JP5700895B1 - Screwed steel pipe pile - Google Patents

Abstract

A plurality of steel plates 20 a and 20 b formed by dividing a circular steel plate having an outer diameter larger than that of the cylindrical steel pipe 10 into a substantially fan shape is inclined with respect to a direction orthogonal to the axial direction of the steel pipe 10. It is a screw-in type steel pipe pile attached along the circumferential direction of the steel pipe 10, Comprising: It is radial direction rather than steel plate 20a, 20b in the inclination lower end part 21a, 21b used as the most tip among several steel plate 20a, 20b. The sacrificial member 25 is provided so as to protrude outward.

Description

  The present invention relates to a screwed steel pipe pile.

  Conventionally, as a screwed steel pipe pile embedded in the ground by the action of a screw by applying a rotational force, as shown in FIG. 10 (a) and FIG. One having two steel plates 200a and 200b in the illustrated example is known. In addition, in the screwed-type steel pipe pile shown in these FIG.10 and FIG.11, the front end side is demonstrated as a downward direction, and a pile head side is demonstrated as an upper direction.

  The steel pipe 100 has a cylindrical shape having a hollow portion 110 inside. A plurality of (two in the illustrated example) attachment portions 120 a and 120 b are formed at the tip of the steel pipe 100. The attachment portions 120a and 120b are respectively formed at the distal end portion of the steel pipe 100 along the circumferential direction. These mounting portions 120a and 120b constitute inclined surfaces in which the respective front end surfaces are gradually inclined downward from one side to the other side in the circumferential direction. The attachment portions 120a and 120b illustrated here have the same extension length of the tip surface and the inclination angle of the tip surface.

  Each of the steel plates 200a and 200b has a semicircular shape formed by dividing a circular steel plate having an outer diameter larger than that of the steel pipe 100 into two. One steel plate 200a is attached along the one front end face so as to be inclined with respect to a direction orthogonal to the axial direction of the steel pipe 100. The outer peripheral portion of the steel plate 200a protrudes outward in the radial direction of the steel pipe 100, as shown in FIG. 10B and FIG. 11B.

  The other steel plate 200b is attached along the other front end surface so as to be inclined with respect to the direction orthogonal to the axial direction of the steel pipe 100. The outer peripheral portion of the steel plate 200b protrudes toward the outside in the radial direction of the steel pipe 100, as shown in FIG. 10 (b) and FIG. 11 (b).

  And as above-mentioned, since the two attachment parts 120a and 120b have the same extension length and inclination angle of a front end surface, the steel plates 200a and 200b attached to the attachment parts 120a and 120b respectively. The inclination angles are also equal to each other.

  When a rotational force is applied around the central axis L of the steel pipe 100, the screw-type steel pipe pile having such a configuration is embedded in the ground by the action of screws by the protruding portions of the steel plates 200a and 200b (for example, Patent Documents). 1).

JP-A-9-324419

  By the way, in the screwed-type steel pipe pile proposed in Patent Document 1 as described above, the steel plates 200a and 200b are each attached to the direction perpendicular to the axial direction of the steel pipe 100. The steel plate 200a has an inclined lower end portion 210a and an inclined upper end portion 220a, and the other steel plate 200b has an inclined lower end portion 210b and an inclined upper end portion 220b. And when a rotational force is given to the screw-type steel pipe pile around the central axis L of the steel pipe 100, in one steel plate 200a, the inclined lower end portion 210a becomes a portion that first penetrates into the ground, and the other steel plate. In 200b, the inclined lower end portion 210b is a portion that first penetrates into the ground. As described above, the inclination angles of the two steel plates 200a and 200b are equal to each other, and therefore, the inclined lower end portion 210a and the inclined lower end portion 210b are the lowermost portions of the two steel plates 200a and 200b. Thus, the two steel plates 200a and 200b become the first end portion that first penetrates into the ground.

  Moreover, in the said screwed-type steel pipe pile, since steel plate 200a, 200b is inclined and attached with respect to the direction orthogonal to the axial direction of the steel pipe 100, the central axis L of the steel pipe 100 is with respect to the ground. When arranged so as to be orthogonal to each other, as shown in FIG. 10C and FIG. 11C, the projection shape of the steel plates 200a and 200b on the ground becomes an ellipse. In this case, a line segment E connecting the inclined lower end portion 210a and the inclined upper end portion 220a becomes an elliptical short axis, and the inclined lower end portion 210a of one steel plate 200a is shown in FIGS. 10 (c) and 11 (c). ), A line segment F connecting a central portion 230a that is rotated 90 ° counterclockwise and a central portion 230b that is rotated 90 ° counterclockwise from the inclined lower end portion 210b of the other steel plate 200b. Is the major axis of the ellipse.

  Therefore, when this screw-in type steel pipe pile is rotated around the central axis L of the steel pipe 100 and penetrated into the ground, the region extending from the inclined lower end portion 210a to the central portion 230a of the steel plate 200a and the inclination of the steel plate 200b There is a possibility that the region from the lower end portion 210b to the central portion 230b comes into contact with the ground and the outer peripheral portions of the steel plates 200a and 200b are worn over the entire surface. If the amount of wear increases as a result of such wear, the area and thickness of each steel plate 200a, 200b will be reduced, and as a result, it may be difficult to obtain good ground support. there were.

  In order to solve the above problem, when the center axis L of the steel pipe 100 is arranged so as to be orthogonal to the ground, the steel plate 200a so that the projected shape of the steel plates 200a, 200b on the ground is a circle. , 200b can be adjusted. However, since the projection shape easily changes depending on the inclination angle of the steel plates 200a, 200b with respect to the direction orthogonal to the axial direction of the steel pipe 100, the steel plate 200a, It is necessary to change the shape of 200b as appropriate, and the manufacture of the screw-in type steel pipe pile is complicated and not practical.

  10 and 11 show examples in which the extension lengths and the inclination angles of the tip surfaces of the two attachment portions 120a and 120b are equal to each other, but even when the inclination angles of the attachment portions 120a and 120b are different, That is, it goes without saying that the same problem occurs even if the steel plates 200a and 200b attached to the attachment portions 120a and 120b have different inclination angles.

  An object of this invention is to provide the screwed-type steel pipe pile which can reduce the abrasion amount of steel plates and can obtain favorable ground supporting force in view of the said situation.

The screwed steel pipe pile according to the present invention is a direction in which a plurality of steel plates formed by dividing a circular steel plate having a larger outer diameter than a cylindrical steel pipe into a substantially fan shape is orthogonal to the central axis of the steel pipe Is a screwed-type steel pipe pile that is attached along the circumferential direction of the steel pipe in a manner that inclines with respect to the hollow portion of the steel pipe, and the central axis of the steel pipe is perpendicular to the ground. Rotate around the central axis of the steel pipe at the most distal end of the plurality of steel plates that is the portion with the smallest radial length among the projected shapes formed on the ground by arranging comprising a sacrificial member arranged to project radially outside than the steel plate length of most radial direction with the location to approach the locus of the larger portion of its trajectory the projected shape If It is a thing.

