Drilling unit

Abstract

To provide a drilling unit capable of stably drilling the ground around a head of a pile driven into the ground.SOLUTION: A drilling unit 100 includes a drilling jig 40 that rotates about an axis of a foundation pile 1 as a rotation axis CL and drills the ground G around a pile head 1a, and a guide jig 20 that is attached to the pile head 1a and guides the drilling jig 40 along the axis of the foundation pile 1. The guide jig 20 includes an attachment part 22 that is attached to the pile head 1a from above, and a guide part 21 that extends upward along the axis of the foundation pile 1 and guides the drilling jig 40 with the attachment part 22 attached to the pile head 1a. The drilling jig 40 includes a cylindrical casing 41 having an opening 41a into which the guide part 21 is inserted from above the guide part 21, and a drilling blade 43 that has a blade tip 43t inclined with respect to the rotation axis CL and is fixed to the casing 41 so as to scrape out soil and sand from the ground G by rotation in one direction around the rotation axis CL.SELECTED DRAWING: Figure 7A

Description

[Technical field]

[0001] The present invention relates to a drilling unit that excavates the ground around the pile head of a foundation pile buried in the ground. [Background technology]

[0002] As an example of this type of technology, Patent Document 1 discloses an excavation tool for excavating the ground around the head of a foundation pile buried in the ground. This excavation tool has a cylindrical casing that rotates around the axis of the foundation pile as the rotation axis, and a propulsion blade (digging blade) that is attached to the tip of the casing and excavates the ground. The propulsion blade has a spiral blade shape that goes around the rotation axis of the casing. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2014-66010 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, for example, when trying to excavate the ground around the head of a foundation pile that has been driven into the ground so that the head of the pile is positioned deeper than the surface level, it is difficult to smoothly guide the excavation jig connected to the excavator to the head of the pile.

[0005] The present invention has been made in consideration of these points, and its object is to provide a drilling unit that can smoothly excavate the ground around the head of a pile that is placed deeper than the ground surface using an excavation jig. [Means for solving the problem]

[0006] In consideration of the above problems, the present invention provides an excavation unit that excavates the ground around a head of a foundation pile that is driven into the ground so that the head of the pile is positioned deeper than the surface of the ground. The excavation unit comprises: a drilling jig that rotates about the axis of the foundation pile as a rotation axis and excavates the ground around the head of the pile; and a guide jig that is attached to the head of the pile and guides the excavation jig along the axis of the foundation pile. The guide jig comprises an attachment part that is attached to the head of the pile from above the head of the pile, and a guide part that extends upward along the axis of the foundation pile when the attachment part is attached to the head of the pile, and guides the excavation jig. The excavation jig comprises a cylindrical casing having an opening for inserting the guide part from above the guide part, and a drilling blade fixed to the casing, the blade tip of which is inclined with respect to the rotation axis so as to scrape out soil and sand from the ground by rotation in one direction around the rotation axis.

[0007] According to the present invention, the mounting portion of the guide jig can be attached to the pile head portion of the foundation pile that has been driven and positioned deeper than the ground surface. When the mounting portion of the guide jig is attached to the pile head portion from above the pile head portion, the guide portion of the guide jig extends above the pile head portion along the axis of the foundation pile. In this state, the opening of the casing of the excavation jig connected to the excavator is inserted into the guide portion from above the guide jig. In this way, the excavation jig can be used to smoothly excavate the ground around the pile head portion that has been positioned deeper than the ground surface.

[0008] Specifically, the axis of the foundation pile is used as the axis of rotation, and the excavation jig is rotated in one direction (forward direction) around the axis of rotation while being pushed into the ground. This makes it possible to excavate the ground around the pile head while scraping out soil from the ground with the excavation blade fixed to the casing and inclined relative to the axis of rotation. After excavation, the excavation jig is rotated in the other direction (reverse direction) around the axis of rotation while being pushed into the ground, thereby compacting the bottom surface of the excavation hole formed by excavation.

[0009] In a more preferred embodiment, the pile head is formed with a locking protrusion that engages with the guide jig, and the mounting portion has a guide portion that guides the locking protrusion from the lower end of the guide jig along the axial direction of the guide jig, and the edge of the guide portion is formed with a locking edge that engages with the locking protrusion so as to limit the upward movement of the guide jig by the guide portion protruding circumferentially of the guide jig.

[0010] According to this aspect, the locking protrusion formed on the pile head is guided along the guide portion formed on the mounting portion. Since the guide portion is formed to protrude in the circumferential direction of the guide jig, the guide jig rotates in the circumferential direction. As a result, when the excavation jig connected to the excavator is pulled upward after the ground is excavated, the locking edge of the guide portion locks onto the locking protrusion so as to restrict the upward movement of the guide jig. As a result, the excavation jig can be separated from the guide jig while the guide jig is attached to the pile head. In this way, even if the excavated soil or the like is clogged between the guide jig and the excavation jig, making it difficult to separate the guide jig and the excavation jig, they can be easily separated.

[0011] In a more preferred embodiment, a guide member is attached to the mounting portion to guide the guide jig from the opening of the casing into the inside of the casing, and the guide member is a linear member bent upward from a position facing the upper edge of the guide jig toward the axis of the guide jig.

