Enlarging bottom earth boring bucket, adapter of enlarging bottom earth boring bucket and construction method of bottom enlarged hole

Abstract

To provide an enlarging bottom earth boring bucket capable of enlarging a bottom part of a vertical hole bored in the ground even when the bottom part of the vertical hole is formed of a hard layer while reducing the time necessary for enlarging the diameter.SOLUTION: A boring bit mount body 13 mounted on an enlarging width blade 5 rotating around a first center axis C1 as a rotational center to enlarge a diameter of a bottom part 19 of a vertical hole 17 bored in the ground 15 comprises: a body part 21 for a boring bit mount body supported on the enlarging width blade 5 so as to rotate around a second central axis C2 as a rotational center; and a plurality of boring bit mount parts 23 arranged on the body part 21 for the boring bit, on which a first boring bit 25 is installed.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a bottom-expanded earth drill bucket, an adapter for the bottom-expanded earth drill bucket, and a method for constructing a bottom-expanded hole. [Background technology]

[0002] Conventionally, a center trench excavator 301 as shown in Fig. 8 has been known (see Patent Document 1). The center trench excavator 301 is designed to be mounted inside an excavation casing 303 used in the all-casing construction method.

[0003] The inner trench excavator 301 comprises a drive unit 305 that is detachably fixed to the inside of an excavation casing 303, and a wide-bottom bucket 307 that is interlocked with the drive unit 305. The drive unit 305 comprises a casing body 309, a drive shaft 311, a rotary drive unit 313, a feeder device 315, and a chuck device 317.

[0004] The drive shaft 311 is arranged in the center of the casing body 309 so as to be rotatable and movable up and down, and the bottom-expanding bucket 307 is connected to the lower end of the drive shaft 311. The rotation drive unit 313 drives the drive shaft 311 to rotate. The feeder device 315 moves the drive shaft 311 up and down. The chuck device 317 presses against the inner wall surface of the excavation casing 303 to fix the inner excavation machine 301 itself to the inner wall surface of the excavation casing 303.

[0005] The bottom expansion bucket 307 is configured to expand the diameter of the bottom of a vertical hole (for example, a cylindrical vertical hole) that is not surrounded by the excavation casing 303 into a truncated cone shape. An excavation bit 321 is integrally provided on the expansion blade 319. Then, by expanding the expansion blade 319 while rotating, the ground is excavated by the excavation bit 321, and the diameter of the bottom of the vertical hole is expanded into a truncated cone shape. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-114543 Summary of the Invention [Problem to be solved by the invention]

[0007] Incidentally, when the ground is soft, ordinary soil and sand, it is easy to enlarge the diameter of the bottom of the vertical hole using a conventional inner excavator 301. However, there is a hard layer (gravel, boulders, clay, etc.) below the soft, ordinary soil and sand, and in many cases the diameter of the bottom of the vertical hole must be enlarged in the hard layer.

[0008] When attempting to enlarge the bottom of a vertical hole using a conventional inner trench drilling machine 301 in a hard layer of ground, the drilling bit 321 is fixed to the enlargement wing 319, so it may take a long time to enlarge the hole, or it may not be possible to enlarge the hole at all.

[0009] To provide a device that enables the diameter of a vertical hole dug in the ground to be expanded even if the bottom of the vertical hole is formed of a hard layer, and that can shorten the time required for the expansion. [Means for solving the problem]

[0010] A drilling bit installation body according to one embodiment of the present invention is a drilling bit installation body that is installed on an expansion wing that rotates around a first central axis as the center of rotation in order to expand the diameter of the bottom of a vertical hole dug in the ground, and has a drilling bit installation body main body supported on the expansion wing so as to rotate around a second central axis as the center of rotation, and a plurality of drilling bit installation parts that are provided on the drilling bit installation body main body and on which a first drilling bit is installed.

[0011] In addition, in a drilling bit installation body according to an aspect of the present invention, the multiple drilling bit installation portions are arranged along a spiral extending on the outer periphery of the drilling bit installation body main body, and there are multiple spirals, and the multiple spirals are arranged in the circumferential direction of the drilling bit installation body main body.

[0012] In addition, in a drilling bit installation body according to an aspect of the present invention, the drilling bit installation body main body is configured with a pair of annular members and a plurality of helical members, the pair of annular members having central axes that coincide with each other and are spaced a predetermined distance apart in the extension direction from their central axes, each of the plurality of helical members having one longitudinal end joined to one of the pair of annular members and the other longitudinal end joined to the other of the pair of annular members, the plurality of helical members being arranged in positions that equally distribute the circumference of the annular member, and the plurality of drilling bit installation portions being provided on each of the plurality of helical members and being arranged at predetermined intervals in the extension direction of the helical members.

[0013] The expanded-bottom earth drill bucket according to one embodiment of the present invention is composed of a stabilizer and a pair of arm-shaped members, wherein a first arm-shaped member, which is one of the pair of arm-shaped members, is rotatably engaged with the stabilizer at its upper end in the longitudinal direction, and a second arm-shaped member, which is the other of the pair of arm-shaped members, is rotatably engaged with the stabilizer at its upper end in the longitudinal direction.The expanded-bottom earth drill bucket has an expansion wing on which a drilling bit installation body installation section on which the drilling bit installation body is installed is provided, and an expansion wing drive section that rotates the pair of arm-shaped members relative to the stabilizer.

[0014] In addition, the expanded-bottom earth drill bucket according to this aspect of the present invention has a expanded-bottom earth drill bucket fixing portion that is fixed to the drilling casing that forms the wall of the vertical hole, and a expanded-bottom earth drill bucket rotation support portion that is supported by the expanded-bottom earth drill bucket fixing portion and that drives the expansion blades to rotate relative to the drilling casing when the expanded-bottom earth drill bucket fixing portion is fixed to the drilling casing, or that prevents the expansion blades from rotating relative to the drilling casing when the expanded-bottom earth drill bucket fixing portion is fixed to the drilling casing.

[0015] In addition, the bottom-expanding earth drill bucket according to this embodiment of the present invention is equipped with a second drilling bit provided at the lower end of the expansion wing, and when drilling the vertical hole, the expansion wing on which the first drilling bit is installed is closed, the bottom-expanding earth drill bucket fixing part is fixed to the drilling casing, and the bottom-expanding earth drill bucket rotating support part prevents the expansion wing from rotating relative to the drilling casing, and the drilling casing is moved downward as it rotates, and after drilling of the vertical hole is completed, the bottom-expanding earth drill bucket fixing part is fixed to the drilling casing, and the expansion wing is rotated relative to the drilling casing by the bottom-expanding earth drill bucket rotating support part while the expansion wing is gradually opened by the expansion wing drive part.

