JP2009127267A - Steel pipe pile with widened bottom - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a steel pipe pile with a widened bottom, which is low in manufacturing cost, good in excavating efficiency, and excellent in vertical support force. <P>SOLUTION: The steel pipe pile 1 with the widened bottom has a steel pipe 2 and a widened bottom plate 3 mounted on a distal end face of the steel pipe 2. The widened bottom plate 3 is formed of an almost square steel plate which has the center of gravity thereof located at an axial center of the steel pipe and point-symmetrical about the center of gravity. The widened bottom plate 3 has upward inclined surface portions 31 and downward inclined surface portions 32 which are formed in the following manner. An area of the steel plate outside the periphery of the steel pipe 2 is cut beginning from mutually facing two sides (first and third sides) of a peripheral edge in a direction perpendicular to the two sides, and line segments connecting between terminal points of cut lines and the other two sides (second and fourth sides) of the peripheral edge, that are in parallel with the cut lines of the steel plate, are defined as folding lines. Then the upward inclined surface portions 31 are each set up by folding a portion of the area, on one side of the cut line close to a rotating directional side, so as to be inclined toward an axially rear side of the steel pipe. On the other hand, the downward inclined surface portions 32 are each set up by folding a portion of the area, on one side of the cut line opposite to the rotating directional sides, so as to be inclined toward an axially front side of the steel pipe. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a bottomed steel pipe pile that is rotationally pressed into the ground by a rotational force and a pressing force.

  Conventionally, there are steel pipe piles with various shapes such as those with an expanded bottom part, but generally screw type with a spiral structure in which continuous blades are welded and fixed to the side of the steel pipe, two pieces A two-blade type in which the blades are fixed at different gradients, a type in which a blade is cut for excavation, a type in which a steel pipe is compressed and twisted are used. And various structures including the thing of a cast structure are proposed for the bottom expansion blade which comprises the said bottom expansion part.

  Any of the above-mentioned types of steel pipe piles have a track record, but the screw type is excellent in excavation performance, has high support performance, has a track record, and is widely known. However, in order to process into a screw shape, these structures require large-scale equipment such as hollowing out a disk into a donut shape or forming it into a spiral shape with a large press machine, and a factory with no equipment It is not suitable for manufacturing in Japan. In addition, the processing cost is high.

  And as a technique which simplifies a bottom-expansion part, the steel pipe pile (patent document 1) which can be manufactured simply and cheaply and was high intensity | strength and excellent in excavation property is reported. In Patent Document 1, an excavating blade is formed by making a cut in a radial direction and a circumferential direction in a circular or polygonal lower plate member and bending it up and down. However, the extended cutting distance is long and complicated, and the bending process is complicated. As a result, the effect of reducing the material cost and the processing cost is hindered.

JP 2004-278306 A

  The present invention has been made in view of conventional problems, and is intended to provide a bottomed steel pipe pile that has good excavability and excellent vertical support force while being low in manufacturing cost. is there.

The present invention is a bottomed steel pipe pile that is rotationally press-fitted into the ground by rotational force and pressing force,
The bottomed steel pipe pile has a steel pipe and a bottomed plate attached to the tip surface of the steel pipe,
The bottom plate is made of a substantially square steel plate, and its center of gravity is located at the axis of the steel pipe, and is arranged so as to be point-symmetric with respect to the center of gravity,
The bottom expansion plate is provided with a cut in the vertical direction from two sides (first side and third side) opposite to the outer edge outside the outer periphery of the steel pipe of the steel plate, and the end point of the cut and the steel plate A line segment connecting points on the other two sides (second side and fourth side) parallel to the incision is defined as a fold line, and a portion located on the rotational direction side from the above incision during rotational press-fitting is axial. An upward inclined surface portion formed by bending so as to incline toward the rear end side, and a downward inclined surface portion formed by bending a portion located on the opposite side in the rotational direction from the above-mentioned cut so as to incline toward the axial front end side. It is in an expanded steel pipe pile characterized by having (claim 1).

