Rotary pile joint protection structure

Abstract

To improve workability and suppress friction of a joint structure by reducing the resistance arising from ground resistance during installing in a mechanical joint structure having a part protruding outward from an outer peripheral surface of a steel pipe in a rotary pile.SOLUTION: The present invention discloses a joint protection structure for rotary piles, which is a joint protection structure provided adjacent to a mechanical joint structure for rotary piles, wherein the mechanical joint structure includes a part formed at an end of the rotary pile and protruding outward from the outer peripheral surface of the rotary pile, and the joint protection structure comprises a plurality of ribs protruding outward in a radial direction of the rotary pile and arranged in a circumference direction of the rotary pile.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a joint protection structure for a rotary pile. [Background technology]

[0002] Patent Document 1 describes a rotary pile joint structure including a pair of end plates fixed to the ends of a rotary pile made of a steel pipe, and a shear resistance portion provided on each end plate to resist the rotary shear force of the rotary pile. A joint that transmits the rotary shear force of the rotary pile mainly by mechanical means rather than welding is also called a mechanical joint structure. Such a mechanical joint structure for a rotary pile is advantageous in that it does not require welding on site and simplifies the construction process of the rotary pile.

[0003] In the mechanical joint structure of a rotary pile, a member formed at the end of a steel pipe may protrude outward beyond the outer diameter of the steel pipe. For example, in the case of Patent Document 1, an end plate protrudes like a flange from the outer circumferential surface of the rotary pile, and the protruding parts are bolted together to maintain the jointed state of both rotary piles, thereby maintaining the engagement between the engagement hole formed in the end plate at the part corresponding to the inside of the rotary pile and the engagement member. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2019 / 111882 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the overhanging portion provided for the functional necessity of the mechanical joint structure as described above may become a resistance to concrete driving during construction. Specifically, for example, in a ground having a soft layer below a hard layer, when the vaned tip of the rotary pile reaches the soft layer while the intermediate joint structure is located in the hard layer, the driving force of the vaned tip in the soft layer in the driving direction of the rotary pile is small, while the resistance received by the joint structure including the overhanging portion in the hard layer is large. In this case, in addition to the construction time until the joint structure passes through the hard layer being long, the joint structure may be worn or damaged due to contact with the ground for a long time.

[0006] Therefore, the present invention aims to provide a joint protection structure for a rotary pile that uses a mechanical joint structure in a rotary pile that has a portion that protrudes outward from the outer circumferential surface of the steel pipe, thereby reducing the resistance caused by the resistance of the ground during driving, thereby improving workability and suppressing wear of the joint structure. [Means for solving the problem]

[0007] [1] A joint protection structure provided adjacent to a mechanical joint structure of a rotary pile, the mechanical joint structure being formed at an end of the rotary pile and having a portion that protrudes outwardly beyond the outer peripheral surface of the rotary pile, and the joint protection structure being provided with a plurality of ribs that protrude radially outwardly from the rotary pile and are arranged circumferentially of the rotary pile. [2] The joint protection structure for a rotary pile described in [1] further includes a strip-shaped member joined to the outer peripheral surface of the rotary pile at a position adjacent to the mechanical joint structure, and the multiple ribs protrude from the outer peripheral surface of the strip-shaped member. [3] A joint protection structure for a rotary pile described in [1] or [2], in which the ends of the plurality of ribs opposite the mechanical joint structure are tapered. [4] The mechanical joint structure is a joint protection structure for a rotary pile described in any one of [1] to [3], comprising: an end plate joined to the end of the rotary pile, the outer circumferential portion of which forms a flange-like portion protruding outward from the outer circumferential surface of the rotary pile; an engaging member engaged with an engaging hole formed in a portion of the end plate corresponding to the inside of the rotary pile; and a bolt inserted into each of a plurality of bolt holes formed in the flange-like portion. [5] A joint protection structure for a rotary pile described in [4], wherein the engagement hole is polygonal when viewed in cross section of the rotary pile, and at least a portion of the multiple ribs are positioned in a position that does not overlap with the corners of the polygon in the circumferential direction of the rotary pile. [6] The mechanical joint structure includes a sleeve pipe that is placed over the end of the rotary pile or a joint member joined to the end of the rotary pile. A joint protection structure for a rotary pile described in any one of [1] to [3]. [7] A joint protection structure for a rotary pile described in any one of [1] to [6], wherein the plurality of ribs are positioned away from the mechanical joint structure. [8] The joint protection structure for a rotary pile described in [7], further comprising an intermediate flange joined to the outer peripheral surface of the rotary pile, and the ends of the plurality of ribs on the mechanical joint structure side are joined to the intermediate flange. [9] A joint protection structure for a rotary pile described in [4] or [5], wherein the ends of the plurality of ribs on the mechanical joint structure side are joined to the end plate. Effect of the Invention

