Base isolation structure of building

Abstract

To protect an artificial ground.SOLUTION: A base isolation structure of a building includes: a steel pipe pile 1 which has a pile body 11 and a pile head plate 122 provided on the upper end of the pile body 11, and has a pile body head part 11H and a pile head plate 122 above a ground surface GL by embedding a pile body main part 11M in the ground G; a seismic isolator 2 which is mounted between the pile head plate 122 and a footing beam 3; pile head concrete 4 which is provided into a cylindrical shape along the outer peripheral surface of the pile body head part 11H from the ground surface GL; and an artificial ground 5 which is provided on the ground surface GL and surrounds the outer periphery of the pile head concrete 4. The pile head concrete 4 suppresses bending of the pile body head part 11H when a load F is applied to the pile head plate 122 through the seismic isolator 2, and the artificial ground 5 surrounds at least the lower part of the pile head concrete 4, with the edge cut with respect to the pile head concrete 4.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a seismic isolation structure for a building. [Background technology]

[0002] Seismic isolation structures equipped with a seismic isolation device between steel pipe piles and a building foundation are known. For example, Patent Document 1 describes a seismic isolation structure equipped with a seismic isolation device between steel pipe piles and a flat slab foundation. The seismic isolation device is a device that suppresses horizontal movement of a building when an earthquake occurs and reduces the external force that the building receives. In the seismic isolation structure of Patent Document 1, the main part of the steel pipe pile is buried in the ground, so that the pile body head and pile cap plate are located above the ground surface. The lower part of the seismic isolation device is attached to the pile cap plate, and the upper part of the seismic isolation device is attached to a flat slab foundation. Furthermore, the pile body head is fixed by artificial ground (e.g., a concrete slab) installed on the ground surface.

[0003] In the seismic isolation device of Patent Document 1, the lower and upper parts of the device are configured to be freely movable within a predetermined range in the horizontal direction. When an earthquake causes the ground to move horizontally, the lower part of the device moves together with the steel pipe piles, but the upper part of the device, which receives the load from the building, moves less than the lower part of the device due to inertial force. Therefore, when an earthquake occurs, the positions of the lower and upper parts of the seismic isolation device will shift horizontally, and the magnitude of the shift will increase in proportion to the amount of horizontal movement of the ground. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 3756158 Summary of the Invention [Problem to be solved by the invention]

[0005] In the seismic isolation device of Patent Document 1, if the lower and upper sections are misaligned, a load is applied in a direction that bends the head of the steel pipe pile. The heavier the building or other structure is and the greater the misalignment between the lower and upper sections, the greater the load in the bending direction. If the load becomes excessively large, the head of the pile may bend or the artificial ground may be damaged by the head of the pile. The present invention has been made in view of the above circumstances, and its object is to protect the artificial ground. [Means for solving the problem]

[0006] In order to solve the above problems, the seismic isolation structure for a building of the present invention comprises a steel pipe pile having a pile body and a pile head plate attached to the upper end of the pile body, and having the main part of the pile body buried in the ground so that the pile body head and the pile head plate are positioned above the ground surface; a seismic isolation device attached between the pile head plate and the building foundation; a pile head concrete arranged in a cylindrical shape from the ground surface along the outer surface of the pile body head; and artificial ground arranged on the ground surface and surrounding the outer periphery of the pile head concrete, wherein the pile head concrete suppresses bending of the pile body head when a load is applied to the pile head plate through the seismic isolation device, and the artificial ground surrounds at least the lower part of the pile head concrete and is edged off from the pile head concrete. [Effects of the Invention]

[0007] According to the present invention, the artificial ground can be protected. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram showing the seismic isolation structure of a building. [Figure 2] This is an enlarged cross-sectional view of the head of a steel pipe pile and a seismic isolation device. [Figure 3] FIG. 2 is a partially enlarged cross-sectional view showing the operating state of the seismic isolation device. [Figure 4] FIG. 10 is a diagram showing the positions of the steel pipe piles and the oil dampers. [Figure 5] FIG. [Figure 6] FIG. 1 is a perspective view of a pile cap member with an L-shaped anchor bolt attached. [Figure 7] FIG. 1 is a plan view of the pile head concrete and pile head plate. [Figure 8] FIG. 1 is a perspective view of a pile head concrete and a pile head plate. [Figure 9] This is a plan view of the pile cap plate and the lower seismic isolation plate. [Figure 10] FIG. 1 is a perspective view of a pile cap plate and a lower seismic isolation plate. [Figure 11] FIG. 2 is a partially cutaway cross-sectional view illustrating an oil damper. [Figure 12] FIG. 10 is a diagram showing the state in which the main part of the pile body has penetrated into the ground. [Figure 13] FIG. 10 is a view showing the head of the pile body with the pile head member attached. [Figure 14] FIG. 10 is a diagram showing the installation state of the cylindrical pipe. [Figure 15] FIG. 10 is a diagram showing the state in which reinforcement is arranged at the location where the artificial ground is to be formed. [Figure 16] FIG. 1 is a diagram showing concrete pouring work. [Figure 17] FIG. 10 is a diagram showing the state in which the lower seismic isolation plate is attached. [Figure 18] 10A and 10B are diagrams showing the installation process of the upper seismic isolation plate. [Figure 19] FIG. 10 is a diagram showing a first modified example of a seismic isolation structure. [Figure 20] FIG. 10 is a diagram showing a second modified example of the seismic isolation structure. [Figure 21] FIG. 10 is a diagram showing a third modified example of the seismic isolation structure. [Figure 22] FIG. 10 is a diagram showing a fourth modified example of the seismic isolation structure. [Figure 23] 10(a) and 10(b) are diagrams showing modified examples of the pile head member. [Figure 24](a) is a perspective view of an upper pile equipped with a pile head plate, and (b) is a perspective view of an upper pile with a bolt insertion hole and a concrete viewing hole drilled in the pile head plate. DETAILED DESCRIPTION OF THE INVENTION

