JP2023076227A - Steel pipe pile structure and stop plate for steel pipe pile structure - Google Patents

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

The present invention relates to steel pipe pile structures and stop plates for steel pipe pile structures.

Conventionally, a vertical load (axial force) and a horizontal load due to an earthquake or wind act on a steel pipe pile, and this horizontal load generates a bending moment. Therefore, it is necessary to consider vertical and horizontal bearing capacity when designing steel pipe piles. In particular, for horizontal loads, it is common to adopt a method of increasing the diameter of the pile or increasing the plate thickness against the large bending moment generated at the top of the pile.

On the other hand, as a technique for efficiently reinforcing the pile head, there is a CFT structure (concrete-filled steel pipe structure) in which the pile head is filled with concrete to increase the rigidity, as shown in Patent Documents 1 and 2, for example. Are known.
In the steel pipe pile of the CFT structure shown in Patent Literature 1, it is described that a stopping plate for blocking concrete is provided at the lowest position of the section to be filled with concrete.

Japanese Patent Laid-Open No. 2002-200002 describes another stopping plate structure in which a surface plate member is suspended via a steel bar that is fixed to and suspended from the head of a pile.

JP 2007-297865 A JP-A-10-311045

In the steel pipe pile of the CFT structure as shown in the above-mentioned Patent Document 1, in order to install the stop plate at a predetermined height, a stop claw or a steel ring for supporting the stop plate from below is provided inside the steel pipe. A welding manufacturing process is required. In this case, since the inside of the steel pipe is processed, there is a problem that the manufacturing process and cost increase, and there is room for improvement in this respect.

Moreover, in the case of Patent Document 2 described above, there are problems in that it is necessary to combine a plurality of steel materials as members, and that it is troublesome to install the fixing metal fittings.

The present invention has been made in view of the above-mentioned problems, and it is possible to easily install a stopping plate for filling concrete in a steel pipe pile, to improve construction efficiency, and to reduce the cost of construction. It is an object of the present invention to provide a steel pipe pile structure and a stopping plate for the steel pipe pile structure that can reduce the

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

According to the present invention, by providing a tapered portion at a position that matches the placement height of concrete, a disk-shaped stop plate having an outer diameter smaller than the upper end diameter of the tapered portion and larger than the lower end diameter can be easily attached to the tapered portion. can be installed. Therefore, it is possible to provide a stop plate that functions as a bottom cover for the concrete filled in the steel pipe pile, and a member such as a steel pipe ring for fixing the stop plate at a predetermined height inside the steel pipe pile as in the conventional method. Because welding becomes unnecessary, manufacturing processes and costs can be reduced.
Further, in the present invention, even if the pile driving depth deviates from the initial plan, it is possible to adjust the installation level of the stop plate on site by changing the diameter of the stop plate.

In the steel pipe pile structure according to the present invention, it is preferable that the upper end of the tapered portion is positioned between a pile head diameter D of the steel pipe pile and a distance of 6D or less from the pile head of the steel pipe pile.

In this case, the tapered portion is located within a distance of 6D or less from the pile head of the steel pipe pile with respect to the pile head diameter D of the steel pipe pile. Therefore, the tapered portion that reduces the cross section of the steel pipe pile can be arranged at the position where the bending moment acting on the steel pipe pile converges.

In the steel pipe pile structure according to the present invention, a tapered surface whose diameter decreases from the upper end side to the lower end side is formed on the outer peripheral edge of the stop plate, and the steel pipe pile side taper angle α of the tapered portion of the steel pipe pile , and the stop plate side taper angle β of the tapered surface of the stop plate preferably satisfies the formula (1).

In this case, the stop plate can be arranged in a state where the upper surface side of the outer peripheral edge of the stop plate is in contact with the pipe inner surface of the tapered portion. can increase

Further, in the steel pipe pile structure according to the present invention, the stop plate is provided with a guide member that protrudes downward and is supported in a state of being fitted into the steel pipe below the tapered portion of the steel pipe pile. It may be characterized by

With such a configuration, the guide member is fitted into the steel pipe below the tapered portion, so that the posture of the stop plate can be stabilized, and when the stop plate is installed, it is stopped in a stable posture. In addition to being able to arrange the plate, when the steel pipe is filled with concrete, it is possible to prevent concrete from leaking downward due to slipping of the stop plate. Therefore, it is possible to improve construction efficiency and reduce construction costs.

