Pile

Abstract

To provide a pile that offers sufficient excavation performance and tip support force.SOLUTION: A pile 100 comprises a pile body 10, wings 20 and 30 provided at the lower end of the pile body 10, and a crushing structure 40 for crushing a ground G provided on bottom surfaces 20a and 30a of the wings 20 and 30.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] This invention relates to a pile having a rotating blade at the tip of the pile body.

Background Art

[0002] Piles constructed in the ground by rotation include, for example, rotary jacked piles and rotary penetrated piles.

[0003] In order to enhance the excavation performance, a rotary jacked pile is provided with a cutting edge at the tip of the pile body. A rotary jacked pile needs to be jacked into the ground to obtain a driving force. Therefore, for the construction of a rotary jacked pile, a pile hammer corresponding to the reaction force from the ground is required.

[0004] In order to obtain a driving force against the ground, a rotary penetrated pile is provided with blades having a larger diameter than the pile body at the tip of the pile body. The blades excavate the ground by rotation and obtain a driving force by pushing up the excavated soil upward. Since a rotary penetrated pile is provided with blades having a larger diameter than the pile body, sufficient supporting force from the ground can be obtained after construction.

[0005] In order to enhance the excavation performance against the ground, some rotary penetrated piles are provided with a cutting edge at the tip of the pile body, similar to the rotary jacked pile. By providing a cutting edge on the rotary penetrated pile, the bottom of the pile hole can be excavated by the cutting edge, so that the soil at the bottom of the pile hole can be broken and softened, and when the tip of the pile body advances in the ground, the resistance applied to the pile body can be weakened.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] However, in the case of a rotary penetration pile equipped with a cutting edge, it is difficult to obtain sufficient tip bearing capacity after construction because the soil at the bottom of the pile hole is softened by the construction.

[0008] An object of the present invention is to provide a pile capable of obtaining sufficient excavation performance and tip bearing capacity.

Means for Solving the Problems

[0009] The pile according to one aspect has a pile body, blades provided at the tip of the pile body, and crushing means provided on the bottom surface of the blades for crushing the ground. According to the pile of this aspect, while crushing the ground by the crushing means provided on the bottom surface of the blades, the pile body can be penetrated into the ground by the rotation of the blades. Therefore, it is possible to provide a pile having sufficient excavation performance and capable of obtaining sufficient tip bearing capacity.

[0010] According to the pile of this aspect, the crushing means may include at least one of a concave portion and a convex portion provided on the bottom surface of the blade, and may include at least one of a plurality of protrusions and depressions provided on the bottom surface. At least one of the plurality of protrusions and depressions may be arranged at the edge of the blade. At least one of the concave portion and the convex portion may be linear. At least one of at least one linear concave portion and at least one linear convex portion may be arranged at the edge of the blade. The protruding height from the bottom surface of the convex portion may be lower than the thickness of the blade or substantially the same height as the thickness of the blade. The protruding height from the bottom surface of the protrusion may be lower than the thickness of the blade or substantially the same height as the thickness of the blade. The crushing means may be provided on the bottom surface of the blade in a region facing the tip of the pile body. The blade is formed by arranging at least two substantially fan-shaped blades side by side in the circumferential direction of the pile body, and the tip of the pile body may be closed by the at least two blades.

Effects of the Invention

[0011] According to the present invention, it is possible to provide a pile capable of obtaining sufficient excavation performance and tip bearing capacity.

Brief Description of the Drawings

[0012]

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MODE FOR CARRYING OUT THE INVENTION

[0013] Hereinafter, embodiments will be described with reference to the drawings. FIG. 1 is a schematic view showing a pile 100 according to an embodiment of the present invention. In the following description, the vertical direction is defined based on an imaginary center line passing through the center of the pile 100.

[0014] The pile 100 has a substantially cylindrical pile body 10 and a rotating blade composed of two substantially semi-circular plates 20 and 30. The pile 100 includes two blades 20 and 30 in a direction intersecting the imaginary center line of the pile body 10 so as to close the lower end side of the pile body 10. The two blades 20 and 30 function as a rotating blade having a substantially circular combined structure. The diameter of the rotating blade is larger than the outer diameter of the pile body 10. The two blades 20 and 30 are provided with a crushing structure (crushing means) on their bottom surfaces 20a and 30a (the illustrated lower surface) for crushing the ground. The illustration of the crushing structure is omitted in FIG. 1. The crushing structure of the blades 20 and 30 will be described later.