  Here, “obstructing the hollow portion of the steel pipe” means that the hollow portion is substantially blocked by a plurality of steel plates when the hollow portion is viewed from the tip side of the steel pipe along the axial direction of the steel pipe. More specifically, it means that an opening for taking earth and sand or the like is not formed in the central region of a plurality of steel plates as disclosed in Japanese Patent Application Laid-Open No. 2009-209654.

  Further, the present invention provides the above threaded steel pipe pile, wherein a plurality of the steel pipes are formed along the circumferential direction at the tip of the steel pipe, and each tip surface is gradually inclined toward the tip side from one side to the other side in the circumferential direction. The steel plate is attached along the front end surface of the corresponding attachment portion.

  In the screwed steel pipe pile according to the present invention, a ratio of a length of the sacrificial member projecting outward in a radial direction to an outer diameter of the circular steel plate is 0.05 or less.

  According to the present invention, since the sacrificial member is arranged in a manner that protrudes more radially outward than the steel plate having the location at the most distal end among the plurality of steel plates, the sacrificial member is It is possible to reduce the rate at which the outer peripheral portion of the steel plate is worn by being in contact with the ground. As a result, when a screwed steel pipe pile is buried in the ground, the amount of wear of the steel plate is reduced, and the steel plate has a sufficient area and thickness, thereby supporting a large ground support as a support. You can gain power. Therefore, there is an effect that the wear amount of the steel plate can be reduced and a good ground supporting force can be obtained.

(A) of FIG. 1 is a front view of the principal part of the screwed-type steel pipe pile which is Embodiment 1 of this invention. FIG. 1B is a plan view of the threaded steel pipe pile of FIG. (C) of FIG. 1 is explanatory drawing which shows the projection shape of this screwed-type steel pipe pile when arrange | positioning the screwed-type steel pipe pile of (a) and (b) so that the center axis | shaft of a steel pipe may be orthogonal to the ground. (A) of FIG. 2 is a right view of the principal part of the screwed-type steel pipe pile which is Embodiment 1 of this invention. FIG. 2B is a plan view of the screwed steel pipe pile of FIG. (C) of FIG. 2 is explanatory drawing which shows the projection shape of this screwed-type steel pipe pile when arrange | positioning the screwed-type steel pipe pile of (a) and (b) so that the center axis | shaft of a steel pipe may be orthogonal to the ground. FIG. 3 is a perspective view showing the tip of the steel pipe shown in FIGS. 1 and 2. FIG. 4 is an explanatory view schematically showing a construction example of the screwed steel pipe pile shown in FIGS. 1 and 2. (A) of FIG. 5-1 is a front view of the principal part of the screwed-type steel pipe pile which is Embodiment 2 of this invention. FIG. 5B is a plan view of the threaded steel pipe pile of FIG. (C) of FIG. 5-1 is explanatory drawing which shows the projection shape of this screwed-type steel pipe pile when arrange | positioning the screwed-type steel pipe pile of (a) and (b) so that the center axis | shaft of a steel pipe may be orthogonal to the ground. is there. 5-2 is a top view which shows the modification of the screwed-type steel pipe pile which is Embodiment 2 of this invention. (A) of FIG. 6 is a front view of the principal part of the screwed-type steel pipe pile which is Embodiment 3 of this invention. FIG. 6B is a plan view of the threaded steel pipe pile of FIG. (A) of FIG. 7 is a front view of the principal part of the screwed-type steel pipe pile which is Embodiment 4 of this invention. (B) of Drawing 7 is a top view of the screwed-type steel pipe pile of (a). FIG. 8 is an enlarged side view showing a main part of a modified example of the screw-in type steel pipe pile according to the first embodiment of the present invention. FIG. 9 is an enlarged side view showing an enlarged main part of another modification of the screw-in type steel pipe pile according to Embodiment 1 of the present invention. (A) of FIG. 10 is a front view of the principal part of the conventional screwed-type steel pipe pile. (B) of FIG. 10 is a plan view of the screwed steel pipe pile of (a). (C) of FIG. 10 is explanatory drawing which shows the projection shape of this screwed-type steel pipe pile when arrange | positioning the screwed-type steel pipe pile of (a) and (b) so that the center axis | shaft of a steel pipe may be orthogonal to the ground. (A) of FIG. 11 is a right view of the principal part of the conventional screwed-type steel pipe pile. FIG. 11B is a plan view of the screw-in type steel pipe pile of FIG. (C) of FIG. 11 is explanatory drawing which shows the projection shape of this screwed-type steel pipe pile when arrange | positioning the screwed-type steel pipe pile of (a) and (b) so that the center axis | shaft of a steel pipe may be orthogonal to the ground.

  Exemplary embodiments of a threaded steel pipe pile according to the present invention will be described below in detail with reference to the accompanying drawings.

<Embodiment 1>
1 and 2 each show an example of a screw-in type steel pipe pile according to Embodiment 1 of the present invention. (A) of FIG. 1 is a front view of the principal part of a screwed-type steel pipe pile, FIG.1 (b) is a top view of the screwed-type steel pipe pile of (a) of FIG. FIG. 2A is a right side view of the main part of the screw-type steel pipe pile, and FIG. 2B is a plan view of the screw-type steel pipe pile of FIG. The screwed steel pipe pile illustrated here includes a steel pipe 10 and a plurality (two in the illustrated example) of steel plates 20a and 20b. In addition, in the screwed-type steel pipe pile shown in these FIG.1 and FIG.2, a front end side is demonstrated as a downward direction, and the pile head side is demonstrated as an upper direction.

  The steel pipe 10 has a cylindrical shape having a hollow portion 11 inside. As shown in FIG. 3, a plurality of (two in the illustrated example) attachment portions 12 a and 12 b are formed at the tip of the steel pipe 10. In FIG. 3, the tip side is shown upward and the pile head side is shown downward so that the attachment portions 12 a and 12 b can be easily shown.

  These attachment portions 12a and 12b are formed along the circumferential direction of the tip portion by dividing the tip portion of the steel pipe 10 into two equal parts in the circumferential direction. More specifically, the attachment portion 12a is adjacent to the other attachment portion 12b via the step portions 13a and 13b, and the respective front end surfaces 12a1 and 12b1 are directed from one to the other in the circumferential direction. Inclined gradually upward. That is, the tip surface 12a1 of one mounting portion 12a is formed to be inclined so as to continue from the lower end of one step portion 13a to the upper end of the other step portion 13b, and the tip surface 12b1 of the other mounting portion 12b is Further, the second step portion 13b is formed so as to be inclined from the lower end of the other step portion 13b to the upper end of the one step portion 13a.

  Here, the height h of the stepped portions 13a and 13b is the state of the ground G (see FIG. 4) in which the screwed steel pipe pile is embedded, the outer diameter of the steel pipe 10 (hereinafter also referred to as the pile diameter), and the steel plates 20a and 20b. The ratio to the pile diameter is preferably about 0.1 to 0.5.

