Steel pipe pile structure and stop plate for steel pipe pile structure

Abstract

To easily install a stop plate for concrete filling in a steel pipe pile, improve construction efficiency, and reduce cost required for construction.SOLUTION: A steel pipe pile structure includes a steel pipe pile 2 having a tapered part 20 having a diameter reduced toward a lower end side from an upper end side, a disk-like stop plate 3 which is installed inside the tapered part 20, and has an outer diameter smaller than an upper end diameter of the tapered part 20 and larger than a lower end diameter thereof, and concrete 4 which is made to fill the upper side of the stop plate 3 in the steel pipe pile 2.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a steel pipe pile structure and a retaining plate for a steel pipe pile structure. [Background technology]

[0002] Conventionally, steel pipe piles are subjected to vertical loads (axial force) and horizontal loads due to earthquakes, wind, etc., and bending moments are generated by these horizontal loads. Therefore, when designing steel pipe piles, it is necessary to consider the vertical and horizontal bearing capacity. In particular, for horizontal loads, it is common to adopt methods such as increasing the pile diameter or thickening the plate thickness to deal with the large bending moment generated at the top of the pile.

[0003] In response to this, a CFT structure (concrete filled steel tube structure) is known as a technique for efficiently reinforcing the pile head, in which the pile head is filled with concrete to increase rigidity, as shown in Patent Documents 1 and 2, for example. The steel pipe pile with a CFT structure shown in Patent Document 1 describes providing a retaining plate for holding back concrete at the lowest position of the section to be filled with concrete.

[0004] Patent Document 2 describes another retaining plate structure in which a plate member is suspended via a steel bar that is fixed to and suspended from the head of the pile. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2007-297865 A [Patent Document 2] Japanese Patent Application Publication No. 10-311045 Summary of the Invention [Problem to be solved by the invention]

[0006] In the case of a steel pipe pile with a CFT structure as shown in the above-mentioned Patent Document 1, in order to install a retaining plate at a predetermined height, a manufacturing process is required in which a retaining claw or a steel ring for supporting the retaining plate from below is welded inside the steel pipe. In this case, there is a problem that the manufacturing process and costs increase because the inside of the steel pipe is processed, and there is room for improvement in this respect.

[0007] Furthermore, in the case of the above-mentioned Patent Document 2, there were problems such as the need to combine multiple steel materials as components and the time and effort required for installing the fixing brackets.

[0008] The present invention has been made in consideration of the above-mentioned problems, and has an object to provide a steel pipe pile structure and a retaining plate for a steel pipe pile structure that allows a retaining plate for filling concrete to be easily installed inside a steel pipe pile, improves construction efficiency, and reduces construction costs. [Means for solving the problem]

[0009] In order to achieve the above-mentioned object, the steel pipe pile structure of the present invention is characterized by comprising a steel pipe pile having a tapered portion that narrows in diameter from the upper end to the lower end, a disk-shaped retaining plate installed inside the tapered portion and having an outer diameter smaller than the upper end diameter of the tapered portion and larger than the lower end diameter, and concrete filled above the retaining plate within the steel pipe pile.

[0010] According to the present invention, by providing a tapered portion at a position that matches the pouring height of the concrete, a disk-shaped retaining plate with an outer diameter smaller than the upper end diameter of the tapered portion and larger than the lower end diameter can be easily installed on the tapered portion. This makes it possible to provide a retaining plate that functions as a bottom cover for the concrete filled in the steel pipe pile, and eliminates the need for welding members such as steel pipe rings to fix the retaining plate at a predetermined height inside the steel pipe pile, as in the conventional method, thereby reducing the manufacturing process and costs. Furthermore, in the present invention, even if the pile driving depth deviates from the initial plan, the installation level of the retaining plate can be adjusted on-site by changing the diameter of the retaining plate.

[0011] In the steel pipe pile structure according to the present invention, it is preferable that the upper end of the tapered portion is located at a distance of 6D or less from the head of the steel pipe pile, where D is the head diameter of the steel pipe pile.

[0012] In this case, the tapered portion is located at a distance of 6D or less from the head of the steel pipe pile, where D is the pile head diameter of the steel pipe pile. Therefore, the tapered portion, where the cross section of the steel pipe pile becomes smaller, can be placed at a position where the bending moment acting on the steel pipe pile converges.

[0013] In the steel pipe pile structure of the present invention, a tapered surface is formed on the outer peripheral edge of the retaining plate, the diameter of which narrows from the upper end to the lower end, and it is preferable that the steel pipe pile side taper angle α of the tapered portion of the steel pipe pile and the retaining plate side taper angle β of the tapered surface of the retaining plate satisfy equation (1).

[0014]

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[0015] In this case, the retaining plate can be positioned with the upper surface of its outer edge in contact with the inner surface of the pipe in the tapered section, allowing the retaining plate to be positioned in a stable posture, thereby improving the filling ability of the concrete.

[0016] In addition, in the steel pipe pile structure of the present invention, the retaining plate may be characterized in that a guide member is provided which protrudes downward and is supported in a state where it is inserted into the steel pipe below the tapered portion of the steel pipe pile.

[0017] With this configuration, the guide member is fitted into the steel pipe below the tapered portion, so the position of the stop plate can be stabilized, and when the stop plate is installed, it can be placed in a stable position, and when concrete is filled into the steel pipe, the stop plate can be prevented from shifting and causing concrete to leak out downwards. This makes it possible to further improve construction efficiency and reduce construction costs.

