JP6916643B2 - Pile foundation structure and its construction method - Google Patents

Description

The present invention relates to a pile foundation structure in which a joint 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. A joint structure of a steel column and a steel pipe pile is disclosed in which concrete is cast in response to the inner plate, anchor bolts are planted in the concrete, and the base plate of the steel column is joined by the anchor bolts. 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 on the ground, a vertical position adjusting jig installed on 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 stopper 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. Disclosure of a joining structure of a pile and an upper structure including a joining jig to be placed, a closing plate for closing the lower end of the joining jig, and concrete filled into the joining jig from the filling hole. Has been done.

Patent No. 4545470 Patent No. 4657028

By the way, when an anchor bolt is used for joining a pile and a column, the anchor bolt may be extended and the column may be tilted due to a lateral load on the column to increase the inter-story deformation of the building. 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, an object of the present invention is to provide a pile foundation structure capable of suppressing an increase in the surrounding body of a pile head joint in order to absorb misalignment at a joint portion between a pile and a column, and a method for constructing the pile foundation structure. do.

In order to solve the above problems, the pile foundation structure of the present invention includes 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 the pile head. Inside the steel pile head joint surrounding body surrounding the pile head joint, the pillar base portion in which the upper side of the pile head is inserted while entering the pile head joint surrounding body, and inside the pile head joint surrounding body and the pillar base portion. It is characterized by being provided with charged concrete.

With the above configuration, the column base and the pile head joint peripheral body may be shifted to the predetermined positions with respect to the pile head thinner than the pile in order to prevent the misalignment of the driving of the pile. Therefore, the gap area set on the column base side for avoiding contact with the pile head can be made narrower than the gap area set for 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, since the upper side of the pile head is inserted into the column base portion, the joint strength between the pile and the column base portion can be improved. Further, the height of the pile head joint peripheral body can be lowered as compared with the structure in which the upper side of the pile head is not positioned in the column base portion.

The column base may be separate from the column body and may be connected to the column body. According to this, in the foundation work, the pillar base is placed instead of the entire pillar, and the concrete is put into the pillar base and the body around the pile head joint to finish the foundation work, and then in the construction method. You can work on building the pillar body.

The pile head may be erected by concrete thrown into the upper side of the pile. Alternatively, the pile head may be fixed to a plate portion attached to the upper surface of the pile.

A bottom plate having an opening may be provided inside the lower part of the pile head joint peripheral body. With the bottom plate, it is possible to improve the strength against joining 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.

A support portion for supporting the column base portion may be provided in the body around the pile head joint. According to this, in the construction of the pile foundation structure, the concrete can be thrown in while the column base portion is supported. Further, the support portion may be provided with means for regulating the horizontal displacement of the column base portion. According to this, it is possible to prevent the column base portion from being displaced in the horizontal direction due to the injection of the concrete.

Further, the method for 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. The step of arranging the pile head joint peripheral body as described above, the step of locating the lower side of the column base portion inside the pile head joint peripheral body, and the step of inserting the upper side of the pile head from the opening on the lower surface side, and concrete. Is included in the body around the pile head joint and in the column base portion.

According to the present invention, there is an effect that the pile head joint peripheral body can be suppressed from becoming large in order to absorb the misalignment at the joint portion between the pile and the column.

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 step 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 the method for constructing the pile foundation structure according to this embodiment, and FIGS. 2 and 3 show the 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. A pile head 11 having a diameter smaller than the inner diameter of the pile 1 is provided on the upper side of the pile 1. 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 to a depth of about 1 m, and the pile head 11 is erected and supported by the hardened concrete 12. In addition, another bolt-like structure may be used as the bolt-like structure of the pile head 11, and the pile head is not limited to the bolt-like structure, for example, a plurality of pile heads. It is also possible to have a structure in which the reinforcing bars 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 top plate 22 is provided on the upper surface of the pile head joint peripheral body 2. The top plate 22 has an opening 22a into which a column base 51 made of, for example, a square steel pipe, which will be described later, is inserted.

An underground beam 4 is attached to the side surface of the pile head joint peripheral body 2. Of course, it is not limited to the underground beam 4, and it 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, a plurality of insertion holes are formed in the horizontal direction on the side surface of the pile head joint peripheral body 2 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 holes. 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.