[0016] The bottom-expanding earth drill bucket according to an embodiment of the present invention is composed of a stabilizer and a plurality of arm-shaped members, wherein a first arm-shaped member, which is one of the pair of arm-shaped members, is rotatably engaged with the stabilizer at its upper end in the longitudinal direction, and a second arm-shaped member, which is the other of the pair of arm-shaped members, is rotatably engaged with the stabilizer at its upper end in the longitudinal direction, a first drilling bit is installed on the outer periphery, a second drilling bit is installed on the bottom, and the bottom-expanding earth drill bucket rotates around a first central axis, and the plurality of arm-shaped members are connected to the The drill bucket has an expansion blade drive unit that rotates relative to the stabilizer, an expansion-bottom earth drill bucket fixing unit that is fixed to a drilling casing that forms the wall of a vertical hole dug in the ground, and an expansion-bottom earth drill bucket rotation support unit that is supported by the expansion-bottom earth drill bucket fixing unit and drives the expansion blade to rotate relative to the drilling casing when the expansion-bottom earth drill bucket fixing unit is fixed to the drilling casing, or prevents the expansion blade from rotating relative to the drilling casing when the expansion-bottom earth drill bucket fixing unit is fixed to the drilling casing.

[0017] The adapter for an expanded-bottom earth drill bucket according to one embodiment of the present invention is an adapter for an expanded-bottom earth drill bucket that connects a rotary propulsion body and a stabilizer of the expanded-bottom earth drill bucket, and comprises an adapter main body, a first fitting portion that is integrally formed with the adapter main body on the upper side of the adapter main body and fits into the fitting portion of the rotary propulsion body to transmit the rotational force generated by the rotary propulsion body to the adapter main body, a second fitting portion that is integrally formed with the adapter main body on the lower side of the adapter main body and fits into the fitting portion of the stabilizer to transmit the rotational force generated by the rotary propulsion body to the stabilizer, and a reinforcing member whose one end is integrally joined to the adapter main body and whose other end is integrally joined to the stabilizer.

[0018] A method for constructing a bottom-expanded hole according to one embodiment of the present invention is a method for constructing a bottom-expanded hole using the bottom-expanded earth drill bucket, in which a second drilling bit is provided at the lower end of the expansion wing, and the expansion wing on which the first drill bit is provided is closed, the expansion wing fixing part is fixed to the drilling casing, and the expansion wing is prevented from rotating relative to the drilling casing by the bottom-expanded earth drill bucket rotation support part, and the drilling casing is rotated and moved downward to excavate the ground to create a vertical hole (a vertical hole excavation process), and after the excavation of the vertical hole in the vertical hole excavation process is completed, the expansion wing fixing part is fixed to the drilling casing, and the expansion wing is rotated relative to the drilling casing by the bottom-expanded earth drill bucket rotation support part while the expansion wing is gradually opened by the expansion wing drive part, thereby expanding the diameter of the bottom of the vertical hole. [Effects of the Invention]

[0019] According to the present invention, when expanding the diameter of the bottom of a vertical hole dug in the ground, it is possible to expand the diameter even if the bottom of the vertical hole is formed of a hard layer, and it is also possible to shorten the time required for expanding the diameter. [Brief explanation of the drawings]

[0020] [Figure 1] FIG. 1 is a front view of a bottom-widening earth drill bucket according to an embodiment of the present invention, showing the widening wing in a closed state (widening wing closed state). [Figure 2] FIG. 1 is a front view of a bottom-widening earth drill bucket according to an embodiment of the present invention, showing the widening wing in its maximum open state (widening wing maximum opening state). [Figure 3] FIG. 1 is a front view of the ground, a drilling casing, an expanded-bottom earth drill bucket according to an embodiment of the present invention, and a vertical hole with an expanded bottom. [Figure 4] 4A and 4B are views showing a drilling bit installing body according to an embodiment of the present invention, and FIG. 4B is a view taken along the arrow IVB in FIG. [Figure 5] 1 is a diagram showing a schematic diagram of the operation of the bottom-expanding earth drill bucket according to an embodiment of the present invention when expanding the diameter of the bottom of a vertical hole. [Figure 6] FIG. 4(a) is a diagram schematically showing the bottom-expanded earth drill bucket shown in FIGS. 1 to 3, and FIG. 4(b) is a diagram schematically showing a bottom-expanded earth drill bucket according to a modified example. [Figure 7] 6A is a view showing an adapter and the like used in the bottom-expanding earth drill bucket according to the embodiment of the present invention, and FIG. 6B is a view taken along the line VIIB-VIIB in FIG. [Figure 8] FIG. 1 is a diagram showing a conventional inner trench excavator. DETAILED DESCRIPTION OF THE INVENTION

[0021] A bottom-expanding earth drill bucket (bottom-expanding bucket) 1 according to an embodiment of the present invention is configured to include a stabilizer 3, a width-expanding blade 5, and a width-expanding blade drive unit 7, as shown in FIGS.

[0022] The stabilizer 3 has a roughly short cylindrical outer shape. The stabilizer 3 and the spread wing 5 rotate around a first central axis C1. The central axis of the stabilizer 3 coincides with the first central axis C1. The first central axis C1 extends in the vertical direction, but the first central axis C1 may extend in a direction oblique to the vertical direction or in the horizontal direction.

[0023] The spreader wing 5 is configured with a plurality of (for example, a pair of) arm-shaped members 9 (9A, 9B). One of the pair of arm-shaped members 9, a first arm-shaped member 9A, is formed in a generally linear rod shape. The first arm-shaped member 9A is rotatably engaged with the stabilizer 3 at its upper end in the longitudinal direction.

[0024] The second arm member 9B, which is the other of the pair of arm members 9, is formed in a similar shape to the first arm member 9A. The second arm member 9B also rotatably engages with the stabilizer 3 at its upper end in the longitudinal direction.

[0025] Further, the expansion wing 5 (arm-shaped members 9A, 9B) is provided with a drilling bit placing body installation portion 11 on which a drilling bit placing body 13 (see FIG. 4, etc.) is installed. The drilling bit placing body 13 will be described in detail later.

[0026] The first arm-shaped member 9A engages with the stabilizer 3 near the outer periphery of the stabilizer 3, and the second arm-shaped member 9B engages with the stabilizer 3 at a location near the outer periphery of the stabilizer 3 that is different from the first arm-shaped member 9A. The first arm-shaped member 9A and the second arm-shaped member 9B extend downward from the stabilizer 3.