[0018] Furthermore, in the steel pipe pile structure of the present invention, the guide member, at the portion inserted into the lower steel pipe, may be characterized in that when the distance L from the lower end of the tapered portion of the steel pipe pile to the lower end of the guide member at the time when the retaining plate is installed is equal to the distance (2), and when the lower end diameter of the tapered portion of the steel pipe pile is D', in a horizontal cross section of the lower steel pipe, at least a part of the guide member is located in the area between the imaginary circles of 0.8D' and 0.9D', and the outer end of the guide member is not located outside the imaginary circle of 0.9D'.

[0019]

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[0020] With this configuration, the guide member is stably fitted into the steel pipe below the tapered portion, thereby stabilizing the posture of the retaining plate, thereby increasing the posture stability when the retaining plate is installed and preventing the retaining plate from rotating when pouring concrete.

[0021] In the steel pipe pile structure according to the present invention, the guide member may be located within a range of the distance L that satisfies formula (3).

[0022]

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[0023] In this case, the position of the retaining plate can be more stabilized, the positional stability when the retaining plate is installed can be increased, and the rotation of the retaining plate when pouring concrete can be suppressed to, for example, less than approximately 6°.

[0024] Furthermore, a retaining plate for a steel pipe pile structure according to the present invention is characterized in that it is used in the above-mentioned steel pipe pile structure. Effect of the Invention

[0025] According to the steel pipe pile structure and retaining plate for a steel pipe pile structure of the present invention, the retaining plate for filling with concrete can be easily installed inside the steel pipe pile, thereby improving construction efficiency and reducing construction costs. [Brief description of the drawings]

[0026] [Figure 1] FIG. 1 is a vertical cross-sectional view showing a steel pipe pile structure according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is an enlarged longitudinal sectional view of a main part of the steel pipe pile structure shown in FIG. [Diagram 3] FIG. [Figure 4] FIG. [Diagram 5] FIG. 11 is a side view showing an example of a retaining plate having another shape. [Figure 6] FIG. 13 illustrates bending moments at depth. [Figure 7] FIG. 13 is a diagram showing the relationship between depth and bending moment for each N value. [Figure 8] 1(a) to 1(c) are diagrams illustrating a construction method for a steel pipe pile structure. [Figure 9] FIG. 11 is a vertical cross-sectional view showing a steel pipe pile structure according to a second embodiment. [Figure 10] FIG. 11 is an enlarged longitudinal sectional view of a main part of the steel pipe pile structure according to the second embodiment. [Figure 11] FIG. 11 is a side view showing the configuration of a retaining plate according to the second embodiment. [Figure 12] FIG. 11 is a horizontal sectional view showing the configuration of a retaining plate according to the second embodiment. [Figure 13] 13(a) and 13(b) are diagrams for explaining the rotation angle of the retaining plate. [Figure 14] FIG. 11 is a side view showing another embodiment of the guide member. [Figure 15] FIG. 11 is a side view showing another embodiment of the guide member. [Figure 16] FIG. 11 is a side view showing another embodiment of the guide member. [Figure 17] FIG. 11 is a side view showing another embodiment of the guide member. [Figure 18] FIG. 11 is an enlarged longitudinal sectional view of a main part of the steel pipe pile structure according to the third embodiment. [Figure 19] FIG. 11 is a perspective view showing a retaining plate structure according to a first modified example. [Figure 20] FIG. 11 is a horizontal sectional view showing a retaining plate structure according to a first modified example. [Figure 21] FIG. 11 is a perspective view showing a retaining plate structure according to a second modified example. [Figure 22] FIG. 13 is a perspective view showing a retaining plate structure according to a third modified example. [Diagram 23] FIG. 13 is a horizontal sectional view showing a retaining plate structure according to a third modified example. [Figure 24] 13A is a horizontal cross-sectional view of the retaining plate structure according to the fourth modified example, as viewed from below, and FIG. 13B is a retaining plate structure for comparison. [Diagram 25] 13(a) and 13(b) are horizontal cross-sectional views of a retaining plate structure according to a fifth modified example, viewed from below. [Figure 26] 13(a) and 13(b) are horizontal cross-sectional views of a retaining plate structure according to a sixth modified example, viewed from below. [Figure 27] 13(a) and 13(b) are horizontal cross-sectional views of a retaining plate structure according to a seventh modified example, viewed from below. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0027] Hereinafter, a steel pipe pile structure and a retaining plate for a steel pipe pile structure according to an embodiment of the present invention will be described with reference to the drawings.

[0028] (First embodiment) In the steel pipe pile structure 1 of this embodiment shown in Figures 1 and 2, a steel pipe pile 2 is installed with its pipe axis O facing up and down and filled with concrete 4, and a cover member (a retaining plate 3 described later) is provided in the middle of the pipe body of the steel pipe pile 2 in the up and down direction to hold back the concrete 4.

[0029] The steel pipe pile structure 1 comprises a steel pipe pile 2 having a tapered section 20 that reduces in diameter from the upper end side to the lower end side, a disk-shaped retaining plate 3 that is installed on an inner pipe surface 20c of the tapered section 20 and has an outer diameter smaller than an upper end diameter D1 and larger than a lower end diameter D2 of the tapered section 20, and concrete 4 that is filled above the retaining plate 3 within the steel pipe pile 2. Note that, in the case where a tapered surface is formed on the outer periphery of the retaining plate 3 as described later, the diameter of the upper surface 3a of the retaining plate 3 is taken as the outer diameter of the retaining plate 3.

