Pile driving method, and reinforcing body and connecting jig used therefor

Abstract

To provide a pile driving method capable of reinforcing a head of a pile driven into the ground.SOLUTION: This invention is a pile driving method in which a cylindrical reinforcing body 20 that reinforces bearing capacity of a pile (for example, a steel pipe pile 1) driven into the ground 5 is driven into the ground 5 together with the pile using a driving machine 30. The driving method includes a first driving step in which, with a pile head 1a of a steel pipe pile 1 connected to the driving machine 30, the steel pipe pile 1 is driven into the ground 5 from the ground surface by the driving machine 30, leaving the pile head 1a of the steel pipe pile 1, and a second driving step in which, with the pile head 1a inserted into a through-hole 22 formed in the reinforcing body, the reinforcing body 20 is pressed into the ground 5 while driving the pile head 1a.SELECTED DRAWING: Figure 7

Description

[Technical field]

[0001] The present invention relates to a pile driving method for supporting a building or the like, and in particular to a pile driving method for reinforcing the head of a pile driven into the ground, as well as a reinforcing body and a connecting jig used therein. [Background technology]

[0002] Conventionally, this type of pile driving method includes the steps of removing the peripheral area of ​​the buried pile to expose the pile, forming a reinforcing layer at the bottom of the removed area, and attaching a flange member that abuts the reinforcing layer to the exposed pile (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2011-69187 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, the pile driving method described above requires the removal of soil from the pile head, which incurs disposal costs. Also, since the ground around the pile head is backfilled, the horizontal bearing capacity of the pile is insufficient.

[0005] The present invention has been made in consideration of such problems, and provides a pile driving method that can reinforce the head of a pile driven into the ground, as well as a reinforcing body and a connecting jig used therein. [Means for solving the problem]

[0006] In view of the above problems, the pile driving method of the present invention is a pile driving method in which a cylindrical reinforcing body that reinforces the bearing capacity of a pile driven into the ground is driven into the ground together with the pile using a driving machine, and is characterized by including a first driving step in which, with the pile head of the pile connected to the driving machine, the driving machine drives the pile from the ground surface into the ground, leaving the pile head remaining, and a second driving step in which, with the pile head inserted into a through hole formed in the reinforcing body, the reinforcing body is pressed into the ground while driving the pile head.

[0007] According to the present invention, in the first driving step, the pile is driven into the ground from the ground surface by a driving machine, leaving the pile head of the pile. Next, in the second driving step, the reinforcement body is pressed into the ground while driving the pile head with the pile head inserted into the through hole formed in the reinforcement body. As a result, the reinforcement body is arranged around the pile head, so that the soil equivalent to the volume of the reinforcement body can be compressed by the reinforcement body and compacted around the pile head of the pile. As a result, the density of the ground directly below the foundation is increased, which can improve the performance of the vertical bearing capacity and horizontal bearing capacity, and can reduce the vertical and horizontal displacement amounts.

[0008] The reinforcing body used in the pile driving method may be formed on-site, but it is preferable to manufacture it in a factory, for example, since there is less variation in quality compared to when the reinforcing body is formed on-site, and the vertical and horizontal bearing capacity of the pile can be stabilized. In addition, since the pile and the reinforcing body can be driven into the ground at the same time, there is no need to form a recess for embedding the reinforcing body, and the surface layer of the ground will not collapse toward the pile. Furthermore, there is no need to compact the ground around the pile head, which reduces the number of people and labor required for on-site construction and shortens the construction period.

[0009] In a more preferred embodiment, the reinforcing body has a cylindrical main body portion and a tapered truncated cone portion continuing from the circumferential surface of the main body portion, and in the second casting step, the reinforcing body is pressed in with the truncated cone portion facing downward.

[0010] According to this embodiment, the reinforcing body is pressed in with the truncated cone portion facing downward, which not only makes it easier to press the reinforcing body into the ground, but also enables the truncated cone portion to compact the ground around the pile head when the reinforcing body is pressed in.