[0012] According to this aspect, as described above, when the mounting portion of the guide jig is mounted on the pile head from above the pile head, the guide portion of the guide jig extends upward along the axis of the foundation pile. In this state, the linear member serving as the guiding member is bent upward from the position facing the upper edge of the guide jig (guiding portion) toward the axis of the guide jig, so that the guide portion of the guide jig can be smoothly inserted from above into the opening of the casing of the excavation jig. Meanwhile, by using the linear member serving as the guiding member as a handle, the guide jig can be easily mounted on the pile head, and after excavation, the excavation jig can be separated from the guide jig and the guide jig can be easily removed from the pile head.

[0013] In a preferred embodiment of the drilling jig, the drilling blade is fixed to the outer peripheral surface of the casing and is formed in a spiral shape so as to rotate multiple times around the rotation axis of the drilling jig, and the cutting edge of the drilling blade, which is formed in the circumferential direction at the tip side of the casing, is formed so that the distance between the rotation axis and the cutting edge increases as it progresses from the tip of the casing toward the base end.

[0014] According to this embodiment, the excavation blade is helical (helical blade-shaped) and fixed so as to rotate multiple times. As a result, the excavation tool can be rotated in one direction (positive direction) around the rotation axis while being pushed into the ground, thereby efficiently excavating the ground around the head of the foundation pile. Because the excavation blade is formed in a helical shape, the soil generated by excavation can be discharged to the top.

[0015] In particular, at the tip of the casing, the cutting edge formed in the circumferential direction of the excavation blade is formed so that the distance between the rotation axis and the cutting edge increases as it moves from the tip of the casing to the base end, so that the ground around the pile head can be excavated while the excavation tool is pushed into the ground more efficiently. Also, after excavation, the bottom surface of the excavation hole formed by excavation can be compacted by pushing the excavation tool into the ground while rotating it in the other direction (reverse direction) around the rotation axis.

[0016] Another preferred embodiment of the excavation jig is one in which the excavation jig is attached to the outer peripheral surface of the tip side of the casing and has an umbrella-shaped portion having the shape of the side of a truncated cone expanding from the tip side to the base side of the casing, the excavation blade rises at an incline circumferentially relative to the outer peripheral surface of the umbrella-shaped portion, the cutting edge is formed along the direction of the generatrix of the truncated cone, and a through hole is formed in the umbrella-shaped portion at the base end of the excavation blade to allow the soil to pass through to the inner peripheral surface of the umbrella-shaped portion.

[0017] According to this embodiment, the excavation blade rises at an incline in the circumferential direction relative to the outer circumferential surface of the umbrella-shaped portion, and the cutting edge is formed along the generatrix direction of the truncated cone. This allows the excavation tool to be rotated in one direction (positive direction) around the rotation axis while being pushed into the ground, thereby efficiently excavating the ground around the head of the foundation pile. Since the umbrella-shaped portion has a through hole at the base end of the excavation blade, the soil generated by excavation can be passed through the through hole to the inner circumferential surface side of the umbrella-shaped portion and discharged above the excavation blade.

[0018] In particular, since the cutting edge is formed along the generatrix direction of the truncated cone, the ground around the pile head can be excavated while the excavation jig is pushed into the ground more efficiently. After excavation, the bottom surface of the excavation hole formed by excavation can be compacted by pushing the excavation jig into the ground while rotating the excavation jig in the other direction (reverse direction) around the rotation axis.

[0019] In another preferred embodiment of the excavation jig, the excavation blade is a plate-shaped member fixed to the outer peripheral surface of the tip side of the casing at an angle with respect to the rotation axis of the excavation jig, and is fixed to the outer peripheral surface of the tip side of the casing at intervals in the circumferential direction of the casing in multiple pieces. The excavation jig has a cylindrical frame body with the rotation axis as its axis fixed to the casing via the excavation blade, and the excavation blade is arranged between the inner peripheral surface of the frame body and the outer peripheral surface of the casing so that the cutting edge portion on the tip side of the casing is exposed. A gap is formed between adjacent excavation blades to allow the soil to pass from below the frame body into the internal space of the frame body.

[0020] According to this aspect, the excavation blade is a plate-shaped member fixed to the outer peripheral surface of the tip side of the casing at an angle with respect to the rotation axis of the casing, and a plurality of the excavation blades are fixed to the outer peripheral surface of the tip side of the casing at intervals in the circumferential direction of the casing. As a result, the excavation tool can be rotated in one direction (positive direction) around the rotation axis while being pushed into the ground, thereby efficiently excavating the ground around the head of the foundation pile. Since a gap is formed between adjacent excavation blades, the soil generated by excavation can pass from below the frame body to the internal space of the frame body through the gap between the excavation blades and be discharged above the excavation blades.

[0021] In particular, the excavation blade is positioned between the inner surface of the frame body and the outer surface of the casing so that the cutting edge at the tip of the casing is exposed, so that the excavation jig can be pushed into the ground more efficiently while excavating the ground around the pile head.