[0015] The pile body 10 has a substantially cylindrical blade receiving member 12 and at least one substantially cylindrical connecting member 11. The blade receiving member 12 is a member for attaching the blades 20 and 30. The connecting member 11 is connected to the upper end of the blade receiving member 12 by one or a plurality of members. By changing the number of the connecting members 11, the pile body 10 can be made into a desired length. Note that the blade receiving member 12 and the connecting member 11 may be an integral member. Further, the connecting member 11 may be a steel pipe pile, a concrete pile or an SC pile. The blade receiving member 12 and the connecting member 11 are fixed by welding, bolts or mechanical methods. The blade receiving member 12 and the blades 20 and 30 are fixed by welding or fitting. The structure in which the blades 20 and 30 are fixed to the blade receiving member 12 is the assembly 1.

[0016] FIG. 2 is a bottom view of the assembly 1 as viewed from the direction of the arrow F2 in FIG. 1. FIG. 3 is a side view of the assembly 1 as viewed from the direction of the arrow F3 in FIG. 1. FIG. 4(a) is a view of one blade 30 of the assembly 1 as viewed from the same direction as in FIG. 2, and FIG. 4(b) is a view of the blade 30 in FIG. 4(a) as viewed from the direction of the arrow F4b. FIG. 5(a) is a view of the blade receiving member 12 of the assembly 1 in FIG. 1 as viewed from the same direction as in FIG. 1, FIG. 5(b) is a view of the blade receiving member 12 in FIG. 5(a) as viewed from the direction of the arrow F5b, and FIG. 5(c) is a view of the blade receiving member 12 in FIG. 5(a) as viewed from the direction of the arrow F5c. In FIGS. 1 to 3, the direction parallel to the overhead center line of the pile body 10 is indicated by the Z axis, and the directions orthogonal to the Z axis are indicated by the X axis and the Y axis.

[0017] As shown in FIG. 5, at the lower end of the blade receiving member 12, there are two inclined end faces 14 and 16 that are inclined in different directions at the same angle in the X-axis direction, rather than one annular surface obtained by cutting the blade receiving member 12 in the XY plane orthogonal to its center line. At both circumferential ends of the two inclined end faces 14 and 16, there are axial step portions 15.

[0018] One of the inclined end faces 14 is a face obtained by inclining, at a predetermined angle in the X-axis direction with respect to the XY plane, one of the semi-circular ring-shaped faces that divides the lower end face of the blade receiving member 12 into two in the Y-axis direction. The other inclined end face 16 is a face obtained by inclining, at the same angle in the opposite direction of the X-axis direction with respect to the XY plane, the other semi-circular ring-shaped face that divides the lower end face of the blade receiving member 12 into two in the Y-axis direction. The inclination angle of the inclined end faces 14 and 16 in the X-axis direction with respect to the XY plane is, for example, 5 to 15 degrees, preferably 10 degrees.

[0019] In this embodiment, the case where two inclined end faces 14 and 16 are provided at the lower end of the blade receiving member 12 will be described. However, for example, three or more inclined end faces may be provided at the lower end of the blade receiving member 12. When three or more inclined end faces are provided at the lower end of the blade receiving member 12, the number of blades may be increased according to the number of inclined end faces.

[0020] As shown in FIG. 2, the blades 20 and 30 are formed of a substantially semi-circular flat steel plate and have a point-symmetrical shape. Therefore, here, the structure of one blade 30 will be described, and a detailed description of the other blade 20 will be omitted.

[0021] As shown in FIG. 4, the blade 30 has, along its outer periphery, a linear edge 31 corresponding to the diameter of the semi-circle, an edge 33 corresponding to the arc of the semi-circle continuous with the edge 31 via a corner 32 at one end of the edge 31, and a linear edge 35 continuous with the edge 33 via a corner 34 at one end opposite to the corner 32 of the edge 33. The end of the edge 35 opposite to the corner 34 is connected to the other end of the edge 31 via a corner 36. That is, the blade 30 has a notch 37 in the shape of cutting out a part of the semi-circular steel plate with the edge 35.