[0008] According to the above configuration, the multiple ribs provided as the joint protection structure adjacent to the mechanical joint structure function as drilling bits, so that the ground near the outer circumferential surface of the rotary pile is loosened by drilling in the vicinity of the mechanical joint structure when the rotary pile is driven. Therefore, the mechanical joint structure reduces the resistance caused by the resistance of the ground when driving the rotary pile, thereby improving workability and suppressing wear of the joint structure. [Brief description of the drawings]

[0009] [Figure 1]1 is a diagram showing an end portion of a rotary pile provided with a joint protection structure according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is a cross-sectional view taken along line II-II in FIG. [Diagram 3] FIG. 2 is a cross-sectional view taken along line III-III in FIG. [Figure 4] FIG. 11 is a diagram showing an end portion of a rotary pile provided with a joint protection structure according to a second embodiment of the present invention. [Diagram 5] 5 is a view taken along line VV in FIG. 4. [Figure 6] FIG. 11 is a diagram showing a connecting portion of a rotary pile provided with a joint protection structure according to a third embodiment of the present invention. [Figure 7] FIG. 13 is a diagram showing a connecting portion of a rotary pile provided with a joint protection structure according to a fourth embodiment of the present invention. [Figure 8] FIG. 13 is a diagram showing a connecting portion of a rotary pile provided with a joint protection structure according to a fifth embodiment of the present invention. [Figure 9] 9 is a cross-sectional view taken along line IX-IX in FIG. 8. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In this specification and the drawings, components having substantially the same functional configurations are designated by the same reference numerals, and redundant explanations will be omitted.

[0011] (First embodiment) FIG. 1 is a view showing an end of a rotary pile provided with a joint protection structure according to a first embodiment of the present invention, FIG. 2 is a view taken along line II-II in FIG. 1, and FIG. 3 is a view taken along line III-III in FIG. 1. In this embodiment, the mechanical joint structure of the rotary pile 1 includes an end plate 2 joined to the end of the rotary pile 1, an engagement hole 21 and a bolt hole 22 formed in the end plate 2, an engagement member (not shown) engaged with the engagement hole 21, and a bolt (not shown) inserted into the bolt hole 22. The outer peripheral portion of the end plate 2 is a flange-shaped portion that protrudes outward from the outer peripheral surface of the rotary pile 1. The engagement hole 21 is formed in a portion of the end plate 2 that corresponds to the inner side of the rotary pile 1. The engagement hole 21 and the engagement member have a polygonal shape (hexagonal in the illustrated example) when viewed in cross section of the rotary pile 1. On the other hand, the bolt holes 22 are arranged in the circumferential direction of the rotary pile 1 in the flange-shaped portion of the end plate 2.

[0012] The mechanical joint structure of the rotary pile is, for example, a structure as shown in Figures 9A to 9C of International Publication No. 2019 / 111882. Specifically, the engagement member engaged with the engagement hole 21 is also engaged with an engagement hole formed in another rotary pile to be connected. Since the engagement hole 21 and the engagement member have corresponding polygonal shapes, the respective members mesh with each other at the corners of the polygon, and the torque of the rotary pile is transmitted. By fastening the flange-shaped portions of the end plates of both rotary piles with bolts inserted into the bolt holes 22, the state in which the engagement members are engaged with the engagement holes 21 is maintained, and the torque of the rotary pile can be stably transmitted.

