JP3917728B2 - Steel pipe pile and foundation method using the same steel pipe pile - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a steel pipe pile and a steel pipe pile that serve as foundation reinforcement when a building such as a relatively low-rise two-storied house is constructed on an extremely soft ground having an N value of less than 10 that is a hardness indication of the boring. It relates to the basic construction method using
[0002]
[Problems to be solved by the invention]
Conventionally, when constructing a foundation of a low-rise building such as a two-story house, a foundation width that is an interval between foundations is set according to the strength of the ground. For example, 1m² In the case of ground with a bearing capacity of 5 TON or more per base, the foundation width is 500 mm and 1 m² In the case where the bearing capacity is only 3 TON per hit, it is common to set the base width to 800 mm wide.
[0003]
By the way, when the ground surface is soft ground, in order to build the foundation of a two-story house, a so-called deep foundation method is constructed in which the bottom surface of the foundation is constructed by excavating to a depth where there is a relatively hard ground layer with earth resistance. However, in soft ground where the water level is high, when excavating the ground, it is necessary to make earth retaining or drain (change water) so that the earth and sand will not fall down and the groundwater will not come out and accumulate. The foundation construction is difficult.
[0004]
On the other hand, when adopting a pile foundation, it is desirable that the ground supporting the pile has an N value of at least 15 indicating the hardness of the boring and a hardness of about 30 N value. In the case of soft ground, the layer having an N value of about 30 has a depth of about 10 to 15 m from the ground. By the way, the bearing capacity of the pile is represented by [constant 30 × N value 30 × tip cross-sectional area of the pile] × (1/3). For example, when the cross-sectional area of the pile is 0.049, one pile The hit support force is 14.7 tons (about 15 tons). When using a 5 ton foundation, as described above, assuming that the foundation width is 500 mm and a load is received at a pitch of 2 m, the load applied to the pile is only about 5 tons × 500 mm × 2,000 mm = 5 tons, Supporting this with a pile having a bearing capacity of about 15 tons is wasteful (uneconomical) even if the safety factor is estimated high.
[0005]
In addition, when considering arranging the piles according to the bearing capacity of the piles, the pile with a bearing capacity of 15 tons is too wide as the distance between the piles is 6 m. It is necessary to set a large cross-sectional area, resulting in uneconomical results.
[0006]
Furthermore, when steel pipe piles with a small tip cross-sectional area of about 100 mm to 150 mm in diameter and a bearing capacity of about 3 to 4 tons are used and driven at 1.8 m intervals, the length is about 10 to 15 m. Pile is required, and construction costs will rise.
[0007]
According to the survey results on foundation construction, it has been found that about 70% of the causes of uneven settlement of houses are caused by soft ground below the ground surface from 3m to 4m. In the ground deeper than 4m to 5m from the ground surface, it has been consolidated by the earth and sand in the upper layer, and the strength of the ground is not enough to support the pile, but is somewhat stronger. For this reason, it has been proposed to support a house by constructing a so-called apple concrete foundation filled with concrete in the excavation hole by the deep foundation method or partial excavation, but as explained in the deep foundation method described above In soft ground with high water level, earth retaining sheet piles and drainage are required for excavation, and construction is difficult in small houses with small sites.
[0008]
In recent years, instead of the deep foundation method, for example, a method of forming a foundation by mixing and stirring soil cement and earth and sand at a construction site has been adopted. According to this construction method, ground improvement columns with a diameter of 50 cm to 60 cm and a length of around 5 m to 6 m, in which earth and sand at the construction site are hardened with soil cement, are used as the foundation of a two-story house. To do.
[0009]
However, the properties of naturally formed earth and sand vary greatly depending on the region, etc., and it is difficult to mix and agitate the soil cement to form a ground improvement column with uniform quality without variation. For example, earth and sand and soil cement are mixed and stirred in accordance with the properties of the earth and sand, but the stirring conditions, time, etc. are different, and it is almost impossible to avoid variations in quality.
