JP3511001B2 - Pile head joint structure in pile foundation - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a concrete footing (foundation of a structure) fixed to a building-civil-related structure such as a building or a bridge and embedded in the underground ground, such as a hard layer. Between the pile head and footing in the pile foundation supported by the tip support pile that is transmitted to a deep layer of the pile and supported by the head of the friction pile that is supported by the frictional force between the pile outer surface and the soil It is about structure.

[0002]

2. Description of the Related Art Conventionally, as a pile head joint structure in this type of pile foundation, a structure shown in FIGS. 7 and 8 has been generally used. That is, the underground ground 81
A concrete footing is embedded in the ground by fixing the pile 82 as a structural unit to the column and fixing it to the pillar 85 and the foundation beam 86 on the upper structure (not shown) side at the head of the pile 82. In this structure, 83 is placed, and the head of the pile 82 and the footing 83 are rigidly joined by the pile reinforcing bar 84 and concrete.

As described above, the head of the pile 82 and the footing 8
In the conventional pile head joint structure in the conventional general pile foundation that is rigidly joined with 3, when horizontal force such as earthquake acts, stress concentrates on the pile head joint that is the boundary between the two, and during a large earthquake The heads of the piles 82 and the bottoms of the footings 83 are easily damaged and damaged, which may cause damage such as collapse of the upper structure. Further, since it is a rigid joint, the stress acting on the pile head joint becomes large, and the reinforcing bar material 84 is increased,
It is necessary to increase the cross section of the pile 82 and the footing 83, which not only complicates the construction, but also increases the construction cost due to an increase in the reinforcement work. Furthermore, when damage or breakage occurs in the pile head joint, it is necessary to restore the location, but the pile head joint was supported by the pile 82 that was placed as a structural unit in the underground ground 81. Due to the substructure, there is a problem that the workability of the restoration work itself is very poor and enormous restoration costs are required.

In order to solve the problems of the conventional pile head joint structure in the conventional pile foundation as described above, a sliding member has been conventionally used, as disclosed in, for example, Japanese Unexamined Patent Publication No. 1-102124. A pile head joint structure has been proposed. As shown in FIG. 9, the pile head joint structure using the sliding material is a concrete pile 91 that is placed in the ground.
A plurality of annular reinforcing bar members 92 and a steel pipe 93 that surrounds the reinforcing bar members 92 in a state that allows the lateral deflection of the reinforcing bar members 92 are extended upward from the upper end part of the lower end part of the steel pipe 93. An annular locking protrusion 94 is provided on the concrete pile 9
Embedded connection at the upper end of 1.

A top plate 95 is provided on the upper end of the steel pipe 93.
A welding hole 96 through which the reinforcing bar 92 penetrates in a state in which lateral deflection of each of the reinforcing bar 92 is allowed by welding and fixing.
Are formed. Reinforcing bar material 92 that penetrates the top plate 95
The upper part of the concrete footing 97 is connected to the upper part of the concrete footing 97, and the sliding material 99 is interposed between the footing hardware 98 fixed to the lower part of the concrete footing 97 and the top plate 95. Is mounted and supported on the top plate 95 via a sliding member 99 so as to be relatively slidable in the horizontal direction.

[0006]

In the conventional pile foundation structure using the sliding material as described above, the horizontal ground force such as an earthquake acts to separate the underground ground and the concrete footing 97 above. When it moves, the reinforcing bar material 92 bends, and at the time of this bending, the concrete footing 97 slides horizontally on the top plate 95 via the sliding material 99 to move to the pile head joint which becomes the boundary between the two. It is possible to reduce stress concentration and suppress damage and breakage of the concrete pile 91 head and the footing 97 lower part as compared with the conventional general pile head joint structure shown in FIGS. 7 and 8.

However, in the conventional pile head joint structure in the pile foundation using the sliding material, the sliding movement amount of the footing 97 is regulated by the through hole 96 through which the reinforcing bar 92 penetrates, and the concrete pile 91 and Footing 97
Since and are connected by the reinforcing bar material 92, when an excessive horizontal force is applied due to an earthquake or the like, it is impossible to sufficiently absorb the bending moment generated at the joint portion due to the excessive horizontal force, The concrete pile 91 head part and the footing 97 lower part are inevitably damaged and damaged, and as with the conventional general structure shown in FIGS. 7 and 8, sufficient seismic resistance and seismic isolation performance cannot be secured. Further, there is a problem that the complexity of construction and the cost increase are inevitable.

