JP2003129498A - Jointing structure between foundation pile and footing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a jointing structure which is equipped with good workability, and allows a footing to float up from a head part of a foundation pipe when great overturning moment acts on a building. SOLUTION: A steel pipe 10 for jointing is fixedly provided in the head part of the foundation pile 22 of reinforced concrete construction, so as to form a protrusion which protrudes upward from the head part of the foundation pile 22. In placing of concrete for the footing 26 of the reinforced concrete construction, the concrete surrounds an upper part of the steel pipe 10 so as to be brought into direct contact with an outer peripheral surface of the upper part of the steel pipe 10. In the action of a load for floating up the footing 26, sliding occurs on a contact surface between the concrete of the footing 26 and the outer peripheral surface of the upper part of the steel pipe 10, so that the footing 26 can be displaced relatively upward with respect to the foundation pile 22. Shearing resistance is imposed on the steel pipe 10. A shock- absorbing material 30, which is interposed between an upward surface of the head part of the foundation pile 22 and a downward surface of a bottom part of the footing 26, absorbs a shock when the footing 26, which floats up from the foundation pile 22, returns to an original position.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a joint structure between a reinforced concrete foundation pile and a reinforced concrete footing supported by the foundation pile.

[0002]

2. Description of the Related Art In a pile foundation structure in which a footing is supported by a foundation pile, a footing is generally rigidly joined to the head of the foundation pile, but there is also a structure in which both are not rigidly joined. . For example, in a tower-shaped building, when the ground causes horizontal acceleration due to an earthquake, a large overturning moment may act on the building and one side of the building may try to float up. If the base pile and the foundation pile are rigidly joined, a large pulling force acts on the foundation pile. As described above, in order to withstand a large overturning moment that pulling force acts on the foundation pile, the foundation beam formation, footing, and column width of the building must be increased, and the foundation pile must be pulled out. In order to secure a large anti-friction force on the peripheral surface of the pile, the length of the pile must be increased, which causes various inconveniences such as an increase in material costs and construction costs.

In order to avoid these disadvantages, the footing is allowed to float up from the head of the foundation pile when a large overturning moment is applied to the building without rigidly connecting the foundation pile and the footing. A bonded structure has been proposed. According to this joint structure, one side of the building to which a large overturning moment has acted is slightly lifted, so that it is possible to prevent an excessive load from acting on the foundation and lower story pillars of the building, and also the foundation piles. Since the pulling force does not act on the foundation, it is possible to reduce the size of the foundation and the column width, which in turn can improve the earthquake resistance of the building and reduce the cost.

[0004]

As described above, the joint structure that allows the footing to float above the head of the foundation pile when a large overturning moment acts on the building is such that the footing moves horizontally with respect to the foundation pile. The structure must resist shearing forces to prevent displacement. In addition, the structure must be such that the raised footing can rebound and absorb the impact when it collides with the head of the foundation pile. Furthermore, it is desired to have a structure capable of appropriately controlling the amount of floating footing. This type of joint structure that has been proposed in the past merely presents the concept of allowing footing to float above the head of the foundation pile, satisfies the requirements listed above, and is well implemented. A joining structure with good properties has not been proposed so far.

The present invention has been made in view of the above circumstances, and an object of the present invention is to find a joining structure that allows footings to float above the heads of foundation piles when a large overturning moment acts on a building. It is to provide a joint structure between a foundation pile and a footing, which satisfies a number of requirements to be satisfied, and has good workability.

[0006]