[0022] As shown in FIG. 2, the edge portion 35 formed with the notch portion 37 extends by linearly connecting one end 162 (the portion overlapping with the lower end in the inclination direction of the inclined end face 16) of the annular region 161 where the blade 30 overlaps the inclined end face 16 of the blade receiving member 12 and the corner portion 34. The edge portion 35 may be inclined in the direction of the notch portion 37 from the upper surface 30b to the lower surface 30a of the blade 30. In the present embodiment, the notch portion 37 is provided on the lower end side in the inclination direction of the blade 30, but a notch portion may also be provided on the upper end side in the inclination direction. The other blade 20 has three edge portions 21, 22, and 23 of the same shape along its outer periphery and has a notch portion 27 on the lower end side in the inclination direction.

[0023] When fixing the blade 30 to the blade receiving member 12, the center of the semicircle of the blade 30 is aligned with the imaginary center line of the blade receiving member 12, the edge portion 31 of the blade 30 is abutted against the stepped portion 15 of the blade receiving member 12, the upper surface 30b of the blade 30 is brought into contact with the inclined end face 16, and the blade 30 is positioned with respect to the blade receiving member 12. In this state, the outer peripheral surface 12a on the radially outer side of the inclined end face 16 of the blade receiving member 12 and the upper surface 30b of the blade 30 are fixed by welding, and the inner peripheral surface 12b on the radially inner side of the inclined end face 16 of the blade receiving member 12 and the upper surface 30b of the blade 30 are fixed by welding. When welding the inner peripheral surface 12b of the blade receiving member 12 and the upper surface 30b of the blade 30, access is made to the inside of the blade receiving member 12 through the opening 12c at the upper end of the blade receiving member 12.

[0024] After that, the other blade 20 is fixed to the blade receiving member 12. In this case, the center of the semi-circular shape of the blade 20 is aligned with the imaginary center line of the blade receiving member 12, the edge 21 of the blade 20 is abutted against the edge 31 of the blade 30 and the step portion 15 of the blade receiving member 12, the upper surface 20b of the blade 20 is brought into contact with the inclined end surface 14, and the blade 20 is positioned with respect to the blade receiving member 12. In this state, the outer peripheral surface 12a on the radially outer side of the inclined end surface 14 of the blade receiving member 12 and the upper surface 20b of the blade 20 are fixed by welding, the inner peripheral surface 12b on the radially inner side of the inclined end surface 14 of the blade receiving member 12 and the upper surface 20b of the blade 20 are fixed by welding, and the edges 21 and 31 of the blades 20 and 30 that are in contact with each other at the center of the blade receiving member 12 are welded. When welding the inner peripheral surface 12b of the blade receiving member 12 and the upper surface 20b of the blade 20, access is made to the inside of the blade receiving member 12 through the opening 12c of the blade receiving member 12. When a gap is generated between the blade receiving member 12 and the two blades 20 and 30 due to the step portion 15, the gap is filled using a vertical plate or the like. In this way, when the two blades 20 and 30 are fixed to the blade receiving member 12, the lower end side of the blade receiving member 12 is liquid-tightly sealed.

[0025] As described above, when the assembly 1 is assembled, the bottom surface 30a of one blade 30 becomes parallel to one inclined end surface 16 of the blade receiving member 12, and the bottom surface 20a of the other blade 20 becomes parallel to the other inclined end surface 14 of the blade receiving member 12. The pile 100 of the present embodiment can be assembled simply by fixing the two blades 20 and 30 to the blade receiving member 12 and connecting the connecting member 11 to the upper end of the blade receiving member 12. The number of parts is small, the number of working steps is small, the positioning of the members is easy, and it can be easily assembled in a short time. Note that the blades 20 and 30 can be formed simply by shaping a flat steel plate, and bending of the steel plate or the like is not required. If the thickness is adjusted, the mechanical strength can be easily increased.