[0009] <Outline of the building's seismic isolation structure> First, an overview of the seismic isolation structure for buildings will be described. However, unless otherwise specified, the components, types, combinations, shapes, and relative arrangements described in this embodiment are merely illustrative examples and do not intend to limit the scope of this invention. For example, the configurations described in multiple modified examples may be combined and applied to the configuration of this embodiment. FIG. 1 is a diagram showing the seismic isolation structure of building BD, FIG. 2 is a partially enlarged cross-sectional view of the pile head of steel pipe pile 1 and seismic isolation device 2, and FIG. 3 is a partially enlarged cross-sectional view showing the operating state of seismic isolation device 2.

[0010] As shown in Figure 1, the steel pipe pile 1 has a pile body 11 (pile shaft) and a pile cap plate 122 attached to the upper end of the pile body 11, and the pile body main part 11M is penetrated (buried) into the ground G, so that the pile body head 11H and the pile cap plate 122 are located above the ground surface GL. A steel-frame foundation beam 3 (building foundation) is provided at the bottom of the building BD, and a seismic isolation device 2 is attached between the foundation beam 3 and the pile cap plate 122. As shown in FIG. 2, a cylindrical concrete pile head 4 is provided from the ground surface GL along the outer circumferential surface of the pile main body head 11H.

[0011] As shown in Figures 1 to 3, an artificial ground 5 is provided on the ground surface GL. The artificial ground 5 is made of, for example, reinforced concrete, and is provided so as to surround at least the lower part of the concrete pile cap 4. The artificial ground 5 is provided to determine the horizontal position of the steel pipe pile 1 and to support oil dampers 6 which determine the position of the building BD. A resin cylindrical pipe 41 (a resin hollow member) is interposed between the artificial ground 5 and the outer surface of the pile head concrete 4, and the artificial ground 5 and the pile head concrete 4 are separated from each other.

[0012] As shown in Figure 3, when an earthquake occurs, when the ground G and the building BD move relative to each other via the seismic isolation device 2, the position of the lower seismic isolation plate 21 and the upper seismic isolation plate 22 provided on the seismic isolation device 2 shifts, and a load (external force) is applied to the pile head plate 122 via the slider 23 as shown by the arrow with symbol F. The load F acts in a direction that bends the pile head 11H of the steel pipe pile 1. The concrete pile head 4 receives a reaction force from the ground G and protects the pile head 11H from bending. At this time, because the cylindrical pipe 41 separates the edge between the concrete pile head 4 and the artificial ground 5, the artificial ground 5 is less susceptible to the effect of the load F that the pile head 11H receives, and is protected from damage such as cracks. In this way, according to the seismic isolation structure of the building BD according to this embodiment, the pile main body head portion 11H and the artificial ground 5 can be protected.

[0013] <Details of the seismic isolation structure of Building BD> The seismic isolation structure of building BD will be described in detail below. Figure 4 is a diagram showing the positions of steel pipe piles 1 and oil dampers 6. In the example shown in Figures 1 and 4, 16 steel pipe piles 1 are arranged at intervals in the front-to-back and left-to-right directions, but the number and arrangement of the steel pipe piles 1 are just examples and are not limited to this example.

[0014] As shown in Figure 1, a tip cutting edge 13 is fixed by welding or the like to the lower end of a pile body 11 provided on a steel pipe pile 1. The tip cutting edge 13 is fixed to the tip of the pile body 11 at a predetermined inclination, and generates a propulsive force when the pile body 11 is penetrated into the ground G or when the pile body 11 is extracted from the ground G. For example, by bringing the tip cutting edge 13 into contact with the ground surface GL and rotating the pile body 11 in the forward direction around its axis, the pile body 11 can be penetrated into the ground G. In addition, by rotating the pile body 11 buried in the ground G in the direction opposite to the forward direction around its axis, the pile body 11 can be extracted from the ground G.