[0010]
In addition, it is said that in the ground improvement column, friction force is generated between the soil around the column body and this friction force is said to be one of the forces that support the ground improvement column in the ground. Frictional force is not exhibited as much as you did. For this reason, the load of the building acts on the tip of the ground improvement column from the upper end, while the reaction force of the ground acts on the tip (cross section), but most of this axial load is made only by the ground improvement column. If there is variation in the quality of the ground improvement pillars that are supported, the pillars will buckle and cause uneven settlement.
[0011]
When building foundations on soft ground where it is difficult to use support piles, deep foundation construction methods, apple concrete foundation construction methods, ground improvement column construction methods, etc. are known, but as mentioned above, all have various problems. Have
[0012]
The present invention has been made in view of the above circumstances, and aims to provide a steel pipe pile that can be applied to soft ground that is safe and very simple to construct, and is difficult to use a support pile. To do. Another object of the present invention is to provide a new foundation method that replaces the deep foundation method and the ground improvement column method using this steel pipe pile.
[0013]
[Means for Solving the Problems]
In the present invention that achieves the above object, the N value is less than 10 which is difficult to use as a foundation in a normal steel pipe pile provided with a spiral wing having an outer diameter of 2 to 3 times the diameter of the steel pipe. In order to be applicable to the ground, the first feature is that a spiral wing having an outer diameter of 5 to 6 times its diameter is provided on a steel pipe. The second feature is that a peripheral wall is provided on the peripheral edge of the lower surface of the spiral wing so as to constrain and compress the sediment so as to wrap the sediment in the lower part of the spiral wing and to obtain a supporting force by the consolidation effect of the sediment. have.
[0014]
That is, the first aspect of the present invention is an expanded bottom steel pipe pile that is difficult to use as a foundation for a support pile and is applied to an ultra-soft ground having an N value of less than 10, and is a steel pipe (short pipe). A helical bottom plate (spiral wing) having a diameter of 5 to 6 times its diameter is fixed.
[0015]
The spiral bottom plate (spiral wing) is provided with a peripheral wall along the periphery of the lower surface thereof.
[0016]
In addition, an expanded bottom steel pipe pile with a spiral bottom plate (spiral wing) fixed to a steel pipe (short pipe) having a diameter of about 5 to 6 times its diameter, an ultra-soft ground with an N value of less than 10. It is propelled and rotated without draining, and the load of the building is transmitted to the strong ground located below the super soft ground through the steel pipe and the spiral bottom plate, and the building is placed on the super soft ground. It is characterized by supporting.
[0017]
In addition, a spiral bottom plate (spiral wing) having a diameter of about 5 to 6 times its diameter is fixed to a steel pipe (short tube), and the spiral bottom plate (spiral wing) is attached to the periphery of the lower surface thereof. When the steel pipe pile with a peripheral wall is rotated and propelled in the ultra-soft ground with an N value of less than 10, it is restrained so that the peripheral wall wraps the earth and sand under the spiral bottom plate (spiral wing). It is characterized by supporting the building on the super soft ground by the consolidation effect by the peripheral wall and the support pressure by the spiral bottom plate (spiral wing) after the steel pipe pile is buried.
[0018]
You may make it fix the bottom plate which has the leading member for a excavation blade or rotation center deviation prevention to the front-end | tip (lower end) of the said steel pipe (short length pipe | tube).
[0019]
In addition, the peripheral wall may be formed integrally with the spiral bottom plate (spiral wing). Further, in the spiral bottom plate (spiral wing) formed integrally with the peripheral wall, an uneven portion may be formed in order to increase the bending strength.