[0027] 2, the rotation center axis C3 of the first arm-shaped member 9A relative to the stabilizer 3 and the rotation center axis C4 of the second arm-shaped member 9B relative to the stabilizer 3 are parallel to each other and extend in a substantially horizontal direction. The second arm-shaped member 9B is disposed symmetrically to the first arm-shaped member 9A with respect to the first center axis C1.

[0028] The blade expansion drive unit 7 causes the pair of arm-shaped members 9 (9A, 9B) to rotate about the rotation center axes C3 and C4 relative to the stabilizer 3. Furthermore, the blade expansion drive unit 7 causes the first arm-shaped member 9A and the second arm-shaped member 9B to rotate simultaneously relative to the stabilizer 3 in a manner symmetrical with respect to the first center axis C1.

[0029] The state in which the first arm-shaped member 9A and the second arm-shaped member 9B extend downward from the stabilizer 3 parallel to the first central axis C1 is defined as the closed state of the spreader wing 5 (see FIG. 1). In the closed state of the spreader wing 5, the first arm-shaped member 9A and the second arm-shaped member 9B extend from the stabilizer 3, for example, directly downward.

[0030] The state in which the first arm-shaped member 9A extends from the stabilizer 3 in a direction intersecting the first central axis C1, and the second arm-shaped member 9B extends from the stabilizer 3 in a direction intersecting the first central axis C1, is defined as the open state of the spreader wing 5. In the open state of the spreader wing 5, the distance (horizontal distance) between the first arm-shaped member 9A and the second arm-shaped member 9B gradually increases toward the lower sides of the first arm-shaped member 9A and the second arm-shaped member 9B.

[0031] The open state of the expansion wing 5 refers to any state other than the closed state of the expansion wing 5. In the open state of the expansion wing 5, the intersecting angle between the extension direction of the first arm-shaped member 9A and the first central axis C1 gradually increases as the opening angle of the expansion wing 5 increases. Furthermore, the intersecting angle between the extension direction of the second arm-shaped member 9B and the first central axis C1 gradually increases.

[0032] The state in which the angle of intersection between the extension direction of the first arm-shaped member 9A and the first central axis C1 is at its maximum value and the angle of intersection between the extension direction of the second arm-shaped member 9B and the first central axis C1 is at its maximum value is considered to be the maximum open state of the expansion wing 5 (see Figures 2, 3, and 6).

[0033] When the expansion wing 5 is in the maximum open state, the angle of intersection between the extension direction of the first arm-shaped member 9A (the portion extending downward from the rotation center axis C3) and the first center axis C1 is approximately 20°. When the expansion wing 5 is in the maximum open state, the angle of intersection between the extension direction of the second arm-shaped member 9B (the portion extending downward from the rotation center axis C4) and the first center axis C1 is also approximately 20°. Note that the angle of "20°" is merely an example. By opening the expansion wing 5 to the maximum open state, the diameter of the bottom 19 of the vertical hole 17 dug in the ground 15 is completed.

[0034] The drilling bit installation body 13 will be described in detail with reference to Figs.

[0035] The drilling bit installation body 13 is installed and used on the drilling bit installation body installation portion 11 (see Figures 1, 2, etc.) of the expansion wing 5 (arm-shaped member 9). The expansion wing 5 rotates around a first central axis C1 as the center of rotation in order to expand the diameter of the bottom 19 of a vertical hole (for example, a cylindrical vertical hole) 17 dug in the ground 15. The central axis of the vertical hole 17 and the first central axis C1 are aligned with each other.

[0036] A plurality of drilling bit placing body installation sections 11 are provided on the expansion wing 5. The plurality of drilling bit placing body installation sections 11 are arranged at predetermined intervals in the extension direction (longitudinal direction) of the arm-shaped member 9A (arm-shaped member 9B) on the outer side (opposite side from the first central axis C1) of the arm-shaped member 9A (arm-shaped member 9B). A drilling bit placing body 13 is removably installed on each of the plurality of drilling bit placing body installation sections 11.

[0037] The drilling bit placing body 13 is provided with a drilling bit placing body main body 21 and a plurality of drilling bit placing portions 23 .

[0038] The drilling bit placing body main body 21 is supported by the expansion wing 5 on the outer side of the expansion wing 5 (the side opposite to the first central axis C1). To explain further, the drilling bit placing body main body 21 is installed on the arm-shaped member 9 via a drilling bit placing body support 24. The drilling bit placing body support 24 is installed integrally with the arm-shaped member 9 by fasteners such as bolts.

[0039] The drilling bit placing body main body 21, which is supported by the expansion wing 5 (arm-shaped member 9), is configured to rotate relative to the expansion wing 5 around the second central axis C2 as the center of rotation. The second central axis C2 extends, for example, in a direction parallel to the longitudinal direction of the expansion wing 5 (arm-shaped member 9). More specifically, the drilling bit placing body main body 21 is configured to rotate relative to the drilling bit placing body support body 24, which is integrally provided on the arm-shaped member 9, around the second central axis C2 as the center of rotation.

[0040] The longitudinal direction of the expansion wing 5 (the longitudinal direction of the arm-shaped member 9; the extension direction of the second central axis C2) coincides with the extension direction of the first central axis C1 when the drilling bit installation body 13 is installed on the expansion wing 5 and the expansion wing 5 is closed. When the expansion wing 5 opens with the drilling bit installation body 13 installed on the expansion wing 5, the angle of intersection between the longitudinal direction of the expansion wing 5 and the first central axis C1 gradually increases as the expansion wing 5 opens.

[0041] The drilling bit installing body main body 21 is roughly formed in a columnar or cylindrical shape, and the central axis of this column, circle, etc. and the second central axis C2 coincide with each other.

[0042] Each of the plurality of drilling bit setting portions 23 is provided on the outer periphery of the drilling bit setting body main body 21. A drilling bit (first drilling bit) 25 is integrally set on each of the plurality of drilling bit setting portions 23.

[0043] The bottom 19 of the vertical hole 17 excavated in the ground 15 (see Figure 3) is expanded by scraping the ground 15 with a first drilling bit 25 provided in the drilling bit installation section 23 of the drilling bit installation body main body 21.