[0026] Hereinafter, embodiments of the crushing structure provided on the bottom surfaces 20a and 30a of the blades 20 and 30 will be described. In the following description, the blades 20 and 30 are assumed to be in the shape of a semi-circular plate without the cutout portions 27 and 37. That is, the blades 20 and 30 each have a linear edge portion 21 and 31 corresponding to the diameter of the semi-circle, and an edge portion 23 and 33 corresponding to the arc of the semi-circle. The crushing structure of each embodiment may be provided on the blades 20 and 30 having the cutout portions 27 and 37.

[0027] The crushing structures of the respective embodiments described below are all structures such as convex portions, concave portions, protruding portions, and recessed portions provided on the bottom surfaces 20a and 30a of the blades 20 and 30, and their shapes and layouts are variously changed. The crushing structure is for applying an external force to the surface GS of the ground G to generate cracks by the rotation of the pile 100 when the pile 100 is penetrated into the ground G, and for partially destroying the ground G by the propagation of the cracks. The external force applied by the crushing structure to the ground G is, for example, a compressive force, an impact force, a shear force, a frictional force, or the like. In other words, the purpose of the crushing structure is to weaken the resistance force received by the pile 100 from the ground G by rubbing and crushing the ground G, and any structure that can rub and crush the ground G may be used.

[0028] As shown in FIGS. 6 to 8, the crushing structure 40 according to the first embodiment has a plurality of linear protrusion portions 42 protruding from the bottom surfaces 20a and 30a of the two blades 20 and 30. The protruding height of the protrusion portions 42 from the bottom surfaces 20a and 30a is lower than the thickness of the blades 20 and 30, or substantially the same height as the thickness of the blades 20 and 30. The protrusion portion 42 is an example of a linear convex portion. Each protrusion portion 42 has a substantially rectangular cross-sectional shape intersecting its longitudinal direction. The cross-sectional shape of the protrusion portion 42 is not limited to a substantially rectangular shape and may be any shape. For example, the protrusion portion 42 may be formed by welding reinforcing bars to the bottom surfaces 20a and 30a of the blades 20 and 30. Each protrusion portion 42 extends radially from the center of the semi-circle of the blades 20 and 30. The end portions of each protrusion portion 42 spaced apart from the centers of the blades 20 and 30 terminate at arcuate edges 23 and 33. The protrusion portion 44 provided at the edges 21 and 31 corresponding to the diameter of the semi-circle has a length connecting two protrusion portions 42 linearly and extends over the entire length of the edges 21 and 31.

[0029] As shown in FIG. 9, the crushing structure 50 according to the second embodiment is provided with a plurality of linear groove portions 52 instead of the plurality of protrusion portions 42 of the first embodiment described above. The groove portion 52 is an example of a linear concave portion. Each groove portion 52 has a substantially rectangular cross-sectional shape intersecting its longitudinal direction. The cross-sectional shape of the groove portion 52 is not limited to a substantially rectangular shape and may be any shape. Each groove portion 52 extends radially from the center of the semi-circle of the blades 20 and 30. Each groove portion 52 extends from the center of the blades 20 and 30 to the arcuate edges 23 and 33. The end portions of each groove portion 52 spaced apart from the centers of the blades 20 and 30 terminate at arcuate edges 23 and 33. The groove portion 54 provided at the edges 21 and 31 corresponding to the diameter of the semi-circle has a length connecting two groove portions 52 linearly and extends over the entire length of the edges 21 and 31.

[0030] As shown in FIG. 10, the grinding structure 60 according to the third embodiment has a plurality of linear groove portions 62 shorter than the groove portion 52 of the second embodiment described above. The groove portion 62 is an example of a linear concave portion. Each groove portion 62 has a substantially rectangular cross-sectional shape that intersects its longitudinal direction. The cross-sectional shape of the groove portion 62 is not limited to a substantially rectangular shape and may be any shape. Each groove portion 62 extends radially from the center of the semi-circle of the blades 20 and 30. Each groove portion 62 extends to midway toward the arcuate edges 23 and 33 from the center of the blades 20 and 30. The groove portion 64 provided at the edges 21 and 31 corresponding to the diameter of the semi-circle has a length that linearly connects two groove portions 62. The plurality of groove portions 62 may be arranged within a circular region facing the lower end of the blade receiving member 12. As a modification of the third embodiment, a plurality of ridge portions, which are an example of a linear convex portion, may be provided instead of the plurality of groove portions 62.

