Steel pipe pile

Abstract

To provide a novel steel pipe pile that can achieve both excavation performance and load bearing capacity.SOLUTION: A steel pipe pile 22 has a small diameter portion 22a at a tip side to be driven into ground, a large diameter portion 22b at a rear end side opposite to the tip side, and a tapered portion 22c whose outer diameter decreases from the large diameter portion to the small diameter portion. The tapered portion 22c has a taper ratio of greater than 0.2.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a steel pipe pile that is driven into the ground to stably support an architectural structure. [Background technology]

[0002] Conventionally, when the hard ground that serves as the support layer of a structure is deep, it is necessary to drive piles of a transportable length while connecting them together. The tip of the pile, which is the part that reaches the hard ground, is preferably a smaller diameter pile because it improves penetration (excavation performance) when driving the pile. On the other hand, in shallow parts where the ground is relatively soft, a larger diameter pile is preferable because it increases strength when considering the load applied to the pile due to horizontal forces caused by earthquakes, etc. Therefore, a dissimilar diameter steel pipe pile that connects a large diameter pile material and a small diameter pile material has been devised (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2008-25156 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, the aforementioned different diameter steel pipe piles are used to join large and small diameter piles, and at least three types of parts are required for the entire foundation pile. In addition, the different diameter steel pipe piles need to be joined to other pile materials at the top and bottom, making the work complicated.

[0005] The present invention has been made in consideration of these circumstances, and one of its illustrative objects is to provide a new steel pipe pile that can achieve both excavation performance and load-bearing capacity as a foundation pile to be driven into the ground. [Means for solving the problem]

[0006] In order to solve the above problems, a steel pipe pile according to one embodiment of the present invention has a small diameter portion at a tip end side to be driven into the ground, a large diameter portion at a rear end side opposite to the tip end side, and a tapered portion whose outer diameter decreases from the large diameter portion toward the small diameter portion. The tapered portion has a taper ratio of greater than 0.2.

[0007] According to this embodiment, the large diameter portion that receives horizontal forces in the shallow part of the ground is made thicker to increase the load-bearing capacity, while the small diameter portion that is driven into the ground is made thinner, thereby improving excavation performance.

[0008] The small diameter portion may have a length of 50 to 250 mm. This makes it possible to form the small diameter portion by simply machining a short region of the end of a straight steel pipe having the same diameter as the large diameter portion.

[0009] If the diameter of the large diameter portion is D1 and the diameter of the small diameter portion is D2, the diameter reduction ratio ((D1-D2) / D1) may be 0.2 to 0.4, whereby a thinner small diameter portion can be formed from a thicker large diameter portion.

[0010] The outer diameter D2 of the small diameter portion is smaller than the outer diameter D1 of the large diameter portion by 40 mm or more. This makes it possible to realize a steel pipe pile having a larger large diameter portion and a smaller small diameter portion.

[0011] The overall length may be 3000 to 6000 mm, which allows the large diameter portion that receives horizontal force to be long while still satisfying portability.

[0012] The small diameter portion and the tapered portion may be pressed, so that the small diameter portion to which the pile driven into the ground is coupled and the tapered portion can be formed in a single step.

[0013] If the length of the large diameter portion is L1 and the length of the small diameter portion and the tapered portion is L2, then 2≦L1 / L2≦11 may be satisfied. This makes it possible to realize a steel pipe pile having a large diameter portion of sufficient length.

[0014] Any combination of the above components and any conversion of the present invention into a method, device, system, etc. are also valid aspects of the present invention. Effect of the Invention

[0015] According to the present invention, it is possible to realize a new steel pipe pile that can achieve both excavation performance and load-bearing capacity. [Brief description of the drawings]

[0016] [Figure 1] 1 is a front view showing a schematic configuration of a foundation pile according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a cross-sectional view of the steel pipe pile according to the present embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] The present invention will be described below with reference to the drawings based on the embodiments. The same or equivalent components, members, and processes shown in each drawing are given the same reference numerals, and duplicated descriptions are omitted as appropriate. The embodiments are illustrative and do not limit the invention, and all features and combinations thereof described in the embodiments are not necessarily essential to the invention. The steel pipe pile according to this embodiment can be used as a foundation pile that stably supports a structure by being driven into the bearing layer of the ground.