  The above-mentioned bottomed steel pipe pile is obtained by attaching a bottomed plate having the above-mentioned specific shape to a steel pipe, has good excavability when being rotationally pressed into the ground, and has a vertical bearing capacity after installation. It is also excellent. Moreover, since the structure of the said bottom expansion board can be simplified and manufactured, manufacturing cost can be restrained low.

  The bottomed steel pipe pile has a steel pipe and a bottomed plate attached to the tip surface of the steel pipe, the bottomed plate is made of a substantially square steel plate, and its center of gravity is located at the axis of the steel pipe. In addition, the steel pipe is disposed on the front end surface so as to be point-symmetric with respect to the center of gravity. For this reason, the bottom expanded portion is balanced, and a stable vertical support force can be obtained after rotational press-fitting.

  Moreover, the said bottom expansion board is provided with the notch | incision in the perpendicular direction from two sides (1st edge | side and 3rd edge | side) which face each other among four sides of an outer edge outside the outer periphery of the said steel pipe of the said steel plate. Then, a line segment connecting the end point of the cut and a point on the other two sides (second side and fourth side) of the outer edge parallel to the cut of the steel sheet is used as a bending line, and the cut is made at the time of rotational press-fitting. An upward inclined surface portion formed by bending a portion located on the rotational direction side to be inclined toward the rear end side in the axial direction, and a portion located on the opposite side in the rotational direction with respect to the notch are inclined toward the distal end side in the axial direction. And a downwardly inclined surface portion formed by bending the same.

  In other words, the upward inclined surface portion is provided so as to extend downward in the direction opposite to the rotational direction so that the downward inclined surface portion extends downward in the rotational direction. Then, by rotating the bottomed steel pipe pile using rotation and pressing means, the downward inclined surface portion functions as a propelling means for excavating and softening the earth and sand, and the upward inclined surface portion functions to push up the softened earth and sand. Drain the soil above and to the side of the confirmation plate.

  In this way, the gradient formed by combining the downward inclined surface portion and the upward inclined surface portion excavates the earth and sand well when rotating using the rotation and pressing means, and the earth and sand is upward in the direction opposite to the rotation direction. It can guide and perform smooth press-fitting. Moreover, even if a wide area bottom plate is provided, the downward inclined surface portion and the upward inclined surface portion can satisfactorily engrave the soil. Since it can be set as a base plate with a wide area, stability after installation can be obtained.

  Moreover, the said bottom expansion board can obtain a bottom expansion board by incising into one flat steel plate and giving a simple process of bending. Moreover, the welding distance at the time of attaching the said bottom expansion board to a steel pipe is also short. For this reason, since the utilization efficiency of material is very high, the complexity of processing is low, and equipment such as an expensive press machine is not necessary, the material cost per one can be kept low. Thus, since the structure of a bottom expansion board and a bottom expansion steel pipe pile can be simplified, a manufacturing cost can be restrained low and an inexpensive bottom expansion steel pipe pile can be obtained easily.

Moreover, the said bottom expansion steel pipe pile has the said bottom expansion plate attached to the front end surface of the said steel pipe, and the front-end | tip part of the said steel pipe is obstruct | occluded. Therefore, it can have a high supporting force.
Thus, according to the present invention, it is possible to provide a bottomed steel pipe pile that has good excavability and excellent vertical support force while being low in manufacturing cost.

As described above, the bottomed steel pipe pile has a steel pipe and a bottomed plate attached to the tip surface of the steel pipe. The widened plate is made of a substantially square steel plate, and its center of gravity is located at the axial center of the steel pipe, and is arranged so as to be symmetric with respect to the center of gravity.
The bottom plate is preferably attached to the tip surface of the steel pipe by welding.
Moreover, the magnitude | size, thickness, raw material, etc. of the steel plate used for the said bottom expansion board can be suitably selected according to a use etc.

It is preferable that the steel plate has a side dimension 2 to 3 times the outer diameter of the steel pipe.
In this case, it is possible to sufficiently ensure excavability at the time of rotary press-fitting and to obtain a stable vertical support force after rotary press-fitting.
When the side dimension of the steel plate is less than twice the outer diameter of the steel pipe, there is a possibility that the vertical supporting force after the arrangement cannot be obtained sufficiently. On the other hand, when the side dimension of the steel sheet exceeds three times the outer diameter of the steel pipe, the resistance during rotary press-fitting increases and the excavability may be reduced.