[0031] As shown in FIGS. 11 and 12, the grinding structure 70 according to the fourth embodiment has a plurality of curved groove portions 72 engraved on the bottom surfaces 20a and 30a of the two blades 20 and 30. The groove portion 72 is an example of a linear concave portion. Each groove portion 72 extends spirally in a vortex shape generally in the radial direction from the center of the semi-circle of the blades 20 and 30. The end portions of each groove portion 72 spaced apart from the centers of the blades 20 and 30 terminate at the arcuate edges 23 and 33. As a modification of the fourth embodiment, a plurality of curved ridge portions, which are an example of a linear convex portion, may be provided instead of the plurality of groove portions 72.

[0032] As shown in FIGS. 13 and 14, the grinding structure 80 according to the fifth embodiment has a plurality of linear protrusion portions 82 protruding from the bottom surfaces 20a and 30a of the two blades 20 and 30. The protrusion portion 82 is an example of a linear convex portion. Each protrusion portion 82 has a substantially rectangular cross-sectional shape that intersects its longitudinal direction. The cross-sectional shape of the protrusion portion 82 is not limited to a substantially rectangular shape and may be any shape. For example, the protrusion portion 82 may be formed by welding reinforcing bars to the bottom surfaces 20a and 30a of the blades 20 and 30. Each protrusion portion 82 extends parallel to the edges 21 and 31 corresponding to the diameters of the semi-circles of the blades 20 and 30. The protrusion portion 82 may extend at an arbitrary angle with respect to the edges 21 and 31, or may extend in a direction perpendicular to the edges 21 and 31. The plurality of protrusion portions 82 are arranged at equal intervals, spaced apart from each other in a direction intersecting their longitudinal direction. The intervals between the respective protrusion portions 82 do not have to be equal. Both ends of each protrusion portion 82 terminate at the arcuate edges 23 and 33 of the blades 20 and 30. FIG. 15 shows a grinding structure 85 according to a modification of the fifth embodiment. The grinding structure 85 has a plurality of groove portions 87, which are an example of linear concave portions, instead of the plurality of protrusion portions 82 of the fifth embodiment.

[0033] As shown in FIGS. 16 to 18, the grinding structure 90 according to the sixth embodiment has a plurality of protrusion portions 92 protruding from the bottom surfaces 20a and 30a of the two blades 20 and 30. The plurality of protrusion portions 92 are uniformly dispersed and arranged on substantially the entire bottom surfaces 20a and 30a of the blades 20 and 30. The size and shape of the protrusion portions 92 may be any. The protruding height of each protrusion portion 92 from the bottom surfaces 20a and 30a is lower than the thickness of the blades 20 and 30, or substantially the same height as the thickness of the blades 20 and 30.

[0034] FIG. 19 shows a crushing structure 95 according to a modification of the sixth embodiment. The crushing structure 95 is formed by arranging a row of protrusions 97 having the same structure as the protrusions 92 of the crushing structure 90 in an arc around the center of the semi-circle of each of the blades 20 and 30. The plurality of protrusions 97 may be arranged within a circular region facing the lower end of the blade receiving member 12. The number and layout of the protrusions 92 and 97 may be any. Further, instead of the protrusions 92 and 97 of the sixth embodiment and its modification, a plurality of recessed portions having the same shape as the protrusion 92 may be provided on the bottom surfaces 20a and 30a of the blades 20 and 30.

[0035] As shown in FIGS. 20 and 21, a crushing structure 110 according to the seventh embodiment has two linear protrusion portions 112 arranged along the edges 21 and 31 corresponding to the diameters of the semi-circles of the blades 20 and 30. The protrusion portion 112 is an example of a linear convex portion. There is one protrusion portion 112 on the bottom surface 20a of the blade 20, and there is one protrusion portion 112 on the bottom surface 30a of the blade 30. Each protrusion portion 112 is provided over the entire length of the edges 21 and 31 of the blades 20 and 30.

