JP6999281B2 - 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, there is a drawback that the outer steel pipe becomes large because the misalignment of the pile driving is absorbed at the joint between the pile and the column. In addition, it is necessary to install pillars and perform foundation work at the same time.

On the other hand, even in the technique disclosed in Patent Document 2, it is necessary to increase the size of the joining jig in order to absorb the misalignment of the pile driving at the joint portion between the pile and the column. In addition, it is necessary to install pillars and perform foundation work at the same time.

In view of the above circumstances, the present invention can prevent the pile head joint peripheral body from becoming large in order to absorb the misalignment at the joint between the pile and the column, and the foundation work and the column installation can be sequentially performed. The purpose is to provide a foundation structure and a method for constructing the foundation structure.

The pile foundation structure of the present invention has a pile driven into the ground, a pile head that is thinner than the pile and is erected on the upper part of the pile, and a pile head, in order to solve the above problems. A steel pile head joint peripheral body that surrounds the circumference of the pile head joint, a top plate provided on the upper side of the pile head joint peripheral body on which columns are arranged, and concrete put into the pile head joint peripheral body. , Is characterized by the provision of.

With the above configuration, the pile head joint peripheral body may be displaced to a predetermined position with respect to the pile head thinner than the pile in order to prevent the misalignment of the driving of the pile. The void region set on the pile head joint peripheral body side for avoiding contact with the portion can be made narrower than the void region set on the pile itself. As a result, it is possible to eliminate the misalignment while reducing the width of the pile head joint peripheral body to make it slimmer. Further, after the concrete is filled in the body around the pile head joint and the foundation work is completed, the work of building the pillars can be carried out in the construction method.

The pillar may be fixed by high-strength bolts or medium bolts. According to this, bolt elongation as in the case of using anchor bolts is suppressed, and problems due to this elongation can be prevented. Further, by using the high-strength bolt or the medium bolt, the base plate of the pillar can be rigidly joined to the portion of the pile head joint peripheral body to which the pillar is attached.

The pile head may be erected by concrete filled on the upper side of the pile. Alternatively, the pile head may be erected by being fixed to a plate portion attached to the upper side of the pile.

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. The diameter of the opening may be smaller than the diameter of the pile. Further, the lower end of the pile head joint peripheral body may protrude below the bottom plate.

Further, the method of constructing the pile foundation structure of the present invention includes a step of driving the pile into the ground, a step of erection of a pile head thinner than the pile on the upper side of the pile, and a step of surrounding the pile head. It is characterized by including a step of arranging a pile head joint peripheral body in the pile head joint and a step of putting concrete into the pile head joint peripheral body. With such a method, after the foundation work for filling the concrete is completed, the work of building the pillars can be carried out in the construction method.

According to the present invention, it is possible to suppress the increase in the size of the pile head joint peripheral body in order to absorb the misalignment at the joint between the pile and the column, and it is possible to carry out the foundation work and the column installation in sequence.

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

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, for example, a pile 1 made of a circular steel pipe is driven into the ground of a root cutting portion 100. The upper end of the pile 1 may or may not protrude slightly from the bottom surface of the root cutting portion 100. On the upper side of the pile 1, a pile head 11 having a diameter smaller than the inner diameter of the pile 1 is provided. In the pile head 11, for example, a metal bolt-shaped member 11a is arranged so that the head thereof faces downward, and the tip screw portion of the bolt-shaped member 11a is formed from the diameter of the bolt-shaped member 11a. Also has a structure provided with a large nut 11b. The upper side of the pile 1 is filled with concrete 12 at a depth of about 1 m, and the pile head 11 is erected and supported by the hardened concrete 12. In addition, another bolt-shaped structure may be used as the bolt-shaped structure of the pile head 11, and the pile head 11 is not limited to the bolt-shaped structure, for example, a plurality of pile heads 11. It is also possible to have a structure in which the reinforcing bars of the above are arranged in an annular shape having a diameter smaller than the inner diameter of the pile in the pile.

A pile head joint peripheral body 2 made of a square 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 while being larger than the outer diameter of the pile 1, for example. It has been made smaller. Further, a plurality of drain holes 21b are formed at the edge of the bottom plate 21. 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.

A top plate 22 is provided on the upper surface side 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, has a bolt (high-strength bolt or medium bolt) 22b, which is a fastening member, at a portion outside the outer periphery of the opening 22a, and its head is placed in the pile head joint peripheral body 2. It is positioned so that the screw portion protrudes 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, 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, and has an end plate 4a on its end face. A plurality of insertion holes are formed in the end plate 4a in the horizontal direction. Further, on the side surface of the pile head joint peripheral body 2, a plurality of insertion holes are formed in the horizontal direction in an arrangement corresponding to the arrangement of the insertion holes of the end plate 4a. The underground beam 4 is fixed to the side surface of the pile head joint peripheral body 2 by bolts and nuts 41 provided through the insertion hole. The fastening work with the bolts and nuts 41 can be performed by the operator by putting his / her hand through the opening 22a when the concrete 3 has not been put in.