Further, in the steel pipe pile structure according to the present invention, the guide member, at the portion inserted into the lower steel pipe, extends from the lower end of the tapered portion of the steel pipe pile to the lower end of the guide member when the stop plate is installed. (2) is satisfied with the distance L to the steel pipe pile, and the lower end diameter of the tapered portion of the steel pipe pile is D ', in the horizontal cross section of the lower steel pipe, at least part of the guide member is 0.8D ' and the 0.9D' virtual circle, and the outer end of the guide member is not positioned outside the 0.9D' virtual circle.

With such a structure, the guide member is stably fitted into the steel pipe below the tapered portion, so the posture of the stop plate can be stabilized, and the posture stability when the stop plate is installed can be improved. In addition, it is possible to prevent the stop plate from rotating when placing concrete.

Moreover, in the steel pipe pile structure according to the present invention, the guide member may be positioned within the range of the distance L that satisfies the formula (3).

In this case, the posture of the stopping plate can be stabilized more, and the posture stability at the time of installation of the stopping plate can be improved. can be done.

Further, the stopper plate for steel pipe pile structure according to the present invention is characterized by being used in the steel pipe pile structure described above.

According to the steel pipe pile structure and the stop plate for the steel pipe pile structure of the present invention, the stop plate for filling concrete can be easily installed in the steel pipe pile, the construction efficiency can be improved, and the construction is easy. This cost can be reduced.

BRIEF DESCRIPTION OF THE DRAWINGS It is a longitudinal cross-sectional view which shows the steel pipe pile structure by 1st Embodiment of this invention. FIG. 2 is an enlarged vertical cross-sectional view of the main part of the steel pipe pile structure shown in FIG. 1; It is a perspective view of a stop plate. It is a side view of a stop plate. FIG. 11 is a side view showing an example of a stop plate with another shape; FIG. 4 shows bending moment at depth; FIG. 4 is a diagram showing the relationship between depth and bending moment for each N value; (a) to (c) are diagrams showing a method of constructing a steel pipe pile structure. It is a longitudinal cross-sectional view which shows the steel pipe pile structure by 2nd Embodiment. It is the longitudinal section which expanded the principal part of the steel pipe pile structure by 2nd Embodiment. It is a side view which shows the structure of the stopping plate by 2nd Embodiment. FIG. 7 is a horizontal cross-sectional view showing the configuration of a stop plate according to a second embodiment; (a), (b) is a figure for demonstrating the rotation angle of a stop plate. FIG. 11 is a side view showing another form of the guide member; FIG. 11 is a side view showing another form of the guide member; FIG. 11 is a side view showing another form of the guide member; FIG. 11 is a side view showing another form of the guide member; It is the longitudinal section which expanded the principal part of the steel pipe pile structure by 3rd Embodiment. FIG. 11 is a perspective view showing a stopping plate structure according to a first modified example; It is a horizontal cross-sectional view which shows the stop plate structure by a 1st modification. FIG. 11 is a perspective view showing a stop plate structure according to a second modified example; FIG. 11 is a perspective view showing a stop plate structure according to a third modified example; FIG. 11 is a horizontal cross-sectional view showing a stop plate structure according to a third modified example; (a) is a horizontal cross-sectional view of the stop plate structure according to the fourth modification as seen from below, and (b) is a stop plate structure for comparison. (a) and (b) are horizontal cross-sectional views of a stop plate structure according to a fifth modification as viewed from below. (a) and (b) are horizontal cross-sectional views of a stop plate structure according to a sixth modification as viewed from below. (a) and (b) are horizontal cross-sectional views of a stopping plate structure according to a seventh modification as viewed from below.

EMBODIMENT OF THE INVENTION Hereinafter, the stop plate for steel pipe pile structures and steel pipe pile structures by embodiment of this invention is demonstrated based on drawing.

(First embodiment)
The steel pipe pile structure 1 according to this embodiment shown in FIGS. A lid member (stopping plate 3 to be described later) is provided in the intermediate portion for blocking the concrete 4 .

The steel pipe pile structure 1 includes a steel pipe pile 2 having a tapered portion 20 whose diameter decreases from the upper end side to the lower end side, and a pipe inner surface 20c of the tapered portion 20 that is smaller than the upper end diameter D1 of the tapered portion 20 and smaller than the lower end diameter D2. A disc-shaped stopping plate 3 with a large outer diameter and concrete 4 filled above the stopping plate 3 in the steel pipe pile 2 are provided. As will be described later, when the stop plate 3 has a tapered surface on its outer peripheral edge, the diameter of the upper surface 3a of the stop plate 3 is taken as the outside diameter of the stop plate 3. As shown in FIG.

