JP2010248812A - Double tube-type pile head structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a double tube-type pile head structure which has an outer pipe inserted into a head of a steel pipe pile, increases horizontal strength by filling a substance with a high Young's modulus between the steel pipe pile and the outer pipe and integrating the head of the steel pipe pile and the outer pipe to each other, and can withstand even a compressive force and a pulling force. <P>SOLUTION: A grout material 13 is filled between the steel pipe pile 11 and the outer pipe 12 by inserting the outer pipe 12 into the head of the steel pipe pile 11; and an anchoring plate 15 is attached to an upper end of the outer pipe 12. Upper portions of the steel pipe pile 11 and the outer pipe 12 which are filled with the grout material 13, and the anchoring plate 15 are embedded in the concrete of a footing 14. Since the steel pipe pile 11 and the outer pipe 12 are integrally and firmly connected to each other by means of the grout material 13, horizontal strength is greatly increased, and the compressive force and a pulling force are transferred to the steel pipe pile 11 from the anchoring plate 15. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a double-pipe pile head structure in a foundation pile.

Conventionally, in order to increase the horizontal proof stress during an earthquake, an outer pipe (outer pipe) larger in diameter than the steel pipe pile is inserted into the head of the steel pipe pile, and a double pipe filled with a filler between the steel pipe pile and the outer pipe The type pile head structure is proposed (refer to patent documents 1).
FIG. 2 shows a cross section in the tube axis direction of a conventional double-pipe pile head structure.
In the double-pipe pile head structure, an outer pipe 32 is inserted into the head of the steel pipe pile 31, and a filler 33 is filled between the steel pipe pile 31 and the outer pipe 32. A material having a Young's modulus of 10 to 10000 N / mm ² (for example, a soil cement having a Young's modulus of 70 N / mm ² ) having a Young's modulus lower than that of the concrete of the footing 35 is used as the filler 33. Incidentally, the Young's modulus of the concrete of the footing 35 is about 25000 N / mm ² . Reinforcing bars 341 and 342 are attached to the head of the steel pipe pile 31 and the head of the outer pipe 32. A part of the head of the outer pipe 32, all of the reinforcing bars 341, and a part of the reinforcing bars 342 are buried in the concrete of the footing 35, and the head of the steel pipe pile 31 is filled with the concrete of the footing 35 inside. .

JP 2009-46879 A

The conventional double-pipe pile head structure uses a filler 33 having a Young's modulus of about 10 to 10000 N / mm ^{2 in} order to increase the resistance to horizontal forces caused by earthquakes. Although it is configured to be transmitted to the steel pipe pile 31 via the material 33, the outer pipe 32 and the steel pipe pile 31 have a low degree of coupling and move separately with respect to the external force because the Young's modulus of the filler 33 is small. Does not move. Therefore, the conventional double-pipe pile head structure has a low horizontal proof stress, and it is difficult for the compressive force and pull-out force due to the upper structure (not shown) to be transmitted to the steel pipe pile 31, so that the footing may be damaged.
The present invention has been made in view of the above-described problems of conventional double-pipe pile head structures, and it is an object of the present invention to provide a double-pipe pile head structure that has a large horizontal proof strength and is resistant to compressive force and pull-out force.

In order to achieve the object of the present invention, the double pipe type pile head structure according to claim 1 is a double pipe in which a filler is filled between the head of the steel pipe pile into which the outer pipe is inserted and the outer pipe. In the pile head structure, a fixing plate that has a hook-like part and closes the opening of the outer pipe is attached to the upper end of the outer pipe, the grout material is filled between the head of the steel pipe pile and the outer pipe, and the grout material is filled The head of the steel pipe pile, the upper part of the outer pipe and the fixing plate are buried in the concrete of the footing.
The double-pipe pile head structure according to claim 2 is characterized in that, in the double-pipe pile head structure according to claim 1, the lower end portion of the outer pipe is bent toward the steel pipe pile side.
The double-pipe pile head structure according to claim 3 is the double-pipe pile head structure according to claim 1 or 2, wherein the grout material is between the fixing plate and the upper end of the steel pipe pile. The space is also filled.
The double-pipe pile head structure according to claim 4 is the double-pipe pile head structure according to claim 3, wherein the grout material is also filled inside the head of the steel pipe pile. Features.