[0022] Since the outer peripheral surface of the cylindrical frame moves along the side wall surface of the excavated hole in the excavated ground, it is possible to prevent the side wall surface of the excavated hole around the pile head formed after excavation from collapsing. Since the soil generated by excavation exists in the internal space of the cylindrical frame and above it, when the excavation tool is pulled up from the ground, the soil can be efficiently discharged from the excavated hole while preventing the side wall surface of the excavated hole around the pile head formed after excavation from collapsing. In addition, after excavation, the excavation tool can be pushed into the ground while rotating in the other direction (reverse direction) around the rotation axis, thereby compacting the bottom surface of the excavated hole formed by excavation. Effect of the Invention

[0023] According to the present invention, the ground around the head of a pile that is placed deeper than the ground surface can be smoothly excavated using an excavation jig. [Brief description of the drawings]

[0024] [Figure 1] 1A and 1B show a steel pipe pile used in an embodiment of a pile driving method, in which (a) is a front view and (b) is a cross-sectional view taken along line AA in (a). [Diagram 2] 1A and 1B show a pile driving machine used in a pile driving method according to the present invention, in which (a) is a left side view and (b) is a front view. [Diagram 3] 2 shows a first connection jig of a driving machine for driving the steel pipe pile shown in FIG. 1, where (a) is a side view of the main part of the first connection jig, (b) is an oblique view of the locking part of the first connection jig of (a), and (c) is a cross-sectional view for explaining the driving of a steel pipe pile using the first connection jig of (a). [Figure 4] FIG. 2 is a schematic diagram of a guide jig to be connected to the pile head of a steel pipe pile. [Figure 5A] FIG. 2 is a side view of the drilling jig according to the first embodiment. [Figure 5B] 5B is a schematic perspective view of the excavation jig shown in FIG. 5A, and FIG. 5C is a schematic perspective view of the excavation jig as viewed from below in FIG. 5A. FIG. [Figure 6]13 is a schematic perspective view for explaining a method of connecting the drilling jig and the second connecting jig. FIG. [Figure 7A] 3(a) to 3(c) are diagrams illustrating a method for reinforcing a foundation pile using the excavation jig shown in FIG. [Figure 7B] 7A to 7C are views for explaining a method of reinforcing a foundation pile, following FIG. 7A(c). [Figure 8A] FIG. 13(a) is a schematic perspective view of a drilling jig according to a second embodiment, and (b) is a schematic perspective view of the drilling jig as viewed from below in (a). [Figure 8B] FIG. 13(a) is a cross-sectional view taken along the axial direction of a drilling jig according to a second embodiment, and FIG. 13(b) is a cross-sectional view taken along line BB in FIG. [Figure 9A] FIG. 11 is a schematic side view of the drilling jig according to the third embodiment. [Figure 9B] 9A is a top view of the excavation jig shown in FIG. 9A, and FIG. 9B is a cross-sectional view taken along line CC in FIG. 9A. [Figure 9C] 9B is a schematic perspective view of the excavation jig shown in FIG. 9A, and FIG. 9C is a schematic perspective view of the excavation jig as viewed from below in FIG. 9A. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025] Hereinafter, drilling units according to first to third embodiments of the present invention and a method of reinforcing a foundation pile using the same will be described with reference to Figs. 1 to 9C.

[0026] [First embodiment] As the foundation pile 1 used in this embodiment, a steel pipe pile is illustrated as an example, but is not limited thereto, and may be a wooden pile, a concrete pile, or the like, as long as it can be connected to the first and second connecting jigs 10A and 10B described below. Below, as an example, the foundation pile 1 will be described in detail with reference to FIG. 1. The foundation pile 1 is formed of a steel pipe material (steel pipe) 2, is driven vertically into the ground G (see FIG. 7A(a)), and supports the foundation of a building, for example. The lower end of the pipe material 2 is 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 foundation 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 foundation pile 1, and the shape of the tip wing 3 is not particularly limited as long as it has a shape that promotes the penetration of the foundation pile 1.

[0027] 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 foundation pile 1 into the ground when the foundation pile 1 is rotated in one direction by a driving machine. For example, when the foundation pile 1 is set vertically and rotated in one direction (clockwise) in a plan view, the foundation 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.

[0028] The pile head 1a at the top of the foundation pile 1 is formed with a convex portion (locking convex portion) 4 that protrudes from the inner peripheral surface toward the axis of the foundation pile 1. The convex portion 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 convex portion 4 engages with a first abutment surface 16d of the locking portion 15 of the first connecting jig 10A described later. The convex portion 4 may be formed in multiple locations. For example, when there are two convex portions 4, they may be formed at positions symmetrical with respect to the central axis when viewed from above. As long as the convex portion 4 of the foundation pile 1 and the first connecting jig 10A engage in the rotational direction, the position is not limited.

[0029] 1. About the driving machine 30 and the first connecting jig 10A The first connecting jig 10 is a jig that connects the driving machine 30 and the foundation pile 1. As shown in Figs. 2(a) and (b), the driving machine 30 is provided with a driver's room and an engine room on the chassis 30A. The chassis 30A holds an arm 31 in a vertical state, and the arm 31 is configured to be able to change its angle to an inclined state or a horizontal state by a hydraulic cylinder. The arm 31 is equipped with a lifting head 32 that can move up and down. The lifting head 32 has a first connecting jig 10A for connecting the foundation pile 1 connected and fixed to the lower part of the lifting head 32, and a drive unit (not shown) such as a hydraulic motor for turning the first connecting jig 10A is built in. Similarly, when excavation is performed using excavation jigs 40A to 40C described later, the lifting head 32 has a second connecting jig 10B described later connected and fixed to the lower part of the lifting head 32.

[0030] As shown in Figure 3, the first connection jig 10 has a tubular connecting portion 11A connected to the driving machine 30, and a plate portion 13A fixed to the lower end of the connecting portion 11A and abutting the upper end surface of the pile head portion 1a described later.