The steel pipe pile 2 has a large diameter portion 21, a tapered portion 20, and a small diameter portion 22 in order from the top. The tapered portion 20 has a reduced diameter as a whole from the lower end of the large diameter portion 21 (upper end 20a of the tapered portion 20) toward the upper end of the small diameter portion 22 (lower end 20b of the tapered portion 20). The large diameter portion 21 is a steel pipe above the tapered portion 20 . The inner diameter of the large diameter portion 21 matches the inner diameter of the upper end 20a of the tapered portion 20 (the upper end diameter D1). The small diameter portion 22 is a steel pipe below the tapered portion 20 . The inner diameter of the small diameter portion 22 matches the inner diameter of the lower end 20b of the tapered portion 20 (lower end diameter D2). The plate thickness of the steel pipe pile 2 is constant over the entire length. That is, the plate thicknesses of the large-diameter portion 21, the tapered portion 20, and the small-diameter portion 22 are constant.

The position in the height direction of the upper end 20a of the tapered portion 20 of the steel pipe pile 2 (the distance from the pile head 2A (pile upper end) of the steel pipe pile 2) is between 6D or less with respect to the pile head diameter D of the steel pipe pile 2. is set to be located in

As shown in FIGS. 1 and 2, the stopping plate 3 is arranged in the middle portion of the tapered portion 20 in the vertical direction. The stopper plate 3 has a holding force to press the concrete 4 filled in the pipe from below while being in contact with the pipe inner surface 20c of the tapered portion 20 . The stop plate 3 is formed in a plate shape made of a steel plate or a plastic plate. The stopping plate 3 may be of any material and shape, such as whether it is hollow or solid, and whether it is flat or curved or uneven, as long as it is stable when installed and has a holding force to hold down the concrete from below.

As shown in FIGS. 3 and 4, the outer peripheral edge of the stop plate 3 is formed with an inclined surface (tapered surface 3c) whose diameter gradually decreases from the upper surface 3a toward the lower surface 3b. The steel pipe pile side taper angle α (see FIG. 2) of the tapered portion 20 of the steel pipe pile 2 and the stop plate side taper angle β (see FIGS. 3 and 4) of the tapered surface 3c of the stop plate 3 are (1 ) is set to satisfy the expression

It should be noted that the stopping plate 3A shown in FIG. 5 can also employ a peripheral edge 3d in which a tapered surface is not formed on the peripheral edge. The stopping plate 3A in this case has a constant outer diameter between the upper surface 3a and the lower surface 3b. The outer diameter of the stopping plate 3A is set to be smaller than the inner diameter of the large diameter portion 21 (the upper end diameter D1 of the taper portion 20) shown in FIG. 2 and larger than the inner diameter of the small diameter portion 22 (the lower end diameter D2 of the taper portion 20). there is

Thus, in the construction of the steel pipe pile structure 1, as shown in FIG. 21 (the upper end diameter D1 of the taper portion 20) and larger than the inner diameter of the small diameter portion 22 (the lower end diameter D2 of the taper portion 20). A lid member can be provided for receiving the concrete 4 to be filled.

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.
Generally, as shown in FIG. 1, it is known that the bending moment when a horizontal force acts on the pile head 2A converges to be small with respect to the pile head diameter D from the pile head 2A to the depth of 6D or more. Therefore, by arranging the position of the upper end 20a of the tapered portion 20 within the range of 6D from the pile head portion 2A, the concrete 4 can be filled at low cost.

A two-dot chain line M shown in FIG. 1 indicates a bending moment acting on the steel pipe pile 2 .
As shown in FIG. 1, as for the specific position (height) of the tapered portion 20, it is preferable that the sudden change portion Ma of the bending moment M near the pile head portion 2A is positioned above the upper end of the tapered portion 20. That is, the tapered portion 20 is set so as to be arranged at a position where the bending moment M converges to some extent.

FIG. 6 shows a comparison of the bending moment distribution between a straight pile (solid line M1) and a tapered pile (dotted line M2) having a tapered portion in ground G with an N value of 5. FIG. 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 portion of 1 m to 1.5 m from the pile head. The magnitude of the bending moment M (kN·m) in the area of the pile head (depth of about 0 m to 1 m) is about the same between the straight pile (M1) and the 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 portion) below the tapered portion is small.

FIG. 7 shows a comparison of bending moment distributions in three types of ground with different N values (N value=2.5, 5, 10) for tapered piles. References M3, M4 and M5 indicate bending moments at N values of 2.5, 5 and 10, respectively. The vertical axis represents the absolute value of the bending moment as a ratio to the pile head moment, and the horizontal axis represents y/D using the depth (distance y) and the pile head diameter D. It can be seen that the bending moment M decreases monotonously and then slightly increases at depths of 4D to 7D with respect to the pile head diameter D, but converges below a certain value at depths of 3D to 5D.

