JP2019007297A - Bridge pier foundation structure - Google Patents

Abstract

To provide a footingless bridge pier foundation structure having sufficient strength and rigidity for a bridge pier having a plurality of pillars.SOLUTION: A bridge pier foundation structure 10 for supporting a bridge pier 1 having a plurality of steel pipe columns 2 erected on a foundation X comprises: a plurality of piles 11 provided for one steel pipe column 2 of the plurality of steel pipe columns 2 and spaced apart in the horizontal direction; and at least one connector 12 provided in the foundation X, and connecting the plurality of piles 11 to each other. A lower end portion 2a of the one steel pipe column 2 is linked to a pile head 11a of the plurality of piles 11.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a pier foundation structure, and more particularly to a pile foundation structure provided for a pillar of a pier.

  As a viaduct pier used for structures such as roads and railways, a structure called a multi-column pier having a plurality of columns is known. As an example, a steel pipe aggregate pier having a three-dimensional structure in which a plurality of steel pipes and the like are used as pillars and these pillars are connected to each other by horizontal members or diagonal members. Generally, the pier is supported on the ground by a foundation. When the ground is solid, a reinforced concrete plate called a footing that directly contacts the ground may be used. However, for example, when the ground is soft, a pile foundation is often employed. As a pile foundation structure, for example, a structure described in Patent Document 1 is known. In this pile foundation structure, a plurality of piles are connected by a connector embedded in the ground.

  Examples of the pile used for the pile foundation structure include a steel pipe pile or a PHC (Pretensioned Spun High-strength Concrete) pile. For example, in Non-Patent Document 1, one steel pipe pile is connected to one steel pipe column of a steel pipe assembled pier, and the load from the superstructure or the pier is directly applied to the pile foundation without using a footing. The structure to transmit (structure of 1 pillar 1 pile type) is described. Patent Document 2 also describes a similar structure in which a steel pipe column and a steel pipe pile are connected in the vertical direction in a multi-column pier and footing is omitted. A structure in which a footing is omitted (a structure without a footing) can have several advantages over a structure with a footing.

JP 2013-2050 A JP 2008-303598 A

Seiji Shinohara, 3 others, “Structure proposal and earthquake response analysis of pile foundation integrated steel pipe piers”, JSCE Proceedings C (Geosphere Engineering), 2013, Vol. 69, no. 3, p. 312-325

  Regarding the footing-less structure for multi-column piers such as steel pipe aggregate piers, further improvements are desired in terms of strength and rigidity. In reality, the structure of the above-mentioned single pillar and one pile type may not always be optimal. Accordingly, an object of the present invention is to provide a footing-less pier foundation structure having sufficient strength and rigidity for a pier having a plurality of columns.

  One aspect of the present invention is a pier foundation structure that supports a pier having a plurality of columns erected on the ground, and is provided for one of the plurality of columns and spaced apart in the horizontal direction. A plurality of piles to be provided, and at least one connecting tool that is provided in the ground and connects the plurality of piles to each other, and a lower end portion of one pillar is coupled to a pile head of the plurality of piles It is characterized by that.

  According to this pier foundation structure, a plurality of piles are provided for one column among a plurality of columns of the pier. The plurality of piles are connected by a connector. Thereby, sufficient intensity | strength as a pile foundation structure is ensured. And the pile heads of a plurality of piles are combined with the lower end part of one pillar. In this way, piers with sufficient strength and rigidity are provided by providing pillars and piles in a one-to-many correspondence rather than a one-to-one correspondence, and by connecting the lower end of the pillar to each pile head. A foundation structure is provided. Such a pile foundation structure composed of a plurality of piles exhibits excellent horizontal rigidity even on the ground that can be fluidized. Moreover, since a pile is directly couple | bonded with a pillar, footing is abbreviate | omitted and can enjoy the advantage which a footing-less structure has.

  The coupling tool may include a coupling portion that extends between the plurality of piles and a plurality of engagement portions that are provided at end portions in the extending direction of the coupling portion and engage with the plurality of piles. In this case, the degree of freedom in design is increased by changing the direction and position of the connecting portion according to the required strength and rigidity.

  The plurality of piles may have a circular tube with the same diameter, and one column may be provided such that the axis of the one column is located at the center of the axis of the plurality of piles. In this case, since the coupled state of the pillars to each pile can be made uniform, it is easy to ensure strength and rigidity.

  The plurality of piles are two piles, and the two piles may be arranged so as to sandwich the diameter of one pillar. In this case, since one pillar is sandwiched between two piles, strength and rigidity are improved. In particular, the horizontal rigidity is increased in the direction in which the two piles are arranged. In the construction method of the pier foundation structure, for example, a connecting portion can be installed in advance, and using this as a guide, the ground can be drilled with a multi-axis auger or the like to drive a pile.

  A plurality of piles are three or more piles, and the three or more piles may be arranged at the position of the apex of the regular polygon. In this case, the horizontal rigidity can be increased in a plurality of directions. Overall, strength and rigidity are increased.

  The ground has a flow direction in the lateral flow accompanying liquefaction during an earthquake, and any two of the plurality of piles connected by the connector may be arranged in the flow direction. . In this case, a highly rigid pile foundation structure is realized for the fluidizable ground.

