JP6999282B2 - Pile foundation structure and its construction method - Google Patents

Description

The present invention relates to a pile foundation structure in which a joint body made of a steel pipe is provided on a pile head of a pile driven into the ground, and a method for constructing the same.

In Patent Document 1, an inner plate is installed inside the steel pipe pile at a position below a predetermined dimension from the height of the top surface of the pile head of the steel pipe pile driven into the ground, and inside the pile head of the steel pipe pile. Concrete is poured in response to the inner plate, anchor bolts are planted in the concrete, and a joint structure of a steel column and a steel pipe pile to which a base plate of a steel column is joined by the anchor bolt is disclosed. With this structure, even if the pile is driven into the ground with some misalignment, it is possible to absorb the misalignment at the joint between the pile and the column.

Further, Patent Document 2 includes a pile to which a plurality of slip prevention rings are attached to the outer periphery of the upper portion and built in the ground, a vertical position adjusting jig installed at the pile head of the pile, and a concrete filling hole. A top plate to which the superstructure is joined is provided at the upper end, a slip prevention ring is attached to the inner peripheral surface of the lower part, and the top plate is fitted to the upper part of the pile and the top plate is placed on the vertical position adjustment jig. Disclosed is a joint structure of a pile and an upper structure provided with a joining jig to be placed, a closing plate for closing the lower end of the joining jig, and concrete filled in the joining jig from the filling hole. Has been done.

Patent No. 4545470 Patent No. 4657028

By the way, when anchor bolts are used for joining piles and columns, there is a possibility that the anchor bolts will be stretched and the columns will be tilted due to the lateral load on the columns, and the inter-story deformation of the building will be large. In this regard, in the technique disclosed in Patent Document 1, since the joint portion between the column and the pile is hardened with concrete, the risk of the column inclination is small. However, in the technique disclosed in Patent Document 1, it is necessary to simultaneously install columns and perform foundation work.

On the other hand, even with the technology disclosed in Patent Document 2, it is necessary to install the pillars and perform the foundation work at the same time.

In view of the above circumstances, it is an object of the present invention to provide a pile foundation structure and a method for constructing the pile foundation structure in which foundation work and column installation can be sequentially performed.

In order to solve the above-mentioned problems, the pile foundation structure of the present invention surrounds a pile driven into the ground and a steel pile head joint surrounding the pile head of the pile protruding from the ground. It is provided with a body, a top plate provided on the upper side of the pile head joint peripheral body and having a fastening member for fastening columns projecting upward, and concrete put into the pile head joint peripheral body. It is characterized by that.

With the above configuration, after the concrete is put into the body around the pile head joint and the foundation work is completed, it is possible to carry out the work of building the columns using the fastening members in the construction method.

The fastening member may be a high-strength bolt or a medium bolt. According to this, bolt elongation as in the case of using anchor bolts is suppressed, and problems due to this elongation can be prevented.

The fastening member may fix the pillar to the top plate. Alternatively, the fastening member may fix the pillar to the top plate and the concrete.

The peripheral portion on the upper end side of the pile head joint peripheral body is located above the top plate, and the fixing portion of the pillar by the fastening member is covered with mortar or concrete using the peripheral portion on the upper end side as a formwork. You may. According to this, the fixed portion of the column is reinforced by the mortar or concrete, and the shear strength of the column base can be improved. In addition, since a separate formwork is not required, construction can be simplified.

A bottom plate is provided inside the lower part of the pile head joint peripheral body, and the bottom plate may be formed with an opening through which the pile head is passed. As a result, it is possible to improve the strength against the joint of the foundation beam to the pile head joint peripheral body. Further, the lower end of the pile head joint peripheral body may protrude below the bottom plate.

Further, the method for constructing the pile foundation structure of the present invention includes a step of driving the pile into the ground and a step of arranging a pile head joint peripheral body so as to surround the pile head of the pile protruding from the ground. It is characterized by including a step of putting concrete into the body around the pile head joint. With such a method, after the foundation work for putting the concrete is completed, the work of building the pillars can be carried out in the construction method.

According to the present invention, foundation work and pillar installation can be performed in sequence. Further, since a high-strength bolt or a medium bolt can be used as the fastening member, the bolt elongation as in the case of using an anchor bolt is suppressed, and there is an effect that a defect due to this elongation can be prevented.