In addition, the reduction rate of the section modulus due to diameter reduction is about 0.24 times even if the inner diameter of the small diameter part is half the pile head diameter D, but the bending moment M is reduced at a depth of 3D to 5D in each ground. It can be confirmed that the moment generated at the pile head 2A is suppressed to 0.2 times or less.
For these reasons, in practice, it is preferable to arrange the upper end position of the tapered portion 20 of the steel pipe pile 2 at 3D to 5D from the pile head portion 2A.

Next, the construction procedure of the steel pipe pile structure 1 using the stop plate 3 described above will be specifically described with reference to drawings such as FIG. 7 .
As shown in FIG. 8(a), first, the steel pipe pile 2 is press-fitted into the ground G (in the case of a blade pile, rotational press-fitting) and driven. As a method for driving the steel pipe pile 2, for example, a hollowing method, a pre-boring method, an impact method, a rotary press-in method, or the like can be applied.

Next, as shown in FIG. 8B, the stop plate 3 is lowered into the steel pipe pile 2 by a wire 5 such as a wire cable, and the stop plate 3 is installed on the pipe inner surface 20c of the tapered portion 20 of the steel pipe pile 2. (see FIG. 8(c)).
At this time, the stop plate 3 is dropped from above the steel pipe pile 2 to the pipe inner surface 20c of the tapered portion 20 in a suspended state. As shown in FIGS. 2 and 8(c), the stop plate 3 is dropped at a position where the lower end surface 4a of the concrete 4 filled in the steel pipe pile 2 becomes the upper surface 3a of the stop plate 3.
If bentonite liquid is accumulated in the cast steel pipe pile 2 before installing the stop plate 3, a weight may be attached to the stop plate 3 so that the stop plate 3 is submerged in the bentonite liquid. Alternatively, the stop plate 3 may be installed after the bentonite liquid accumulated in the steel pipe pile 2 is discharged before the stop plate 3 is installed.

Next, as shown in FIG. 8(c), the tapered surface 3c of the stop plate 3 is brought into contact with the pipe inner surface 20c of the tapered portion 20. Then, as shown in FIG. As a result, the frictional force and binding force between the inner surface 20c of the pipe and the tapered surface 3c of the stop plate 3 can be fully expressed, and the stop plate 3 serves as a bottom cover that dams the concrete 4 that is placed later from below. Can be configured. Thereafter, the bentonite liquid in the steel pipe pile 2 (not shown) is sucked up using a vacuum and discharged, a concrete pipe is inserted into the steel pipe pile 2, and concrete is poured.

After that, as shown in FIG. 8(c), concrete 4 is poured into the pile head 2A of the steel pipe pile 2 to fill it. By placing the concrete 4, the construction of the tubular structure in which the steel pipe pile 2 is filled with the concrete 4 is completed. As a result, the steel pipe pile 2 filled with the concrete 4 can have an improved yield strength as a tubular structure.

Next, the operation of the steel pipe pile structure 1 and the stopping plate 3 for the steel pipe pile structure described above will be described in detail with reference to the drawings.
As shown in FIG. 2, according to the present embodiment, by providing the taper portion 20 of the steel pipe pile 2 at a position that matches the placement height of the concrete 4, the taper portion 20 has a lower end diameter D2 that is smaller than the upper end diameter D1. A disc-shaped stopping plate 3 having a larger outer diameter can be easily installed on the tapered portion 20.例文帳に追加Therefore, it is possible to provide a stopping plate 3 functioning as a bottom cover for the concrete 4 filled in the steel pipe pile 2, and a steel pipe ring for fixing the stopping plate at a predetermined height inside the steel pipe pile as in the conventional art. Since welding of other members becomes unnecessary, the manufacturing process and cost can be reduced.
In addition, in this embodiment, even if the pile driving depth deviates from the initial plan, it is possible to adjust the installation level of the stop plate on site by changing the diameter of the stop plate 3. .

Further, in the present embodiment, the taper portion 20 is positioned between the pile head diameter D of the steel pipe pile 2 and the distance from the pile head portion 2A of the steel pipe pile 2 to 6D or less. Therefore, the tapered portion 20 that reduces the cross section of the steel pipe pile 2 can be arranged at the position where the bending moment acting on the steel pipe pile 2 converges.

Further, in the present embodiment, the steel pipe pile side taper angle α of the tapered portion 20 of the steel pipe pile 2 and the stop plate side taper angle β of the tapered surface 3c of the stop plate 3 satisfy the above equation (1). , the stop plate 3 can be arranged in a state in which the upper surface side of the outer peripheral edge of the stop plate 3 is in contact with the pipe inner surface of the tapered portion 20 . Therefore, the stopping plate 3 can be arranged in a stable posture, and the filling property of the concrete 4 can be improved.

