Expanded-bottom bucket

Abstract

This invention provides a wide-bottom bucket that can be made lighter by reducing the shaft diameter of the bucket body. [Solution] This is a widened-bottom bucket 1 for forming a widened-bottom portion at the bottom of a pile, with a diameter larger than that of the shaft portion. The device comprises a cylindrical main body 11 and an expanding wing portion 12 that is formed to be openable in order to increase the diameter of the main body. Furthermore, a protruding wing portion 121 is formed at the lower part of the side end of the expanding wing portion, which protrudes outward when the device is closed relative to the main body.

Description

Technical Field

[0001] The present invention relates to an under-reamed bucket for forming an under-reamed portion having a diameter larger than that of a shaft portion at the bottom of a pile.

Background Art

[0002] As disclosed in Patent Documents 1 and 2, an under-reamed pile as a cast-in-place concrete pile provided with an under-reamed portion having a diameter larger than that of a shaft portion at the bottom of the pile is known. This under-reamed pile is constructed by excavating the ground with an excavator to form a portion that becomes the shaft portion, and then gradually expanding and cutting a portion that becomes the under-reamed portion with an under-reamed bucket below it to form an under-reamed portion having a diameter larger than that of the shaft portion.

[0003] As disclosed in Patent Documents 1 and 2, the main body portion of the under-reamed bucket is formed in a cylindrical shape having substantially the same diameter as the shaft portion of the under-reamed pile, and the excavation of the under-reamed portion is performed by opening the widening wings that are housed in the main body portion in a closed state.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, when the main body portion is manufactured according to the diameter of the shaft portion of the under-reamed pile, the weight of the under-reamed bucket increases and the shaft diameter also becomes larger. In particular, when the shaft diameter of the under-reamed bucket exceeds 2300 mm, it can only be transported by a special vehicle, which makes the construction conditions severe and also a factor causing an increase in construction costs.

[0006] Therefore, the present invention aims to provide a wide-bottom bucket that can be made lighter by reducing the shaft diameter of the bucket body. [Means for solving the problem]

[0007] To achieve the above objective, the widened-base bucket of the present invention is a widened-base bucket for forming a widened-base portion with a diameter larger than that of the shaft portion at the bottom portion of a pile, comprising a cylindrical body portion and a widening wing portion formed to be openable so as to enlarge the diameter of the body portion, characterized in that a protruding wing portion is formed at the lower part of the side end of the widening wing portion, which protrudes outward when closed relative to the body portion.

[0008] Here, the protruding wing portion is a part of the widening wing portion and can be configured to be trapezoidal or pentagonal in a side view. Furthermore, the amount of protrusion of the protruding wing portion is preferably 5%-35% of the radius of the main body portion. [Effects of the Invention]

[0009] In the widened-base bucket of the present invention configured in this way, the lower part of the side end of the widened wing portion becomes a protruding wing portion that protrudes outward when it is closed relative to the main body. With this configuration, even if the widened base diameter of the widened-base pile is large, the shaft diameter of the bucket's main body can be kept down.

[0010] By making the shaft diameter of the main body smaller than usual, it becomes possible to lighten the expanded-base bucket. Reducing the weight and shaft diameter of the expanded-base bucket makes it easier to transport and handle at construction sites, and also reduces construction costs. [Brief explanation of the drawing]

[0011] [Figure 1] This is an explanatory diagram showing the schematic configuration of the widened-bottom bucket of this embodiment. [Figure 2] This is an explanatory diagram showing the widened wings of the widened-base bucket fully extended. [Figure 3]This is a plan view illustrating the open and closed states of the widened-bottom bucket. [Figure 4] This diagram illustrates the expanded-bottom bucket of this embodiment in comparison with a conventional expanded-bottom bucket. [Figure 5] This is an explanatory diagram showing the schematic configuration of the widened-bottom bucket of Example 1. [Modes for carrying out the invention]

[0012] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Figure 1 is a side view illustrating the schematic configuration of the widened-bottom bucket 1 of this embodiment. Figure 2 is an explanatory diagram showing the widened-bottom bucket 1 with its widened wings 12 fully open.

[0013] The enlarged-base bucket 1 of this embodiment is used when constructing an enlarged-base pile. An enlarged-base pile mainly consists of a shaft portion that is cylindrical in shape and has a predetermined diameter from the ground, and an enlarged-base portion that is formed below the shaft portion with a larger diameter than the shaft portion.

