JP6644454B1 - Expanded steel pipe pile and expanded bottom integrated steel pipe - Google Patents

Abstract

The present invention provides a steel pipe pile with an expanded bottom capable of forming a sufficiently large expanded portion with a simple structure and obtaining a large supporting force, and an integrated steel pipe with an expanded bottom that can improve construction efficiency. A shaft steel pipe that is a pile steel pipe main body, an expanded bottom steel pipe larger in diameter than the shaft steel pipe connected to a lower end of the shaft steel pipe, and a circular steel pipe joined to a lower end of the expanded steel pipe. It comprises a tip member 4 which serves as an excavating bottom and at the same time exerts an excavating driving force. It is not a structure in which the shaft steel pipe is directly joined to the tip member, but a structure in which it is joined to the tip member by interposing a steel pipe with a larger diameter than the shaft steel pipe. It is possible to obtain a large supporting force as an expanded steel pipe pile. [Selection diagram] Fig. 1

Description

  The present invention relates to an expanded steel pipe pile constructed by a rotary press-fitting method, and an expanded bottom integrated steel pipe used as an expanded bottom portion of the expanded steel pipe pile.

  The expanded pile method is employed in the cast-in-place concrete method, but is also employed in the steel pipe pile by the rotary press-in method (Patent Documents 1, 2, 3, and 4). Each patent document will be described below using the respective reference numerals.

  The expanded steel pipe pile 1 of Patent Literature 1 has a structure in which a steel plate (pile steel pipe) 2 is provided with a steel plate (pile steel pipe) 2 and a steel plate having a substantially square shape attached to a distal end surface thereof. An inclined surface portion 32 is formed.

  The expanded steel pipe A of Patent Document 2 has a configuration in which a truncated conical bottom support wing 2 'is connected to a small diameter steel pipe 1 which is a shaft steel pipe by an inclined reinforcing member 3'.

  The rotary press-fitting expanded steel pipe pile 1 of Patent Document 3 has a connection bottom having a bottom plate 4, a cutting wing 5 formed as a cutout of the bottom plate 4, and a tip cutting blade 6 at the tip of the pile body 2. This is a configuration in which a tube 3 is provided.

The expanded steel pipe pile A of Patent Literature 4 includes an expanded bottom portion 2 fixed to a lower end portion of a steel pipe 1 as a steel pipe pile main body, and a press-fit portion 3 fixed to a lower end portion of the expanded bottom portion 2.
The expanded bottom portion 2 has a plurality of hot-melt synthetic resin bags 13 filled with a water reaction expanding material 12 inside and outside the concave portions 6 of the intermediate steel material 5, and is attached to a mounting plate 4 fixed to a lower end portion of the steel pipe 1. Each bag 13 is surrounded by a plurality of curved pressing plates 8 having their upper ends swingably connected, and the outer periphery of the lower part of each of the pressing plates 8 is tightly bound by a hot-melt synthetic resin band 14. Formed.
As the press-fitting part 3, a tip drilling excavating blade 17 and a drilling cone 18 are provided.

JP 2006-127267 A JP-A-2002-212947 JP 2006-177101A JP-A-2002-339352

In each of Patent Documents 1 to 4, the expanded bottom plate 3 (Patent Document 1), the expanded bottom support wing 2 ′ (Patent Document 2), the expanded bottom plate 4 (Patent Document 3), and the expanded bottom portion 2 are directly connected to the pile body steel pipe (shaft steel pipe). (Patent Literature 4) is provided, and a sufficiently large enlarged bottom cannot be formed.
Further, Patent Document 4 has a special structure in which a plurality of heat-fusible synthetic resin bags 13 filled with the water reaction expanding material 12 are arranged, and cannot be easily manufactured.

  SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional drawbacks, and has an expanded steel pipe pile capable of forming a sufficiently large expanded portion with a simple structure and obtaining a large supporting force, and improving construction efficiency. An object of the present invention is to provide an expanded bottom integrated steel pipe.