A support plate 25 that supports the column base 51 is fixed to the inner wall surface of the pile head joint peripheral body 2 at a substantially intermediate position in the height direction. A pin 25a for preventing misalignment is erected on the support plate 25. The lower side of the column base 51 is inserted in the pile head joint peripheral body 2, and the pin insertion hole formed in the horizontal protrusion of the lower plate 51a provided on the lower side is inserted. The pin 25a is inserted. The support plate 25 may be an annular plate such as an inner diaphragm, and a through hole through which concrete can pass may be formed in the annular plate.

Further, for example, a circular opening 51b is formed in the lower plate portion 51a, and the upper portion (nut 11b) of the pile head 11 enters the column base portion 51 from the opening 51b. The diameter of the opening 51b and the inner diameter of the main body of the column base 51 are set so as to absorb the driving error of the pile 1 (for example, about 100 mm).

The upper side of the column base 51 protrudes above the pile head joint peripheral body 2 beyond the opening 22a. Further, an upper plate portion 51c is provided at the upper end portion of the column base portion 51. For example, a circular opening 51d is formed in the upper plate portion 51c so that the concrete 3 can be filled through the opening 51d.

Further, the base plate 5a of the pillar body 5 can be fixed to the horizontally protruding portion of the upper plate portion 51c by bolts and nuts 52. That is, in this embodiment, the column base portion 51 has a structure that is separate from the column body 5 and is connected to the column body 5. The connection is not limited to the bolts and nuts 52, and welding may be used.

When the concrete 3 is filled from the opening 51d of the column base 51, the concrete 3 is filled in the pile head joint peripheral body 2, the column base 51, and the circumference of the pile head 11. The inside of the pile head joint peripheral body 2, the inside of the column base 51, and the pile head 11 are integrated by the concrete 3. Further, due to the concrete outflow below the pile head joint peripheral body 2, the concrete 3 is also present under the pile head joint peripheral body 2. The pin 25a prevents the column base 51 from being displaced in the horizontal direction due to the input pressure of the concrete 3. Instead of the pin 25a, a misalignment preventing means using a bolt or the like can be adopted. The concrete 3 is not limited to being filled from the opening 51d of the column base 51, but the concrete 3 may be filled from the lower side of the pile head joint peripheral body 2, and the top plate 22 may be filled. An air vent may be formed. Further, instead of fully filling the concrete 3 into 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, for example, the pile head joint peripheral body 2 is lifted by a crane in a state where the column base 51 is not supported by the support plate 25, and the pile head 11 is inside the pile head joint peripheral body 2. Is descended so as to enter. Then, before inserting the column base portion 51 into the pile head joint peripheral body 2, as described above, the operator performs the fastening work with the bolts and nuts 41 by putting his / her hand through the opening 22a. By doing so, the pile head joint peripheral body 2 can be slimmed down. Of course, with the column base 51 supported by the support plate 25, the pile head 11 is lifted by a crane and lowered so that the pile head 11 enters the pile head joint peripheral body 2 and the opening 51b. You can also. When the pile head 11 is inserted into the pile head joint peripheral body 2, even if there is an error in the driving position of the pile 1, the diameter of the opening 51b formed in the column base 51 and the diameter of the opening 51b and the above Since the inner diameter of the main body of the column base 51 is set to a size that can absorb the driving error of the pile 1, the pile head joint peripheral body 2 can be installed at a predetermined position. Further, in this installation, for example, the installation height can be adjusted by interposing a member having a substantially L-shaped cross section at four places under the pile head joint peripheral body 2. Further, in this installation, a gap is formed between the pile head joint peripheral body 2 and the bottom surface of the root cutting portion 100 on the lower side. When the filled concrete 3 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 to try to leak from the gap. The concrete 3 may be dammed.

Further, as described above, one form of the method of constructing the pile foundation structure includes 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. The step of setting, the step of arranging the pile head joint peripheral body 2 so as to surround the pile head 11, and the step of locating the lower side of the column base 51 in the pile head joint peripheral body 2 and the pile head. A step of inserting the upper side of the portion 11 from the opening 51b on the lower surface side, a step of attaching an underground beam to the pile head joint peripheral body 2, and a step of inserting the concrete 3 into the pile head joint peripheral body 2 and the column base portion 51. It has a step of filling inside. 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 by fastening, for example, the member serving as the reinforcing bar when the underground beam is made of reinforced concrete is used as the pile. There is also a method of attaching to the head joint peripheral body 2. Further, the pile head joint peripheral body 2 may be arranged on the pile head 11 with the column base portion 51 set in the pile head joint peripheral body 2, or the pile head joint peripheral body 2 may be arranged on the pile head joint peripheral body 2. May be set in the pile head joint peripheral body 2 after the pillar base portion 51 is arranged on the pile head 11. Further, the filling of the concrete 3 may 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 can be 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 column base 51 and the pile head joint peripheral body 2 may be shifted to the predetermined positions with respect to the pile head 11 which is thinner than the pile 1. Therefore, the gap region required on the column base 51 side for avoiding contact with the pile head 11 can be made narrower than the gap region when the pile itself is set. 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 above-mentioned misalignment, the position of the pile head 11 can be deviated with respect to the above-mentioned deviation 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 the same depth as the pile diameter. If the pile head 11 is inserted into the pile head joint peripheral body 2 and the column base portion 51, the height of the pile head joint peripheral body 2 can be lowered.

