JP2008045338A - Steel pipe pile - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a steel pipe pile which can be easily screwed even into the hard ground. <P>SOLUTION: The steel pipe pile 1 has a platelike blade portion 2 on its front end 12, the blade portion 2 having an outer diameter larger than that of a cylindrical shaft 11. On the cylindrical outer shell of the front end 12, groovelike incisions 13 and 13 are formed at two spots by slantly incising a front end face 12a. Two blades 21 and 21 forming the blade portion 2 are inserted and fixed in the incisions 13 and 13, respectively. Left portions 141 are bent toward the plan view center C of the shaft 11 to form a front end projection 14 having a curved surface portion 14a. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a screw-in type steel pipe pile in which a blade portion having an outer shape larger than that of a shaft portion is provided at a tip portion.

  2. Description of the Related Art Conventionally, a bladed steel pipe pile is known in which a semicircular blade plate is obliquely attached to the tip of a steel pipe pile and screwed into the ground while rotating (see Patent Documents 1 to 3, etc.).

In these bladed steel pipe piles, the blades are inserted into the steel pipes, so that when the building weight or vertical force due to earthquake acts on the blades, the reaction force is balanced inside and outside the steel pipes. The steel pipe does not generate excessive bending stress.
Japanese Patent No. 2861937 JP 2006-177125 A JP 2004-257075 A

  However, the above-described bladed steel pipe pile is provided with a blade portion whose outer shape is larger than that of the cylindrical shaft portion, and its tip is completely closed by the blade portion, and is screwed into the ground without discharging. Therefore, the resistance from the ground to press-fitting is large, and it may be difficult to screw into an intermediate hard ground layer or support layer.

  Then, this invention aims at providing the steel pipe pile which is easy to screw in even if it is a hard ground.

  In order to achieve the above object, a steel pipe pile according to the present invention is a steel pipe pile having a plate-like blade portion having an outer shape larger than that of a cylindrical shaft portion at a tip portion, and is provided on a cylindrical outer shell of the tip portion. Groove-shaped cut portions cut obliquely from the front end surface are formed in at least two locations, and at least two blade plates forming the blade portions are respectively inserted into the cut portions and fixed, The cylindrical outer shell on the tip surface side from the cut portion is bent toward the center of the shaft portion in plan view to form a tip convex portion having a curved surface portion.

  Here, an opening may be formed in the blade portion near the center of the shaft portion in plan view.

  Moreover, the said front-end | tip convex part may be formed so that there may be no part which protrudes below from blades other than a directly upper blade plate in the side view of the said axial part.

  Furthermore, the said front-end | tip part may be formed separately from the axial part, and a front-end | tip part may be joined below the axial part to make a steel pipe pile.

  The steel pipe pile of the present invention configured as described above inserts a blade plate into a cut portion cut obliquely from the tip surface of the tip portion, and bends the arc-shaped outer shell below the blade plate toward the center. Thereby, the front-end | tip convex part which has a curved surface under a blade is formed.

  This tip convex part has a curved surface part, and when the steel pipe pile is rotated in a direction in which the curved surface side comes into contact with the earth and sand, the earth and sand below the slats are smoothly pushed outward along the curved surface.

  For this reason, the resistance from the ground is reduced, and the steel pipe pile can be easily screwed even in the hard ground.

  Moreover, since the earth and sand can be taken into the steel pipe pile by forming the opening near the center of the blade part, the resistance is reduced and the steel pipe pile can be easily screwed into the ground.

  Furthermore, by making the tip convex part fit in the ground cut by other blades, the resistance from the ground to the tip convex part is reduced, and the tip convex part is deformed or screwing resistance is increased. Can be prevented.

  Moreover, the steel pipe pile with a blade | wing part can be easily manufactured using a ready-made steel pipe by forming a front-end | tip part separately from a shaft part.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  FIG. 1 is a perspective view showing a configuration in the vicinity of the distal end portion 12 of the steel pipe pile 1 of the present embodiment.

  The steel pipe pile 1 has a shaft portion 11 formed of a cylindrical steel pipe, a tip portion 12 positioned below the shaft portion 11 when screwed into the ground, and a shaft portion 11 provided on the tip portion 12. Mainly composed of a blade portion 2 having a large outer shape and a tip convex portion 14 formed below the blade portion 2.