[0020]
According to the first aspect of the present invention, when a bottom-extended steel pipe pile is rotated and propelled to the depth of 4 to 5 m from the ground surface on ultra-soft ground having an N value of less than 10, the spiral bottom plate has an N value. Achieving a ground with some strength of 4-5. This ground cannot support a support pile having a spiral wing about twice the diameter of the steel pipe, but can support a spiral bottom plate having a diameter five to six times that of the steel pipe. The load of the building acts on the spiral bottom plate from the steel pipe, and is distributed to a load of 1/25 to 1/36 of the magnitude from the spiral bottom plate, so that the strength is located in the lower layer of the spiral bottom plate. It will be transmitted to a certain ground.
[0021]
And when the peripheral wall is provided in the lower surface periphery of the spiral bottom plate (spiral wing), when the steel pipe pile is rotated and propelled in the ground, the peripheral wall wraps the earth and sand in the lower part of the spiral bottom plate (spiral wing). After the steel pipe piles are buried, the consolidation effect by the peripheral wall and the support pressure by the spiral bottom plate can be combined to support the building on the very soft ground.
[0022]
Further, according to the second aspect of the present invention, a plurality of spiral wings are arranged at appropriate intervals along the axial direction on the outer peripheral surface of the steel pipe, and the spiral shape arranged at the lowermost portion of these spiral wings. The outer diameter of the wing is set to 2 to 3 times the diameter of the steel pipe, the outer diameter gradually increases from the lowermost spiral wing in accordance with the spiral wing disposed on the upper part of the steel pipe, and Each spiral wing is provided with a peripheral wall along the periphery of the lower surface thereof.
[0023]
Further, a plurality of spiral wings are arranged at appropriate intervals along the axial direction on the outer peripheral surface of the steel pipe, and the outer diameter of the spiral wing arranged at the bottom of these spiral wings is set to the diameter of the steel pipe. The outer diameter is set to 2 to 3 times so that the outer diameter sequentially increases from the lowermost spiral wing to the spiral wing arranged at the upper part of the steel pipe, and the lower peripheral edge of each spiral wing The steel pipes each provided with a peripheral wall are rotated and propelled into the ultra-soft ground having an N value of less than 10 without soil, and the peripheral wall is restrained so as to wrap the earth and sand under the spiral bottom plate. After the steel pipe piles are buried, the building is supported on the super soft ground by the consolidation effect by the peripheral wall and the support pressure by the spiral bottom plate.
[0024]
According to the second aspect of the present invention, in addition to the supporting pressure by each spiral wing, there is a consolidation effect by the peripheral wall of each spiral wing, so that the building is supported even in an extremely soft ground having an N value of less than 10. can do. In addition, the outer diameter gradually increases from the lowermost spiral wing to the spiral wing placed on the upper part of the steel pipe, and as a whole becomes conical, only the vertical support pressure by each spiral wing In addition, the wedge effect works and a support pressure in an oblique direction is also applied, so that a large supporting force can be obtained.
[0025]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of a steel pipe pile according to the present invention will be described with reference to the accompanying drawings.
[0026]
1 is a partially omitted front view showing a first embodiment of a bottomed steel pipe pile according to the first aspect of the present invention, FIG. 2 is a perspective view of the spiral bottom plate of FIG. 1, and FIG. 3 is a spiral bottom plate. 4 is a perspective view of the spiral bottom plate of FIG. 3, FIG. 5 is a perspective view of another modification of the spiral bottom plate, and FIG. 6 is another modification of the spiral bottom plate. FIG. 7 is a bottom view showing still another modification of the spiral bottom plate, FIG. 8 is a front view of the spiral bottom plate shown in FIG. 7, and FIG. 9 is a bottom view showing still another modification of the spiral bottom plate. 10, FIG. 10 is a front view of the spiral bottom plate shown in FIG. 9, FIG. 11 is a partially omitted front view showing a second embodiment of the bottomed steel pipe pile of the present invention, and FIG. 12 is the third embodiment. FIG. 13 is a partially omitted front view showing the fourth embodiment, FIG. 14 is a partially omitted front view showing the fifth embodiment, and FIG. 15 is the sixth embodiment. The FIG. 16 to FIG. 18 are partial front views showing modified examples of the tip portion of the bottomed steel pipe pile shown in FIG. 14 or FIG. 15, and FIG. 19 to FIG. 12 or 13 is a partially omitted front view showing a modified example of the bottom-pipe type steel pipe pile shown in FIG. 12, FIG. 23 to FIG. 26 are bottom-pipe type steel pipe piles shown in FIG. FIG. 27 is a graph showing the relationship between pile head load and settlement amount for testing the effect of a pile having a spiral bottom plate provided with a peripheral wall, FIG. These are the front views which abbreviate | omitted one part which shows one Example of the conical multi-blade type steel pipe pile which is the 2nd aspect of this invention.
