JP5091343B1 - Seismic isolation structure - Google Patents

Abstract

[PROBLEMS] To prevent loss of function of a seismic isolation device attached to a pile head by restraining excessive rotation and horizontal deformation of the pile head relative to the ground in the conventional technology of the seismic isolation structure. Help maintain safety.
A base-isolated structure in which an upper structure is supported on the heads of a plurality of foundation piles 2 via a seismic isolation device 4, and a connecting beam or connection is provided between the pile heads of the foundation piles. Passive soil received by the bottom and sides of the pile 3 that has been dug down to the required depth of the ground without being provided with connecting members such as slabs. By using the ground reaction force that is the pressure, the pile head rotation due to the bending moment received during an earthquake and the horizontal deformation of the pile head due to the horizontal force are suppressed, and the loss of function of the seismic isolation device is prevented and it is always functioning normally. In addition to improving safety and saving materials, it is possible to save construction work and processes, maintain safety as a seismic isolation structure, reduce costs and shorten the construction period.
[Selection] Figure 1

Description

  The present invention relates to a seismic isolation structure in which an upper structure is supported via a seismic isolation device disposed on a foundation pile.

  A plurality of techniques are known for seismic isolation structures constructed through this type of seismic isolation device. As a first prior art according to the public knowledge, it is a base structure of a base-isolated structure in which an upper structure is supported on a foundation via a laminated rubber, and a foundation beam is provided at the bottom of the upper structure. In addition, the foundation is formed only from an independent pile or an independent direct foundation, and the foundation beam between the piles or the direct foundation is omitted, and the ground of the pile head of the independent pile used as the foundation This is a basic structure of a seismic isolation structure that allows the rotation without restricting the rotation (Japanese Patent Laid-Open No. 9-273162).

  According to the foundation structure of this seismic isolation structure, the foundation in the base isolation structure is composed only of independent piles or independent direct foundations, and the foundation beam connecting them is omitted. It can be simplified and can greatly contribute to the reduction of construction cost and the construction period. In particular, when a pile is employed, by adopting a structure that allows rotation of the pile head relative to the ground, there is an advantage that the pile head moment is eliminated and the maximum moment generated in the pile is reduced.

  In addition, as a second related art that is publicly known, a seismic isolation system comprising a building foundation that transmits and supports the load of the building body to the ground and a seismic isolation device that is fixed to the building foundation and supports the building body. The building foundation is configured to include a plurality of steel pipe piles penetrating into the ground and a connecting member that connects pile heads of the plurality of steel pipe piles, and the pile heads of the steel pipe piles The seismic isolation device is fixed on the part, and a base beam on the lowest floor of the building main body is directly fixed on the seismic isolation device (Japanese Patent Laid-Open No. 2006-104883).

  According to this seismic isolation building, the seismic isolation device is fixed on the pile head of the steel pipe pile, and the building main body is provided on this seismic isolation device. The amount of excavation can be reduced, and the construction period can be shortened and the cost can be reduced.

  Further, as a third related art that is publicly known, a pile head seismic isolation structure that supports the upper structure by seismic isolation using a seismic isolation device installed on the pile head, which is a flat structure for installing the seismic isolation device. The pile head capital is integrated with the pile head, and the pile head bending moment accompanying the occurrence of pile head rotation can be transmitted from the pile head to the pile head capital. By connecting the pile heads to each other, a flat bridging beam is provided to control the pile head rotation of each pile by bending back the pile bending moment transmitted from each pile head to each pile head capital. This is a pile head seismic isolation structure (Japanese Patent Laid-Open No. 2007-120232).

  According to this pile head seismic isolation structure, a flat pile head capital is provided on the pile head, a flat bridging beam is provided between the pile head capitals, and the pile head rotation is controlled by the flat bridging beam. Compared to the previous seismic isolation structure that unconditionally restrains the pile head rotation with a large cross-section and rigid foundation, the foundation as the lower structure can be greatly simplified, and the seismic isolation pit can also be made sufficiently shallow, The construction cost can be greatly reduced including the reduction of the amount of root cutting.

JP-A-9-273162 JP 2006-104883 A JP 2007-120232 A

  In the first prior art, a bottom plate is provided on a foundation pile, and a seismic isolation device that supports the upper structure is attached to the position corresponding to the pile head on the bottom pile. Because the head rotation is not constrained, it is not possible to control the excessive rotation and deformation amount of the pile head due to a huge earthquake, and the seismic isolation device is also deformed excessively, resulting in seismic isolation. The function is substantially lowered, and there is a problem that the seismic isolation device may be damaged together with the pile head.