In order to achieve the above object, the present invention provides a joint structure between a reinforced concrete foundation pile and a reinforced concrete footing supported by the foundation pile. The steel pipe for joining is integrally fixed to the portion, the steel pipe for joining has a constant cross section, has a smooth outer peripheral surface, and is fixed so that its axial center extends in the vertical direction, When the concrete of the foundation pile is placed therein, a convex portion protruding upward from the head of the foundation pile is formed, and the concrete of the footing surrounds the upper portion of the joining steel pipe. Is placed so as to directly contact the outer peripheral surface of the upper part, and when a load for lifting the footing is applied,
The footing can be displaced relatively upward relative to the foundation pile by causing a slip on the contact surface between the concrete of the footing and the outer peripheral surface of the upper portion of the joining steel pipe, Between the upward surface of the head of the foundation pile defined at the tip of the convex portion or the periphery and the downward surface of the bottom portion of the footing facing the upward surface, a shock absorbing material is interposed. The shock absorbing material absorbs a shock when the footing displaced so as to float from the foundation pile is restored. Further, the present invention is a joint structure between a reinforced concrete foundation pile and a reinforced concrete footing supported by the foundation pile, wherein a steel pipe for joining is integrally fixed to the bottom of the footing, and The steel pipe has a constant cross-section, has a smooth outer peripheral surface, and is fixed so that its axial center extends in the vertical direction, and the footing concrete is placed therein, whereby the footing is formed. Forming a convex portion protruding downward from the bottom of the, the concrete of the foundation pile is placed so as to directly contact the outer peripheral surface of the lower part of the steel pipe for joining, surrounding the lower part, When a load that lifts the footing acts, the footing causes the slipping to occur in the contact surface between the concrete of the foundation pile and the outer peripheral surface of the lower portion of the joining steel pipe. The bottom face of the bottom of the footing, which is defined at the tip of the convex portion or around the bottom face, and the foundation pile facing the bottom face. A shock absorbing material is interposed between the head and the upward surface of the head so that the shock absorbing material absorbs a shock when the footing displaced so as to float from the foundation pile is restored. It is characterized by The joining steel pipe also has a role as a mechanism for resisting shearing force.

According to the joining structure of the present invention, the work of placing the steel pipe for joining and the work of interposing the impact absorbing material in the work normally required for constructing the reinforced concrete foundation pile and footing. By simply adding and, it is possible to obtain a joint structure that allows the footing to lift from the head of the foundation pile when a large overturning moment acts on the building, and the addition work is very easy. Therefore, it is possible to provide a joint structure between the foundation pile and the footing, which satisfies various requirements required for this kind of joint structure and has good workability.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the accompanying drawings. 1A and 1B are perspective views showing a concrete example of a joining steel pipe used for a joining structure between a foundation pile and a footing according to an embodiment of the present invention, and FIG. 2 is a first embodiment of the present invention. 3 is a cross-sectional view of a joint structure between a foundation pile and a footing according to the embodiment of the present invention, FIG. 3 is a perspective view of a shock absorber retainer used in the joint structure between a foundation pile and a footing according to an embodiment of the present invention, FIG. 4 is a cross-sectional view of a joint structure between a foundation pile and a footing according to a second embodiment of the present invention, and FIG. 5 is a sectional view between a foundation pile and a footing according to a third embodiment of the present invention. FIG. 6 is a sectional view of the joint structure, and FIG. 6 is a sectional view of the joint structure between the foundation pile and the footing according to the fourth embodiment of the present invention.

A joint structure between a foundation pile and a footing according to the present invention is a joint structure between a reinforced concrete foundation pile and a reinforced concrete footing supported by the foundation pile, which is large in a building. It is a joint structure that allows the footing to lift up from the head of the foundation pile when an overturning moment acts.

This joining structure uses a steel pipe for joining, which is fixedly mounted on one of the foundation pile and the footing, so that it can be easily constructed without requiring a troublesome construction work. As the steel pipe for joining, use a steel pipe with a constant cross-section and a smooth outer peripheral surface, which is fixed to the head of the foundation pile or the bottom of the footing so that its axis extends vertically. To do.