  Note that the two attachment portions 12a and 12b exemplified here have the extension lengths of the tip surfaces 12a1 and 12b1 and the inclination angles of the tip surfaces 12a1 and 12b1 equal to each other.

  The steel plates 20a and 20b are each formed by dividing a circular steel plate having an outer diameter larger than that of the steel pipe 10 into two parts, and have a semicircular shape. Here, the outer diameter (hereinafter also referred to as blade diameter) of the circular steel plate is appropriately determined depending on the state of the ground G in which the screwed steel pipe pile is embedded, the outer diameter of the steel pipe 10, the number of steel plates 20a and 20b, and the like. In addition, as the material of the circular steel plate, a material having strength equivalent to that of SM490 material or SM570 material is used, and the thickness (plate thickness) is about 10 to 100 mm.

  One steel plate 20a is attached to the direction perpendicular to the axial direction of the steel pipe 10 by being attached by welding or the like along the distal end surface 12a1 of the one attachment portion 12a. The outer peripheral portion of the steel plate 20a protrudes toward the outside in the radial direction of the steel pipe 10 as shown in FIG. 1 (b) and FIG. 2 (b). Moreover, in this steel plate 20a, the inclination lower end part 21a and the inclination upper end part 22a are formed by inclining and attaching with respect to the direction orthogonal to the axial direction of the steel pipe 10. As shown in FIG.

  The other steel plate 20b is attached so as to be inclined with respect to the direction perpendicular to the axial direction of the steel pipe 10 by being attached by welding or the like along the distal end surface 12b1 of the other attachment portion 12b. The outer peripheral portion of the steel plate 20b protrudes outward in the radial direction of the steel pipe 10 as shown in FIG. 1B and FIG. 2B. Moreover, in this steel plate 20b, the inclination lower end part 21b and the inclination upper end part 22b are formed by inclining and attaching with respect to the direction orthogonal to the axial direction of the steel pipe 10. As shown in FIG.

  As described above, the two attachment portions 12a and 12b have the same extension length and inclination angle of the end faces 12a1 and 12b1, and therefore the steel plate 20a attached to each attachment portion 12a and 12b. , 20b are equal to each other. Thus, the inclined lower end 21a and the inclined lower end 21b are the lowest positions of the two steel plates 20a and 20b, and the inclined upper end 22a and the inclined upper end 22b are the two steel plates 20a. , 20b is the uppermost portion.

  In such a screwed steel pipe pile, the ratio of the blade diameter to the pile diameter is, for example, 1.5 to 3.

  Reference numeral 14 in FIG. 1 is a closing member. The closing member 14 is, for example, a plate-like body having a triangular shape, and closes a portion that opens laterally at the distal end portion of the steel pipe 10 by forming the step portions 13a and 13b. In the first embodiment, it is closed by the closing member 14, but in the present invention, such a portion does not have to be closed. This is because earth and sand do not enter the inside of the steel pipe because the opening area of the portion is small. However, the strength of the screwed steel pipe pile can be improved by closing the portion with the closing member 14 as in the first embodiment.

  In such a screw-type steel pipe pile, since the steel plates 20a and 20b are formed by dividing a circular steel plate, as shown in FIG. 1 (b) and FIG. 2 (b), The opening at the tip of the steel pipe 10 is substantially closed by the steel plates 20a and 20b, and has a closed end structure in which no opening for taking in earth and sand is formed in the central region of the steel plates 20a and 20b.

  In the screwed steel pipe pile, since the steel plates 20a and 20b are attached to the direction perpendicular to the axial direction of the steel pipe 10, the central axis L of the steel pipe 10 is orthogonal to the ground. In this arrangement, as shown in FIG. 1C and FIG. 2C, the projection shapes of the steel plates 20a and 20b on the ground become an ellipse. In this case, a line segment A connecting the inclined lower end portions 21a, 21b and the inclined upper end portions 22a, 22b becomes an elliptical short axis, and from the inclined lower end portion 21a of one steel plate 20a, FIG. 2 (c), a central portion 23a that is rotated 90 ° counterclockwise, and a central portion 23b that is rotated 90 ° counterclockwise from the inclined lower end portion 21b of the other steel plate 20b. The connecting line segment B is the major axis of the ellipse.

  In the steel plates 20a and 20b, the sacrificial members 25 are attached to the lower surfaces of the lowermost inclined lower end portions 21a and 21b by welding or the like. These sacrificial members 25 are constituted by, for example, excavating blades, and are rectangular when viewed from above or from the front as shown in FIG. 1, and parallel when viewed from the right as shown in FIG. It is a rectangular parallelepiped with a quadrilateral shape. The material of these sacrificial members 25 is not particularly limited, and the strength is appropriately selected according to the strength of the ground to be excavated.

  These sacrificial members 25 are attached at the corresponding inclined lower end portions 21a and 21b so as to protrude more radially outward than the steel plates 20a and 20b having the inclined lower end portions 21a and 21b. Here, the protruding length (projecting length) of the sacrificial member 25 from the steel plates 20a and 20b is such that the ratio of the length of the sacrificial member 25 protruding outward in the radial direction to the blade diameter is 0.05 or less. Is preferred. Since the ratio of the projecting length of the sacrificial member 25 in the radial direction to the blade diameter is in such a range, the trajectory of the sacrificial member 25 due to the rotation of the screwed steel pipe pile around the central axis of the steel pipe 10 is the above-mentioned length. It can be brought close to the locus of the central portion 23a forming the axis.

  Here, specific examples of dimensions are shown. The outer diameter of the steel pipe 10 is 1000 mm, the inclination of the steel plates 20a and 20b is 14.4 °, the major axis of the projected shape (ellipse) is 2000 mm, and the minor axis is 1937 mm. In this case, it is desirable to adjust the length of the sacrificial member 25 protruding outward in the radial direction to 31.5 mm.

  A construction example using the screwed steel pipe pile having the above configuration will be described with reference to FIG. As shown to (a) of FIG. 4, a rotational force is provided and it rotates around the central axis L of the steel pipe 10, and a screwed-type steel pipe pile is grounded to the ground g. In this case, in one steel plate 20a, the inclined lower end portion 21a is a portion that first penetrates into the ground G, and in the other steel plate 20b, the inclined lower end portion 21b is a portion that first penetrates into the ground G. . And since these two inclination lower end parts 21a and 21b are the parts located in the lowest part in the two steel plates 20a and 20b, the start end which penetrates into the ground G first in the two steel plates 20a and 20b. Part.

  Next, as shown in FIG. 4B, the screwed steel pipe pile is screwed into the ground G by the action of the screws at the protruding portions of the two steel plates 20a, 20b. In this case, the sacrificial member 25 has its own trajectory by rotating around the central axis L of the steel pipe 10 substantially coincides with the trajectories of the central portions 23a and 23b. The sacrificial member 25 reduces the amount of wear of the steel plates 20a and 20b by reducing the rate at which the outer peripheral portions of the steel plates 20a and 20b wear even if they are in contact with the ground G.