  Moreover, in the said 2nd prior art, since it is the structure which connected the heads of the steel pipe piles with the connection member, it is recognized temporarily that it can suppress rotation and a deformation amount of a pile head, The foundation is a foundation slab formed to the required thickness by digging down the ground, and the foundation slab requires a lot of materials and is troublesome and costly. .

  Furthermore, in said 3rd prior art, while providing a pile head capital in a pile head, installing a flat connecting beam between adjacent pile head capitals, and connecting each pile head capital, each pile head The pile head moment transmitted from the pile head to the pile capital is bent back by the flat connecting beam to suppress the pile head rotation. For this reason, there is a problem that not only labor is required but also cost is increased.

  In recent years, with the spread of seismic isolation structures, various seismic isolation devices combining various functions have been developed. For example, the conventional friction isolation devices generally have a friction coefficient of about 0.1, but a sliding isolation device with a rotating mechanism having a friction coefficient of only 0.03 to 0.04 has been developed. It was. When this is used for a pile head seismic isolation structure, the pile should not receive any seismic force greater than the sliding friction force, and the horizontal force on the pile should be only about 3% of the support load. It becomes possible. In consideration of such circumstances, it is required to review the conventional pile head seismic isolation structure, propose a more rational structure, reduce costs and shorten the construction period.

  Therefore, in the prior art, the excessive rotation and horizontal deformation of the pile head relative to the ground is restrained to prevent the seismic isolation device from losing its function, thereby reducing the materials used and saving labor and processes. There is a problem to be solved in maintaining safety as a seismic structure, reducing costs and shortening the construction period.

The present invention is a seismic isolation structure in which an upper structure is supported via a seismic isolation device on the heads of a plurality of foundation piles arranged as specific means for solving the problems of the above-described conventional example, Without connecting members such as connecting beams and connecting slabs between the pile heads of the foundation pile, each pile head is dug down to the required depth of the ground, and a capital is provided, and a PC embedded in the sheath embedded in the capital A seismic isolation structure characterized in that a cable is inserted and alternately bypassed into an adjacent capital in an S-shape and sequentially inserted, and the inserted PC cable is fixed by filling the sheath with grout without being strained. It provides things.

In the present invention, before Symbol Capital and precast concrete structure, to the formation of the hanging wall or skirt to the bottom outer peripheral portion, and the plurality of foundation piles, connecting at least a portion of the pile head between a PC cable Is included as an additional requirement.

According to the seismic isolation structure according to the present invention, the capital of the pile head can be obtained by digging down to the required depth of the ground on each pile head of the plurality of foundation piles and integrally forming the capital. However, the ground reaction force, which is the passive earth pressure received at the bottom and sides, can be used to suppress the rotation of the pile head due to the bending moment received during an earthquake and the horizontal deformation of the pile head due to the horizontal force. To prevent loss of function of the seismic isolation device, improve its safety by always functioning normally, reduce the materials used, save labor in construction work and processes, and maintain safety as a seismic isolation structure In addition, there is an excellent effect that the cost can be reduced and the construction period can be shortened.
In addition, by connecting the pile heads by adding a PC cable for connection to the capital attached to the pile head, the pile head deformation control effect for the entire foundation pile group and the deformation restoration function after the earthquake And the cost can be greatly reduced as compared with a conventional concrete connecting member.