[0031] Furthermore, as shown in FIG. 3, the first connecting jig 10A is formed with a cylindrical locking portion 15 having a guide groove 16 that is locked by the convex portion 4 of the pile head portion 1a, and a cylindrical guide tube 12A that covers and guides the pile head portion 1a. The locking portion 15 is housed in the guide tube 12A so that the tapered portion 15a of the locking portion 15 is exposed. The locking portion 15 has a base end fixed to the plate portion 13A, has a cylindrical shape smaller than the inner diameter of the foundation pile 1, and has a tapered tip. The base end of the guide tube 12A is also fixed to the plate portion 13A, and the guide tube 12A also has a cylindrical shape larger than the inner diameter of the foundation pile 1. The pile head portion 1a is inserted into the gap formed between the guide tube 12A and the locking portion 15. The axis of the locking portion 15 coincides with the rotation axis of the foundation pile 1 when the foundation pile 1 is driven. The engaging portion 15 has a tapered portion 15a in the shape of a truncated cone extending downward, and the tapered portion 15a makes it possible to guide the foundation pile 1 (pile head portion 1a) into the engaging portion 15.

[0032] In this embodiment, as shown in FIG. 3(b), a first groove 16a is formed in the peripheral surface 15b of the locking portion 15 along the axial direction. The first groove 16a can guide the protrusion 4 formed on the inner peripheral surface of the foundation pile 1 along the axial direction. A second groove 16b is formed in the peripheral surface 15b of the locking portion 15 in the circumferential direction at the base end side so as to be continuous with the first groove 16a. The second groove 16b provides the main body of the locking portion 15 with a first abutment surface 16d formed along the axial direction and a second abutment surface 16e formed along the circumferential direction.

[0033] As a result, with the convex portion 4 of the foundation pile 1 housed in the guide groove 16, the pile head portion 1a is housed in the guide tube 12A. In this state, when the first connecting jig 10 is rotated in the normal direction by the driving machine 30 relative to the foundation pile 1 (pile head portion 1a), the convex portion 4 is housed in the second groove 16b and abuts against the first abutment surface 16d, as shown in FIG. 3(c). Furthermore, when the driving machine 30 pulls up the foundation pile 1, the convex portion 4 abuts against the second abutment surface 16e (see FIG. 3(b)), and the foundation pile 1 can be supported via the first connecting jig 10. When the foundation pile 1 is driven, the end face of the pile head portion 1a abuts against the plate portion 13A.

[0034] 2. Regarding the drilling unit 100 and the second connecting jig 10B As shown in FIG. 7A(a) described later, the drilling unit 100 is a unit that excavates the ground G around the pile head 1a of the foundation pile 1 that is driven into the ground so that the pile head 1a is located deeper than the ground surface GL. The drilling unit 100 includes a drilling jig 40A (FIGS. 5A and 5B) that rotates around the axis of the foundation pile 1 as a rotation axis and excavates the ground G around the pile head 1a, and a guide jig 20 (FIG. 4) that is attached to the pile head 1a and guides the drilling jig 40A along the axis of the foundation pile 1. The drilling jig 40A is connected to the driving machine 30 via a second connecting jig 10B.

[0035] 2-1. Guide jig 20 The guide jig 20 is attached to the pile head 1a and guides the excavation jig 40A along the axis of the foundation pile 1 (see Figs. 7A(b) and (c)). The guide jig 20 includes a tubular attachment part 22 that is attached to the pile head 1a from above, and a guide part 21 that extends upward along the axis of the foundation pile 1 with the attachment part 22 attached to the pile head 1a and guides the excavation jig 40A.

[0036] In this embodiment, the guide part 21 and the mounting part 22 are fixed in the axial direction via an end plate 23. The end plate 23 is formed so as to cover the lower end opening of the guide part 21 and the upper end opening of the mounting part 22. A through hole 23a is formed in the center of the end plate 23. When the guide jig 20 is attached, it is possible to visually check through the through hole 23a whether the guide jig 20 is in the appropriate position relative to the pile head part 1a.

[0037] In this embodiment, the outer diameter of the mounting part 22 is approximately the same as or slightly smaller than the inner diameter D1 of the foundation pile 1, which allows the mounting part 22 to be inserted into the pile head part 1a along the axial direction. Furthermore, the guide part 21 is approximately the same as or slightly larger than the outer diameter D2 of the foundation pile 1, which allows the casing of the excavation jig 40A described later to be smoothly guided.

[0038] In this embodiment, as described above, as shown in Figure 7A(a), the guide tube 12A of the first connecting jig 10A forms a recess S1 in the ground G above the pile head 1a, the recess S1 having a diameter larger than the outer diameter D2 of the pile head 1a, so that the guide portion 21 and the mounting portion 22 of the guide jig 20 can be smoothly inserted into the excavation hole S2, as shown in Figure 7A(b).

[0039] The mounting part 22 has a guide portion 24 that guides the convex portion 4 of the pile head 1a from the lower end of the guide jig 20 along the axial direction of the guide jig 20. In this embodiment, since the mounting part 22 is cylindrical, the guide portion 24 is slit-shaped, but if the mounting part 22 is columnar, the guide portion 24 is groove-shaped. The guide portion 24 protrudes in the circumferential direction of the guide jig 20, so that hollowed-out portions 25A and 25B are formed on both sides in the circumferential direction. The hollowed-out portions 25A and 25B are formed continuously with the guide portion 24.

