Excavation bit installation body and under-reamed earth drill bucket

Abstract

To provide a construction method of a bottom enlarge hole allowing a vertical hole drilled in the ground to be enlarged and time necessary to enlarge the hole to be reduced when enlarging a diameter of the bottom of the vertical hole, even if the bottom of the vertical hole is formed of a hard layer.SOLUTION: An installation body 13 for a drill bit installed on a width enlarge blade 5 rotating around a first central axis C1 to enlarge a diameter of a bottom 19 of a vertical hole 17 drilled in a ground 15 as a rotational center comprises: an installation body part 21 for a drill bit supported with the width enlarge blade 5 so as to rotate around a second central axis C2 as a rotational center; and a plurality of installation body parts for a drill bit 23 disposed on the installation body part 21 for a drill bit, on which a first drill bit 25 is installed.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a bit installation body for excavation. and an earth auger bucket with an enlarged bottom

Background Art

[0002] Conventionally, an inner excavation machine 301 as shown in FIG. 8 has been known (see Patent Document 1). The inner excavation machine 301 is adapted to be mounted inside an excavation casing 303 used in the all-casing method.

[0003] The inner excavation machine 301 includes a drive device 305 detachably fixed inside the excavation casing 303, and an underreaming bucket 307 interlocked and connected to the drive device 305. The drive device 305 includes 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 rotatably and vertically disposed at the center of the casing body 309, and the underreaming bucket 307 is connected to the lower end of the drive shaft 311. The rotary drive unit 313 is adapted to rotationally drive the drive shaft 311. The feeder device 315 is adapted to vertically move the drive shaft 311. The chuck device 317 is adapted to press 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 underreaming bucket 307 is adapted to expand the diameter of the bottom of a vertical hole (for example, a cylindrical vertical hole) not surrounded by the excavation casing 303 into a frustum of a cone. An excavation bit 321 is integrally provided on the expanding wing 319. Then, by rotating and expanding the expanding wing 319, the ground is cut by the excavation bit 321, and the bottom of the vertical hole is expanded into a frustum of a cone.

Prior Art Documents

Patent Documents

[0006] ​ [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-114543 [Summary of the Invention] [Problems to be Solved by the Invention]

[0007] By the way, when the ground is soft general earth and sand, it is possible to easily expand the diameter of the bottom of the vertical hole using the conventional middle excavation machine 301. However, there is a hard layer (such as rock, boulders, or clay) below the soft general earth and sand, and in many cases, the diameter of the bottom of the vertical hole is expanded in the hard layer.

[0008] When attempting to expand the diameter of the bottom of the vertical hole using the conventional middle excavation machine 301 in the hard layer of the ground, since the excavation bit 321 is fixed to the expanding wing 319, it may take a long time to expand the diameter, or a situation may occur where the diameter cannot be expanded.

[0009] An object of the present invention is to provide a device that can expand the diameter of the bottom of a vertical hole dug in the ground even when the bottom of the vertical hole is formed in a hard layer, and can also shorten the time required for diameter expansion. [Means for Solving the Problems]

[0010] The excavation bit installation body according to an aspect of the present invention is an excavation bit installation body installed on an expanding wing that rotates about a first central axis to expand the diameter of the bottom of a vertical hole dug in the ground, and includes an excavation bit installation body main body portion supported by the expanding wing so as to rotate about a second central axis, and a plurality of excavation bit installation portions provided on the excavation bit installation body main body portion and having first excavation bits installed thereon.

[0011] In addition, in the bit installation body for excavation according to an aspect of the present invention, the plurality of bit installation portions for excavation are arranged along a helix extending on the outer peripheral portion of the main body portion of the bit installation body for excavation, there are a plurality of the helices, and the plurality of helices are arranged in the circumferential direction of the main body portion of the bit installation body for excavation.

[0012] In addition, in the bit installation body for excavation according to an aspect of the present invention, the main body portion of the bit installation body for excavation is configured to include a pair of annular members and a plurality of spiral members, the pair of annular members have their central axes coinciding with each other and are separated from each other by a predetermined distance in the extending direction along their central axes, each of the plurality of spiral members has one end in the longitudinal direction joined to one of the pair of annular members, the other end in the longitudinal direction joined to the other of the pair of annular members, the plurality of spiral members are arranged at positions equally distributing around the annular members, the plurality of bit installation portions for excavation are provided on each of the plurality of spiral members and are arranged at predetermined intervals in the extending direction of the spiral members.

[0013] The under-reaming earth drill bucket according to an aspect of the present invention is composed of a stabilizer and a pair of arm-like members. A first arm-like member, which is one of the pair of arm-like members, is rotatably engaged with the stabilizer at the upper end portion in its longitudinal direction, a second arm-like member, which is the other of the pair of arm-like members, is rotatably engaged with the stabilizer at the upper end portion in its longitudinal direction, the under-reaming wing provided with a bit installation body installation portion where the bit installation body for excavation is installed, and an under-reaming wing drive portion for rotating the pair of arm-like members with respect to the stabilizer.

[0014] In addition, the under-reaming earth drill bucket according to an aspect of the present invention includes an under-reaming earth drill bucket fixing portion fixed to a drilling casing forming a wall portion of the vertical hole, and is supported by the under-reaming earth drill bucket fixing portion. In a state where the under-reaming earth drill bucket fixing portion is fixed to the drilling casing, the under-reaming earth drill bucket fixing portion rotationally drives the under-reaming wings with respect to the drilling casing, or in a state where the under-reaming earth drill bucket fixing portion is fixed to the drilling casing, prevents the under-reaming wings from rotating with respect to the drilling casing, and has an under-reaming earth drill bucket rotation support portion.