It is the side sectional view showing roughly the principal part of the seismic isolation structure concerning a 1st embodiment of the present invention. It is a top view which shows the foundation pile part of the seismic isolation structure which concerns on the same embodiment. It is an image figure which shows the rotation deformation | transformation of the pile head by the earthquake of a seismic isolation structure, Comprising: FIG. (A) is suppression of rotation of a pile head and horizontal deformation in the base isolation structure which concerns on the said 1st Embodiment. (B) is explanatory drawing which showed rotation and horizontal deformation | transformation of the pile head without a capital. It is side sectional drawing which showed schematically the principal part of the seismic isolation structure which concerns on the 2nd Embodiment of this invention. It is a top view which shows the foundation pile part of the seismic isolation structure which concerns on the same embodiment. It is a figure which shows the concept of the acting force which the foundation pile part of a base isolation structure receives in an embodiment in the same embodiment, Comprising: A figure (a) is a conceptual diagram of a pile head rotation stop, A figure (b) is a pile head (C) is a conceptual diagram of ground side flow prevention. It is side sectional drawing which showed schematically the principal part of the seismic isolation structure which concerns on the 3rd Embodiment of this invention. It is a top view which shows the foundation pile part of the seismic isolation structure which concerns on the same embodiment. It is side sectional drawing which showed schematically the principal part of the seismic isolation structure which concerns on the 4th Embodiment of this invention. It is a top view which shows the foundation pile part of the seismic isolation structure which concerns on the same embodiment. It is a top view which shows the whole foundation pile part of an example of the seismic isolation structure which concerns on the same embodiment. It is explanatory drawing which showed the condition of the tension | tensile_strength applied to PC cable which comprises a part of seismic isolation structure concerning the embodiment.

  The present invention will be described in detail based on the illustrated embodiment. First, FIG. 1 and FIG. 2 show the main part of the seismic isolation structure according to the first embodiment of the present invention, and an earth drill that is formed by orderly driving the appropriate ground 1 at a necessary interval. The capital 3 is integrally formed at the upper end of the foundation pile 2 such as a pile, that is, the pile head 2a.

  In this case, the formation of the capital 3 with respect to the pile head 2a is, in essence, formed integrally on the spot, and the ground 1 around the pile head 2a in the foundation pile 2 is dug down to the required depth and width. A form corresponding to the size and shape of the capital 3 to be formed is made, and a reinforcing bar for the capital of the pile head 2a is placed in the form and the capital 3 is integrated with the pile head 2a. To form. And the seismic isolation device 4 is attached to the upper surface of the pile head 2a thru | or the capital 3, and the footing 5 is attached to this seismic isolation device 4, The pillar 7 of the upper structure 6, the lower large beam 8, and the floor via this footing 5 A slab 9 is constructed. Of course, the footing 5 is also a member included in the upper structure 6. A discarded concrete layer 1a is provided on the upper surface of the ground 1, and a reinforcing steel pipe 2b is provided on the pile head.

Regarding the size and shape (width and height) of the capital 3 to be formed, the bottom surface necessary for the reaction force that restrains or suppresses the bending moment generated during the rotation of the pile head and the horizontal deformation caused by the horizontal force during an earthquake. And the area of the side.
In short, as shown in FIGS. 3 (a) and 3 (b), the case where capital is formed on the pile head and the case where capital is not formed are considered. When capital is not formed as shown in FIG. 3 (b) The seismic isolation device 4 attached to the pile head with a large rotation of the pile head 2a is greatly deformed not only in the horizontal direction but also in the vertical direction. The function of the device 4 may be damaged.

On the other hand, when the capital 3 of the required size (bottom area and side thickness) is attached as shown in Fig. (A), the size depends on the seismic isolation device used and the condition of the ground. Although it is different, the reaction force h ₁ for suppressing the rotation of the pile head and the reaction force h ₂ for restraining or suppressing the horizontal deformation are substantially maintained between the ground 1.

  In this way, the capital 3 having the required size and thickness is integrally formed on the pile head 2a of the foundation pile 2, thereby suppressing bending moment and horizontal deformation during rotation of the pile head 2a due to an earthquake or the like. Thus, it is possible to construct a seismic isolation structure that can be fully exerted without damaging the function of the seismic isolation device 4. If necessary, the jack 10 can be replaced when the seismic isolation device 4 is replaced. In order to sufficiently support the reaction force, the capital 3 can be thickened and a thick reinforcing bar or steel frame can be put inside to increase the strength.

  4-5 shows the principal part of the seismic isolation structure which concerns on 2nd Embodiment, and attaches | subjects and demonstrates the same code | symbol to the same part as the said 1st Embodiment. In this embodiment, the capital 23 is formed of precast concrete, and the capital 23 is inserted and fixed to the pile head 2 a of the foundation pile 2. In this case, a stopper 13 for positioning the insertion position of the capital 23 to be inserted is provided, and the other side of the capital 23 to be inserted is disposed on the inner peripheral surface of the hole 12 at the center. A shear cotter 14 is formed as a recess. After the capital 23 is inserted into the pile head 2a, the joint non-shrink mortar 15 is injected into the joint 11 formed between the steel pipe 2b of the pile head and the hole 12. By making it fill, the capital 23 is fixed to the pile head 2a. In this way, by forming the capital 23 with precast concrete, it is possible to save time and labor for the formwork formation and the bar arrangement work at the site, so that the construction period can be shortened.