[0027]
The bottomed steel pipe pile of the present embodiment shown in FIG. 1 has a steel pipe 10 having a diameter of, for example, about 165φ cut out spirally along the outer periphery of the steel pipe substantially over one circumference, and along the cutout part. A spiral bottom plate 20 having a diameter of about 5 to 6 times the diameter of the steel pipe 10 and serving as an excavating blade is fixed by welding or the like.
[0028]
As shown in FIG. 2, the spiral bottom plate 20 is provided with an incision in a radial direction reaching the center thereof in an annular disk having a diameter of about 5 to 6 times the diameter of the steel pipe 10, and through the incision. It is formed by bending an annular disk so as to follow the front end surface of the steel pipe 10 that is notched in a spiral shape.
[0029]
The spiral bottom plate 20 is provided with a closing plate 21 that closes a gap between the start end and the end thereof, and a sand entry hole 22 that allows entry of the earth and sand into the steel pipe 10 is provided at the center thereof. In addition, a substantially trapezoidal leading member 23 that is fixed so as to cross the earth and sand entrance hole 22 and protrudes in the propulsion direction of the steel pipe 10 is provided at the center of the spiral bottom plate 20. The leading member 23 digs into the ground prior to the spiral bottom plate 20 during rotation propulsion, positions the spiral bottom plate 20 with respect to the ground, and prevents rotational misalignment of the spiral bottom plate 20. There is also a type in which the earth and sand entrance hole 22 is closed by the leading member 23.
[0030]
Next, a foundation construction method for constructing, for example, a two-story residential foundation on ultra-soft ground having an N value of less than 10 using the bottomed steel pipe pile of the first embodiment shown in FIG. 1 will be described. .
[0031]
The bottomed steel pipe pile shown in FIG. 1 is erected on the soft ground on which the foundation is to be constructed, and its upper end is attached to a rotary push-in drive device (not shown), and the steel pipe 10 is pushed into the ground while rotating by the drive device. Then, first, the leading member 23 bites into the ground, and the spiral bottom plate 20 is positioned with respect to the ground. Next, the spiral bottom plate 20 and the leading member 23 as a digging blade excavate and soften the earth and sand in the propulsion direction of the steel pipe 10, while extruding the earth and sand to the side portion of the steel pipe 10 and without shaking, the steel pipe 10 is not in the ground. It is rotated and propelled by earth removal.
[0032]
When the spiral bottom plate 20 is propelled into the ground by about 5 to 6 m from the ground surface, the drive of the rotary push-in driving device is stopped. The location where the spiral bottom plate 20 is located is consolidated by the earth and sand of the upper layer, and does not have the ground strength enough to support the pile, but has a little more ground strength than the ground surface portion.
[0033]
The load of the building is transmitted from the steel pipe 10 to the spiral bottom plate 20, and further transmitted from the spiral bottom plate 20 to the ground having strength in the deep formation located below the spiral bottom plate 20. At this time, since the spiral bottom plate 20 is formed to have a diameter five to six times the diameter of the steel pipe 10, the reaction force from the ground acting on the spiral bottom plate is received only in the case of the steel pipe 10. Compared to the case of the reaction force of 1/25 to 1/36. In other words, the load of the building is dispersed to about 1/25 to about 1/36 as compared with the case where it is supported by the steel pipe 10 alone, and transmitted to the strong ground located below.