  As a result, as shown in FIG. 4 (c), when the screwed steel pipe pile is embedded in the ground G, the wear amount of the steel plates 20a and 20b is reduced, and the steel plates 20a and 20b are It has a sufficient area and plate thickness, whereby a large ground support force can be obtained as a support.

  Therefore, according to the screw-type steel pipe pile which is Embodiment 1 of this invention, the abrasion loss of steel board 20a, 20b can be reduced, and a favorable ground supporting force can be obtained.

  Moreover, according to the said screwed-type steel pipe pile, the sacrificial member 25 is in the radial direction outside of the steel plates 20a, 20b to the inclined lower end portions 21a, 21b which are the lowermost (tip) in the two steel plates 20a, 20b. Since it is attached so that it protrudes, it is rotated around the central axis L of the steel pipe 10 and screwed into the ground G, and then reversely rotated and pulled out, and then rotated forward again. Even if the construction is screwed into the ground G, the formation of a gap between the inclined lower end portions 21a, 21b of the steel plates 20a, 20b and the ground G is suppressed, and the straightness and stability are excellent. Construction can be carried out.

  Furthermore, according to the screwed steel pipe pile, since the sacrificial member 25 is merely disposed on the inclined lower end portions 21a and 21b, compared with adjusting the shape of the steel plate so that the projected shape of the steel plate is a circle. Thus, it is possible to easily manufacture the screw-type steel pipe pile.

<Embodiment 2>
FIG. 5-1 shows an example of a screw-in type steel pipe pile which is Embodiment 2 of the present invention. FIG. 5A is a front view of the main part of the screwed steel pipe pile, and FIG. 5B is a plan view of the screwed steel pipe pile. In addition, in the screwed-type steel pipe pile shown to this FIG. 5-1, the front end side is demonstrated as a downward direction, and the pile head side is demonstrated as an upper direction.

  The screwed steel pipe pile illustrated here includes a steel pipe 30 and a plurality (two in the illustrated example) of steel plates 40a and 40b.

  The steel pipe 30 has a cylindrical shape having a hollow portion 31 inside. A plurality of (two in the illustrated example) attachment portions 32 a and 32 b are formed at the tip of the steel pipe 30. These attachment portions 32a and 32b are formed along the circumferential direction of the tip portion by dividing the tip portion of the steel pipe 30 into two equal parts in the circumferential direction.

  More specifically, the attachment portion 32a is formed in such a manner that the front end surface 32a1 is gradually inclined upward from one end portion on one side in the circumferential direction toward the other end portion on the other side in the circumferential direction. Has been. Further, the attachment portion 32b is formed in such a manner that a tip surface (not shown) is gradually inclined upward from one end portion on one side in the circumferential direction toward the other end portion on the other side in the circumferential direction. Yes. In these attachment portions 32a and 32b, the other end portion of the attachment portion 32a and one end portion of the attachment portion 32b are continuous, and one end portion of the attachment portion 32a and the other end portion of the attachment portion 32b are stepped portions 33a. Is continuous through. In other words, the mounting portion 32a and the mounting portion 32b are apparently integrated, and the tip end surface 32a1 of the mounting portion 32a is formed so as to be inclined from the lower end of the step portion 33a to one end portion of the mounting portion 32b. The tip end surface of the attachment portion 32b is inclined so as to continue from the other end portion of the attachment portion 32a to the upper end of the step portion 33a. In the second embodiment, the inclination angle of the distal end surface 32a1 of the attachment portion 32a is substantially equal to the inclination angle of the distal end surface of the attachment portion 32b. However, in the present invention, the inclination angle is different. May be.

  Each of the steel plates 40a and 40b is formed by dividing a circular steel plate having an outer diameter larger than that of the steel pipe 30, and has a semicircular shape. Here, the outer diameter of the circular steel plate (hereinafter also referred to as blade diameter) is the state of the ground in which the screwed steel pipe pile is embedded, the outer diameter of the steel pipe 30 (hereinafter also referred to as pile diameter), and the steel plates 40a and 40b. It is determined appropriately depending on the number. In addition, as the material of the circular steel plate, a material having strength equivalent to that of SM490 material or SM570 material is used, and the thickness (plate thickness) is about 10 to 100 mm.

  One steel plate 40a is attached by being inclined along the tip surface 32a1 of one attachment portion 32a by welding or the like, so that the steel plate 40a is inclined with respect to the direction orthogonal to the axial direction of the steel pipe 30. The outer peripheral portion of the steel plate 40a protrudes toward the outside in the radial direction of the steel pipe 30 as shown in FIG. Moreover, in this steel plate 40a, the inclination lower end part 41a and the inclination upper end part 42a are formed by inclining and attaching with respect to the direction orthogonal to the axial direction of the steel pipe 30. As shown in FIG.

  The other steel plate 40b is attached by inclining with respect to the direction orthogonal to the axial direction of the steel pipe 30 by being attached by welding or the like along the distal end surface of the other attachment portion 32b. The outer peripheral portion of the steel plate 40b protrudes toward the outside in the radial direction of the steel pipe 30 as shown in FIG. Moreover, in this steel plate 40b, the inclination lower end part 41b and the inclination upper end part 42b are formed by inclining and attaching with respect to the direction orthogonal to the axial direction of the steel pipe 30. As shown in FIG.

  As described above, the other end portion of the attachment portion 32a and one end portion of the attachment portion 32b are continuous, and one end portion of the attachment portion 32a and the other end portion of the attachment portion 32b are continuous via the step portion 33a. Therefore, the two steel plates 40a and 40b intersect each other at a portion below the outer peripheral portion of the steel pipe 30, that is, at a portion where the other end portion of the attachment portion 32a and one end portion of the attachment portion 32b are continuous. It is arranged. In addition, since the two steel plates 40a and 40b intersect each other below a part of the outer peripheral portion of the steel pipe 30 as described above, the intersecting portion is larger than the separation distance from the intersecting portion to the inclined lower end portion 41b. The distance from the lower end portion 41a to the inclined lower end portion 41a is longer, so that the lower end portion 41a of the steel plate 40a is located below the lower end portion 41b of the steel plate, and the two steel plates 40a and 40b are made of steel. The inclined lower end portion 41a of the plate 40a is the portion located at the lowest position.

  In such a screwed steel pipe pile, the ratio of the blade diameter to the pile diameter is, for example, 1.5 to 3.

  Moreover, also in the said screwed-type steel pipe pile, the part (not shown) opened to the side in the front-end | tip part of the steel pipe 30 is formed by forming the step part 33a similarly to Embodiment 1 mentioned above. Such a portion is closed by a closing member (not shown). In the second embodiment, the portion that opens laterally at the tip of the steel pipe 30 is closed by a closing member (not shown). However, in the present invention, such a portion may not be closed. This is because earth and sand do not enter the inside of the steel pipe because the opening area of the portion is small. However, the strength of the screwed steel pipe pile can be improved by closing the portion with a closing member as in the second embodiment.