In the steel pipe pile structure 1 and the stopping plate 3 for the steel pipe pile structure according to the present embodiment described above, the stopping plate 3 for filling the concrete 4 is easily installed by providing the steel pipe pile 2 with the taper portion 20 having a tapered shape. It is possible to improve construction efficiency and reduce construction costs.

(Second embodiment)
As shown in FIGS. 9 and 10 , in the steel pipe pile structure 1A according to the second embodiment, a cylindrical shape that protrudes downward from the lower surface 3b of the stop plate 3 and is supported while being fitted inside the steel pipe pile 2 guide member 31 is provided on the stop plate 3 (see FIG. 11).

The stop plate 3 is installed by a method of suspending it using a wire 5 (see FIG. 8(b)) after the steel pipe pile 2 is driven. At this time, a guide member 31 is attached to the lower surface 3b of the stop plate 3 to prevent the stop plate 3 from rotating and to ensure stability. As with the stop plate 3, the guide member 31 may be made of any material and shaped whether hollow or solid, as long as the stability of the stop plate 3 when installed can be ensured.

The guide member 31 is fitted in the small diameter portion 22 (lower steel pipe) at a 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 stop plate 3 is installed. (2) satisfies the formula.
Further, 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. A part exists in the region 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 located in the outer virtual circle of 0.9D'. It is set so as not to be positioned outside K2. Furthermore, it is more preferable to set the guide member 31 so as to be positioned within the range of the distance L that satisfies the 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 stop plate 3 in a plan view seen from the pipe axis O direction.

Thus, in the present embodiment, at least one or more, preferably There are two or more, more preferably three or more.

In the present embodiment, a portion (peripheral side portion) of the cylindrical guide member 31 exists in the region H as shown in FIG. In this embodiment, the guide member 31 has a cylindrical shape with the central axis C1 of the stop plate 3 as its cylindrical axis, and the central axis of the guide member 31 coincides with the pipe axis O. They are evenly distributed around the perimeter without being off-center.
Thus, when the central axis of the guide member 31 coincides with the central axis C1 of the stop plate 3, the distance d from the central axis C1 of the guide member 31 to the outer end portion 31b of the guide member 31 is a small diameter. The relationship with the inner diameter D' of the portion 22 can be expressed by equation (4).

That is, when the cylindrical guide member 31 is used as in the second embodiment, the rotation angle θ (see FIGS. 13A and 13B) of the stop plate 3 can be suppressed to about 6°. becomes.

Here, the reason why the rotation angle θ of the stopping plate 3 is less than 6° will be explained.
FIG. 13( a ) shows a cross-sectional view of the stop plate 3 installed in a posture in which the plate surface is perpendicular to the pipe axis O of the steel pipe pile 2 . The rotation angle θ at this time is 0°. The distance L′ shown in FIG. 13A indicates the distance extending in the central axis C1 direction of the guide member 31; It 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).

As shown in FIG. 13(b), a cross-sectional view when the stopping plate 3 rotates around the horizontal axis passing through the pipe axis O of the steel pipe pile 2 is shown.
In this case, since the guide member 31 contacts the inner surface 22a of the small diameter portion 22 and stops rotating, 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 FIG. 13B, the rotation angle θ is obtained by tan θ=side BC/side AB. Since AB=L' and BC≤(D'-2d)/2, tan θ is given by the following equation (5).
At this time, if L≧D′ and 2d≧0.8D′, the maximum rotation angle θ is 2d=0.8D′ and the upper end of the guide member 31 is the lower end 20b of the taper 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'). From the formula, the rotation angle is θ≦5.8°.

14 and 15 show the form of the guide member 31 that satisfies the formulas (2) and (4), and the form of the guide member 31 that satisfies the formulas (3) and (4) is shown in FIGS. It is shown in FIG.
The guide member 31A shown in FIG. 14 has a form in which the distance L is greater than zero. The guide member 31A has a small-diameter tubular portion 310 at its upper portion and a large-diameter tubular portion 311 at its lower portion. The small-diameter tubular portion 310 is arranged at the tapered portion 20 of the steel pipe pile 2 . The diameter 2d of the small-diameter tubular 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. As shown in FIG.