[0030] The steel pipe pile 2 has, in order from the top, a large diameter section 21, a tapered section 20, and a small diameter section 22. The tapered section 20 is tapered from the lower end of the large diameter section 21 (upper end 20a of the tapered section 20) to the upper end of the small diameter section 22 (lower end 20b of the tapered section 20). The large diameter section 21 is a steel pipe above the tapered section 20. The inner diameter of the large diameter section 21 is equal to the inner diameter (upper end diameter D1) of the upper end 20a of the tapered section 20. The small diameter section 22 is a steel pipe below the tapered section 20. The inner diameter of the small diameter section 22 is equal to the inner diameter (lower end diameter D2) of the lower end 20b of the tapered section 20. The plate thickness of the steel pipe pile 2 is constant over the entire length. That is, the plate thicknesses of the large diameter section 21, the tapered section 20, and the small diameter section 22 are constant.

[0031] The height position of the upper end 20a of the tapered portion 20 of the steel pipe pile 2 (the distance from the pile head 2A (upper end of the pile) of the steel pipe pile 2) is set to be within 6D or less of the pile head diameter D of the steel pipe pile 2.

[0032] As shown in Fig. 1 and Fig. 2, the retaining plate 3 is disposed in the vertical middle of the tapered portion 20. The retaining plate 3 has a holding force for holding down the concrete 4 filled in the pipe from below while in contact with the pipe inner surface 20c of the tapered portion 20. The retaining plate 3 is formed in a plate shape made of a steel plate or a plastic plate. Note that, as long as the retaining plate 3 can ensure stability when installed and the holding force for holding down the concrete from below, its material and shape, such as hollow or solid, flat or curved / uneven, are not important.

[0033] As shown in Figures 3 and 4, an inclined surface (tapered surface 3c) that gradually narrows in diameter from the upper surface 3a to the lower surface 3b is formed on the outer periphery of the retaining plate 3. The steel pipe pile-side taper angle α (see Figure 2) of the tapered portion 20 of the steel pipe pile 2 and the retaining plate-side taper angle β (see Figures 3 and 4) of the tapered surface 3c of the retaining plate 3 are set to satisfy formula (1).

[0034]

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[0035] The retaining plate 3A shown in Fig. 5 may have an outer peripheral edge 3d that does not have a tapered surface. In this case, the outer diameters of the upper surface 3a and the lower surface 3b of the retaining plate 3A are constant. The outer diameter of the retaining plate 3A is set to be smaller than the inner diameter of the large diameter portion 21 (upper end diameter D1 of the tapered portion 20) shown in Fig. 2 and larger than the inner diameter of the small diameter portion 22 (lower end diameter D2 of the tapered portion 20).

[0036] In constructing the steel pipe pile structure 1 in this manner, as shown in Figure 2, the steel pipe pile 2 has a tapered section 20 that gradually narrows downward from a large diameter section 21 near the pile head, and a disk-shaped retaining plate 3 that is smaller than the inner diameter of the large diameter section 21 (upper end diameter D1 of the tapered section 20) and larger than the inner diameter of the small diameter section 22 (lower end diameter D2 of the tapered section 20) is installed on the pipe inner surface 20c of the tapered section 20, thereby providing a cover member to receive the concrete 4 to be filled.

[0037] Here, the position in the height direction where the tapered portion 20 is provided and the tapered shape of the tapered portion 20 will be specifically described. It is generally known that the bending moment when a horizontal force acts on the pile head 2A converges to a small value at a depth of 6D or more from the pile head 2A relative to the pile head diameter D, as shown in Fig. 1. Therefore, by positioning the upper end 20a of the tapered portion 20 within a range of 6D from the pile head 2A, it is possible to fill the pile with concrete 4 at low cost.

[0038] The two-dot chain line M shown in FIG. As shown in Fig. 1, the specific position (height) of the tapered portion 20 is preferably such that the portion Ma of the pile head 2A where the bending moment M changes suddenly is located above the upper end of the tapered portion 20. In other words, the tapered portion 20 is set so as to be located at a position where the bending moment M has converged to a certain extent.

[0039] Figure 6 shows a comparison of bending moment distribution for a straight pile (solid line M1) and a tapered pile with a tapered section (dotted line M2) in ground G with an N-value of 5. The straight pile has a diameter of 300 mm and a steel pipe thickness of 6 mm. The tapered pile has a pile head diameter of 300 mm, a lower pile diameter of 200 mm, a steel pipe thickness of 6 mm, and a tapered shape 1 m to 1.5 m from the pile head. The magnitude of the bending moment M (kN m) in the pile head area (depth of approximately 0 m to 1 m) is similar for the straight pile (M1) and tapered pile (M2). The bending moment M2 of the tapered pile is smaller than the bending moment M1 of the straight pile because the lower pile diameter (inner diameter of the small diameter part) below the tapered section is smaller.