  The ground has a flow direction in the lateral flow associated with liquefaction during an earthquake, and a plurality of connectors are provided for a plurality of piles. The number of connecting tools provided may be the largest. In this case, a highly rigid pile foundation structure is realized for the fluidizable ground. When the connector is provided so as to cross the flow direction, the connector can be a resistance at the time of ground flow, but since there are the most connectors provided along the flow direction, The resistance is reduced, and the horizontal rigidity is increased with respect to the flow direction.

  ADVANTAGE OF THE INVENTION According to this invention, the pier foundation structure with sufficient intensity | strength and rigidity is provided, and also the advantage which a footing-less structure has can be enjoyed.

It is a perspective view which shows the 1st structural example of the pier foundation structure which concerns on one Embodiment of this invention. It is a perspective view which shows schematic structure of the pile head vicinity of the pier foundation structure of FIG. It is sectional drawing which follows the III-III line of FIG. 2, and is a figure which shows an example of the coupling | bonding form of a pile and a pillar. FIG. 4A is a diagram illustrating deformation at the time of an earthquake in the pier foundation structure according to the embodiment, and FIG. 4B is a diagram illustrating deformation at the time of an earthquake in a conventional pier foundation structure having a footing. It is a perspective view which shows the 2nd structural example (when there are three piles) of a pier foundation structure. It is sectional drawing which shows an example of the coupling | bonding form of the pillar and a pile in the pier foundation structure of FIG. It is a perspective view which shows the 3rd structural example (in the case of four piles) of a pier foundation structure. It is sectional drawing which shows an example of the coupling | bonding form of the pillar and a pile in the pier foundation structure of FIG. It is a perspective view which shows the connection structure of the piles of the pier foundation structure which concerns on a deformation | transformation form. Fig.10 (a) and FIG.10 (b) are figures which show the other example of the coupling | bonding form of a pillar and a pile, respectively. It is a perspective view which shows the connection structure of the piles of the pier foundation structure which concerns on another modification. It is sectional drawing which shows schematic structure of the pile head vicinity of the pier foundation structure which concerns on other embodiment of this invention. It is a perspective view which shows schematic structure of the pile head vicinity of the pier foundation structure of FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant descriptions are omitted.

  First, a pier 1 to which a pier foundation structure 10 according to an embodiment is applied and a pier foundation structure 10 that supports the pier 1 will be described with reference to FIG. FIG. 1 is a perspective view showing a first configuration example of a pier foundation structure 10 according to an embodiment of the present invention. As shown in FIG. 1, the pier 1 is for supporting a viaduct provided for a ground structure such as a road or a railroad. The pier 1 is a steel pipe assembly pier (or a multi-column pier) having a plurality of steel pipe columns 2. A plurality of (for example, four) cylindrical steel pipe columns 2 are erected in parallel with each other on the ground X (see FIG. 4). The plurality of steel pipe columns 2 are arranged so as to be aligned in the bridge axis direction and the bridge axis perpendicular direction. In addition, the number and arrangement | sequence of the some steel pipe pillar 2 are not restricted to this aspect.

  Two adjacent steel pipe columns 2 are connected by a horizontal connecting member 3 extending in the horizontal direction. The horizontal connecting material 3 is made of a steel plate, and is joined to the two steel pipe columns 2 by, for example, welding. The horizontal connecting material 3 resists a horizontal load when an earthquake occurs. Damage at the time of the occurrence of an earthquake is easily concentrated on the horizontal connecting material 3, thereby suppressing damage to the steel pipe column 2. The pier 1 may be a steel pipe aggregate pier in which a structure different from the above is adopted. The horizontal connecting material 3 may be provided obliquely with respect to the horizontal direction. The horizontal connecting material 3 may be omitted.

  A beam portion 4 connected to the upper structure is provided at the upper end portion of the pier 1. A pier foundation structure 10 is connected to the lower end of the pier 1, that is, the lower end 2 a of the steel pipe column 2. The pier foundation structure 10 is a pile foundation structure that is provided on the relatively soft ground X and supports the pier 1.

  As shown in FIGS. 1 and 2, in the pier foundation structure 10, a plurality of piles 11 for supporting the steel pipe column 2 is provided for one steel pipe column 2. In the present embodiment, the same pier foundation structure 10 is provided for each steel pipe column 2. For example, two circular tubular piles 11 spaced apart in the horizontal direction are connected to one steel pipe column 2. The two piles 11 are, for example, steel pipe piles having the same diameter and length. The two piles 11 are provided such that their axial centers Lb (see FIG. 3) are parallel to each other. In the pier 1 and the pier foundation structure 10, both the axis La (see FIG. 3) of the steel pipe column 2 and the axis Lb of the pile 11 extend in the vertical direction. Each pile head 11 a of the two piles 11 is coupled to the lower end portion 2 a of one steel pipe column 2. Note that the pile 11 may be a PHC pile or the like. The arrangement and connection form of the plurality of piles 11 with respect to the steel pipe column 2 will be described later.

  When the pile 11 is a steel pipe pile, the diameter of the pile 11 is 1,600 mm or less, for example. In addition, when the pile 11 is a PHC pile, the diameter of the pile 11 is 1200 mm or less, for example, However, About 1000 mm thru | or 800 mm may be sufficient. Whether the pile 11 is a steel pipe pile or a PHC pile, a relatively small-diameter pile is used, so that the construction machine can be small.

  The pier foundation structure 10 of this embodiment includes a connector 12 that connects a plurality of piles 11 to each other. In the pier foundation structure 10, a plurality of connectors 12 are provided for the two piles 11. The plurality of connectors 12 are installed at predetermined intervals in the vertical direction. The connector 12 extends in the horizontal direction, for example, and both ends in the horizontal direction are coupled to the two piles 11. The connector 12 is provided in the ground X and increases the horizontal rigidity of the pier foundation structure 10.

