buried in the pile main body 2 is completed.

As described above, in the pile 1 of the present embodiment, the reinforcing reinforcing bars 7 are arranged so as to surround the outer peripheral surface of the cylindrical steel pipe portion 4 arranged outside the pile main body portion 2 as in the first embodiment. As a result, it is possible to obtain the same effects as those of the first embodiment, such as stable deformation performance and proof stress, and good workability.

Further, in the pile 1, in addition to the reinforcing reinforcing bar 7, axial reinforcing bars 8 are embedded over the entire length at a plurality of locations around the central axis of the pile main body 2, so that the bending performance is further improved and the toughness is improved. be able to.

Since the axial reinforcing bar 8 is arranged at the center of the thickness of the pile main body 2, the bending performance can be further improved.

Next, the third embodiment will be described with reference to FIG. The same components and operations as those of the respective embodiments are designated by the same reference numerals and the description thereof will be omitted.

In the pile 1 of the present embodiment shown in FIGS. 4A and 4B, the axial reinforcing bar 8 of the second embodiment comes into contact with the inner peripheral surface which is the inner surface of the steel pipe portion 4. Have been placed. That is, the axial reinforcing bars 8 are arranged parallel to or substantially parallel to the axial direction of the pile main body portion 2 along the inner peripheral surface of the steel pipe portion 4. The axial reinforcing bars 8 are arranged around the central axis of the pile main body portion 2 or on the inner peripheral surface of the steel pipe portion 4 at equal intervals or substantially equal intervals from each other. The axial reinforcing bar 8 may be fixed to the inner peripheral surface of the steel pipe portion 4 by welding or the like.

Then, the pile 1 is manufactured in the same manner as in the second embodiment.

As described above, in the pile 1 of the present embodiment, the reinforcing reinforcing bars 7 are arranged so as to surround the outer peripheral surface of the cylindrical steel pipe portion 4 arranged outside the pile main body portion 2 as in each embodiment. It is possible to obtain the same effects as those of the above-described embodiments, such as stable deformation performance and proof stress, and good workability.

Further, in the pile 1, in addition to the reinforcing reinforcing bar 7, axial reinforcing bars 8 are embedded over the entire length at a plurality of locations around the central axis of the pile main body 2, so that the bending performance is the same as in the second embodiment. Can be further improved to improve toughness.

Further, since the axial reinforcing bar 8 is arranged in contact with the inner peripheral surface of the steel pipe portion 4, the position of the axial reinforcing bar 8 is the sum of the central portion of the thickness of the pile main body portion 2 or the pile main body portion 2 and the steel pipe portion 4. It is located closer to the outside than the central part of the thickness of the steel pipe, and it is possible to further improve the bending performance (bending proof stress) and further reduce the sudden decrease in proof stress after buckling under high axial force. ..

In each of the above embodiments, the reinforcing bar 7 has a structure in which both ends of the linear steel material are connected to each other in an endless shape (annular shape), but both ends of the steel material are in close proximity to or in contact with each other. It may be configured not to be connected to each other.

1 Outer shell steel pipe concrete pile 2 Pile body 4 Steel pipe 7 Reinforcing bar that is a reinforcing body 8 Axial reinforcing bar that is an axial reinforcing body

Claims (5)

Pile body molded from concrete and
The tubular steel pipe part placed on the outside of this pile body and
Reinforcing body arranged around the outer surface of this steel pipe part,
An outer shell steel pipe concrete pile characterized by being equipped with. The outer shell steel pipe concrete pile according to claim 1, further comprising axial reinforcements embedded along the axial direction at a plurality of locations around the central axis of the pile main body. The outer shell steel pipe concrete pile according to claim 2, wherein the axial reinforcing body is arranged at the center of the thickness of the pile main body. The outer shell steel pipe concrete pile according to claim 2, wherein the axial reinforcing body is arranged in contact with the inner side surface of the steel pipe portion. The steel pipe part is formed in a cylindrical shape,
The outer shell steel pipe concrete pile according to any one of claims 1 to 4, wherein the reinforcing body is formed in an annular shape along the outer peripheral surface of the steel pipe portion.

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