Multiblade type steel pipe pile

Abstract

To provide a multiblade type steel pipe pile which has sufficient push-in force and pull-out force, and which has a sufficient support force even with respect to a force applied in the horizontal direction.SOLUTION: A multiblade type steel pipe pile 1 is constituted by: a steel pipe pile 2; a tip blade 3 disposed at a tip of the steel pipe pile 2 and having a first diameter; a large diameter blade 4 arranged further upward than the tip blade 3 and having a second diameter larger than the first diameter; an intermediate blade 5 provided between the tip blade 3 and the large diameter blade 4 and having a third diameter between the first diameter and the second diameter; and an upper blade 6 disposed above the large diameter blade 4 and having a fourth diameter substantially the same as the third diameter. By the tip blade 3, the intermediate blade 5, the large diameter blade 4, and the upper blade 6, a diamond-shaped support part 40 whose diameter reduces toward the vertical direction is constituted.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a rotary penetration steel pipe pile having a multi-wing type steel pipe pile having a plurality of wings at a tip portion of the steel pipe pile. [Background technology]

[0002] Patent Document 1 (Jitsu Miki Hei 6-24420) discloses a multi-wing steel pipe pile having an excavation blade protruding from the lower end of a steel pipe pile body, an internal spiral blade protruding from the inside of the pile tip over approximately one turn, and a number of external spiral blades protruding from the outer circumferential surface of the pile body over approximately the entire length, the external spiral blades having an outer diameter 2 to 3 times the outer diameter of the pile body and a pitch of approximately one quarter of the outer diameter, at equal intervals of a multiple of the pitch of the external spiral blades. Similarly, Patent Document 2 (Jitsu Miki Hei 7-2677) discloses a multi-wing steel pipe pile having a bottom plate formed in an annular shape attached to the lower end and an excavation blade protruding from the outer circumferential surface of a steel pipe pile body, the external spiral blades having an outer diameter 2 to 3 times the outer diameter of the steel pipe pile body and a pitch of approximately one quarter of the outer diameter, at equal intervals of a multiple of the pitch of the spiral blades, at approximately the entire length.

[0003] Patent Document 3 (Japanese Patent No. 2590157) discloses a multi-winged conical steel pipe pile in which a bottom plate and a drilling blade are provided at the lower end of a steel pipe pile body, and a section from the lower end of the pile body that is 0.5 to 2 times the outer diameter of the pile body is a straight pipe section that guides the pile to move in a straight line, and above that, multiple helical blades for screwing in that extend for approximately one turn are provided at intervals of 3 to 4 times the blade diameter, each of which is formed at the same pitch, the lowest helical blade has an outer diameter approximately twice the outer diameter of the pile body, and the diameters of the upper helical blades become larger at a constant rate, and the starting positions of the helical blades are offset from each other in a planar direction by approximately 90°. Furthermore, Patent Document 4 (Japanese Utility Model Application Laid-Open Publication No. 2-26634) discloses a conical multi-blade exchange friction pile in which a bottom plate and a digging blade are provided at the lower end of the main body of a steel pipe pile, and screw-in helical blades that extend over approximately one turn and have a diameter at least twice the outer diameter of the main body of the steel pipe pile are protruded from the outer surface of the main body of the steel pipe pile at approximately equal intervals along its length, with the outer diameters of these spaced-apart helical blades increasing at a constant rate towards the top.

[0004] Patent Document 5 (Japanese Patent No. 3372627) discloses an inverted cone-shaped multi-bladed steel pipe pile in which a bottom plate, an excavation blade, and grout ejection holes are provided at the lower end of the pile body, and screw-in helical blades are provided at approximately equal intervals along the length of the outer periphery of the pile body, extending over approximately one turn and having a diameter at least twice the outer diameter of the pile body, with the outer diameter of these spaced-apart helical blades increasing at a constant rate toward the top. Patent Document 6 (Patent Publication No. 2691831) discloses a conical multi-bladed steel pipe friction pile in which a bottom plate and an excavation blade are provided at the lower end of the main body of a steel pipe pile, and a large number of screw-in helical blades each spanning approximately one turn and having a diameter at least twice the outer diameter of the main body of the steel pipe pile are protruded from the outer surface of the main body of the steel pipe pile at approximately equal intervals along its length, and the outer diameter of each of the helical blades increases successively at a constant rate from the bottom to the top, with their pitch being approximately half the diameter of the main body of the pile, and the spacing between each helical blade is set to a length that is a multiple of the pitch of the helical blades. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Publication number 6-24420 [Patent Document 2] Publication number 7-2677 [Patent Document 3] Patent No. 2590157 [Patent Document 4] Japanese Utility Model Application Publication No. 2-26634 [Patent Document 5] Patent No. 3372627 [Patent Document 6] Patent No. 2691831 Summary of the Invention [Problem to be solved by the invention]