The expanded steel pipe pile according to the first aspect of the present invention, which solves the above problem, comprises: a shaft steel pipe as a pile steel pipe main body; an expanded steel pipe having a larger diameter than the shaft steel pipe joined to a lower end of the steel shaft pipe; A bottom-end steel pipe pile formed by a rotary press-fitting method , comprising a circular bottom portion and a tip member that exerts excavation propulsion force, which is joined to a lower end of the steel pipe pile ,
The tip member, the lower end surface of the拡底side steel pipe, been welded large circular end plates than拡底side steel tube diameter d ₁ is the diameter D _0, protruding outward from the outer periphery of the拡底side steel pipe in the end sheet and the flange portion has a notch toward the center from the end face plate periphery, the end face plate both circumferential sides of the notch has a configuration which is formed inclined surface which is inclined vertically opposite directions,
Junction structure between said shaft steel pipe the拡底side steel pipe, circular flat plate of the拡底side the same diameter as the steel tube diameter d ₁ is fixed by welding to the upper end of the拡底side steel pipe, the shaft steel tube diameter d on the upper surface of the circular flat plate ₂ the same diameter or the short tube of the thick than the shaft steel pipe with a large diameter than 2mm fixed by welding, the length of the short tube is the inner surface welding is possible lengths for the circular flat plate, said short tube And a lower end of the shaft steel pipe is welded.

Claim 2 is the拡底steel pipe pile according to claim 1, wherein the end face plate of the tip member, the recess of the circular contour of diameter D ₁ slightly concaved pile cranial formed as viewed from the lower surface side in the center portion is an end plate, characterized in that the flange protruding from the outside the recess in the end face plate, is the inclined surface portion is formed configured inclined upside down to each other physician.

The expanded bottom integrated steel pipe of the invention according to claim 3 is an expanded bottom integrated steel pipe used when constructing an expanded bottom steel pipe pile by a rotary press-in method.
At the lower end, a tip member that exerts a driving force for excavation at the same time as the circular bottom portion is larger in diameter and thicker than the shaft steel tube, which is the pile body steel pipe.
The welded fixed with the拡底side steel tube diameter d ₁ and a circular flat plate having the same diameter at the upper end of拡底side steel pipe, the said axis steel pipe diameter d ₂ and the diameter or welded fixed to the upper surface of the circular flat plate large within 2mm Bei example a short tube of the thick from the shaft steel tube diameter, the length of the short tube, characterized in that it is a inner surface weld length possible for the circular plates.

According to the expanded steel pipe pile of the present invention, the shaft steel pipe, which is the pile steel pipe main body, is not a structure in which the circular expanded bottom portion is directly joined to the tip member that exerts the digging propulsion force, but has a larger diameter than the shaft steel pipe. Since the structure is joined to the tip member with the steel pipe on the expanded bottom side interposed, the outer diameter of the end plate of the tip member, which is a circular expanded part, can be enlarged, and a large supporting force can be obtained as a steel pipe pile with expanded bottom. Becomes
In other words, when simply increasing the outer diameter of the end face plate to obtain a large bearing capacity as an expanded steel pipe pile, if the small-diameter shaft steel pipe is directly welded and fixed to the large-diameter end face plate, it will be located in the narrow area at the center of the end face plate. Since concentrated load acts, the end plate (tip member) does not always work effectively as a bottom-enlarged part due to its rigidity, but the concentrated-side steel pipe fixed to the end plate by welding is large in diameter, so the concentrated load is reduced. , Effectively acting as a widened bottom.

  According to the expanded steel pipe pile of claim 2, the end face plate of the tip member welded and fixed to the lower end of the expanded steel pipe has, at the center thereof, a concave portion having a circular contour depressed toward the pile head when viewed from the lower surface side. Since the contact surface with the soil is large, a higher supporting force can be obtained than when the end face plate is a simple flat plate. Therefore, the effect of the steel pipe on the expanded bottom side according to claim 1 having the effect of increasing the maximum construction depth can be further enhanced.

In addition, according to the expanded steel pipe pile of the present invention, the shaft steel pipe and the expanded steel pipe are welded and fixed to a circular flat plate that is welded and fixed to the upper end of the expanded steel pipe, and a short pipe thicker than the shaft steel pipe is interposed. Because of the structure in which the pipes are joined together, the strength of the different-diameter pipe joint between the shaft steel pipe and the expanded-side steel pipe can be secured.