1A and 1B show specific examples of the joining steel pipe 10. As shown in the figure, as the joining steel pipe 10,
A round steel pipe may be used (a in FIG. 1) or a square steel pipe (b in FIG. 1). In either case, the joining steel pipe 10 is a steel pipe having sufficient strength that can function as a shear resistance mechanism that suppresses relative horizontal displacement of the footing relative to the foundation pile. In order to firmly fix the joining steel pipe 10 to the foundation pile or the footing, here, when fixing the joining steel pipe 10 to the footing, the joining steel pipe 10 is assembled to the reinforcing bar of the footing and then the concrete of the footing is attached. When the steel pipe is fixed to the foundation pile, the joining steel pipe 10 is assembled to the reinforcing bar of the foundation pile and then the concrete of the foundation pile is poured. FIG. 1 also shows a specific example of how to attach the steel pipe for joining 10 to the reinforcing bar when the steel pipe 10 for bonding is fixedly installed. Reference numerals 12 and 14 in the figure are reinforcing rings prepared by cutting a steel pipe into short pieces for concrete shear reinforcement of pile heads. After welding the reinforcing rings 12 and 14 to the reinforcing bars of the foundation pile at the time of construction, arranging the auxiliary reinforcing bars 16 in a cross beam shape and welding the auxiliary reinforcing bars 16 to the joining steel pipe 10 and the reinforcing rings 12 and 14. Therefore, the joining steel pipe 10 may be assembled to the reinforcing bar of the foundation pile. When assembling the joining steel pipe 10 to the footing rebar, the same assembling method can be used. However, the joining steel pipe 10
The method of assembling the base pile or the reinforcing bar of the footing is not limited to this, and an appropriate assembling method may be adopted depending on the specific method of assembling the reinforcing bar of the foundation pile or the footing. However, the specific example shown in FIG. 1 is a particularly suitable method in that the construction is easy and the steel tube 10 for an electrode can be firmly fixed. Note that the embodiment of the present invention described below uses the joining steel pipe 10 made of a round steel pipe shown in FIG.

The joining structure 20 according to the first embodiment of the present invention shown in FIG. 2 is a foundation pile 2 made of reinforced concrete.
2 and a footing 26, which is also made of reinforced concrete and supports the base ends of the columns 24, are joined together.
Are integrally fixed to the head of the foundation pile 22. In order to fix the joining steel pipe 10 to the foundation pile 22 at the time of construction, as described above with reference to FIG. 1, the foundation pile 22 is provided through the auxiliary reinforcing bar 16 (see FIG. 1) in which the joining steel pipe 10 is assembled in the girder. After fixing the concrete of the foundation pile 22 after fixing it to the main reinforcement 28 of the foundation pile 22, the concrete of the foundation pile 22 is also poured into the joining steel pipe 10 at that time, so that the joining steel pipe 10 is formed into the foundation pile. It is integrally fixed to 22. Therefore, when the foundation pile 22 is completed, the joining steel pipe 10 forms a convex portion protruding upward from the head of the foundation pile 22. Further, in the embodiment of FIG. 2, the concrete to be placed in the joining steel pipe 10 is such that the surface of the concrete is flush with the upper end of the joining steel pipe 10. The surface defines a horizontal plane.

The foundation pile 22 may be a ready-made pile manufactured in a factory or a cast-in-place pile manufactured on site. In either case, the steel pipe for joining 10 is integrally fixed to the head of the foundation pile 22 in the process of manufacturing the foundation pile 22.

After the foundation pile 22 is located at a predetermined position on the site, a shock absorber retainer is attached to the head of the foundation pile 22. The shock absorbing material is provided between the upward surface of the head of the foundation pile 22 defined at the tip of the convex portion made of the joining steel pipe 10 or the periphery thereof and the downward surface of the bottom portion of the footing 26 facing the upward surface. The footing 26, which is interposed and displaced so as to be lifted from the foundation pile 22, serves to absorb a shock when the footing 26 returns to its original position. In the illustrated example, the sand 30 is used as the shock absorbing material, but it is also possible to use particles other than sand, and a viscous body or a rubber body may be used. The shock absorber retainer has the function of preventing the granules or viscous bodies from flowing out when using a granule or a viscous body as the shock absorber, and when using a rubber body as the shock absorber. Serves to position the rubber body and control the amount of deformation.