[0006] In conventional construction methods, a single wing is provided at the tip of the steel pipe pile, and the wing serves to provide support. In the case of a single wing, the larger the wing area is, the greater the support capacity can be, but the greater the load on the wing and the base of the steel pipe pile is, so there is a problem in that it is necessary to increase the thickness of the wing and the steel pipe itself.

[0007] For this reason, in the multi-winged steel pipe pile disclosed in Patent Documents 1 and 2 mentioned above, by providing multiple wings of the same shape, the pile can be embedded into the ground stably and easily by the simple method of rotary propulsion, and has great bearing and pull-out force due to the combination of the bearing pressure of the wings, the friction around the pile, the tip blockage effect of the internal spiral wings of the pile, and the bearing and support force of the external spiral wings at the tip. However, the bearing and pull-out force acting on the buried steel pipe pile depends on the area of ​​the wings provided at the lower end of the steel pipe pile, so there is a problem in that even if multiple wings are provided, the effect is not as great as expected.

[0008] For this reason, as disclosed in Patent Documents 3 to 6, it is known that multiple blades are made to have an approximately conical shape with a diameter gradually increasing from the blade located at the tip, thereby providing sufficient bearing capacity even on soft ground.

[0009] However, conventional multi-winged steel pipe piles have the problem that although they can withstand sufficient downward force (push-in force), they are unable to provide sufficient support against upward force (pull-out force) or even horizontal forces.

[0010] Therefore, an object of the present invention is to provide a multi-winged steel pipe pile which has sufficient pushing force and pull-out force, and further has sufficient bearing capacity against forces applied in the horizontal direction. [Means for solving the problem]

[0011] The multi-winged steel pipe pile of the present invention is composed of a steel pipe pile, a tip wing arranged at the tip of the steel pipe pile and having a first diameter, a large diameter wing arranged above the tip wing and having a second diameter larger than the first diameter, an intermediate wing provided between the tip wing and the large diameter wing and having a third diameter between the first diameter and the second diameter, and an upper wing arranged above the large diameter wing and having a fourth diameter approximately equal to the third diameter, and the tip wing, intermediate wing, large diameter wing and upper wing form a support section having a diamond-shaped cross section whose diameter decreases in the vertical direction by connecting the outer peripheries of each wing.

[0012] With the above configuration, when the steel pipe pile is screwed into the pile, a diamond-shaped support portion is formed between the tip wing and the middle wing, between the middle wing and the large diameter wing, and between the large diameter wing and the upper wing due to the adhesion of soil. In this support portion, a lower truncated cone shape is formed between the tip wing and the middle wing, and between the middle wing and the large diameter wing, and an upper truncated cone shape is formed between the large diameter wing and the upper wing due to the adhesion of soil. As a result, the bottom area and side integral of the lower truncated cone shape can be used as the effective area for supporting the tip of the pile, so that the supporting force in the pushing direction can be improved. In addition, the side area of ​​the upper truncated cone shape and the area integral of the upper wing can be used as the effective area for supporting force in the pulling direction, so that the supporting force in the pulling direction can also be improved, and the side integral of the upper and lower truncated cone shapes of the diamond shape can be used as the effective area for horizontal resistance, so that the supporting force in the horizontal direction can also be improved.

[0013] Furthermore, each of the tip wing, the intermediate wing, the large diameter wing and the upper wing has an inner surface that is inclined at a predetermined angle and welded and fixed to the outer circumferential surface of the steel pipe pile, and is composed of a pair of expansion wings that are arranged and fixed opposite each other, and it is desirable that the expansion wings of the tip wing, the intermediate wing, the large diameter wing and the upper wing are arranged so as to form a pseudo-spiral.