  Each connector 12 includes two cylindrical sockets (engagement portions) 13 through which each of the two piles 11 passes, and a connection plate (connection portion) 14 that connects the sockets 13 to each other. The axial center of the socket 13 substantially coincides with the axial center Lb of the pile 11. A gap between the socket 13 and the pile 11 is filled with cement milk or mortar. Thereby, the socket 13 is coupled (engaged) to the pile 11. The connecting plate 14 is a thin plate-like member that extends in the horizontal direction between the two piles 11 and extends, for example, along a vertical plane. The two sockets 13 are joined to both ends of the connecting plate 14 in the horizontal direction (extending direction). In the example shown by FIG. 1 and FIG. 2, the some connector 12 has couple | bonded the several pile 11 in the grid | lattice form.

  Unlike the connector described in Patent Document 1, these connectors 12 are provided on the ground X in advance of the pile 11 or simultaneously with the pile 11. The construction method of the pier foundation structure 10 will be described later.

  As shown in FIGS. 2 and 3, the two piles 11 are arranged so as to sandwich the diameter of one steel pipe column 2. The axial center La of the steel pipe column 2 is located at the center of the axial centers Lb and Lb of the two piles 11 having a circular tube with the same diameter. In the pier foundation structure 10 in which the plurality of piles 11 are coupled to the steel pipe column 2, the distance between the piles 11 and the piles 11 corresponds to the diameter of the steel pipe column 2. That is, the space | interval of the pile 11 and the pile 11 is set to the magnitude | size which the coupling | bonding of the pile 11 with the steel pipe pillar 2 is possible. When two piles 11 are used, the distance between the piles 11 and the piles 11 may be the same as the diameter of the steel pipe column 2 or 1.2 times or less the diameter of the steel pipe column 2 and Also good. In the present specification, the “interval” with respect to the pile 11 means an interval between the outer peripheral surfaces of the pile 11 (not the axial center La).

  The lower end portion 2 a of the steel pipe column 2 and the pile head portion 11 a of the pile 11 are coupled by a coupling portion 20. As the coupling portion 20, various known coupling forms can be adopted. For example, as shown in FIG. 3, a steel pipe joint structure (a joint structure described in JP 2007-40053 A) in which a male joint 22 is fitted to a female joint 21 may be used. The female joint 21 and the male joint 22 extend in the vertical direction over a predetermined length. A rod-like steel material or the like may be provided on the outer peripheral surface of the pile 11, and a spacer or the like as a spacing member may be provided between the claw portion of the male joint 22 and the pile 11 (both not shown). A space formed by the female joint 21 and the male joint 22 may be filled with mortar or the like.

  In the pier foundation structure 10 in which a plurality of piles 11 are connected to each other and the piles 11 are coupled to the lower end 2a of the steel pipe column 2, no footing is provided, and a footing-less structure is realized. . The lower end 2a of the steel pipe column 2 may be filled with concrete 7. When the pile 11 is a steel pipe pile, the concrete 17 may be filled in the pile head 11 a inside the steel pipe 16. In that case, the concrete portion 11b (see FIG. 1) of the pile 11 may not be filled with the concrete 17.

  In the pier foundation structure 10, the direction of lateral flow accompanying liquefaction during an earthquake is further considered. Depending on the ground X, the flow direction D of the lateral flow may be specified. The two piles 11 are arranged so as to sandwich the diameter of the steel pipe column 2 as described above, but these two piles 11 are arranged in the flow direction D (see FIG. 3). The connecting plate 14 of the connecting tool 12 is provided so as to substantially coincide with the flow direction D. With a rational structure that takes into account the direction of lateral flow, a pile foundation structure with sufficient rigidity and strength against the flow of the ground X is realized.

  In FIG. 1, although the example which has arrange | positioned so that two piles 11 may be arranged in a bridge axis orthogonal direction with respect to the steel pipe pillar 2 of the pier 1 is shown, arrangement | positioning of the some pile 11 is not restricted to this, It can be set appropriately. That is, when the flow direction D is specified, the arrangement of the plurality of piles 11 can be set based on the flow direction D. In other words, the arrangement of the plurality of piles 11 may be set regardless of the direction of the bridge axis or the direction perpendicular to the bridge axis.

  Then, the construction method (construction method) of the pier foundation structure 10 is demonstrated. First, the connector 12 is temporarily placed on the ground X. The pile 11 is driven into the socket 13 using the socket 13 of the connector 12 as a guide. After that, the necessary number of connectors 12 are sequentially pressed into the ground. Various methods such as Nakabori method, embedding method, impact method, press-fitting method, and a combination of these methods can be applied to placing the pile 11. When the rotation method of the winged steel pipe pile is applied, it is built after inserting the tip pile into the socket 13, and after the intermediate pile, the pile can be added and placed.

  In addition to the above-mentioned various construction methods, when constructing the pier foundation structure 10 composed of two piles 11, even if ground agitation is performed using a multi-axis auger used for construction of a continuous columnar underground wall Good. That is, a multi-shaft auger is used to drill a hole in the soil, and the ground is made into a slurry by mixing and stirring the excavated soil and cement milk. The two piles 11 in which a plurality of connecting tools 12 are installed and fixed in advance to form a ladder shape may be built in the ground in a slurry state. In that case, the connector 12 is not press-fitted into the ground.