It is explanatory drawing which showed the intermediate stage of the method of constructing the pile foundation structure which concerns on embodiment of this invention. It is explanatory drawing which showed the cross section of the pile foundation structure which concerns on embodiment of FIG. It is a perspective explanatory view of the pile foundation structure which concerns on embodiment of FIG. It is explanatory drawing which showed the pile foundation structure which concerns on other embodiment of this invention. It is explanatory drawing which showed the pile foundation structure which concerns on other embodiment of this invention. It is explanatory drawing which showed the pile foundation structure which concerns on other embodiment of this invention.

Hereinafter, the pile foundation structure according to the embodiment of the present invention will be described with reference to the accompanying drawings. FIG. 1 shows an intermediate stage of a method for constructing a pile foundation structure according to this embodiment, and FIGS. 2 and 3 show a pile foundation structure according to this embodiment.

In the pile foundation structure according to this embodiment, the pile 1 made of a circular steel pipe is driven into the ground of the root cutting portion 100. The upper end of the pile 1 protrudes from the bottom surface of the root cutting portion 100 at a height equal to or larger than the outer diameter of the pile 1. At the upper end of the pile 1, for example, a disk-shaped pile head 11 having a diameter larger than the outer diameter of the pile 1 is provided. Further, the pile head 11 is formed with an opening 11a smaller than the inner diameter of the pile 1. Then, the concrete 12 is filled on the upper side of the pile 1 at a depth of about 1 m. A disk-shaped pile head 11 may be formed at a position below the upper end of the pile 1, and not limited to the disk-shaped pile head 11, a reinforcing bar may be formed on the upper end side of the pile 1. Etc. can be provided to form a pile head.

A pile head joint peripheral body 2 made of a circular steel pipe is arranged so as to surround the circumference of the pile head 11. A bottom plate 21 is horizontally provided inside the lower portion of the pile head joint peripheral body 2, and an opening 21a through which the pile head 11 is passed is formed in the bottom plate 21. The diameter of the opening 21a is set so as to be able to absorb the driving error of the pile 1 (for example, about 100 mm), and is larger than the pile head 11. Further, the bottom plate 21 is provided at a position above the lower end of the pile head joint peripheral body 2, and the lower end of the pile head joint peripheral body 2 protrudes below the bottom plate 21. It has become. Further, the bottom plate 21 is provided so as to project to the outside of the pile head joint peripheral body 2 in the shape of a through diaphragm.

A top plate 22 is provided on the upper surface of the pile head joint peripheral body 2. The top plate 22 is formed with, for example, a circular opening 22a in which the concrete 3 can be put into the pile head joint peripheral body 2. Further, on the top plate 22, a bolt (high-strength bolt or medium bolt) 22b, which is a fastening member, is located outside the outer periphery of the opening 22a, and its head is positioned in the pile head joint peripheral body 2. It is provided so that the screw portion is projected upward. The bolt 22b is temporarily fixed by a temporary fixing nut 22c on the upper surface side of the top plate 22 while being passed through an insertion hole formed in the top plate 22, for example. The temporary fixing nut 22c may be removed after the concrete 3 has hardened. Further, the setting of the bolt 22b can be performed by the operator by putting his / her hand through the opening 22a at the stage where the concrete 3 has not been put in. Further, the edge surface of the top plate 22 protrudes to the outside of the pile head joint peripheral body 2, and this protruding portion serves as a joint portion of the underground beam 4.

An underground beam 4 is attached to the side surface of the pile head joint peripheral body 2. Of course, the beam is not limited to the underground beam 4, and can be a foundation beam that is not completely buried in the ground. The underground beam 4 is made of, for example, H-shaped steel, the lower flange is welded to the edge surface of the protruding portion of the bottom plate 21, the upper flange is welded to the edge surface of the top plate 22, and the web is the pile head. It is welded to the outer surface of the joint peripheral body 2. Of course, the underground beam 4 is not limited to being joined to the pile head joint peripheral body 2 by such welding.