The guide member 31B shown in FIG. 15 has a form in which the distance L is greater than zero. The guide member 31B has large-diameter cylindrical portions 312 and 313 with the same diameter in the upper and lower portions, a small-diameter cylindrical portion 314 in the intermediate portion, a part of the large-diameter cylindrical portion 312 in the upper portion, and a large-diameter lower portion in the lower portion. The cylindrical portion 313 exists at a position deeper than the lower end 20b of the tapered portion 20, and part of the lower large-diameter cylindrical portion 313 is in a range of depth 1D' or more from the lower end 20b of the tapered portion 20 of the steel pipe pile. . The small-diameter cylindrical portion 314 is arranged in a range of less than 1D′ in the depth direction from the lower end 20 b of the tapered portion 20 . The diameter 2d of the small diameter cylindrical portion 314 may be less than 0.8D'. The diameters 2d of the upper large-diameter cylindrical portion 312 and the lower large-diameter cylindrical portion 313 are 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 .

The guide member 31C shown in FIG. 16 has a form in which the distance L satisfies the formula (3). The guide member 31C has large-diameter cylindrical portions 315 and 316 of the same diameter in the upper and lower portions, a small-diameter cylindrical portion 317 in the intermediate portion, and a portion of the large-diameter cylindrical portion 316 in the lower portion serving as the lower end of the tapered portion. is arranged in a range of 1D' or more in the depth direction from . A portion of the small-diameter cylindrical portion 317 is arranged in the tapered portion 20, and the other portion is arranged in a range of less than 1D' in the depth direction from the lower 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 there is a portion satisfying the above formula (4) at a depth of 1D' or more from the lower end of the tapered portion.

The guide member 31D shown in FIG. 17 has a form in which the distance L satisfies the formula (3). This guide member 31D has a large-diameter cylindrical portion 318 at its upper portion and a reduced-diameter portion 319 whose diameter decreases downward. are arranged in a range of 1D' or more in the vertical direction. A portion of the large-diameter cylindrical portion 318 is arranged in the tapered portion 20, and the other portion is arranged 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' as long as there is a portion that satisfies the above 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 so as to satisfy the above formula (4) at a depth of 1D' or more from the lower end of the tapered portion.

In addition, in the present embodiment, 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 the formulas (3) and (4), so the guide member 31 is Since it is stably fitted into the small diameter portion 22 rather than the taper portion 20, the posture of the stopping plate 3 can be stabilized, and the filling property of the concrete 4 can be improved.

Furthermore, in this embodiment, since the guide member 31 is fitted into the steel pipe below the tapered portion 20, the posture of the stop plate 3 can be stabilized, and the stop plate 3 can be installed in a stable posture. In addition, when concrete 4 is filled in the steel pipe, it is possible to prevent the stop plate 3 from slipping and leaking out of the concrete 4 downward. Therefore, it is possible to improve construction efficiency and reduce construction costs.

(Third embodiment)
Next, the stopping plate 3 according to the second embodiment shown in FIG. 2 described above is only required to have the strength to withstand the weight of the concrete 4 and the filling property of the concrete 4, and its material and thickness are not limited. A stop plate 3B of the third embodiment shown in FIG. 18 is thicker than the stop plate 3 of the first embodiment described above.

In the third embodiment, by increasing the thickness of the stop plate 3B, it is possible to increase the area of contact with the pipe inner surface 20c of the tapered portion 20 of the steel pipe pile 2 and improve the adhesion. As a result, it is possible to more reliably prevent the concrete 4 filled from above from flowing out below the stopping plate 3B.

(First modification)
Next, in the first stop plate structure 30A according to the first modified example shown in FIG. 19, a square prism-shaped guide member 32 having a square cross-section when viewed from above and below is placed below the non-tapered stop plate 3A of the second embodiment described above. is provided.
In the first stop plate structure 30A, the guide member 32 is inserted into the small diameter portion 22 (see FIG. 2) of the steel pipe pile 2, and the four corner portions 32a (outer ends) of the guide member 32 are formed on the inner surface of the small diameter portion 22. placed in close proximity.

In the case of the first modified example, as shown in FIG. 20, in order for the guide member 32 to exhibit its stability, the inner diameter of the small-diameter portion 22 must be 0.8 to 0.9 times the inner diameter of the small-diameter portion 22 when viewed in horizontal cross section. (the region H between the inner virtual circle K1 and the outer virtual circle K2), there are at least three positions (four positions in the first modification) through which the corners 32a of the guide member 32 pass. are doing.

(Second modification)
Next, a second stop plate structure 30B according to a second modified example shown in FIG. It is the structure which provided the guide member 33 which extended the length member 33A. In the second stopping plate structure 30B, the long member 33A of the guide member 33 is inserted into the small diameter portion 22 (see FIG. 2) of the steel pipe pile 2, and the four long members 33A are close to the inner surface of the small diameter portion 22. placed in a state.

