JP7531181B2 - Pile foundation - Google Patents

Description

The present invention relates to pile foundations and base members.

Pile foundations are one type of foundation for erecting a structure on the ground. A pile foundation is a foundation in which piles are driven into the ground to support a structure. One foundation construction method that uses pile foundations is the pin foundation method. With the pin foundation method, steel pipes (pins) are driven diagonally into the ground, and the bearing force of these pipes supports the structure.

Patent Document 1 discloses a support for construction work that is fixed by welding three steel pipes to a central vertical pipe. Anchor pipes serving as piles are inserted into the three steel pipes. Patent Document 2 discloses a base member for pile foundations that is a molded product through which multiple piles are inserted. The base member is installed on the ground surface, and after the piles and supports are inserted, the supports are fixed to the base member.

Special Publication No. 2003-526747 JP 2017-206816 A

Patent Document 2 does not disclose how to fix the pile to the guide section after inserting it into the guide section. When the inventors actually carried out construction using a base member such as that described in Patent Document 2, they found that when the structure supported by the base member is blown by strong winds or the like, and a vertical upward force is applied to the pile via the structure and the base member, the pile may move slightly upward in the vertical direction (i.e., move slightly in the direction of coming out). If such movement of the pile occurs, the bearing capacity of the pile foundation may decrease over time, which may have an adverse effect on the durability life of the pile foundation.

This problem is particularly pronounced when the structure is relatively light (for example, the solar panel mounting frame shown in FIG. 4 of Patent Document 2). When the structure is light, the force acting vertically upwards tends to be greater than the structure's own weight, so the piles are easily moved vertically upwards. Also, when the structure is relatively heavy, even if the piles move vertically upwards, there is a possibility that the piles will automatically return to their original position due to the structure's own weight, but when the structure is light, the effect of the piles returning due to the structure's own weight is reduced.

For this reason, the inventors came to the realization that it was necessary to fix the pile to the base member. For example, Patent Document 1 discloses a technique in which an anchor pipe serving as a pile is inserted into a steel pipe, and then the pile is fixed to the steel pipe using adhesive, a self-tapping screw, a screw, or a collar to prevent it from coming loose (paragraph 0016).

However, adhesives have a relatively low fixing strength, and self-tapping screws must be tightened while carving the threads, so they cannot be used when the base member or pile is made of high-strength materials such as steel pipes. When screws are used, it is necessary to provide screw holes for inserting the screws in both the base member and the pile, and when inserting the pile into the base member, it is necessary to adjust the circumferential angle of the pile so that both screw holes are connected. For this reason, using screws to fix the pile to the base member significantly increases the workload during construction.

In addition, when fixing a pile to a base member with a collar, for example, the collar is attached to the part of the pile that protrudes vertically downward beyond the guide part of the base member, but this part is underground (see Figure 6 (e) of Patent Document 2), and in order to attach the collar to this part, this part needs to be excavated. For this reason, adopting a method of fixing a pile to a base member with a collar significantly increases the workload during construction. As described above, although Patent Document 1 discloses technology for fixing a pile to a steel pipe, none of the methods can be used in actual construction.

The present invention aims to provide a pile foundation and base member that can secure the pile and base member while minimizing the increase in the workload during construction.

(1) The pile foundation of the present invention comprises a base member integrated with a central tube portion and a number of guide tube portions each in a twisted positional relationship with respect to the central tube portion, a support that can be inserted into the central tube portion, a number of piles that can be inserted into the guide tube portions, respectively, and wedges that fix the piles to the guide tube portions, and the guide tube portions are formed with a through hole that extends in the axial direction of the guide tube portion and into which the pile is inserted, and a wedge hole that extends in the tangential direction of the guide tube portion and crosses the side of the through hole, and the wedge inserted into the wedge hole presses against the outer peripheral surface of the pile, thereby fixing the pile to the guide tube portion.

According to the pile foundation of the present invention, the pile is fixed to the guide tube portion by the wedge pressing against the outer peripheral surface of the pile. This eliminates the need to provide screw holes in the pile as is the case when screws are used, and eliminates the need to adjust the circumferential angle of the pile. The only additional work required is to insert the wedge into the wedge hole, so the pile and base member can be fixed together while minimizing the increase in the workload during construction.

(2) Preferably, the guide tube portion has a protrusion that protrudes radially outward from the guide tube portion, the wedge hole is formed radially inward from the protrusion, and when viewed in the tangential direction, the radially outer end of the wedge hole is located at the same position as the outer peripheral surface of the guide tube portion or radially outward from the outer peripheral surface of the guide tube portion, and the radially inner end of the wedge hole is located radially inward from the inner peripheral surface of the guide tube portion.

By configuring it in this way, if a protrusion is provided in the portion of the guide tube where the wedge hole is provided, there is no need to increase the tube thickness in other portions. Therefore, even when a wedge hole is provided, it is possible to suppress the increase in the amount of material required to mold the guide tube.

(3) Preferably, the wedge has a main body extending in the tangential direction, and a leading end protrusion and a trailing end protrusion that protrude radially outward from the main body on one side and the other side of the tangential direction and engage with the protrusions, and the angle at which the leading end protrusion protrudes radially outward from the main body is greater than 90 degrees.