[0036] FIG. 22 shows a crushing structure 115 according to a modification of the seventh embodiment. The crushing structure 115 is formed by arranging two protrusion portions 117 having the same cross-sectional shape as the protrusion portion 112 of the crushing structure 110 along the edges 21 and 31 of each of the blades 20 and 30. The protrusion portion 117 is an example of a linear convex portion and is shorter than the protrusion portion 112. The two protrusion portions 117 may be arranged within a circular region facing the lower end of the blade receiving member 12.

[0037] As shown in FIG. 23, a crushing structure 120 according to the eighth embodiment has a plurality of protrusions 122 arranged linearly at equal intervals along the edges 21 and 31 corresponding to the diameters of the semi-circles of the blades 20 and 30. The structure of the protrusions 122 may be any. The protruding height of each protrusion 122 from the bottom surfaces 20a and 30a of the blades 20 and 30 is lower than the thickness of the blades 20 and 30, or substantially the same height as the thickness of the blades 20 and 30.

[0038] FIG. 24 shows a crushing structure 125 according to a modified example of the eighth embodiment. The crushing structure 125 is formed by arranging protrusions 127 having the same structure as the protrusions 122 of the crushing structure 120 along the edges 21 and 31 of the blades 20 and 30. The number of protrusions 127 provided on the edges 21 and 31 of the blades 20 and 30 is smaller than that of the protrusions 122. The plurality of protrusions 127 of the eighth embodiment may be arranged within a circular region facing the lower end of the blade receiving member 12.

[0039] In each of the above-described embodiments, the thickness of the blades 20 and 30 is determined according to the size of the blade diameter so as to withstand the supporting force and the excavation load. Further, when the supporting layer is disturbed by excavation, a pile with a smaller blade diameter is more easily affected. For this reason, by making the height of the convex portions or protrusions provided on the bottom surfaces 20a and 30a of the blades 20 and 30 lower than or substantially the same as the thickness of the blades 20 and 30, it is possible to minimize the disturbance of the supporting layer and apply an excavation force corresponding to the size of the pile. Further, since the circular region facing the lower end of the blade receiving member 12 cannot be excavated by the edges on the lower end side of the blades 20 and 30, providing a crushing structure in this region can achieve the effect of supplementing the excavation of this region.

[0040] Hereinafter, a method for constructing a pile 100 provided with the crushing structure 40 of the first embodiment described above in the ground G will be described as a representative example. When constructing the pile 100 in the ground G, first, the pile 100 is attached to a pile driver or the like, and the lower end of the pile 100 is opposed to the surface GS of the ground G, and the pile 100 is arranged perpendicular to the surface GS of the ground G. In this state, the pile 100 is rotated clockwise toward the ground G and brought into contact with the surface GS of the ground G.

[0041] When the pile 100 is rotated and brought into contact with the surface GS of the ground G, the ground G is excavated by the two blades 20 and 30, and the soil generated by the excavation moves from the bottom surfaces 20a and 30a sides of the blades 20 and 30 through the notch portions 27 and 37 to the upper surface 20b and 30b sides of the blades 20 and 30, and the soil excavated by the inclination of the blades 20 and 30 is pushed upward. Thereby, a propulsive force for the pile 100 to dig into the ground G can be obtained.

[0042] At this time, the protrusion portions 42 protruding from the bottom surfaces 20a and 30a of the two blades 20 and 30 function to apply a predetermined external force to the surface GS of the ground G to crush the ground G. By crushing the ground G, the resistance force received by the blades 20 and 30 of the pile 100 from the ground G can be weakened, and the excavation performance of the ground G can be improved. If a crushing structure such as the protrusion portion 42 is not provided on the bottom surfaces 20a and 30a of the blades 20 and 30, excavation will only be performed at the edges 25 and 35 on the lower end sides of the blades 20 and 30. Therefore, it is expected that excavation of the ground G will be more difficult compared to the case where the protrusion portion 42 is provided.