[0044] When the ground 15 is being excavated, as shown in Figure 5 etc., the expansion wing 5 rotates (spins) in one direction, for example, with the first central axis C1 as the center of rotation (see arrow A1). Also, when the ground 15 is being excavated, the drilling bit installation body 13 rotates (spins) in one direction (the opposite direction to the expansion wing 5) with the second central axis C2 as the center of rotation (see arrow A2). Furthermore, when the ground 15 is being excavated, it can be said that the drilling bit installation body 13 revolves around the first central axis C1, with the first central axis C1 as the center of rotation.

[0045] The shape of the bottom 19 of the enlarged vertical hole 17 is a truncated cone with a diameter at the bottom that is larger than the diameter at the top, as shown in Figure 3. The central axis of the truncated cone of the bottom 19 of the enlarged vertical hole 17 coincides with the central axis of the cylindrical vertical hole 17, and the diameter of the top of the truncated cone of the bottom 19 of the enlarged vertical hole 17 coincides with the diameter of the cylindrical vertical hole 17.

[0046] 4, the plurality of drilling bit setting portions 23 are arranged at predetermined intervals along a spiral (first spiral). The first spiral extends on the outer periphery of the drilling bit setting body main body 21. In other words, the first spiral extends so as to wrap around the outer periphery of the drilling bit setting body main body 21.

[0047] There are a plurality of (for example, four) first spirals. The plurality of first spirals are arranged at predetermined intervals in the circumferential direction of the drilling bit installation body main body 21. The central axis of the first spiral coincides with the second central axis C2.

[0048] When each of the multiple first drilling bits 25 is installed in each of the multiple drilling bit installation sections 23, each of the cutting edges 27 of the multiple first drilling bits 25 is aligned along each of the multiple second spirals.

[0049] The central axis of the second spiral also coincides with the second central axis C2. Each of the second spirals extends outside and parallel to each of the first spirals.

[0050] The number of turns of the first spiral and the second spiral is, for example, less than or equal to 1 and greater than or equal to 0.1. More specifically, the number of turns of the first spiral and the second spiral is about 1 / 4.

[0051] Furthermore, the number of the first spiral is approximately equal to the reciprocal of the number of turns of the first spiral. For example, if the number of turns of the first spiral is "1 / 4," the number of turns of the first spiral is 4. As will be understood, the number of turns of the first spiral and the number of turns of the second spiral are equal to each other, and the number of turns of the first spiral and the number of turns of the second spiral are equal to each other.

[0052] The drilling bit installation body main body 21 is configured to include a pair of annular members (for example, circular ring-shaped members) 29 (29A, 29B) and a plurality of (for example, four) helical members 31. The number of helical members 31 matches the number of the first helices (second helices), and the helical members 31 extend along the first helices and the second helices.

[0053] The central axes of the pair of annular members 29 (29A, 29B) coincide with each other and are spaced a predetermined distance apart in the extension direction from these central axes. The central axes of the pair of annular members 29 (29A, 29B) coincide with the second central axis C2. The height dimension of the annular member 29B (the dimension in the extension direction of the second central axis C2) is greater than the height dimension of the annular member 29A.

[0054] Each of the plurality of spiral members 31 has one longitudinal end (first end) joined to one annular member (first annular member) 29A of the pair of annular members 29. Furthermore, each of the plurality of spiral members 31 has the other longitudinal end (second end) joined to the other annular member (second annular member) 29B of the pair of annular members 29. Furthermore, the plurality of spiral members 31 are arranged at positions that equally distribute the circumference of the annular member 29.

[0055] The plurality of drilling bit setting portions 23 are provided on each of the plurality of helical members 31, and are arranged at predetermined intervals in the direction in which the helix of the helical member 31 extends.

[0056] As shown in FIG. 3, the bottom-expanded earth drill bucket 1 is provided with a bottom-expanded earth drill bucket fixing portion 33 and a bottom-expanded earth drill bucket rotation support portion 35.

[0057] The bottom-expanding earth drill bucket fixing portion 33 is inserted into a drilling casing (e.g., a cylindrical steel pipe) 39 that forms the wall of the vertical hole 17 (the wall that separates the ground 15 from the space 37 of the vertical hole 17) and is fixed to the drilling casing 39.

[0058] The bottom-expanded earth drill bucket rotation support part 35 is supported by the bottom-expanded earth drill bucket fixing part 33. With the bottom-expanded earth drill bucket fixing part 33 fixed to the drilling casing 39, the bottom-expanded earth drill bucket rotation support part 35 drives the stabilizer 3 and the widening blade 5 to rotate relative to the drilling casing 39, for example, hydraulically. Alternatively, with the bottom-expanded earth drill bucket fixing part 33 fixed to the drilling casing 39, the bottom-expanded earth drill bucket rotation support part 35 prevents the stabilizer 3 and the widening blade 5 from rotating relative to the drilling casing 39.

[0059] The fixed state is a state in which the bottom-expanding earth drill bucket fixing portion 33 is fixed to the drilling casing 39 and prevents the stabilizer 3 and the spreader blade 5 from rotating relative to the drilling casing 39. In this fixed state, the spreader blade 5 and the stabilizer 3 are fixed to the drilling casing 39 and are integrated with the drilling casing 39.

[0060] The bottom-widening earth drill bucket 1 is also configured to include a second drilling bit 41 provided at the lower end of the widening wing 5.

[0061] The vertical hole 17 is excavated as follows. The expansion wing 5 is closed. A first drilling bit 25 is installed on the expansion wing 5 using the drilling bit installation body 13. When excavating the vertical hole 17, the bottom-expanding earth drill bucket fixing part 33 is fixed to the drilling casing 39, and the bottom-expanding earth drill bucket rotation support part 35 prevents the expansion wing 5 from rotating relative to the drilling casing 39. Furthermore, the drilling casing 39 installed on the earth drill 43 is rotated by the earth drill 43 and moves downward.

[0062] After the drilling of the vertical hole 17 is completed, the rotation of the drilling casing 39 by the earth drill 43 is stopped, and the downward movement of the drilling casing 39 is stopped. As a result, the drilling casing 39 and the ground 15 are integrated.

[0063] After the drilling of the vertical hole 17 is completed, the diameter of the bottom 19 of the vertical hole 17 is expanded as follows: The bottom-expanding earth drill bucket fixing part 33 is fixed to the drilling casing 39. The bottom-expanding earth drill bucket rotation support part 35 rotates the expander blades 5 relative to the drilling casing 39, while the expander blade drive part 7 gradually opens the expander blades 5.