According to the invention of claim 3 , at the construction site, the expanded steel pipe pile is constructed by welding and connecting the shaft steel pipe to the short pipe of the expanded bottom integrated steel pipe already manufactured at the factory, so that the shaft steel pipe and the expanded bottom steel pipe are connected. Can be joined with high joining strength, and the construction efficiency on site is significantly improved.

It is the figure which showed the expanded steel pipe pile of one Example of this invention by omitting two parts of the longitudinal direction. It is an enlarged view of a portion A of FIG. It is AA sectional drawing of FIG. It is BB sectional drawing of FIG. (A) is a diagram illustrating a reinforcing member portion in FIGS. 2 to 4, and (B) is a diagram illustrating a joint portion (sand hatched portion) with a downward inclined surface portion in the inclined surface portion reinforcing member of (A). . (A) is an enlarged sectional view of an essential part of a portion B in FIG. 1, and (B) is a BB sectional view of (A). It is the figure which showed the part of the expanded bottom integrated steel pipe 7 in FIG. 1 without omitting length (the figure shown independently as an Example of the expanded bottom integrated steel pipe of Claim 5).

  Hereinafter, embodiments for implementing 拡底 steel pipe pile of the present invention, and 拡底 portion integral steel pipe used as 拡底 portion of the 拡底 steel pipe pile are described with reference to the drawings.

FIG. 1 is a view showing an expanded steel pipe pile according to an embodiment of the present invention with two parts omitted in a longitudinal direction. 2 is an enlarged view of a portion A in FIG. 1, FIG. 3 is a sectional view taken along line AA in FIG. 2, and FIG. 4 is a sectional view taken along line BB in FIG.
As shown in these figures, the expanded steel pipe pile 1 of the embodiment includes a shaft steel pipe 2 which is a pile steel pipe main body, an expanded steel pipe 3 joined to a lower end of the steel pipe 2, and a lower end of the expanded steel pipe 3. And a tip member 4 which is a circular expanded bottom and exerts a driving force for excavation.
The expanded bottom steel pipe 3 of the embodiment is connected to the shaft steel pipe 2 via a thick short pipe 5 having substantially the same diameter as the shaft steel pipe 2.
As shown in FIG. 7, the portion of the expanded bottom steel pipe 3, the tip member 4, and the short pipe 5 are referred to as the expanded bottom integrated steel pipe 7. Regarding the length of the shaft steel pipe, the short pipe 5 is regarded as a part of the shaft steel pipe 3. .

As shown in FIGS. 2 to 4, the distal end member 4 of the embodiment includes an end face plate 10 welded and fixed to the lower end of the expanded steel pipe 3.
As shown in FIG. 3, the end face plate 10 has a diameter D ₀ larger than a diameter d _{1 of the} steel pipe 3 on the expanded bottom side, and has a pile head at the center as viewed from the lower surface side as shown in FIGS. recesses of circular contour of diameter D ₁ slightly concaved side (convex portion when seeing from above) 11 is formed (a circle indicated by symbol (11) in FIG. 3 is a contour line of the upper surface of the recess 11). A flange portion 12 of the end face plate 10 which protrudes outward from the concave portion 11 has a notch portion 13 extending from the peripheral edge of the end face plate toward the center. The inclined surface parts 14a and 14b which are inclined in opposite directions are formed. The upwardly inclined surface is indicated by reference numeral 14a, and the downwardly inclined surface is indicated by 14b.

In addition, as shown in FIGS. 2 to 4, the distal end member 4 of the embodiment is formed by welding an elongated member 16 extending from the center to the vicinity of the notch to the concave portion 11 on the back surface of the end plate 10. It is fixed. The elongated member 16 can suppress an increase in resistance of the soil to the excavation promotion of the steel pipe pile.
Further, as shown in the detailed views of FIGS. 2 to 4 and FIGS. 5A and 5B, the end face plate 10 is provided with an inclined surface portion reinforcing member 17 for reinforcing the downward inclined surface portion 14b on the back surface of the end surface plate 10. And the side surface thereof is fixed by welding to the side surface of the downward inclined surface portion 14b. The outline of the hatched portion in FIG. 5 (b) indicates a welded portion to the side surface of the downwardly inclined surface portion 14b.
The inclined surface portion reinforcing member 17 prevents the downward inclined surface portion 14b which receives a large resistance against the action of excavating the soil from being deformed.