[0034]
Therefore, without embedding bottom-pipe steel pipe piles up to the deep layer located below the soft ground, it is embedded in the soft ground as if it is floating, so that it is possible to reliably prevent uneven settlement and make the building extremely soft. Can be supported on the ground.
[0035]
In addition, a bending moment acts on the spiral bottom plate 20 due to a vertical reaction force from the ground. However, since the spiral bottom plate 20 is fixed to the tip surface of the steel pipe 10, it does not act on the steel pipe 10 and is vertical. It is only the compressive stress in the direction, and it is not necessary to make the steel pipe 10 thick to withstand the bending moment.In addition, the following formula is generally used as an example of the calculation formula for calculating the bearing capacity of the pile when the pile body is rotationally embedded at a predetermined depth,
[Expression 1]
Ra = safety factor 1/3 × (coefficient 30 × N value × tip projected area)
It becomes. When the spiral wing at the tip of the pile arrives at the ground at a predetermined depth, a machine that rotates the pile body is a method for managing whether or not the N value of the ground is greater than the N value at the time of bearing capacity calculation. Since the rotation resistance torque value graph of the motor and the N value graph of the ground survey show approximate values, the rotation resistance torque value at the time of pile construction is recorded, and the ground at the tip of the pile is greater than the N value of the predetermined ground It is possible to manage whether or not the pile has obtained the design support force of the pile calculated from the N value.
[0036]
3 and 4 show a modified example of the spiral bottom plate 20 shown in FIGS. 1 and 2. Excavation blades 24 and 24 having stepped blades are provided on the spiral bottom plate 20 a, and It extends in the diameter direction from the center and is fixed so as to be inclined by 40 ° to 45 ° with respect to the bottom surface of the spiral bottom plate 20.
[0037]
As with the leading member 23, the excavating blade 24 digs into the ground prior to the spiral bottom plate 20 to position the spiral bottom plate 20 with respect to the ground when rotating and propulsion, thereby rotating the rotational bottom of the spiral bottom plate 20. Then, after the spiral bottom plate 20 bites into the ground, the earth and sand in the propulsion direction of the steel pipe 10 are softened by excavation together with the spiral bottom plate 20. Further, the excavating blade 24 becomes a reinforcing rib that reinforces the spiral bottom plate 20. Therefore, the helical bottom plate 20 can withstand a bending moment due to a reaction force from the ground without setting the wall thickness to be thick.
[0038]
FIG. 5 shows another modification of the spiral bottom plate 20 shown in FIGS. According to this, the peripheral wall 25 is being fixed by fixing means, such as welding, along the lower surface periphery of the spiral bottom plate 20b. After embedding the bottomed-type steel pipe pile, the peripheral wall 25 is compacted so that the earth and sand on the bottom surface side of the spiral bottom plate 20b do not escape (restrained so as to be wrapped), thereby increasing the holding power of the earth and sand. The height of the peripheral wall 25 is set to about 30 mm to 50 mm. Such a range is set because if the height of the peripheral wall 25 is lower than 30 mm, a sufficient consolidation effect by the peripheral wall 25 cannot be obtained, and if the height of the peripheral wall 25 is higher than 50 mm, it is said to be soft ground. This is because a large resistance is not desirable when propelling the ground into the ground, and an improvement in the consolidation effect cannot be expected so much. It should be noted that depending on the condition of the ground, it may be slightly lower than 30 mm or higher than 50 mm.