  The gap (space) between the socket 13 of the connector 12 and the pile 11 is washed with a jet, and the gap is filled with cement milk or mortar.

  According to the pier foundation structure 10 of the present embodiment, a plurality of piles 11 are provided for one steel pipe column 2 among the plurality of steel pipe columns 2 of the pier 1. The plurality of piles 11 are connected by a connector 12. Thereby, sufficient intensity | strength as a pile foundation structure is ensured. The pile heads 11 a of the plurality of piles 11 are coupled to the lower end 2 a of one steel pipe column 2. As described above, the steel pipe columns 2 and the piles 11 are provided in a one-to-many correspondence relationship instead of a one-to-one correspondence relationship, and the lower end portion 2a of the steel pipe column 2 is coupled to each pile head portion 11a. A bridge pier foundation structure 10 having strength and rigidity is provided. Such a pile foundation structure composed of a plurality of piles 11 exhibits excellent horizontal rigidity even for the ground X that can be fluidized. Moreover, since the pile 11 is directly couple | bonded with the steel pipe pillar 2, the footing is abbreviate | omitted and can enjoy the various advantages which a footing-less structure has.

  For example, the pier foundation structure 10 shown in FIG. 4 (a) has advantages over the conventional structure with footing shown in FIG. 4 (b). As shown in FIG. 4B, the pier foundation structure 100 includes a pier 101 including a plurality of steel pipe columns 102, a horizontal connecting member 103, and a beam portion 104. The pier 101 includes a pile 105 and a footing. 106. Since the footing 106 is rigid and does not deform, the deformation of the horizontal connecting member 103 (horizontal member) arranged in the vicinity thereof can be smaller than the deformation of the middle connecting member 103 (horizontal member) in the middle stage of the pier 101. On the other hand, as shown in FIG. 4 (a), in the pier foundation structure 10, the entire structure from the steel pipe column 2 to the pile 11 of the pier 1 is gently deformed. 3 (horizontal material) can be deformed to the same extent as the middle horizontal connecting material 3.

  Furthermore, according to the pier foundation structure 10, the pulling-out resistance of the pile 11 can be increased. Thereby, for example, rotational deformation of the pier 1 can be suppressed.

  For the connection between the piles 11, a connector 12 including a connecting plate 14 and a socket 13 is used. In this case, the degree of freedom in design is increased by changing the direction and position of the connector 12 according to the required strength and rigidity.

  Since one steel pipe column 2 is provided so that its axis La is located at the center of the axis Lb of the plurality of piles 11, the combined state of the steel tube columns 2 with respect to the respective piles 11 can be made uniform. Thereby, it is easy to ensure strength and rigidity.

  Since one steel pipe column 2 is sandwiched between two piles 11, strength and rigidity are enhanced. Particularly, the horizontal rigidity is enhanced in the direction in which the two piles 11 are arranged. In the construction method of the pier foundation structure 10, it is also possible to install the connecting tool 12 in advance and drill the ground by drilling the ground with a multi-axis auger or the like using this as a guide.

  Furthermore, when the ground X has the flow direction D accompanying the liquefaction at the time of an earthquake, the two piles 11 connected by the connector 12 are located in the flow direction D. In this case, a highly rigid pile foundation structure is realized for the ground X that can be fluidized.

  According to the pier foundation structure 10, although it is a pile foundation including a large number of piles 11, the horizontal rigidity is much higher than that of a pile foundation structure having the same number of piles as the steel pipe columns 2 (one-pillar-one-pile structure). It is getting higher. If the underground part of the pile 11 is made of concrete, the durability is further enhanced.

  By using the relatively small-diameter pile 11, the construction machine can be small. The individual piles 11 can be constructed with the usual combination of Nakabori. By driving the connector 12 including the socket 13 as a guide, the construction error at the pile position can be reduced.

  By appropriately setting the interval between the piles 11, it is possible to easily cope with the diameter of the steel pipe column 2. Therefore, the freedom degree of selection of the diameter of the steel pipe pillar 2 and the pile 11 is high.

  The bridge support function after the earthquake can be maintained by causing the connecting plate 14 of the connecting tool 12 to yield ahead of the pile 11.

  By securing the strength and rigidity of the pile 11, it is possible to prevent damage to underground members that are difficult to inspect and repair after an earthquake. At the same time, since there is no rigid footing, the deformation of the horizontal material in the vicinity of the footing of the steel pipe gluing pier with the conventional structure can be increased (see FIG. 4A), and the energy absorption performance of the entire lower structure is improved. be able to.

  Next, another configuration example of the pier foundation structure 10 will be described. FIG. 5 is a perspective view showing a second configuration example (in the case of three piles 11) of the pier foundation structure. FIG. 6 is a cross-sectional view showing an example of a coupling form of the steel pipe column 2 and the pile 11 in the pier foundation structure of FIG. As shown in FIGS. 5 and 6, in this pier foundation structure, three piles 11 are provided for one steel pipe column 2. A plurality of coupling tools 12A (only the uppermost coupling tool 12A is shown in FIG. 5) is provided for the three piles 11.

  The connector 12 </ b> A includes three cylindrical sockets (engagement portions) 13 through which each of the three piles 11 passes, and three connection plates (connection portions) 14 that connect the sockets 13 to each other. The coupling form of the connector 12A to each pile 11 is the same as that in the first configuration example described above.