By configuring it in this way, the wedge can be easily removed from the wedge hole by striking the tip protrusion from the front end to the rear end in the insertion direction, making it easier to dismantle the pile foundation.

(4) Preferably, the wedge hole extends in a direction perpendicular to the through hole. By configuring it in this way, the wedge can be driven in a direction perpendicular to the pile, and the pile and the base member can be more firmly fixed.

(5) The base member of the present invention is a base member used as a part of a pile foundation, and includes a central tube portion into which a support pillar is inserted, and guide tube portions that are integrated with the central tube portion and into which multiple piles are inserted, the multiple guide tube portions are each in a twisted positional relationship with respect to the central tube portion, the guide tube portion is formed with a through hole that extends in the axial direction of the guide tube portion and into which the pile is inserted, and a wedge hole that extends in the tangential direction of the guide tube portion and crosses the side end of the through hole, and the pile is fixed to the guide tube portion by a wedge inserted into the wedge hole pressing against the outer peripheral surface of the pile.

According to the base member of the present invention, the wedge inserted into the wedge hole presses against the outer peripheral surface of the pile, thereby fixing the pile to the guide tube portion. This eliminates the need to provide screw holes in the pile as is the case when screws are used, and eliminates the need to adjust the circumferential angle of the pile. The only additional work required is to insert the wedge into the wedge hole, so the pile and base member can be fixed while minimizing the increase in the workload during construction.

The present invention makes it possible to provide a pile foundation and base member that can secure the pile and base member while minimizing the increase in the workload during construction.

FIG. 2 is a front view showing the pile foundation according to the embodiment. FIG. 2 is a perspective view of the base member according to the embodiment, viewed diagonally downward from above. 3 is a front view showing the base member as viewed in the direction of arrow III in FIG. 2 . 4 is a plan view showing the base member as viewed from the direction of arrow IV in FIG. 2 . FIG. 6A and 6B are diagrams illustrating a wedge hole in a base member according to the embodiment. 11A to 11C are diagrams illustrating a wedge according to an embodiment and a modified example. FIG. 2 is a diagram illustrating a construction method for a pile foundation according to an embodiment. 11A and 11B are diagrams illustrating a state in which a wedge is inserted into a wedge hole according to the embodiment.

[Embodiment]
Hereinafter, a pile foundation 1 and a base member 2 according to an embodiment of the present invention will be described. There is no particular limitation on the structure supported by the pile foundation 1. Examples of the structure include a solar panel stand, a street lamp, a road sign, a traffic signal, a signboard, and the like.

[Pile foundation configuration]
1 is a front view showing a pile foundation 1. The pile foundation 1 includes a base member 2, a support column 3, a plurality of piles 4, and a plurality of wedges 5. The pile foundation 1 supports a structure on the upper part of the support column 3 with the support column 3, the plurality of piles 4, and the plurality of wedges 5 inserted into the base member 2.

Figure 2 is a perspective view of the base member 2 as viewed from diagonally above. Figure 3 is a front view of the base member 2 as viewed from the direction of arrow III in Figure 2. Figure 4 is a plan view of the base member 2 as viewed from the direction of arrow IV in Figure 2.

See Figures 2, 3, and 4. The base member 2 is an integrated member of a central tube portion 21 and multiple guide tube portions 22a, 22b, 22c, and 22d, each of which is in a twisted positional relationship with respect to the central tube portion 21. When no particular distinction is made between the guide tube portions 22a, 22b, 22c, and 22d, they are simply referred to as "guide tube portions 22." In this embodiment, there are four guide tube portions 22 and four stakes 4, but the present invention is not limited to this and may have, for example, two or three, or five or more.

The central tube portion 21 and the guide tube portion 22 are each a tube having a hollow interior. In this embodiment, the cross-sectional shape of the tubes of the central tube portion 21 and the guide tube portion 22 is circular, but it may be polygonal or elliptical. The cross-sectional shapes of the tubes of the central tube portion 21 and the guide tube portion 22 correspond to the cross-sectional shapes of the support pillar 3 and the pile 4. The central tube portion 21 is located in the center of the base member 2. The axis of the central tube portion 21 coincides with the center line C1 of the base member 2.

The guide tube portion 22 is formed with a through hole 221 and a wedge hole 222. The through hole 221 is a hole that extends in the axial direction of the guide tube portion 22, and is a hole into which the pile 4 is inserted. The wedge hole 222 will be described later.

The guide tube portions 22 are arranged at equal intervals along the circumferential direction of the central tube portion 21 (i.e., the circumferential direction of the center line C1). In this embodiment, the guide tube portions 22 are arranged at 90 degree intervals. The axis of the guide tube portion 22 is in a twisted positional relationship with respect to the axis of the central tube portion 21. In addition, the axis of the guide tube portion 22 is also in a twisted positional relationship with respect to the axis of the other guide tube portions 22 adjacent to the central tube portion 21 in the circumferential direction.

Specifically, the axis A1 of the guide tube portion 22a is in a twisted positional relationship with the axis A2 of the circumferentially adjacent guide tube portion 22b, the axis A2 of the guide tube portion 22b is in a twisted positional relationship with the axis A3 of the circumferentially adjacent guide tube portion 22c, the axis A3 of the guide tube portion 22c is in a twisted positional relationship with the axis A4 of the circumferentially adjacent guide tube portion 22d, and the axis A4 of the guide tube portion 22d is in a twisted positional relationship with the axis A1 of the circumferentially adjacent guide tube portion 22a. That is, the four guide tube portions 22 are arranged along the circumferential direction of the central tube portion 21 so as to be in a twisted positional relationship with each other.