[0015] The thickness of the pile body 11 is determined according to the maximum construction depth, and is set within the range of, for example, 100 mm to 400 mm, but is not limited to this range. For example, the maximum construction depth is approximately 10 m when the thickness is 100 mm, and approximately 50 m when the thickness is 400 mm. The steel pipe pile 1 shown in Figure 1 comprises a lower pile 111 equipped with a tip cutting edge 13, an intermediate pile 112 connected to the upper end of the lower pile 111, and an upper pile 113 connected to the upper end of the intermediate pile 112, and a pile head member 12 (see Figure 5, etc.) equipped with a pile head plate 122 is connected to the upper end of the upper pile 113. The lower pile 111, the intermediate pile 112, the upper pile 113, and the pile cap member 12 can be connected by welding, for example, but other connecting means such as bolt fastening may also be used. 2, the pile main body head 11H and the pile head plate 122 are located above the ground surface GL. For example, the height from the ground surface GL to the top end 122a (upper surface) of the pile head plate 122 is 200 mm to 600 mm.

[0016] FIG. 5 is a perspective view of the pile head member 12, and FIG. 6 is a perspective view of the pile head member 12 to which an L-shaped anchor bolt 124 is attached. The pile head member 12 shown in FIG. 5 includes a cylindrical portion 121 connected to the upper end of the upper pile 113 , and a pile head plate 122 provided at the upper end of the cylindrical portion 121 . The tubular portion 121 is a cylindrical member that is connected to the upper end of the upper pile 113 and forms part of the pile main body 11 (pile main body head portion 11H). A plurality of anchoring bolts 123 are attached to the outer circumferential surface of the tubular portion 121, facing radially outward.

[0017] The anchoring bolts 123 are provided for the purpose of enhancing the unity between the pile head concrete 4 and the pile head member 12. In the illustrated example, four anchoring bolts 123 are provided at 90-degree intervals along the circumferential direction at the mid-height of the tubular portion 121, but the number of anchoring bolts 123 and their installation intervals can be determined appropriately. The pile cap plate 122 is a disk-shaped steel plate with a diameter of, for example, 400 mm to 800 mm and a thickness of, for example, 20 mm to 50 mm, but is not limited to these numerical ranges. Furthermore, the shape in plan view is not limited to a disk shape and may be a rectangle.

[0018] A bolt insertion hole 122b and a concrete viewing hole 122c are provided in the pile head plate 122. The bolt insertion hole 122b is a hole for inserting a bolt (for example, an L-shaped anchor bolt 124) for attaching the seismic isolation device 2, and is provided so as to penetrate the pile head plate 122 in the thickness direction. As shown in Fig. 6, in this embodiment, an L-shaped anchor bolt 124 is used as a mounting bolt for the seismic isolation device 2. In the example shown in Fig. 6, the L-shaped anchor bolt 124 is temporarily fixed to the pile cap plate 122 by tightening a nut 124a onto the upper end of the L-shaped anchor bolt 124.

[0019] The concrete viewing hole 122c is provided for the purpose of visually checking the fluidized concrete (concrete before hardening) when pouring the pile head concrete 4. For this reason, the concrete viewing hole 122c is provided so as to penetrate the pile head plate 122 in the thickness direction. In this embodiment, the concrete viewing hole 122c is provided at a position radially outward of the cylindrical portion 121 (pile main body 11) and close to the cylindrical portion 121. The reason is that the upper end of the cylindrical portion 121 is covered by the pile head plate 122, making it difficult to see the state of concrete filling. By providing the concrete viewing hole 122c, the state of concrete filling can be visually confirmed during pouring. In addition, since the concrete viewing hole 122c penetrates the thickness of the pile head plate 122, air can be discharged from the pouring space (the inner void of the cylindrical pipe 41) when pouring concrete, thereby preventing damage to the pile head concrete 4 due to air pockets.

[0020] Figure 7 is a plan view of the pile head concrete 4 and the pile head plate 122, Figure 8 is an oblique view of the pile head concrete 4 and the pile head plate 122, Figure 9 is a plan view of the pile head plate 122 and the lower seismic isolation plate 21, and Figure 10 is an oblique view of the pile head plate 122 and the lower seismic isolation plate 21. 7 and 8, the pile head concrete 4 is provided in the inner space of a resin cylindrical pipe 41. The inner diameter of the cylindrical pipe 41 is larger than the outer diameter of the pile head plate 122, and the cylindrical pipe 41 is installed concentrically with the pile body 11 of the steel pipe pile 1. In addition, the height of the upper end of the cylindrical pipe 41 is aligned with the top edge 122a of the pile head plate 122.