The shaft steel pipe 2 is connected to the expanded bottom steel pipe 3 via the short pipe 5 as described above. FIG. 6 shows details of the joint structure 20 between the shaft steel pipe 3 and the expanded steel pipe 3.
A circular flat plate 21 having the same diameter as the expanded bottom steel pipe diameter d ₁ is fixed to the upper end of the expanded bottom steel pipe 3 by welding, and a shaft having the same diameter as or slightly larger than the diameter d ₂ of the shaft steel pipe 2 is mounted on the upper surface of the circular flat plate 21. A short pipe 4 thicker than the steel pipe 2 is fixed by welding, and an upper end of the short pipe 4 and a lower end of the shaft steel pipe 3 are welded to each other.
The short pipe 5 is welded and fixed to the upper surface of the circular flat plate 21 which has been welded and fixed to the steel pipe 3 on the expanded bottom side by full-length fillet welding on both the inner and outer surfaces. . Thereby, a sufficiently high strength welded joint is performed.

If the dimensions of each part is assumed as拡底steel pipe pile 1 of the above embodiment, for example, the total length L ₀ of拡底steel pipe pile 1 is 34m, the length L ₁ of the shaft steel pipe 2 is 30 m, the拡底side steel pipe 3 length and _{L 2} is 4.5m. The outer diameter _{d 2} of the shaft the steel pipe 2 is 190.7Mmfai, plate thickness 9 mm, an outer diameter _{d 1} of拡底side steel tube 3 is 273Mmfai, plate thickness 15 mm, an outer diameter _{d 3} of the short pipe 5 192Mmfai, thickness Is 15 mm and the height is 150 mm.
Naturally, appropriate length and thickness are selected according to the actual construction ground conditions.

When the expanded steel pipe pile 1 is rotationally press-fitted into the ground by a pile driver having a rotary press-fitting drive unit, the end plate 10 of the tip member 4 exerts a propulsive force in such a manner that the inclined surfaces 14a and 14b bite into the soil. . When the distal end member 4 reaches the support layer, the support force is high due to the presence of the concave portion 11 having a large contact area with the soil on the lower surface of the end face plate 10.
The tip member may have a simple flat end face plate having no concave portion.

According to the above-described expanded steel pipe pile 1, the shaft steel pipe which is the pile steel pipe main body is not a structure in which the circular expanded bottom portion is directly joined to the tip member which exerts the excavation driving force at the same time. Since it is a structure joined to the tip member 4 with the expanded bottom steel pipe 3 interposed, the outer diameter of the end face plate 10 of the tip member 4 which is a circular expanded portion can be increased, and a large supporting force as a expanded steel pipe pile can be obtained. It is possible to obtain.
In other words, when simply increasing the outer diameter of the end face plate to obtain a large bearing capacity as an expanded steel pipe pile, if the small-diameter shaft steel pipe is directly welded and fixed to the large-diameter end face plate, it will be located in the narrow area at the center of the end face plate. Since the concentrated load acts, the end face plate (tip member) does not always work effectively as the expanded part because of its rigidity. However, in the expanded steel pipe pile 1 of the present invention, the expanded steel pipe fixed to the end face plate 10 by welding. Since 3 has a large diameter, the concentrated load is reduced, and effectively acts as an expanded bottom portion.

  In the case of a steel pipe pile, if the maximum construction depth of, for example, 130 times the steel pipe pile diameter (shaft steel pipe diameter) is possible depending on the ground conditions, the expanded bottom steel pipe 3 having a diameter larger than the shaft steel pipe 2 exists at the tip of the pile. Thus, it is possible to further increase the maximum construction depth. In that case, depending on the ratio of the length of the expanded steel pipe to the total length of the expanded steel pipe pile (the sum of the length of the shaft steel pipe and the length of the expanded steel pipe) (ratio of the expanded steel pipe), the material of the pile is shorter than that of a steel pipe pile having the same diameter. Cost (steel material cost) can be saved.