The present invention has been made in view of the above situation, and suppresses the stress concentration on the pile head joint portion even if an excessive horizontal force is applied due to an earthquake or the like, and the cross section of the pile and footing is suppressed. While reducing the amount of reinforcement and bar arrangement, making construction easier and economical, prevent damage and damage to the pile head joints and maintain excellent seismic performance and seismic isolation performance even during long-term use. An object of the present invention is to provide a pile head joint structure for a pile foundation that can be used.

[0009]

In order to achieve the above-mentioned object, the pile head joint structure in the pile foundation according to the present invention is such that the head of the pile driven in the ground and the pile are separated from each other. It is a joint structure with a concrete footing fixed to the upper structure side, and a recess is formed in the head of the pile by the base plate and the rising tubular wall, and the bottom of the recess is the relative position between the pile head and the footing. An elastic member that allows rotational displacement is housed, and a shim plate for preventing wear due to relative rotational displacement between the pile head and the footing is laid on the entire upper surface of this elastic member, and on the periphery of this shim plate. Is mounted with a lateral displacement restraint member of an elastic member whose inner peripheral surface is formed as an upward taper surface, and at a position along the inner peripheral surface of the rising cylinder wall in the upper part of the recess and the opening of the recess. Peripheral position The is a scraping frame for concrete pouring of the footing, and, after hardening of the concrete, a cushioning material that can form a clearance during relative rotational displacement between the pile head and the footing is provided. The lower end portion of the cushion material provided at a position along the inner peripheral surface of the rising tubular wall is arranged on the upper surface of the lateral displacement restraining member.

According to the present invention having the above-described structure, when a horizontal force is applied due to an earthquake or the like, the pile head and the footing are relatively horizontally moved within a predetermined range within the recessed portion restricted by the cushion material. , Not only the energy at that time is absorbed by the cushion material portion, while the pile head and footing are relatively rotationally displaced in all directions by the elastic member housed in the cushion material portion and the bottom portion in the recess,
The energy at that time is absorbed by the elastic member and the cushion material. This significantly reduces the stress concentration at the joint between the pile head and footing when a horizontal force due to an earthquake or the like acts, so the cross section of the pile and footing is reduced to the necessary minimum strength, In addition, the amount of reinforcement is reduced to facilitate construction and economic efficiency, and even when an excessive horizontal force is applied, damage and damage to the pile head and footing are prevented, and excellent seismic performance and isolation It is possible to exert seismic performance.

In addition, the weight of the upper structure acts as a long-term vertical load through the footing on the elastic member housed in the recess, and when a horizontal force such as an earthquake is applied, the pile head is exposed. Due to the relative rotational displacement between the footing and the footing, a large unbalanced load acts on the elastic member. At this time, even if there is a slight gap between the inner peripheral surface of the recess and the footing, the elastic force is applied to the gap. There is a possibility that the peripheral edge of the member may be extruded and the elastic member may be cracked or damaged, and the predetermined energy absorbing function may be impaired.

In view of this point, the present invention lays a shim plate for preventing wear due to relative horizontal movement and relative rotational displacement between the pile head and the footing over the entire upper surface of the elastic member, and at the same time, the shim plate The structure adopts a configuration in which a lateral displacement restraint member of an elastic member whose inner peripheral surface is formed as an upward tapered surface is placed on the peripheral edge, and this allows elasticity during horizontal relative movement between the pile head and footing. Not only is the shim plate prevented wear and damage on the upper surface of the member, but when a long-term vertical load or an eccentric load associated with the relative rotational displacement of the pile head and footing is applied, those loads are applied to the lateral displacement restraint member. The taper surface divides the force into the elastic member side and the side force into the rising inner wall surface of the cylindrical wall, and the lower surface of the lateral displacement restraint member is received by the shim plate. Runode, so that the pressing force of the rising tube wall inner surface of the lateral displacement restricting member is enhanced. Therefore, no gap is generated between the footing and the inner peripheral surface of the recess (rising peripheral wall), and it is possible to prevent damage such as cracks due to the protrusion of the peripheral edge of the elastic member, and at the same time, the elastic member. It is also possible to reduce the corrosion and deterioration of the steel sheet, which makes it possible to stably maintain the above-described excellent seismic performance and seismic isolation performance of the elastic member for a long period of time.

Particularly, in the pile head joint structure in the pile foundation having the above-mentioned structure, as described in claim 2, a metal plate is arranged on the upper surface of the shim plate, and the lateral displacement restraint is provided at the peripheral edge of the metal plate. By adopting the configuration of forming the downward taper surface facing the upward taper surface of the member, the lateral displacement restraint member is surrounded by the inner peripheral surface of the rising cylinder wall, the shim plate, and the downward taper surface of the metal plate, and footing is performed. It prevents the lateral displacement restraint member itself from being damaged or distorted during relative horizontal movement or relative rotational displacement with the pile head, and maintains the original elastic member protrusion prevention function by this lateral displacement restraint member. Then, even after a long period of time, the predetermined seismic resistance performance and seismic isolation performance can be reliably exhibited. Further, it is possible to provide a slip function due to low friction between the metal plate and the shim plate, and it is possible to more effectively absorb the rotational force due to an earthquake or the like.