When the concrete 3 is filled from the opening 22a of the top plate 22, the concrete 3 is present around the pile head 11 in the pile head joint peripheral body 2. Further, the concrete 3 is also present on the lower side of the bottom plate 21 due to the concrete outflow downward from the opening 21a. When the concrete 3 is hardened, the temporary fixing nut 22c can be removed and the pillar 5 can be fixed to the top plate 22. An insertion hole through which the bolt 22b is inserted is formed in the base plate 5a of the pillar 5, and the bolt 22b is inserted through the insertion hole to tighten the nut 55. The concrete 3 is not limited to being filled from the opening 22a of the top plate 22, but the concrete 3 may be filled from the lower side of the pile head joint peripheral body 2, and the top plate 22 is filled with air. The loophole 22d may be formed. Further, instead of fully filling the concrete 3 in the pile head joint peripheral body 2, the concrete 3 is poured up to, for example, about 50 mm below the lower surface of the top plate 22, and the concrete 3 is filled with non-shrink mortar. You may try to do it.

Here, the pile head joint peripheral body 2 is lifted by, for example, a crane and lowered so that the pile head 11 enters the pile head joint peripheral body 2. At this time, even if an error occurs in the driving position of the pile 1, the diameter of the opening 21a formed in the bottom plate 21 is set to a size capable of absorbing the driving error of the pile 1. The pile head joint peripheral body 2 can be shifted and installed at a specified position. In this installation, for example, the installation height of the pile head joint peripheral body 2 can be adjusted by interposing members having a substantially L-shaped cross section at four locations at the lower ends of the pile head joint peripheral body 2. Further, in this installation, a gap is formed between the lower side of the pile head joint peripheral body 2 and the lower side of the bottom plate 21 and the bottom surface of the root cutting portion 100. When the concrete 3 filled in the pile head joint peripheral body 2 leaks from the gap, a damming plate (frame) 6 is arranged on the outer peripheral side of the lower portion of the pile head joint peripheral body 2. The concrete 3 that is about to leak from the gap may be blocked.

Further, as described above, one form of the method of constructing the pile foundation structure is a step of driving the pile 1 into the ground and a pile so as to surround the pile head 11 of the pile 1 protruding from the ground. A step of arranging the head joint peripheral body 2, a step of providing a fastening member (bolt 22b) for column joining on the top plate 22 provided on the upper side of the pile head joint peripheral body 2, and a step of forming on the top plate 22. Includes the step of filling concrete from the openings that have been made. The filling of the concrete 3 can be performed when the soil concrete is struck.

In the case of the pile foundation structure, the steel pile head joint peripheral body 2 surrounding the pile head 11 and the concrete 3 filled in the pile head joint peripheral body 2 form a so-called column base portion. A CFT (Concrete Filled Steel Tube) structure is obtained. Further, after the foundation work for filling the concrete 3 is completed, the work of constructing the pillar 5 by using the fastening member (bolt 22b) can be performed in the construction method. That is, since it is not necessary to be restricted by the simultaneous progress of the installation of the pillar 5 and the foundation work, it is possible to realize a desirable construction procedure particularly in the construction of a house.

Further, if the bolt 22b is a high-strength bolt or a medium bolt, it is not fixed by concrete like an anchor bolt, so that elongation when an anchor bolt is used is suppressed, and problems due to this can be prevented, and the bolt 22b By using the above, the base plate 5a of the pillar 5 can be rigidly joined to the top plate 22.

Further, the structure is such that the lower end of the pile head joint peripheral body 2 projects below the bottom plate 21, but the structure is not limited to this, and the lower end of the pile head joint peripheral body 2 and the bottom plate 21 may be flush with each other. It's a good one.

FIG. 4 shows the pile foundation structure of another embodiment. In this pile foundation structure, the bolt 22b is temporarily fixed to the top plate 22 by using the cap 56. The cap 56 is fixed to the bottom surface of the top plate 22 by welding, for example. When the cap 56 is used, it is not necessary to fully fill the concrete 3 to just below the top plate 22, and the nut 22c for temporary fixing can be omitted. In addition, in FIG. 1 and the configuration of FIG. 4, the top plate 22 is made thicker than the structure of FIG. 5 described later. Further, by welding and fixing the bolt 22b to the top plate 22, or by cutting and screwing the tap, the nut 22c for temporary fixing can be omitted, and the full filling can be avoided.