[0021] The cylindrical pipe 41 is installed before the pile head concrete 4 is poured, and the concrete is filled through the gap between the cylindrical pipe 41 and the pile head plate 122 (see FIG. 16). In other words, the cylindrical pipe 41 is also used as a formwork when pouring the concrete. The pile head concrete 4 has a cylindrical shape that is provided along the outer peripheral surface of the pile body head 11H (see Figure 2, etc.), and the upper end surface of the pile head concrete 4 is provided at the same height as the top end 122a of the pile head plate 122. Note that various aggregates can be used as the aggregate for the pile head concrete 4, such as crushed stone, crushed sand, artificial lightweight aggregate, and slag aggregate. In addition, in the illustrated example, a fluororesin sheet 42 is provided along the inner peripheral surface of the cylindrical pipe 41 to reduce friction between the pile head concrete 4 and the cylindrical pipe 41.

[0022] As shown in Figures 2, 9, and 10, the seismic isolation device 2 comprises a lower seismic isolation plate 21 having an upper concave surface 21a on its upper surface, an upper seismic isolation plate 22 having a lower concave surface 22a (see Figure 2) on its lower surface, and a slider 23 arranged between the upper concave surface 21a of the lower seismic isolation plate 21 and the lower concave surface 22a of the upper seismic isolation plate 22, and capable of sliding freely on the upper concave surface 21a and the lower concave surface 22a. The lower seismic isolation plate 21 is made of, for example, steel, and the upper concave surface 21a is configured as a smooth, curved concave surface like a concave lens. Similarly, the upper seismic isolation plate 22 is made of, for example, steel, and the lower concave surface 22a is also configured as a smooth, curved concave surface. The slider 23 is made of, for example, steel, and the upper and lower surfaces are configured as smooth, curved convex surfaces like a convex lens.

[0023] The lower seismic isolation plate 21 is fixed onto the top end 122a of the pile cap plate 122 by the above-mentioned L-shaped anchor bolts 124, and the upper seismic isolation plate 22 is fixed to the underside of the building foundation. The building BD shown in Figure 1 etc. is, for example, a steel frame structure, and the building foundation is, for example, a foundation beam 3 made of H-shaped steel. As shown in Figure 2 etc., the upper seismic isolation plate 22 is fixed to the underside of the foundation beam 3 via, for example, a connecting steel plate 24. The upper seismic isolation plate 22 is fixed using bolts, welding, etc. Therefore, as shown in Figure 3, the load F of the building BD etc. is applied to the steel pipe pile 1 via the upper seismic isolation plate 22, the slider 23, and the lower seismic isolation plate 21, and the steel pipe pile 1 supports the load F. Since the steel pipe pile 1 supports the load F, the pile head concrete 4 does not support the load F.

[0024] 1, 4, and 11, the artificial ground 5 is provided on the ground surface GL and is made of reinforced concrete in this embodiment, but is not limited to reinforced concrete. For example, the artificial ground 5 may be made of concrete. The illustrated artificial ground 5 has a rectangular shape that is slightly larger than the planar shape of the building BD in plan view, and a thickness of 200 to 400 mm, but the planar shape and thickness are not limited to this example. For example, the thickness of the artificial ground 5 may be the same as the height of the pile cap concrete 4. The artificial ground 5 surrounds the bottom of each concrete pile cap 4, and the horizontal position of each concrete pile cap 4 is determined by the artificial ground 5. As described above, the resin cylindrical pipe 41 is provided along the outer periphery of the concrete pile cap 4, so the artificial ground 5 is edged off from the concrete pile cap 4.

[0025] An oil damper 6 is installed between the artificial ground 5 and the foundation beam 3 (building foundation). The oil damper 6 absorbs the energy generated when the artificial ground 5 or the foundation beam 3 moves horizontally, thereby reducing the impact on the building BD in the event of an earthquake. One end of the oil damper 6 is fixed to a rectangular parallelepiped building-side block 31 that protrudes downward from the underside of the foundation beam 3. The building-side block 31 is made of, for example, reinforced concrete. The other end of the oil damper 6 is fixed to a rectangular parallelepiped artificial ground-side block 51 that protrudes upward from the top surface of the artificial ground 5. The artificial ground-side block 51 is also made of, for example, reinforced concrete. The building-side block 31 and the artificial ground-side block 51 are not limited to a rectangular parallelepiped shape as long as each end of the oil damper 6 can be fixed thereto. In this embodiment, the building side block 31 is located at approximately the center position along the planar direction of the building BD, and the artificial ground side blocks 51 are located at four locations: the front, back, left and right of the building side block 31, but this configuration is not limited to this.