Further, according to the sixth aspect, by arranging the tip of the peripheral edge of the metal plate within the clearance, the edge of the peripheral edge of the metal plate bites into the lateral displacement restraint member to move laterally. It is possible to avoid damage to the displacement restraint member as much as possible and to stably maintain the original elastic member protrusion preventing function for a long period of time.

As the elastic member in the present invention,
It is preferable to use a rubber elastic material having an excellent compression recovery property or an elastomer material composed of a rubber base material. However, in addition to this, flow-deformable lead, a lead alloy, or a viscoelastic body may be used. .

As the constituent material of the lateral displacement restraint member, it is preferable to use fluororesin or fluororubber such as PTFE, PFA and GORE-TEX, but other than this, a copper alloy such as copper or brass can be used. May be used.

Further, as the cushion material, there is required strength as a concrete scrap frame, such as styrofoam or a corrugated cardboard material whose inner surface is waterproofed by spraying a waterproofing agent or attaching waterproof paper. It is desirable to use a material that has the above-mentioned characteristics and can be easily compressed and deformed at the time of relative horizontal movement and relative rotational displacement between the footing and the pile head.

Furthermore, the shim plate and the lateral displacement restraint member may be integrally formed of fluororesin or fluororubber.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic view showing an application example of a pile head joint structure in a pile foundation according to the present invention, which is a long-section and solid-section reinforced concrete support pile 2 formed by cast-in-place on an underground soil 1. A concrete footing 6 embedded in the ground by being fixed to a pillar 4 and a foundation beam 5 that are integrally extended downward from the building 3 that is the upper structure is placed on the top of the As shown in FIGS. 2 and 3, it is joined to the head portion 2A of the pile 2 via a support structure 7 described later.

The support structure 7 is constructed as follows. That is, as clearly shown in FIG. 4, a metal base plate 8 and upward from the base plate 8 on the top of the head 2A of the support pile 2 set at a level slightly lower than the excavation surface of the pile construction. A shoe 10 composed of a rising cylindrical wall 9 having a square shape (or rectangular shape or circular shape) in plan view, which is integrally fixed and projected with a length reaching the excavation surface for pile construction, is mounted, and the shoe 10 is mounted. By fixing to the ground 1 with the outer moat concrete 11, the recessed portion 12 opening upward is formed in the head portion 2A of the pile 2.

At the bottom of the recess 12, the head 2 of the pile 2 is provided.
An elastic member 13 that allows relative rotational displacement between A and the concrete footing 6 is housed in a state where the outer peripheral surface thereof rises and is in close contact with the inner peripheral surface of the peripheral wall 9, and the entire upper surface of the elastic member 13 is covered. A resin shim plate 14 is installed to prevent wear of the elastic member 13 due to relative horizontal movement and relative rotational displacement between the head 2A of the pile 2 and the footing 6. On the peripheral portion of the resin shim plate 14,
It is made of fluororesin or fluororubber such as PTFE, PFA, GORE-TEX, and has an inner peripheral surface 15 thereof.
The lateral displacement restraint member 15 of the elastic member 13 in which a is formed in the upward tapered surface is placed, and the metal plate 16 is arranged on the upper surface of the shim plate 14.
A downward taper surface 16a facing the upward taper surface 15a of the lateral displacement restraint member 15 is formed on the peripheral edge portion of the metal plate 16, whereby the lateral displacement restraint member 15 rises when the shoe 10 rises. It is surrounded by the inner peripheral surface of the peripheral wall 9, the peripheral edge of the shim plate 14, and the downward taper surface 16 a of the metal plate 16.

Further, at a position along the inner peripheral surface of the rising cylindrical wall 9 in the upper portion of the recess 12 formed by the shoe 10, for example, styrofoam or a corrugated cardboard material whose inner surface is waterproof can be deformed by compression. A rectangular tubular cushion material 17 whose lower end is located on the upper surface of the lateral displacement restraining member 15 is provided, and at the periphery of the opening of the recess 12, for example, styrofoam or the upper surface is provided. A cushion material 18, which is made of a material that can be compressed and deformed such as a waterproof corrugated cardboard material, and whose lower surface is in contact with the pile excavation surface and has a square shape in a plan view, is provided. These cushion materials 17 and 18 are a scrap frame for placing concrete when the concrete footing 6 is produced, and the head 2 of the pile 2 after the concrete is hardened.
A clearance is formed at the time of relative horizontal movement and relative rotational displacement between A and the footing 6.