[0014] Enlarged-base piles are cast-in-place concrete piles constructed by installing steel materials such as reinforcing cages into holes excavated in the ground and then pouring concrete. The enlarged base mainly consists of a truncated cone-shaped section that widens from the lower end of the shaft and a vertical section that forms a cylindrical shape below it.

[0015] The widened-base bucket 1 used when constructing such widened-base piles comprises a cylindrical body portion 11 and two widening wing portions 12, 12 that are formed to be openable in order to increase the diameter of the body portion 11, as shown in Figures 1 and 2.

[0016] This widened-base bucket 1 is a device that is attached to an earth drill (not shown), and more specifically, is detachably attached via a connecting flange 141 to the lower end of the Kelly bar of an earth drill which is equipped with a slewing body, boom, Kelly rope, Kelly bar, etc.

[0017] The main body 11 of the bottom-expanded bucket 1 is formed to have a diameter that can be inserted into an excavation hole excavated by an excavation bucket (not shown), and an annular stabilizer 3 is arranged at the upper part.

[0018] And, as will be described later, the main body 11 of the bottom-expanded bucket 1 of the present embodiment is formed in a cylindrical shape with a diameter smaller than the shaft diameter of a conventional bucket. Here, the "cylindrical shape" does not refer to a cylindrical shape in which a continuous circumferential surface in a cylindrical shape is formed only by the main body 11, but refers to a shape similar to a cylindrical shape in which parts such as the locations where the two widened wing parts 12, 12 are accommodated are open.

[0019] That is, the widened wing part 12 is closed when the bottom-expanded bucket 1 is lifted, forming a part of the side surface of the cylindrical main body 11 (see FIG. 1), and is opened when inserted into the excavation hole to cut and widen the wall surface of the excavation hole (see FIG. 2).

[0020] As shown in FIG. 2 in a side view, the widened wing part 12 is formed with an equal-width part having a substantially constant width near the lower end, and a triangular part in a right-angled triangular shape that tapers upward from that part. Also, as shown in FIG. 3 in a plan view, it is formed in an arc shape.

[0021] Inside the main body 11, a transmission shaft part 14 connected via a connecting flange 141 to the lower end of the kelly bar of an earth drill is accommodated. At the lower end of this transmission shaft part 14, the upper end of a connecting member (not shown) for applying a force to open and close the widened wing part 12 is connected in a bendable manner by a universal joint structure.

[0022] At the side end part of the widened wing part 12, blade parts 122 such as bits for cutting the ground are provided at intervals in the extending direction of the side end part. And the part cut by the blade part 122 at the side end part that becomes the hypotenuse of the triangular part becomes the part that spreads in a frustum of a cone shape at the expanded bottom part of the end-bearing pile.

[0023] On the other hand, the equal-width section of the widened wing 12 is formed to a height of, for example, about 500 mm, and the portion cut by this equal-width section becomes the vertical part of the widened base section with a thickness of about 500 mm. Furthermore, the bottom of the widened wing 12 (the lower end surface of the equal-width section) can be formed to slope upward toward the outer edge, as shown in Figure 2, or it can be formed to be approximately horizontal.

[0024] Figure 3 is a plan view illustrating the open and closed states of the widened-bottom bucket 1. As shown in Figures 3 and 1, the widened-bottom bucket 1 of this embodiment is formed such that the lower part of the side end of the widened wing portion 12 becomes a protruding wing portion 121 that protrudes radially outward when it is closed relative to the main body portion 11.

[0025] Looking at the side view of Figure 1, it can be seen that the protruding wing portion 121 protrudes outward in a trapezoidal shape. In other words, the protruding wing portion 121 is a plate-like member that is integral with the steel plate or the like that forms the main body of the widening wing portion 12, and refers to the part that protrudes outward from the main body portion 11. In short, the protruding wing portion 121 is a part of the widening wing portion 12.

[0026] For example, in the conventional widened-bottom bucket a shown in the upper part of Figure 4, when the widened wing portion a2 is closed relative to the main body portion a1, the tip of the widened wing portion a2 is positioned in a continuous position with the main body portion a1 and does not protrude.

[0027] In contrast, in the widened-bottom bucket 1 of this embodiment shown in Figure 3, the protruding wing portion 121 of the widening wing portion 12 protrudes radially outward from the main body portion 11. In short, in the conventional widened-bottom bucket a, the widening wing portion a2 is attached with a width that matches the shaft diameter of the main body portion a1, but in the widened-bottom bucket 1 of this embodiment, the widening wing portion 12 is attached with a width that is wider than the shaft diameter of the main body portion 11.