[0014] In this way, by making each wing into a pseudo-helical shape, the soil around the steel pipe pile can be consolidated without being disturbed, thereby providing a supporting effect in the pushing and pulling directions.

[0015] Also, it is preferable that the generatrix of the lower truncated cone shape is inclined at approximately 75° with respect to the bottom surface.

[0016] As a result, the angle between the opposing generatrix lines of the lower truncated cone shape is approximately 30°, making the vertical and horizontal force components efficient. Effect of the Invention

[0017] With the above configuration, according to the present invention, by making each blade into a pseudo-spiral shape, it is possible to drive the pile in a state where the soil is less disturbed during penetration, the load in the pull-out direction is distributed by the two blades that make up the upper truncated cone shape, and the load in the compression direction is distributed by the three blades that make up the lower truncated cone shape, and when the pile is screwed in, the soil adheres to the helical blades and the tip of the pile is formed into a shape that is a combination of the upper and lower truncated cone shapes (a so-called diamond-shaped cross section), thereby achieving greater cross-sectional resistance in the vertical and horizontal directions. [Brief description of the drawings]

[0018] [Figure 1] FIG. 1(a) is an overall view of a multi-winged steel pipe pile according to an embodiment of the present invention, and FIG. 1(b) is a bottom view of the multi-winged steel pipe pile according to the embodiment of the present invention. [Diagram 2] FIG. 2 is an enlarged view of a tip portion of a multi-wing steel pipe pile according to an embodiment of the present invention. [Diagram 3] FIG. 2 is an explanatory diagram showing an upper truncated cone shape and a lower truncated cone shape according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] The present invention will now be described with reference to the drawings. EXAMPLES

[0020] As shown in Figures 1 and 2, the multi-winged steel pipe pile 1 of the present invention is composed of a steel pipe pile 2, a tip wing 3 arranged at the tip of the steel pipe pile 2 and having a first diameter, a large diameter wing 4 arranged above the tip wing 3 and having a second diameter larger than the first diameter, an intermediate wing 5 provided between the tip wing 3 and the large diameter wing 4 and having a third diameter between the first diameter and the second diameter, and an upper wing 6 arranged above the large diameter wing 5 and having a fourth diameter approximately equal to or smaller than the third diameter.

[0021] The tip wing 3 has an inner surface that is welded and fixed to the outer circumferential surface of the steel pipe pile 2 at a predetermined angle, is composed of a pair of extension wings 31, 32 that are arranged and fixed opposite each other, and has a first diameter.

[0022] The intermediate wing 5 has an inner surface that is welded and fixed to the outer peripheral surface of the steel pipe pile 2 at a predetermined angle, is composed of a pair of expansion wings 51, 52 that are arranged and fixed opposite each other, and has a third diameter.

[0023] The large diameter wing 4 has an inner surface that is welded and fixed to the outer circumferential surface of the steel pipe pile 2 at a predetermined angle, is composed of a pair of expansion wings 41, 42 that are arranged and fixed opposite each other, and has a second diameter.

[0024] The upper wing 6 has an inner surface that is welded and fixed to the outer circumferential surface of the steel pipe pile 2 at a predetermined angle, is composed of a pair of expansion wings 61, 62 that are arranged and fixed opposite each other, and has a fourth diameter.

[0025] The diameters of the blades 3, 5, 4, and 6 are in the relationship of first diameter<third diameter<second diameter, and the third diameter≈fourth diameter.

[0026] The fan blades 31, 51, 41, 61 and 32, 52, 42, 62 of the tip blade 3, the intermediate blade 5, the large diameter blade 3 and the upper blade 6 are arranged so as to form a pseudo-spiral.