In the present invention, the grout material is filled between the head of the steel pipe pile and the outer pipe, and the head and the outer pipe of the steel pipe pile are firmly and integrally joined. When the force in the horizontal direction is applied, they move as a unit, and the two do not move separately as in the conventional case, so that the strength of the pile head is greatly improved. Moreover, by integrating the steel pipe pile head and outer pipe with grout material, the steel pipe pile has a structure in which the outer diameter of the head is substantially increased (or the head is thickened) and the wall thickness is increased. Since the structure is the same, the strength of the head is greatly improved.
In the present invention, since the head of the steel pipe pile filled with the grout material, the upper part of the outer pipe and the fixing plate are buried in the concrete of the footing, the head strength of the steel pipe pile and the outer pipe have a bonding strength with the footing. However, the bond strength is further increased by integrating the steel pipe pile head and the outer pipe with a grout material.
Since the fixing plate 15 is attached to the upper end of the outer tube 12, the compressive force of the upper structure is transmitted to the upper surface of a wide area of the fixing plate 15, and the pulling force is around the fixing plate. Therefore, the footing is not damaged by the compressive force or the pulling force. And the intensity | strength with respect to external forces, such as a horizontal force, a compressive force, and a drawing force, improves further by integrally couple | bonding the head of a steel pipe pile, an outer tube, and a fixing board with a grant material.

FIG. 1 shows a configuration of a double-pipe pile head structure according to an embodiment of the present invention. FIG. 2 shows a configuration of a conventional double-pipe pile head structure.

The inventor of the present application conducted various experiments on the filler having a double pipe pile head structure. As a result, when the filler is bonded using a material having a higher Young's modulus than concrete, the steel pipe pile and the outer pipe are integrally bonded. Therefore, it was found that the strength of the double-pipe pile head structure was greatly improved. It has also been found that a grout material (for example, mortar) is suitable as a material having a higher Young's modulus than concrete. Incidentally, the Young's modulus of concrete is about 25000 N / mm ² . As the grout material, a synthetic resin system can be used in addition to the mortar system.
In the double pipe type pile head structure of the present invention, a grout material is filled between the steel pipe pile and the outer pipe so that they are integrally and firmly joined together, and a fixing plate is attached to the upper end of the outer pipe. By connecting the steel pipe pile and the outer pipe integrally with the grout material, when a horizontal force is applied to the steel pipe pile and the outer pipe, both move together and do not move separately as in the past. The strength of the pile head is greatly improved. The steel pipe pile has a structure in which the outer diameter of the head is substantially increased (or the head is thickened) and is made thick by integrating the head and outer pipe of the steel pipe pile with a grout material. Since the structure is the same, the strength is greatly improved.

  In addition, the compressive force and pulling force by the superstructure are first transmitted to a large area fixing plate attached to the upper end of the outer pipe, but the outer pipe and the steel pipe pile are joined together by the grout material. It is also transmitted to steel pipe piles. That is, since the fixing plate, the outer tube, and the steel tube pile having a large area are integrally received by the compression force and the pulling force, those forces are not concentrated on a specific portion of the footing. Therefore, the footing is not damaged by the compression force and the pulling force.

FIG. 1 shows a configuration of a double-pipe pile head structure according to an embodiment.
An outer pipe 12 having an inner diameter larger than the outer diameter of the steel pipe pile 11 is inserted into the head of the steel pipe pile 11, and a grout material 13 is injected and filled between the two. A fixing plate 15 that closes the opening of the outer tube 12 by a weld 16 is attached to the upper end of the outer tube 12, and the lower end 121 of the outer tube 12 is bent toward the steel tube pile 11 side so as to adhere to the outer periphery of the steel tube pile 11. is there. The fixing plate 15 protrudes in a bowl shape larger than the outer diameter of the outer tube 12 and has a hole 151 for injecting the grout material 13. A grout material fall prevention member 17 is attached to the upper end of the steel pipe pile 11 to prevent the grout material 13 from flowing into the steel pipe pile 11. Note that the grout material fall prevention member 17 may not be provided.