[0026] As shown in Figs. 2 and 4, etc., a stopper 7 is provided on the outer periphery of the artificial ground 5 to limit the range of horizontal movement of the building BD. As shown in FIG. 2, the stopper 7 includes a stopper body 7a made of an elastic material such as rubber, and a support member 7b that protrudes upward from the upper surface of the artificial ground 5 and supports the stopper body 7a. As shown in FIG. 2, in this embodiment, four stoppers 7 are provided in front of, behind, left of, and right of the building BD. The stopper 7 can also be installed inside the rigid floorboard (the area surrounded by the foundation beams 3 in plan view).

[0027] As shown in Figure 3, when the ground G moves horizontally due to the occurrence of an earthquake, the artificial ground 5, steel pipe pile 1, and lower seismic isolation plate 21 also move horizontally along with the ground G. At this time, the upper seismic isolation plate 22, on which the load of building BD is applied, tries to maintain the state it was in before the earthquake due to inertial force. The slider 23 slides against the lower seismic isolation plate 21 and the upper seismic isolation plate 22, thereby suppressing the amount of movement of the building BD (upper seismic isolation plate 22) to be less than the amount of movement of the ground G (lower seismic isolation plate 21). In addition, the oil damper 6 suppresses the speed of movement of the building BD. As a result, the horizontal shaking amplitude of the building BD due to an earthquake can be made smaller than the horizontal shaking amplitude of the ground G.

[0028] If the horizontal positions of the lower seismic isolation plate 21 and the upper seismic isolation plate 22 are misaligned, the load of the building BD, etc. will be applied to the outer periphery of the pile head plate 122 through the slider 23 and the lower seismic isolation plate 21, as shown by arrow F. The load F applied to the outer periphery of the pile head plate 122 will tend to bend the pile main body head 11H, but the pile head concrete 4 provided on the outer periphery of the pile main body head 11H can withstand the load F. That is, the pile head concrete 4 receives a reaction force from the ground G to resist the load F and suppress bending of the pile main body head 11H. In this embodiment, the upper end surface of the pile head concrete 4 is flush with the top end 122a of the pile head plate 122, so the pile head concrete 4 can protect the pile main body head 11H from bending. Furthermore, a resin cylindrical pipe 41 and a fluororesin sheet 42 are provided between the concrete pile head 4 and the artificial ground 5, and the concrete pile head 4 and the artificial ground 5 are separated from each other. Therefore, even if a load F is applied to the concrete pile head 4, the cylindrical pipe 41 and the fluororesin sheet 42 make it difficult for the artificial ground 5 to be affected by the load F. As a result, the artificial ground 5 can be protected from damage such as cracks.

[0029] <Construction procedure for the seismic isolation structure of building BD> Next, the construction procedure for the seismic isolation structure of building BD will be explained. Fig. 12 is a diagram showing the state in which the pile main body part 11M has penetrated into the ground G, Fig. 13 is a diagram showing the pile main body head part 11H with the pile head member 12 attached, Fig. 14 is a diagram showing the installed state of the cylindrical pipe 41, Fig. 15 is a diagram showing the state in which reinforcement has been placed in the area where the artificial ground 5 is to be formed, Fig. 16 is a diagram showing the concrete pouring work, Fig. 17 is a diagram showing the state in which the lower seismic isolation plate has been attached, and Fig. 18 is a diagram showing the installation process of the upper seismic isolation plate.

[0030] First, as shown in Fig. 12, the pile body main portion 11M of the pile body 11 is driven into the ground G. A pile driver can be used to drive the pile body 11 into the ground. In this embodiment, the pile main body 11 includes a lower pile 111, an intermediate pile 112, and an upper pile 113. Therefore, after the lower pile 111 is penetrated into the ground G, the upper end of the lower pile 111 and the lower end of the intermediate pile 112 are joined by welding or the like. Next, after the lower pile 111 and the intermediate pile 112 are penetrated into the ground G, the upper end of the intermediate pile 112 and the lower end of the upper pile 113 are joined by welding or the like. Then, the penetration process is completed with the upper end of the upper pile 113, which becomes the pile main body head 11H, protruding above the ground surface GL.

[0031] Next, as shown in Fig. 13, the pile head member 12 is attached to the upper end of the upper pile 113. For example, the upper end of the upper pile 113 is inserted into the inner space of the tubular part 121 of the pile head member 12, and with the position of the bolt insertion hole 122b provided in the pile head plate 122 adjusted, the tubular part 121 and the upper pile 113 are joined by welding or the like. Thereafter, the L-shaped anchor bolt 124 is temporarily fixed in the bolt insertion hole 122b (see FIG. 6). In this embodiment, the bolt insertion hole 122b is pre-formed in the pile head plate 122, but the bolt insertion hole 122b may be formed after the cylindrical portion 121 and the upper pile 113 are joined together.