[0040] Moreover, Figure 7 shows a comparison of the distribution of bending moments in three types of ground with different N values ​​(N values ​​= 2.5, 5, 10) for tapered piles. The symbols M3, M4, and M5 indicate the bending moments at N values ​​of 2.5, 5, and 10, respectively. The vertical axis shows the bending moment, its absolute value as a ratio to the pile head moment, and the horizontal axis is expressed as y / D using the depth (distance y) and pile head diameter D. It can be seen that the bending moment M monotonically decreases and then increases slightly with respect to the pile head diameter D at depths of 4D to 7D, but converges to a certain value or less at depths of 3D to 5D.

[0041] In addition, the rate of reduction in the section modulus due to diameter reduction is about 0.24 times even when the inner diameter of the small diameter part is half the pile head diameter D, but it can be confirmed that the bending moment M at depths of 3D to 5D in each area is kept to less than 0.2 times the moment generated at the pile head 2A. For these reasons, in practice, it is preferable that the upper end position of the tapered portion 20 of the steel pipe pile 2 be located 3D to 5D from the pile head portion 2A.

[0042] Next, a construction procedure for the steel pipe pile structure 1 using the above-mentioned retaining plate 3 will be specifically described with reference to the drawings such as FIG. As shown in Fig. 8(a), first, the steel pipe pile 2 is driven into the ground G by pressing it (rotary pressing it in the case of a wing pile). The method of driving the steel pipe pile 2 can be, for example, the central trenching method, the pre-boring method, the hammering method, the rotary pressing method, or the like.

[0043] Next, as shown in Figure 8(b), the retaining plate 3 is lowered into the steel pipe pile 2 using a wire 5 such as a wire cable, and the retaining plate 3 is installed on the inner pipe surface 20c of the tapered portion 20 of the steel pipe pile 2 (see Figure 8(c)). At this time, the retaining plate 3 is dropped in a suspended state from above the steel pipe pile 2 onto the pipe inner surface 20c of the tapered portion 20. The position at which the retaining plate 3 is dropped is determined so that the lower end surface 4a of the concrete 4 filled in the steel pipe pile 2 becomes the upper surface 3a of the retaining plate 3, as shown in Figures 2 and 8(c). If bentonite liquid has accumulated inside the driven steel pipe pile 2 before the installation of the retaining plate 3, a weight may be attached to the retaining plate 3 to sink it into the bentonite liquid. Also, the retaining plate 3 may be installed after draining the bentonite liquid accumulated inside the steel pipe pile 2 before the installation of the retaining plate 3.

[0044] Next, as shown in Fig. 8(c), the tapered surface 3c of the retaining plate 3 is brought into contact with the pipe inner surface 20c of the tapered portion 20. This allows the frictional force and binding force between the pipe inner surface 20c and the tapered surface 3c of the retaining plate 3 to be fully exerted, and the retaining plate 3 can form a bottom cover that blocks the concrete 4 to be poured later from below. Thereafter, the bentonite liquid in the steel pipe pile 2 (not shown) is sucked up and discharged using a vacuum, a concrete pipe is inserted into the steel pipe pile 2, and concrete is poured.

[0045] Thereafter, as shown in Fig. 8(c), concrete 4 is poured and filled into the pile head 2A of the steel pipe pile 2. Pouring the concrete 4 completes the construction of the tubular structure in which the steel pipe pile 2 is filled with the concrete 4. This allows the steel pipe pile 2 filled with the concrete 4 to have improved strength as a tubular structure.

[0046] Next, the function of the above-mentioned steel pipe pile structure 1 and the retaining plate 3 for a steel pipe pile structure will be described in detail with reference to the drawings. As shown in Fig. 2, according to this embodiment, by providing the tapered portion 20 of the steel pipe pile 2 at a position corresponding to the pouring height of the concrete 4, it is possible to easily install a disk-shaped retaining plate 3 having an outer diameter smaller than the upper end diameter D1 and larger than the lower end diameter D2 of the tapered portion 20 in the tapered portion 20. Therefore, it is possible to provide the retaining plate 3 that functions as a bottom cover for the concrete 4 filled in the steel pipe pile 2, and since it is not necessary to weld members such as steel pipe rings for fixing the retaining plate at a predetermined height inside the steel pipe pile as in the conventional method, it is possible to reduce the manufacturing process and costs. In addition, in this embodiment, even if the pile driving depth deviates from the initial plan, the installation level of the retaining plate 3 can be adjusted on-site by changing the diameter of the retaining plate.

[0047] In this embodiment, the tapered portion 20 is positioned at a distance of 6D or less from the pile head 2A of the steel pipe pile 2 with respect to the pile head diameter D of the steel pipe pile 2. Therefore, the tapered portion 20 where the cross section of the steel pipe pile 2 becomes smaller can be disposed at a position where the bending moment acting on the steel pipe pile 2 converges.

[0048] In this embodiment, the steel pipe pile side taper angle α of the tapered portion 20 of the steel pipe pile 2 and the retaining plate side taper angle β of the tapered surface 3c of the retaining plate 3 satisfy the above formula (1), so the retaining plate 3 can be placed with the upper surface side of the outer periphery of the retaining plate 3 in contact with the pipe inner surface of the tapered portion 20. Therefore, the retaining plate 3 can be placed in a stable posture, and the filling property of the concrete 4 can be improved.

[0049] In the steel pipe pile structure 1 and the retaining plate 3 for the steel pipe pile structure according to the present embodiment described above, by providing the steel pipe pile 2 with a tapered portion 20, the retaining plate 3 for filling with concrete 4 can be easily installed, thereby improving construction efficiency and reducing construction costs.