In the embodiment shown in FIG. 2, the shock absorbing material 30 is used.
Is interposed between the horizontal surface forming the upper end surface of the convex portion of the foundation pile 22 formed of the joining steel pipe 10 and the concrete surface of the bottom portion of the footing 26 facing the convex plane of the foundation pile 22 and surrounding the convex portion of the foundation pile 22. Is also interposed between the horizontal surface and the concrete surface at the bottom of the footing 26 facing it. Correspondingly, two shock absorber retainers are used. Among them, the first retainer 32 is formed as a shallow circular dish-shaped container having the same diameter as the diameter of the convex portion of the foundation pile 22, and as shown in FIG. Attach to the top surface of. Also, the second
The retainer 34 is formed as a shallow square dish-shaped container having a hole corresponding to the outer periphery of the head of the foundation pile 22. The second retainer 34 has its bottom plate as shown in FIG. Is attached to the head of the foundation pile 22 so as to be continuous with the horizontal plane around the joining steel pipe 10 of the head of the foundation pile 22. The first retainer 32 may be made of a thin metal plate or a thick soft plastic sheet, and the second retainer 34 may be made of a thick metal plate. Further, the retainers 32 and 34 can be manufactured using other materials.

If the shock absorber retainers 32 and 34 are arranged at predetermined positions on the foundation pile 22 as shown in FIG.
The retainers 32 and 34 are filled with the shock absorbing material 30. Then, the reinforcing bars (not shown) and the form (not shown) of the footing 26 are assembled, and concrete is poured. When the concrete of the footing 26 is cast, the concrete surrounds the upper part of the joining steel pipe 10 and is directly contacted with the outer peripheral surface of the upper part. As mentioned above,
Since the outer peripheral surface of the joining steel pipe 10 is smooth, the concrete of the footing 26 adheres to the outer peripheral surface of the joining steel pipe 10 with some adhesive force, but does not completely adhere to the outer peripheral surface. Therefore, when an earthquake occurs and a falling moment acts on the building and a load that lifts the footing 26 acts, the footing 26
By causing a slip on the contact surface between the concrete and the outer peripheral surface of the upper portion of the joining steel pipe 10, the footing 26 can be displaced upward relative to the foundation pile 22,
Therefore, the footing 26 can be displaced so as to float above the foundation pile 22. Then, the shock when the footing 26 displaced in this way returns to its original position
Absorbed by 0. In addition, in FIG. 2, the steel pipe 10 for joining is shown.
The length of embedding in the foundation pile 22 that is embedded in the fixed state is indicated by L1, and the length of the footing 26 that is embedded in the non-fixed state is indicated by L2. As is clear from the figure, the joining steel pipe 10
The length L1 on the embedded side in the fixed state is set to be sufficiently longer than the embedded length L2 on the embedded side in the non-fixed state. Further, as shown in the figure, if the stud bolts 18 are provided in advance on the outer peripheral surface of the joining steel pipe 10 on the embedded side in the fixed state, it is advantageous because the fixing force can be further strengthened.

In the joint structure 20 described above, the impact absorbing material 30 is interposed at two places, that is, the joint steel pipe 1
0 between the horizontal plane forming the upper end surface of the convex portion of the foundation pile 22 and the concrete surface of the bottom portion of the footing 26 facing it, and the horizontal plane around the convex portion of the foundation pile 22 and the facing footing. It is interposed between the concrete surface of the bottom of 26. However, depending on the load conditions, it is not necessary to install the impact absorbing material 30 at both of these locations, and in some cases it may be sufficient to provide it at only one location. In such a case, a spacer formed of a foamed plastic plate or the like is attached to the footing 26 instead of the retainer at a place where the shock absorber 30 is not interposed.
The concrete should be placed. As a result, the upper surface of the head of the foundation pile 22 and the footing 26
Since there is no direct contact with the downward surface of the bottom of the shock absorber 30, the shock absorbing material 30 can effectively function.

The joint structure 40 according to the second embodiment of the present invention shown in FIG. 4 is a foundation pile 2 made of reinforced concrete.
2 and the footing 26 of the same reinforced concrete structure that supports the base ends of the pillars 24 are joined, and the big difference from the embodiment of FIG. 2 is that the joining steel pipe 10 is not attached to the head of the foundation pile 22. Rather, it is integrally fixed to the bottom of the footing 26. The connection state between the joining steel pipe 10 and the foundation pile 22 is the same as the connection state between the joining steel pipe 10 and the footing 26 in the embodiment of FIG. In the following description of the joining structure 40 of FIG. 4, the same or corresponding parts as those of the joining structure 20 of FIG. 2 are designated by the same reference numerals, and detailed description of such parts is omitted. .