In the case of the second modification, in order for the guide member 33 to exhibit its stability, the range of 0.8 to 0.9 times the inner diameter of the small diameter portion (see FIG. 2) (see FIG. 24 described later) (a), (b), the area H surrounded by dotted lines), the positions through which the plurality of long members 33A of the guide member 33 pass are at least three or more (four in the second modification). ) exists.

(Third modification)
Next, a third stop plate structure 30C according to a third modified example shown in FIG. 22 has a configuration in which a guide member 34 made of H-shaped steel is provided on the lower surface 3b of the non-tapered stop plate 3A of the above-described second embodiment. be. The axial direction of the guide member 34 is orthogonal to the lower surface 3b of the stop plate 3A. In the third stop 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 corner portions 34a (outer end portions) of the guide member 34 are provided on the inner surface of the small diameter portion 22. are placed in close proximity.

In the case of the third modification, as shown in FIG. 23, in order for the guide member 34 to exhibit its stability, the inner diameter of the small diameter portion (see FIG. 2) must be 0.8 to 0.9 times (the region H between the inner virtual circle K1 and the outer virtual circle K2), there are at least three positions (four positions in the third modification) through which the corners 34a of the guide member 34 pass. are doing.

(Fourth modification)
Next, a fourth stop plate structure 30D according to a fourth modified example shown in FIG. 24(a) has a triangular cross section when viewed from above and below the non-tapered stop plate 3A of the second embodiment described above. It has a configuration in which a triangular prism-shaped guide member 35 is provided. In the fourth stop 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 corner portions 35a (outer end portions) of the guide member 35 are placed on the inner surface of the small diameter portion 22. are placed in close proximity.

In the case of the fourth modified example, in order for the guide member 35 to exhibit its stability, the guide member 35 must be provided with respect to the region H which is 0.8 to 0.9 times the inner diameter of the small diameter portion 22 (see FIG. 2). There are at least three positions (three positions in the fourth modification) through which the corner portion 35a of the member 35 passes.
In the case of a plate-shaped guide member 36 having an I-shaped cross-section when viewed from above and below the non-tapered stop plate 3A as shown in FIG. ), there are two positions through which the end portion 36a of the guide member 36 passes in the region H, which is 0.8 to 0.9 times the inner diameter of ), so it is difficult to obtain stability as a guide.

Next, in a fifth modification shown in FIGS. 25(a) and (b), the ends of the guide members 41 and 42 are not arranged equidistantly from the central axis (pipe axis O) of the stopping plate. .
The guide member 41 in FIG. 25(a) has an isosceles triangular cross-section, and three apexes 41a, 41b, and 41c each extend from an inner virtual circle K1 of 0.8D' and an outer virtual circle K2 of 0.9D', respectively. It exists in the region H between In this case, only one top portion 41a is the outer end portion that is the farthest from the tube axis O when viewed from the tube axis direction.

The guide member 42 in FIG. 25(b) has an equilateral triangular cross-section, and three apexes 42a, 42b, and 42c each form a 0.8D' inner virtual circle K1 and a 0.9D' outer virtual circle K2. It exists in the region H between In this case, the two apex portions 42b and 42c are the outer end portions that are farthest from the tube axis O when viewed from the tube axis direction.

Next, a sixth modification 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 displaced.
The guide member 43 shown in FIG. 26(a) has an equilateral triangular cross-section, and three apexes 43a, 43b, and 43c each form an inner virtual circle K1 of 0.8D′ and an outer virtual circle K2 of 0.9D′. It exists in the region H between In this case, one top portion 43a of the three top portions 43a, 43b, and 43c is the outer end portion that is the farthest from the tube axis O when viewed from the tube axis direction.

The guide member 44 shown in FIG. 26(b) has a square cross section, and four apexes 44a, 44b, 44c, and 44d each have an inner virtual circle K1 of 0.8D' and an outer virtual circle K2 of 0.9D'. It exists in the region H between In this case, two of the four top portions 44a, 44b, 44c, and 44d are the outer end portions that are farthest from the tube axis O when viewed in the tube axial direction.

Next, a seventh modification shown in FIGS. 27(a) and 27(b) has a configuration in which only a part of the tops of the guide members 45 and 46 exists in the region H described above.
The guide member 45 in FIG. 27(a) has an equilateral triangular cross section, and only one of the three apexes 45a, 45b, and 45c has an inner virtual circle K1 of 0.8D′ and an inner virtual circle K1 of 0.9D′. It exists in the region H between the outer virtual circle K2, and the other two apexes 45b and 45c exist inside the inner virtual circle K1. In this case, one top portion 45a of the three top portions 45a, 45b, and 45c is the outer end portion that is farthest from the tube axis O when viewed from the tube axis direction.
Thus, even if there is only one outer end, the presence of that one outer end (top 45a) in region H has the effect of preventing rotation in a specific direction.