Moreover, it is preferable that the said steel plate is 9-16 mm in thickness (Claim 8).
In this case, a stable vertical support force can be ensured.
When the thickness of the steel sheet is less than 9 mm, the downward inclined surface portion may not have sufficient strength for excavation of earth and sand at the time of rotary press-fit, or the vertical support force at the time of installation may not be sufficiently obtained. There is. On the other hand, when the thickness of the steel sheet exceeds 16 mm, the cost may increase.

  When the center of gravity of the steel plate is not located at the axial center of the steel pipe, or when the bottom plate is not arranged so as to be symmetric with respect to the center of gravity, a stable rotational operation can be obtained at the time of rotary press-fitting. There is a problem that can not be.

Further, as described above, in order to provide the upward inclined surface portion and the downward inclined surface portion, the bottom expansion plate is provided with cuts in the vertical direction from two opposite sides (first side and third side). Preferably, the cut is formed on a line segment connecting midpoints of two opposing sides (first side and third side) of the steel sheet (Claim 2).
In this case, the areas of the upward inclined surface portion and the downward inclined surface portion can be easily set to be the same.

Moreover, it is preferable that the bend line is formed perpendicular to the notch.
In this case, both the upward inclined surface portion and the downward inclined surface portion can be substantially rectangular.

Further, the fold line may be a line segment connecting the end point of the cut and a midpoint of two sides (second side and fourth side) parallel to the cut of the steel sheet. ).
In this case, the area occupied by the upward inclined surface portion and the downward inclined surface portion of the bottom expansion plate can be increased.

  And the shape and area of the upward inclined surface portion and the downward inclined surface portion can be changed by adjusting the position of the notch and the position of the fold line, and this depends on the geology of the land into which the bottomed steel pipe pile is pressed. It may be changed.

Moreover, it is preferable that the inclination | tilt angle of the said downward inclined surface part is 15-45 degrees with respect to the radial direction orthogonal to the axial center of the said steel pipe.
In this case, it is possible to perform rotary press-fitting with good excavability and to obtain a stable vertical support force after rotary press-fitting.

When the inclination angle of the upward inclined surface portion is less than 15 ° with respect to the radial direction orthogonal to the axis of the steel pipe, when the bottomed steel pipe pile is rotationally press-fitted, the sediment of the downward inclined surface portion is excavated. It cannot be performed well, and the resistance in the penetration direction increases, and the excavability may be reduced. On the other hand, when the tilt angle exceeds 45 °, when the bottomed steel pipe pile is rotationally press-fitted, resistance to the rotational direction is increased, and excavation performance may be deteriorated. The power may be reduced.
Note that the above-described angle allows some errors.

Moreover, it is preferable that the inclination | tilt angle of the said upward inclined surface part is 15-45 degrees with respect to the radial direction orthogonal to the axial center of the said steel pipe (Claim 6).
In this case, it is possible to satisfactorily push up the earth and sand during the rotary press-fit, and to obtain a stable vertical support force after the rotary press-fit.

When the inclination angle of the downward inclined surface portion is less than 15 ° with respect to the radial direction orthogonal to the axis of the steel pipe, it is difficult to obtain the effect of pushing up earth and sand during rotary press-fitting, and resistance to the penetration direction is large. Therefore, there is a risk of reducing the excavability. On the other hand, when the inclination angle exceeds 45 °, the vertical supporting force after the arrangement may be reduced.
Note that the above-described angle allows some errors.

Further, it is preferable that a cutting blade for excavation projecting in the axial direction is disposed at the center of the surface of the bottom plate.
Since it has the said cutting blade for excavation, penetrability can be improved.
As the cutting blade for excavation, for example, a plate material having a substantially pentagonal shape or a substantially triangular shape is preferably provided so as to protrude in the axial direction at the center of the surface of the bottomed plate.