  In this embodiment, the tip 12 is formed at one end of the same steel pipe as the shaft 11, so that the steel pipe itself becomes a cylindrical outer shell.

  As shown in FIG. 2, a groove-shaped cut is obliquely formed in the cylindrical outer shell of the tip 12 from the tip surface 12a to form a cut 13. Here, the groove width of the cut portion 13 is set in accordance with the thickness of the blade 21 described later.

  The cut portion 13 is formed to be inclined at an angle of about 5 to 25 degrees with respect to the distal end surface 12a, and the inclination angle is preferably about 10 to 20 degrees. In the present embodiment, the inclination inclination angle is set to 15 degrees. The case where it is set in degrees will be described.

  Moreover, in this Embodiment, the notch | incision part 13 is provided in two places at the same angle at intervals in the circumferential direction of the front-end | tip part 12. FIG.

  As shown in FIG. 2, the notches 13 and 13 are formed every half of the tip 12, and the other notch 13 is formed from the bottom of the upper end that has been raised above the notch 13. Cut into.

  Further, the blade portion 2 is formed by two blade plates 21 and 21 inserted into the cut portions 13 and 13.

  The blade portion 2 is formed in a circular plate shape having a diameter of about 1.5 to 3.5 times the diameter of the shaft portion 11, and is formed by two semicircular blade plates 21 and 21 obtained by dividing the blade portion 2 into two equal parts. Composed.

  For example, in the case of the small-diameter steel pipe pile 1, the diameter of the blade portion 2 in plan view is set to 140 mm to 1000 mm with respect to the diameter of the shaft portion 11 of 70 mm to 500 mm. In the case of the steel pipe pile 1 having a large diameter, the diameter of the shaft part 11 is set to be 1200 mm to 2400 mm in a plan view of the blade part 2 with respect to 600 mm to 1200 mm.

  Moreover, although it changes with the magnitude | sizes of the design support force of the steel pipe pile 1, the steel plate of thickness 20mm-about 45mm is used for the blade board 21. FIG.

  Furthermore, on the diameter surface of the slat 21, a portion that drops when inserted into the cut portion 13, that is, a portion that cuts into the ground at the top of the rotation direction R when the steel pipe pile 1 is rotated, is cut obliquely. The blade part 21a is formed.

  The blades 21 and 21 are inserted into the cut portions 13 and 13, respectively, and the circular opening in the plan view of the shaft portion 11 is closed semi-circlely by the two blade plates 21 and 21 (see FIG. 4). .

  Further, when the blade plate 21 is inserted into the cut portion 13, a weld portion 22 is formed along the upper edge of the cut portion 13 and is fixed to the steel pipe.

  As shown in the side view of the steel pipe pile 1 in FIG. 3, the blades 21 and 21 inserted into the notches 13 and 13 formed every half circumference in the same direction in the circumferential direction as described above are in opposite directions in a side view. Looks like it leans to

  Here, on the tip surface 12a side of the cut portion 13, there is a remaining portion 141 in which the cylindrical outer shell remains in a triangular shape as shown in FIG. 2, and therefore, as shown in the bottom view of FIG. Is bent at the bent portion 14b so that the curved surface portion 14a passes through the center C in plan view.

  Similarly, the other remaining portion 141 is also bent at the bent portion 14b so that the tip of the curved surface portion 14a coincides with the tip of the other curved surface portion 14a at the center C in plan view. Here, in the case where the length of the remaining portion 141 is long and the tip of the curved surface portion 14a exceeds the center C in plan view and enters the region of the other blade plate 21, it may be cut or the curved portions 14a, 14a The tips may be overlapped.

  And the upper edge of curved surface part 14a, 14a is joined to the lower surface of the blades 21 and 21 by the welding part 22, and the front-end | tip convex part 14 is fixed.

  As shown in FIG. 4, since the curved surface portions 14 a and 14 a swell in the rotation direction R of the tip convex portion 14, when the ground cut by the blades 21 and 21 comes into contact with the curved surface portions 14 a and 14 a, The earth and sand will move along the curved surface.

  Next, the effect | action of the steel pipe pile 1 of this Embodiment is demonstrated.