[0015] In addition, the under-reaming earth drill bucket according to an aspect of the present invention includes a second drilling bit provided at a lower end of the under-reaming wings. When drilling the vertical hole, the under-reaming wings on which the first drilling bit is installed are closed, the under-reaming earth drill bucket fixing portion is fixed to the drilling casing, and the under-reaming earth drill bucket rotation support portion prevents the under-reaming wings from rotating with respect to the drilling casing. The drilling casing is rotated and moved downward. After finishing drilling the vertical hole, the under-reaming earth drill bucket fixing portion is fixed to the drilling casing, and while rotating the under-reaming wings with respect to the drilling casing by the under-reaming earth drill bucket rotation support portion, the under-reaming wings are gradually opened by the under-reaming wing driving portion.

[0016] The under-reaming earth drill bucket according to an aspect of the present invention includes a stabilizer and a plurality of arm-like members. Among the pair of arm-like members, a first arm-like member, which is one of the arm-like members, is rotatably engaged with the stabilizer at the upper end portion in the longitudinal direction thereof. A second arm-like member, which is the other of the pair of arm-like members, is rotatably engaged with the stabilizer at the upper end portion in the longitudinal direction thereof. A first excavation bit is installed on the outer peripheral portion, a second excavation bit is installed at the bottom, a widening wing that rotates about a first central axis as a rotation center, a widening wing driving portion that rotates the plurality of arm-like members with respect to the stabilizer, an under-reaming earth drill bucket fixing portion that is fixed to an excavation casing that forms a wall portion of a vertical hole dug in the ground, and an under-reaming earth drill bucket rotation support portion that is supported by the under-reaming earth drill bucket fixing portion and rotates the widening wing with respect to the excavation casing in a state where the under-reaming earth drill bucket fixing portion is fixed to the excavation casing, or prevents the widening wing from rotating with respect to the excavation casing in a state where the under-reaming earth drill bucket fixing portion is fixed to the excavation casing.

[0017] An adapter of the under-reaming earth drill bucket according to an aspect of the present invention is an adapter of the under-reaming earth drill bucket that connects a rotary propulsion body and a stabilizer of the under-reaming earth drill bucket, and includes an adapter main body portion, a first fitting portion that is integrally provided on the upper side of the adapter main body portion and is fitted into a fitted portion of the rotary propulsion body to transmit the rotational force generated by the rotary propulsion body to the adapter main body portion, a second fitting portion that is integrally provided on the lower side of the adapter main body portion and is fitted into a fitted portion of the stabilizer to transmit the rotational force generated by the rotary propulsion body to the stabilizer, and a reinforcing member having one end integrally joined to the adapter main body portion and the other end integrally joined to the stabilizer.

[0018] The method for constructing an under-reamed hole according to an aspect of the present invention is a method for constructing an under-reamed hole using an under-reaming earth drill bucket in which a second drilling bit is provided at the lower end of the under-reaming wing. The method includes closing the under-reaming wing on which the first drilling bit is installed, fixing the under-reaming earth drill bucket fixing portion to the casing for drilling, and preventing the rotation of the under-reaming wing with respect to the casing for drilling by the under-reaming earth drill bucket rotation support portion. By rotating and moving the casing for drilling downward, a vertical hole is drilled in the ground to provide a vertical hole drilling step. After the vertical hole is drilled in the vertical hole drilling step, the under-reaming earth drill bucket fixing portion is fixed to the casing for drilling, and while rotating the under-reaming wing with respect to the casing for drilling by the under-reaming earth drill bucket rotation support portion, the under-reaming wing is gradually opened by the under-reaming wing driving portion to expand the diameter of the bottom of the vertical hole, which is an under-reaming step for expanding the bottom diameter of the vertical hole.

Effect of the Invention

[0019] According to the present invention, when expanding the diameter of the bottom of a vertical hole dug in the ground, even if the bottom of the vertical hole is formed of a hard layer, the diameter can be expanded, and the time required for diameter expansion can be shortened.

Brief Description of the Drawings

[0020]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Mode for Carrying Out the Invention

[0021] The under-reaming earth drill bucket (under-reaming bucket) 1 according to the embodiment of the present invention is configured to include a stabilizer 3, a widening wing 5, and a widening wing driving unit 7 as shown in FIGS. 1 to 3.

[0022] The outer shape of the stabilizer 3 is roughly formed in a low columnar shape. The stabilizer 3 and the widening wing 5 are configured to rotate about the first central axis C1. Note that the central axis of the stabilizer 3 coincides with the first central axis C1. Although the first central axis C1 extends in the vertical direction, it may extend in a direction inclined obliquely with respect to the vertical direction or in the horizontal direction.

[0023] The widening wing 5 is configured to include a plurality of (for example, a pair of) arm-like members 9 (9A, 9B). The first arm-like member 9A, which is one of the pair of arm-like members 9, is formed in a substantially linear rod shape. The first arm-like member 9A is rotatably engaged with the stabilizer 3 at the upper end portion in the longitudinal direction thereof.

[0024] The second arm-shaped member 9B, which is the other arm-shaped member of the pair of arm-shaped members 9, is formed in the same manner as the first arm-shaped member 9A. The second arm-shaped member 9B is also rotatably engaged with the stabilizer 3 at the upper end portion in the longitudinal direction thereof.

[0025] Further, the widening wings 5 (arm-shaped members 9A, 9B) are provided with a boring bit installation body installation portion 11 on which a boring bit installation body 13 (see FIG. 4 etc.) is installed. Details of the boring bit installation body 13 will be described later.

[0026] The first arm-shaped member 9A is engaged with the stabilizer 3 in the vicinity of the outer periphery of the stabilizer 3, and the second arm-shaped member 9B is engaged with the stabilizer 3 at a location in the vicinity of 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] As shown in FIG. 2, the rotation center axis C3 of the first arm-shaped member 9A with respect to the stabilizer 3 and the rotation center axis C4 of the second arm-shaped member 9B with respect to the stabilizer 3 are parallel to each other and extend substantially in the horizontal direction. Further, the second arm-shaped member 9B is arranged symmetrically with the first arm-shaped member 9A with respect to the first central axis C1.