[0040] The hollowed-out portions 25A and 25B form restricting edges 26a and 26b on the edges of the guide portion 24 that restrict the rotation of the guide jig 20 around its axis, and also form locking edges 26d and 26e that lock onto the protrusion 4 so as to restrict the upward movement of the guide jig 20. When the mounting portion 22 is mounted inside the pile head portion 1a, the upper edge 26c of the guide portion 24 may abut against the protrusion 4, and the upper end of the pile head portion 1a may abut against the end plate 23.

[0041] Furthermore, a guide member 27 for guiding the guide jig 20 is attached to the mounting portion 22 from an opening 41a of the casing 41 of the drilling jig 40A described later into the inside of the casing 41. The guide member 27 is a linear member bent upward from a position facing the upper end edge of the guide jig 20 toward the axis of the guide jig 20. The guide member 27 is made of a steel wire or the like. By providing such a guide member 27, the drilling jig 40A can be guided in a direction along the axis of the guide jig 20. In particular, even if the length L1 of the guide portion 21 is shorter than the length L2 from the ground surface GL to the pile head 1a, the drilling jig 40A can be smoothly guided to the guide jig 20 during drilling as long as a part of the guide member 27 protrudes above the ground surface GL.

[0042] 2-2. About the excavation jig 40A As shown in Figures 5A, 5B(a) and (b), the excavation jig 40A comprises a cylindrical casing 41 having an opening 41a through which the guide portion 21 of the guide jig 20 is inserted from above, and an excavation blade 43 fixed to the casing 41 and having a cutting edge 43t inclined with respect to the rotation axis CL so as to scrape out soil and sand from the ground G by rotation in one direction around the rotation axis CL.

[0043] In this embodiment, the digging blade 43 is fixed to the outer peripheral surface of the casing 41 and is formed in a spiral shape so as to go around the rotation axis CL of the casing 41 multiple times (for example, twice). In this embodiment, the digging blade 43 is a double-spiral blade provided with two blades. Note that the number of digging blades 43 may be one, or three or more digging blades 43 may be provided. By providing multiple digging blades 43, the digging performance of the digging jig 40A can be improved.

[0044] Each excavation blade 43 has a spiral blade formed by a drilling wing 43a at the tip side of the casing 41 and a drilling wing 43b at the base end side. The cutting edge 43t of the excavation blade 43 formed in the circumferential direction of the drilling wing 43a at the tip side of the casing 41 is formed so that the distance between the rotation axis CL and the cutting edge 43t increases as the cutting edge 43t advances from the tip to the base end side of the casing 41. When the excavation jig 40A is viewed from below along the rotation axis CL, the cutting edge 43t is formed in a spiral shape.

[0045] 5A, in the cutting surface of the excavation blade 43 along the rotation axis CL, among the cutting edges 43t located on both sides of the rotation axis CL, the multiple cutting edges 43t located on each side are arranged on straight lines LA and LB. By linearly increasing the distance between the rotation axis CL and the cutting edges 43t as proceeding from the tip to the base end side of the casing 41, the multiple cutting edges 43t can be arranged on the straight line LA.

[0046] Furthermore, the straight line LA and the rotation axis CL are inclined at a predetermined angle, which is preferably in the range of 30° to 45°. The inclination angle can be set by setting the increasing rate of the distance from the tip of the casing 41 to the rotation axis CL and the cutting edge 43t to a constant.

[0047] Among the cutting edges 43t of the excavation blade 43, the cutting edges 43t formed in the circumferential direction of the excavation wing 43b at the base end side of the casing 41 are formed so that the distance between the rotation axis CL and the cutting edges 43t is the same. This allows the multiple cutting edges 43t on the base end side to be arranged on a straight line LB parallel to the rotation axis CL. Note that a convex portion 49 is provided on the outer peripheral surface of the casing 41 above the excavation blade 43, and is connected to the second connecting jig 10B as shown in FIG. 6.

[0048] 2-3. Regarding the second connecting jig 10B Specifically, the second connecting jig 10B has a tubular coupling portion 11B coupled to the driving machine 30, and a plate portion 13B fixed to the lower end of the coupling portion 11B and abutting against the upper end surface of the casing 41 of the excavation jig 40A. The second connecting jig 10B is provided with a cylindrical locking portion 12B having a cutout portion 17 formed therein that is locked by a protrusion 49 of the casing 41. The cutout portion 17 is formed so as to guide the protrusion 49 from the lower end of the locking portion 12B.

[0049] The cutout 17 extends further on both sides in the circumferential direction at the upper portion. As a result, the cutout 17 is formed with abutment edges 17a, 17b that abut against the protrusion 49 of the excavation jig 40A in the circumferential direction, and the torque of rotation in one direction (forward rotation) of the driving machine 30 and the torque of rotation in the other direction (reverse rotation) can be transmitted to the excavation jig 40A.

[0050] Furthermore, the cutout portion 17 is formed with abutment edges 17d, 17e that abut against the protrusion 49 of the drilling jig 40A in the axial direction when the drilling jig 40A is pulled out. This allows the driving machine 30 to move the drilling jig 40A together with the second connecting jig 10B in the up-down direction.