  Moreover, in the capital 23 made from precast concrete, the hanging wall or the skirt part 23a is formed along the outer peripheral part on the bottom surface side, and the inside holds the ground 1 by the formation of the hanging wall or the skirt part 23a. Or it will be in a state and the area of the ground reaction force which is a passive earth pressure can be increased substantially. Then, as in the first embodiment, the seismic isolation device 4 is attached to the pile head 2a, and the column 7, the lower beam 8 and the floor slab 9 of the upper structure 6 including the footing 5 are attached to the seismic isolation device 4. Etc. are built.

In the seismic isolation structure according to the second embodiment formed in this way, as shown in the conceptual diagram of the pile head rotation stop in FIG. 6A, Mt acting on the pile head 2a when an earthquake occurs. = pile during rotation bending moment, a bending moment due to the reaction force h ₁ of the rotation restraint of the MR = Capital. Moreover, as shown in the conceptual diagram of the pile head horizontal resistance force in FIG. 6B, EX = horizontal force acting on the pile head during an earthquake, V = passive earth pressure by capital (= h ₂ · A), A = A reaction force h _{2 that} is a capital horizontal resistance area and restrains or suppresses horizontal deformation is substantially maintained between the ground 1 and the ground. Furthermore, as shown in the ground side flow prevention conceptual diagram of FIG. 6 (c), the side wall of the ground 1 during liquefaction can be prevented by the hanging wall or the skirt portion 23a provided in the capital 23, it is possible to secure a restraint effect by the reaction force h ₁ and h ₂ of the ground 1 for rotation or horizontal deformation of the pile head 2a.

  Next, FIGS. 7-8 shows the principal part of the seismic isolation structure which concerns on 3rd Embodiment, and since it improved further the said 2nd Embodiment, 2nd Embodiment The same reference numerals are given to the same parts as those in the embodiment, and the description thereof is omitted. In this embodiment, the capital 23 has the same structure as that of the second embodiment, and the pile head 2a side to which the capital 23 is attached is improved and the attached state is made stronger. is there. That is, a plurality of steel brackets 16 are provided on the outer peripheral surface of the pile head 2a at the same level, and the bottom surface of the capital 23 is brought into contact with the bracket 16 so as to form a recess. In combination with this, the attachment of the capital 23 to the pile head 2a becomes stronger and more stable, and is suitable for a high-rise seismic isolation building. In particular, by providing the steel bracket 16, the capital 23 can sufficiently support the reaction force of the jack 10 when the seismic isolation device 4 is replaced.

  Furthermore, FIGS. 9-12 shows the principal part of the seismic isolation structure which concerns on 4th Embodiment, Since the said 2nd and 3rd embodiment was improved further, the said 1st The same parts as those of the second and third embodiments are denoted by the same reference numerals and the description thereof is omitted. In the fourth embodiment, a precast concrete capital 33 having a pair of sheaths 17 arranged in advance is prepared, and this is intended to strengthen the building, for example, at least the building. Is attached to the pile head 2a of the foundation pile 2 provided so as to cross the periphery or the center of the pile. For other positions, the capital 23 according to the second or third embodiment may be used. In addition, it is good also as a capital formed by on-site strike.

  The arrangement of the pair of sheaths 17 with respect to the capital 33 of the fourth embodiment is such that, as shown in FIGS. 9 and 10, the central hole 12 into which the pile head 2 a provided in the capital 33 is inserted is provided. Each of the sheaths 17 is arranged so as to be curved so as to surround from both sides, and a grout hose 18 is provided on each end of each sheath 17, and one of the grout hoses 18 is used as an inlet and the other as an outlet. . And finally, the PC cable 19 which carried out the antirust process is inserted in each arrange | positioned sheath 17, and a temporary fixing is made. In this case, the adjacent pile heads 2 a are inserted and connected so as to be connected in series by the PC cable 19. In addition, although not specifically mentioned as an Example, about the capital 43 used for a corner part, what a pair of each sheath 17 was arrange | positioned by cross shape is used.