That is, if the length L of the expanded steel pipe 3 is too short, the effect of providing the expanded steel pipe (the effect that the maximum construction depth can be increased) is not obtained, and if it is too long, the maximum construction depth is increased. Even if it can be done, the material cost (steel material cost) becomes too high, and there is no point in adopting it in terms of cost effectiveness. Therefore, it is preferable to perform a loading test to obtain an appropriate length (ratio of the steel pipe on the expanded bottom side) at which high cost-effectiveness can be obtained. This makes it possible to construct an expanded steel pipe pile in which material costs (steel material costs) are saved as compared with steel pipe piles having the same pile length.
If the length L of the拡底side steel tube 3 is from 5 to 20% of the total length L ₀ of拡底steel pipe pile 1, by performing a loading test, to obtain the appropriate拡底side steel ratio cost-effective is obtained It is possible.

When constructing the expanded steel pipe pile of the present invention, the tip member 4 can be fixed to the lower end of the expanded steel pipe 3 by welding and the short pipe 5 can be fixed to the upper end by welding in advance in a factory. FIG. 7 shows only the steel pipe 7 with the expanded portion, in which the expanded steel pipe 3, the tip member 4 and the short pipe 5 are integrated.
By manufacturing this expanded bottom integrated steel pipe 7 in advance at the factory, the expanded bottom steel pipe pile 1 is constructed by welding and connecting the shaft steel pipe 2 to the short pipe 5 of the expanded bottom integrated steel pipe 7 at the construction site. In addition, the shaft steel pipe 2 and the expanded steel pipe 3 can be joined with a high joining strength, and the construction efficiency on site is significantly improved.

REFERENCE SIGNS LIST 1 expanded bottom steel pipe pile 2 shaft steel pipe 3 expanded bottom side steel pipe 4 tip member 5 short pipe 7 expanded bottom integrated steel pipe 10 end face plate 11 recess 12 flange 13 notch 14 a (inclined upward) inclined surface 14 b (inclined downward) Inclined surface portion 16 Slender member 17 Inclined surface portion reinforcing member 20 Joint structure (of shaft steel pipe and expanded steel pipe) 21 Flat plate (of joint structure)

Claims (3)

A shaft steel is pile steel body, and 拡底 side steel pipe diameter than the shaft steel joined to a lower end of the shaft steel pipe, which is joined to the lower end of the 拡底 side steel pipe, both a circular 拡底 section excavation An expanded steel pipe pile made by a rotary press-fitting method consisting of a tip member exhibiting propulsion ,
The tip member, the lower end surface of the拡底side steel pipe, been welded large circular end plates than拡底side steel tube diameter d ₁ is the diameter D _0, protruding outward from the outer periphery of the拡底side steel pipe in the end sheet The flange portion has a cutout portion extending from the peripheral edge of the end face plate toward the center, and on both sides of the cutout portion in the circumferential direction of the end face plate, an inclined surface portion inclined upside down is formed ,
Junction structure between said shaft steel pipe the拡底side steel pipe, circular flat plate of the拡底side the same diameter as the steel tube diameter d ₁ is fixed by welding to the upper end of the拡底side steel pipe, the shaft steel tube diameter d on the upper surface of the circular flat plate ₂ the same diameter or the short tube of the thick than the shaft steel pipe with a large diameter than 2mm fixed by welding, the length of the short tube is the inner surface welding is possible lengths for the circular flat plate, said short tube Characterized in that the upper end of the steel pipe is welded to the lower end of the shaft steel pipe. It said end sheet of said tip member is a central end face plate concave circular contour is formed in a diameter D ₁ slightly concaved pile head side as viewed from the lower surface side to the outside than the recesses in the end face plate the overhanging flange portion,拡底steel pipe pile according to claim 1, characterized in that the said inclined surface portion is formed configured inclined upside down to each other physician. An integrated steel pipe with an expanded bottom used for construction of an expanded steel pipe pile by a rotary press-in method,
At the lower end, a tip member that exerts a driving force for excavation at the same time as the circular bottom portion is larger in diameter and thicker than the shaft steel tube, which is the pile body steel pipe.
A circular flat plate of the same diameter as the拡底side steel tube diameter d ₁ which is welded and fixed to the upper end of the拡底side steel pipe,
Wherein the shaft steel pipe diameter d ₂ and the diameter or welded fixed to the upper surface of the circular flat plate and a short pipe from axial steel of the thick large size within 2 mm, a length of the short tube on the circular flat plate An expanded bottom integrated steel pipe having a length that allows internal welding .

Images