[0051] 3. Regarding the installation of foundation pile 1 and excavation of ground G A series of construction steps such as driving the foundation pile 1 and excavating the ground G will be described below with reference to FIG. 7A and FIG. 7B. First, the connecting portion 11A of the first connecting jig 10A is attached to the lifting head 32 of the driving machine 30, and the first connecting jig 10A is connected to the driving machine 30. Next, the foundation pile 1 is erected vertically on the ground GL, the pile head 1a of the foundation pile 1 is inserted into the guide tube 12A, and the locking portion 15 is locked to the convex portion 4 of the pile head 1a. The first connecting jig 10A is rotated slightly. As a result, the first connecting jig 10A is attached to the foundation pile 1. In this state, the foundation pile 1 is rotated around the rotation axis CL together with the first connecting jig 10A, and the foundation pile 1 is driven into the ground G. In this embodiment, as shown in FIG. 7A(a), the foundation pile 1 is driven into the ground so that the pile head 1a is positioned deeper than the ground GL.

[0052] In this state, as shown in Fig. 7A(b), the guide jig 20 is inserted into the recess S1, and the guide jig 20 is attached to the pile head 1a. Specifically, as shown in Fig. 4, the protrusion 4 formed on the pile head 1a is guided along the guide portion 24 formed on the attachment portion 22. Since the upper portion of the guide portion 24 is formed so as to protrude in the circumferential direction of the guide jig 20, the guide jig 20 can be rotated in the circumferential direction.

[0053] When the guide jig 20 is attached to the pile head 1a, the guide portion 21 of the guide jig 20 extends upward along the axis (rotation axis CL) of the foundation pile 1. In this state, the linear member that is the guide member 27 is bent upward from the position facing the upper end edge of the guide jig 20 (guide portion 21) toward the axis of the guide jig 20, so that the guide portion 21 of the guide jig 20 can be smoothly inserted from above into the opening 41a of the casing 41 of the excavation jig 40A. Note that, in a state in which the guide portion 21 protrudes from the ground surface GL when the guide jig 20 is attached to the pile head 1a, the guide member 27 does not need to be provided on the guide jig 20.

[0054] In this way, as shown in FIG. 7A(c), the excavation tool 40A connected to the second connection tool 10B can excavate the ground G around the pile head 1a, which is placed deeper than the ground GL, with the excavation tool 40A guided by the guide tool 20. In this embodiment, the excavation tool 40A of the guide tool 20 is pushed toward the ground G while rotating the excavation tool 40A in one direction (forward direction) around the rotation axis, with the axis of the foundation pile 1 as the rotation axis CL. This allows the excavation tool 40A around the pile head 1a to be excavated while scraping out the soil of the ground G with the excavation blade 43 fixed to the casing 41 and inclined with respect to the rotation axis CL. After excavation, the excavation tool 40A is pushed toward the ground G while rotating in the other direction (reverse direction) around the rotation axis CL, thereby compacting the bottom surface GB that forms a top-shaped space in the excavation hole S2 formed by excavation. In this way, compaction and removal of excess soil can be adjusted to suit the soil properties of ground G.

[0055] In addition, for convenience, Figure 7A (c) shows the drilling jig 40A detached from the second connecting jig 10B. However, during excavation, the drilling jig 40A is connected to the second connecting jig 10B from the start of excavation by the drilling jig 40A until the drilling jig 40A is pulled up from the ground G.

[0056] As a result, when the excavation jig 40A connected to the driving machine 30 is pulled upward after excavating the ground G from the state shown in FIG. 7A(c), the locking edge 26d (26e) of the guide portion 24 locks onto the convex portion 4 of the pile head 1a so as to restrict the upward movement of the guide jig 20. As a result, the excavation jig 40A can be separated from the guide jig 20 while the guide jig 20 is attached to the pile head 1a. In this way, even if the excavated soil or the like is clogged between the guide jig 20 and the excavation jig 40A, making it difficult to separate the guide jig 20 and the excavation jig 40A, they can be easily separated. After the excavation jig 40A has been pulled away from the guide jig 20, the worker grasps the guide member 27 protruding from the ground GL and rotates the guide jig 20 circumferentially to release the engagement between the locking edge portion 26d (26e) and the protrusion portion 4 of the pile head portion 1a, thereby allowing the guide jig 20 to be easily pulled away from the pile head portion 1a.

[0057] Next, as shown in FIG. 7B(a), for example, crushed stone GD is poured into the excavation hole S2 to compact the ground G around the pile head 1a. At this time, as shown in FIG. 7B(c), the excavation jig 40A may be rotated in the reverse direction to compact the crushed stone GD into a top shape, and the crushed stone GD may be rolled using a rammer 80. After that, the foundation of the building is placed so as to cover the pile head 1a from above. Note that concrete may be filled in place of the crushed stone GD. In this way, the vertical and horizontal bearing capacity of the foundation pile 1 can be increased, and the horizontal and vertical displacement of the pile head 1a can be reduced.

[0058] In particular, when a bladed steel pipe pile is used as the foundation pile 1, the tip blades 3 disturb the ground G around the steel pipe pile during driving, so the peripheral friction around the foundation pile 1 is very small, but by using the excavation jig 40A to push the existing ground into the underlying ground, the ground around the foundation pile 1 is compacted and the peripheral friction force of the pile increases. Furthermore, by compacting the ground around the pile head 1a of the foundation pile 1, the vertical bearing capacity of the reinforced part of the top-shaped pile head 1a is improved compared to when the soil is removed and then cast, and the bearing capacity of the ground G in the surrounding unreinforced part is also improved.