[0013] In addition to the mechanical joint structure of the rotary pile as described above, a joint protection structure is provided. Specifically, the joint protection structure includes a strip-shaped member 3 joined to the outer peripheral surface of the rotary pile 1 at a position adjacent to the end plate 2 constituting the mechanical joint structure, and a plurality of ribs 4 protruding from the outer peripheral surface of the strip-shaped member 3 radially outward from the rotary pile 1. Here, the strip-shaped member 3 is a member having a width in the axial direction of the rotary pile 1. The plurality of ribs 4 are arranged in the circumferential direction of the rotary pile 1, and each rib 4 has a shape extending in the axial direction of the rotary pile 1. When the rotary pile 1 penetrates into the ground while rotating, such a rib 4 functions as an excavation bit that excavates the ground near the outer peripheral surface of the rotary pile 1 prior to the mechanical joint structure including the end plate 2.

[0014] In this embodiment, by providing a joint protection structure including the rib 4 as described above, the ground near the outer circumferential surface of the rotary pile 1 is loosened by excavation near the mechanical joint structure when the rotary pile 1 is driven. Therefore, the resistance received by the flange-shaped portion of the end plate 2 protruding outward from the outer circumferential surface of the rotary pile 1 and the bolt inserted into the bolt hole 22 formed in this flange-shaped portion is reduced, and improvement of workability and suppression of wear of the joint structure can be realized. By making the end portion of the rib 4 opposite to the end plate 2 into a tapered shape, it becomes easier for the rib 4 to penetrate into the ground while excavating the ground. The strip-shaped member 3 functions as a reinforcing member of the rotary pile 1 in the portion where the rib 4 is provided, and prevents the rotary pile 1 from being deformed or damaged by the reaction force when the rib 4 excavates the ground. For example, if the pipe thickness of the rotary pile 1 is sufficient, the strip-shaped member 3 does not necessarily have to be provided.

[0015] As described above, in the joint protection structure, the band-shaped member 3 and the rib 4 of the joint protection structure are disposed adjacent to the end plate 2, but this does not necessarily mean that there is no gap between the band-shaped member 3 and the rib 4 and the end plate 2. In the example shown in FIG. 1, the band-shaped member 3 and the rib 4 are disposed away from the end plate 2 (but close to the end plate 2). With such an arrangement, the soil excavated by the rib 4 may be retained between the end plate 2 and the rib 4, and the resistance received by the mechanical joint structure may be more effectively reduced. In another example, the band-shaped member 3 and the rib 4 may be disposed closer to the end plate 2. In the illustrated example, the rib 4 overlaps with the bolt hole 22 in the circumferential direction of the rotary pile 1, so that the rib 4 needs to be separated from the end plate 2 by the clearance of the bolt inserted into the bolt hole 22. However, in another example, when the rib 4 does not overlap with the bolt hole 22, the rib 4 may be brought even closer to the end plate 2, and in this case, the rib 4 may be joined to the end plate 2.

[0016] 3, in this embodiment, the rib 4 is disposed at a position that does not overlap with the corners of the polygon of the engagement hole 21 in the circumferential direction of the rotary pile 1. As described above, the torque of the rotary pile 1 is transmitted by the engagement between the engagement hole 21 and the engagement member at the corners of the polygon of the engagement hole 21, and therefore local stress occurs near the corners. By not overlapping the attachment position of the rib 4 with the corners of the polygon of the engagement hole 21 in the circumferential direction of the rotary pile, it is possible to prevent interference between the local stress due to the reaction force when the rib 4 excavates the ground and the local stress due to the transmission of the torque.

[0017] Second embodiment Fig. 4 is a diagram showing an end portion of a rotary pile provided with a joint protection structure according to a second embodiment of the present invention, and Fig. 5 is a view taken along line VV in Fig. 4. In this embodiment, the joint protection structure includes an intermediate flange 5 in addition to the belt-shaped member 3 and the rib 4. In other respects, the configuration of this embodiment is similar to that of the first embodiment described above, and therefore repeated detailed explanations will be omitted.

[0018] The intermediate flange 5 is joined to the outer circumferential surface of the rotary pile 1 on the side of the joint protection structure closer to the end plate 2. The intermediate flange 5 is disposed away from the end plate 2 by, for example, the clearance of the bolt inserted into the bolt hole 22, but the entire joint protection structure including the intermediate flange 5 is adjacent to the mechanical joint structure including the end plate 2, as in the above-mentioned first embodiment. In this embodiment, the end of the rib 4 on the end plate 2 side is joined to the intermediate flange 5. This reinforces the rib 4 and also pushes the soil excavated by the rib 4 out beyond the intermediate flange 5, making it easier for the mechanical joint structure including the end plate 2 to pass through the soil.