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

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

[0030] 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. This state is defined as the open state of the expansion wing 5. In the open state of the expansion wing 5, the distance (horizontal distance) between the first arm-shaped member 9A and the second arm-shaped member 9B gradually increases as it goes downward of the first arm-shaped member 9A and the second arm-shaped member 9B.

[0031] Also, the open state of the expansion wing 5 is a state other than the closed state of the expansion wing 5. In the open state of the expansion wing 5, as the opening angle of the expansion wing 5 increases, the intersection angle between the extending direction of the first arm-shaped member 9A and the first central axis C1 gradually increases. Further, the intersection angle between the extending direction of the second arm-shaped member 9B and the first central axis C1 also gradually increases.

[0032] The state in which the intersection angle between the extending direction of the first arm-shaped member 9A and the first central axis C1 reaches the maximum value and the intersection angle between the extending direction of the second arm-shaped member 9B and the first central axis C1 reaches the maximum value is defined as the maximum open state of the expansion wing 5 (see FIGS. 2, 3, and 6).

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

[0034] The boring bit installation body 13 will be described in detail with reference to FIGS. 3, 4, etc.

[0035] The bit installation body 13 for excavation is installed and used in the bit installation body installation part 11 (see FIGS. 1, 2, etc.) of the widening wing 5 (arm-shaped member 9). The widening wing 5 is configured to rotate about the first central axis C1 in order to expand the diameter of the bottom 19 of the 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 coincide with each other.

[0036] A plurality of bit installation body installation parts 11 for the widening wing 5 are provided. The plurality of bit installation body installation parts 11 are arranged on the outer side (the side opposite to the first central axis C1) of the arm-shaped member 9A (arm-shaped member 9B) at a predetermined interval in the extending direction (longitudinal direction) of the arm-shaped member 9A (arm-shaped member 9B). Further, the bit installation body 13 is detachably installed in each of the plurality of bit installation body installation parts 11.

[0037] The bit installation body 13 for excavation is provided with a bit installation body main body part 21 and a plurality of bit installation parts 23.

[0038] The bit installation body main body part 21 is supported by the widening wing 5 on the outer side (the side opposite to the first central axis C1) of the widening wing 5. More specifically, the bit installation body main body part 21 is installed on the arm-shaped member 9 via the bit installation body support 24. The bit installation body support 24 is integrally installed on the arm-shaped member 9 by a fastener such as a bolt.

[0039] The bit installation body main body part 21 supported by the widening wing 5 (arm-shaped member 9) is configured to rotate with respect to the widening wing 5 about the second central axis C2. The second central axis C2 extends, for example, in a direction parallel to the longitudinal direction of the widening wing 5 (arm-shaped member 9). More specifically, the bit installation body main body part 21 is configured to rotate about the second central axis C2 with respect to the bit installation body support 24 integrally provided on the arm-shaped member 9.

[0040] Note that the longitudinal direction of the widening wing 5 (the longitudinal direction of the arm-like member 9; the extending direction of the second central axis C2) coincides with the extending direction of the first central axis C1 when the excavation bit installation body 13 is installed on the widening wing 5 and the widening wing 5 is closed. When the widening wing 5 is opened while the excavation bit installation body 13 is installed on the widening wing 5, the intersection angle between the longitudinal direction of the widening wing 5 and the first central axis C1 gradually increases as the widening wing 5 opens.

[0041] The main body part 21 of the excavation bit installation body is roughly formed in a columnar or cylindrical shape, and the central axes of these columns, circles, etc. coincide with the second central axis C2.

[0042] Each of the plurality of excavation bit installation parts 23 is provided on the outer peripheral part of the main body part 21 of the excavation bit installation body. An excavation bit (first excavation bit) 25 is integrally installed on each of the plurality of excavation bit installation parts 23.

[0043] The diameter expansion of the bottom 19 of the vertical hole 17 dug in the ground 15 (see FIG. 3) is achieved by cutting the ground 15 with the first excavation bit 25 provided in the excavation bit installation part 23 of the main body part 21 of the excavation bit installation body.

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

[0045] As shown in Fig. 3, the shape of the bottom 19 of the vertically enlarged hole 17 is frustum-shaped with the diameter of the lower surface being larger than that of the upper surface. The central axis of the frustum of the bottom 19 of the vertically enlarged hole 17 coincides with the central axis of the cylindrical vertical hole 17, and the diameter of the upper surface of the frustum of the bottom 19 of the vertically enlarged hole 17 coincides with the diameter of the cylindrical vertical hole 17.

[0046] As shown in Fig. 4, each of the plurality of bit installation parts 23 for excavation is arranged at predetermined intervals along a helix (the first helix). The above-mentioned first helix extends on the outer peripheral part of the main body part 21 of the bit installation body for excavation. That is, the above-mentioned first helix extends so as to wind around the outer periphery of the main body part 21 of the bit installation body for excavation.

[0047] There are a plurality of (for example, four) above-mentioned first helices. The plurality of above-mentioned first helices are arranged at predetermined intervals in the circumferential direction of the main body part 21 of the bit installation body for excavation. The central axis of the above-mentioned first helix coincides with the second central axis C2.

[0048] In a state where each of the plurality of first bits 25 for excavation is installed in each of the plurality of bit installation parts 23 for excavation, each of the cutting edges 27 of the plurality of first bits 25 for excavation is arranged along each of the plurality of second helices.

[0049] The central axis of the second helix also coincides with the second central axis C2. Each of the plurality of above-mentioned second helices extends parallel to each of the plurality of above-mentioned first helices outside the plurality of above-mentioned first helices.