[0018] FIG. 1 is a front view showing a schematic configuration of a foundation pile according to this embodiment. When constructing an architectural structure 10 shown in FIG. 1, a foundation pile 12 may be driven below the ground surface H for earthquake resistance and to prevent the building from tilting. The foundation pile 12 is provided at its tip with an auger screw 16 capable of drilling down to the hard ground 14 that serves as the supporting ground. Generally, soft ground 18 spreads above the hard ground 14, and when excavating this, a pile with a small diameter is preferable from the viewpoint of excavation resistance. On the other hand, since a large horizontal force is generated in the upper part of the soft ground 18 when an earthquake occurs, the upper part of the foundation pile 12 needs to have a strength (load resistance) sufficient to prevent bending against the horizontal force.

[0019] Therefore, the foundation pile 12 in this embodiment has a small diameter pile 20 that can be dug deep using an auger screw 16, and a steel pipe pile 22 that has sufficient strength to withstand horizontal forces directly below the architectural structure 10.

[0020] 2 is a cross-sectional view of a steel pipe pile according to the present embodiment. A steel pipe pile 22 according to the present embodiment has a small diameter section 22a at the tip side that is driven into the ground, a large diameter section 22b at the rear end side opposite to the tip side, and a tapered section 22c whose outer diameter decreases from the large diameter section 22b toward the small diameter section 22a.

[0021] The steel pipe pile 22 according to this embodiment has a total length L of 3000 to 7000 mm. The maximum value of the total length L is a value taking into consideration the size of the manufacturing equipment, portability from the manufacturing site to the installation site, and product characteristics (the length of the portion receiving horizontal force). The minimum value of the total length L is a value taking into consideration manufacturing constraints and the length necessary to achieve a desired load resistance against horizontal force in a shallow part of the ground. The total length L is preferably 3000 to 6000 mm, and more preferably 3500 to 5000 mm.

[0022] The length L1 of the large diameter portion 22b is 1330 to 6000 mm. The maximum value of the length L1 is a value that allows the portion that receives the horizontal force to be longer within the entire length of the steel pipe pile 22. The minimum value of the length L1 is a value required for the portion that receives the horizontal force to obtain a desired load resistance. The length L1 is preferably 3000 to 4000 mm.

[0023] Length L2 from small diameter portion 22a to tapered portion 22c is 500 to 2529 mm. The maximum and minimum values ​​of length L2 are determined by taking into consideration the performance of an apparatus capable of manufacturing a small diameter portion by pressing a part of a tube with a constant outer diameter.

[0024] The outer diameter D1 of the large diameter portion 22b is 165.2 to 558.8 mm. The maximum value of the outer diameter D1 is determined by taking into consideration the performance of an apparatus capable of manufacturing a small diameter portion by pressing a portion of a pipe with a constant outer diameter. If the minimum value of the outer diameter D1 is smaller than this, a steel pipe pile with sufficient load resistance cannot be obtained, and the merit of using it as a steel pipe pile with a different diameter is small. The outer diameter D1 is preferably 300 to 450 mm.

[0025] The outer diameter D2 of the small diameter portion 22a is 114.3 to 406.4 mm. The maximum value of the outer diameter D2 does not need to be too large as long as it does not impede excavation performance, taking into consideration other piles at the tip side that are joined to the small diameter portion 22a. On the other hand, the minimum value of the outer diameter D2 is a value that takes into consideration the strength required when excavating and advancing the ground and the performance of the manufacturing equipment. The outer diameter D2 is preferably 250 to 350 mm.

[0026] The thickness T1 of the large diameter portion 22b is 5.0 to 19.0 mm. The maximum value of the thickness T1 is a value that allows press working by a machine, and if it is too large, processing becomes difficult. On the other hand, the minimum value of the thickness T1 is a value in the range in which the steel pipe does not crack during processing. The thickness T1 is preferably 10 to 15 mm.

[0027] The thickness T3 of the tapered portion 22c and the thickness T2 of the small diameter portion 22a are T2, T3 ≧ T1. When the tapered portion 22c and the small diameter portion 22a are formed by press working, the thicknesses T2, T3 are thicker than the thickness T1 of the large diameter portion 22b. The thicknesses T2, T3 are preferably 13 to 18 mm.

[0028] The small diameter portion 22a and the tapered portion 22c of the steel pipe pile 22 according to this embodiment are formed by press working using a mold. This allows the small diameter portion 22a and the tapered portion 22c to which the pile to be driven into the ground is connected to be formed in a single process.