  And in such a screwed-type steel pipe pile, since steel plates 40a and 40b are constituted by dividing a circular steel plate, as shown in FIG. The front end opening is substantially closed by the steel plates 40a and 40b, and has a closed end structure in which no opening for taking in earth and sand is formed in the central region of the steel plates 40a and 40b.

  In the screwed steel pipe pile, since the steel plates 40a and 40b are respectively attached to the direction orthogonal to the axial direction of the steel pipe 30, the central axis L of the steel pipe 30 is orthogonal to the ground. In such a case, as shown in FIG. 5C, the projected shape of the steel plates 40a and 40b on the ground becomes an ellipse. In such a projected shape, a line segment C passing through the inclined lower end portion 41a of one steel plate 40a and the central axis L of the steel pipe 30 has the shortest diameter (hereinafter also referred to as a short diameter), and the inclination of the one steel plate 40a. A central portion 44a which is a position rotated 90 ° clockwise in FIG. 5C from the upper end portion 42a, and a position rotated 90 ° counterclockwise from the inclined lower end portion 41b of the other steel plate 40b, The line segment D connecting the central portion 44b is the longest diameter (also referred to as the long diameter).

  In the steel plates 40a and 40b, a sacrificial member 45 is attached to the lower surface of the lowermost inclined lower end portion 41a by welding or the like. These sacrificial members 45 are constituted by, for example, excavation blades or the like. The material of the sacrificial member 45 is not particularly limited, and the strength is appropriately selected according to the strength of the ground to be excavated.

  The sacrificial member 45 is attached at the inclined lower end portion 41a so as to protrude outward in the radial direction from the steel plate 40a having the inclined lower end portion 41a. Here, as for the protrusion length (projecting length) of the sacrificial member 45 from the steel plate 40a, the ratio of the length of the sacrificial member 45 protruding outward in the radial direction with respect to the blade diameter is preferably 0.05 or less. . Since the ratio of the protrusion length of the sacrificial member 45 in the radial direction to the blade diameter is in such a range, the trajectory of the sacrificial member 45 caused by the screw-type steel pipe pile rotating around the central axis L of the steel pipe 30 is the above. It is possible to approach the locus of the central portions 44a and 44b that form the major axis.

  When a rotational force is applied to the screw-type steel pipe pile having the above-described configuration to rotate around the central axis L of the steel pipe 30 and contact with the ground, the inclined lower end 41a first penetrates the ground in one steel plate 40a. In the other steel plate 40b, the inclined lower end portion 41b is a portion that first penetrates into the ground, but the inclined lower end portion 41a of the one steel plate 40a has two steel plates 40a, 40b. Since this is the part located at the lowest position in Fig. 1, it is the starting end that first penetrates into the ground.

  When the screwed steel pipe pile is screwed into the ground by the action of the protruding portions of the two steel plates 40 a and 40 b, the sacrificial member 45 is rotated by rotating around the central axis L of the steel pipe 30. The trajectory substantially coincides with the trajectories of the central portions 44a and 44b. The sacrificial member 45 reduces the amount of wear of the steel plates 40a, 40b by reducing the rate at which the outer peripheral portions of the steel plates 40a, 40b wear due to contact with the ground.

  As a result, when the screwed steel pipe pile is buried in the ground, the amount of wear of the steel plates 40a, 40b is reduced, and the steel plates 40a, 40b have a sufficient area and plate thickness. A large ground supporting force can be obtained as a support.

  Therefore, according to the screwed-type steel pipe pile which is Embodiment 2 of this invention, the abrasion loss of steel board 40a, 40b can be reduced, and a favorable ground supporting force can be obtained.

  Moreover, according to the said screwed-type steel pipe pile, the sacrificial member 45 is attached so that it may protrude outside the radial direction of the steel plate 40a to the inclination lower end part 41a which becomes the lowest (tip) in the two steel plates 40a and 40b. Therefore, as is done for hard ground, it is rotated forward around the central axis L of the steel pipe 30 and screwed into the ground, then once rotated reversely and pulled out, and rotated forward again and screwed into the ground. Even if construction is performed, it is possible to suppress the formation of a gap between the inclined lower end portion 41a of the steel plate 40a and the ground, and it is possible to perform construction excellent in straightness and stability.

  Furthermore, according to the screwed steel pipe pile, since the sacrificial member 45 is merely disposed on the inclined lower end portion 41a, compared to adjusting the shape of the steel plate so that the projected shape of the steel plate is a circle, Manufacture of a screw-in type steel pipe pile can be made easy.

  5-2 is a top view which shows the modification of the screwed-type steel pipe pile which is Embodiment 2 of this invention. In the screwed steel pipe pile according to the second embodiment described above, the steel plate 40a has a semicircular shape. In the present invention, as shown in FIG. The plate making 40 a ′ may have a shape in which a part of the outer diameter of the steel pipe 30 is cut out. In such a steel plate 40a ', the sacrificial member 45 is attached to the inclined lower end portion 41a' so as to protrude outward in the radial direction of the steel plate 40a '.

  In Embodiment 1 and 2 mentioned above, although the screwed-type steel pipe pile provided with two steel plates 20a, 20b, 40a, 40b was demonstrated, the screwed-type steel pipe pile of this invention has two steel plates. It is not restricted to one, It may be a screwed-type steel pipe pile provided with three steel plates, and a screwed-type steel pipe pile provided with four steel plates. This will be described below.

<Embodiment 3>
FIG. 6 shows an example of a screw-in type steel pipe pile according to Embodiment 3 of the present invention. (A) of FIG. 6 is a front view of the principal part of a screwed-type steel pipe pile, and (b) of FIG. 6 is a top view of the screwed-type steel pipe pile. The screwed steel pipe pile illustrated here includes a steel pipe 50 and three steel plates 60a, 60b and 60c. In addition, in the screwed-type steel pipe pile shown in this FIG. 6, the front end side is demonstrated as downward and the pile head side is demonstrated as upper.

  The steel pipe 50 has a cylindrical shape having a hollow portion 51 inside. Three attachment portions 52a, 52b, and 52c are formed at the tip of the steel pipe 50.

  These attachment portions 52a, 52b, and 52c are formed along the circumferential direction of the tip portion by dividing the tip portion of the steel pipe 50 into three equal parts in the circumferential direction. More specifically, the attachment portions 52a, 52b, and 52c are adjacent to the other attachment portions 52a, 52b, and 52c with the stepped portion 53 interposed therebetween, and the front end surfaces of the attachment portions 52a, 52b, and 52c are from one to the other in the circumferential direction. It inclines toward the upper direction gradually toward. Here, the heights of the stepped portions 53 are equal to each other. Note that the three attachment portions 52a, 52b, and 52c illustrated here have the same extension length of the tip surface and the inclination angle of the tip surface.