[0039]
FIG. 6 shows a modification in which the peripheral wall 25a is formed integrally with the spiral bottom plate 20 by plastic processing such as press working of a steel plate, for example. In this case, the fixing step such as welding can be omitted as compared with the spiral bottom plate 20 shown in FIG. 5, and the peripheral wall 25a can be formed at the same time as the spiral bottom plate 20 is formed, thereby greatly reducing the processing cost. It becomes possible to plan. Then, as shown in FIGS. 7 to 10, by forming an embossed portion 20c which is an uneven portion on the spiral bottom plate 20, the bending strength of the spiral bottom plate 20 is further improved by the embossed portion 20c and the peripheral wall 25a. Can be made. In other words, even if the thickness of the spiral bottom plate 20 is set to be thinner than that shown in FIG. 5, it can sufficiently withstand the bending force caused by the reaction force from the ground. The number, shape, and the like of the embossed portion 20c are not limited to the embodiments shown in FIGS. In short, as long as the bending strength of the spiral bottom plate 20 is improved, it is not limited to the one shown in FIGS.
[0040]
Even when a steel pipe pile provided with peripheral walls 25 and 25a along the lower surface periphery of the spiral bottom plate 20 is rotated and propelled to an ultra-soft ground having an N value of less than 10, for example, a foundation for a two-story house is constructed. In the same manner as the steel pipe pile shown in FIG. 1, the steel pipe 10 is pushed into the ground while being rotated by the rotation pushing drive device. Thereby, a steel pipe pile is embed | buried in a super-soft ground to predetermined depth (depth of about 5m thru | or 6m from the ground surface). At this time, the peripheral walls 25 and 25a are consolidated so that the earth and sand on the bottom surface side (lower side) of the spiral bottom plate 20b do not escape (restrained so as to be wrapped). Therefore, the building can be supported on the very soft ground by the consolidation effect by the peripheral walls 25 and 25a and the support pressure by the spiral bottom plate 20.
[0041]
FIG. 11 shows a second embodiment of the bottomed steel pipe pile of the present invention.
[0042]
According to the second embodiment, the tip of the short tube 11 having a diameter of about 165φ is spirally cut out, and the tip of the cut short tube 11 is cut to 5 to 6 times the diameter of the short tube 11. A spiral bottom plate 30 having a diameter of about double is fixed. Then, a steel pipe 12 having an outer diameter that matches the inner diameter of the opening is fitted into the upper end opening of the short pipe 11 and fixed by joining means such as welding. A female screw is formed on the inner periphery of the upper end opening of the short tube 11 and a male screw is formed on the outer periphery of the tip of the steel tube 12 so that the steel tube 12 is screwed into the upper end opening of the short tube 11. May be.
[0043]
A trapezoidal leading member 31 that protrudes in the propulsion direction of the steel pipe 12 is provided at the center of the spiral bottom plate 30, as in the spiral bottom plate 20 of FIGS. 1 and 2. The leading member 31 digs into the ground prior to the spiral bottom plate 30 to position the spiral bottom plate 30 with respect to the ground during rotation propulsion, thereby preventing rotational misalignment of the spiral bottom plate 30.
[0044]
Although not shown, the spiral bottom plate 30 is provided with a closing plate that closes the gap between the starting end and the terminal end, and allows the entrance of earth and sand into the short tube 11 and the steel tube 12 at the center. There is a case where the earth and sand entering hole is provided and a case where the earth and sand entering hole is closed.
[0045]
In the case of the bottomed steel pipe pile shown in FIG. 11 as well, as in the case of the bottomed steel pipe pile shown in FIG. 1, it is embedded in the soft ground by a rotational push drive device, and the spiral bottom plate 30 is about 5 m to 6 m from the ground surface. This embedding is stopped when propelled inside.
[0046]
The load of the building is transmitted from the steel pipe 12 and the short pipe 11 to the spiral bottom plate 30 and further transmitted from the spiral bottom plate 30 to the ground having strength in a deep formation located below. At this time, since the spiral bottom plate 30 is formed to have a diameter 5 to 6 times the diameter of the short tube 11, the reaction force from the ground acting on the spiral bottom plate 30 is only when the steel tube 12 is used. Compared to the reaction force of the receiving ground, it is about 1/25 to 1/36 per unit area. In other words, the load of the building is dispersed to about 1/25 to about 1/36 as compared with the case where it is supported only by the steel pipe 12, and transmitted to the strong ground located below.