The central tube portion 21 and the guide tube portion 22a are integrated by being connected at a connecting portion 23a extending in the direction of the axis A1. In other words, the positional relationship between the central tube portion 21 and the guide tube portion 22a is fixed by the connecting portion 23a. Similarly, the central tube portion 21 and the guide tube portions 22b, 22c, and 22d are integrated by being connected at connecting portions 23b, 23c, and 23d extending in the directions of the axes A2, A3, and A4, respectively. When no distinction is made between the connecting portions 23a, 23b, 23c, and 23d, they will be simply referred to as "connecting portions 23." In this embodiment, each connecting portion 23 is connected at the outer circumferential surface of the central tube portion 21.

The base member 2 in this embodiment is cast steel in which the central tube portion 21 and the multiple guide tube portions 22 are integrally formed by casting. In other words, the base member 2 is a single member. In this way, by using a single member for the base member 2, the strength of the base member 2 can be improved compared to when the central tube portion 21 and the multiple guide tube portions 22 are joined as separate independent members. In addition, since it is formed by casting, it can be easily formed even into complex shapes.

The central tube portion 21 has ends 211, 212 in the axial direction. When the base member 2 is installed on the ground surface, the end 211 is located vertically at the top, and the end 212 is located vertically at the bottom. The end 211 is open upward, and the support 3 can be inserted from the end 211. In this embodiment, the end 212 is open downward, and the central tube portion 21 is a tube that opens upward and downward. However, the end 212 may be closed by the bottom surface. Hereinafter, the end 211 will be referred to as the "upper end 211" and the end 212 will be referred to as the "lower end 212".

A pair of through holes 213 and a pair of through holes 214 that penetrate the central tube portion 21 in the radial direction are formed in the peripheral wall of the central tube portion 21 where the connecting portion 23 is not formed. The pair of through holes 213 are formed between the connecting portion 23 and the upper end 211. The pair of through holes 214 are formed between the connecting portion 23 and the pair of through holes 213.

The pair of through holes 213 are arranged at positions facing each other across the center line C1. The pair of through holes 214 are arranged in the same manner. The diameter of the through holes 213 and 214 is, for example, 15 mm. The through holes 213 and 214 function as drill guide holes for guiding an electric drill when drilling the support 3 inserted into the central tube portion 21. The through holes 213 and 214 also function as bolt guide holes for inserting a bolt from the outer periphery of the central tube portion 21. After inserting the support 3 into the central tube portion 21 and drilling the support 3 through the through holes 213 with an electric drill, the bolt is inserted from one of the through holes 213 and protrudes from the other through hole 213, and is fastened with a nut to fix the base member 2 and the support 3.

In this embodiment, through holes 213 are formed directly above through holes 214. However, through holes 213 may be positioned in a location other than directly above through holes 214. For example, a pair of through holes 213 may be formed above connecting portions 23b and 23d, and a pair of through holes 214 may be formed above connecting portions 23a and 23c. In other words, through holes 213 and through holes 214 may be positioned at angles different from each other by 90 degrees.

See FIG. 1. The support pillar 3 is, for example, a metal pipe, for example, a steel pipe. A mounting fixture (not shown) is provided above the support pillar 3 to connect the support pillar 3 to a structure. The diameter of the support pillar 3 is, for example, 80 mm to 100 mm.

The pillar 3 has a wall thickness that can be drilled with a drill inserted into the through hole 213 or the through hole 214. Here, "wall thickness that can be drilled with a drill" means a wall thickness that can be drilled with a handheld electric drill by a worker at the foundation construction site within 30 seconds, preferably within 10 seconds. Specifically, in the case of a steel pipe, the wall thickness is 5 mm or less, for example, 3 mm to 4 mm. The wall thickness of the pillar 3 is selected appropriately depending on the drilling time with the drill and the strength required for the pillar 3.

The pillars 3 also have a thickness and diameter that can be cut by a cutter. Specifically, this means a thickness that can be cut by a handheld electric cutting tool (e.g., an electric cutter, an electric saw, etc.) by a worker at the foundation construction site within 5 minutes, preferably within 1 minute.

Before being drilled, the support 3 is inserted into the hollow part of the central tube 21. The support 3 is located in the center of the central tube 21, and the axis of the support 3 coincides with the axis of the central tube 21. In other words, the axis of the support 3 coincides with the center line C1 of the base member 2. The outer diameter of the support 3 is equal to the inner diameter of the central tube 21 (or slightly smaller than the inner diameter of the central tube 21), and when the support 3 is inserted into the central tube 21, the outer surface of the support 3 and the inner surface of the central tube 21 come into contact. At this time, the through holes 213 and 214 are blocked by the support 3 on the inner surface side of the central tube 21.