[0032] Next, as shown in Figure 14, a cylindrical pipe 41 is installed so as to surround the pile head (the combination of the pile main body head 11H and the pile head plate 122) of each steel pipe pile 1 and to be concentric with each steel pipe pile 1. A fluororesin sheet 42 is provided along the inner circumferential surface of the cylindrical pipe 41. The fluororesin sheet 42 may be provided on the cylindrical pipe 41 in advance, or may be provided after the cylindrical pipe 41 is installed. Next, as shown in Fig. 15, reinforcing bars 52 are placed in the area where the artificial ground 5 is to be formed. Although not shown in the drawings, formwork is placed along the outer periphery of the artificial ground 5.

[0033] Next, as shown in Fig. 16, concrete CC is poured into the area where the artificial ground 5 is to be formed and into the inner space of the cylindrical pipe 41. As described above, the fluidized concrete CC is poured into the inner space of the cylindrical pipe 41 through the gap between the cylindrical pipe 41 and the pile cap plate 122, and the state of filling of the concrete CC into the cylindrical pipe 41 is checked through the concrete viewing hole 122c. At this time, the concrete viewing hole 122c also functions as a hole for discharging air from inside the cylindrical pipe 41, so that the pile head concrete 4 is less likely to be damaged by air remaining inside the cylindrical pipe 41. Furthermore, since the cylindrical pipe 41 is used as a formwork for the pile head concrete 4 and continues to be used even after the concrete has hardened, work efficiency is good. The artificial ground side block 51 and the support member 7b provided on the stopper 7 are provided in parallel with the formation of the artificial ground 5 or after the formation of the artificial ground 5.

[0034] After the concrete has hardened, the lower seismic isolation plate 21 is fixed to the top end 122a of the pile cap plate 122, as shown in Fig. 17. The lower seismic isolation plate 21 can be fixed, for example, by removing the nut 124a attached to the upper end of the L-shaped anchor bolt 124, inserting the upper end of the L-shaped anchor bolt 124 into the fixing hole of the lower seismic isolation plate 21 to position it, and then tightening the nut 124a onto the upper end of the L-shaped anchor bolt 124.

[0035] Next, as shown in FIG. 18, a slider 23 is placed on the upper concave surface 21a of the lower seismic isolation plate 21, and the foundation beam 3 to which the upper seismic isolation plate 22 is attached is installed. As shown in Figure 2, by installing the foundation beam 3, the upper seismic isolation plate 22 is positioned directly above the lower seismic isolation plate 21, and a slider 23 is positioned between the upper concave surface 21a of the lower seismic isolation plate 21 and the lower concave surface 22a of the upper seismic isolation plate 22. After each foundation beam 3 is installed, the foundation beams 3 are connected to each other to construct the building foundation, and oil dampers 6 are attached in parallel. Also, stopper bodies 7a are attached to support members 7b of stoppers 7. Thereafter, building BD is constructed on the building foundation.

[0036] <Modification> Figure 19 is a diagram showing a first modified example of the seismic isolation structure, Figure 20 is a diagram showing a second modified example of the seismic isolation structure, Figure 21 is a diagram showing a modified example of the pile head member 12, Figure 21 is a diagram showing a third modified example of the seismic isolation structure, and Figure 22 is a diagram showing a fourth modified example of the seismic isolation structure. In the seismic isolation structure of the above-described embodiment, a resin cylindrical pipe 41 and a fluororesin sheet 42 are interposed between the concrete pile head 4 and the artificial ground 5, but the present invention is not limited to this configuration. For example, as shown in Fig. 19, a gap GP may be provided between the concrete pile head 4 and the artificial ground 5 to separate them.

[0037] Furthermore, as shown in Figure 20, a buffer material 43 may be inserted into this gap GP. For example, high-damping rubber is preferably used as the buffer material 43. Furthermore, as shown in Figure 21, mortar 44 may be filled into this gap GP. By filling the gap with mortar 44, it is possible to cut the edge between the pile cap concrete 4 and the artificial ground 5 while suppressing the growth of weeds and the like. In addition, in the seismic isolation structure of the above-described embodiment, the fluororesin sheet 42 is provided along the inner circumferential surface of the resin cylindrical pipe 41, but the present invention is not limited to this configuration. For example, as shown in Fig. 22, the edge between the pile head concrete 4 and the artificial ground 5 may be separated by interposing the resin cylindrical pipe 41 without providing the fluororesin sheet 42.

[0038] 23(a) and 23(b) are diagrams showing modified examples of the pile head member 12. FIG. In the seismic isolation structure of the above-described embodiment, a set of L-shaped anchor bolt 124 and nut 124a was used to fix the seismic isolation device 2 in order to improve the unity between the pile head member 12 and the pile head concrete 4, but this configuration is not limited to this. For example, as shown in Figures 23(a) and 23(b), a set of a general hexagon bolt 124' and nut 124a may be used to secure the seismic isolation device 2. In the example of Figure 21, the bolt insertion hole 122b and the concrete viewing hole 122c are arranged concentrically, but even with this configuration, the filling status of the poured concrete can be visually confirmed.