[0050] Second embodiment As shown in Figures 9 and 10, in the steel pipe pile structure 1A according to the second embodiment, a cylindrical guide member 31 is provided on the retaining plate 3, which protrudes downward from the lower surface 3b of the retaining plate 3 and is supported in a state inserted inside the steel pipe pile 2 (see Figure 11).

[0051] The retaining plate 3 is installed by suspending it using a wire 5 (see FIG. 8(b)) after the steel pipe pile 2 is driven in. At that time, a guide member 31 that serves as a guide is attached to the underside 3b of the retaining plate 3 in order to prevent the retaining plate 3 from rotating and to ensure stability. As with the retaining plate 3, the guide member 31 may be of any material or have any shape, such as hollow or solid, as long as it can ensure stability when the retaining plate 3 is installed.

[0052] In the portion of the guide member 31 inserted into the small diameter portion 22 (lower steel pipe), the distance L from the lower end 20b of the tapered portion 20 of the steel pipe pile 2 to the lower end 31a of the guide member 31 when the retaining plate 3 is installed satisfies equation (2). Furthermore, when the lower end diameter of the tapered portion 20 of the steel pipe pile 2 is D2 (hereinafter, "D'" is used), as shown in Fig. 12, in the horizontal cross section of the small diameter portion 22, at least a part of the guide member 31 is present in an area H between the inner virtual circle K1 of 0.8D' and the outer virtual circle K2 of 0.9D', and the outer end portion 31b of the guide member 31 is set so as not to be located outside the outer virtual circle K2 of 0.9D'. Furthermore, it is more preferable to set the guide member 31 so as to be located within the range of distance L that satisfies formula (3). Here, the outer end portion 31b of the guide member 31 is defined as a portion of the guide member 31 located farthest from the central axis of the retaining plate 3 in a plan view seen from the tube axis O direction.

[0053]

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[0054]

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[0055] Thus, in this embodiment, the outer end of the guide member has at least one, preferably two or more, and more preferably three or more in the region H between the inner virtual circle K1 of 0.8D' and the outer virtual circle K2 of 0.9D'.

[0056] 12, a part (outer peripheral side part) of the cylindrical guide member 31 is present in the region H. In the present embodiment, the guide member 31 is cylindrical with the central axis C1 of the retaining plate 3 as its cylindrical axis, and the central axis of the guide member 31 coincides with the tube axis O, so that the guide member 31 is evenly disposed in the region H without being deviated from the center over the entire circumference. In this way, when the central axis of the guide member 31 coincides with the central axis C1 of the retaining plate 3, the relationship between the distance d from the central axis C1 of the guide member 31 to the outer end portion 31b of the guide member 31 and the inner diameter D' of the small diameter portion 22 can be expressed by equation (4).

[0057]

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[0058] That is, when a cylindrical guide member 31 is used as in the second embodiment, it is possible to suppress the rotation angle θ of the retaining plate 3 (see FIGS. 13(a) and 13(b)) to approximately 6°.

[0059] Here, the reason why the rotation angle θ of the retaining plate 3 is less than 6° will be described. Fig. 13(a) shows a cross-sectional view of the retaining plate 3 when it is installed with the plate surface perpendicular to the pipe axis O of the steel pipe pile 2. The rotation angle θ at this time is 0°. The distance indicated by the symbol L' in Fig. 13(a) indicates the distance extending in the direction of the central axis C1 of the guide member 31, but as will be described later, in calculating the maximum value of the rotation angle θ below, this is the same as the distance L from the lower end 20b of the tapered portion 20 to the lower end 31a of the guide member 31 (L' = L).

[0060] As shown in FIG. 13( b ), a cross-sectional view of the retaining plate 3 rotated about a horizontal axis passing through the pipe axis O of the steel pipe pile 2 is shown. In this case, rotation stops when the guide member 31 comes into contact with the inner surface 22a of the small diameter portion 22, so the distance x between the guide member 31 and the inner surface 22a rotates by (D'-2d) / 2. From the triangle surrounded by the three vertices A, B, and C shown in Figure 13(b), the rotation angle θ can be calculated by tan θ = side BC / side AB. Here, since AB = L' and BC ≦ (D'-2d) / 2, tan θ is given by the following formula (5). In this case, if L≧D' and 2d≧0.8D', the rotation angle θ is maximum when 2d=0.8D', the upper end of the guide member 31 is positioned at the position (depth) of the lower end 20b of the tapered portion 20 of the steel pipe pile (L'=L), and the distance from the lower end 20b of the tapered portion 20 to the lower end of the guide member 31 is D' (L=D'), therefore, from equation (6), the rotation angle θ≦5.8°.

[0061]

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[0062] Next, the configuration of guide member 31 satisfying the above-mentioned formulas (2) and (4) is shown in Figs. 14 and 15, and the configuration of guide member 31 satisfying the formulas (3) and (4) is shown in Figs. 16 and 17. The guide member 31A shown in FIG. 14 has a form in which the distance L is greater than 0. This guide member 31A has a small diameter cylindrical portion 310 at the upper portion and a large diameter cylindrical portion 311 at the lower portion. The small diameter cylindrical portion 310 is disposed in the tapered portion 20 of the steel pipe pile 2. The diameter 2d of the small diameter cylindrical portion 310 may be less than 0.8D'. The diameter 2d of the large diameter cylindrical portion 311 is set so that there is a portion that satisfies the above formula (4) at a position deeper than the lower end 20b of the tapered portion 20.

