JP3102548B2 - Seismic isolation structure of pile - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a seismic isolation structure for a pile supporting a structure.

[0002]

2. Description of the Related Art A pile foundation is one of the types of foundation adopted when a high-quality support layer is deep underground. By constructing an upper structure on a pile driven into the support layer, The weight of the structure can be stably supported by the support layer.

[0003] Such a pile tends to have a relatively weak point against horizontal force due to its structural characteristics. During an earthquake, a large horizontal force or bending moment acts on the pile head from the upper structure. A situation such as destruction directly leads to the collapse of the superstructure. Therefore, it is necessary to study enough to prevent the pile from breaking.

[0004] Various seismic isolation structures have been proposed as measures to prevent damage to piles. As an effective means, there is a plan to provide a laminated rubber between the superstructure and the pile head.
According to this method, the level of the seismic motion input to the upper structure is reduced due to the prolongation of the period by the laminated rubber, and the horizontal force and bending moment acting on the pile head are also reduced.

[0005]

However, arranging the laminated rubber on the pile head means, of course, that a clearance large enough to allow horizontal displacement of the upper structure must be provided on the side of the upper structure. This means that the upper structure below the ground surface must be double-walled.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and provides a pile seismic isolation structure capable of reducing horizontal displacement of an upper structure and preventing damage to the pile. With the goal.

[0007]

In order to achieve the above object, a seismic isolation structure for a pile according to the present invention is, as described in claim 1, an upper structure and a head of the pile for supporting the upper structure. And an insulating mechanism using a slide bearing, a ball bearing, or the like, is disposed between them, and a pair of tension members fixed in the ground are fixed to the upper structure using a predetermined fixing member.

Further, in the seismic isolation structure for a pile according to the present invention, a predetermined damper member is interposed between the fixing member and the upper structure, and the tension of the tension member is applied via the damper member. The power is transmitted between the fixing member and the upper structure.

In the seismic isolation structure for a pile according to the present invention, the damper member is formed of a superelastic material.

The seismic isolation structure of the pile according to the present invention is different from the conventional seismic isolation structure in which both the superstructure and the pile are seismically isolated, and mainly considers seismic isolation of the pile. . That is, in the seismic isolation structure of a pile according to the present invention, an insulation mechanism using a sliding bearing, a ball bearing, or the like is provided between the upper structure and the head of the pile supporting the upper structure, and A pair of tension members fixed inside are fixed to the upper structure using a predetermined fixing member, and in the event of an earthquake, the tension members prevent horizontal movement and fall of the upper structure, and Horizontal forces and bending moments from the structure are blocked by the insulation mechanism and do not act on the pile head. Since the energy of the seismic motion is input to the upper structure via the tensile member, the upper structure itself is constructed based on a predetermined seismic design standard.

Here, when a damper member is interposed between the fixing member and the upper structure, the vibration energy of the upper structure is absorbed by the damper member, and the upper structure can be made to have a certain degree of seismic isolation. Become.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a seismic isolation structure for a pile according to the present invention will be described below with reference to the accompanying drawings.

FIG. 1A is an overall view showing a seismic isolation structure of a pile according to the present embodiment. As can be seen from the figure, in the seismic isolation structure of a pile according to the present embodiment, a sliding bearing 3 as an insulating mechanism is arranged between an upper structure 1 and a head of a pile 2 supporting the upper structure 1. The upper structure 1 is fixed in the ground 5 with a pair of anchors 4 and 4 crossing each other.

The sliding bearing 3 is made of a material having a low coefficient of friction, for example, Teflon material, so that the horizontal force and bending moment from the upper structure 1 do not act on the head of the pile 2 as much as possible during an earthquake. And foundation slab 6 of superstructure 1
And is provided on the lower surface of the device.

On the ground side, the anchor 4 is fixed using a grout material in a hole formed by drilling one end of a tensile member 7 such as a PC steel wire to a solid layer (not shown). As shown in FIG. 1 (b), the tension member 7 is passed through the through hole 8 of the base slab 6, and the other end thereof is
It is inserted into holes of the damper member 10 and the anchor head 11 serving as a fixing member, and is fixed to the anchor head 11 by a wedge (not shown). It should be noted that the tensile material 7
Is covered with a cap 12 and grease is sealed therein.

The damper member 10 is formed of a material called a superelastic material, for example, in an annular shape as shown in FIG. 1 (c). Is transmitted through the damper member 10. As the superelastic material forming the damper member 10, for example, a Ti—Ni alloy, a Cu—Au—Zn alloy, or the like can be used.

In the seismic isolation structure for piles according to the present embodiment, the upper structure 1
This prevents horizontal movement and fall of
The horizontal force and the bending moment are blocked by the slide bearing 3 and do not act on the head of the pile 2. Also, the damper member 1
By 0, the vibration energy of the upper structure 1 is absorbed,
The upper structure 1 is also isolated to some extent.