[0064] The excavation of the vertical hole 17 and the expansion of the diameter of the bottom 19 of the vertical hole 17 may be performed without using the drilling bit installation body 13. In other words, the first drilling bit 25 may be fixed directly to the arm-shaped member 9 of the expansion wing 5, and the excavation of the vertical hole 17 and the expansion of the diameter of the bottom 19 of the vertical hole 17 may be performed.

[0065] 3, 7(a)(b), etc., the expanded-bottom earth drill bucket 1 is provided with an expanded-bottom earth drill bucket adapter 45. The expanded-bottom earth drill bucket adapter (adapter) 45 is provided between the stabilizer 3 and the expanded-bottom earth drill bucket rotation support part 35, and connects the stabilizer 3 and the expanded-bottom earth drill bucket rotation support part 35.

[0066] The adapter 45 minimizes rattle between the stabilizer 3 and the bottom-expanding earth drill bucket rotation support part 35 in the direction of rotation of the stabilizer 3 by the bottom-expanding earth drill bucket rotation support part 35.

[0067] The adapter 45 will be further described. The adapter 45 is used to connect the rotary propelling body (kelly bar) 47 of the earth drill 43 and the stabilizer 3 of the bottom-expanding earth drill bucket 1, as shown in FIG.

[0068] 7 and other figures, the adapter 45 is configured to include an adapter main body 49 and a cylindrical first fitting portion 51. The first fitting portion 51 is provided integrally with the adapter main body 49 on the upper side thereof, for example, by welding. The first fitting portion 51 is fitted into a fitted portion 53 of the rotation propelling body 47, and transmits the rotational force (rotational torque) generated by the rotation propelling body 47 to the adapter main body 49.

[0069] For example, the first fitting portion 51 is formed in a rectangular cylindrical shape, with the internal space of the cylinder being square when viewed in the direction of extension of the central axis of the cylinder. The inner diameter of the first fitting portion 51 is, for example, about 160 mm. That is, the length and width of the internal space of the cylinder of the first fitting portion 51 when viewed in the direction of extension of the central axis of the cylinder are each about 160 mm.

[0070] The fitted portion 53 of the rotation propulsion body 47 is a quadrangular prism with a square bottom surface. The outer diameter of the fitted portion 53 of the rotation propulsion body 47 is also approximately 160 mm. However, the outer diameter of the fitted portion 53 is slightly smaller than the inner diameter of the first fitted portion 51. As a result, the first fitted portion 51 and the fitted portion 53 are engaged with each other in a loose fit state with a small gap between them.

[0071] In addition, the first fitting portion 51 and the fitted portion 53 may be formed in the shape of a quadrangular prism with a square bottom surface, and the fitted portion 53 may be formed in the shape of a rectangular cylinder.

[0072] The fixing pin 55 prevents the adapter 45 from coming off the rotation propulsion body 47 when the fitted portion 53 of the rotation propulsion body 47 is fitted into the first fitting portion 51 of the adapter 45.

[0073] Furthermore, the adapter 45 of the bottom-expanding earth drill bucket 1 is provided with a second fitting portion 57. The second fitting portion 57 is provided integrally with the adapter main body 49 on the lower side of the adapter main body 49, for example, by welding. Furthermore, the second fitting portion 57 is fitted into the fitted portion 59 of the stabilizer 3, so that the adapter main body 49 transmits the rotational force (rotational torque) transmitted from the rotation propulsion body 47 to the stabilizer 3.

[0074] Like the fitted portion 53, the second fitting portion 57 has a rectangular prism shape with a square bottom surface. The fitted portion 53 of the rotation propulsion body 47 has an outer diameter of approximately 140 mm. Like the first fitted portion 51, the fitted portion 59 has a rectangular cylindrical shape. The inner diameter of the fitted portion 59 is also approximately 140 mm. However, the inner diameter of the fitted portion 59 is slightly larger than the outer diameter of the second fitted portion 57. As a result, the second fitting portion 57 and the fitted portion 59 engage with each other in a loose fit state with a small gap. In addition, fixing pins 55 are installed in the second fitting portion 57 and the fitted portion 59.

[0075] In addition, with regard to the second fitting portion 57 and the fitted portion 59, the second fitting portion 57 may be formed in a rectangular cylindrical shape, and the fitted portion 59 may be formed in a quadrangular prism shape with a square bottom surface.

[0076] Here, the bottom-expanded earth drill bucket 1 and the like will be described in more detail.

[0077] As shown in Figure 3, the ground 15 consists of a soft layer 63 made of gravel, boulders, clay, etc., and a soft layer 63 made of ordinary earth and sand that covers the soft layer 63. For example, the vertical hole 17 penetrates the soft layer 63, and the entire bottom 19 of the vertical hole 17 is located in the hard layer 65. Therefore, the diameter expansion using the bottom expansion earth drill bucket 1 is performed at the hard layer 65.

[0078] The earth drill 43 is placed on the ground 15 and holds the upper end of, for example, a cylindrical steel pipe (drilling casing) 39, and moves downward while rotating the drilling casing 39 it holds.

[0079] The expansion wing 5 on which the first drilling bit 25 and the second drilling bit 41 are installed is kept closed, and the bottom-expanding earth drill bucket 1 is fixed to the drilling casing 39 by the bottom-expanding earth drill bucket fixing part 33 and the bottom-expanding earth drill bucket rotation support part 35. Then, the drilling casing 39 is rotated and moved downward to obtain the vertical hole 17.

[0080] As shown in FIG. 2 and other figures, the blade expansion drive unit 7 is configured to include an actuator such as a hydraulic cylinder 67, a central member 69, an engaging member 71, and a pair of connecting members 73 (73A, 73B). The central member 69 is formed in a generally cylindrical or other columnar shape, and extends downward from the lower center of the stabilizer 3. The central axis of the central member 69 coincides with the first central axis C1. The central member 69 is provided integrally with the stabilizer 3. A second drilling bit 41 is provided integrally with the lower end of the central member 69.

[0081] The engaging member 71 is formed in an annular shape and is attached to the central member 69 so that the central member 69 passes through the inside of the annulus. The engaging member 71 engages with the central member 69 so as to be movable in the up-down direction relative to the central member 69 (the longitudinal direction of the central member 69; the extension direction of the central axis C1).

[0082] A first connecting member 73A, which is one of the pair of connecting members 73, is formed in a rod shape. A second connecting member 73B, which is the other of the pair of connecting members 73, is also formed in a rod shape similar to the first connecting member 73A.

[0083] One longitudinal end of the first connecting member 73A is engaged with the engaging member 71. This engagement allows the first connecting member 73A to rotate relative to the engaging member 71 around a central axis C5 extending horizontally.