[0039] Figure 24(a) is a perspective view of an upper pile 113 equipped with a pile head plate 14, and Figure 24(b) is a perspective view of an upper pile 113 in which a bolt insertion hole 142 and a concrete viewing hole 143 have been drilled in the pile head plate 14. In the seismic isolation structure of the above-described embodiment, the upper pile 113 and the pile head member 12 are configured as separate members, and the upper pile 113 and the pile head member 12 are integrated by welding or the like, but the present invention is not limited to this configuration. For example, as shown in Figure 24(a), the pile head plate 14 may be provided integrally with the upper end of the upper pile 113.

[0040] In the example of FIG. 24( a ), the pile cap plate 14 is made of a disk-shaped steel plate and is welded to the top end of the upper pile 113 . As described above, the steel pipe pile 1 is driven into the ground G by rotating the pile body 11 around its axis. For this reason, the circumferential angle (rotation angle) of the pile cap plate 14 when the steel pipe pile 1 (pile body main portion 11M) is driven to a specified depth is indefinite, and it is difficult to provide the bolt insertion holes 142 shown in Figure 24(b) in the pile cap plate 14 before driving it into the ground G.

[0041] Therefore, in this example, as shown in Figure 24(a), the pile head plate 14 used is not perforated before penetration. Then, after the steel pipe pile 1 is penetrated into the ground G, as shown in Figure 24(b), bolt insertion holes 142 and concrete viewing holes 143 are drilled in the pile head plate 14. This allows the lower seismic isolation plate 21 to be installed in a position suitable for the construction of the building BD.

[0042] In addition, the concrete viewing hole 143 shown in Figure 24(b) has a circular countersink 143b formed on the upper surface of the pile head plate 14 and a viewing hole main body 143a that penetrates the thickness direction from the center of the countersink 143b. Since this concrete viewing hole 143 has a counterbore 143b, the visibility of the concrete CC that has flowed into the concrete viewing hole 143 can be improved.

[0043] In the seismic isolation structure described above, a sliding pendulum type seismic isolation device 2 equipped with a lower seismic isolation plate 21, an upper seismic isolation plate 22, and a slider 23 is used, but other types of seismic isolation devices 2 may also be used. For example, a seismic isolation device 2 equipped with seismic isolation rubber (laminated rubber) may be used, or a seismic isolation device 2 equipped with a sliding bearing may be used. In the above-described seismic isolation structure, the concrete pile head 4 is cylindrical, but the present invention is not limited to this configuration. For example, the concrete pile head 4 may be a square tube with a space in the center through which the pile body head 11H passes. In the above-described seismic isolation structure, the upper end surface of the concrete pile head 4 is flush with the top end 122a of the pile head plate 122, but this configuration is not limiting. For example, the upper end surface of the concrete pile head 4 may be located below the pile head plate 122.

[0044] In the above-described seismic isolation structure, the oil damper 6 is provided between the artificial ground 5 and the building foundation, but the oil damper 6 may be provided as needed. In the seismic isolation structure described above, the foundation beams 3 of a steel frame structure are used as the building foundation, but the present invention is not limited to this configuration. For example, a foundation slab may be used as the building foundation.

[0045] [Summary of embodiments, actions, and effects of the present invention] <First embodiment> The seismic isolation structure of building BD in this embodiment comprises a steel pipe pile 1 having a pile body 11 and a pile head plate 122 provided at the upper end of the pile body 11, and having the pile body main part 11M buried in the ground G so that the pile body head 11H and the pile head plate 122 are provided above the ground surface GL, a seismic isolation device 2 attached between the pile head plate 122 and the foundation beam 3 (building foundation), a pile head concrete 4 provided in a cylindrical shape from the ground surface GL along the outer surface of the pile body head 11H, and an artificial ground 5 provided on the ground surface GL and surrounding the outer periphery of the pile head concrete 4, wherein the pile head concrete 4 suppresses bending of the pile body head 11H when a load is applied to the pile head plate 122 through the seismic isolation device 2, and the artificial ground 5 surrounds at least the lower part of the pile head concrete 4 and is edged off from the pile head concrete 4. According to the seismic isolation structure of the building BD of this embodiment, the pile cap concrete 4 receives a reaction force from the ground G, suppressing bending of the pile main body head 11H. Because the pile cap concrete 4 and the artificial ground 5 are separated from each other, the artificial ground 5 is less susceptible to the effect of the load F received by the pile main body head 11H, and can be protected from damage such as cracks.

[0046] <Second embodiment> In the seismic isolation structure of building BD according to this embodiment, the pile head concrete 4 is arranged from the ground surface GL along the outer peripheral surface of the pile main body head 11H up to the height position of the top end 122a (upper surface) of the pile head plate 122. According to the seismic isolation structure for the building BD of this embodiment, the pile main body head portion 11H can be protected from bending.