[0059] In this way, the density of the ground G increases, and loosening of the ground G due to rainfall, etc. By providing a top-shaped reinforcing portion in the compacted ground G in this way, the bearing capacity of the foundation pile 1 can be ensured with a reinforcing portion having a small length and diameter, allowing for economical and environmentally friendly construction.

[0060] Second Embodiment A drilling jig 40B according to a second embodiment will be described below with reference to Figures 8A and 8B. In the drilling jig 40B, a casing 41 has a cylindrical connecting portion 41A connected to the second connecting jig 10B, and a cylindrical main body portion 41B having a larger diameter than the connecting portion 41A. A protrusion 49 that is engaged with the second connecting jig 10B is formed on the outer circumferential surface of the connecting portion 41A.

[0061] An umbrella-shaped portion 44 having a shape of a side surface of a truncated cone that widens from the tip side toward the base end side of the casing 41 is attached to the outer peripheral surface of the tip side of the main body portion 41B of the casing 41. The umbrella-shaped portion 44 has a predetermined thickness, and is formed with an outer peripheral surface 44a and an inner peripheral surface 44b of a truncated cone. With a plurality of reinforcing ribs 45B spanning between the inner peripheral surface 44b of the umbrella-shaped portion 44 and the outer peripheral surface of the casing 41, an internal space E is formed in the umbrella-shaped portion 44.

[0062] In this embodiment, the tip of the umbrella-shaped portion 44 coincides with the opening 41a of the casing 41. The umbrella-shaped portion 44 is formed with a plurality of (e.g., three) excavation blades 43A. In this embodiment, the excavation blades 43A are inclined in the circumferential direction relative to the outer circumferential surface 44a of the umbrella-shaped portion 44 and rise at an acute angle (see, for example, FIG. 8B(b)). A support rib 45A is attached by welding to each excavation blade 43A so that the excavation blade is supported by the umbrella-shaped portion 44 during excavation.

[0063] 8B(a), the cutting edge 43t of the excavation blade 43A is formed along the direction of the generatrix LC of the truncated cone that forms the outer circumferential surface 44a of the umbrella-shaped portion 44. Furthermore, the umbrella-shaped portion 44 is formed at the base end of the excavation blade 43A with a rectangular through-hole 46A that allows the soil crushed by the excavation blade 43A to pass through to the inner circumferential surface 44b of the umbrella-shaped portion 44.

[0064] Each digging blade 43A may be formed by forming slits on three sides of a rectangular through-hole 46A in a truncated cone shell corresponding to the umbrella-shaped portion 44, and then bending the portion surrounded by the slits so that it rises from the outer circumferential surface 44a. This allows the digging blade 43A and the through-hole 46A to be formed in the umbrella-shaped portion 44 at the same time.

[0065] According to the excavation jig 40B of this embodiment, the excavation blade 43A rises at an incline in the circumferential direction with respect to the outer peripheral surface 44a of the umbrella-shaped portion 44, and the cutting edge 43t is formed along the direction of the generatrix LC of the truncated cone. As a result, the excavation jig 40B can be rotated in one direction (positive direction) around the rotation axis CL while being pushed into the ground G, thereby efficiently excavating the ground G around the pile head 1a of the foundation pile 1. The umbrella-shaped portion 44 has a through hole 46A formed at the base end of the excavation blade 43A, so that the soil generated by excavation can pass through the through hole 46A to the inner peripheral surface 44b side of the umbrella-shaped portion 44 and be discharged above the excavation blade 43A.

[0066] In particular, because the cutting edge 43t of the excavation blade 43A is formed along the direction of the generatrix LC of the truncated cone, the ground G around the pile head 1a can be excavated while the excavation jig 40B is pressed into the ground more efficiently. After excavation, the bottom surface GB of the excavation hole S2 formed by excavation can be compacted by pressing the excavation jig 40B into the ground G while rotating the excavation jig 40B in the other direction (reverse direction) around the rotation axis CL.

[0067] Third Embodiment A drilling jig 40C according to a third embodiment will be described below with reference to Figures 9A to 9C. In the drilling jig 40C, the drilling blade 43C is a plate-like member fixed to the outer peripheral surface of the tip side of the casing 41 at an angle with respect to the rotation axis CL, and has a substantially sector shape. In this embodiment, a plurality of (for example, three) drilling blades 43C are fixed to the outer peripheral surface of the tip side of the casing 41 at intervals in the circumferential direction of the casing 41.

[0068] In the excavation jig 40C, a cylindrical frame 47 with the rotation axis CL as its axis is fixed to the casing 41 via the excavation blade 43C. As shown in FIG. 9A, the excavation blade 43C is disposed between the inner peripheral surface of the frame 47 and the outer peripheral surface of the casing 41 so that the cutting edge 43t at the tip side of the casing 41 is exposed. Between the excavation blades 43C, 43C adjacent in the circumferential direction, a gap 46B is formed that allows the soil generated by the excavation blade 43C to pass from below the frame 47 to the internal space E of the frame 47. In this embodiment, the cutting edge 43t is inclined at the same inclination angle around the rotation axis CL. As shown in FIG. 9A, in a top view of the excavation jig 40C, the multiple excavation blades 43C are disposed around the rotation axis CL so as to cover the internal space E of the frame 47.