FIG. 2 shows a stress-strain curve of the damper member 10 formed of a superelastic material, and the seismic energy absorption mechanism will be described using such a graph.

First, as shown in FIG. 2 (a), the tension P of the tension member 7 acts on the damper member 10 in a normal state (the position shown by a black circle), and when a relatively small earthquake comes, Moves on a curve centered on the position of the black circle, but the moving range is limited to the elastic range, and energy is not absorbed.

On the other hand, during an earthquake, the tension P
And a horizontal stress component from the upper structure 1 in accordance with the inclination angle of the anchor 4 acts thereon, and energy absorption is performed while drawing a history unique to superelasticity, as shown in FIG. .

As described above, according to the seismic isolation structure of the pile according to the present embodiment, since the sliding bearing is provided between the upper structure and the pile, the horizontal force from the upper structure during an earthquake can be reduced. The bending moment does not act on the pile, preventing damage to the pile and preventing the horizontal movement, lifting or falling of the upper structure by anchoring the upper structure to the ground using anchors be able to.

Therefore, the pile can be seismically isolated without forming a double wall on the side of the upper structure lower than the ground surface.

Further, since a damper member is interposed between the fixing member and the upper structure to absorb the vibration energy of the upper structure with the damper member, seismic isolation of the upper structure is achieved to some extent. It is possible to do.

In this embodiment, the damper member is formed of a superelastic material. Alternatively, as shown in FIG. 3, a damper member 21 formed of a high damping rubber may be used.

Further, in this embodiment, the pair of anchors 4, 4 are arranged crosswise, but they may be arranged as shown in FIG.

In this embodiment, a sliding bearing is used as the insulating mechanism, but a bearing or the like may be used instead.

Further, in this embodiment, the damper member 10 is interposed between the anchor head 11 of the anchor 4 and the support plate 9, but as shown in FIG. 5, an anchor 31 in which the damper member is omitted is used. You may.

According to such a configuration, the horizontal force and the bending moment from the upper structure 1 do not act on the pile 2 at the time of the earthquake, so that the pile 2 can be prevented from being damaged and the horizontal movement of the upper structure 1 can be prevented. And lifting or falling can be prevented.

Therefore, as in the above-described embodiment, the pile 2 can be seismically isolated without forming a double wall on the side of the upper structure 1 lower than the ground surface. Since the energy of the seismic motion is input to the upper structure 1 via the tensile member 7, the upper structure itself is constructed based on a predetermined seismic design standard.

[0030]

As described above, the seismic isolation structure for a pile according to the present invention provides an insulating structure using a sliding bearing, a ball bearing, or the like between the superstructure and the head of the pile supporting the superstructure. A mechanism is arranged, and a pair of tension members fixed in the ground are fixed to the upper structure using a predetermined fixing member, so that the horizontal displacement of the upper structure is reduced and the pile is also damaged. Can be prevented.

[0031]

[Brief description of the drawings]

FIG. 1 is a view showing a seismic isolation structure of a pile according to the present embodiment, (a) is an overall side view, (b) is a detailed view showing a fixing structure on an upper structure side, and (c) is a damper. The perspective view of a member etc.

FIG. 2 is a graph showing a stress-strain curve of a damper member, wherein (a) shows the stress-strain level generated during normal times and small earthquakes, and (b) shows the stress-strain levels during a large earthquake. The resulting stress-strain level is added.

FIG. 3 is a perspective view showing a modified example of a damper member.

FIG. 4 is an overall side view showing a seismic isolation structure of a pile according to a modification.

FIG. 5 is an overall side view showing a seismic isolation structure of a pile according to a modification.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Upper structure 2 Pile 3 Sliding bearing (insulation mechanism) 4, 31 Anchor 5 Ground 7 PC steel wire (tensile material) 10 Damper member 11 Anchor head (fixing member) 21 Damper member

Continuation of the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) E02D 27/12 E02D 27/34 E04H 9/02 311 E04H 9/02 331

Claims (3)

(57) [Claims] An insulating mechanism using a sliding bearing, a ball bearing, or the like is provided between an upper structure and a head of a pile supporting the upper structure, and a pair of tension members fixed in the ground. A seismic isolation structure for piles, wherein a material is fixed to the upper structure using a predetermined fixing member. 2. A predetermined damper member is interposed between the fixing member and the upper structure, and a tension of the tension member is applied between the fixing member and the upper structure via the damper member. The seismic isolation structure of a pile according to claim 1, wherein the pile is transmitted. 3. The seismic isolation structure of a pile according to claim 2, wherein said damper member is formed of a superelastic material.