[0084] The other longitudinal end of the first connecting member 73A engages with the first arm member 9A at the longitudinal middle of the first arm member 9A. This engagement allows the first connecting member 73A to rotate relative to the first arm member 9A around a central axis C6 extending horizontally.

[0085] One longitudinal end of the second connecting member 73B is engaged with the engaging member 71. This engagement allows the second connecting member 73B to rotate relative to the engaging member 71 around a central axis C7 extending horizontally.

[0086] The other longitudinal end of the second connecting member 73B engages with the second arm member 9B at the longitudinal middle of the second arm member 9B. This engagement allows the second connecting member 73B to rotate relative to the second arm member 9B around a central axis C8 extending horizontally.

[0087] The hydraulic cylinder 67 is configured to include a cylindrical cylinder body 75, a piston 77 (see FIG. 7), and a piston rod 79. By allowing hydraulic oil to flow into the hydraulic cylinder 67 and allowing hydraulic oil to flow out of the hydraulic cylinder 67, the length of time that the piston rod 79 projects from the cylinder body 75 can be changed.

[0088] An end of the cylinder body 75 engages with the first arm member 9A at a longitudinal intermediate portion of the first arm member 9A. This engagement allows the cylinder body 75 to rotate relative to the first arm member 9A around a central axis C9 extending horizontally.

[0089] The end of the piston rod 79 engages with the second arm member 9B at a longitudinal intermediate portion of the second arm member 9B. This engagement allows the piston rod 79 to rotate relative to the second arm member 9B around a central axis C10 extending horizontally.

[0090] With this configuration, a limited chain mechanism is formed by the stabilizer 3, the central member 69, the engaging member 71, the connecting member 73, and the hydraulic cylinder 67. When the amount of protrusion of the piston rod 79 from the cylinder body 75 is at a minimum, the expansion wing 5 is in a closed state, and when the amount of protrusion of the piston rod 79 from the cylinder body 75 is at a maximum, the expansion wing 5 is in a maximum open state.

[0091] 1 to 3 and 6(a), the drilling bit placing bodies 13 are lined up in the longitudinal direction of the arm-shaped member 9, and are placed only on the lower portion of the expansion wing 5 (arm-shaped member 9). In contrast to this, as shown in FIG. 6(b), the drilling bit placing bodies 13 may be lined up in the longitudinal direction of the arm-shaped member 9, and be placed over the entire length of the expansion wing 5 (arm-shaped member 9). Note that what is indicated by reference numeral 26 in FIG. 2 etc. is a drilling bit that is provided directly and integrally with the arm-shaped member 9.

[0092] The bottom-expanding earth drill bucket fixing portion 33 is configured to include a main body portion 81, a pair of pad portions 83, and an extension portion 85. The extension portion 85 extends downward from the main body portion 81. The pad portions 83 are supported by the main body portion 81, and the main body portion 81 causes each of the pair of pad portions 83 to contact the inner surface of the drilling casing 39 with a pressing force. When each of the pair of pad portions 83 is in contact with the inner surface of the drilling casing 39 with a pressing force, the drilling casing 39, the pad portions 83, the main body portion 81, and the extension portion 85 are integrated.

[0093] The bottom-expanded earth drill bucket rotation support part 35 is configured to include a main body part 87 and an extension part 89. The lower end part of the extension part 85 of the bottom-expanded earth drill bucket fixing part 33 is joined to the main body part 87. The extension part 89 extends downward from the main body part 87. The lower end part of the extension part 89 is joined to the adapter 45.

[0094] The main body portion 87 is capable of switching between a state in which the extension portion 89 is driven to rotate relative to the main body portion 87 and a state in which the extension portion 89 is integrated with the main body portion 87 without rotating relative to the main body portion 87.

[0095] When each of the pair of pad portions 83 is in contact with the inner surface of the excavation casing 39 with a pressing force and the extension portion 89 is integrated with the main body portion 87, the stabilizer 3 and the excavation casing 39 are integrated. On the other hand, a state in which each of the pair of pad portions 83 is in contact with the inner surface of the excavation casing 39 with a pressing force and the extension portion 89 is rotationally driven relative to the main body portion 87 is called a rotationally driven state. In this rotationally driven state, the stabilizer 3 etc. rotate relative to the excavation casing 39 with the first central axis C1 as the rotation center.

[0096] 7, the adapter 45 is provided with a plurality of (for example, two) reinforcing members (reinforcing portions; rattle reduction portions) 91 in addition to the adapter main body 49, the first fitting portion 51, and the second fitting portion 57. The reinforcing members 91 are formed in an "L" shape. One end of the reinforcing member 91 is integrally joined to a predetermined portion on the outer periphery of the cylindrical portion 51 or to the adapter main body 49 by, for example, welding. The other end of the reinforcing member 91 is integrally joined to the stabilizer 3 using a fastening member such as a bolt 93.

[0097] This reduces rattles between the rotation propellant 47 and the stabilizer 3 in the rotational direction of the rotation propellant 47 and the stabilizer 3 compared to when the reinforcing member 91 is not provided. In other words, if the reinforcing member 91 is not provided, rattles would occur between the first fitting portion 51 and the fitted portion 53, and between the second fitting portion 57 and the fitted portion 59. In contrast, the provision of the reinforcing member 91 eliminates rattles between the second fitting portion 57 and the fitted portion 59. Furthermore, the provision of the reinforcing member 91 can improve the bonding strength between the rotation propellant 47 and the expanded-bottom earth drill bucket 1 (stabilizer 3).

[0098] 7(a), the reinforcing members 91 are provided in pairs, with one reinforcing member 91 being disposed on the left side of the first fitting portion 51 and the other reinforcing member 91 being disposed on the right side of the first fitting portion 51. The reinforcing members 91 are provided with ribs 113 for increasing the rigidity of the reinforcing members 91.

[0099] The annular member 29 of the drilling bit installing body 13 is formed in a circular ring shape with a rectangular cross section (a cross section taken along a plane perpendicular to the extension direction of the ring). The spiral member 31 of the drilling bit installing body 13 has a rectangular cross section (a cross section taken along a plane perpendicular to the extension direction of the spiral).

[0100] In the drilling bit installing body 13, a spiral gap 95 is formed between the plurality of spiral members 31. The volume of the gap 95 is larger than the volume of the spiral member 31.

[0101] Next, the operation of the bottom-expanding earth drill bucket 1 and the like in forming the vertical hole 17 and expanding the diameter of the bottom 19 of the vertical hole 17 will be described.