[0069] According to this embodiment, the excavation blade 43C is a plate-shaped member fixed to the outer peripheral surface of the tip side of the casing 41 at an angle with respect to the rotation axis CL of the casing 41, and a plurality of the excavation blades 43C are fixed to the outer peripheral surface of the tip side of the casing 41 at intervals in the circumferential direction of the casing 41. As a result, the excavation tool 40C can be rotated in one direction (positive direction) around the rotation axis CL while pushing the excavation tool 40C into the ground G, thereby efficiently excavating the ground G around the pile head 1a of the foundation pile 1. Since a gap 46B is formed between the adjacent excavation blades 43C, 43C, the soil generated by excavation can be passed from the bottom of the frame body to the internal space E of the frame body 47 through the gap 46B between the excavation blades 43C, 43C and discharged above the excavation blade 43C.

[0070] In particular, the drilling blade 43C is positioned between the inner surface of the frame body 47 and the outer surface of the casing 41 so that the cutting edge 43t at the tip side of the casing 41 is exposed, so that the ground G around the pile head 1a can be excavated while the drilling jig 40C is pushed into the ground G more efficiently.

[0071] Since the outer peripheral surface of the cylindrical frame 47 moves along the side wall surface GC of the excavated hole S2 in the excavated ground G, it is possible to prevent the side wall surface GC of the excavated hole S2 around the pile head 1a formed after excavation from collapsing. Since the soil generated by excavation exists in the internal space E of the cylindrical frame 47 and above it, when the excavation jig 40C is pulled up from the ground G, it is possible to efficiently discharge the soil from the excavated hole S2 while preventing the side wall surface GC of the excavated hole S2 around the pile head 1a formed after excavation from collapsing. In addition, after excavation, the bottom surface GB of the excavated hole S2 formed by excavation can be compacted by pushing the excavation jig 40C toward the ground G while rotating the excavation jig 40C in the other direction (reverse direction) around the rotation axis CL.

[0072] 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 as described in the claims. [Explanation of symbols]

[0073] 1: foundation pile, 1a: pile head, 4: convex portion (locking convex portion), 20: guide jig, 21: guide portion, 22: mounting portion, 24: guide portion, 26d, 26e: locking edge portion, 27: guide member, 40A to 40C: excavation jig, 41: casing, 43, 43A, 43B: excavation blade, 43t: blade tip, 44: umbrella-shaped portion, 47: frame body, 100: excavation unit, CL: rotation axis (axis line), E: internal space, G: ground, GL: ground surface

Claims

1. A drilling unit that excavates the ground around a pile head of a foundation pile that is driven into the ground so that the pile head is located deeper than the ground surface, The drilling unit comprises: An excavation tool that rotates about the axis of the foundation pile as a rotation axis and excavates the ground around the pile head; A guide jig is attached to the pile head and guides the excavation jig along the axis of the foundation pile. The guide jig is A mounting portion that is attached to the pile head from above the pile head; A guide portion that extends upward along the axis of the foundation pile and guides the excavation jig when the mounting portion is attached to the pile head, The drilling tool is a cylindrical casing having an opening through which the guide portion is inserted from above the guide portion; A drilling unit comprising: a digging blade fixed to the casing and having a cutting edge inclined relative to the rotation axis so as to scrape out soil and sand from the ground by rotation in one direction around the rotation axis.

2. The pile head is formed with a locking protrusion that is locked to the guide jig, the mounting portion has a guide portion that guides the locking protrusion from a lower end of the guide jig along an axial direction of the guide jig, The drilling unit described in claim 1, characterized in that the edge of the guide portion is formed with a locking edge portion that engages with the locking protrusion so as to limit the upward movement of the guide jig by the guide portion extending circumferentially around the guide jig.

3. a guide member is attached to the mounting portion to guide the guide jig from an opening of the casing to an inside of the casing, 2. The drilling unit according to claim 1, wherein the guide member is a linear member bent upward from a position opposite the upper end edge of the guide jig toward the axis of the guide jig.

4. The excavation blade is fixed to the outer peripheral surface of the casing and is formed in a spiral shape so as to rotate multiple times around the rotation axis of the excavation jig, The drilling unit described in claim 1, characterized in that the cutting edge of the drilling blade, which is formed circumferentially at the tip side of the casing, is formed so that the distance between the rotation axis and the cutting edge increases as one moves from the tip of the casing toward the base end.

5. The drilling jig is attached to the outer peripheral surface of the tip side of the casing and includes an umbrella-shaped portion having a shape of a side surface of a truncated cone expanding from the tip side of the casing toward the base end side, The digging blade is inclined in the circumferential direction relative to the outer circumferential surface of the umbrella-shaped portion, The cutting edge is formed along the direction of the generatrix of the truncated cone, The excavation unit according to claim 1, characterized in that the umbrella-shaped portion is formed with a through hole at the base end of the excavation blade, which allows the soil to pass through to the inner surface side of the umbrella-shaped portion.

6. The excavation blade is a plate-shaped member fixed to the outer peripheral surface of the tip side of the casing at an angle with respect to the rotation axis of the excavation jig, and is fixed to the outer peripheral surface of the tip side of the casing at intervals in the circumferential direction of the casing, The excavation jig has a cylindrical frame with the rotation shaft as its axis, and is fixed to the casing via the excavation blade, The excavation blade is disposed between the inner circumferential surface of the frame body and the outer circumferential surface of the casing so that the cutting edge portion on the tip side of the casing is exposed, The excavation unit according to claim 1 , characterized in that a gap is formed between adjacent excavation blades to allow the soil and sand to pass from below the frame body into the internal space of the frame body.

Images