[0028] In detail, D1 shown in Figure 3 is the shaft diameter (diameter) of the main body 11. D2 is the diameter required to allow the widened-base bucket 1, which passes through the outermost tip in a plan view when the widened-base wing 12 is closed, to pass through. This diameter D2 is approximately equal to the diameter of the shaft of the widened-base pile.

[0029] Then, D3 becomes the diameter of the enlarged base of the enlarged base pile that can be excavated by the fully opened widened wing section 12 (enlarged base diameter). For example, when constructing an enlarged base pile with a shaft diameter D2 of about 2400 mm and an enlarged base diameter D3 of about 6000 mm, the shaft diameter D1 of the main body section 11 can be set to about 2000 mm.

[0030] At this time, the amount of protrusion of the protruding wing portion 121 (radial protrusion length) is approximately 200 mm (= (D2 - D1) / 2 = (2400 - 2000) / 2). In other words, the ratio of the amount of protrusion to the radius of the main body portion 11 (D1 / 2) is approximately 20% (= 200 / 1000). From this, it can be said that it is preferable to set the amount of protrusion of the protruding wing portion 121 to 5%-35% of the radius of the main body portion 11.

[0031] Figure 4 is an explanatory diagram comparing the widened-base bucket 1 of this embodiment with a conventional widened-base bucket a. In both widened-base buckets (1,a), the diameter of the shaft portion of the widened-base pile into which it is inserted is the same, and the widened-base diameter of the widened-base portion is also the same.

[0032] On the other hand, in the conventional widened-base bucket a, the main body a1 is formed to have approximately the same diameter as the shaft of the widened-base pile, resulting in a weight of approximately 8.8 tons. In contrast, the widened-base bucket 1 of this embodiment is manufactured so that the shaft diameter of the main body 11 is smaller than that of the conventional main body a1.

[0033] Therefore, the weight of the widened-bottom bucket 1 in this embodiment can be kept to approximately 6.3 tons. In other words, it is lighter than the conventional widened-bottom bucket a by approximately 2.5 tons (about 30%).

[0034] Furthermore, the expanded-bottom bucket 1 of this embodiment has an axis diameter of the main body 11 that is about 20% smaller than the axis diameter of the conventional main body a1, which is advantageous during transportation. As mentioned above, if the axis diameter of the bucket exceeds 2300 mm, it can only be transported by special vehicles, but with the expanded-bottom bucket 1 of this embodiment, even if the expanded-bottom diameter is the same, it can be transported by a smaller vehicle.

[0035] Next, a method for constructing an enlarged-base pile using the enlarged-base bucket 1 of this embodiment will be described. First, a drilling bucket (not shown in the diagram) is attached to the lower end of the earth drill's Kelly bar to construct a cylindrical drill hole.

[0036] Then, the drilling bucket is lifted out of the borehole and detached from the Kelly bar, and the widened-bottom bucket 1 is attached to the lower end of the Kelly bar in its place.

[0037] In this state, the widened-bottom bucket 1 is lowered into the borehole, and the tip portion 13, which will be the underside of the widened-bottom bucket 1, is brought into contact with the bottom of the borehole. Next, when the earth drill is driven and the Kelly bar is rotated, the widened-bottom bucket 1 begins to rotate due to the transmitted rotational force.

[0038] When the lower surface of the widened-bottom bucket 1 is in contact with the bottom of the excavation hole, the main body 11 of the widened-bottom bucket 1 cannot be lowered any further. In contrast, the transmission shaft 14, which transmits the weight of the Kelly bar, can be lowered along the guide cylinder (not shown).

[0039] When only the transmission shaft portion 14 descends while the main body portion 11 does not descend, the lower end of the connecting member (not shown), which is flexibly connected to the lower end of the transmission shaft portion 14, spreads outwards, causing the two widening wing portions 12, 12 to open slightly.

[0040] Blades 122 are provided at the side ends of the widening wing section 12, which cut the excavation wall surface. As the excavation wall surface is cut, the widening wing section 12 becomes more likely to spread outward, and as the Kelly bar rotates, the widening bucket 1 rotates, and the opening of the widening wing section 12 gradually increases, ultimately forming a widened excavation hole in which a widened base is constructed (see Figures 2 and 3).