[0011] Here, when pressing the reinforcing body into the ground, the reinforcing body may be pressed in vertically together with the pile, but in a more preferred embodiment, in the second driving step, the reinforcing body is pressed into the ground while being rotated around the axis of the pile.

[0012] According to this aspect, by pressing the reinforcing body into the ground while rotating it, it becomes easier to press the reinforcing body into the ground compared to the case where the reinforcing body is pushed into the ground from the vertical direction. In particular, when the pile is a steel pipe pile provided with a spiral tip wing or the like, the reinforcing body can be pressed into the ground while rotating together with the pile. In particular, when a spiral wing is formed along the circumferential direction on the conical surface of the truncated cone part of the reinforcing body, this effect can be further enhanced.

[0013] When the reinforcement body is rotated in a direction in which the spiral blade of the reinforcement body pushes the soil in the ground downward, the tip blade formed at the tip of the steel pipe pile can compact the loosened soil in the surface layer of the ground. On the other hand, when the reinforcement body is rotated in a direction in which the spiral blade scoops out the soil in the ground, if the surface layer of the ground is hard, the reinforcement body can be pressed in while scooping out the soil.

[0014] In a further preferred embodiment, the pile head of the pile is connected to the driving machine via a connecting jig, and at least one engagement recess for engaging with the connecting jig is formed on the upper end surface of the reinforcement body along the axis of the reinforcement body, and the connection jig has a connecting portion connected to the driving machine, a plate portion fixed to the lower end of the connecting portion and abutting the upper end surface of the reinforcement body, and an engagement protrusion protruding from the plate portion into the reinforcement body and engaging with each engagement recess formed on the reinforcement body, and in the second driving step, the engagement protrusion of the connecting jig is engaged with the engagement recess of the reinforcement body, and then the reinforcement body is pressed into the ground while rotating around the axis of the pile.

[0015] According to this aspect, after the engaging convex portion of the connecting jig is engaged with the engaging concave portion of the reinforcing body, the reinforcing body can be stably pressed into the ground while being rotated around the axis of the pile.

[0016] In an even more preferred embodiment, a guide tube is formed on the plate portion and is inserted into a gap formed between the outer surface of the pile head and the inner surface of the through hole of the reinforcement body when the pile head is inserted into the reinforcement body, and in the second casting step, the engaging convex portion of the connecting jig is engaged with the engaging concave portion of the reinforcement body and the guide tube of the connecting jig is inserted into the gap, and then the reinforcement body is pressed into the ground while rotating around the axis of the pile.

[0017] According to this aspect, the reinforcing body is pressed into the ground while rotating the reinforcing body around the axis of the pile with the guide tube inserted into the gap formed between the outer peripheral surface of the pile head and the inner peripheral surface of the through hole of the reinforcing body. This makes it possible to accurately drive the pile while guiding the pile along the driving direction (vertical direction) with the guide tube of the connecting jig, while preventing the axis of the reinforcing body from tilting or shifting during the driving. At this time, it is preferable to remove the connecting jig from the reinforcing body after the second driving step, and insert a ring so as to fill the gap into which the guide tube is inserted. This makes it possible to firmly connect the pile and the reinforcing body by inserting the ring, and to improve the vertical and horizontal support forces of the pile. The ring may form a part of the cap.

[0018] The reinforcement body according to the present invention is a reinforcement body used in the pile driving method, and the reinforcement body has a cylindrical main body and a tapered truncated cone portion continuing from the circumferential surface of the main body. According to the present invention, by pressing the reinforcement body into the ground while rotating it, it becomes easier to press the reinforcement body into the ground compared to the case where the reinforcement body is pressed into the ground from the vertical direction.

[0019] The connection jig of the present invention is a connection jig used in the pile driving method, and the connection jig has a connecting portion connected to the driving machine, a plate portion fixed to the lower end of the connecting portion and abutting the upper end surface of the reinforcement body, and an engaging protrusion portion protruding from the plate portion to the reinforcement body and engaging with an engaging recess formed in the reinforcement body.