[0050] The number of turns of the above-mentioned first helix and the above-mentioned second helix is, for example, 1 or less and 0.1 or more. More specifically, the number of turns of the above-mentioned first helix and the above-mentioned second helix is about 1 / 4.

[0051] Further, the number of the first spirals is approximately equal to the reciprocal of the number of turns of the first spiral. For example, when the number of turns of the first spiral is "1 / 4", the number of the first spirals is four. As already understood, the number of turns of the first spiral and the number of turns of the second spiral match each other, and the number of the first spirals and the number of the second spirals match each other.

[0052] The main body portion 21 of the bit installation body for excavation is configured to include a pair of annular members (for example, annular members) 29 (29A, 29B) and a plurality of (for example, four) spiral members 31. The number of the spiral members 31 matches the number of the first spirals (second spirals), and the spiral members 31 extend along the first spiral and the second spiral.

[0053] The pair of annular members 29 (29A, 29B) have their central axes coinciding with each other and are separated from each other by a predetermined distance in the extending direction along these central axes. The central axes of the pair of annular members 29 (29A, 29B) coincide with the second central axis C2. Note that the value of the height dimension of the annular member 29B (the dimension in the extending direction of the second central axis C2) is larger than the value of the height dimension of the annular member 29A.

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

[0055] The plurality of bit installation portions 23 for excavation are provided on each of the plurality of spiral members 31 and are arranged at a predetermined interval in the extending direction of the spiral of the spiral member 31.

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

[0057] The bottom-expanded earth drill bucket fixing part 33 enters into a casing for excavation (for example, a cylindrical steel pipe) 39 that forms a wall part of the vertical hole 17 (the wall part that partitions the ground 15 and the space 37 of the vertical hole 17), and is fixed to the casing for excavation 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 casing for excavation 39, the bottom-expanded earth drill bucket rotation support part 35 is configured to rotationally drive the stabilizer 3 and the width-expanding wing 5 with respect to the casing for excavation 39, for example, by hydraulic pressure. Or, with the bottom-expanded earth drill bucket fixing part 33 fixed to the casing for excavation 39, the bottom-expanded earth drill bucket rotation support part 35 is configured to prevent the stabilizer 3 and the width-expanding wing 5 from rotating with respect to the casing for excavation 39.

[0059] A state in which the bottom-expanded earth drill bucket fixing part 33 is fixed to the casing for excavation 39 and, moreover, the stabilizer 3 and the width-expanding wing 5 are prevented from rotating with respect to the casing for excavation 39 is defined as a fixed state. In this fixed state, the width-expanding wing 5 and the stabilizer 3 are fixed to the casing for excavation 39 and integrated with the casing for excavation 39.

[0060] Further, the bottom-expanded earth drill bucket 1 is configured to include a second excavation bit 41 provided at the lower end of the width-expanding wing 5.

[0061] The vertical hole 17 is drilled as follows. The widening wings 5 are closed. Note that the first drilling bit 25 is installed on the widening wings 5 using the drilling bit installation body 13. When drilling the vertical hole 17, the underreamer bucket fixing part 33 is fixed to the drilling casing 39, and the rotation of the widening wings 5 with respect to the drilling casing 39 is blocked by the underreamer bucket rotation support part 35. Further, the drilling casing 39 installed on the earth drill 43 is rotated by the earth drill 43 and moved downward.

[0062] After finishing the drilling of the vertical hole 17, 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 finishing the drilling of the vertical hole 17, the diameter of the bottom 19 of the vertical hole 17 is enlarged as follows. The underreamer bucket fixing part 33 is fixed to the drilling casing 39. While rotating the widening wings 5 with respect to the drilling casing 39 by the underreamer bucket rotation support part 35, the widening wings 5 are gradually opened by the widening wing driving part 7.

[0064] Note that such drilling of the vertical hole 17 and enlargement of the diameter of the bottom 19 of the vertical hole 17 may also be performed without using the drilling bit installation body 13. That is, the first drilling bit 25 may be directly fixed to the arm-like member 9 of the widening wings 5, and the vertical hole 17 may be drilled and the diameter of the bottom 19 of the vertical hole 17 may be enlarged.

[0065] Also, as shown in FIG. 3, FIGS. 7(a) and (b), etc., the underreamer bucket 1 includes an adapter 45 of the underreamer bucket. The adapter (adapter) 45 of the underreamer bucket is provided between the stabilizer 3 and the underreamer bucket rotation support part 35, and connects the stabilizer 3 and the underreamer bucket rotation support part 35.

[0066] The adapter 45 is configured to minimize the play between the stabilizer 3 and the rotary support portion 35 of the under-reaming earth drill bucket in the rotational direction of the stabilizer 3 by the rotary support portion 35 of the under-reaming earth drill bucket.

[0067] The adapter 45 will be further described. As shown in FIG. 7 and the like, the adapter 45 is used for connecting the rotary drive body (kelly bar) 47 of the earth drill 43 and the stabilizer 3 of the under-reaming earth drill bucket 1.

[0068] As shown in FIG. 7 and the like, the adapter 45 includes an adapter main body portion 49 and a cylindrical first fitting portion 51. The first fitting portion 51 is integrally provided on the upper side of the adapter main body portion 49, for example, by welding. Further, the first fitting portion 51 is fitted into the fitted portion 53 of the rotary drive body 47 so as to transmit the rotational force (rotational torque) generated by the rotary drive body 47 to the adapter main body portion 49.

[0069] For example, the first fitting portion 51 is formed in a rectangular cylindrical shape in which the internal space of the cylinder as viewed in the extending direction of the central axis of the cylinder is square. The inner diameter of the first fitting portion 51 is about □160 mm, for example. That is, each of the vertical and horizontal dimensions of the internal space of the cylinder of the first fitting portion 51 as viewed in the extending direction of the central axis of the cylinder is about 160 mm.