  In this pier foundation structure, the three piles 11 are arranged at the positions of the vertices of equilateral triangles. That is, the axis Lb of the three piles 11 is located at the apex of the equilateral triangle in the cross section perpendicular to the axis Lb. The axial center La of the steel pipe column 2 is located at the center of the axial center Lb of the three piles 11 having a circular tube with the same diameter. The interval between the pile 11 and the pile 11 is set to a size that allows the pile 11 to be coupled to the steel pipe column 2. When three piles 11 are used, the distance between the piles 11 and the piles 11 may be the same as the diameter of the steel pipe column 2 or may be equal to or less than the diameter of the steel pipe column 2. By appropriately adjusting the distance between the three piles 11, the diameter of the steel pipe column 2 can be easily accommodated.

  As shown in FIG. 6, the lower end portion 2 a of the steel pipe column 2 is disposed between the three piles 11 and is surrounded by the three piles 11 and the connector 12 </ b> A. Each pile head portion 11a of the three piles 11 is coupled to the lower end portion 2a of the single steel pipe column 2 via the coupling portion 20A. The embedded length of the lower end portion 2 a of the steel pipe column 2 may be about 1 to 2 times the diameter of the steel pipe column 2.

  Hereinafter, the coupling | bonding form (20A of coupling | bond parts) of the pile 11 with respect to the steel pipe pillar 2 is demonstrated. A plurality of steel plate dowels 18 are fixed to the outer peripheral surface of the steel pipe column 2 by welding or the like. A plurality of holes may be formed in the steel plate dowel 18. The plurality of holes may be arranged in one or a plurality of rows in the axial direction. The steel plate gibber 18 is vertically attached to the outer peripheral surface of the steel pipe column 2. The steel plate dowel 18 may be disposed at a position having a large gap in the circumferential direction of the steel pipe column 2. By such an arrangement, the steel plate dowel 18 protruding from the outer periphery of the steel pipe column 2 can be arranged without any trouble. A connecting material 23 such as mortar or concrete is placed between the connector 12 </ b> A and the steel pipe column 2, and the steel pipe column 2 and the pile 11 are integrated by the binding material 23. This structure is the same whether the pile 11 is a steel pipe pile or a PHC pile. A flat bar 19 as a spacing member may be fixed to the inner peripheral surface of the socket 13.

  The structure using the steel plate gibber 18 has the advantage that there is no cross-sectional defect of the steel pipe column 2 itself and the manufacturability is good.

  The construction method (construction method) of the pier foundation structure will be described. The connector 12A including the socket 13 is installed on the ground X, and the pile 11 is placed using the connecting tool 12A as a guide. The gap between the socket 13 and the pile 11 is filled with grout, mortar, or the like (not shown), and the connector 12A and the pile 11 are integrated. In addition, when arrange | positioning connecting tool 12A in the underground deep part, after piled up connecting tool 12A on connecting tool 12A, pile 11 may be laid and press fitting tool 12A into the underground part. Next, the portion of earth and sand surrounded by the connector 12 </ b> A is excavated, the steel pipe column 2 is built, a binding material 23 such as mortar or concrete is placed, and the steel pipe column 2 and the pile 11 are integrated.

  Also by the pier foundation structure having the three piles 11, the same operation and effect as the first configuration example described above are exhibited. In particular, since the steel pipe column 2 is erected at the center of the three piles 11 arranged at the position of the triangle in plan view, the diameter of the steel pipe column 2 can be easily accommodated.

  According to the pile 11 arranged at the position of the apex of the regular triangle (regular polygon), the horizontal rigidity can be increased in a plurality of directions. Overall, strength and rigidity are increased.

  In addition, as a coupling | bonding form of the pile 11 with respect to the steel pipe pillar 2, another coupling | bonding form (shift prevention) may be used. For example, a method of welding a deformed reinforcing bar or a headed stud to the surface of the steel pipe column 2 and a method of making the steel pipe column 2 itself a steel material having irregularities on the surface of a striped steel plate or the like can be mentioned. In this embodiment, any method can be applied. It can be appropriately designed according to the embedding length and thickness of the steel pipe column 2 and the strength of the filled concrete.

  Moreover, you may provide a some hole in steel pipe pillar 2 itself. Regardless of whether the above-described perforated steel plate gibber 18 is used or a hole is provided in the steel pipe column 2, it is also possible to arrange a reinforcing bar penetrating the hole to increase the shear strength. The form which provides a hole in the steel pipe column 2 has the advantage that the steel pipe column 2 can be arranged and coupled to the pile 11 even if there is no room in the space surrounded by the connector 12A and the steel pipe column 2. . In addition, since a cross-sectional defect | deletion will arise in steel pipe column 2 itself if a hole is provided in steel pipe column 2, it is necessary to make allowance for the stress which generate | occur | produces in steel pipe column 2. FIG.

  Subsequently, still another configuration example of the pier foundation structure 10 will be described. FIG. 7 is a perspective view showing a third configuration example (in the case of four piles 11) of the pier foundation structure. FIG. 8 is a cross-sectional view showing an example of a coupling form of the steel pipe column 2 and the pile 11 in the pier foundation structure of FIG. As shown in FIGS. 7 and 8, in this pier foundation structure, four piles 11 are provided for one steel pipe column 2. A plurality of coupling tools 12B (only the uppermost coupling tool 12B is shown in FIG. 7) is provided for the four piles 11.