[0020] According to the present invention, after the engaging convex portion of the connecting jig is engaged with the engaging concave portion of the reinforcing body, the reinforcing body can be stably pressed into the ground while rotating it around the axis of the pile. Effect of the Invention

[0021] According to the pile driving method of the present invention, the vertical bearing capacity and horizontal bearing capacity of the pile can be improved, and the pile head of the pile driven into the ground can be reinforced. [Brief description of the drawings]

[0022] [Figure 1] 1A and 1B show a steel pipe pile used in an embodiment of a pile driving method according to the present invention, in which (a) is a front view and (b) is a cross-sectional view taken along line AA of (a). [Diagram 2] 1A and 1B show a pile driving machine used in the pile driving method according to the present invention, in which (a) is a left side view and (b) is a front view. [Diagram 3] 2A to 2C show a connection jig of a driving machine for driving the steel pipe pile shown in FIG. 1, where (a) is a plan view, (b) is a side view, and (c) is a cross-sectional view along line BB of (a). [Figure 4] 1A is a perspective view of the locking portion of the connection jig, FIG. 1B is a cross-sectional view of the connection jig when connected to a steel pipe pile, and FIG. 1C is a cross-sectional view of line CC of FIG. [Diagram 5] 2 shows a reinforcement body pressed in together with the steel pipe pile shown in FIG. 1, where (a) is a front view, (b) is a side view, and (c) is a DD line cross-sectional view of (a). [Figure 6] 1(a) to 1(d) are schematic diagrams showing each step of the pile driving method according to the present embodiment. [Figure 7] 7A to 7C are schematic diagrams showing steps subsequent to the steps shown in FIG. 6. [Figure 8] (a) is a plan view of a reinforcing body according to a modified example, (b) is a cross-sectional view along line EE of (a), (c) is a cross-sectional view of a reinforcing body according to another modified example, and (d) is a modified example of a ring used in the reinforcing body shown in (c). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] 1. Piles (steel pipe piles) used in the driving method 1 Hereinafter, an embodiment of the pile driving method according to the present invention will be described in detail with reference to the drawings. Figure 1 shows a steel pipe pile used in the embodiment of the pile driving method according to the present invention, where (a) is a front view and (b) is a cross-sectional view taken along line AA in (a).

[0024] First, a steel pipe pile 1 used in the pile driving method according to the present embodiment will be described in detail with reference to FIG. 1. The steel pipe pile 1 is formed of a steel pipe material (steel pipe) 2, and is driven vertically into the ground 5 (see FIG. 6) to support the foundation of a building or the like. Both ends of the pipe material 2 are closed by welding or the like, but may be left open. A spiral tip wing 3 made of a steel plate is fixed to one end (lower end) of the steel pipe pile 1 by welding or the like. However, the tip wing 3 is not limited to a spiral shape, and may be a wing in which a pair of inclined semicircular plates are fixed to the tip of the steel pipe pile 1, and the shape of the tip wing 3 is not particularly limited as long as it is a shape that promotes the penetration of the steel pipe pile 1.

[0025] The spiral tip wing 3 is fixed along the outer circumferential surface of the pipe material 2. Specifically, it is a positive spiral wing that drives the steel pipe pile 1 into the ground when the steel pipe pile 1 is rotated in one direction by a driving machine. For example, when the steel pipe pile 1 is set vertically and rotated in one direction (clockwise) in a plan view, the steel pipe pile 1 is inclined spirally so that the tip wing 3 penetrates the ground. The tip wing 3 is formed for approximately one revolution, but may be formed for multiple revolutions.

[0026] A protrusion 4 is formed on the pile head 1a at the top of the steel pipe pile 1, protruding from the inner peripheral surface toward the axis of the pile 1. The protrusion 4 is formed of a rectangular steel plate and is fixed to the inner peripheral surface of the pile head 1a along the axial direction by welding or the like. The protrusion 4 engages with a locking recess 15d of a locking portion 15 of a connecting jig 10, which will be described later. The engaging protrusions 4 may be formed in multiple locations. For example, when there are two protrusions 4, they may be formed at positions symmetrical with respect to the central axis when viewed from above. As long as the protrusions 4 of the steel pipe pile 1 and the connecting jig 10 engage with each other in the rotational direction, their positions are not limited.