Here, as the elastic member 13, it is preferable to use a rubber elastic material having an excellent compression-restoration characteristic or an elastomer material composed of a rubber base material.
Flow-deformable lead, lead alloy, viscoelastic body, or the like may be used.

In the pile head joint structure in the pile foundation constructed as described above, when the horizontal force due to an earthquake or the like acts, the head 2A of the pile 2 and the footing 6 are restricted by the cushion material 17. While moving relatively horizontally within a predetermined range in the recess 12, the energy at that time is not only absorbed by the cushion material 17, but also the elasticity stored in the cushion materials 17, 18 and the bottom of the recess 12 is accommodated. Head 2A of foot 2 and footing 6 by member 13
While and are relatively rotationally displaced in all directions, the energy at that time is absorbed by the elastic member 13 and the cushion members 17 and 18. This significantly reduces the stress concentration on the joint between the pile head 2A and the footing 6 when a horizontal force due to an earthquake or the like is applied, so that the cross section of the pile 2 and the footing 6 has the minimum necessary strength. It is possible to prevent damage and breakage of the pile head 2A and the footing 6 even when an excessive horizontal force is applied, while reducing the amount of reinforcement and reducing the amount of reinforcement to facilitate the construction and reduce the cost. It is possible to exert excellent seismic resistance and seismic isolation performance.

A shim plate 14 is laid on the entire upper surface of the elastic member 13 housed in the recess 12, and the elastic member 13 has an upward tapered surface 15a on the peripheral edge of the shim plate 14. Since the lateral displacement restraint member 15 is mounted, the shim plate 14 not only prevents wear and damage of the upper surface of the elastic member 13 when the pile head 2A and the footing 6 move horizontally relative to each other. When a long-term vertical load or an eccentric load due to relative rotational displacement between the pile head 2A and the footing 6 is applied to the elastic member 13, those loads are applied to the tapered surface 1 of the lateral displacement restraint member 15.
5a divides the elastic member 13 into a component of a pressing force to the elastic member 13 side and a pressing force to the inner peripheral surface side of the rising cylindrical wall 9 laterally.
Therefore, the pressing force of the lateral displacement restraint member 15 on the inner peripheral surface side of the rising cylindrical wall 9 is increased.

Therefore, even when an earthquake or the like occurs,
There is no gap between the footing 6 and the inner peripheral surface of the recess 12 (the rising peripheral wall (9)), and the elastic member 13
It is possible to prevent damage such as cracks due to the protrusion of the peripheral portion of the elastic member 1 and at the same time reduce corrosion and deterioration of the elastic member 13, and thereby the elastic member 1
It is possible to stably maintain the above-described excellent seismic performance and seismic isolation performance according to No. 3 for a long period of time.

In particular, the lateral displacement restraint member 15 is surrounded by the inner peripheral surface of the rising cylinder wall 9, the shim plate 14, and the downward taper surface 16a of the metal plate 16, so that the footing 6 and the pile head 2A are relatively opposed to each other. It prevents the lateral displacement restraint member 15 itself from directly contacting concrete and being damaged or deformed by distortion during horizontal movement or relative rotational displacement.
The original elastic member protrusion preventing function of the lateral displacement restraint member 15 can be more stably maintained, and the predetermined seismic resistance performance and seismic isolation performance can be more reliably exhibited even after a long period of time.

In the above embodiment, the downward taper surface 16a facing the upward taper surface 15a of the lateral displacement restraint member 15 is formed at the peripheral edge of the metal plate 16, but as shown in FIG. 6, even if the flat metal plate 16 is laid on the entire upper surface of the shim plate 14 and the lateral displacement restraint member 15 is placed on the peripheral edge of the flat metal plate 16, as shown in FIG. The lateral displacement restraint member 1 is provided on the peripheral edge of the shim plate 14.
5 may be placed, and the flat metal plate 16 may be placed on the upper surface of the shim plate 14 excluding the placement portion. In either case, the flat metal plate 16 is almost the same as the above-described embodiment. The elastic member can exert a protruding preventing function.

[0029]

As described above, according to the present invention, when a horizontal force due to an earthquake or the like is applied, relative horizontal movement within a predetermined range between the pile head and footing and relative rotational displacement in all directions are allowed. Since it is possible to absorb energy while significantly reducing the stress concentration at the joint between the pile head and footing, the cross section of the pile and footing is reduced to the minimum necessary strength, and Excellent seismic performance by preventing damage and damage to the pile head and footing even when an excessive horizontal force is applied, while reducing the amount of bar arrangement to facilitate construction and economic efficiency (cost reduction). It is possible to exert seismic isolation performance.