Moreover, the said steel pipe has a joint part for connecting a steel pipe, and it is preferable that this joint part is subjected to diameter expansion processing by cold working (Claim 10).
In this case, a joint part can be provided easily and cheaply compared with the case where a joint part whose diameter has been expanded in advance by casting is provided, and the price of the above-described bottomed steel pipe pile can be further reduced.

  Specifically, the joint portion is formed so that the rear end portion of the steel pipe is subjected to a diameter expansion process by cold working so as to have an inner diameter that is about 1 to 3 mm larger than the outer dimension of the front end portion of the steel pipe to be connected. A steel pipe can be connected and extended by inserting the tip part of the steel pipe connected to this joint part, and fixing using a bolt etc.

(Example 1)
This example demonstrates the Example concerning the bottom expanded steel pipe pile of this invention using FIGS. 1-3.
The expanded bottom steel pipe pile 1 of this example is a rotary buried pile 1 that is rotationally press-fitted into the ground by a rotational force and a pressing force.
As shown in FIG. 1, the bottomed steel pipe pile 1 has a steel pipe 2 and a bottomed plate 3 attached to the tip surface of the steel pipe 2.

  As shown in FIG. 1 to FIG. 3, the bottom plate 3 is composed of a substantially square steel plate 33 in which four sides (first side, second side, third side, fourth side) are successively connected to the outer edge, The center of gravity is located at the axial center of the steel pipe 2 and is arranged so as to be symmetric with respect to the center of gravity. The bottom expansion plate 3 is provided with incisions 34 in the vertical direction from the two sides (the first side 36 and the third side 38) facing the outer edges outside the outer periphery 23 of the steel pipe of the steel plate 33, and the end point of the incision 34 and the steel plate A line segment connecting the other two sides (second side 37 and fourth side 39) of the outer edge that is parallel to the notch is defined as a fold line 35 and is positioned on the rotational direction side with respect to the notch 34 at the time of rotational press-fitting. The upward inclined surface portion 31 formed by bending the part so as to incline toward the rear end side in the axial direction, and the part located on the opposite side in the rotational direction from the notch 34 are bent so as to incline toward the front end side in the axial direction. And a downwardly inclined surface portion 32 formed.

The manufacturing method of the said bottom expanded steel pipe pile 1 is demonstrated.
First, as the steel pipe 2, a steel pipe made of a general structural carbon steel pipe STK400, having a diameter of 89.1 mm, a thickness of 4.2 mm, and a length of 350 mm was prepared.
Next, one end of the steel pipe 2 was subjected to a diameter expansion process by cold working so that the inner diameter became 91.5 mm, and the joint portion 21 was formed. Bolt insertion holes 22 are provided on the side surfaces of the joint portion 21.

In addition, as the steel plate 33 for the bottom expansion plate 3, a substantially square planar steel plate made of a general structural steel plate SS400, having a width W of 250 mm, a length L of 250 mm, and a thickness of 12 mm was prepared.
Then, as shown in FIG. 2, outside the outer periphery 23 of the steel pipe of the steel plate 33, 75 mm on a line segment connecting the midpoints of the two opposite sides (the first side 36 and the third side 38) of the steel plate 33. A cut 34 was formed. A fold line 35 was formed perpendicular to the cut 34.

Thereafter, as shown in FIG. 2 and FIG. 3, a portion located on the rotation direction A side with respect to the notch 34 at the time of rotational press-fitting is bent so as to incline toward the rear end side in the axial direction to form an upward inclined surface portion 31. A downwardly inclined surface portion 32 was formed by bending a portion located on the opposite side of the rotation direction from the notch 34 so as to be inclined toward the tip end side in the axial direction.
The inclination angle 32 of the downward inclined surface portion was bent so as to be 30 ° with respect to the radial direction perpendicular to the axis of the steel pipe 2. Further, the inclination angle of the upward inclined surface portion 31 was bent so as to be 30 ° with respect to the radial direction orthogonal to the axis of the steel pipe 2.