[0041] Meanwhile, the widened excavated soil generated during this widening excavation is gathered into the main body 11 by the rotating widening wings 12, 12. When the Kelly bar is lifted, the transmission shaft 14 rises, the connecting member connected to the transmission shaft 14 rises, and the widening wings 12 close.

[0042] If the lifting of the Kelly bar continues in this state, the main body 11 will be lifted. The expanded-bottom bucket 1, which has the excavated soil contained inside, is then moved to the soil disposal site, and when the lid of the tip 13 is opened, the excavated soil is discharged from the expanded-bottom bucket 1.

[0043] By repeatedly removing excavated soil using the enlarged-base bucket 1, and once the soil and sand have been completely removed from the bottom of the excavation hole, a reinforcing cage is inserted and concrete is poured to complete an enlarged-base pile made of cast-in-place concrete.

[0044] Next, the operation of the widened-bottom bucket 1 in this embodiment will be described. In this configuration, the widened-base bucket 1 of this embodiment has a protruding wing portion 121 that protrudes outward when the lower part of the side end of the widened wing portion 12 is closed relative to the main body portion 11. With this configuration, even if the widened base diameter of the widened-base pile is large, the shaft diameter of the main body portion 11 of the widened-base bucket 1 can be kept down.

[0045] For example, compared to a conventional wide-bottom bucket a as shown in the upper part of Figure 4, the wide-bottom bucket 1 of this embodiment can reduce weight by about 30%, and the shaft diameter of the main body 11 can be reduced by about 20%.

[0046] By making the shaft diameter of the main body 11 smaller than usual, it becomes possible to lighten the expanded-bottom bucket 1. Reducing the weight and shaft diameter of the expanded-bottom bucket 1 makes it easier to transport and handle at construction sites, and also reduces construction costs. [Examples]

[0047] Hereinafter, a different form of the expanded-bottom bucket 1A from the expanded-bottom bucket 1 of the above-described embodiment will be described with reference to Figure 5. Parts that are the same or equivalent as those described in the above embodiment will be denoted by the same reference numerals.

[0048] As shown in Figure 5, the widened-bottom bucket 1A described in this embodiment 1 comprises a cylindrical body portion 11 and two widening wing portions 12A, 12A that are formed to be openable in order to increase the diameter of the body portion 11.

[0049] As shown in Figure 5 when viewed from the side, the widened wing section 12A has a section with a nearly constant width near its lower end, and a trapezoidal section that tapers above it. In other words, unlike the widened wing section 12 (see Figure 2) described in the above embodiment, the upper end surface 123 of the widened wing section 12A is formed near the stabilizer 3 of the widened bucket 1A.

[0050] Furthermore, the main body of the widened wing section 12A is provided with multiple openings 124. By providing these openings 124 in the widened wing section 12A, an even lighter widened-bottom bucket 1A can be made.

[0051] Furthermore, by removing the portion of the widened wing section 12A that protrudes above the stabilizer 3, further weight reduction can be achieved, and the height of the widened bucket 1A can also be reduced, resulting in improved handling performance during transport and at construction sites.

[0052] Furthermore, the other configurations and effects are substantially the same as those of the above-described embodiment, so their explanation will be omitted.

[0053] While embodiments and examples of the present invention have been described in detail above with reference to the drawings, the specific configuration is not limited to these embodiments and examples, and any design modifications that do not depart from the spirit of the present invention are included in the present invention.

[0054] For example, the widened wing portions 12, 12A of the widened-bottom buckets 1, 1A described above had trapezoidal protruding wing portions 121 in side view, but this is not limited to this, and the protruding wing portions can also be pentagonal or other polygonal shapes, such as irregular pentagons, in side view. [Explanation of symbols]

[0055] 1,1A: Wide-bottom bucket 11: Main body 12,12A: Widened wing section 121:Protruding wing part

Claims

1. An enlarged-base bucket for forming an enlarged base portion at the bottom of a pile, with a diameter larger than that of the shaft portion, A cylindrical main body, The main body comprises an expandable wing portion formed to be openable so as to increase the diameter of the main body, A widened-bottom bucket characterized in that a protruding wing portion is formed at the lower part of the side end of the widened wing portion, which protrudes outward when the bucket is closed relative to the main body portion.

2. The widened-bottom bucket according to claim 1, characterized in that the protruding wing portion is a part of the widened-wing portion and is formed in a trapezoidal or pentagonal shape when viewed from the side.

3. The widened-bottom bucket according to claim 1 or 2, characterized in that the amount of protrusion of the protruding wing portion is 5% to 35% of the radius of the main body portion.

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