Moreover, a special structure for protecting the elastic member is adopted, such as laying a wear preventing shim plate and placing an elastic member lateral displacement restraining member having an upward taper surface on the periphery of the shim plate. By
In addition to preventing abrasion and damage to the top surface of the elastic member during relative horizontal movement and relative rotational displacement between the pile head and footing,
It is possible to prevent damage such as cracks due to the protrusion of the peripheral edge of the elastic member under the condition that an unbalanced load acts due to long-term vertical load and relative rotational displacement between the pile head and footing, and reduce corrosion and deterioration. There is an effect that the above-mentioned excellent seismic resistance performance and seismic isolation performance due to the elastic member can be stably maintained for a long period of time.

[Brief description of drawings]

FIG. 1 is a schematic view showing an application example of a pile head joint structure in a pile foundation according to the present invention.

FIG. 2 is an enlarged front view of the circled portion of FIG.

FIG. 3 is a plan view of FIG.

FIG. 4 is an enlarged semi-longitudinal sectional view showing details of a pile head joint structure.

FIG. 5 is an enlarged semi-longitudinal sectional view showing details of a pile head joint structure according to another embodiment of the present invention.

FIG. 6 is an enlarged semi-longitudinal sectional view showing details of a pile head joint structure according to another embodiment of the present invention.

FIG. 7 is an enlarged vertical cross-sectional view of an essential part showing a pile head joint structure in a conventional general pile foundation.

FIG. 8 is a plan view of FIG.

FIG. 9 is an enlarged vertical cross-sectional view of a main part showing a pile head joint structure in a conventionally proposed pile foundation.

[Explanation of symbols]

1 underground ground 2 Reinforced concrete support piles 2A pile head 3 buildings (superstructure) 6 Concrete footing 8 base plate 9 rising cylinder wall 12 recess 13 Elastic member 14 Shim Plate 15 Lateral displacement restraint members 15a Upward tapered surface 16 metal plate 16a Downward taper surface 17,18 Cushion material

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-10-168906 (JP, A) JP-A-10-176335 (JP, A) JP-A-9-32345 (JP, A) JP-A-7- 292690 (JP, A) JP 2000-46195 (JP, A) JP 11-148143 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) E02D 27/00-27 / 52

Claims (6)

(57) [Claims] 1. A joint structure of a head of a pile driven in the ground and a concrete footing separated from the pile and fixed to the upper structure side, wherein a base plate and a base plate are attached to the head of the pile. A recess is formed by the rising tubular wall, and an elastic member that allows relative rotational displacement between the pile head and the footing is accommodated in the bottom of the recess, and the entire upper surface of the elastic member has a pile head. A shim plate for preventing wear due to relative rotational displacement with the footing is laid, and on the peripheral edge of this shim plate, a lateral displacement restraint member of an elastic member having an inner peripheral surface formed in an upward tapered surface is placed, Further, in the upper part of the recess, along the inner peripheral surface of the rising cylinder wall and in the peripheral position of the opening of the recess, there is a waste casting frame for concrete placing of the footing, and after concrete hardening, piles. Is provided with a cushion material capable of forming a clearance at the time of relative rotational displacement between the foot portion and the footing. Of these cushion materials, the lower end portion of the cushion material provided at a position along the inner peripheral surface of the rising cylinder wall has the above-mentioned lateral direction. A pile head joint structure in a pile foundation, which is arranged on the upper surface of a displacement restraint member. 2. A metal plate is disposed on the upper surface of the shim plate, and a downward taper surface facing the upward taper surface of the lateral displacement restraint member is formed on a peripheral portion of the metal plate. A pile head joint structure in the pile foundation according to Item 1. 3. The pile head joint structure for a pile foundation according to claim 1, wherein the elastic member is made of a rubber elastic material having an excellent compression restoring property or an elastomer material made of a rubber base material. . 4. The lateral displacement restraint member is made of a fluororesin or a fluororubber material.
The pile head joint structure in the pile foundation according to any one of 1 to 3. 5. The cushion material is styrofoam,
The pile head joint structure for a pile foundation according to any one of claims 1 to 4, which is made of a material that is elastically compressible and deformable, such as a cardboard material having an inner surface waterproofed. 6. The pile head joint structure for a pile foundation according to claim 2, wherein a tip of a peripheral edge portion of the metal plate is arranged in the clearance.