  The steel pipe pile 1 of the present embodiment configured as described above inserts the blade plate 21 into the cut portion 13 cut obliquely from the tip surface 12 a of the tip portion 12, and the remaining portion below the blade plate 21. By bending 141 toward the center C in plan view, the tip convex portion 14 having a curved surface is formed below the vane plate 21.

  This tip convex part 14 has curved surface parts 14a, 14a, and when the steel pipe pile 1 is rotated in the rotation direction R in which the curved surface side comes into contact with the earth and sand, the earth and sand below the blades 21 are smoothly moved outward along the curved surface. Extruded.

  For this reason, the resistance from the ground by the cut earth and sand is reduced, and the steel pipe pile 1 can be easily screwed into the hard ground of the intermediate layer or the support layer penetration portion.

  Moreover, since the front-end | tip convex part 14 can be formed using a part of steel pipe, it is not necessary to prepare a member separately, and manufacture is also easy and it is economical.

  Furthermore, since the front-end | tip of the axial part 11 is obstruct | occluded by the blade | wing part 2, the bottom area of a pile can increase and the supporting force of a pile can be made to increase.

  Moreover, since this slat 21 is arranged inside and outside of the steel pipe, the portion protruding to the outside of the wing part 2 has received the reaction force of the ground from below due to the load of the building acting on the upper end of the shaft part 11. Even so, the resistance of the ground below the vane plate 21 arranged inside the steel pipe balances the inside and outside of the steel pipe, and the bending moment acting on the steel pipe with which the upper surface of the vane plate 21 abuts becomes small. For this reason, excessive bending stress is not generated in the steel pipe and it is not damaged, and the blade 21 is not bent.

  Hereinafter, Example 1 of the above-described embodiment will be described with reference to FIG. The description of the same or equivalent parts as those described in the above embodiment will be given the same reference numerals.

  1 A of steel pipe piles of this Example 1 are the axial part 11 formed with a cylindrical steel pipe similarly to the steel pipe pile 1 of the said embodiment, and the front-end | tip located under the axial part 11 when screwing in the ground It is mainly composed of a portion 12, a blade portion 2A having an outer shape larger than that of the shaft portion 11 provided at the tip portion 12, and a tip convex portion 14A formed below the blade portion 2A.

  And the front-end | tip convex part 14A of this Example 1 is formed so that there may be no part which protrudes below rather than the blade board 21B other than the blade board 21A right above in the side view of the axial part 11. FIG.

  That is, the tip convex portion 14A formed under the slat 21A shown in front of FIG. 5 has a triangular portion protruding downward from the lower surface of the back slat 21B as a cutout 142. ing.

  The cut portion 142 may be cut by cutting, but may be bent inward so as not to protrude downward from the lower surface of the rear blade 21B.

  By doing in this way, the ground which the front-end | tip convex part 14A contacts becomes the range of the ground cut by the blade board 21B, and only the front-end | tip convex part 14A receives a big resistance from the ground before cutting, and the phenomenon of deform | transforming. Generation can be reduced.

  In addition, since the tip convex portion 14A is less likely to be deformed, the soil removal function functions normally, and therefore, the excavated earth and sand below the blade portion 2A can be pushed outward to suppress an increase in screwing resistance.

  Other configurations and functions and effects are substantially the same as those in the above-described embodiment, and thus description thereof is omitted.

  Hereinafter, Example 2 of the above-described embodiment will be described with reference to FIG. The description of the same or equivalent parts as those described in the above embodiment will be given the same reference numerals.

  Similarly to the steel pipe pile 1 of the above-described embodiment, the steel pipe pile 1B of Example 2 also has a shaft portion 11 formed by a cylindrical steel pipe and a tip positioned below the shaft portion 11 when screwed into the ground. It is mainly composed of a portion 12, a blade portion 2B having a larger outer shape than the shaft portion 11 provided at the tip portion 12, and a tip convex portion 14B formed below the blade portion 2B.

  The blade portion 2B of the second embodiment is formed in a circular shape in plan view as shown in FIG. 6 by two semicircular blade plates 21C and 21C attached obliquely.

  Further, the vane plate 21C is formed in a semicircular shape, and the inside is notched by a semicircle that is concentric with the circle forming the outer shape.