[0047] <Third embodiment> The seismic isolation structure of the building BD according to this embodiment is characterized in that a resin cylindrical pipe 41 (a resin hollow member) is interposed between the outer circumferential surface of the pile head concrete 4 and the artificial ground 5. According to the seismic isolation structure of the building BD of this embodiment, the cylindrical pipe 41 can be used as a formwork for the pile head concrete 4, and the cylindrical pipe 41 can continue to be used even after the concrete has hardened, resulting in good work efficiency.

[0048] <Fourth embodiment> The seismic isolation structure of building BD in this embodiment is characterized by the fact that a fluororesin sheet 42 is interposed between the inner surface of a resin cylindrical pipe 41 (a resin hollow member) and the outer surface of the pile head concrete 4. According to the seismic isolation structure of the building BD of this embodiment, a fluororesin sheet 42 is interposed between the cylindrical pipe 41 and the concrete pile head 4, so that the edge between the concrete pile head 4 and the artificial ground 5 can be securely cut off, and the artificial ground 5 can be more reliably protected.

[0049] <Fifth embodiment> In the seismic isolation structure of building BD according to this embodiment, the pile head plate 122 is provided with a concrete viewing hole 122c for visually observing the fluidized concrete CC when pouring the pile head concrete 4, and the concrete viewing hole 122c is characterized by penetrating the thickness of the pile head plate 122. According to the seismic isolation structure of the building BD according to this embodiment, when the pile cap concrete 4 is poured, the filling height of the concrete CC can be easily visually confirmed.

[0050] <Sixth embodiment> The seismic isolation structure of the building BD according to this embodiment is characterized in that an oil damper 6 is provided between the building foundation and the artificial ground 5 to absorb energy when the building foundation and the artificial ground 5 move relative to each other. According to the seismic isolation structure of the building BD according to this embodiment, it is possible to reduce the impact that is applied to the building BD due to the shaking of an earthquake. [Explanation of symbols]

[0051] 1...steel pipe pile, 11...pile body, 11M...main part of pile body, 11H...head part of pile body, 111...lower pile, 112...intermediate pile, 113...upper pile, 12...pile head member, 121...tubular part, 122...pile head plate, 122a...top end (top surface) of pile head plate, 122b...bolt insertion hole, 122c...concrete viewing hole, 123...anchoring bolt, 13...tip blade, 14...pile head plate, 141...top end of pile head plate, 142...bolt insertion hole, 143...concrete viewing hole, 143a...viewing hole body, 143b...counterbore, 2...seismic isolation device, 2 1...lower seismic isolation plate, 21a...upper concave surface of lower seismic isolation plate, 22...upper seismic isolation plate, 22a...lower concave surface of upper seismic isolation plate, 3...foundation beam, 31...building side block, 4...pile head concrete, 41...resin cylindrical pipe, 42...fluororesin sheet, 43...buffer material, 44...mortar, 5...artificial ground, 51...artificial ground side block, 52...reinforcing bar, 6...oil damper, 7...stopper, 7a...stopper body, 7b...support member, BD...building, G...ground, F...load, GP...gap, CC...fluidized concrete

Claims

1. A steel pipe pile having a pile body and a pile head plate provided at the upper end of the pile body, and having a main part of the pile body buried in the ground so that the pile body head and the pile head plate are provided above the ground surface; A seismic isolation device attached between the pile head plate and the building foundation; A pile head concrete provided in a cylindrical shape from the ground surface along the outer peripheral surface of the pile main body head; An artificial ground provided on the ground surface and surrounding the outer periphery of the pile head concrete; Equipped with The pile head concrete suppresses bending of the pile main body head when a load is applied to the pile head plate through the seismic isolation device, A seismic isolation structure for a building, characterized in that the artificial ground surrounds at least the lower part of the pile head concrete and is edged off from the pile head concrete.

2. The seismic isolation structure for a building as described in claim 1, characterized in that the pile head concrete is provided from the ground surface along the outer surface of the pile body head to the height position of the upper surface of the pile head plate.

3. 2. The seismic isolation structure for a building according to claim 1, wherein a hollow resin member is interposed between the concrete pile head and the artificial ground.

4. 4. The seismic isolation structure for a building according to claim 3, wherein a fluororesin sheet is interposed between the inner peripheral surface of the hollow resin member and the outer peripheral surface of the pile head concrete.

5. The pile head plate is provided with a viewing hole for visually observing the fluidized concrete when the pile head concrete is poured, The seismic isolation structure for a building according to claim 1, characterized in that the viewing hole penetrates the pile head plate in the thickness direction.

6. The seismic isolation structure for a building according to claim 1, characterized in that a damper is provided between the building foundation and the artificial ground to absorb energy when the building foundation and the artificial ground move relative to each other.

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