[0070] The fitted portion 53 of the rotary drive body 47 is formed in a quadrangular prism shape with a square bottom surface. And the outer diameter of the fitted portion 53 of the rotary drive body 47 is also about □160 mm. However, the value of the outer diameter of the fitted portion 53 is slightly smaller than the value of the inner diameter of the first fitting portion 51. Thereby, the first fitting portion 51 and the fitted portion 53 are engaged with each other in a clearance fit state with a slight clearance.

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

[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 to the first fitting portion 51 of the adapter 45.

[0073] In addition, the adapter 45 of the under-reamed earth drill bucket 1 is provided with a second fitting portion 57. The second fitting portion 57 is integrally provided with the adapter main body portion 49, for example, by welding, below the adapter main body portion 49. Further, the second fitting portion 57 is fitted to the fitted portion 59 of the stabilizer 3 so that the adapter main body portion 49 transmits the rotational force (rotational torque) transmitted from the rotation propulsion body 47 to the stabilizer 3.

[0074] Similar to the fitted portion 53, the second fitting portion 57 has a quadrangular prism shape with a square bottom surface. The outer diameter of the fitted portion 53 of the rotation propulsion body 47 is about 140 mm. The fitted portion 59 is formed in a rectangular cylindrical shape, similar to the first fitting portion 51. The inner diameter of the fitted portion 59 is also about 140 mm. However, the value of the inner diameter of the fitted portion 59 is slightly larger than the value of the outer diameter of the second fitting portion 57. Thus, the second fitting portion 57 and the fitted portion 59 are engaged with each other in a clearance fit state with a slight gap. Also, a fixing pin 55 is installed on the second fitting portion 57 and the fitted portion 59.

[0075] Note that in 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 have a quadrangular prism shape with a square bottom surface.

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

[0077] As shown in Fig. 3, the ground 15 consists of a soft layer 63 composed of gravel, jade stones, and clay, etc., and a soft layer 63 composed of general earth and sand covering the soft layer 63. For example, the vertical hole 17 penetrates the soft layer 63, and all of the bottom 19 of the vertical hole 17 is located at the hard layer 65. Therefore, the diameter expansion using the under-reaming earth drill bucket 1 is carried out at the hard layer 65.

[0078] The earth drill 43 is installed on the ground 15, and holds, for example, the upper end of a cylindrical steel pipe (casing for excavation) 39, and is configured to move downward while rotating the held casing for excavation 39.

[0079] The width expansion wings 5 where the first excavation bit 25 and the second excavation bit 41 are installed are in a closed state, and the under-reaming earth drill bucket 1 is fixed to the casing for excavation 39 by the under-reaming earth drill bucket fixing part 33 and the under-reaming earth drill bucket rotation support part 35. Then, by rotating the casing for excavation 39 and moving it downward, the vertical hole 17 can be obtained.

[0080] As shown in Fig. 2 etc., the width expansion wing drive part 7 is composed of an actuator such as a hydraulic cylinder 67, a central member 69, an engagement member 71, and a pair of connecting members 73 (73A, 73B). The central member 69 is formed in a columnar shape such as a generally cylindrical shape, and extends downward from the central lower part of the stabilizer 3. The central axis of the central member 69 coincides with the first central axis C1. The central member 69 is integrally provided on the stabilizer 3. The second excavation bit 41 is integrally provided at the lower end of the central member 69.

[0081] The engagement member 71 is formed in an annular shape, and is provided on the central member 69 so that the central member 69 penetrates the inside of the ring. The engagement member 71 engages with the central member 69 so as to be movable in the vertical direction (the longitudinal direction of the central member 69; the extending direction of the central axis C1) with respect to the central member 69.

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

[0083] One end of the first connecting member 73A in the longitudinal direction is engaged with the engaging member 71. By this engagement, the first connecting member 73A rotates with respect to the engaging member 71 about the central axis C5 extending in the horizontal direction.

[0084] Also, the other end of the first connecting member 73A in the longitudinal direction is engaged with the first arm-like member 9A at the intermediate portion in the longitudinal direction of the first arm-like member 9A. By this engagement, the first connecting member 73A rotates with respect to the first arm-like member 9A about the central axis C6 extending in the horizontal direction.

[0085] One end of the second connecting member 73B in the longitudinal direction is engaged with the engaging member 71. By this engagement, the second connecting member 73B rotates with respect to the engaging member 71 about the central axis C7 extending in the horizontal direction.

[0086] Also, the other end of the second connecting member 73B in the longitudinal direction is engaged with the second arm-like member 9B at the intermediate portion in the longitudinal direction of the second arm-like member 9B. By this engagement, the second connecting member 73B rotates with respect to the second arm-like member 9B about the central axis C8 extending in the horizontal direction.

[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. Then, by allowing hydraulic oil to flow into the hydraulic cylinder 67 and also allowing the hydraulic oil to flow out of the hydraulic cylinder 67, the protruding length of the piston rod 79 from the cylinder body 75 changes.

[0088] The end of the cylinder body 75 is engaged with the first arm-shaped member 9A at the middle portion in the longitudinal direction of the first arm-shaped member 9A. By this engagement, the cylinder body 75 is adapted to rotate with respect to the first arm-shaped member 9A about the central axis C9 extending in the horizontal direction.

[0089] The end of the piston rod 79 is engaged with the second arm-shaped member 9B at the middle portion in the longitudinal direction of the second arm-shaped member 9B. By this engagement, the piston rod 79 is adapted to rotate with respect to the second arm-shaped member 9B about the central axis C10 extending in the horizontal direction.