In order to construct the joint structure according to the embodiment of FIG. 4, first, after the foundation piles 22 have been laid, the pile heads are hung in a concave shape so that the heads of the foundation piles 22 are
A recess having a size that can accommodate the lower portion of the joining steel pipe 10 is formed. Then, after inserting the retainer 42 and the impact absorbing material 30 in this recess, the lower part of the joining steel pipe 10 is accommodated, and the joining steel pipe 10 is installed on the head of the foundation pile 22. Then, the foundation pile 22 is finally completed by additionally placing concrete of the foundation pile 22 in the gap between the lower peripheral surface of the joining steel pipe 10 and the inner wall of the recess. Note that the retainer can be omitted if there is no risk of the shock absorber interposed in the recess of the foundation pile disappearing in the pile body.

When the concrete of the foundation pile 22 is replenished and placed, the concrete is placed so as to surround the lower portion of the joining steel pipe 10 and directly contact the outer peripheral surface of the lower portion. As described above, since the outer peripheral surface of the joining steel pipe 10 is smooth, the concrete of the foundation pile 22 adheres to the outer peripheral surface of the joining steel pipe 10 with some adhesive force, but is completely fixed to the outer peripheral surface. There is no end. As a result, an earthquake occurs and a falling moment acts on the building,
When a load that lifts the footing 26 is applied, slippage occurs on the contact surface between the concrete of the foundation pile 22 and the outer peripheral surface of the lower portion of the joining steel pipe 10, so that the joining foot of the joining steel pipe 10 is fixed. Can be displaced upwards relative to the foundation pile 22, thus allowing the footing 26 to be displaced above the foundation pile 22. In FIG. 4, the length of embedding the joining steel pipe 10 in the footing 26 embedded in the fixed state is indicated by L1, and the length of the foundation pile 22 embedded in the non-fixed state is indicated by L2.
Indicated by. As is apparent from the figure, the embedding length L1 on the side where the joining steel pipe 10 is embedded in the fixed state is set sufficiently longer than the embedding length L2 on the side embedded in the non-fixed state. ing. Further, as shown in the figure, if the stud bolts 18 are provided in advance on the outer peripheral surface of the joining steel pipe 10 on the embedded side in the fixed state, it is advantageous because the fixing force can be further strengthened.

The foundation pile 22 may be a ready-made pile manufactured in a factory or a cast-in-place pile manufactured in the field. In the case of a ready-made pile, after driving it into a predetermined position in the site, the joining steel pipe 10 is attached to the head as described above. In the case of a cast-in-place pile, it is installed in the site. The steel pipe 10 for joining is attached to the head of the steel pipe 10 at the predetermined position as described above.

After the foundation pile 22 is located at a predetermined position on the site, a shock absorber retainer (second retainer) formed as a shallow square dish-shaped container having a hole corresponding to the outer circumference of the head of the foundation pile 22 in the center is provided. ) 44, the bottom plate of which is the foundation pile 2
The second head is attached to the head of the foundation pile 22 so as to be continuous with the horizontal plane around the joining steel pipe 10. The shock absorber retainer 44 may be made of a thick metal plate or the like, and may be made of other materials.

Then, the second member mounted on the head of the foundation pile 22.
The retainer 44 is filled with the shock absorbing material 30. After the joining structure 40 of FIG. 2 is completed, the impact absorbing material 30 faces the downward surface of the bottom of the footing 26 defined at the tip of the convex portion formed of the joining steel pipe 10 or the periphery thereof, and the downward surface. The footing 26, which is placed between the foundation pile 22 and the upward surface of the head of the foundation pile 22, serves to absorb the shock when the footing 26 displaced from the foundation pile 22 is displaced. As in the case of the embodiment, granules, viscous bodies, rubber bodies, etc. can be used as the shock absorbing material 30.