[0063] The guide member 31B shown in FIG. 15 has a form in which the distance L is greater than 0. In this guide member 31B, the upper and lower portions are large-diameter cylindrical portions 312 and 313 having the same diameter, and the middle portion is a small-diameter cylindrical portion 314. Furthermore, a part of the upper large-diameter cylindrical portion 312 and the lower large-diameter cylindrical portion 313 are located at a position deeper than the lower end 20b of the tapered portion 20, and a part of the lower large-diameter cylindrical portion 313 is in a range of 1D' or more in depth from the lower end 20b of the tapered portion 20 of the steel pipe pile. The small-diameter cylindrical portion 314 is disposed in a range of less than 1D' in the depth direction from the lower end 20b of the tapered portion 20. The diameter 2d of the small-diameter cylindrical portion 314 may be less than 0.8D'. The diameter 2d of the upper large-diameter cylindrical portion 312 and the lower large-diameter cylindrical portion 313 is set so that there is a part that satisfies the above formula (4) at a position deeper than the lower end 20b of the tapered portion 20.

[0064] The guide member 31C shown in FIG. 16 has a shape in which the distance L satisfies the formula (3). The upper and lower portions of this guide member 31C are large-diameter cylindrical portions 315 and 316 with the same diameter, the middle portion is a small-diameter cylindrical portion 317, and a part of the lower large-diameter cylindrical portion 316 is disposed in a range of 1D' or more in the depth direction from the bottom end of the tapered portion. A part of the small-diameter cylindrical portion 317 is disposed in the tapered portion 20, and the other part is disposed in a range of less than 1D' in the depth direction from the bottom end of the tapered portion. The diameter 2d of the small-diameter cylindrical portion 317 may be less than 0.8D'. The diameter 2d of the lower large-diameter cylindrical portion 316 is set so that a part that satisfies the formula (4) exists at a depth of 1D' or more from the bottom end of the tapered portion.

[0065] The guide member 31D shown in FIG. 17 has a shape in which the distance L satisfies the formula (3). The upper part of this guide member 31D is a large-diameter cylindrical portion 318, and the lower part is a reduced-diameter portion 319 whose diameter is reduced downward, and a part of the reduced-diameter portion 319 at the lower part is disposed in a range of 1D' or more in the depth direction from the lower end of the tapered portion. A part of the large-diameter cylindrical portion 318 is disposed in the tapered portion 20, and the other part is disposed in a range of less than 1D' in the depth direction from the lower end of the tapered portion. The diameter 2d of the reduced-diameter portion 319 may be less than 0.8D' in the other part, as long as there is a part that satisfies the formula (4) at a depth of 1D' or more from the lower end of the tapered portion. The diameter 2d of the large-diameter cylindrical portion 318 is set to satisfy the formula (4) at a depth of 1D' or more from the lower end of the tapered portion.

[0066] Furthermore, in this embodiment, the relationship between the distance L from the lower end of the tapered portion 20 of the steel pipe pile 2 to the lower end of the guide member 31 satisfies equations (3) and (4). Therefore, the guide member 31 is stably fitted into the smaller diameter portion 22 from the tapered portion 20. This stabilizes the posture of the retaining plate 3 and improves the filling ability of the concrete 4.

[0067] Furthermore, in this embodiment, the guide member 31 is fitted into the steel pipe below the tapered portion 20, so the position of the retaining plate 3 can be stabilized, and when the retaining plate 3 is installed, the retaining plate 3 can be placed in a stable position, and when the steel pipe is filled with concrete 4, the retaining plate 3 can be prevented from shifting and causing the concrete 4 to leak downward. Therefore, construction efficiency can be improved and construction costs can be reduced.

[0068] Third embodiment Next, the retaining plate 3 of the second embodiment shown in Fig. 2 described above is not limited in material or thickness as long as it has the strength to withstand the weight of the concrete 4 and the filling property of the concrete 4. The retaining plate 3B of the third embodiment shown in Fig. 18 is thicker than the retaining plate 3 of the first embodiment described above.

[0069] In the third embodiment, by increasing the thickness of the retaining plate 3B, the contact area with the pipe inner surface 20c of the tapered portion 20 of the steel pipe pile 2 can be increased, and adhesion can be improved. This makes it possible to more reliably prevent the concrete 4 filled from above from flowing out below the retaining plate 3B.

[0070] (First Modification) Next, a first retaining plate structure 30A according to a first modified example shown in FIG. 19 has a configuration in which a rectangular prism-shaped guide member 32 having a rectangular cross-section when viewed from above and below is provided below the non-tapered retaining plate 3A of the second embodiment described above. In the first retaining plate structure 30A, the guide member 32 is inserted into the small diameter portion 22 (see Figure 2) of the steel pipe pile 2, and the four corners 32a (outer ends) of the guide member 32 are positioned in close proximity to the inner surface of the small diameter portion 22.

[0071] In the case of the first modified example, as shown in FIG. 20, in order for the guide member 32 to exhibit its stability, there are at least three positions (four positions in the first modified example) through which the corner portion 32a of the guide member 32 passes within a range of 0.8 to 0.9 times the inner diameter of the small diameter portion 22 in a horizontal cross-sectional view (region H between the inner virtual circle K1 and the outer virtual circle K2).