[0047]
According to the bottomed steel pipe pile of the second embodiment, in addition to the same effect as the case of the bottomed steel pipe pile of the first embodiment, the short pipe 11 and the steel pipe 12 to which the helical bottom plate 30 is fixed are provided. By transporting to a construction site in a separated state and joining both at the construction site, transportation to a narrow construction site becomes easy.
[0048]
The helical bottom plate 30 of the second embodiment can also be provided with a digging blade 24 as shown in FIGS. 3 and 4 and a peripheral wall 25 as shown in FIGS.
[0049]
FIG. 12 shows a third embodiment of the expanded steel pipe pile of the present invention.
[0050]
According to the third embodiment, the bottom plate 42 provided with the excavating blades 41, 41 is fixed to the tip of the steel pipe 13 having a diameter of about 165φ, and the diameter of the steel pipe 13 is fixed to the outer periphery on the tip side of the steel pipe 13. A spiral wing 40 of approximately one turn having a diameter of about 5 to 6 times is fixed.
[0051]
Also in the case of the bottom-pipe steel pipe pile shown in FIG. 12, when the steel pipe 13 is rotationally driven by the rotation push drive device, the excavation blade 41 softens the excavation of the ground while the steel pipe 13 is embedded in the soft ground, and the spiral blade The embedding is stopped when 40 is propelled into the ground by about 5 to 6 m from the ground surface.
[0052]
The load of the building is transmitted from the steel pipe 13 to the spiral wing 40 and further transmitted from the spiral wing 40 to the ground having strength in a deep formation located below the spiral wing 40. At this time, since the spiral wing 40 is formed to have a diameter 5 to 6 times the diameter of the steel pipe 13, the reaction force from the ground acting on the spiral wing 40 is received only in the case of the steel pipe 13. Compared to the reaction force of the ground, it is about 1/25 to 1/36 per unit area. In other words, the load of the building is dispersed to about 1/25 to about 1/36 as compared with the case where it is supported by the steel pipe 13 alone, and transmitted to the strong ground located below.
[0053]
Therefore, in the same way as the bottomed steel pipe pile of the first embodiment, without embedding the bottomed steel pipe pile to the deep formation located below the soft ground, it is embedded in a state that is floating in the soft ground. The structure can be supported on ultra-soft ground by preventing uneven settlement.
[0054]
FIG. 13 shows a fourth embodiment of the bottomed steel pipe pile of the present invention.
[0055]
According to the fourth embodiment, the bottom plate 52 provided with the excavating blade 51 is fixed to the tip of the short tube 14 having a diameter of about 165φ, and the short tube 14 is disposed on the outer periphery of the intermediate portion in the axial direction of the short tube 14. A spiral wing 50 of approximately one turn having a diameter of about 5 to 6 times the diameter of the spiral wing 50 is fixed. And the steel pipe 15 which has a diameter of about 90 (phi)-about 100 (phi) is connected to the upper end of the short pipe 14 with joining means, such as welding.
[0056]
Also in the case of the bottom-pipe steel pipe pile shown in FIG. 13, when the steel pipe 15 is rotationally driven by the rotary push-in driving device, the short pipe 14 and the steel pipe 15 are embedded in the soft ground while the excavation blade 51 softens the ground. The embedding is stopped when the spiral wing 50 is propelled into the ground by about 5 to 6 m from the ground surface.
[0057]
The load of the building is transmitted from the steel pipe 15 and the short pipe 14 to the spiral wing 50, and further transmitted from the spiral wing 50 to the ground having strength in a deep formation located below the spiral wing 50. At this time, since the spiral wing 50 is formed to have a diameter of about 5 to 6 times the diameter of the short pipe 14, the reaction force from the ground acting on the spiral wing 50 is the short pipe 14, the steel pipe. Compared to the reaction force of the ground received at 15, it is about 1/25 to about 1/36 per unit area. In other words, the load of the building is distributed from about 1/25 to about 1/36 as compared with the case where only the short pipe 14 and the steel pipe 15 are supported, and transmitted to the strong ground located below. To come.