[0019] (Third embodiment) FIG. 6 is a diagram showing a connecting portion of a rotary pile provided with a joint protection structure according to a third embodiment of the present invention. In this embodiment, the mechanical joint structure includes a joint member 6 joined to the end of the rotary pile 1 and a sleeve pipe 7 covered on the joint member 6. A threaded portion is formed on the outer peripheral surface of the joint member 6 and the inner peripheral surface of the sleeve pipe 7. The rotary pile 1 and another rotary pile 9 joined to the joint member 8 are connected by screwing another joint member 8 to the sleeve pipe 7 screwed to the joint member 6 from the opposite side of the rotary pile 1. Even in such a joint structure, by providing a joint protection structure including a strip member 3 and a plurality of ribs 4 adjacent to the joint structure in the rotary pile 1, the resistance received by the sleeve pipe 7 protruding outward from the outer peripheral surface of the rotary pile 1 during penetration can be reduced, improving workability and suppressing wear of the joint structure.

[0020] (Fourth embodiment) 7 is a diagram showing a connecting portion of a rotary pile provided with a joint protection structure according to a fourth embodiment of the present invention. In this embodiment, the mechanical joint structure includes a sleeve pipe 17 that is placed over the end of the rotary pile 1 and previously joined to the rotary pile 1 by welding or the like. The sleeve pipe 17 is formed with bolt holes 16A and 16B in intersecting directions. Another rotary pile 9 is inserted from the opposite side of the sleeve pipe 17, the bolt holes 18A and 18B formed in the rotary pile 9 are overlapped with the bolt holes 16A and 16B of the sleeve pipe 17, a bolt 20A is inserted into the bolt holes 16A and 18A and the opposite side is fixed with a nut, and a bolt 20B is inserted into the bolt holes 16B and 18B and the opposite side is fixed with a nut 21B, whereby the rotary pile 1 and another rotary pile 9 are connected to each other. Even with such a joint structure, by providing a joint protection structure including a band-shaped member 3 and multiple ribs 4 adjacent to the joint structure on the rotary pile 1, it is possible to reduce the resistance that components such as the sleeve pipe 17, bolts 20A, 20B and nuts 21B that protrude outward from the outer surface of the rotary pile 1 experience when they are penetrated, thereby improving workability and suppressing wear on the joint structure.

[0021] In the above third and fourth embodiments, examples are shown in which the joint protection structure includes a band-shaped member 3 and a plurality of ribs 4, but in these examples, an intermediate flange 5 may be arranged as in the second embodiment, and the ends of the ribs 4 may be joined to the intermediate flange 5.

[0022] Fifth embodiment FIG. 8 is a view showing a connecting portion of a rotary pile provided with a joint protection structure according to a fifth embodiment of the present invention, and FIG. 9 is a view taken along line IX-IX in FIG. 8. In FIG. 8 and FIG. 9, end plates 2, 12, a bolt 23, and nuts 24, 25 are shown as a mechanical joint structure between a rotary pile 1 and another rotary pile 11. The end plate 2 is configured in the same manner as in the first embodiment, and an engagement hole 21 is formed in a portion corresponding to the inside of the rotary pile 1. A similar engagement hole (not shown) is also formed in the end plate 12 on the rotary pile 11 side, and the same engagement member (not shown) is engaged with these engagement holes. A bolt 23 is inserted into a bolt hole formed in a flange-shaped portion of the end plates 2, 12, and is fastened using nuts 24, 25. The nuts 24, 25 form a double nut for preventing loosening. The end plates 2, 12 are joined together by fastening the bolt 23 and the nuts 24, 25, and the state in which the engagement member is engaged with the engagement hole is maintained.