The pile 4 is, for example, a metal pipe, specifically a steel pipe. The diameter of the pile 4 is, for example, 40 mm to 60 mm, and preferably 48.6 mm. The thickness of the pile 4 is, for example, 2 mm to 4 mm, and preferably 3 mm. The four piles 4 are inserted into the four guide tubes 22, respectively. The outer diameter of the pile 4 is equal to the inner diameter of the guide tube 22 (i.e., the diameter of the through hole 221) (or slightly smaller than the inner diameter of the guide tube 22), and when the pile 4 is inserted into the guide tube 22, the outer surface of the pile 4 and the inner surface of the guide tube 22 are in contact with each other. In this way, by contacting the inner surface of the guide tube 22, the penetration angle of the pile 4 into the ground is fixed by the guide tube 22.

Since the guide tube portions 22 are in a twisted positional relationship, the piles 4 that are driven into the ground via the guide tube portions 22 are also in a twisted positional relationship. The piles 4 are also positioned at 90 degree intervals, just like the guide tube portions 22. Therefore, the base member 2 is supported in a well-balanced manner by the piles 4 that are guided into the ground by the guide tube portions 22.

Figure 5 is a diagram illustrating the wedge hole 222 of the guide tube portion 22. In Figure 5, the wedge hole 222 of the guide tube portion 22a is representatively described, but the wedge holes 222 of the other guide tube portions 22b, 22c, and 22d also have the same structure as in Figure 5. Figure 5(a) is a partially enlarged view of a cross section taken along the cutting line indicated by arrow V in Figure 3. The cutting line indicated by arrow V is a line that passes through the center of the wedge hole 222 in the axial center A1 direction in Figure 3 and is perpendicular to the axial center A1. Figure 5(a) shows an enlarged view of the radially outer portion of the guide tube portion 22.

The guide tube portion 22 has a cylindrical shape including an inner peripheral surface 220a and an outer peripheral surface 220b. The through hole 221 is formed as a space surrounded by the inner peripheral surface 220a. The guide tube portion 22 has a protruding portion 223 that protrudes radially outward, and the wedge hole 222 is formed radially inward of this protruding portion 223.

The wedge hole 222 extends in the tangential direction B1 of the guide tube portion 22 (more specifically, in the tangential direction B1 of the inner peripheral surface 220a of the guide tube portion 22) and crosses the side portion 221a of the through hole 221. That is, the wedge hole 222 is a hole that connects from the outer peripheral surface 220b to the inner peripheral surface 220a of the guide tube portion 22, skims the side portion 221a of the through hole 221, and reaches the outer peripheral surface 220a on the other side from the inner peripheral surface 220a to the outer peripheral surface 220b. In other words, the wedge hole 222 and the through hole 221 overlap at the side portion 221a.

In this embodiment, the wedge hole 222 extends in a direction perpendicular to the through hole 221. That is, when the tangential direction B1 is slid parallel to the radial inside of the guide tube portion 22 so as to intersect with the axis A1, the tangential direction B1 and the axis A1 after sliding are perpendicular to each other. Note that the wedge hole 222 only needs to extend in a direction intersecting the through hole 221, and does not necessarily need to extend in a perpendicular direction.

5(b) is a cross-sectional view taken along the cutting line indicated by the arrow Vb in FIG. 5(a). The cutting line indicated by the arrow Vb is a line perpendicular to the tangential direction B1 and passing through the axis A1. FIG. 5(b) is also a view of the wedge hole 222 seen in the tangential direction B1. The left-right direction in FIG. 5(b) corresponds to the radial direction of the guide tube portion 22, with the left side of FIG. 5(a) being the radially inner side and the right side being the radially outer side. The radially outer end 222a of the wedge hole 222 is inside the protrusion 223 and is at the same position as the outer peripheral surface 220b of the guide tube portion 22. The end 222a may be located radially outer than the outer peripheral surface 220b. The radially inner end 222b of the wedge hole 222 is located radially inner than the inner peripheral surface 220a of the guide tube portion 22. The tube thickness d1 at a position other than the protruding portion 223 of the guide tube portion 22 is, for example, 6 mm. The radial thickness d2 of the protruding portion 223 of the guide tube portion 22 is, for example, 8 mm, which is thicker than the tube thickness d1.

Figure 5 (c) is a diagram showing the state in which the pile 4 is inserted into the guide tube portion 22 in the same cross section as Figure 5 (a). In this embodiment, the pile 4 has a cylindrical shape including an inner peripheral surface 4a and an outer peripheral surface 4b. In other words, the pile 4 has a hollow structure. The pile 4 may also have a cylindrical shape with a solid structure. The outer peripheral surface 4b of the pile 4 inserted into the through hole 221 of the guide tube portion 22 is in contact with the inner peripheral surface 220a of the guide tube portion 22. In this state, a part of the pile 4 is located on the side portion 221a of the through hole 221. Therefore, the outer peripheral surface 4b of the pile 4 is exposed so as to be embedded in the wedge hole 222.

Figure 5(d) is a diagram showing the state in which the pile 4 is inserted into the guide tube portion 22 in the same cross section as Figure 5(b). The outer peripheral surface 4b of the inserted pile 4 is located radially outward from the end 222b of the wedge hole 222 and radially inward from the end 222a.

Figure 5(e) is a diagram showing the same cross section as Figure 5(b) in which the pile 4 is inserted into the guide tube portion 22 and then the wedge 5 is inserted in the tangential direction B1. The inserted wedge 5 presses against the outer peripheral surface 4b of the pile 4, deforming a portion of the pile 4 so that it is recessed radially inward. The pile 4 is firmly fixed to the guide tube portion 22 by the wedge 5 pressing against the pile 4 radially inward and the wedge 5 and the pile 4 fitting together in the direction of the axis A1 due to the deformation of the pile 4. Note that it is not essential that the wedge 5 deforms the pile 4, and the pile 4 may be fixed to the guide tube portion 22 only by the wedge 5 pressing against the outer peripheral surface 4b of the pile 4.