  The connector 12B includes four cylindrical sockets (engagement portions) 13 through which each of the four piles 11 penetrates, and four connection plates (connection portions) 14 that connect the sockets 13 to each other. The coupling form of the connector 12B with respect to each pile 11 is the same as the first configuration example and the second configuration example described above.

  In this pier foundation structure, the four piles 11 are arranged, for example, at the positions of square apexes. That is, the axis Lb of the four piles 11 is located at the apex of the square in the cross section perpendicular to the axis Lb. The axis La of the steel pipe column 2 is located at the center of the axis Lb of the four piles 11 having a circular tube with the same diameter. The interval between the pile 11 and the pile 11 is set to a size that allows the pile 11 to be coupled to the steel pipe column 2. When four piles 11 are used, the distance between the piles 11 and the piles 11 may be approximately the same as the diameter of the steel pipe column 2 or may be equal to or less than the diameter of the steel pipe column 2. When four piles 11 are used, the interval between the piles 11 can be narrowed compared to the diameter of the steel pipe column 2 because the number of the piles 11 is large.

  As shown in FIG. 8, the lower end portion 2a of the steel pipe column 2 is disposed between the four piles 11 and is surrounded by the four piles 11 and the connector 12B. Each pile head portion 11a of the four piles 11 is coupled to the lower end portion 2a of one steel pipe column 2 via the coupling portion 20B. The embedded length of the lower end portion 2 a of the steel pipe column 2 may be about 1 to 2 times the diameter of the steel pipe column 2.

  The connection form of the pile 11 to the steel pipe column 2 and the construction method (construction method) of the pier foundation structure are the same as those in the second configuration example described above. Also in this third configuration example, a steel plate gibber 18 or the like can be used.

  In the pier foundation structure having four piles 11, the couplers 12 and 12B may be provided in consideration of the flow direction D accompanying liquefaction during an earthquake. That is, the connecting tool 12B including the four sockets 13 and the four connecting plates 14 as described above may be used, but in addition to or instead of the two sockets 13 and two. The connecting tool 12 of the first configuration example including the connecting plate 14 may be used. The four piles 11 may be arranged in a square in plan view, and a plurality of connectors 12 may be provided for the four piles 11. Of the plurality of connectors 12, the number of connector plates 14 (connectors 12) provided along the flow direction D may be the largest. Thereby, a plane truss having high strength and rigidity with respect to the flow direction D is formed. Note that the connecting plate 14 (connector 12) provided along the direction perpendicular to the flow direction D has a minimum number of steps.

  Also by the pier foundation structure having the four piles 11, the same operations and effects as the first configuration example and the second configuration example described above are exhibited.

  Moreover, a highly rigid pile foundation structure is implement | achieved with respect to the ground X which can be fluidized. When the connecting tool 12 is provided so as to cross the flow direction D, the connecting tool 12 can be a resistance when the ground flows, but the number of the connecting tools 12 provided along the flow direction D is the largest. The resistance at the time of ground flow is reduced, and the horizontal rigidity with respect to the flow direction D is increased.

  The extending direction of the connecting plate 14 in the connecting tools 12, 12A, 12B is not limited to the horizontal direction. FIG. 9 is a perspective view showing a connection structure between the piles 11 of the pier foundation structure 10C according to a modified embodiment. As shown in FIG. 9, in the pier foundation structure 10 </ b> C, the connection plate 14 of the connector 12 </ b> C extends between the pile 11 and the pile 11 in a direction that forms an angle (acute angle) with respect to the horizontal direction. Yes. Thereby, the height of the socket 13 differs in one connection tool 12C. A plurality of couplers 12C may be provided so as to be alternately stacked upside down. In the example shown in FIG. 9, the plurality of couplers 12 </ b> C join the plurality of piles 11 in a planar truss shape. In the pier foundation structure having two, three, or four piles 11, such a planar truss-like connection structure may be formed.

  The plane truss-like pier foundation structure can be constructed (constructed) in the same manner as the above-described pier foundation structure 10. When constructing the pier foundation structure 10 </ b> C composed of the two piles 11, ground agitation using a multi-axis auger used for construction of the continuous columnar underground wall may be performed. That is, a multi-shaft auger is used to drill a hole in the soil, and the ground is made into a slurry by mixing and stirring the excavated soil and cement milk. Two piles 11 having a planar truss shape may be built by previously installing and fixing a plurality of connecting tools 12C on the ground in a slurry state. In that case, the connector 12C is not press-fitted into the ground.

  According to the planar truss-like connection structure, bending of the pile 11 during an earthquake is reduced. Further, in consideration of the flow direction D, a large number of planar truss-like connection structures may be provided along the flow direction D.

  With reference to FIG. 10, the other example of the coupling | bonding form of the steel pipe pillar 2 and the pile 11 is demonstrated. As shown in FIG. 10 (a), even when a coupling portion 20D using a coupling member 26 in which one pillar hole 26a and a plurality of (for example, two) pile holes 26b are formed is employed. Good. The hole 26a for pillar respond | corresponds to the diameter of the steel pipe pillar 2, and the lower end part 2a of the steel pipe pillar 2 can be inserted. The pile hole 26b corresponds to the diameter of the pile 11, and the pile head 11a of the pile 11 can be inserted therein. The arrangement of the steel pipe columns 2 and the piles 11 shown in FIG. 10 is the same as the arrangement of the steel pipe columns 2 and the piles 11 shown in FIG. The coupling member 26 has, for example, an oval (or oval or circular) outer shape that surrounds the pillar hole 26a and the pile hole 26b. The coupling member 26 is made of, for example, high-strength concrete and has a spiral reinforcing steel material (not shown) embedded therein. The steel pipe column 2 and the pile 11 are respectively inserted into the column hole 26a and the pile hole 26b of the coupling member 26 which is such a lotus root-shaped member, and grout or mortar is cast and integrated between the gaps. .