[0027] 2. About the connection jig 10 and the casting machine 30 The connection jig 10 is a jig that connects the driving machine 30 and the pile 1. As shown in Figs. 2(a) and (b), the driving machine 30 is equipped with a driver's room and an engine room on a chassis 30A. An arm 31 is held vertically on the chassis 30A, and the angle of the arm 31 can be changed to an inclined or horizontal state by a hydraulic cylinder. A lifting head 32 is attached to the arm 31 so that it can move up and down. The connection jig 10 for connecting the steel pipe pile 1 is connected and fixed to the lower part of the lifting head 32, and a drive unit (not shown) such as a hydraulic motor for rotating the connection jig 10 is built in.

[0028] As shown in Figures 3(a) to (c), the connection jig 10 has a tubular connecting portion 11 connected to the driving machine 30, and a plate portion 12 fixed to the lower end of the connecting portion 11 and abutting the upper end surface 26 of the reinforcement body 20 described later.

[0029] As shown in FIG. 4(a), the locking part 15 has a base end fixed to the plate part 12, has a cylindrical shape smaller than the inner diameter of the steel pipe pile 1, and is tapered at its tip. The axis of the locking part 15 coincides with the rotation axis of the steel pipe pile 1 when the steel pipe pile 1 is driven. The locking part 15 has a cylindrical main body part 15a and a truncated cone-shaped tapered part 15b extending downward from the main body part 15a, and the tapered part 15b can guide the steel pipe pile 1 (pile head part 1a) to the locking part 15.

[0030] As shown in Fig. 4(a), the locking portion 15 may have a through hole 15g formed along the axis of the locking portion 15. In this embodiment, a guide groove 15c is formed along the axial direction on the peripheral surface of the locking portion 15. The guide groove 15c can guide the protrusion 4 formed on the inner peripheral surface of the steel pipe pile 1 along the axial direction.

[0031] A locking recess 15d is formed in the circumferential direction on the peripheral surface of the locking portion 15 at the base end side so as to be continuous with the guide groove 15c. The locking recess 15d provides the main body 15a of the locking portion 15 with a first abutment surface 15f formed along the axial direction and a second abutment surface 15e formed along the circumferential direction.

[0032] As a result, when the connection jig 10 is rotated in the forward direction with respect to the steel pipe pile 1 (pile head portion 1a) by the driving machine 30 with the convex portion 4 of the steel pipe pile 1 accommodated in the guide groove 15c, the convex portion 4 is accommodated in the locking recess 15d and abuts against the first abutment surface 15f, as shown in FIG. 4(b). Furthermore, when the steel pipe pile 1 is pulled up by the driving machine 30, the convex portion 4 abuts against the second abutment surface 15e, as shown in FIG. 4(c), and the steel pipe pile 1 can be supported via the connection jig 10. Note that when the steel pipe pile 1 is driven, the end face of the pile head portion 1a abuts against the plate portion 12.

[0033] Furthermore, as shown in Figs. 3(a) to (c), the connecting jig 10 has an engaging protrusion 16 that protrudes from the plate portion 12 to the reinforcing body 20 and engages with each engaging recess 23 formed in the reinforcing body 20. As shown in Fig. 6(c) described later, when the reinforcing body 20 is inserted into the pile head portion 1a of the steel pipe pile 1, a gap S is formed between the outer circumferential surface of the pile head portion 1a of the steel pipe pile 1 and the inner circumferential surface of the through hole 22b of the reinforcing body 20. The plate portion 12 of the connecting jig 10 is formed with a guide tube 13 that is inserted into this gap S. As shown in Fig. 7(a) described later, the guide tube 13 is disposed between the outer circumferential surface of the pile head portion 1a of the steel pipe pile 1 and the inner circumferential surface of the through hole 22b of the reinforcing body 20, with the engaging protrusion 16 of the connecting jig 10 engaged with the engaging recess 23 of the reinforcing body 20.