  Since the lower end portion 121 of the outer pipe 12 is bent toward the steel pipe pile 11 and is in close contact with the outer periphery of the steel pipe pile 11, the grout material 13 does not leak when the grout material 13 is injected. Even if there is a gap through which the grout material 13 leaks, the lower end portion 121 of the outer tube 12 is driven into the ground, so that the grout material 13 is prevented from flowing out by the surrounding soil. Moreover, since the space | interval of the steel pipe pile 11 and the outer pipe 12 is decided by the magnitude | size of the bending part by bending the lower end part 121 of the outer pipe 12 to the steel pipe pile 11 side, when driving the outer pipe 12, The spacing between the outer pipes 12 can be kept uniform, so that the operation of driving the outer pipes 12 becomes easy, and the thickness of the grout material 13 between the steel pipe piles 11 and the outer pipes 12 can be made uniform.

  Since the head of the steel pipe pile 11 and the outer pipe 12 are integrally and firmly joined by the grout material 13, the horizontal strength of the pile head is greatly improved as described above, and the outer diameter of the pile head is substantially increased. It produces the same effect as making it larger. Moreover, since the head part of the steel pipe pile 11 integrated with the grout material 13, the upper part of the outer pipe 12, and the fixing plate 15 are buried in the concrete of the footing 14, the bonding strength with the footing 14 is improved, and the upper structure. The compression force (not shown) is transmitted to the upper surface of a wide area of the fixing plate 15, and the pulling force can be dealt with by the support pressure of the lower surface 152 around the fixing plate (saddle-shaped portion). It will not be damaged by force or pulling force.

  In FIG. 1, the upper end of the steel pipe pile 11 is made lower than the upper end of the outer pipe 12, the space 18 is set to a predetermined height, and the grout material 13 may be injected so as to fill the space 18, Furthermore, the grout material fall prevention member 17 may be moved from the upper end of the steel pipe pile 11 to a position at a predetermined depth 18 to inject the grout material 13 also into the steel pipe pile 11. Further, a bolt may be attached to the lower surface of the fixing plate 15 so that the vertical position of the fall prevention member 17 can be adjusted along the bolt. When the grout material is also injected into the steel pipe pile 11, the fixing plate 15, the outer pipe 12, and the head of the steel pipe pile 11 are integrally coupled by the grout material 13, so that the strength against external force is further improved. Also, the outer tube 12 and the fixing plate 15 may be provided with a bolt attached to the head of the outer tube 12, an insertion hole for the bolt is formed in the fixing plate 15, and the outer tube 12 and the fixing plate 15 are coupled with the bolt and nut. Good.

  The construction of the double pipe type pile head structure is as follows. First, the steel pipe pile 11 is driven into the ground, then the outer pipe 12 is inserted into the head of the steel pipe pile 11 and driven to prevent the grout material from falling on the upper end of the steel pipe pile 11. The member 17 is attached. Next, the fixing plate 15 is attached to the upper end of the outer tube 12. Next, the grout material 13 is injected between the steel pipe pile 11 and the outer pipe 12 from the hole 151 of the fixing plate 15 and filled. Next, the footing 14 is constructed by placing concrete so that the fixing plate 15, the head of the steel pipe pile 11 and the upper part of the outer pipe 12 are buried.

11 Steel pipe pile 12 Outer pipe 121 Lower end of outer pipe 13 Grout material (filler)
14 Footing 15 Fixing Plate 151 Grout Material Injection Hole 152 Lower Surface 16 of Fixing Plate Gutter-like Part Welding Portion 17 Grout Material Fall Prevention Member

Claims (4)

  In a double-pipe pile head structure in which a filler is filled between the head of the steel pipe pile into which the outer pipe is inserted and the outer pipe, the fixing plate that has a hook-like part and closes the opening of the outer pipe is attached to the upper end of the outer pipe. The steel pipe pile head and outer pipe are filled with grout material, and the steel pipe pile head filled with grout material, the upper part of the outer pipe and the fixing plate are buried in the footing concrete. Double pipe type pile head structure.   The double pipe type pile head structure of Claim 1 WHEREIN: The lower end part of an outer pipe is bent to the steel pipe pile side, The double pipe type pile head structure characterized by the above-mentioned.   The double pipe pile head structure according to claim 1 or 2, wherein the grout material is also filled in a space between the fixing plate and an upper end of the steel pipe pile. Pile head structure.   The double pipe type pile head structure according to claim 3, wherein the grout material is also filled in a head portion of the steel pipe pile.

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