Figure 6 is a diagram explaining the structure of the wedge. Figure 6 (a) is a perspective view of the wedge 5 according to the embodiment. Figure 6 (b) is a side view of the wedge 5. The insertion direction of the wedge 5 coincides with the tangential direction B1 (i.e., the direction in which the wedge hole 222 extends). In Figure 6 (b), the wedge 5 is in the same position as when it is inserted into the wedge hole 222, and the left-right direction in Figure 6 (b) corresponds to the tangential direction B1, and the up-down direction corresponds to the radial direction of the guide tube portion 22. The right side of Figure 6 (b) is one side of the tangential direction B1, the left side is the other side of the tangential direction B1, the lower side is the radial inner side, and the upper side is the radial outer side. The wedge 5 is inserted into the wedge hole 222 from the other side of the tangential direction B1 to one side. Therefore, one side of the tangential direction B1 is the leading end side of the wedge 5 in the insertion direction, and the other side of the tangential direction B1 is the trailing end side of the wedge 5 in the insertion direction.

6(a) and (b). The wedge 5 has a main body 51, a tip protrusion 52, and a rear end protrusion 53. The main body 51 is a portion extending in the tangential direction B1. The main body 51 has a first surface 51a on the radially inner side and a second surface 51b on the radially outer side. As shown in FIG. 5(e), the first surface 51a is a surface (pressing surface) that presses the outer peripheral surface 4b of the pile 4 after insertion into the wedge hole 222. The first surface 51a has a taper that inclines radially outward as it approaches one side of the tangential direction B1. As shown in FIG. 5(e), the second surface 51b is a surface located on the end 222a side of the wedge hole 222 after insertion into the wedge hole 222. The second surface 51b extends in a direction along the tangential direction B1. For this reason, the main body 51 has a shape in which the radial width becomes narrower toward one side of the tangential direction B1.

The tip protrusion 52 is a portion that protrudes radially outward from the main body 51 on one side of the tangential direction B1. The tip protrusion 52 has a tapered surface 55 and an outer surface 56. The outer surface 56 extends in a direction along the tangential direction B1. In other words, the outer surface 56 is parallel to the second surface 51b.

The tapered surface 55 is connected to one side of the second surface 51b in the tangential direction B1 and to the other side of the outer surface 56 in the tangential direction B1. That is, the tapered surface 55 is located between the second surface 51b and the outer surface 56 in the tangential direction B1. The tapered surface 55 has a taper that slopes radially outward as it approaches one side of the tangential direction B1, and the angle θ1 that the tapered surface 55 and the second surface 51b make radially outward is 135 degrees. The angle θ1 can also be said to be the angle at which the tip protrusion 52 protrudes radially outward from the main body 51. Note that the angle θ1 may be any angle greater than 90 degrees and less than 180 degrees.

A concave surface 54 is formed in an area of the first surface 51a located radially inward of the tip protrusion 52. The radius of curvature of the concave surface 54 is half or less the length in the tangential direction B1 of the wedge 5 and is at least twice the length in the tangential direction B1 of the outer surface 56. For example, when the length in the tangential direction B1 of the wedge 5 is 57 mm and the length in the tangential direction B1 of the outer surface 56 is 10 mm, the radius of curvature of the concave surface 54 is 24.5 mm. By configuring in this manner, the concave surface 54 can be formed from the end 54a on one side of the tangential direction B1 of the wedge 5 to the portion 54b on the first surface 51a.

The concave surface 54 is recessed from the first surface 51a by a distance greater than the width of the tip projection 52 projecting radially outward from the main body 51. That is, the length from the portion 54b to the end 54a of the concave surface 54 is longer than the sum of the lengths of the tapered surface 55 and the outer surface 56 in the tangential direction B1. Therefore, even though the tip projection 52 projects from the main body 51, the wedge 5 has a tapered shape toward one side in the tangential direction B1. By configuring it in this way, as described later, it becomes easier to remove the wedge 5 from the wedge hole 222 after it has been inserted into the wedge hole 222. The radius of curvature of the concave surface 54 is approximately the same as the radius (24.3 mm) of the outer peripheral surface 4b of the pile 4.

6(c) is a side view of a wedge 50 according to a modified example. The shape of the tip protrusion 520 of the wedge 50 is different from that of the tip protrusion 52 of the wedge 5, and the other parts are common to the wedge 5. The common parts are given the same reference numerals as the wedge 5, and the description is omitted. The tip protrusion 520 has a vertical surface 550 and an outer surface 560. The outer surface 560 has a taper that inclines radially inward as it approaches one side of the tangential direction B1. The vertical surface 550 connects to one side of the tangential direction B1 of the second surface 51b, and connects to the other side of the tangential direction B1 of the outer surface 560. The vertical surface 550 extends in a radial direction, and the angle θ2 that the vertical surface 550 and the second surface 51b make radially outward is 90 degrees. The wedge 50 has a sharper angle θ2 at which the tip protrusion protrudes than the wedge 5. This configuration makes it difficult for the wedge 50 to slip out of the wedge hole 222 after it has been inserted into the wedge hole 222.