[0034] An engagement portion 15 that engages with the pile head portion 1a of the steel pipe pile 1 is formed on the underside of the plate portion 12. Specifically, a plurality of (for example, three) engagement protrusions 16 are formed around the axis of the connecting jig 10 on the underside of the plate portion 12. Specifically, each rib 14 is a right-angled triangular plate material, and is formed so as to bridge the peripheral side surface of the connecting portion 11 and the upper surface of the plate portion 12. On the upper surface of the plate portion 12, ribs 14 are formed at positions corresponding to each engagement protrusion 16.

[0035] By providing the rib 14 at such a position, deformation of the engaging protrusion 16 and the plate portion 12 due to the load in the pressing direction and the torque in the circumferential direction acting from the reinforcing body 20 on the engaging protrusion 16 when the reinforcing body 20 is pressed in can be prevented.

[0036] 3. Reinforcement body 20 The reinforcing body 20 is a member that reinforces the bearing capacity of the steel pipe pile 1 driven into the ground 5. The material of the reinforcing body 20 is not particularly limited as long as it can reinforce the bearing capacity of the steel pipe pile 1, such as resin, metal, and wood. The reinforcing body 20 has a cylindrical main body 21A and a tapered truncated cone portion 21B that continues from the circumferential surface of the main body 21A. The reinforcing body 20 has a through hole 22 that passes through the pile head 1a along the axis of the reinforcing body 20. The through hole 22 has a small diameter through hole 22a through which only the pile head 1a is inserted, and a large diameter through hole 22b through which the guide tube 13 that covers the pile head 1a is inserted.

[0037] 5(a) and (b), the upper end surface 26 of the reinforcing body 20 is the surface that abuts against the plate portion 12 of the connecting jig 10. The engaging protrusions 16 of the connecting jig 10 are inserted into the upper end surface 26, and a plurality of (e.g., three) engaging recesses 23 that engage with the engaging protrusions 16 are formed around the axis of the reinforcing body 20. Note that, if the reinforcing body 20 can be rotated around the axis, there may be one or more pairs of engaging recesses 23 and engaging protrusions 16 that engage therewith.

[0038] 5(b) and (c), a helical blade 24 is formed along the circumferential direction on the conical surface of the truncated cone portion 21B of the reinforcing body 20. By providing the helical blade 24 on the truncated cone portion 21B, the truncated cone portion 21B of the reinforcing body 20 has a screw shape like the tip of a screw.

[0039] In this embodiment, the helical blade 24 has the same helical direction as the helical tip blade 3 of the steel pipe pile 1, and is formed in a direction that scoops out soil and sand from the ground 5 when rotating in the forward rotation direction CW. However, the helical blade 24 may have a helical direction opposite to that of the helical tip blade 3 of the steel pipe pile 1, and the helical blade 24 may push in soil and sand in the surface layer of the ground 5 when rotating in the forward rotation direction CW. This makes it possible to compact the surface layer of the ground 5 on which the reinforcing body 20 is placed.

[0040] 4. Steel pipe pile 1 installation method A method for driving a steel pipe pile 1 according to an embodiment will be described below with reference to Figures 6 and 7. In the method for driving a steel pipe pile 1, as shown in Figure 2(a), the connecting portion 11 of the connection jig 10 is attached to the lifting head 32 of a driving machine 30, and the connection jig 10 is connected to the driving machine 30. Next, as shown in Figure 6(a), the steel pipe pile 1 is erected vertically on the ground 5, the pile head 1a of the steel pipe pile 1 is inserted into the guide tube 13, and the connection jig 10 is rotated slightly in the forward direction CW. In this way, the steel pipe pile 1 is attached to the connection jig 10 (attaching process).