FIG. 5 shows the pile foundation structure of another embodiment. In this pile foundation structure, a bolt 22e is provided in place of the bolt 22b. The bolt 22e has a fixing plate 22d on the head side. Since the fixing plate 22d is fixed to the hardened concrete 3, the pillar 5 is fixed to the concrete 3 and the top plate 22. Of FIGS. 1, 4, and 5, the top plate 22 in FIG. 4 is made thickest, then the top plate 22 in FIG. 1 is made thicker, and the top plate 22 in FIG. 5 can be made the thinnest. Before the concrete 3 is filled, the bolt 22e is temporarily fixed to the top plate 22 by the temporary fixing nuts 22c provided on the upper surface and the lower surface of the top plate 22. After the concrete 3 is hardened, the upper nut 22c can be removed, the insertion hole of the base plate 5a can be passed through the bolt 22e, and the pillar 5 can be fixed with the nut 55.

FIG. 6 shows the pile foundation structure of another embodiment. In this pile foundation structure, the upper end side peripheral portion 2b of the pile head joint peripheral body 2 is located above the top plate 22. Then, the fixing portion of the pillar 5 by the fastening member (bolt 22b) is covered with mortar 31 (or concrete) using the upper end side peripheral portion 2b as a formwork. According to this, the fixed portion of the column 5 is reinforced by the mortar 31, and the shear strength of the column base can be improved. In addition, since a separate formwork is not required, construction can be simplified.

Further, in the above example, the pile head joint peripheral body 2 is a circular steel pipe, but it can also be a square steel pipe.

Although the embodiment of the present invention has been described above with reference to the drawings, the present invention is not limited to that of the illustrated embodiment. Various modifications and modifications can be made to the illustrated embodiment within the same range as the present invention or within the same range.

1: Pile 2: Pile head joint peripheral body 2b: Upper end side peripheral part 3: Concrete 4: Underground beam 5: Pillar 5a: Base plate 6: Dam stop plate 11: Pile head 11A: Pile head 11a: Bolt-shaped member 11b: Nut 11c: Double-cut bolt-shaped member 12: Concrete 13: Plate 14: Nut 21: Bottom plate 21a: Opening 22: Top plate 22a: Opening 22b: Bolt 22c: Temporary fixing nut 31: Mortal 41: Bolt nut 100: Root cutting point

Claims (8)

It is provided on the upper side of the pile driven into the ground, the steel pile head joint peripheral body surrounding the pile head of the pile protruding from the ground, and the pile head joint peripheral body. , The top plate in which the fastening member for fastening the pillars is projected upward, and the concrete put into the body around the pile head joint are provided.
The concrete is also filled in the gap between the lower end side of the pile head joint peripheral body and the outer circumference of the pile below the pile head in the pile .
A pile foundation structure characterized in that a bottom plate is provided inside the lower part of the pile head joint peripheral body, and an opening through which the pile head is passed is formed in the bottom plate . The pile foundation structure according to claim 1, wherein the fastening member is a high-strength bolt or a medium bolt. The pile foundation structure according to claim 1 or 2, wherein the fastening member fixes the pillar to the top plate. The pile foundation structure according to claim 1 or 2, wherein the fastening member fixes the pillar to the top plate and the concrete. It is provided on the upper side of the pile driven into the ground, the steel pile head joint peripheral body surrounding the pile head of the pile protruding from the ground, and the pile head joint peripheral body. , The top plate in which the fastening member for fastening the pillars is projected upward, and the concrete put into the pile head joint peripheral body are provided, and the upper end side peripheral portion of the pile head joint peripheral body is the top. A pile foundation structure that is located above the plate and whose upper end side peripheral portion is used as a mold and the fixing points of the pillars by the fastening members are covered with mortar or concrete. The pile foundation structure according to claim 5 is characterized in that a bottom plate is provided inside the lower part of the pile head joint peripheral body, and the bottom plate is formed with an opening through which the pile head is passed. Pile foundation structure. The pile foundation structure according to any one of claims 1 to 4 or 6, wherein the lower end of the pile head joint peripheral body projects downward from the bottom plate. .. The process of driving the pile into the ground, the process of arranging the pile head joint surrounding body so as to surround the pile head of the pile coming out of the ground, and the step of putting concrete into the pile head joint surrounding body, the said The step of filling the gap between the lower end side of the pile head joint peripheral body and the outer circumference of the pile below the pile head in the pile is also included.
On the upper side of the pile head joint peripheral body, a top plate is provided in which a fastening member for fastening the pillar is projected on the upper side. A method of constructing a pile foundation structure, which is characterized by fastening with concrete.

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