[0090] With such a configuration, a limited linkage mechanism is formed by the stabilizer 3, the central member 69, the engagement member 71, the connecting member 73, and the hydraulic cylinder 67. When the protruding amount of the piston rod 79 from the cylinder body 75 is at the minimum value, the width-expanding wing 5 is in the closed state, and when the protruding amount of the piston rod 79 from the cylinder body 75 is at the maximum value, the width-expanding wing 5 is in the maximum open state.

[0091] Incidentally, in FIGS. 1 to 3 and FIG. 6(a), the bit installation body 13 for excavation is arranged in the longitudinal direction of the arm-shaped member 9, and the bit installation body 13 for excavation is installed only at the part below the width-expanding wing 5 (arm-shaped member 9). On the other hand, as shown in FIG. 6(b), the bit installation body 13 for excavation may be arranged in the longitudinal direction of the arm-shaped member 9 and installed over the entire length of the width-expanding wing 5 (arm-shaped member 9). Note that the reference numeral 26 in FIG. 2 and the like indicates a bit for excavation provided directly and integrally with the arm-shaped member 9.

[0092] The fixed part 33 of the under-reamed earth drill bucket is composed of a main body part 81, a pair of pad parts 83, and an extension part 85. The extension part 85 extends downward from the main body part 81. The pad parts 83 are supported by the main body part 81, and each of the pair of pad parts 83 is in contact with the inner surface of the casing 39 for excavation with a pressing force by the main body part 81. In a state where each of the pair of pad parts 83 is in contact with the inner surface of the casing 39 for excavation with a pressing force, the casing 39 for excavation, the pad part 83, the main body part 81, and the extension part 85 are integrated.

[0093] The rotary support part 35 of the under-reamed earth drill bucket is composed of a main body part 87 and an extension part 89. The lower end part of the extension part 85 of the fixed part 33 of the under-reamed earth drill bucket 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] And the main body part 87 can switch between a state where the extension part 89 is rotationally driven with respect to the main body part 87 and a state where the extension part 89 does not rotate with respect to the main body part 87 and is integrated with the main body part 87.

[0095] When each of the pair of pad parts 83 is in contact with the inner surface of the casing 39 for excavation with a pressing force and the extension part 89 is integrated with the main body part 87, the stabilizer 3 and the casing 39 for excavation are integrated. On the other hand, when each of the pair of pad parts 83 is in contact with the inner surface of the casing 39 for excavation with a pressing force, the state where the extension part 89 is rotationally driven with respect to the main body part 87 is defined as the rotational drive state. In this rotational drive state, the stabilizer 3 and the like rotate around the first central axis C1 with respect to the casing 39 for excavation.

[0096] As shown in FIG. 7, the adapter 45 is provided with a plurality of (for example, two) reinforcing members (reinforcing parts; play reducing parts) 91 in addition to the adapter main body 49, the first fitting part 51, and the second fitting part 57. The reinforcing member 91 is formed in an "L" shape. One end of the reinforcing member 91 is integrally joined to a predetermined part on the outer periphery of the cylindrical 51 or the adapter main body 49, for example, by 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] Thereby, compared with the case where the reinforcing member 91 is not provided, the play between the rotary propeller 47 and the stabilizer 3 in the rotational direction of the rotary propeller 47 and the stabilizer 3 can be reduced. That is, if the reinforcing member 91 is not provided, the play will occur between the first fitting part 51 and the fitted part 53, and between the second fitting part 57 and the fitted part 59. On the contrary, since the reinforcing member 91 is provided, the play between the second fitting part 57 and the fitted part 59 has disappeared. In addition, by providing the reinforcing member 91, the joint strength between the rotary propeller 47 and the reaming earth drill bucket 1 (stabilizer 3) can be improved.

[0098] Also, when viewed in the extending direction of the first central axis C1, the plurality of reinforcing members 91 are arranged at positions that scale the outer periphery of the cylindrical 51. That is, as shown in FIG. 7(a), a pair of reinforcing members 91 are provided, one reinforcing member 91 is arranged on the left side of the first fitting part 51, and the other reinforcing member 91 is arranged on the right side of the first fitting part 51. The reinforcing member 91 is provided with ribs 113 for increasing the rigidity of the reinforcing member 91.

[0099] The annular member 29 of the drilling bit installation body 13 is formed in an annular shape with a rectangular cross-section (cross-section by a plane orthogonal to the extending direction of the ring). The spiral member 31 of the drilling bit installation body 13 has a rectangular cross-section (cross-section by a plane orthogonal to the extending direction of the spiral).

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

[0101] Next, the formation of the vertical hole 17 and the operations of the underreaming earth drill bucket 1 and the like at the bottom 19 of the vertical hole 17 and the diameter expansion will be described.

[0102] In the initial state, a bit installation body 13 in which a first excavation bit 25 is installed on the widening wing 5 is installed, a second excavation bit 41 is installed on the underreaming earth drill bucket 1, and an earth drill 43 is disposed on the ground 15. In the initial state, the underreaming earth drill bucket 1 is integrally installed on the excavation casing 39 by the underreaming earth drill bucket fixing portion 33 and the underreaming earth drill bucket rotation support portion 35. In the initial state, the stabilizer 3 of the underreaming earth drill bucket 1 is integrated with the excavation casing 39. Also, in the initial state, the widening wing 5 is in a closed state, the excavation casing 39 and the underreaming earth drill bucket 1 are located on the ground 15, and the excavation casing 39 is installed on the earth drill 43.

[0103] In the above initial state, the earth drill 43 rotates the excavation casing 39 and moves it downward. Then, when the excavation casing 39 has been moved a predetermined distance, a columnar vertical hole 17 whose bottom 19 has not been expanded in diameter is obtained.