[0041] In this mounting step, as explained in Figures 4(a) to (c), the protrusion 4 formed on the inner peripheral surface of the upper part of the steel pipe pile 1 is moved relatively along the guide groove 15c formed in the locking part 15 of the connecting jig 10, and then the steel pipe pile 1 is rotated in the normal direction CW (see, for example, Figure 6(a)), whereby the protrusion 4 is accommodated in the locking recess 15d. This allows the steel pipe pile 1 to be suspended from the connecting jig 10.

[0042] In addition, when the piles are wooden piles or concrete piles, since no protrusions 4 are provided on the wooden piles or concrete piles, the connecting jig 10 is lowered with the wooden piles or concrete piles standing, and the connecting jig 10 is attached to the connecting jig 10 from above. In this case, since no protrusions 4 are provided on the wooden piles or concrete piles, the connecting jig 10 does not need to be provided with the locking portion 15. Note that by applying tension again to the wire that suspends the pile, fine adjustments to the casting position are possible.

[0043] After this attachment step, as shown in FIG. 6(b), the process proceeds to the first driving step, in which the steel pipe pile 1 is driven into the ground 5 by the driving machine 30 while rotating the steel pipe pile 1 together with the connection jig 10 in the forward direction CW.

[0044] This first driving step is performed while rotating the connection jig 10 in the forward direction CW. The soil of the ground 5 excavated by the tip blade 3 is in a soft state. The lifting head 32 of the driving machine 30 applies a downward driving force to the steel pipe pile 1 via the connection jig 10, causing it to penetrate into the ground 5.

[0045] In addition, when the piles are wooden piles or concrete piles, the wooden piles and concrete piles are not provided with the protrusions 4. Therefore, the wooden piles and concrete piles are not engaged with the connecting jig 10, so the connecting jig 10 may be performed without rotating.

[0046] In the first driving step, with the pile head 1a of the steel pipe pile 1 remaining at a predetermined height above the ground surface, the connecting jig 10 is rotated in the reverse direction CCW as shown in Fig. 6(c), and then the connecting jig 10 is pulled up vertically to remove (separate) the connecting jig 10 from the pile head 1a of the steel pipe pile 1. In this state, the pile head 1a is inserted into a through hole formed in the reinforcing body 20.

[0047] In this state, the connection jig 10 is attached to the pile head 1a again by the same operation as that described in Fig. 6(a) and (b), and the driving machine 30 drives the steel pipe pile 1 into the ground 5 to the vicinity of the reinforcing body 20 while rotating in the forward direction CW as shown in Fig. 6(d). This is the first driving step, in which the driving machine 30 drives the steel pipe pile 1 from the ground surface to the ground 5, leaving the pile head 1a of the steel pipe pile 1, with the pile head 1a of the steel pipe pile 1 connected to the driving machine 30. Note that in the first driving step, the connection jig 10 is separated from the pile head 1a of the steel pipe pile 1 as shown in Fig. 6(c), but after the steel pipe pile 1 is driven into the ground 5 to the position shown in Fig. 7(a), for example, the reinforcing body 20 may be inserted into the pile head 1a as shown in Fig. 6(c).

[0048] Next, as shown in Fig. 7(a), in the second driving step, the pile head 1a is inserted into the through-hole 22 formed in the reinforcing body 20, and while driving the pile head 1a, the reinforcing body 20 is pressed into the ground 5. In this embodiment, the reinforcing body 20 is pressed into the surface of the ground 5 together with the pile head 1a of the steel pipe pile 1 until the end face of the pile head 1a of the steel pipe pile 1 and the upper end face 26 of the reinforcing body 20 are flush with each other, as shown in Fig. 7(b).