  The steel plates 60a, 60b and 60c are each formed by dividing a circular steel plate having an outer diameter larger than that of the steel pipe 50 into three parts, and have a fan shape. Here, the outer diameter of the circular steel plate (hereinafter also referred to as blade diameter) is the state of the ground in which the threaded steel pipe pile is embedded, the outer diameter of the steel pipe 50 (hereinafter also referred to as pile diameter), the steel plates 60a, 60b, It is determined appropriately depending on the number of 60c. In addition, as the material of the circular steel plate, a material having strength equivalent to that of SM490 material or SM570 material is used, and the thickness (plate thickness) is about 10 to 100 mm.

  The 1st steel plate 60a is attached by inclining with respect to the direction orthogonal to the axial direction of the steel pipe 50 by attaching by welding etc. along the front end surface of the 1st attaching part 52a. The outer peripheral portion of the first steel plate 60a protrudes toward the outside in the radial direction of the steel pipe 50 as shown in FIG. Moreover, in this 1st steel plate 60a, the inclination lower end part 61a and the inclination upper end part 62a are formed by inclining and attaching with respect to the direction orthogonal to the axial direction of the steel pipe 50. As shown in FIG.

  The 2nd steel plate 60b is attached by inclining with respect to the direction orthogonal to the axial direction of the steel pipe 50 by attaching by welding etc. along the front end surface of the 2nd attachment part 52b. The outer peripheral portion of the second steel plate 60b protrudes outward in the radial direction of the steel pipe 50, as shown in FIG. 6B. Moreover, in this 2nd steel plate 60b, the inclination lower end part 61b and the inclination upper end part 62b are formed by inclining and attaching with respect to the direction orthogonal to the axial direction of the steel pipe 50. As shown in FIG.

  The 3rd steel plate 60c is attached by inclining with respect to the direction orthogonal to the axial direction of the steel pipe 50 by attaching by welding etc. along the front end surface of the 3rd attachment part 52c. The outer peripheral portion of the third steel plate 60c protrudes toward the outside in the radial direction of the steel pipe 50 as shown in FIG. Moreover, in this 3rd steel plate 60c, the inclination lower end part 61c and the inclination upper end part 62c are formed by inclining and attaching with respect to the direction orthogonal to the axial direction of the steel pipe 50. As shown in FIG.

  And as above-mentioned, since the three attaching parts 52a, 52b, and 52c have the same extension length and inclination angle of a front end surface, the steel plate attached to each attaching part 52a, 52b, 52c The inclination angles of 60a, 60b, and 60c are also equal to each other. Thereby, the inclination lower end parts 61a, 61b, 61c become the part located in the lowest part in the three steel plates 60a, 60b, 60c.

  In such a screwed steel pipe pile, the ratio of the blade diameter to the pile diameter is, for example, 1.5 to 3.

  The code | symbol 64 in FIG. 6 is an obstruction | occlusion member. The closing member 64 is, for example, a plate-like body having a triangular shape, and closes a portion that opens laterally at the distal end portion of the steel pipe 50 by forming the stepped portion 53. In the third embodiment, it is closed by the closing member 64. However, in the present invention, such a portion does not have to be closed. This is because earth and sand do not enter the inside of the steel pipe because the opening area of the portion is small. However, the strength of the screw-in type steel pipe pile can be improved by closing the portion with the closing member 64 as in the third embodiment.

  In such a screw-type steel pipe pile, the steel plates 60a, 60b, 60c are formed by dividing a circular steel plate, and therefore, as shown in FIG. However, the steel plates 60a, 60b, and 60c are substantially closed to form a closed end structure in which an opening for taking in earth and sand is not formed in the central region of the steel plates 60a, 60b, and 60c.

  As shown in FIG. 6B, a slight gap is formed between the adjacent steel plates 60a, 60b, 60c. Such gaps may be left as they are, for example, when viewed from above (pile head side) or below (tip side) such that the sum of the internal angles of a plurality of steel plates 60a etc. exceeds 360 ° It is possible to prevent a gap from appearing on the screen.

  In the steel plates 60a, 60b, and 60c, the sacrificial members 65 are attached to the lower surfaces of the lowermost inclined lower end portions 61a, 61b, and 61c by welding or the like. These sacrificial members 65 are constituted by, for example, excavation blades or the like. The material of these sacrificial members 65 is not particularly limited, and the strength is appropriately selected according to the strength of the ground to be excavated.

  These sacrificial members 65 are attached at the corresponding inclined lower end portions 61a, 61b, 61c so as to protrude more radially outward than the steel plates 60a, 60b, 60c having the inclined lower end portions 61a, 61b, 61c. . Here, the protruding length of the sacrificial member 65 from the steel plates 60a, 60b, 60c (projecting length) is such that the ratio of the length of the sacrificial member 65 protruding outward in the radial direction to the blade diameter is 0.05 or less. Preferably there is.

  In the screwed steel pipe pile, since the steel plates 60a, 60b, 60c are respectively attached to the direction orthogonal to the axial direction of the steel pipe 50, the central axis LL of the steel pipe 50 is relative to the ground. In the projected shape formed on the ground when arranged to be orthogonal, the diameter of the shortest line segment passing through the inclined lower end portions 61a, 61b, 61c of the steel plates 60a, 60b, 60c and the central axis L of the steel pipe 50 is Become.

  When a rotational force is applied to the screw-type steel pipe pile having the above-described configuration to rotate around the central axis L of the steel pipe 50 and contact with the ground, the inclined lower end 61a first penetrates the ground in the first steel plate 60a. In the second steel plate 60b, the inclined lower end portion 61b is a portion that first penetrates into the ground, and in the third steel plate 60c, the inclined lower end portion 61c is a portion that first penetrates into the ground. Moreover, since these three inclined lower end portions 61a, 61b, 61c are the lowest positions of the three steel plates 60a, 60b, 60c, the three steel plates 60a, 60b, 60c are in the ground. It becomes the starting end that penetrates first.

  And when the screwed steel pipe pile is screwed into the ground by the action of the screws of the protruding portions of the three steel plates 60a, 60b, 60c, the sacrificial member 65 is rotated around the central axis L of the steel pipe 50. The ratio of the outer peripheral portions of the steel plates 60a, 60b, 60c being worn by being in contact with the ground is reduced. This reduces the amount of wear of the steel plates 60a, 60b, 60c.

  As a result, when the screwed steel pipe pile is embedded in the ground, the wear amount of the steel plates 60a, 60b, 60c is reduced, and the steel plates 60a, 60b, 60c have a sufficient area and thickness. As a result, a large ground supporting force can be obtained as a support.

  Therefore, according to the screwed-type steel pipe pile which is Embodiment 3 of this invention, the abrasion loss of steel board 60a, 60b, 60c can be reduced, and a favorable ground supporting force can be obtained.