Further, the excavation cutting blade 4 is made of a general structural steel plate SS400, and the size is as shown in FIG. 1, a = 80 mm, b = 80 mm, c = 40 mm, d = 40 mm, e = 40 mm, f = A pentagonal shape having a thickness of 40 mm and a thickness of 9 mm was prepared.

Next, the steel plate 2 that has been subjected to the diameter expansion treatment is subjected to complete penetration welding of the bottom expansion plate 3 with respect to the tip surface of the steel pipe 2 at the tip portion on the side that has not been subjected to the diameter expansion treatment. The center of gravity of 33 is positioned at the axial center of the steel pipe 2 and is fixed so as to be point-symmetric with respect to the center of gravity.
Next, as shown in FIG. 1, the cutting blade 4 for excavation was arranged by welding so as to protrude in the axial direction at the center of the surface of the bottom expansion plate 3 attached to the tip end surface of the steel pipe 2.

  Further, as shown in FIG. 1, the inclination angle α of the upward inclined surface portion 31 is 30 ° with respect to the radial direction orthogonal to the axis, and the inclination angle β of the downward inclined surface portion 32 is the axis center. It is 30 degrees with respect to the radial direction orthogonal to.

As described above, the bottomed steel pipe pile 1 of this example can be manufactured at a low manufacturing cost because it basically only performs the welding process.
Note that the order of the above manufacturing procedures can be changed as appropriate.

Next, the obtained bottom expanded steel pipe pile 1 was driven into the ground.
The bottomed steel pipe pile 1 of this example showed good excavability and vertical supporting force.
Thus, according to the present invention, it can be seen that a bottomed steel pipe pile having good excavability and excellent vertical support force can be provided while the manufacturing cost is low.
Moreover, when digging deeply, the steel pipe for connection can be inserted in the joint part 21 which performed the diameter expansion process, and it can contact using a volt | bolt.

(Example 2)
In this example, as shown in FIGS. 4 and 5, the shape of the bottom expansion plate 3 of Example 1 is changed. Others were performed in the same manner as in Example 1.
In this example, the bottom expansion plate 5 was produced using the same steel plate as the steel plate 33 of Example 1 above.
As shown in FIG. 4, the bottom expansion plate 5 is cut at the time of rotational press-fitting on the two sides (the first side 36 and the third side 38) opposite to the outer edges of the steel plate 33 outside the outer periphery 23 of the steel pipe of the steel plate 33. A cut 51 was formed at a position where the length X of the portion located on the rotation direction A side from 51 is 75 mm, and a fold line 52 was formed perpendicular to the cut 51.

After that, as shown in FIG. 5, the portion located on the rotation direction A side with respect to the notch at the time of rotational press-fitting is bent so as to incline toward the rear end side in the axial direction to form an upward inclined surface portion 53, which rotates more than the notch. A downwardly inclined surface portion 54 was formed by bending a portion located on the opposite side in the direction so as to be inclined toward the tip end side in the axial direction.
The downward inclined surface portion 54 was bent so that the inclination angle was 15 ° with respect to the radial direction perpendicular to the axis of the steel pipe. Moreover, the inclination angle of the upward inclined surface portion 53 was bent so as to be 30 ° with respect to the radial direction orthogonal to the axis of the steel pipe.

  Similarly to the bottomed steel pipe pile 1 of the above Example 1, the bottomed steel pipe pile of this example also has good excavability and excellent vertical support force while being low in manufacturing cost.

(Example 3)
In this example, as shown in FIGS. 6 and 7, the shape of the bottom expansion plate 3 of the first embodiment is changed. Others were performed in the same manner as in Example 1.
In this example, the bottom expansion plate 6 was produced using the same steel plate as the steel plate 33 of Example 1 above.
As shown in FIG. 6, the expanded bottom plate 6 connects the midpoints of the two sides (the first side 36 and the third side 38) facing the outer edges of the steel plate 33 outside the outer periphery 23 of the steel pipe of the steel plate 33. A notch 61 is formed on the line segment, and the end point of the notch 61 and the midpoint of the other two sides (second side 37 and fourth side 39) of the outer edge of the steel plate 33 that are parallel to the notch 61. A connecting line segment was a fold line 62.