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 from the opening 22a of the top plate 22 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 standing a pile head 11 thinner than the pile 1 on the upper side of the pile 1. A step of setting, a step of arranging the pile head joint peripheral body 2 so as to surround the pile head 11 and a fastening member for column joining to the top plate 22 provided on the upper side of the pile head joint peripheral body 2. It has a step of providing (bolt 22b), a step of attaching an underground beam to the pile head joint peripheral body 2, and a step of filling concrete 3 from the opening 22a of the top plate 22. Regarding the step of attaching the underground beam, in addition to the method of fastening the underground beam 4 made of the H-shaped steel, for example, a member to be a reinforcing bar when the underground beam is made of reinforced concrete is joined to the pile head. There is also a method of attaching to the peripheral body 2. Further, 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. Then, the semi-rigid joint structure can be obtained by the presence of the pile head 11 thinner than the pile 1 in the pile head joint peripheral body 2.

Further, with respect to the misalignment of the driving of the pile 1, the pile head joint peripheral body 2 may be displaced to a predetermined position with respect to the pile head 11 which is thinner than the pile 1. Therefore, the pile head may be displaced. The gap region set on the pile head joint peripheral body 2 side for avoiding contact with 11 can be made narrower than the gap region set on the pile itself. As a result, the width of the pile head joint peripheral body 2 can be reduced and slimmed down while eliminating the misalignment. In addition to the misalignment of the center, the position of the pile head 11 can be displaced with respect to the misalignment of the pile 1. Further, when the pile itself is inserted into the joint peripheral body, the height of the joint peripheral body is increased from the viewpoint of joining with the beam because the pile itself is inserted to a depth similar to the pile diameter. By inserting the pile head 11 into the pile head joint peripheral body 2, the height of the pile head joint peripheral body 2 can be lowered.

Further, after the foundation work for filling the concrete 3 is completed, the work of building the pillar 5 can be carried out 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. As the fastening member, a fixing plate in which the head of the bolt is embedded and fixed in the concrete 3 can also be used.

When the bottom plate 21 is provided inside the lower part of the pile head joint peripheral body 2, it is possible to improve the strength against the joint of the underground beam 4 to the pile head joint peripheral body 2.

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.

4 and 5 show the pile foundation structure of another embodiment. In this pile foundation structure, the pile head 11A is provided with, for example, a double-cutting bolt member 11c, and has a structure in which a nut 11b is provided on a screw portion at an upper end of the double-cutting bolt member 11c. The pile head 11A is erected on the upper part of the pile 1 by being fixed to the plate portion 13 attached to the upper surface of the pile 1. In this example, the lower end side of the pile head 11A is inserted into the insertion hole formed in the plate portion 13 in the vertical direction, and the upper side and the lower side of the plate portion 13 are screwed into the double-cut bolt member 11c, respectively. The two nuts 14 are tightened and the pile head 11A is fixed to the plate portion 13. The plate portion 13 may be fixed to the upper end of the pile 1 by welding at the site, for example. The lower nut 14 may be welded and fixed to the plate portion 13. It is desirable that the plate thickness of the plate portion 13 is thick. Further, the concrete 12 may be filled in the upper part of the pile 1.

Further, in the above example, the pile head joint peripheral body 2 is a square steel pipe, but it can also be a circular 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 3: Concrete 4: Underground beam 4a: End plate 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 21b: Drain hole 22: Top plate 22a: Opening 22b: Bolt 22c: Temporary fixing nut 41: Bolt / nut 100: Root cutting point

Claims (8)

A pile made of steel pipes driven into the ground, a pile head that is thinner than the above pile and is erected with the lower side positioned in the pipe at the top of the pile, and is not directly joined to the pillar, and the above pile head. A steel pile head joint peripheral body surrounding the periphery, a top plate provided on the upper side of the pile head joint peripheral body on which the pillars are arranged, and concrete put into the pile head joint peripheral body. A pile foundation structure characterized by being equipped with. The pile foundation structure according to claim 1, wherein the pillar is fixed by a high-strength bolt or a medium bolt. The pile foundation structure according to claim 1 or 2, wherein the pile head is erected by concrete filled on the upper side of the pile. In the pile foundation structure according to claim 1 or 2, the pile foundation structure is characterized in that the pile head is erected by being fixed to a plate portion attached to the upper side of the pile. .. A pile made of steel pipes driven into the ground, a pile head that is thinner than the pile and is erected with the lower side located in the pipe at the top of the pile, and a steel that surrounds the circumference of the pile head. Pile foundation structure including a pile head joint peripheral body, a top plate provided on the upper side of the pile head joint peripheral body on which columns are arranged, and concrete put into the pile head joint peripheral body. The pile foundation structure is 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 5, wherein the diameter of the opening is smaller than the diameter of the pile. The pile foundation structure according to claim 5 or 6, wherein the lower end of the pile head joint peripheral body projects downward from the bottom plate. The process of driving a pile made of steel pipes into the ground, the process of erection of a pile head that is thinner than the pile and is not directly joined to the pillar by locating the lower side in the pipe at the top of the pile, and the pile head. A method for constructing a pile foundation structure, which comprises a step of arranging a pile head joint peripheral body so as to surround the portion and a step of putting concrete into the pile head joint peripheral body.

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