  Moreover, according to the said screwed-type steel pipe pile, the sacrificial member 65 is made of steel plates 60a, 60b, 61b, 61c on the inclined lower end portions 61a, 61b, 61c which are the lowermost (tip) in the three steel plates 60a, 60b, 60c. Since it is attached so as to protrude to the outside in the radial direction of 60c, it is rotated around the central axis L of the steel pipe 50 and screwed into the ground, and then reversely rotated and pulled out, as is done for the hard ground. Even if construction is performed such that the steel plate 60a, 60b, 60c is screwed into the ground by forward rotation, it is possible to suppress the formation of gaps between the inclined lower end portions 61a, 61b, 61c of the steel plates 60a, 60b, 60c and the ground. Construction that is excellent in stability and stability can be carried out.

  Furthermore, according to the screwed steel pipe pile, since the sacrificial member 65 is only disposed on the inclined lower end portions 61a, 61b, 61c, the shape of the steel plate is adjusted so that the projected shape of the steel plate is a circle. Compared to the above, it is possible to easily manufacture the screw-type steel pipe pile.

<Embodiment 4>
FIG. 7 shows an example of a screw-in type steel pipe pile according to Embodiment 4 of the present invention. (A) of Drawing 7 is a front view of the important section of a screwed-type steel pipe pile, and (b) of Drawing 7 is a top view of a screwed-type steel pipe pile. The screwed steel pipe pile illustrated here includes a steel pipe 70 and four steel plates 80a, 80b, 80c, and 80d. In addition, in the screwed-type steel pipe pile shown in this FIG. 7, a front end side is demonstrated as downward and a pile head side is demonstrated as upper.

  The steel pipe 70 has a cylindrical shape having a hollow portion 71 inside. Four attachment portions 72 a, 72 b, 72 c, 72 d are formed at the distal end portion of the steel pipe 70.

  These attaching portions 72a, 72b, 72c, 72d are formed along the circumferential direction of the tip portion by dividing the tip portion of the steel pipe 70 into four equal parts in the circumferential direction. More specifically, the attachment portions 72a, 72b, 72c, and 72d are adjacent to each other with the stepped portion 73 interposed therebetween, and the respective front end surfaces gradually move upward from one to the other in the circumferential direction. It is inclined. Here, the height of the stepped portion 73 is assumed to be equal. The four attachment portions 72a, 72b, 72c, and 72d exemplified here have the same extension length of the tip surface and the inclination angle of the tip surface.

  The steel plates 80a, 80b, 80c, and 80d are each formed by dividing a circular steel plate having an outer diameter larger than that of the steel pipe 70 into four parts, and have a fan shape. Here, the outer diameter of the circular steel plate (hereinafter also referred to as blade diameter) is the state of the ground in which the screwed steel pipe pile is embedded, the outer diameter of the steel pipe 70 (hereinafter also referred to as pile diameter), the steel plates 80a, 80b, It is determined appropriately depending on the number of 80c and 80d. In addition, as the material of the circular steel plate, a material having strength equivalent to that of SM490 material or SM570 material is used, and the thickness (plate thickness) is about 10 to 100 mm.

  The 1st steel plate 80a is attached by inclining with respect to the direction orthogonal to the axial direction of the steel pipe 70 by attaching by welding etc. along the front end surface of the 1st attaching part 72a. The outer peripheral portion of the first steel plate 80a protrudes outward in the radial direction of the steel pipe 70 as shown in FIG. Moreover, in this 1st steel plate 80a, the inclination lower end part 81a and the inclination upper end part 82a are formed by inclining and attaching with respect to the direction orthogonal to the axial direction of the steel pipe 70. As shown in FIG.

  The 2nd steel plate 80b is attached by inclining with respect to the direction orthogonal to the axial direction of the steel pipe 70 by attaching by welding etc. along the front end surface of the 2nd attachment part 72b. The outer peripheral portion of the second steel plate 80b protrudes outward in the radial direction of the steel pipe 70 as shown in FIG. 7B. Moreover, in this 2nd steel plate 80b, the inclination lower end part 81b and the inclination upper end part 82b are formed by inclining and attaching with respect to the direction orthogonal to the axial direction of the steel pipe 70. As shown in FIG.

  The 3rd steel plate 80c is attached by inclining with respect to the direction orthogonal to the axial direction of the steel pipe 70 by being attached by welding etc. along the front end surface of the 3rd attachment part 72c. The outer peripheral portion of the third steel plate 80c protrudes outward in the radial direction of the steel pipe 70, as shown in FIG. Moreover, in this 3rd steel plate 80c, the inclination lower end part 81c and the inclination upper end part 82c are formed by inclining and attaching with respect to the direction orthogonal to the axial direction of the steel pipe 70. As shown in FIG.

  The fourth steel plate 80d is attached so as to be inclined with respect to the direction orthogonal to the axial direction of the steel pipe 70 by being attached by welding or the like along the distal end surface of the fourth attachment portion 72d. The outer peripheral portion of the fourth steel plate 80d protrudes toward the outside in the radial direction of the steel pipe 70 as shown in FIG. Moreover, in this 4th steel plate 80d, the inclination lower end part 81d and the inclination upper end part 82d are formed by inclining and attaching with respect to the direction orthogonal to the axial direction of the steel pipe 70. As shown in FIG.

  As described above, the four attachment portions 72a, 72b, 72c, and 72d have the same extension length and inclination angle of the distal end surface, and thus are attached to the respective attachment portions 72a, 72b, 72c, and 72d. The inclination angles of the steel plates 80a, 80b, 80c, and 80d to be obtained are also equal to each other. As a result, the inclined lower end portions 81a, 81b, 81c, 81d are the lowermost portions of the four steel plates 80a, 80b, 80c, 80d.

  In such a screwed steel pipe pile, the ratio of the blade diameter to the pile diameter is, for example, 1.5 to 3.

  In the screwed steel pipe pile, although not shown in the drawing, a portion (not shown) that opens to the side is formed at the tip of the steel pipe 70 by forming the stepped portion 73, and such The portion is closed by a closing member (not shown). In the fourth embodiment, the side opening portion of the steel pipe 70 is closed by a closing member (not shown). However, in the present invention, such a portion may not be closed. This is because earth and sand do not enter the inside of the steel pipe because the opening area of the portion is small. However, the strength of the screw-in type steel pipe pile can be improved by closing the portion with a closing member as in the fourth embodiment.

  And in such a screwed-type steel pipe pile, since steel plates 80a, 80b, 80c, and 80d are constituted by dividing a circular steel plate, as shown in FIG. The closed end structure in which the front end opening of 70 is substantially closed by the steel plates 80a, 80b, 80c, 80d, and no opening for taking in earth and sand is formed in the central region of the steel plates 80a, 80b, 80c, 80d. It has become.

  As shown in FIG. 7B, a slight gap is formed between the adjacent steel plates 80a, 80b, 80c, 80d. Such gaps may be left as they are, for example, when viewed from above (pile head side) or below (tip side) such that the sum of internal angles of a plurality of steel plates 80a etc. exceeds 360 ° It is possible to prevent a gap from appearing on the screen.

  In the steel plates 80a, 80b, 80c, and 80d, the sacrificial members 85 are attached to the lower surfaces of the lowermost inclined lower ends 81a, 81b, 81c, and 81d by welding or the like. These sacrificial members 85 are constituted by, for example, excavation blades or the like. The material of these sacrificial members 85 is not particularly limited, and the strength is appropriately selected according to the strength of the ground to be excavated.