[0027] 2 and 3, the tip blade 3, the intermediate blade 5, and the large-diameter blade 4 form a lower truncated cone shape 10 that narrows downward by connecting the respective outer circumferential edges 33, 53, and 43, and the large-diameter blade 4 and the upper blade 6 form an upper truncated cone shape 20 that narrows upward by connecting the respective outer circumferential edges 43 and 63. The generatrix of the side area of ​​the lower truncated cone shape 10 is inclined at a predetermined angle α with respect to the horizontal direction. This angle α is approximately 75°. As a result, the angle of the opposing generatrix of the lower truncated cone shape 10 becomes approximately 30°, which is the most efficient angle.

[0028] After the steel pipe pile is rotated and penetrated, compressed soil is filled in the space 7 between the tip wing 3 and the intermediate wing 5, the space 8 between the intermediate wing 5 and the large diameter wing 4, and the space 9 between the large diameter wing 4 and the upper wing 6. As a result, a diamond-shaped support portion 40, for example, is formed at the lower end of the steel pipe pile 2 by the lower truncated cone shape 10 and the upper truncated cone shape 20, so that the downward bearing force (compressive force) of the steel pipe pile 2, the upward pull-out force of the steel pipe pile 2, and the resistance to the moment applied to the left and right of the steel pipe pile 2 can be improved.

[0029] As a result, the effective area SL of the lower truncated cone shape 10 against the supporting force (compressive force) is the sum (SL=Sb+Ss1) of the base area Sb (Sb=S1-S2), obtained by subtracting the area S2 of the lower end of the steel pipe pile from the area S1 of the tip wing 3, and the side area Ss1 (Ss1=π(r1+r2)L1, assuming that the radius of the tip wing 3 is r1, the radius of the large diameter wing 4 is r2, and the generating line of the lower truncated cone shape 20 is L1). This allows the effective area to be significantly increased. Similarly, the effective area SU of the upper truncated cone shape 20 against a pulling force is the sum (SU = Sc + Ss2) of the base area Sc (Sc = S3 - S2) obtained by subtracting the area S2 of the steel pipe pile from the area S3 of the upper wing 3, and the side area Ss2 (Ss2 = π(r2 + r3)L2 when the radius of the upper wing 6 is r3, the radius of the large diameter wing 4 is r2, and the generating line of the upper truncated cone shape 20 is L2), and therefore the effective area can be significantly increased.

[0030] As explained above, according to the present invention, by making each of the wings 3, 4, 5, 6 pseudo-spiral, the pile can be driven in without disturbing the soil during penetration, the load in the extraction direction is distributed by the two wings 4, 6 that make up the upper truncated cone shape 20, the load in the compression direction is distributed by the three wings 3.4.5 that make up the lower truncated cone shape 10, and when the soil is screwed in, the helical wings 3, 4, 5, 6 are secured to the pile tip, which is formed into a shape (a so-called diamond shape) 40 that is a combination of the upper truncated cone shape 20 and the lower truncated cone shape 10, thereby realizing greater cross-sectional resistance in the vertical and horizontal directions. [Explanation of symbols]

[0031] 1 Multi-wing steel pipe pile 2 Steel pipe pile 3 Tip wing 4. Mid-wing 5 Large diameter blade 6. Upper Wing 7,8,9 space 10 Lower truncated cone shape 20 Upper truncated cone shape 40 Diamond Shape

Claims

1. The pile is composed of a steel pipe pile, a tip wing arranged at the tip of the steel pipe pile and having a first diameter, a large diameter wing arranged above the tip wing and having a second diameter larger than the first diameter, an intermediate wing provided between the tip wing and the large diameter wing and having a third diameter between the first diameter and the second diameter, and an upper wing arranged above the large diameter wing and having a fourth diameter approximately equal to or smaller than the third diameter; A multi-winged steel pipe pile, characterized in that the tip wing, the intermediate wing, the large diameter wing and the upper wing are connected at their outer edges to form a support portion with a diamond-shaped cross-section that reduces in diameter in the vertical direction.

2. The multi-winged steel pipe pile described in claim 1, characterized in that each of the tip wing, the intermediate wing, the large diameter wing and the upper wing has an inner surface that is inclined at a predetermined angle and welded to the outer circumferential surface of the steel pipe pile, and is composed of a pair of expansion wings that are arranged and fixed opposite each other, and the expansion wings of the tip wing, the intermediate wing, the large diameter wing and the upper wing are arranged so as to form a pseudo-spiral.

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