[0043] The protrusion portions 42 protruding from the bottom surfaces 20a and 30a of the blades 20 and 30 may protrude from the bottom surfaces 20a and 30a of the blades 20 and 30 with a predetermined protruding height, and their shapes and layouts can be of any kind. For example, arc-shaped protrusion portions may be arranged concentrically on the bottom surfaces 20a and 30a of the blades 20 and 30. Also, like in other embodiments, the shapes, sizes, layouts, etc. of the crushing structures such as convex portions, concave portions, protruding portions, and recessed portions provided on the bottom surfaces 20a and 30a of the blades 20 and 30 can be arbitrarily set. The crushing structure may be fixed to the side surfaces of the blades 20 and 30, or may also serve as the crushing structure for a plurality of blades 20 and 30 at the same time. Further, the blade receiving member 12 may be provided with a cutting blade in a region facing the lower end of the blade receiving member 12 in addition to the blades 20 and 30.

[0044] The height of the convex portion and the depth of the concave portion of the crushing structure in each of the above-described embodiments may be constant or variable, and may be parallel or non-parallel to the blades 20 and 30. Also, the height of the protruding portion and the depth of the recessed portion may be the same or different individually. Further, the shapes and sizes of the crushing structures may be different for each of the blades 20 and 30 or for each part of the member.

[0045] As described above, according to the above-described embodiments, due to the rotation of the rotary blades during the construction of the pile 100, the grinding structures 40, 50, 60, 70, 80, 85, 90, 95, 110, 115, 120, 125 provided on the bottom surfaces 20a, 30a of the blades 20, 30 grind the ground G, so that the excavation of the ground G by the blades 20, 30 can be effectively assisted. For example, by crushing the ground G with the grinding structure, the load concentrated at the lower ends of the blades 20, 30 can be dispersed over the entire blades 20, 30. Further, the grinding structures of the respective embodiments are merely the blade structures of the rotary blades 20, 30 and do not collapse the ground G more than necessary during the construction of the pile 100. Therefore, sufficient tip support force can be obtained after the construction of the pile 100.

[0046] Note that the present invention is not limited to the above-described embodiments and their modifications, and various modifications can be made without departing from the gist thereof at the implementation stage. Further, the above-described embodiments and their modifications include various inventions, and various inventions can be extracted by combinations selected from a plurality of disclosed constituent elements. For example, even if some constituent elements are deleted from all the constituent elements shown in the present embodiment and its modifications, and the problem can be solved and the effect can be obtained, the configuration from which these constituent elements are deleted can be extracted as an invention.

Explanation of Reference Numerals

[0047] 1... assembly, 10... pile body, 11... connecting member, 12... blade receiving member, 14, 16... inclined end faces, 15... step portion, 20, 30... blades, 20a, 30a... bottom surfaces, 21, 31... linear edges, 23, 33... arcuate edges, 40, 50, 60, 70, 80, 85, 90, 95, 110, 115, 120, 125... grinding structures, 42, 44, 82, 112, 117... protruding portions, 52, 54, 62, 64, 72, 87... groove portions, 92, 97, 122, 127... protrusions, 100... pile, G... ground, GS... surface.

Claims

1. A pile body, blades provided at the tip of the pile body, and crushing means provided on the bottom surface of the blades for crushing the ground. The pile having the above.

2. The crushing means includes at least one of a concave portion and a convex portion provided on the bottom surface. The pile according to Claim 1.

3. The crushing means includes at least one of a plurality of protrusions and a plurality of depressions provided on the bottom surface. The pile according to Claim 1.

4. At least one of the plurality of protrusions and the plurality of depressions is arranged at the edge of the blade. The pile according to Claim 3.

5. The crushing means includes at least one of at least one linear concave portion and at least one linear convex portion. The pile according to Claim 2.

6. At least one of at least one linear concave portion and at least one linear convex portion is arranged at the edge of the blade. The pile according to Claim 5.

7. The protruding height of the convex portion from the bottom surface is lower than the thickness of the blade or substantially the same as the thickness of the blade. The pile according to Claim 2.

8. The protruding height of the protrusion from the bottom surface is lower than the thickness of the blade or substantially the same as the thickness of the blade. The pile according to Claim 3.

9. The crushing means is provided on the bottom surface of the blade in a region facing the tip of the pile body. The pile according to Claim 1.

10. The blades are formed by arranging at least two substantially fan-shaped blades side by side in the circumferential direction of the pile body, and the tip of the pile body is closed by at least two of the blades, The pile according to any one of claims 1 to 9.

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