Subsequently, the reinforcing bars of the footing 26 (not shown)
And a formwork (not shown), and further, an auxiliary reinforcing bar assembled in a cross girder similar to the auxiliary reinforcing bar 16 shown in FIG. By arranging it between the rebar and welding them,
The joining steel pipe 10 is joined to the reinforcing bar of the footing 26. Subsequently, the concrete of the footing 26 is poured, and at this time, the concrete of the footing 26 is also placed in the joining steel pipe 10, so that the joining steel pipe 10 is integrally fixed to the footing 26. Therefore, when the footing 26 is completed, the joining steel pipe 10 forms a convex portion protruding downward from the bottom portion of the footing 26.

The joint structure 40 is completed as described above. In this joint structure 40 as well, as in the joint structure 20 of FIG. 2, the impact absorbing material 30 is interposed at two positions, that is, the horizontal plane forming the lower end surface of the convex portion of the footing 26 formed of the joint steel pipe 10. And the concrete surface of the head of the foundation pile 22 facing it, and between the horizontal surface around the convex portion of the footing 26 and the concrete surface of the head of the foundation pile 22 facing it. ing. However, depending on the load conditions, it may not be necessary to install the shock absorbing material 30 at both of these locations, and it may be sufficient to install it at only one location. In such a case, a spacer formed of a foamed plastic plate or the like may be mounted in place of the retainer at a place where the shock absorber 30 is not interposed, and then concrete may be poured. As a result, the upper surface of the head of the foundation pile 22 and the lower surface of the bottom of the footing 26 do not come into direct contact with each other, so that the shock absorber 30 can effectively function.

In the embodiment of FIGS. 2 and 4 described above, the footing 26 can be lifted from the head of the foundation pile 22 when an earthquake occurs and a large overturning moment acts on the building. No large pulling force is transmitted from 26 to the foundation pile 22. However, rather than a structure in which the pulling force is not transmitted at all, rather than transmitting a pulling force of an appropriate size, the amount of lifting of the footing 26 can be appropriately controlled by the reaction force from the foundation pile 22 with respect to the pulling force. Often desirable. In this regard, in the joining structure 20 according to the embodiment of FIG. 2, the adhesive force between the outer peripheral surface of the joining steel pipe 10 and the concrete of the footing 26 is different, and in the joining structure 40 according to the embodiment of FIG. Since the adhesive force between the outer peripheral surface of the steel pipe 10 and the concrete of the foundation pile 22 functions as a slight resistance force for suppressing the lifting of the footing 26, the footing 26 is
The amount of uplifting is controlled.

However, depending on the load condition, a further control force for lifting may be required. The embodiment of FIGS. 5 and 6 described below is an embodiment suitable for such a case.

The joint structure 60 according to the embodiment shown in FIG. 5 and the joint structure 80 according to the embodiment shown in FIG.
Both correspond to modifications of the bonding structure 20 according to the first embodiment shown in FIG. 2, and in the following description, only the differences from the bonding structure 20 of FIG. 2 will be described. To do.

In the joint structure 60 shown in FIG. 5, the main bar 28 of the foundation pile 22 is long so as to extend upward from the head of the foundation pile 22 and surrounds the upper end portion of the main bar 28 extending upward. By placing the concrete of the footing 26 in this manner, the foundation pile 22 and the footing 26 are inserted through the main bar 28.
And are connected. According to this structure, due to the adhesive force between the concrete of the footing 26 and the main reinforcement 28 of the foundation pile 22, a certain pulling force is transmitted from the footing 26 to the foundation pile 22 through the main reinforcement 28, and
The reaction force from the foundation pile 22 with respect to the pulling force acts as a control force for the lifting of the footing 26, so that the lifting amount of the footing 26 is controlled. Therefore, the structure of FIG.
To extend upward from the head of the foundation pile 22 and
By connecting the foundation pile 22 and the footing 26 via 8, the resistance of the footing 26 against rising can be adjusted.