[0072] (Second Modification) Next, a second retaining plate structure 30B according to a second modified example shown in Fig. 21 is configured to include a guide member 33 having a plurality of long members 33A such as steel bars, long bolts, reinforcing bars, etc., extending downward from the lower surface 3b of the non-tapered retaining plate 3A of the second embodiment described above. In the second retaining plate structure 30B, the long members 33A of the guide member 33 are inserted into the small diameter portion 22 (see Fig. 2) of the steel pipe pile 2, and the four long members 33A are arranged in close proximity to the inner surface of the small diameter portion 22.

[0073] In the case of the second modified example, in order for the guide member 33 to exhibit its stability, there are at least three or more positions (four in the second modified example) through which the multiple elongated members 33A of the guide member 33 pass within a range of 0.8 to 0.9 times the inner diameter of the small diameter portion (see Figure 2) (the area indicated by the symbol H surrounded by dotted lines in Figures 24(a) and (b) described below).

[0074] (Third Modification) Next, a third retaining plate structure 30C according to a third modified example shown in Fig. 22 has a configuration in which a guide member 34 made of an H-shaped steel is provided on the underside 3b of the non-tapered retaining plate 3A of the second embodiment described above. The material axis direction of the guide member 34 is perpendicular to the underside 3b of the retaining plate 3A. In the third retaining plate structure 30C, the guide member 34 is inserted into the small diameter portion 22 (see Fig. 2) of the steel pipe pile 2, and four corners 34a (outer ends) of the guide member 34 are arranged in close proximity to the inner surface of the small diameter portion 22.

[0075] In the case of the third modified example, as shown in FIG. 23, in order for the guide member 34 to exhibit its stability, there are at least three or more positions (four positions in the third modified example) through which the corner portion 34a of the guide member 34 passes within a range (region H between the inner virtual circle K1 and the outer virtual circle K2) of 0.8 to 0.9 times the inner diameter of the small diameter portion (see FIG. 2).

[0076] (Fourth Modification) Next, a fourth retaining plate structure 30D according to a fourth modified example shown in Fig. 24(a) has a configuration in which a guide member 35 shaped like a triangular prism having a triangular cross section in a top-bottom plan view is provided below the non-tapered retaining plate 3A of the second embodiment described above. In the fourth retaining plate structure 30D, the guide member 35 is inserted into the small diameter portion 22 (see Fig. 2) of the steel pipe pile 2, and three corners 35a (outer ends) of the guide member 35 are arranged in close proximity to the inner surface of the small diameter portion 22.

[0077] In the case of the fourth modified example, in order for the guide member 35 to exhibit its stability, there are at least three positions (three positions in the fourth modified example) through which the corner portion 35a of the guide member 35 passes within the region H that is 0.8 to 0.9 times the inner diameter of the small diameter portion 22 (see FIG. 2). In the case of a plate-shaped guide member 36 having an I-shaped cross section in a plan view viewed from the top and bottom below a non-tapered retaining plate 3A as shown in Figure 24(b), there are two positions where the end portion 36a of the guide member 36 passes through in the region H that is 0.8 to 0.9 times the inner diameter of the small diameter portion 22 (see Figure 2), making it difficult to obtain stability as a guide.

[0078] Next, a fifth modified example shown in FIGS. 25(a) and (b) has a configuration in which the ends of the guide members 41, 42 are not disposed at equal distances from the central axis (pipe axis O) of the retaining plate. 25(a) has an isosceles triangular cross section, and each of the three apexes 41a, 41b, and 41c is present in an area H between an inner imaginary circle K1 of 0.8D' and an outer imaginary circle K2 of 0.9D'. In this case, only the single apex 41a is the outer end portion farthest from the tube axis O when viewed from the tube axis direction.

[0079] 25(b) has an equilateral triangular cross section, and each of the three vertices 42a, 42b, and 42c is present in an area H between an inner imaginary circle K1 of 0.8D' and an outer imaginary circle K2 of 0.9D'. In this case, the two vertices 42b and 42c are the outer ends farthest from the tube axis O when viewed from the tube axis direction.

[0080] Next, a sixth modified example shown in FIGS. 26(a) and 26(b) shows a state in which the central axis C1 (center of gravity) of the guide members 43 and 44 and the tube axis O are misaligned. 26(a) has an equilateral triangular cross section, and each of the three vertices 43a, 43b, and 43c is present in an area H between an inner imaginary circle K1 of 0.8D' and an outer imaginary circle K2 of 0.9D'. In this case, the vertex 43a among the three vertices 43a, 43b, and 43c is the outer end portion farthest from the tube axis O when viewed from the tube axis direction.

[0081] 26(b) has a square cross section, and each of the four vertices 44a, 44b, 44c, and 44d exists in an area H between an inner imaginary circle K1 of 0.8D' and an outer imaginary circle K2 of 0.9D'. In this case, the two vertices 44a and 44b among the four vertices 44a, 44b, 44c, and 44d become the outer end portions farthest from the tube axis O when viewed from the tube axis direction.

[0082] Next, a seventh modified example shown in FIGS. 27(a) and 27(b) has a configuration in which only a portion of the top of the guide members 45, 46 exists in the region H described above. 27(a) has an equilateral triangular cross section, and only one apex 45a of three apexes 45a, 45b, and 45c is present in an area H between an inner imaginary circle K1 of 0.8D' and an outer imaginary circle K2 of 0.9D', and the other two apexes 45b and 45c are present inside the inner imaginary circle K1. In this case, one apex 45a of the three apexes 45a, 45b, and 45c is the outer end portion farthest from the tube axis O when viewed from the tube axis direction. Even if there is only one outer end in this manner, the presence of that one outer end (apex 45a) in region H has the effect of preventing rotation in a specific direction.