[0023] The joint protection structure in this embodiment includes ribs 4 arranged in the circumferential direction of the rotary pile 1. The ribs 4 protrude from the outer circumferential surface of the rotary pile 1 radially outward, and the end of the rib 4 on the end plate 2 side is joined to the end plate 2. In this embodiment, as in the first embodiment, the ribs 4 function as an excavation bit that excavates the ground near the outer circumferential surface of the rotary pile 1 prior to the mechanical joint structure including the end plate 2 when the rotary pile 1 penetrates the ground while rotating. Therefore, the resistance received by the flange-like portions of the end plates 2, 12 protruding outward from the outer circumferential surface of the rotary pile 1 and the bolts 23 inserted into the bolt holes formed in the flange-like portions can be reduced, improving workability and suppressing wear of the joint structure.

[0024] In the above fifth embodiment, the rib 4 protrudes from the outer circumferential surface of the rotary pile 1, but the band-shaped member 3 may be disposed as in the above second embodiment, and the rib 4 may protrude from the band-shaped member 3 to the radially outer side of the rotary pile 1. In the illustrated example, a rib 14 similar to the rib 4 on the end plate 2 side is also disposed on the end plate 12 side. In other embodiments, by providing a joint protection structure on both sides of the mechanical joint structure in this manner, for example, the shape of the members of the rotary pile may be made common on both ends, or the resistance of the mechanical joint structure during reverse rotation may be reduced.

[0025] Although the preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings, the present invention is not limited to these examples. It is clear that a person skilled in the art in the technical field to which the present invention pertains can come up with various modified or altered examples within the scope of the technical ideas described in the claims, and it is understood that these also naturally fall within the technical scope of the present invention. [Explanation of symbols]

[0026] 1...rotating pile, 2...end plate, 21...engagement hole, 22...bolt hole, 23...bolt, 24, 25...nut, 3...belt-shaped member, 4, 14...rib, 5...intermediate flange, 6...connecting member, 7...sleeve tube, 8...connecting member, 9...rotating pile, 11...rotating pile, 12...end plate, 16A...bolt hole, 16B...bolt hole, 17...sleeve tube, 18A, 18B...bolt holes, 20A, 20B...bolt, 21B...nut.

Claims

1. A joint protection structure provided adjacent to a mechanical joint structure of a rotary pile, The mechanical joint structure is formed at an end of the rotary pile and has a portion protruding outward from an outer circumferential surface of the rotary pile, The joint protection structure includes a band-shaped member joined to the outer peripheral surface of the rotary pile at a position adjacent to the mechanical joint structure, and a plurality of ribs protruding radially outward from the rotary pile and arranged in the circumferential direction of the rotary pile; The plurality of ribs form a joint protection structure for a rotary pile protruding from the outer peripheral surface of the band-shaped member.

2. The joint protection structure for a rotary pile according to claim 1 , wherein the ends of the plurality of ribs opposite the mechanical joint structure have a tapered shape.

3. The mechanical joint structure includes: An end plate is joined to an end of the rotary pile, and an outer periphery of the end plate forms a flange-like portion that protrudes outward from the outer periphery of the rotary pile; An engagement member that is engaged with an engagement hole formed in a portion of the end plate that corresponds to the inside of the rotary pile; Bolts are inserted into a plurality of bolt holes formed in the flange-like portion, respectively; The joint protection structure for a rotary pile according to claim 1 or 2, comprising:

4. The engagement hole is polygonal when viewed in cross section of the rotary pile, The joint protection structure for a rotary pile according to claim 3 , wherein at least a portion of the plurality of ribs are arranged at positions that do not overlap with corners of the polygon in the circumferential direction of the rotary pile.

5. The joint protection structure for a rotary pile according to claim 1 or 2, wherein the mechanical joint structure includes a sleeve pipe that is placed over an end of the rotary pile or a joint member that is joined to the end of the rotary pile.

6. The joint protection structure for a rotary pile according to claim 1 , wherein the plurality of ribs are arranged apart from the mechanical joint structure.

7. The joint protection structure further includes an intermediate flange joined to an outer circumferential surface of the rotary pile, The joint protection structure for a rotary pile according to claim 6 , wherein ends of the plurality of ribs on the side of the mechanical joint structure are joined to the intermediate flange.

8. The joint protection structure for a rotary pile according to claim 3 or 4, wherein ends of the plurality of ribs on the side of the mechanical joint structure are joined to the end plate.

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