The decision as to whether to use wedge 5 or wedge 50 is made taking into consideration the strength, durability, and dismantling method required for pile foundation 1. Either wedge 5 or wedge 50 can be used to fix pile 4 to guide tube portion 22, but if there are plans to dismantle pile foundation 1 relatively early (e.g., before pile foundation 1 deteriorates to a certain extent), it is preferable to use wedge 5, which can be easily removed from wedge hole 222.

[Pile foundation construction method]
7 is a diagram illustrating a construction method for the pile foundation 1 according to the embodiment. The pile foundation 1 is constructed by a worker performing the construction method described below.

First, as shown in FIG. 7(a), a worker places the base member 2 on the ground G1 with the axis of the central tube portion 21 aligned vertically. The ground G1 may be a surface that is recessed from the ground surface by a worker digging the ground surface with a handheld shovel to the extent that the base member 2 is buried. The central tube portion 21 is placed on the ground G1 with the upper end 211 facing vertically upward and the lower end 212 facing vertically downward, with the lower end 212 in contact with the ground G1. The base member 2 is manually carried by a worker and placed on the ground G1.

Next, as shown in FIG. 7(b), the worker drives the four piles 4 into the ground via the four guide tubes 22. The piles 4 are inserted into the through holes 221 (FIG. 3) of the guide tubes 22. The worker drives the piles 4 into the ground by striking the top ends of the piles 4 with an electric tool such as a handheld electric hammer.

The piles 4 are driven into the ground G1 along the axes A1, A2, A3, and A4, which are in a twisted relationship with each other, so that the base member 2 is supported by the piles 4 from the axes A1, A2, A3, and A4. As a result, the base member 2 is fixed to the ground G1 by the piles 4, and the base member 2 can be prevented from moving in the horizontal and vertical directions. This ensures sufficient support force for erecting the support pillars 3, which will be inserted into the base member 2 in the next process.

Next, the worker cuts the support 3 radially with a handheld electric cutter to adjust the axial length of the support 3, and then inserts the support 3 into the central tube portion 21. Because the outer diameter of the support 3 is equal to the inner diameter of the central tube portion 21, the support 3 is inserted into the central tube portion 21 while the outer peripheral surface of the support 3 and the inner peripheral surface of the central tube portion 21 are in sliding contact with each other.

Also, as shown in FIG. 7(c), a worker uses a hand hammer to insert the wedge 5 into the wedge hole 222 of the guide tube portion 22. The inserted wedge 5 presses against the outer peripheral surface 4b of the pile 4, thereby fixing the pile 4 to the guide tube portion 22. The order of inserting the wedge 5 into the wedge hole 222 may be before or after the insertion into the central tube portion 21 of the support 3.

Figure 8 is a diagram illustrating how the wedge 5 is inserted into the wedge hole 222 in the same cross section as Figure 5(c). Figure 8(a) shows the state when the wedge 5 starts to be inserted, Figures 8(b) and (c) show the state when the wedge 5 is being inserted, respectively, and Figure 8(d) shows the state when the wedge 5 has been inserted.

The radius of curvature (24.5 mm) of the concave surface 54 of the wedge 5 is approximately the same as the radius (24.3 mm) of the outer peripheral surface 4b of the pile 4 (for example, the difference between the two values is within 1 mm), so as shown in FIG. 8(a), when the wedge 5 begins to be inserted, the concave surface 54 follows the outer peripheral surface 4b. Therefore, when the worker manually inserts the wedge 5 into the wedge hole 222, the wedge 5 is stably held between the outer peripheral surface 4b and the protrusion 223 with the concave surface 54 following the outer peripheral surface 4b. This makes it easier for the worker to aim when driving the wedge 5 with a hammer.

See Figures 8(b) and (c). The worker hits the rear end of the wedge 5 with a hammer, inserting the wedge 5 into the wedge hole 222. At this time, the pile 4 is deformed radially inward by being pressed against the first surface 51a including the concave curved surface 54 of the wedge 5. Finally, as shown in Figure 8(d), the tapered surface 55 of the wedge 5 is inserted to a position on one side of the protruding portion 223 in the tangential direction B1, and the rear end protrusion 53 engages with the other side of the protruding portion 223 in the tangential direction B1, completing the insertion of the wedge 5.

The wedge 5 presses against the outer peripheral surface 4b of the pile 4, and is pressed from the outer peripheral surface 4b of the pile 4 toward the protruding portion 223. The wedge 5 is sandwiched between the protruding portion 223 and the outer peripheral surface 4b, so that the wedge 5 is prevented from slipping out of the wedge hole 222. In addition, as shown in FIG. 6, there is a predetermined angle θ1 between the main body 51 and the tip protruding portion 52, so that even if the wedge 5 slips out slightly in the tangential direction B1 due to an external force acting on the pile foundation 1, the tip protruding portion 52 engages with one side of the protruding portion 223, and the wedge 5 can be reliably prevented from slipping out naturally.