[0104] After that, the diameter of the bottom 19 of the vertical hole 17 is expanded. In this diameter expansion, the underreaming earth drill bucket fixing portion 33 is fixed to the excavation casing 39, and while rotating the widening wing 5 with the underreaming earth drill bucket rotation support portion 35, the widening wing drive portion 7 gradually opens the widening wing 5. By opening the widening wing 5 to the maximum open state, the diameter expansion of the bottom 19 of the vertical hole 17 is completed.

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

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

[0107] Working oil is supplied from a hydraulic source 105 to the first internal space 101 of the hydraulic cylinder 67. The pressure of the working oil supplied to the first internal space 101 is kept 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 (boring 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 the members 97 and 99 are rotated in the direction of arrow A1, the boring bit installation body 13 and the first boring bit 25 rotate in the direction of arrow A2, and the cut portion 111 of the ground 15 is cut, and the diameter of the bottom 19 of the vertical hole 17 is enlarged.

[0109] In the above description, the formation of the vertical hole 17 before enlarging the diameter of the bottom 19 and the enlargement of the diameter of the bottom 19 are performed using the under-reaming earth drill bucket 1. Instead, the formation of the vertical hole 17 before enlarging the diameter of the bottom 19 may be performed using a boring tool such as a drill, and then the diameter of the bottom 19 of the vertical hole 17 may be enlarged using the under-reaming earth drill bucket 1.

[0110] In the under-reaming earth drill bucket 1, a boring bit (first boring bit) 25 is installed on the widening wing 5 of the under-reaming earth drill bucket 1 using the boring bit installation body 13. The boring bit installation body 13 includes a boring bit installation body main body portion 21 supported by the widening wing 5 so as to rotate about the second central axis C2, and a plurality of boring bit installation portions 23 provided on the boring bit installation body main body portion 21 on which the first boring bit 25 is installed.

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

[0112] As a result, even if the bottom 19 of the vertical hole 17 is formed of the hard layer 65, it is difficult for the excavation bit 25 to get caught on the hard layer 65, and it is possible to avoid as much as possible the occurrence of a situation where the rotation of the widening wing 5 around the first central axis C1 stops. And even if the bottom 19 of the vertical hole 17 is formed of the hard layer 65, it is possible to expand the diameter in the hard layer 65, and it is possible to shorten the time required for expanding the diameter in the hard layer 65.

[0113] In the bottom-expanding earth drill bucket 1, a plurality of excavation-bit installation parts 23 are arranged along a plurality of first spirals extending on the outer peripheral part of the excavation-bit installation body main body part 21, and the plurality of first spirals are arranged in the circumferential direction of the excavation-bit installation body main body part 21.

[0114] As a result, looking at one excavation-bit installation body 13, for example, each of the plurality of excavation bits 25 excavates the hard layer 65 of the ground 15 with a time difference and continuously. That is, in a state of excavating the hard layer 65, at least one of the plurality of excavation bits 25 excavates the hard layer 65. And even if the bottom 19 of the vertical hole 17 is formed of the hard layer 65, the excavation-bit installation body 13 rotates smoothly around the second central axis C2, and the time required for diameter expansion can be further shortened.

[0115] In addition, in the expanded bottom earth drill bucket 1, the main body 21 of the bit installation body for excavation is composed of an annular member 29 and a plurality of spiral members 31. Each of the plurality of spiral members 31 has its first end joined to the first annular member 29A and its second end joined to the second annular member 29B. Each of the spiral members 31 is arranged at a position that equally distributes around the circumference of the annular member 29. Also, a plurality of bit installation parts 23 for excavation are provided on each of the plurality of spiral members 31. And the inside of the bit installation body 13 for excavation is hollowed out. Thus, it is easier to discharge the finely divided earth and sand generated by the excavation with the excavation bit 25.

[0116] In addition, in the expanded bottom earth drill bucket 1, when excavating the vertical hole 17, the widened wings 5 on which the first excavation bit 25 is installed are closed, and the expanded bottom earth drill bucket fixing part 33 is fixed to the excavation casing 39. Further, when excavating the vertical hole 17, the rotation of the widened wings 5 with respect to the excavation casing 39 is blocked by the expanded bottom earth drill bucket rotation support part 35, and the excavation casing 39 is rotated by the earth drill 43 and moved downward.

[0117] In addition, in the expanded bottom earth drill bucket 1, after finishing the excavation of the vertical hole 17, the expanded bottom earth drill bucket fixing part 33 is fixed to the excavation casing, and the widened wings 5 are rotated with respect to the excavation casing 39 by the expanded bottom earth drill bucket rotation support part 35. At this time, the widened wings 5 are gradually opened by the widened wing drive part 7.

[0118] Thereby, it is possible to excavate the vertical hole 17 with the expanded bottom earth drill bucket 1 and to expand the diameter of the bottom 19 of the excavated vertical hole 17.

[0119] Further, the adapter 45 includes an adapter main body portion 49 and a first fitting portion 51. The first fitting portion 51 is integrally provided on the upper side of the adapter main body portion 49 and is fitted to the fitted portion 53 of the rotary propelling body 47 so as to transmit the rotational force generated by the rotary propelling body 47 to the adapter main body portion 49 with reduced play.

[0120] Here, a plurality of types of adapters 45 with different dimensions of the first fitting portion 51 and the second fitting portion 57 are prepared. Then, when the dimensions of the fitted portion 53 of the rotary propelling body 47 of the earth drill 43 or the dimensions of the fitted portion 59 of the stabilizer 3 change, by using an appropriately selected adapter 45 from the plurality of types of adapters 45, the under-reaming earth drill bucket 1 can be joined to the rotary propelling body 47 of the earth drill 43 with almost no play.

[0121] Furthermore, the deviation of the under-reaming earth drill bucket 1 from the rotational center axis of the rotary propelling body 47 of the earth drill 43 can be minimized as much as possible, and a vertical hole 17 with an accurate shape and the bottom 19 of the vertical hole 17 can be enlarged in diameter to an accurate shape.