  These sacrificial members 85 project at the corresponding inclined lower end portions 81a, 81b, 81c, 81d to the outside in the radial direction from the steel plates 80a, 80b, 80c, 80d having the inclined lower end portions 81a, 81b, 81c, 81d. It is attached to do. Here, the protruding length (projecting length) of the sacrificial member 85 from the steel plates 80a, 80b, 80c, 80d is such that the ratio of the length of the sacrificial member 85 protruding outward in the radial direction to the blade diameter is 0.05. The following is preferable.

  In the screwed steel pipe pile, the steel plates 80a, 80b, 80c, and 80d are attached with inclination to the direction orthogonal to the axial direction of the steel pipe 70, so that the central axis L of the steel pipe 70 is on the ground. A line passing through the inclined lower end portions 81a, 81b, 81c, 81d of the steel plates 80a, 80b, 80c, 80d and the central axis L of the steel pipe 70 in a projected shape formed on the ground when arranged so as to be orthogonal to each other Minute is the shortest diameter.

  When a rotational force is applied to the screwed steel pipe pile having the above-described configuration to rotate around the central axis L of the steel pipe 70 and contact the ground, the inclined lower end 81a first penetrates the ground in the first steel plate 80a. In the second steel plate 80b, the inclined lower end portion 81b is a portion that first penetrates the ground, and in the third steel plate 80c, the inclined lower end portion 81c is the portion that first penetrates the ground, In the 4-steel plate 80d, the inclined lower end portion 81d is a portion that first penetrates into the ground. In addition, since these four inclined lower end portions 81a, 81b, 81c, 81d are the lowest positions of the four steel plates 80a, 80b, 80c, 80d, the four steel plates 80a, 80b, 80c. , 80d, the first end that first penetrates into the ground.

  And when the screwed steel pipe pile is screwed into the ground by the action of the screws of the protruding portions of the four steel plates 80a, 80b, 80c, 80d, the sacrificial member 85 rotates around the central axis L of the steel pipe 70. This reduces the rate at which the outer peripheries of the steel plates 80a, 80b, 80c, 80d wear due to contact with the ground and wear. This reduces the amount of wear of the steel plates 80a, 80b, 80c, 80d.

  As a result, when the screwed steel pipe pile is embedded in the ground, the amount of wear of the steel plates 80a, 80b, 80c, 80d is reduced, and the steel plates 80a, 80b, 80c, 80d have a sufficient area and It has a plate thickness, so that a large ground supporting force can be obtained as a support.

  Therefore, according to the screw-in type steel pipe pile which is Embodiment 4 of this invention, the abrasion loss of steel board 80a, 80b, 80c, 80d can be reduced, and a favorable ground supporting force can be obtained.

  Moreover, according to the said screwed-type steel pipe pile, the sacrificial member 85 is a steel plate in the inclination lower end part 81a, 81b, 81c, 81d which becomes the lowest (tip) in four steel plates 80a, 80b, 80c, 80d. Since it is attached so as to protrude outward in the radial direction of 80a, 80b, 80c, and 80d, it reverses once after rotating around the central axis L of the steel pipe 70 and screwing it into the ground, as is done for hard ground. Even if construction is performed such that the steel plate 80a, 80b, 80c, 80d is rotated and pulled out and then rotated forward again and screwed into the ground, there is a gap between the inclined lower ends 81a, 81b, 81c, 81d of the steel plates and the ground. It is possible to suppress the formation of, and to perform construction excellent in straightness and stability.

  Furthermore, according to the screwed steel pipe pile, since the sacrificial member 85 is merely disposed on the inclined lower end portions 81a, 81b, 81c, 81d, the shape of the steel plate is adjusted so that the projected shape of the steel plate is a circle. Compared with this, manufacture of a screw-in type steel pipe pile can be made easy.

  As mentioned above, although preferred Embodiment 1-4 of this invention was demonstrated, this invention is not limited to these, A various change can be performed.

  In the first embodiment described above, the sacrificial member 25 is attached to the lower surfaces of the inclined lower end portions 21a and 21b by welding or the like. However, in the present invention, as shown in FIG. The sacrificial member 25 ″ may be attached to the upper surface of the inclined lower end portion 21a by welding or the like, as shown in FIG.

  In the first to fourth embodiments described above, the inclination angles of the front end surfaces 12a1 and the like of the respective attachment portions 12a and the like are assumed to be the same, and the inclination angles of the steel plates 20a and the like attached to the attachment portions 12a and the like are assumed to be equal. In the present invention, the steel plates may be arranged in different modes. In that case, a sacrificial member should just be arrange | positioned in the inclination lower end part located in the front-end | tip most among several steel plates.

  In the first to fourth embodiments described above, the sacrificial member 25 or the like is attached to the inclined lower end portion 21a or the like located at the most distal end among the plurality of steel plates 20a or the like. In the present invention, the sacrificial member is the most distal end. It may be appropriately disposed at a location other than the inclined lower end located at the position as necessary.

  In the first to fourth embodiments described above, the plurality of steel plates 20a and the like are attached to the tip portion of the steel pipe 10 or the like. However, in the present invention, the steel plate is not limited to the tip portion of the steel pipe. It may be provided on the side peripheral surface.

DESCRIPTION OF SYMBOLS 10 Steel pipe 11 Hollow part 12a Attachment part 12b Attachment part 13a Step part 13b Step part 20a Steel plate 21a Inclined lower end part 22a Inclined upper end part 23a Central part 20b Steel plate 21b Inclined lower end part 22b Inclined upper end part 23b Central part 25 Sacrificial member g Ground G Ground L Center axis

Claims (3)

A plurality of steel plates formed by dividing a circular steel plate having an outer diameter larger than that of a cylindrical steel pipe into a substantially fan shape are inclined with respect to a direction perpendicular to the central axis of the steel pipe, and the steel pipe A screw-type steel pipe pile that is attached along the circumferential direction of the steel pipe in a manner that blocks the hollow part,
The most distal end of the plurality of steel plates that is the portion with the smallest radial length among the projected shapes formed on the ground by arranging the central axis of the steel pipe in a posture orthogonal to the ground Where, when rotating around the central axis of the steel pipe, its trajectory is closer to the trajectory of the portion of the projected shape where the length in the radial direction is the largest than the steel plate having the location. screw-steel pipe pile with a sacrificial member arranged to protrude toward the outside. A plurality of attachments are formed along the circumferential direction at the distal end of the steel pipe, and each distal end surface is gradually inclined toward the distal end side from one side to the other in the circumferential direction,
The screw-type steel pipe pile according to claim 1, wherein the steel plates are attached along the front end surfaces of the corresponding attachment portions.   The screwed steel pipe pile according to claim 1 or 2, wherein a ratio of a length of the sacrificial member projecting outward in a radial direction to an outer diameter of the circular steel plate is 0.05 or less.

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