Refer to FIG. 7(d). Next, the worker inserts a hand-held electric drill radially through the through holes 213 to drill holes in the peripheral surface of the support 3. Similarly, the worker inserts an electric drill radially through the through holes 214 to drill holes in the peripheral surface of the support 3. In this embodiment, the support 3 is drilled at two locations for each pair of through holes 213 and pair of through holes 214. As a result, four holes are formed in the support 3.

Finally, the worker inserts the bolt 6 from one of the through holes 213, and causes the end of the bolt 6 to protrude from the other through hole 213. Then, a nut is fastened to the protruding bolt 6. Similarly, the bolt 6 is inserted from one of the through holes 214, and causes the end of the bolt 6 to protrude from the other through hole 214, and a nut is fastened to the protruding bolt 6. In this way, the support 3 is fixed to the central tube portion 21. Here, the diameter of the bolt 6 is smaller than the diameters of the through holes 213 and 214, and is, for example, 12 mm. Furthermore, the length of the bolt 6 is longer than the outer diameter of the central tube portion 21, and is, for example, 110 mm.

[Actions and Effects of the Embodiments]
As described above, the pile foundation 1 according to the embodiment includes the base member 2 integrated with the central tube portion 21 and the multiple guide tube portions 22 each having a twisted positional relationship with respect to the central tube portion 21, the support 3 insertable into the central tube portion 21, the multiple piles 4 insertable into the multiple guide tube portions 22, and the wedge 5 for fixing the piles 4 to the guide tube portion 22. The guide tube portion 22 is formed with a through hole 221 extending in the axial direction of the guide tube portion 22 and into which the pile 4 is inserted, and a wedge hole 222 extending in the tangential direction B1 of the through hole 221 and crossing the side portion 221a of the through hole 221. The wedge 5 inserted into the wedge hole 222 presses against the outer peripheral surface 4b of the pile 4, thereby fixing the pile 4 to the guide tube portion 22.

According to the pile foundation 1 according to the embodiment, the pile 4 is fixed to the guide tube portion 22 by the wedge 5 pressing against the outer peripheral surface 4b of the pile 4. Therefore, there is no need to provide a screw hole in the pile 4 as in the case of using a screw, and the circumferential angle adjustment of the pile 4 is not required. The only additional work required is to insert the wedge 5 into the wedge hole 222, so the pile 4 and the base member 2 can be fixed together while minimizing the increase in the workload during construction.

In particular, the pile foundation 1 can be constructed entirely with hand-held tools, eliminating the need for large-scale heavy machinery, which helps reduce construction costs. For example, the wedge 5 can be inserted into the wedge hole 222 with a hand-held hammer.

The guide tube portion 22 also has a protrusion 223 that protrudes radially outward, and the wedge hole 222 is formed radially inward of the protrusion 223. When viewed in the tangential direction B1, the radially outer end 222a of the wedge hole 222 is located at the same position as the outer peripheral surface 220b of the guide tube portion 22 or radially outward from the outer peripheral surface 220b, and the radially inner end 222b of the wedge hole 222 is located radially inward from the inner peripheral surface 220a of the guide tube portion 22.

By configuring it in this way, if the protrusion 223 is provided in the portion of the guide tube portion 22 where the wedge hole 222 is provided, there is no need to increase the tube thickness in other portions. Therefore, even when the wedge hole 222 is provided, the increase in the material required to mold the guide tube portion 22 can be suppressed. This makes it possible to suppress the increase in weight of the base member 2, making it easier for workers to carry it manually.

The wedge 5 also has a main body 51 extending in the tangential direction B1, and a leading end protrusion 52 and a trailing end protrusion 53 that protrude radially outward from the main body 51 on one side and the other side of the tangential direction B1 and engage with the protrusion 223. The angle θ1 at which the leading end protrusion 52 protrudes radially outward from the main body 51 is greater than 90 degrees.

Here, after the useful life of the structure supported by the pile foundation 1 has expired, it may become necessary to dismantle the pile foundation 1. For this reason, the pile foundation 1 is also required to be easy to dismantle. In the pile foundation 1 of this embodiment, the angle θ1 at which the tip protrusion 52 protrudes from the main body 51 is greater than 90 degrees, so that after the wedge 5 is inserted, the tip protrusion 52 engages with the protrusion 223, thereby preventing the wedge 5 from coming out. When dismantling the pile foundation 1, the tip protrusion 52 can be driven from one side to the other in the tangential direction B1 to easily remove the wedge 5 from the wedge hole 222.

In addition, since the base member 2 of this embodiment itself is not drilled or deformed during construction, the base member 2 can be reused after the supports 3 and piles 4 are removed. This makes it possible to reduce the amount of waste after the pile foundation 1 is dismantled, compared to the case of a concrete foundation. This makes it possible to reduce dismantling costs, including waste disposal costs.

The wedge hole 222 also extends in a direction perpendicular to the through hole 221. This configuration allows the wedge 5 to be driven in a direction perpendicular to the pile 4, and the pile 4 and the base member 2 can be more firmly fixed together.

[Modifications]
Although the embodiment of the present invention has been described above, the present invention can be modified in various ways in addition to the above-described embodiment. Below, modified examples of the embodiment of the present invention will be described. In the following modified examples, the same components as those in the embodiment will be given the same reference numerals and will not be described.