[0029] [Example] As steel pipe piles having the above-mentioned ranges of each parameter, concretely, steel pipe piles of Examples 1 to 3 were produced. The values ​​of each parameter are shown in Table 1. [Table 1]

[0030] Table 2 shows the length L3 of the small diameter portion 22a and the length L2' (L2-L3) of the tapered portion 22c. [Table 2]

[0031] As shown in Table 2, the steel pipe pile 22 according to each embodiment has a taper ratio ((D1-D2) / L2') of more than 0.2. The large diameter portion that receives horizontal force in the shallow part of the ground is made thicker to increase the load-bearing capacity, while the small diameter portion that is driven into the ground is made thinner, thereby improving excavation performance. Furthermore, the narrowing of the small diameter portion makes it possible to reduce manufacturing costs and material costs.

[0032] The small diameter portion 22a of the steel pipe pile 22 according to each embodiment has a length L3 of 50 to 250 mm. This allows the small diameter portion 22a to be formed simply by processing a short area of ​​the end of a straight steel pipe having the same diameter as the large diameter portion 22b. The length L3 of the small diameter portion 22a is preferably 50 to 150 mm.

[0033] Moreover, as shown in Table 2, the steel pipe pile 22 according to each embodiment has a diameter reduction ratio ((D1-D2) / D1) of 0.2 to 0.4. This allows the thinner small diameter portion 22a to be formed from the thicker large diameter portion 22b. Specifically, the outer diameter D2 of the small diameter portion 22a according to each embodiment is smaller than the outer diameter D1 of the large diameter portion 22b by 40 mm or more. More preferably, the outer diameter D2 is smaller than the outer diameter D1 by 50.8 mm or more. This allows the steel pipe pile 22 to be realized, which has a thicker large diameter portion 22b and a thinner small diameter portion 22a.

[0034] Furthermore, as shown in Table 2, in the steel pipe pile 22 according to each embodiment, when the length of the large diameter portion 22b is L1 and the length of the small diameter portion 22a and the tapered portion 22c is L2, 2≦L1 / L2≦11 is satisfied. More preferably, 6≦L1 / L2≦11 is satisfied. This makes it possible to realize a steel pipe pile 22 having a large diameter portion 22b of sufficient length.

[0035] The material of the steel pipe pile 22 according to this embodiment is appropriately selected in consideration of strength, cost, and workability.

[0036] Although the present invention has been described above with reference to the above-mentioned embodiment, the present invention is not limited to the above-mentioned embodiment, and suitable combinations or substitutions of the configurations of the embodiment are also included in the present invention. In addition, it is possible to suitably rearrange the combinations and processing order in the embodiment based on the knowledge of a person skilled in the art, and to make modifications such as various design changes to the embodiment, and the embodiment to which such modifications have been made is also included in the scope of the present invention. [Explanation of symbols]

[0037] 10 building structure, 12 foundation pile, 14 hard ground, 16 auger screw, 18 soft ground, 20 small diameter pile, 22 steel pipe pile, 22a small diameter section, 22b large diameter section, 22c tapered section.

Claims

1. A tubular small diameter portion at the tip side that is driven into the ground and is joined to another pile; A tubular large diameter portion located at a rear end side opposite to the front end side and directly below the architectural structure; a tubular tapered portion whose outer diameter decreases from the large diameter portion toward the small diameter portion, The tapered portion has a taper ratio of greater than 0.2; The small diameter portion has a length of 50 to 250 mm, The large diameter portion has a length of 1330 mm to 6000 mm, When the length of the large diameter portion is L1 and the length of the small diameter portion and the tapered portion is L2, 2≦L1 / L2, The plate thickness of the small diameter portion is thicker than the plate thickness of the large diameter portion, The small diameter portion, the large diameter portion and the tapered portion are a single, seamless, hollow part. A steel pipe pile characterized by:

2. The steel pipe pile according to claim 1, characterized in that, when the diameter of the large diameter portion is D1 and the diameter of the small diameter portion is D2, the diameter reduction rate ((D1-D2) / D1) is 0.2 to 0.

4.

3. 3. The steel pipe pile according to claim 2, wherein an outer diameter D2 of the small diameter portion is smaller than an outer diameter D1 of the large diameter portion by 40 mm or more.

4. 3. The steel pipe pile according to claim 1 or 2, wherein the total length is 3000 to 7000 mm.

5. 3. The steel pipe pile according to claim 1, wherein the small diameter portion and the tapered portion are formed by pressing.

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