[0122] Here, the above-described content may be understood as a method for constructing an under-reamed hole.

[0123] That is, a method for constructing an under-reamed hole using an under-reamed earth drill bucket 1 in which a drilling bit 41 is provided at the lower end of an expanding wing 5. The method includes closing the expanding wing where the first drilling bit is installed, fixing the under-reamed earth drill bucket fixing portion to the drilling casing, preventing the rotation of the expanding wing with respect to the drilling casing by the under-reamed earth drill bucket rotation support portion, rotating and moving the drilling casing downward to excavate the ground and provide a vertical hole in a vertical hole excavation step. After finishing the excavation of the vertical hole in the vertical hole excavation step, fixing the under-reamed earth drill bucket fixing portion to the drilling casing, and while rotating the expanding wing with respect to the drilling casing by the under-reamed earth drill bucket rotation support portion, gradually opening the expanding wing by the expanding wing drive portion to expand the diameter of the bottom of the vertical hole, which may be understood as a method for constructing an under-reamed hole having a vertical hole bottom diameter expansion step.

[0124] The above describes the present embodiment, but the present embodiment is not limited thereto, and various modifications are possible within the scope of the gist of the present embodiment.

Explanation of reference numerals

[0125] 1 Under-reamed earth drill bucket 3 Stabilizer 5 Expanding wing 7 Expanding wing drive portion 9, 9A, 9B Arm-like members 11 Installation portion of drilling bit installation body 13 Drilling bit installation body 15 Ground 17 Vertical hole 19 Bottom 21 Main body portion of drilling bit installation body 23 Drilling bit installation portion 25 First drilling bit 29, 29A, 29B Annular members 31 Spiral member 33 Under-reamed earth drill bucket fixing portion 35 Under-reamed earth drill bucket rotation support portion 39 Casing for excavation 41 Second bit for excavation 45 Adapter 47 Rotary drive body (Kelly bar) 49 Adapter main body 51 First fitting part 53 Fitted part (fitted part of rotary drive body) 57 Second fitting part 59 Fitted part (fitted part of stabilizer) 91 Reinforcing member C1 First central axis C2 Second central axis

Claims

1. A bit installation body for excavation installed on an expanding wing composed of a stabilizer that rotates about a first central axis to expand the bottom of a vertical hole dug in the ground, and an arm-shaped member that is formed in a rod shape and has an upper end rotatably engaged with the stabilizer, wherein a main body portion of the bit installation body for excavation is supported by the expanding wing so as to rotate about a second central axis extending in a direction parallel to the longitudinal direction of the arm-shaped member, a plurality of bit installation portions for excavation are provided on the main body portion of the bit installation body for excavation, and one first excavation bit is installed in each of the plurality of bit installation portions for excavation. The bit installation body for excavation is configured as such.

2. The plurality of bit installation portions for excavation are arranged along a plurality of spirals extending on the outer peripheral portion of the main body portion of the bit installation body for excavation with the second central axis as the central axis. There are a plurality of the spirals, and the plurality of spirals are arranged in the circumferential direction of the main body portion of the bit installation body for excavation. The bit installation body for excavation according to Claim 1.

3. The main body portion of the bit installation body for excavation is configured to include a pair of annular members and a plurality of spiral members, the central axes of these two annular members coincide with the second central axis, and they are separated by a predetermined distance in the extending direction of the central axis of the annular member, one end in the longitudinal direction of each of the plurality of spiral members is joined to one of the pair of annular members, and the other end in the longitudinal direction is joined to the other of the pair of annular members, the central axis of the spiral of the spiral member coincides with the second central axis, and the number of turns of the spiral in the spiral member is 0.1 or more and 1 or less, the plurality of spiral members are arranged at positions equally distributing around the circumference of the annular member, the plurality of bit installation portions for excavation are provided on each of the plurality of spiral members and are arranged at a predetermined interval in the extending direction of the spiral member. The bit installation body for excavation according to Claim 2.

4. The stabilizer and The widening wings are composed of a pair of the arm-like members, and a first arm-like member which is one of the pair of arm-like members is rotatably engaged with the stabilizer at the upper end portion in the longitudinal direction thereof, and a second arm-like member which is the other of the pair of arm-like members is rotatably engaged with the stabilizer at the upper end portion in the longitudinal direction thereof, and the widening wings provided with a bit installation portion for an excavation bit where the bit installation body for an excavation bit according to any one of claims 1 to 3 is installed, a widening wing drive portion for rotating the pair of arm-like members with respect to the stabilizer, a reaming earth drill bucket having the above.

5. a reaming earth drill bucket fixing portion fixed to an excavation casing forming a wall portion of the vertical hole, a reaming earth drill bucket rotation support portion supported by the reaming earth drill bucket fixing portion, and rotating the widening wings with respect to the excavation casing in a state where the reaming earth drill bucket fixing portion is fixed to the excavation casing, or preventing the widening wings from rotating with respect to the excavation casing in a state where the reaming earth drill bucket fixing portion is fixed to the excavation casing, The reaming earth drill bucket according to claim 4, having the above.

6. comprising a second excavation bit provided at a lower end of the widening wings, When excavating the vertical hole, closing the widening wings where the first excavation bit is installed, fixing the reaming earth drill bucket fixing portion to the excavation casing, and preventing the widening wings from rotating with respect to the excavation casing by the reaming earth drill bucket rotation support portion, rotating and moving the excavation casing downward, After finishing the excavation of the vertical hole, fixing the reaming earth drill bucket fixing portion to the excavation casing, and while rotating the widening wings with respect to the excavation casing by the reaming earth drill bucket rotation support portion, gradually opening the widening wings by the widening wing drive portion. The reaming earth drill bucket according to claim 5, configured as above.

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