The guide member 46 in FIG. 27(b) has a rectangular cross section, and two of the four apexes 46a, 46b, 46c, 46d are located on the inner virtual circle K1 of 0.8D' and 0.9D. ' and the outer virtual circle K2, and the other two apexes 46c and 46d exist inside the inner virtual circle K1. In this case, the two apex portions 46a and 46b are the outer end portions that are farthest from the tube axis O when viewed from the tube axis direction.

Although the embodiments of the steel pipe pile structure and the stopping plate for the steel pipe pile structure according to the present invention have been described above, the present invention is not limited to the above-described embodiments, and can be changed as appropriate without departing from the scope of the invention. be.

For example, in the present embodiment, the upper end 20a of the tapered portion 20 of the steel pipe pile 2 is positioned between the pile head diameter D of the steel pipe pile 2 and the distance from the pile head 2A of the steel pipe pile 2 to 6D or less. However, it is not limited to this.

Further, in the present embodiment, a tapered surface 3c whose diameter is reduced from the upper end side to the lower end side is formed on the outer peripheral edge of the stop plate 3, and the steel pipe pile side taper angle α of the tapered portion 20 of the steel pipe pile 2 and the stop plate The stop plate side taper angle β of the tapered surface 3c of 3 satisfies the above formula (1), but is not limited to this.

Further, the stop plate 3 is provided with a guide member 31 that protrudes downward and is supported while being fitted inside the steel pipe pile 2, but such a guide member 31 can be omitted. is. That is, the configuration may be such that only the disk-shaped stop plate 3 is provided.

Further, in the present embodiment, the guide member 31 has a distance d from the center of the stop plate 3 to the outer end portion 31b of the guide member 31, an inner diameter D′ of the lower end of the tapered portion 20 of the steel pipe pile 2, and the stop plate The relationship between 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 at the time of installation of the above formula (2) (formula (3)) and (4). However, it is not limited to this. Further, in the present embodiment, the above formula (2) is satisfied, and in the horizontal cross section of the small diameter portion 22, at least a portion of the guide member has an inner virtual circle K1 of 0.8D′ and an outer virtual circle K2 of 0.9D′. and the outer end of the guide member is set so as not to be located outside the outer virtual circle K2 of 0.9D', but is not limited to this.

Moreover, the length, quantity, and shape of the stopping plate 3 can be set arbitrarily.

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

In addition, it is possible to appropriately replace the components in the above-described embodiments with well-known components without departing from the scope of the present invention.

1 Steel pipe pile structure 2 Steel pipe piles 3, 3A, 3B Stopping plate 4 Concrete 20 Taper part 20c Pipe inner surface 21 Large diameter part 22 Small diameter part 30A to 30E Stopping plate structure 31 Guide member

Claims (7)

a steel pipe pile having a tapered portion whose diameter decreases from the upper end side to the lower end side;
a disc-shaped stopping 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;
Concrete filled above the stopping plate in the steel pipe pile;
A steel pipe pile structure comprising: 2. The steel pipe pile according to claim 1, wherein the upper end of the tapered portion is positioned between a pile head diameter D of the steel pipe pile and a distance of 6D or less from the pile head of the steel pipe pile. structure. A tapered surface whose diameter decreases from the upper end side to the lower end side is formed on the outer peripheral edge of the stop plate,
The steel pipe pile side taper angle α of the tapered portion of the steel pipe pile and the stop plate side taper angle β of the tapered surface of the stop plate satisfy formula (1). Steel pipe pile construction as described.

4. The method according to any one of claims 1 to 3, wherein the stop plate is provided with a guide member that protrudes downward and is supported in a state of being inserted into the steel pipe below the tapered portion of the steel pipe pile. The steel pipe pile structure according to any one of items 1 and 2. In the portion fitted into the lower steel pipe, the guide member has a distance L from the lower end of the tapered portion of the steel pipe pile to the lower end of the guide member when the stop plate is installed, and satisfies formula (2). ,
When the lower end diameter of the tapered portion of the steel pipe pile is D', at least part of the guide member is a virtual circle of 0.8D' and a virtual circle of 0.9D' in the horizontal cross section of the lower steel pipe. 5. The steel pipe pile structure according to claim 4, wherein the outer end of the guide member is not located outside the virtual circle of 0.9D′.

The steel pipe pile structure according to claim 5, wherein the guide member is positioned within the range of the distance L that satisfies the formula (3).

A stopping plate for a steel pipe pile structure, characterized by being used in the steel pipe pile structure according to any one of claims 1 to 6.

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