[0049] Specifically, in the second driving step, with the truncated cone portion 21B facing downward, the engaging convex portion 16 of the connecting jig 10 is engaged with the engaging concave portion 23 of the reinforcing body 20, and then the reinforcing body 20 is pressed into the ground 5 while rotating together with the steel pipe pile 1 in the normal rotation direction CW around the axis of the steel pipe pile 1. As a result, after the engaging convex portion 16 of the connecting jig 10 is engaged with the engaging concave portion 23 of the reinforcing body 20, the reinforcing body 20 can be rotated in the same normal rotation direction (CW) while rotating around the axis of the steel pipe pile 1, thereby allowing the reinforcing body 20 to be stably pressed into the ground 5.

[0050] More specifically, when engaging the engagement convex portion 16 of the connection jig 10 with the engagement concave portion 23 of the reinforcing body 20, the guide tube 13 of the connection jig 10 is inserted into the gap S, and then the reinforcing body 20 is pressed into the ground 5 while rotating in the forward direction (CW) around the axis of the steel pipe pile 1.

[0051] As a result, with the guide tube 13 inserted into the gap S formed between the outer surface of the pile head 1a of the steel pipe pile 1 and the inner surface of the through hole 22 (22b) of the reinforcing body 20, the reinforcing body 20 is pressed into the ground while rotating around the axis of the steel pipe pile 1.

[0052] As a result, it is possible to prevent the axis of the reinforcing body 20 from tilting or becoming misaligned during pressing, and further to prevent deformation of the pile head 1a of the steel pipe pile 1. In this way, the steel pipe pile 1 can be driven with high precision while being guided by the guide tube 13 of the connection jig 10 along the driving direction (vertical direction) of the steel pipe pile 1.

[0053] Next, as shown in Fig. 7(b), after the second casting step, the connection jig 10 is rotated in the reverse direction CCW as described in Fig. 6(c), and then the connection jig 10 is pulled up vertically to remove (separate) the connection jig 10 from the pile head 1a of the steel pipe pile 1. As shown in Fig. 7(c), a ring 28 is inserted so as to fill the gap S formed at the position where the guide tube 13 was inserted (see Fig. 7(d)). Furthermore, a cap 29 is placed over the pile head 1a.

[0054] According to this embodiment, the reinforcing body 20 is disposed around the pile head 1a, so that soil equivalent to the volume of the reinforcing body 20 can be pressurized by the reinforcing body 20 and compacted around the pile head 1a of the steel pipe pile 1. As a result, the density of the ground directly below the foundation increases, improving the performance of the vertical bearing capacity and horizontal bearing capacity, and reducing the vertical and horizontal displacement amounts.

[0055] Because the steel pipe pile 1 and the reinforcing body 20 can be driven into the ground at the same time, there is no need to form a recess to embed the reinforcing body 20, and the surface ground will not collapse toward the pile. Furthermore, there is no need to compact the ground 5 around the pile head 1a, which reduces the number of people and labor required for on-site construction and shortens the construction period.

[0056] In this embodiment, the reinforcing body 20 is pressed in with the truncated cone portion 21B facing downward, so that not only is it easier to press the reinforcing body 20 into the ground 5, but the truncated cone portion 21B can compact the ground around the pile head portion 1a when the reinforcing body 20 is pressed in. When the reinforcing body 20 is rotated in a direction in which the helical blade 24 of the reinforcing body 20 pushes the soil in the ground 5 downward, the tip blade 3 formed at the tip of the steel pipe pile 1 can compact the loosened soil in the surface layer of the ground. On the other hand, when the reinforcing body 20 is rotated in a direction in which the helical blade 24 scoops out the soil in the ground, the reinforcing body 20 can be pressed in while scooping out the soil in the case where the surface layer of the ground is a hard layer.

[0057] In the case where the pile is a steel pipe pile, a wooden pile, or a concrete pile that does not have a tip wing 3, a reinforcing body 20A that does not have a spiral wing 24 may be pressed into the ground 5 together with such a pile, as shown in Figures 8(a) and (b). Furthermore, if a stepped tapered portion 22c is provided in the through hole 22 of the reinforcing body 20A as shown in Figure 8(c), a ring 28A having a tapered portion 28a formed at its tip can be easily inserted into the gap S shown in Figure 7(c) as shown in Figure 8(d).