  When constructing the joint portion 20D, the surface of the ground X is excavated, the joint member 26 is first installed, and the two piles 11 are driven and integrated using the pile hole 26b as a guide. Next, the steel pipe column 2 is installed. In this case, both the steel pipe pile and the PHC pile can be used. The embedded length of the lower end portion 2 a of the steel pipe column 2 may be about 1 to 2 times the diameter of the steel pipe column 2. In the case where the pillar 2 and the pile 11 are steel pipes, in-fill concrete is placed in a portion where the steel pipe pillar 2 and the pile 11 are embedded in the coupling member 26.

  In addition, when arrange | positioning the coupling tool 12 in the underground deep part, after pile | stacking the coupling member 26 on the coupling tool 12, the pile 11 may be driven and the coupling tool 12 may be press-fitted in the underground part. Next, the earth and sand of the column hole 26a of the coupling member 26 is excavated, the steel pipe column 2 is built, and a coupling material 23 such as mortar or concrete is placed to integrate the steel pipe column 2 and the coupling member 26.

  In the case of using the coupling member 26, unevenness may be provided on the surfaces of the steel pipe column 2 and the pile 11 to increase the displacement resistance. In the case of a PHC pile, the surface may be roughened, or irregularities may be added during manufacture. In the case of a steel pipe pile, a deformed bar or a round steel bar may be welded to the surface in a direction perpendicular to the axis of the steel pipe.

  Further, as shown in FIG. 10B, the column hole 26a and the pile hole 26b may not be independent holes but may be holes communicating with each other.

  The connector is not limited to the one including the socket 13. With reference to FIG. 11, the connection structure of the piles of the pier foundation structure which concerns on another modification is demonstrated. As shown in FIG. 11, the pile 11 and the pile 11 include a connecting material (connecting portion) 32 extending therebetween, and engaging portions 33 provided at both ends in the extending direction of the connecting material 32. May be connected by a steel plate connector 30 including The T-shaped engaging portion 33 is engaged with a female joint 31 provided on the outer peripheral surface of the pile 11. The female joint 31 may be a steel pipe sheet pile joint. The connection tool 30 may have a structure that can be inserted into the ground later. The space formed by the female joint 31 and the engaging portion 33 of the connector 30 may be filled with mortar or the like.

  According to the connection structure using the connection tool 30 having the engaging portions 33 that engage with the female joint 31 at both ends, the rigidity of the entire pile 11 is increased as in the connection structure including the socket 13 described above. Further, by using a steel pipe sheet pile joint, the connecting tool 30 can be easily inserted even after the pile 11 is driven. There is no need to divide the pile into upper and lower parts. As shown in FIG. 11, the connecting material 32 can be easily provided in all the vertical, horizontal, and diagonal directions. Any of the grid-like connecting structure shown in FIG. 2, the triangular connecting structure shown in FIG. 5, the quadrangular connecting structure shown in FIG. 7, and the planar truss-like connecting structure shown in FIG. Can be formed.

  Next, a pier foundation structure according to another embodiment will be described with reference to FIGS. 12 and 13. FIG. 12 is a cross-sectional view showing a schematic structure in the vicinity of a pile head 11a of a pier foundation structure according to another embodiment. FIG. 13 is a perspective view showing a schematic structure in the vicinity of the pile head 11a of the pier foundation structure. As shown in FIG. 12, in this pier foundation structure, four piles 11 are provided for one steel pipe column 2. The pile 11 is a steel pipe pile, for example. A plurality of coupling tools (not shown) are provided for the four piles 11. Any of the above-described connectors may be used as a connector for connecting the piles 11 to each other. When the connector 12 including the socket 13 is used, the connecting plate 14 is extremely short. In FIG. 13, only one of the four piles 11 is shown, and the remaining three piles 11 are not shown.

  In this pier foundation structure, the four piles 11 are arranged, for example, at the positions of square apexes. That is, the axis Lb of the four piles 11 is located at the apex of the square in the cross section perpendicular to the axis Lb. The axis La of the steel pipe column 2 is located at the center of the axis Lb of the four piles 11 having a circular tube with the same diameter. The difference between the coupling portion 20E of the present embodiment and the above embodiment is that the steel pipe columns 2 overlap the plurality of piles 11 in a plan view (that is, viewed from the direction of the axis La). The four piles 11 are placed closer to each other than in the above embodiment. The distance between the pile 11 and the pile 11 is equal to or less than the diameter of the steel pipe column 2.

  Even in this case, the steel pipe column 2 is within the range of one large virtual circle that circumscribes the outer peripheral surface of the plurality of piles 11. This is the same as the above embodiment.