In the joint structure 80 of FIG. 6, a PC steel wire 84 having an anchor 82 connected to the lower end is fixed in the foundation pile 22. The PC steel wire 84 extends vertically,
The upper end portion passes through the steel pipe for joining 10 to form the foundation pile 22.
Extends upwards from the head. On the other hand, footing 26
The notch 86 is formed in the notch 86, and the PC steel wire 8 is attached to the PC steel wire fixing iron plate 88 arranged at the bottom of the notch 86.
The upper end of No. 4 is fastened and the prestress is introduced into the PC steel wire 84. Therefore, the joint structure 80 of FIG.
2 and the footing 26 are connected via a PC steel wire 84, and the footing 2 is connected via this PC steel wire 84.
A certain amount of pulling force is transmitted from 6 to the foundation pile 22, and the amount of lifting of the footing 26 is controlled by the reaction force from the foundation pile 22 to the pulling force. Further, by adjusting the magnitude of the prestress introduced into the PC steel wire 84, it is possible to adjust the resistance of the footing 26 against lifting.

According to the above-described embodiment, the work of interposing the impact absorbing material 30 is performed by placing the impact absorbing material retainer 32 mounted on the head of the foundation pile 22 before placing the concrete of the footing 26. , 34, 42, 44, the shock absorbing material filling space is filled with the shock absorbing material 30 made of particles, viscous material, or rubber material, and at that time, the shock absorbing material is accommodated. Since the space is open to the outside, the filling operation can be carried out very easily.

[0032]

As is apparent from the above description, the joint structure between the reinforced concrete foundation pile according to the present invention and the reinforced concrete footing supported by the foundation pile is provided at the head of the foundation pile. The joining steel pipe is integrally fixed, and the joining steel pipe has a constant cross section, has a smooth outer peripheral surface, and is fixed so that its axial center extends in the vertical direction. The concrete of the foundation pile is placed in the, thereby forming a convex portion projecting upward from the head of the foundation pile, the concrete of the footing surrounds the upper portion of the joining steel pipe, It is placed so as to be in direct contact with the outer peripheral surface of the upper part, and when a load that lifts the footing acts, slips on the contact surface between the concrete of the footing and the outer peripheral surface of the upper part of the joining steel pipe. When the footing occurs, the footing can be displaced relatively upward with respect to the foundation pile, and an upward surface of the head of the foundation pile and a downward surface of the bottom of the footing that faces the upward surface. A shock absorber is interposed between the base pile and the shock absorbing member absorbs a shock when the footing displaced so as to float from the foundation pile is restored. Further, a joint structure between a reinforced concrete foundation pile according to the present invention and a reinforced concrete footing supported by the foundation pile has a joint steel pipe integrally fixed to the bottom of the footing, The steel pipe has a constant cross-section, has a smooth outer peripheral surface, and is fixed so that its axial center extends in the vertical direction, and the footing concrete is placed therein, whereby the footing is formed. Forming a convex portion protruding downward from the bottom of the, the concrete of the foundation pile is placed so as to directly contact the outer peripheral surface of the lower part of the steel pipe for joining, surrounding the lower part, When a load that lifts the footing is applied, slipping occurs on the contact surface between the concrete of the foundation pile and the outer peripheral surface of the lower portion of the joining steel pipe, so that the footing is the base. A shock absorbing material is interposed between the upward surface of the head portion of the foundation pile and the downward surface of the bottom portion of the footing that faces the upward surface and is displaceable upward relative to the pile. The shock absorbing material absorbs the shock when the footing, which is mounted and is displaced so as to float from the foundation pile, returns to its original position.

Therefore, according to the joint structure of the present invention, the work of arranging the joint steel pipe and the impact absorbing material are added to the work normally required for constructing the reinforced concrete foundation pile and footing. Just by adding the work to be done, a joint structure that allows the footing to rise from the head of the foundation pile when a large overturning moment is applied to the building is obtained, and it is extremely easy to perform the additional work. You can Therefore, it is possible to obtain a joint structure between the foundation pile and the footing, which satisfies various requirements required for this kind of joint structure and has good workability.

[Brief description of drawings]

1A and 1B are perspective views showing specific examples of a joining steel pipe used for a joining structure between a foundation pile and a footing according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a joint structure between a foundation pile and a footing according to the first embodiment of the present invention.

FIG. 3 is a perspective view of a shock absorber retainer used in a joint structure between a foundation pile and a footing according to an embodiment of the present invention.