  The capital 33 according to the fourth embodiment formed in this way is, for example, as shown in FIG. 11, a foundation pile at a position where it is desired to strengthen as a building, in particular, at a position crossing the peripheral edge and the center. The PC cable 19 is sequentially inserted into each sheath 17 of the adjacent capital 33 after the capital 33 is attached after being oriented once. As a result, both PC cables 19 alternately bypass the pile heads 2a in an S-shape and connect adjacent pile heads 2a in series, and do not give special tension to the inserted PC cables 19. In this state, the grout is injected and solidified and fixed by the adhesion force, and the adjacent pile heads 2 a are temporarily connected by the PC cable 19.

  When the pile heads 2a are connected in series with each other with the PC cable 19, for example, when a strong earthquake is applied, the tensile force T due to horizontal movement in the X-axis direction is applied to the PC cable 19 as shown in FIG. Even if it occurs, the PC cable 19 resists with an average adhesion stress τ due to grout in the curved sheath 17 and resists by the deformation restraining force Ry toward the center of the pile head 2a in the Y-axis direction. To do.

Thus, by adding the connecting PC cable 19 to the capital 33 attached to the pile head 2a and connecting the pile heads to each other, the pile head deformation suppressing effect on the entire foundation pile group and the deformation after the earthquake The restoration function can be improved.
In addition, as the rust-proof treated PC cable 19 used, for example, it is a stranded wire made of PC steel and coated with a rust-proof coating on the outer peripheral surface of each of the core wire and the side wire, or after galvanizing, The ones that have been subjected to are used. In short, one or a plurality of strands of PC steel processed so as not to rust even when used for a long time are used.

Moreover, in this invention, although the usage example of the earth drill pile was shown as a foundation pile in the Example, it is not limited to this, A spot cast concrete pile, a steel pipe concrete pile, etc. may be sufficient. In short, various changes can be made to each configuration shown in the above-described embodiment without departing from the gist of the present invention, and the configuration is not limited to each configuration in the above-described embodiment.
If the seismic isolation device has a small friction coefficient as described above, the horizontal force on the pile is reduced, and the capital of the pile head can be reduced. Since it becomes a suitable thing, it is preferable to use what makes a friction coefficient 0.07 or less.
Although illustration is omitted, when the horizontal deformation of the pile head is small on good ground, the pile head capital is installed on the ground and the pile head rotation is suppressed by passive earth pressure on the bottom of the capital. And it is good also as a structure which attaches the PC cable for connection to a pile head, and connects pile heads. As a result, the excavation work of the ground and the labor of backfilling the remaining soil can be reduced, and the cost can be greatly reduced as compared with a conventional connecting member made of concrete.

  The base isolation structure according to the present invention is a base isolation structure in which an upper structure is supported by a plurality of foundation pile heads via a base isolation device, and between the pile heads of the foundation pile. Capital is attached to each pile head in response to the reaction force of the ground against rotation and horizontal deformation, without attaching extra connecting members such as tie beams and connecting slabs. Since the capital can enhance the restraint effect on the rotation and horizontal deformation of the pile head, it can protect the seismic isolation function by suppressing excessive deformation of the seismic isolation device. Regardless of, it can be widely used as a seismic isolation structure.

DESCRIPTION OF SYMBOLS 1 Ground 1a Abandoned concrete layer 2 Foundation pile 2a Pile head 2b Steel pipe 3, 23, 33, 43 Capital 3a Hanging part or skirt part 4 Seismic isolation device 5 Footing 6 Upper structure 7 Pillar 8 Lower girder 9 Floor slab 10 Jack 11 Joint
12 hole 13 stopper for positioning 14 shear cotter 15 mortar 16 bracket 17 sheath 18 grout hose 19 PC cable

Claims (3)

It is a seismic isolation structure in which the upper structure is supported via a seismic isolation device on the heads of the multiple foundation piles,
Without providing a connecting member such as a connecting beam or a connecting slab between the pile heads of the foundation pile, each pile head is dug down to the required depth of the ground, and capital is provided,
A PC cable is inserted through the sheath embedded in the capital, and it is alternately inserted in the adjacent capital by alternately detouring in an S-shape,
A seismic isolation structure characterized in that the inserted PC cable is fixed by filling the sheath with grout without being strained . The base-isolated structure according to claim 1, wherein the capital is precast concrete, and a hanging wall or a skirt portion is formed on an outer peripheral portion of the bottom surface. In the plurality of foundation piles, at least some of the pile heads are connected with a PC cable.
The seismic isolation structure according to claim 1 or 2.

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