Further, if the column base portion 51 is arranged instead of the entire column, the work of constructing the column body 5 can be performed in the construction method after the foundation work for filling the concrete 3 is completed. That is, since it is not necessary to be restricted by simultaneously performing the installation of the pillar body 5 and the foundation work, it is possible to realize a desirable construction procedure particularly in housing construction.

On the other hand, when a column whose column base is integrally provided with the column body is used, there is a restriction that the installation of the column and the foundation work are carried out at the same time. Further, when such a pillar is used, the concrete 3 can be thrown in through the gap between the opening 22a of the top plate 22 and the pillar. Further, when such a column is used, the column base of the column is fixed to the support portion 25 with a bolt or the like in the pile head joint peripheral body 2, and then the pile head joint peripheral body 2 with the column is attached. It may be arranged on the pile head 11, or the pillar may be set in the pile head joint peripheral body 2 after the pile head joint peripheral body 2 is arranged on the pile head 11. ..

4 and 5 show the pile foundation structure of another embodiment. In this pile foundation structure, a bottom plate 21 is horizontally provided inside the lower part of the pile head joint peripheral body 2, and the bottom plate 21 is formed with an opening 21a through which the pile head 11 is passed. 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 but 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.

Further, 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 the upper end screw portion 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. Further, the plate portion 13 can be fixed to the upper end of the pile 1 by welding at the site, for example. It is desirable that the plate portion 13 has a thick plate thickness. Further, the concrete 12 may be filled in the upper part of the pile 1. The lower nut 14 may be welded and fixed to the plate portion 13.

When the bottom plate 21 is provided inside the lower portion 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 can be flush with each other. It's a good one.

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 embodiments of the present invention have been described above with reference to the drawings, the present invention is not limited to those of the illustrated embodiments. 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 member 12: Concrete 13: Plate part 14: Nut 21: Bottom plate 21a: Opening 21b: Drainage hole 22: Top plate 22a: Opening 25: Support plate 25a: Pin 41: Bolt / nut 51: Column base Part 51a: Lower plate part 51b: Opening 51c: Upper plate part 51d: Opening 52: Bolt / nut 100: Root cutting location

Claims (7)

A pile driven into the ground, a pile head that is thinner than the above pile and is erected on the upper part of the pile, a steel pile head joint peripheral body that surrounds the circumference of the pile head, and the above pile head. The column base portion is provided with a column base portion that enters the body around the joint and the upper side of the pile head is inserted, and concrete that is thrown into the body around the pile head joint and the column base portion. A pile foundation structure that is separate from the column body and is connected to the column body. The pile foundation structure according to claim 1 , wherein the pile head is erected by concrete thrown into the upper side of the pile. 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, a steel pile head joint peripheral body that surrounds the circumference of the pile head, and the pile head. It is provided with a column base portion that enters the body around the joint and the upper side of the pile head is inserted, and concrete that is thrown into the body around the pile head joint and the column base portion, and the pile head is described above. A pile foundation structure characterized in that it is erected by being fixed to a plate portion attached to the upper surface of the pile. The pile foundation structure according to any one of claims 1 to 3 , wherein a bottom plate having an opening is provided inside the lower portion of the pile head joint peripheral body. The pile foundation structure according to any one of claims 1 to 4 , wherein a support portion for supporting the column base portion is provided in the body around the pile head joint. The pile foundation structure according to claim 5 , wherein the support portion includes means for regulating a horizontal displacement of the column base portion. A process of driving a pile into the ground, a process of erection of a pile head thinner than the pile on the upper side of the pile, a process of arranging a pile head joint peripheral body so as to surround the pile head, and a column. the lower side of column base unit a main body and another body is connected to the pillar main body, causes positioned around the body the pile head joint, a step of inserting the upper side of the pile head from the lower side of the opening A method for constructing a pile foundation structure, which comprises a step of putting concrete into the body around the pile head joint and the column base portion.

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