[0102] In the initial state, the drilling bit installation body 13 with the first drilling bit 25 installed on the expansion wing 5 is installed, a second drilling bit 41 is installed in the bottom-expanded earth drill bucket 1, and an earth drill 43 is placed on the ground 15. In the initial state, the bottom-expanded earth drill bucket 1 is installed integrally with the drilling casing 39 by the bottom-expanded earth drill bucket fixing part 33 and the bottom-expanded earth drill bucket rotation support part 35. In the initial state, the stabilizer 3 of the bottom-expanded earth drill bucket 1 is integrated with the drilling casing 39. Also, in the initial state, the expansion wing 5 is in a closed state, the drilling casing 39 and the bottom-expanded earth drill bucket 1 are located on the ground 15, and the drilling casing 39 is installed on the earth drill 43.

[0103] In the above initial state, the drilling casing 39 is rotated and moved downward by the earth drill 43. Then, when the drilling casing 39 has been moved a predetermined distance, a cylindrical vertical hole 17 is obtained whose bottom 19 has not been enlarged in diameter.

[0104] After this, the diameter of the bottom 19 of the vertical hole 17 is expanded. In this expansion, the bottom-expanding earth drill bucket fixing part 33 is fixed to the drilling casing 39, and the expansion blades 5 are rotated by the bottom-expanding earth drill bucket rotation support part 35 while the expansion blades 5 are gradually opened by the expansion blade drive part 7. The expansion of the bottom 19 of the vertical hole 17 is completed by opening the expansion blades 5 to their maximum opening state.

[0105] Here, the principle of expanding the diameter of the bottom 19 of the vertical hole 17 using the bottom-expanding earth drill bucket 1 will be described in more detail with reference to FIG. 5, which shows a schematic diagram of the diameter expansion.

[0106] Member 97 and member 99 are connected by a hydraulic cylinder 67. A drilling bit installation body 13 is provided at the tip of member 97 so as to rotate around a second central axis C2 (see arrow A2). Member 99 is configured to rotate around a first central axis C1 (see arrow A1).

[0107] Hydraulic oil is supplied to the first internal space 101 of the hydraulic cylinder 67 from a hydraulic source 105. The pressure of the hydraulic oil supplied to the first internal space 101 is maintained at a constant value by a pressure regulating valve 107 and a relief valve 109 even when the piston 77 and the piston rod 79 (the drilling bit installation body 13) move and the volume of the first internal space 101 changes. The second internal space 103 of the hydraulic cylinder 67 serves as a drain.

[0108] When members 97 and 99 are rotated in the direction of arrow A1, the drilling bit installation body 13 and the first drilling bit 25 rotate in the direction of arrow A2, the portion 111 of the ground 15 to be cut is cut, and the diameter of the bottom 19 of the vertical hole 17 is expanded.

[0109] In the above description, the formation of the vertical hole 17 before enlarging the diameter of the bottom 19 and the enlarging of the bottom 19 are performed using the bottom-expanding earth drill bucket 1. Alternatively, the formation of the vertical hole 17 before enlarging the diameter of the bottom 19 may be performed using a drill or other excavation tool, and then the bottom 19 of the vertical hole 17 may be enlarged using the bottom-expanding earth drill bucket 1.

[0110] In the bottom-expanding earth drill bucket 1, a drilling bit (first drilling bit) 25 is installed on the expansion wing 5 of the bottom-expanding earth drill bucket 1 using a drilling bit installation body 13. The drilling bit installation body 13 includes a drilling bit installation body main body 21 supported on the expansion wing 5 so as to rotate around the second central axis C2, and a plurality of drilling bit installation parts 23 provided on the drilling bit installation body main body 21 and on which the first drilling bit 25 is installed.

[0111] When expanding the diameter of the bottom 19 of the vertical hole 17 excavated in the ground 15, the excavation bit (first excavation bit) 25 rotates about the second central axis C2 and also revolves about the first central axis C1. Therefore, the degree of freedom of movement of the excavation bit 25 relative to the ground 15 is higher than that of the bottom-expanding bucket 307 of the conventional central excavator 301.

[0112] As a result, even if the bottom 19 of the vertical hole 17 is formed of the hard layer 65, the drilling bit 25 is less likely to get caught on the hard layer 65, and it is possible to minimize the occurrence of a situation in which the rotation of the expansion wing 5 about the first central axis C1 stops. Furthermore, even if the bottom 19 of the vertical hole 17 is formed of the hard layer 65, it is possible to enable the diameter to be expanded in the hard layer 65, and it is also possible to shorten the time required for the diameter to be expanded in the hard layer 65.

[0113] In addition, in the expanded bottom earth drill bucket 1, the multiple drilling bit setting sections 23 are arranged along multiple first spirals extending around the outer periphery of the drilling bit setting body main body 21, and the multiple first spirals are arranged in the circumferential direction of the drilling bit setting body main body 21.

[0114] As a result, for one drilling bit installation body 13, for example, the multiple drilling bits 25 are configured to continuously excavate the hard layer 65 of the ground 15 with a time lag. That is, when the hard layer 65 is being excavated, at least one drilling bit 25 of the multiple drilling bits 25 is excavating the hard layer 65. Even if the bottom 19 of the vertical hole 17 is formed of the hard layer 65, the drilling bit installation body 13 can rotate smoothly around the second central axis C2, further shortening the time required for diameter expansion.

[0115] In the expanded-bottom earth drill bucket 1, the drilling bit placing body main body 21 is configured with an annular member 29 and multiple helical members 31. Each of the multiple helical members 31 has a first end joined to a first annular member 29A and a second end joined to a second annular member 29B. Each of the helical members 31 is positioned so as to evenly distribute the circumference of the annular member 29. Each of the multiple helical members 31 is provided with multiple drilling bit placing sections 23. The interior of the drilling bit placing body 13 is hollowed out. This facilitates the discharge of finely divided soil and sand generated during drilling with the drilling bit 25.

[0116] In addition, when drilling the vertical hole 17, the widening wing 5 on which the first drilling bit 25 is installed is closed and the widening wing earth drill bucket fixing part 33 is fixed to the drilling casing 39. Furthermore, when drilling the vertical hole 17, the widening wing 5 is prevented from rotating relative to the drilling casing 39 by the widening earth drill bucket rotation support part 35, and the drilling casing 39 is rotated by the earth drill 43 and moves downward.