After that, as shown in FIG. 7, the portion located on the rotation direction A side than the notch at the time of rotational press-fitting is bent so as to incline toward the rear end side in the axial direction to form an upward inclined surface portion 63, which rotates more than the notch. A downwardly inclined surface portion 64 was formed by bending a portion located on the opposite side in the direction so as to be inclined toward the tip end in the axial direction.
The inclination angle of the downward inclined surface portion 64 was bent so as to be 15 ° with respect to the radial direction orthogonal to the axis of the steel pipe. Further, the inclination angle 63 of the upward inclined surface portion was bent so as to be 15 ° with respect to the radial direction perpendicular to the axis of the steel pipe.

  Similarly to the bottomed steel pipe pile 1 of the above Example 1, the bottomed steel pipe pile of this example also has good excavability and excellent vertical support force while being low in manufacturing cost.

Explanatory drawing which shows the bottom expanded steel pipe pile in Example 1. FIG. Explanatory drawing which shows the steel plate for bottom expansion boards in Example 1. FIG. Explanatory drawing which shows the bottom expansion board in Example 1. FIG. Explanatory drawing which shows the steel plate for bottom expansion boards in Example 2. FIG. Explanatory drawing which shows the bottom expansion board in Example 2. FIG. Explanatory drawing which shows the steel plate for bottom expansion boards in Example 3. FIG. Explanatory drawing which shows the bottom expansion board in Example 3. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Expanded steel pipe pile 2 Steel pipe 3 Expanded plate 31 Upward inclined surface part 32 Downward inclined surface part 4 Cutting edge for excavation

Claims (10)

An expanded steel pipe pile that is rotationally pressed into the ground by rotational force and pressing force,
The bottomed steel pipe pile has a steel pipe and a bottomed plate attached to the tip surface of the steel pipe,
The bottom plate is made of a substantially square steel plate, and its center of gravity is located at the axis of the steel pipe, and is arranged so as to be point-symmetric with respect to the center of gravity,
The bottom expansion plate is provided with a cut in the vertical direction from two sides (first side and third side) opposite to the outer edge outside the outer periphery of the steel pipe of the steel plate, and the end point of the cut and the steel plate A line segment connecting points on the other two sides (second side and fourth side) parallel to the incision is defined as a fold line, and a portion located on the rotational direction side from the above incision during rotational press-fitting is axial. An upward inclined surface portion formed by bending so as to incline toward the rear end side, and a downward inclined surface portion formed by bending a portion located on the opposite side in the rotational direction from the above-mentioned cut so as to incline toward the axial front end side. Expanded bottom steel pipe pile characterized by having.   2. The expanded steel pipe pile according to claim 1, wherein the cut is formed on a line segment connecting midpoints of two opposite sides (first side and third side) of the steel plate.   3. The expanded steel pipe pile according to claim 1, wherein the fold line is formed perpendicular to the notch.   In Claim 1 or 2, the bending line is a line segment connecting the end point of the cut and the midpoint of two sides (second side and fourth side) parallel to the cut of the steel plate. A featured expanded steel pipe pile.   5. The expanded steel pipe pile according to claim 1, wherein an inclination angle of the downward inclined surface portion is 15 to 45 ° with respect to a radial direction orthogonal to an axis of the steel pipe.   6. The expanded steel pipe pile according to claim 1, wherein an inclination angle of the upward inclined surface portion is 15 to 45 ° with respect to a radial direction orthogonal to an axis of the steel pipe.   The rotary buried pile according to any one of claims 1 to 6, wherein the steel sheet has a side dimension that is two to three times the outer diameter of the steel pipe.   The rotary buried pile according to any one of claims 1 to 7, wherein the steel sheet has a thickness of 9 to 16 mm.   The rotary buried pile according to any one of claims 1 to 8, wherein a cutting blade for excavation projecting in the axial direction is disposed at the center of the surface of the bottom plate.   The steel pipe according to any one of claims 1 to 9, wherein the steel pipe has a joint part for connecting the steel pipes, and the joint part is subjected to a diameter expansion process by cold working. Rotating buried pile.

Images