  As shown in FIG. 13, the pile head portion 11 a of the pile 11 is cut away leaving a peripheral wall portion 11 c (a peripheral wall portion far from the axis La of the steel pipe column 2, a tile wall-shaped peripheral wall portion). . The range in which the notch is formed is, for example, 180 degrees or more around the axis Lb of the pile 11. The range of the notch may be less than 180 degrees with the axis Lb of the pile 11 as the center. A donut-shaped reinforcing plate 36 for stiffening is welded to the boundary at the lower end of the notch. Edges 11d and 11d extending in the vertical direction formed at both ends in the circumferential direction of the peripheral wall portion 11c are directly joined to the steel pipe column 2 by welding or the like. In addition, the pile 11 may be joined to the steel pipe column 2 by a known steel pipe joint or the like. Concretes 17 and 7 are placed in the space surrounded by the peripheral wall portion 11 c of the pile 11 and the steel pipe column 2 (inside the pile 11) and the steel pipe column 2. As shown in FIG. 12, a reinforcing restraining member 37 that restrains the lower end 2 a of the steel pipe column 2 and the entire pile head 11 a of the four piles 11 may be provided.

  As described above, the lower end portion 2 a of the steel pipe column 2 is fitted into the notches of the four piles and is surrounded by the peripheral wall portions 11 c of the four piles 11. Notched edges 11 d and 11 d of each pile head 11 a of the four piles 11 are coupled to the lower end 2 a of one steel pipe column 2.

  Also by the pier foundation structure according to another embodiment, the same operation and effect as the above embodiment are exhibited. In addition, since the steel pipe column 2 is provided so as to overlap the pile 11 and the steel pipe column 2 is fitted into the notch of the pile 11, it is easy to correspond to the diameter of the steel pipe column 2. For example, even when the diameter of the pile 11 is limited, a pier foundation structure having sufficient strength and rigidity can be realized by adjusting the number of the piles 11, the interval between the piles 11, the range where the notches are formed, and the like. .

  Since one steel pipe column 2 is provided so that its axis La is located at the center of the axis Lb of the plurality of piles 11, the combined state of the steel tube columns 2 with respect to the respective piles 11 can be made uniform. Thereby, it is easy to ensure strength and rigidity.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to the said embodiment.

  For example, it is not restricted to the case where the same pier foundation structure is provided with respect to each steel pipe pillar 2. As shown in FIG. Of the plurality of steel pipe columns 2 of the pier 1, the pier foundation structure of the present invention may be provided for at least one steel pipe column 2. When the pier foundation structure of the present invention is provided for a plurality of steel pipe columns 2, different forms of pier foundation structures may be applied to one steel pipe column 2 and another steel pipe column 2. For example, the direction (direction of a connection part) in which the some pile 11 is arranged may differ with the steel pipe pillar 2, and the number of the piles 11 may differ.

  The connector 12 including the socket 13 is not limited to a method of press-fitting using the pile 11 as a guide. A plurality of piles 11 may be driven simultaneously with respect to the pile 11 and the connector 12 that have been previously installed and fixed at predetermined positions. What is necessary is to provide a shear key that does not move in the axial direction of the pile 11 while providing at least some clearance (gap) between the inner surface of the socket 13 and the pile 11. And if the several pile 11 attached to the coupling tool 12 is driven in order little by little, it is not necessary to press-fit the coupling tool 12 behind.

  For example, when a rotating method of a winged steel pipe pile is adopted, the steel pipe pile can be rotated around the axis in the socket 13 but cannot be moved in the axial direction, and is attached to the connector 12. If the piles 11 are driven by simultaneously press-fitting a plurality of piles 11, the connector 12 can be press-fitted at the same time.

  DESCRIPTION OF SYMBOLS 1 ... Bridge pier, 2 ... Steel pipe pillar (column), 3 ... Horizontal connecting material 10, 10C ... Bridge pier foundation structure, 11 ... Pile, 11a ... Pile head, 11b ... General part, 12, 12A, 12B, 12C ... Connection Tool, 13 ... Socket, 14 ... Connecting plate, 20, 20A, 20B, 20D, 20E ... Coupling part, 30 ... Connector, D ... Flow direction, La ... (Pole) axis, Lb ... (Pile) axis Heart, X ... ground.

Claims (7)

A pier foundation structure that supports a pier having a plurality of columns erected on the ground,
A plurality of piles provided for one of the plurality of pillars and spaced horizontally;
Provided in the ground, and comprising at least one connector for connecting the plurality of piles,
A pier foundation structure, wherein a lower end portion of the one pillar is coupled to pile heads of the plurality of piles. The connector is
A connecting portion extending between the plurality of piles;
The pier foundation structure according to claim 1, further comprising: a plurality of engaging portions that are provided at end portions in the extending direction of the connecting portions and engage with the plurality of piles. The plurality of piles have a circular tube with the same diameter,
3. The pier foundation according to claim 1, wherein the one column is provided such that an axis of the one column is positioned at a center of an axis of the plurality of piles. Construction. The plurality of piles are two piles,
The pier foundation structure according to any one of claims 1 to 3, wherein the two piles are arranged so as to sandwich a diameter of the one pillar. The plurality of piles is three or more piles,
The pier foundation structure according to any one of claims 1 to 3, wherein the three or more piles are arranged at positions of apexes of a regular polygon. The ground has a flow direction in lateral flow accompanying liquefaction during an earthquake,
The pier foundation structure according to any one of claims 1 to 5, wherein any two of the plurality of piles connected by the connector are arranged in the flow direction. . The ground has a flow direction in lateral flow accompanying liquefaction during an earthquake,
The plurality of connectors are provided for the plurality of piles, and the number of the connectors provided along the flow direction is the largest among the plurality of connectors. The pier foundation structure as described in any one of -6.

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