[0117] In addition, with the bottom-expanding earth drill bucket 1, after the drilling of the vertical hole 17 is completed, the bottom-expanding earth drill bucket fixing part 33 is fixed to the drilling casing, and the bottom-expanding earth drill bucket rotation support part 35 rotates the widening blades 5 relative to the drilling casing 39. At this time, the widening blade drive part 7 gradually opens the widening blades 5.

[0118] This allows the bottom-expanding earth drill bucket 1 to excavate the vertical hole 17 and expand the diameter of the bottom 19 of the excavated vertical hole 17.

[0119] The adapter 45 is configured to include an adapter main body 49 and a first fitting portion 51. The first fitting portion 51 is provided integrally with the adapter main body 49 on the upper side of the adapter main body 49, and is fitted into a fitted portion 53 of the rotation propulsion body 47 so as to transmit the rotational force generated by the rotation propulsion body 47 to the adapter main body 49 with reduced rattle.

[0120] Here, multiple types of adapters 45 are prepared with different dimensions of the first fitting portion 51 and the second fitting portion 57. If the dimensions of the fitted portion 53 of the rotary propellant 47 of the earth drill 43 or the dimensions of the fitted portion 59 of the stabilizer 3 change, an adapter 45 appropriately selected from the multiple types of adapters 45 may be used to join the bottom-expanded earth drill bucket 1 to the rotary propellant 47 of the earth drill 43 with almost no rattle.

[0121] Furthermore, it is possible to minimize misalignment of the expanded-bottom earth drill bucket 1 relative to the central axis of rotation of the rotary propellant 47 of the earth drill 43, thereby making it possible to produce a vertical hole 17 of accurate shape and expand the diameter of the bottom 19 of this vertical hole 17 to an accurate shape.

[0122] Here, the above description may be understood as a method for constructing a bottom-expanded hole.

[0123] In other words, this may be understood as a method for constructing a bottom-expanding hole using a bottom-expanding earth drill bucket 1 having a drilling bit 41 attached to the lower end of the expansion wing 5, in which the expansion wing on which the first drill bit is attached is closed, the bottom-expanding earth drill bucket fixing part is fixed to the drilling casing, the bottom-expanding earth drill bucket rotation support part is used to prevent the expansion wing from rotating relative to the drilling casing, and the drilling casing is rotated and moved downward to excavate the ground to form a vertical hole (a vertical hole excavation process), and after the excavation of the vertical hole in the vertical hole excavation process is completed, the bottom-expanding earth drill bucket fixing part is fixed to the drilling casing, the bottom-expanding earth drill bucket rotation support part is used to rotate the expansion wing relative to the drilling casing, and the expansion wing is gradually opened by the expansion wing drive part, thereby expanding the diameter of the bottom of the vertical hole.

[0124] Although the present embodiment has been described above, the present embodiment is not limited to this, and various modifications are possible within the scope of the gist of the present embodiment. [Explanation of symbols]

[0125] 1. Wide-bottom earth drill bucket 3. Stabilizer 5 Widened wings 7. Widening wing drive unit 9, 9A, 9B Arm-shaped members 11 Drilling bit installation body installation section 13 Drilling bit installation body 15 Ground 17 Vertical hole 19 Bottom 21 Drilling bit installation body main body 23 Drilling bit installation section 25 First Drilling Bit 29, 29A, 29B Annular members 31 Spiral member 33 Enlarged bottom earth drill bucket fixing part 35 Rotating support part for widened bottom earth drill bucket 39 Drilling casing 41 Second Drilling Bit 45 adapter 47 Rotating Propellant (Kellyba) 49 Adapter body 51 first fitting portion 53 Fitted part (fitted part of rotation propulsion body) 57 Second fitting part 59 Engaged part (engaged part of stabilizer) 91 Reinforcement member C1 First central axis C2 Second central axis

Claims

1. A stabilizer and a first arm-shaped member that is one of the pair of arm-shaped members and that is rotatably engaged with the stabilizer at its upper end in the longitudinal direction, and a second arm-shaped member that is the other of the pair of arm-shaped members and that is rotatably engaged with the stabilizer at its upper end in the longitudinal direction, a first drilling bit is installed on the outer periphery, a second drilling bit is installed on the bottom, and a widening wing that rotates around a first central axis as a rotation center; a wing expansion drive unit that rotates the arm-shaped members relative to the stabilizer; a bottom-expanded earth drill bucket fixing portion that is fixed to a drilling casing that forms a wall portion of a vertical hole dug in the ground; a bottom-expanding earth drill bucket rotation support part that is supported by the bottom-expanding earth drill bucket fixing part and that drives the widening blade to rotate relative to the drilling casing when the bottom-expanding earth drill bucket fixing part is fixed to the drilling casing, or that prevents the widening blade from rotating relative to the drilling casing when the bottom-expanding earth drill bucket fixing part is fixed to the drilling casing; An earth drill bucket having an expanded bottom.

2. An adapter for an expanded bottom earth drill bucket that connects a rotary propulsion body and a stabilizer of the expanded bottom earth drill bucket, an adapter main body; a first fitting portion that is integrally provided on an upper side of the adapter main body with the adapter main body, that fits into the fitted portion of the rotational propulsion body, and that transmits a rotational force generated by the rotational propulsion body to the adapter main body; a second fitting portion that is provided integrally with the adapter main body below the adapter main body, that is fitted into the fitted portion of the stabilizer, and that transmits a rotational force generated by the rotation propulsion body to the stabilizer; a reinforcing member having one end integrally joined to the adapter body and the other end integrally joined to the stabilizer; Adapter for earth drill bucket with enlarged bottom.

3. 2. A method for constructing a bottom-expanded hole using the bottom-expanded earth drill bucket according to claim 1, wherein a second drilling bit is provided at the lower end of the widening wing, a vertical hole excavation step in which the widening wing on which the first drill bit is installed is closed, the widening earth drill bucket fixing part is fixed to the drilling casing, and the widening earth drill bucket rotation support part prevents the widening wing from rotating relative to the drilling casing, and the drilling casing is rotated and moved downward to excavate the ground and form a vertical hole; a vertical hole bottom diameter expanding step in which, after the drilling of the vertical hole is completed in the vertical hole drilling step, the bottom-expanding earth drill bucket fixing part is fixed to the drilling casing, and the bottom-expanding earth drill bucket rotation support part rotates the widening blade relative to the drilling casing while the widening blade drive part gradually opens the widening blade, thereby expanding the diameter of the bottom of the vertical hole; A method for constructing an enlarged bottom hole, comprising:

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