[0083] 27(b) has a rectangular cross section, and two of the four vertices 46a, 46b, 46c, and 46d, 46a and 46b, are present in an area H between an inner imaginary circle K1 of 0.8D' and an outer imaginary circle K2 of 0.9D', and the other two vertices 46c and 46d are present inside the inner imaginary circle K1. In this case, the two vertices 46a and 46b are the outer ends farthest from the tube axis O when viewed from the tube axis direction.

[0084] The above describes the embodiments of the steel pipe pile structure and the retaining plate for the steel pipe pile structure according to the present invention. However, the present invention is not limited to the above-described embodiments and can be modified as appropriate without departing from the spirit of the present invention.

[0085] For example, in this embodiment, the upper end 20a of the tapered portion 20 of the steel pipe pile 2 is configured to be located at a distance of 6D or less from the pile head 2A of the steel pipe pile 2 relative to the pile head diameter D of the steel pipe pile 2, but is not limited to this.

[0086] In addition, in this embodiment, a tapered surface 3c that narrows in diameter from the upper end side to the lower end side is formed on the outer peripheral edge of the retaining plate 3, and the steel pipe pile side taper angle α of the tapered portion 20 of the steel pipe pile 2 and the retaining plate side taper angle β of the tapered surface 3c of the retaining plate 3 satisfy the above formula (1), but are not limited to this.

[0087] In addition, the retaining plate 3 is provided with a guide member 31 that protrudes downward and is supported in a state of being inserted inside the steel pipe pile 2, but such a guide member 31 can be omitted. In other words, the structure may be made up of only the disk-shaped retaining plate 3.

[0088] In this embodiment, the guide member 31 is set so as to satisfy the above formula (2), (formula (3)) and (4) in terms of the relationship between the distance d from the center of the retaining plate 3 to the outer end 31b of the guide member 31, the inner diameter D' of the lower end of the tapered portion 20 of the steel pipe pile 2, and the distance L from the lower end of the tapered portion of the steel pipe pile 2 to the lower end 31a of the guide member 31 when the retaining plate is installed, but is not limited to this. Furthermore, in this embodiment, the guide member is set so as to satisfy the above formula (2) and to be located in the region H between the inner virtual circle K1 of 0.8D' and the outer virtual circle K2 of 0.9D' in the horizontal cross section of the small diameter portion 22, and the outer end of the guide member is not located outside the outer virtual circle K2 of 0.9D', but is not limited to this.

[0089] Moreover, the length, number and shape of the retaining plates 3 can be set arbitrarily.

[0090] Furthermore, the plate thickness of the steel pipe pile 2 does not need to be constant over the entire length in the pipe axis O direction, and can be set arbitrarily.

[0091] In addition, the components in the above-described embodiments can be replaced with well-known components as appropriate without departing from the spirit of the present invention. [Explanation of symbols]

[0092] 1 Steel pipe pile structure 2 Steel pipe pile 3, 3A, 3B, Retaining plate 4. Concrete 20 Tapered section 20c tube inner surface 21 Large diameter section 22 Small diameter section 30A~30E Stop plate structure 31 Guide member

Claims

1. A steel pipe pile having a tapered portion whose diameter decreases from the upper end side to the lower end side; a disk-shaped stopper plate disposed inside the tapered portion and having an outer diameter smaller than an upper end diameter of the tapered portion and larger than a lower end diameter of the tapered portion; Concrete filled above the retaining plate in the steel pipe pile; A steel pipe pile structure comprising:

2. The steel pipe pile structure according to claim 1, characterized in that the upper end of the tapered portion is located at a distance of 6D or less from the head of the steel pipe pile, where D is the head diameter of the steel pipe pile.

3. The stop plate has an outer circumferential edge formed with a tapered surface that decreases in diameter from the upper end side to the lower end side, The steel pipe pile structure according to claim 1 or 2, characterized in that the steel pipe pile side taper angle α of the tapered portion of the steel pipe pile and the retaining plate side taper angle β of the tapered surface of the retaining plate satisfy formula (1). [0010]

4. The steel pipe pile structure according to any one of claims 1 to 3, characterized in that the retaining plate is provided with a guide member that protrudes downward and is supported in a state where it is inserted into the steel pipe below the tapered portion of the steel pipe pile.

5. The guide member satisfies formula (2) at the distance L from the lower end of the tapered portion of the steel pipe pile to the lower end of the guide member at the time of installation of the stop plate, in the portion inserted into the lower steel pipe, The steel pipe pile structure described in claim 4, characterized in that when the lower end diameter of the tapered portion of the steel pipe pile is D', in a horizontal cross section of the lower steel pipe, at least a part of the guide member is located in the area between the imaginary circles of 0.8D' and 0.9D', and the outer end of the guide member is not located outside the imaginary circle of 0.9D'. [0025]

6. The steel pipe pile structure according to claim 5, characterized in that the guide member is located within the range of the distance L that satisfies formula (3). [0030]

7. A retaining plate for a steel pipe pile structure, which is used in the steel pipe pile structure according to any one of claims 1 to 6.

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