  The bottom of the steel pipe pile 1B into which the blades 21C, 21C cut into a semicircular shape are inserted into the cut portions 13, 13, respectively, has a substantially circular opening near the center C of the shaft portion 11 in plan view. 23 is formed.

  By forming the opening 23 in the vicinity of the center C in plan view of the steel pipe pile 1B in this way, the cut soil can be taken into the inside of the steel pipe pile 1B, so that the resistance at the time of screwing is reduced and the steel pipe pile is reduced. 1B can be placed easily.

  That is, the earth and sand cut by the blade part 2B is carried to the outside by the tip convex part 14B, but the sand near the center C in plan view that takes time for soil removal by the action of the tip convex part 14B By taking in from 23 to the inside of a pile, the increase in resistance at the time of screwing can be suppressed rapidly.

  Other configurations and functions and effects are substantially the same as those of the above-described embodiment or Example 1, and thus description thereof is omitted.

  The best mode and examples of the present invention have been described in detail above with reference to the drawings. However, the specific configuration is not limited to this mode and examples, and does not depart from the gist of the present invention. A degree of design change is included in the present invention.

  For example, in this Embodiment and the Example, although the front-end | tip part 12 was provided in the edge part of the steel pipe which forms the axial part 11, it is not limited to this, The front end provided with the blade | wing part separately from the axial part It is good also as a steel pipe pile by manufacturing a part and joining the front-end | tip part under the axial part.

  Moreover, in this Embodiment and the Example, although the blade | wing part 2 (2A, 2B) was formed by the two blades 21 and 21 (21A, 21B, 21C, 21C), it is not limited to this. The blade portion can be formed by three or more blade plates. In that case, the notches are also formed in accordance with the number of blades, and the shape of the blades is a fan shape that is circular when all blades are combined.

  Furthermore, in the said embodiment and Example, although the planar view substantially circular blade | wing part 2 (2A, 2B) formed by the semicircular blade board 21 (21A, 21B, 21C) was demonstrated, it is limited to this. The blade portion may be a polygonal shape such as a hexagon or an octagon in plan view.

  In the above-described embodiment, the configuration in which the diameter surfaces of the two blades 21 and 21 coincide with each other in a plan view to close the lower opening of the shaft portion 11 without any gap has been described. However, the present invention is not limited thereto. Instead, for example, the configuration may be such that when viewed in a plan view, the two blade plates 21 and 21 are separated from each other and a groove-like gap is opened at the center of the blade portion.

It is a perspective view explaining the structure of the steel pipe pile of the best embodiment of this invention. It is explanatory drawing explaining the manufacturing method of the steel pipe pile of the best embodiment of this invention. It is a side view explaining the structure of the steel pipe pile of the best embodiment of this invention. It is a bottom view explaining the structure of the steel pipe pile of the best embodiment of this invention. It is a side view explaining the structure of the steel pipe pile of Example 1. FIG. It is a bottom view explaining the structure of the steel pipe pile of Example 2.

Explanation of symbols

1, 1A, 1B Steel pipe pile 11 Shaft part 12 Tip part 12a Tip face 13 Cut part 14, 14A, 14B Tip convex part 14a Curved part 142 Remaining part 142 Cut part 2, 2A, 2B Blade part 21, 21A-21C Blade 23 Opening C Center of shaft portion in plan view

Claims (4)

  A steel pipe pile having a plate-like blade portion whose outer shape is larger than that of a cylindrical shaft portion at a tip portion, and a groove-like cut portion cut obliquely from a tip surface into a cylindrical outer shell of the tip portion. At least two blade plates that are formed in at least two places and that form the blade portion are fixed in the cut portions, respectively, and the cylindrical outer shell on the tip surface side from the cut portion is fixed to the shaft. A steel pipe pile characterized in that a tip convex portion having a curved surface portion is formed by bending toward a center of the portion in plan view.   The steel pipe pile according to claim 1, wherein an opening is formed in the blade portion near the center of the shaft portion in plan view.   3. The steel pipe according to claim 1, wherein the tip convex portion is formed so as not to have a portion protruding downward from a blade plate other than a blade plate directly above in a side view of the shaft portion. Pile. The steel pipe pile according to any one of claims 1 to 3, wherein the tip portion is formed separately from the shaft portion, and the tip portion is joined below the shaft portion.

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