FIG. 4 is a cross-sectional view of a joint structure between a foundation pile and a footing according to the second embodiment of the present invention.

FIG. 5 is a cross-sectional view of a joint structure between a foundation pile and a footing according to a third embodiment of the present invention.

FIG. 6 is a sectional view of a joint structure between a foundation pile and a footing according to a fourth embodiment of the present invention.

[Explanation of symbols]

10 Steel pipe for joining 20 joint structure 22 Foundation pile 26 Footing 28 Main reinforcement of foundation pile 30 shock absorber 32, 34 Shock absorber retainer 40 joint structure 42,44 Shock absorber retainer 60 joint structure 80 joint structure 82 anchor 84 PC steel wire

Claims (8)

[Claims] 1. A joint structure between a reinforced concrete foundation pile and a reinforced concrete footing supported by the foundation pile, wherein a steel pipe for jointing is integrally fixed to the head of the foundation pile, The steel pipe for joining has a constant cross section, has a smooth outer peripheral surface, and is fixed so that its axial center extends in the vertical direction, and the concrete of the foundation pile is placed in it. , Forming a convex portion projecting upward from the head of the foundation pile, and placing the footing concrete so as to surround the upper portion of the joining steel pipe and directly contact the outer peripheral surface of the upper portion. When the load that lifts the footing is applied, slipping occurs on the contact surface between the concrete of the footing and the outer peripheral surface of the upper portion of the joining steel pipe, so that the footing is the foundation. And a bottom portion of the footing facing the upward surface of the head of the foundation pile defined at the tip of the convex portion or the periphery of the foot. A shock absorbing material is interposed between the shock absorbing material and the downward surface of the foundation pile, and the shock absorbing material absorbs a shock when the footing displaced so as to float from the foundation pile is restored. Bonding structure characterized by. 2. A joining structure between a reinforced concrete foundation pile and a reinforced concrete footing supported by the foundation pile, wherein a joining steel pipe is integrally fixed to the bottom of the footing, and The steel pipe has a constant cross-section, has a smooth outer peripheral surface, and is fixed so that its axial center extends in the vertical direction, and the footing concrete is placed therein, whereby the footing is formed. Forming a convex portion protruding downward from the bottom of the, the concrete of the foundation pile is placed so as to directly contact the outer peripheral surface of the lower portion of the steel pipe for joining, surrounding the lower portion, When a load that lifts the footing acts, the footing causes the slipping to occur in the contact surface between the concrete of the foundation pile and the outer peripheral surface of the lower portion of the joining steel pipe. The bottom face of the bottom of the footing defined at the tip of the convex portion or the periphery of the bottom pile and the bottom face of the foundation pile facing the bottom face. A shock absorbing material is interposed between the head and the upward surface of the head so that the shock absorbing material absorbs a shock when the footing displaced so as to float from the foundation pile is restored. , A joint structure characterized by the following. 3. The shock absorbing material, between a horizontal surface forming an end surface of the convex portion and a concrete surface facing the horizontal surface,
The joint structure according to claim 1 or 2, wherein the joint structure is provided on either or both of a horizontal surface around the convex portion and a concrete surface facing the horizontal surface. 4. The steel pipe for joining is made of a round steel pipe or a square steel pipe having a strength capable of functioning as a shear resistance mechanism for restraining a relative horizontal displacement of the footing with respect to the foundation pile. The joining structure according to any one of claims 1 to 3. 5. The joint structure according to claim 1, wherein the shock absorbing material is a granular material, a viscous material, or a rubber material. 6. The joint structure according to claim 1, further comprising a shock absorber retainer for holding the shock absorber at an interposed position. 7. The resistance force against lifting of the footing is increased by extending the main reinforcement of the foundation pile upward from the head of the foundation pile and connecting the foundation pile and the footing via the main reinforcement. The joint structure according to claim 1 or 2, wherein the joint structure is adjustable. 8. The resistance force against lifting of the footing can be adjusted by connecting the foundation pile and the footing through a PC steel wire and adjusting the magnitude of the prestress introduced into the PC steel wire. The joint structure according to claim 1 or 2, characterized in that.