[0058] In this way, by inserting the rings 28, 28A shown in Figures 7(c) and 8(d), the pile and the reinforcing body 20 can be firmly connected, and the vertical and horizontal bearing forces of the pile can be improved. Note that the rings 28, 28A may be formed integrally with the cap 29.

[0059] Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above-described embodiments, and various design modifications can be made without departing from the spirit of the present invention described in the claims. The present invention allows the configuration of one embodiment to be added to the configuration of another embodiment, the configuration of one embodiment to be replaced with another embodiment, or part of the configuration of one embodiment to be deleted. [Explanation of symbols]

[0060] 1: steel pipe pile (pile), 1a: pile head, 3: tip wing, 4: convex portion, 5: ground, 10: connection jig, 12: plate portion, 13: guide tube, 16: engaging convex portion, 20: reinforcing body, 21A: main body portion, truncated cone portion 21B, 22: through hole, 23: engaging concave portion, 26: upper end surface, 28: ring, 30: driving machine

Claims

1. A pile driving method in which a cylindrical reinforcing body that reinforces the bearing capacity of a pile driven into the ground is driven into the ground together with the pile using a driving machine, A first driving step of driving the pile into the ground from the ground surface by the driving machine with the pile head of the pile connected to the driving machine, leaving the pile head of the pile; A pile driving method comprising: a second driving step of driving the pile head into the ground while driving the reinforcement body with the pile head inserted into a through hole formed in the reinforcement body.

2. The reinforcing body has a cylindrical main body portion and a tapered truncated cone portion continuing from a circumferential surface of the main body portion, 2. The pile driving method according to claim 1, wherein in the second driving step, the reinforcing body is pressed in with the truncated cone portion facing downward.

3. 3. The pile driving method according to claim 2, characterized in that in the second driving step, the reinforcing body is pressed into the ground while being rotated around the axis of the pile.

4. 4. The pile driving method according to claim 3, wherein a helical blade is formed along a circumferential direction on a conical surface of the truncated cone portion.

5. The pile head of the pile is connected to the driving machine via a connecting jig, At least one engagement recess that engages with the connecting jig is formed on the upper end surface of the reinforcing body along an axis of the reinforcing body, The connection jig has a connecting portion connected to the driving machine, a plate portion fixed to the lower end of the connecting portion and abutting the upper end surface of the reinforcement body, and an engaging protrusion protruding from the plate portion to the reinforcement body and engaging with each engaging recess formed on the reinforcement body, A pile driving method as described in claim 3, characterized in that in the second driving step, the engaging convex portion of the connection jig is engaged with the engaging concave portion of the reinforcement body, and then the reinforcement body is pressed into the ground while rotating around the axis of the pile.

6. A guide tube is formed in the plate portion and is inserted into a gap formed between an outer peripheral surface of the pile head and an inner peripheral surface of the through hole of the reinforcement body when the pile head is inserted into the reinforcement body, A pile driving method as described in claim 5, characterized in that in the second driving step, the engaging convex portion of the connection jig is engaged with the engaging concave portion of the reinforcement body and the guide tube of the connection jig is inserted into the gap, and then the reinforcement body is pressed into the ground while rotating around the axis of the pile.

7. The pile driving method according to claim 6, characterized in that after the second driving step, the connecting jig is removed from the reinforcing body, and a ring is inserted so as to fill the gap into which the guide tube is inserted.

8. The reinforcing body used in the pile driving method according to claim 1, The reinforcing body is characterized in that it has a cylindrical main body portion and a tapered truncated cone portion continuing from the circumferential surface of the main body portion.

9. The connection jig used in the pile driving method according to claim 5, The connection jig is characterized by having a connecting portion connected to the driving machine, a plate portion fixed to the lower end of the connecting portion and abutting the upper end surface of the reinforcement body, and an engaging protrusion portion protruding from the plate portion to the reinforcement body and engaging with an engaging recess portion formed on the reinforcement body.

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