In the above embodiment, the wedge holes 222 are provided in all of the multiple guide tube portions 22. However, the wedge holes 222 may be provided in at least some of the multiple guide tube portions 22. For example, the wedge holes 222 may be provided in the diagonally positioned guide tube portions 22a and 22c, and the remaining guide tube portions 22b and 22d may not have wedge holes 222. In addition, it is not necessary to insert the wedges 5 into all of the wedge holes 222 provided, and the number of wedges 5 inserted may be adjusted appropriately depending on the required support force, etc.

In addition, multiple wedge holes 222 may be provided in one guide tube portion 22. For example, two wedge holes 222 may be provided spaced apart in the axial direction of the guide tube portion 22. By inserting a wedge 5 into each of these wedge holes 222, the pile 4 can be more firmly fixed to the guide tube portion 22.

〔others〕
In addition, at least a part of the above-mentioned embodiment and various modified examples may be arbitrarily combined with each other. In addition, the embodiment disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present invention is defined by the claims, and it is intended to include all modifications within the meaning and scope of the claims.

REFERENCE SIGNS LIST 1 pile foundation 2 base member 21 central tube portion 211 upper end 212 lower end 213 through hole 214 through hole 22 guide tube portion 220a inner peripheral surface 220b outer peripheral surface 221 through hole 221a side portion 222 wedge hole 222a end 222b end 223 protrusion 23 connecting portion 3 support 4 pile 4a inner peripheral surface 4b outer peripheral surface 5 wedge 50 wedge 51 main body portion 51a first surface 51b second surface 52 tip protrusion portion 53 rear end protrusion portion 54 concave curved surface 54a end 54b portion 55 tapered surface 56 outer surface 520 tip protrusion portion 550 vertical surface 560 outer surface 6 Bolt A1 Axis center B1 Tangent direction θ1 Angle θ2 Angle G1 Ground

Claims (6)

a base member in which a central cylinder portion and a plurality of guide cylinder portions each having a twisted positional relationship with respect to the central cylinder portion are integrated;
A support that can be inserted into the central tube portion;
A plurality of piles that can be inserted into the plurality of guide tube portions, respectively;
A wedge that fixes the pile to the guide tube portion;
Equipped with
The guide tube portion has:
A through hole extending in the axial direction of the guide tube portion and into which the pile is inserted;
a wedge hole extending in a tangential direction of the guide tube portion and crossing a side portion of the through hole is formed;
A pile foundation in which the wedge inserted into the wedge hole presses against the outer peripheral surface of the pile, causing a portion of the pile to deform so as to be concave radially inward, and the pile is fixed to the guide tube portion with the wedge and the pile fitted in the axial direction . The guide tube portion has a protrusion that protrudes radially outward from the guide tube portion,
The wedge hole is formed on the radially inner side of the protrusion,
The pile foundation described in claim 1, wherein, when viewed in the tangential direction, the radially outer end of the wedge hole is located at the same position as the outer peripheral surface of the guide tube portion or radially outer than the outer peripheral surface, and the radially inner end of the wedge hole is located radially inner than the inner peripheral surface of the guide tube portion. Of the first surface on the radially inner side of the wedge that contacts the outer peripheral surface of the pile, a concave curved surface is formed on the tip side where the wedge is inserted,
The concave surface has a radius of curvature substantially equal to the radius of the outer circumferential surface of the pile so that, when the wedge is inserted into the wedge hole, the wedge can be held by the outer circumferential surface of the pile and the protruding portion with the concave surface along the outer circumferential surface of the pile.
The pile foundation according to claim 2. a base member in which a central cylinder portion and a plurality of guide cylinder portions each having a twisted positional relationship with respect to the central cylinder portion are integrated;
A support that can be inserted into the central tube portion;
A plurality of piles that can be inserted into the plurality of guide tube portions, respectively;
A wedge that fixes the pile to the guide tube portion;
Equipped with
The guide tube portion has:
A through hole extending in the axial direction of the guide tube portion and into which the pile is inserted;
a wedge hole extending in a tangential direction of the guide tube portion and crossing a side portion of the through hole is formed,
The wedge inserted into the wedge hole presses the outer circumferential surface of the pile, thereby fixing the pile to the guide tube portion,
The guide tube portion has a protrusion that protrudes radially outward from the guide tube portion,
The wedge hole is formed on the radially inner side of the protrusion,
When viewed in the tangential direction, the radially outer end of the wedge hole is located at the same position as an outer circumferential surface of the guide tube portion or is located radially outer than the outer circumferential surface, and the radially inner end of the wedge hole is located radially inner than an inner circumferential surface of the guide tube portion,
Of the first surface on the radially inner side of the wedge that contacts the outer peripheral surface of the pile, a concave curved surface is formed on the tip side where the wedge is inserted,
The concave surface has a radius of curvature substantially equal to the radius of the outer circumferential surface of the pile so that, when the wedge is inserted into the wedge hole, the wedge can be held by the outer circumferential surface of the pile and the protruding portion with the concave surface along the outer circumferential surface of the pile.
Pile foundation. The wedge is
a body portion extending in the tangential direction;
a front end protrusion and a rear end protrusion protruding from the main body portion on one side and the other side in the tangential direction toward the outside in the radial direction and engaging with the protrusions,
The pile foundation according to claim 2 , wherein an angle at which the tip projection projects radially outward from the main body is greater than 90 degrees. The pile foundation according to claim 1 , wherein the wedge hole extends in a direction perpendicular to the through hole.

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