[0058]
Therefore, in the same way as the bottomed steel pipe pile of the first embodiment, without embedding the bottomed steel pipe pile up to the deep formation located below the soft ground, it is embedded in a state as if floating in the soft ground. The structure can be supported on ultra-soft ground by preventing uneven settlement.
[0059]
Moreover, the short pipe 14 and the steel pipe 15 which fixed the helical wing | blade 50 are conveyed to a construction site in the state isolate | separated, and conveyance to a narrow construction site becomes easy by joining both in a construction site.
[0060]
FIG. 14 shows a fifth embodiment of the bottomed steel pipe pile of the present invention.
[0061]
According to the fifth embodiment, there is provided approximately one winding spiral blade 61 for excavation having a diameter of about 2 to 3 times the diameter of the steel pipe 16 on the outer periphery of the tip of the steel pipe 16 having a diameter of about 165φ. On the outer peripheral surface of the steel pipe 16 that is a predetermined distance above the excavating spiral blade 61 in the axial direction, there is provided a substantially one-turn spiral blade 60 having a diameter of about 5 to 6 times the diameter of the steel pipe 16. .
[0062]
Also in the case of the bottom-pipe steel pipe pile shown in FIG. 14, when the steel pipe 16 is rotationally driven by the rotary push-in driving device, the excavating spiral blade 61 softens the ground excavating and the steel pipe 16 is embedded in the soft ground and spiraled. The embedding is stopped when the wing 60 is propelled into the ground by about 5 to 6 m from the ground surface.
[0063]
The load of the building is transmitted from the steel pipe 16 to the spiral wing 60, and further transmitted from the spiral wing 60 to the ground having strength in the deep formation located below the spiral wing 60. At this time, since the spiral wing 60 is formed to have a diameter five to six times the diameter of the steel pipe 16, the reaction force from the ground acting on the spiral wing 60 is received only in the case of the steel pipe 16. Compared to the reaction force of the ground, it is about 1/25 to 1/36 per unit area. In other words, the load of the building is distributed to about 1/25 to 1/36 as compared with the case where it is supported by the steel pipe 16 alone, and is transmitted to the strong ground located below.
[0064]
Therefore, in the same way as the bottomed steel pipe pile of the first embodiment, without embedding the bottomed steel pipe pile to the deep formation located below the soft ground, it is embedded in a state that is floating in the soft ground. The structure can be supported on ultra-soft ground by preventing uneven settlement.
[0065]
Further, since the reaction force (ground resistance) from the ground is received not only by the spiral blade 60 but also by the drilling spiral blade 61, the load applied to the spiral blade 60 is reduced by the load received by the drilling spiral blade 61. can do. In other words, since the reaction force (ground resistance) from the ground is distributed and received by the spiral blade 60 and the excavation spiral blade 61, the thickness of the spiral blade 60 can be set thin. . In addition, the excavation efficiency can be improved by excavating with two blades.
[0066]
FIG. 15 shows a sixth embodiment of the present invention.
[0067]
According to the sixth embodiment, approximately one winding spiral blade 71 for excavation having a diameter that is about 2 to 3 times the diameter of the short tube 17 on the outer peripheral surface of the short tube 17 having a diameter of about 165φ. On the outer circumferential surface of the short tube 17 that is a predetermined distance above the excavating spiral blade 71 in the axial direction, and has a diameter that is approximately 5 to 6 times the diameter of the short tube 17, and has approximately one turn. 70 is provided. A steel pipe 18 having a diameter of about 90 to 100 φ is connected to the upper end of the short pipe 17 by a joining means such as welding.
[0068]
Also in the case of the bottom-pipe steel pipe pile shown in FIG. 15, when the steel pipe 18 is rotationally driven by the rotary push-in driving device, the excavating spiral blade 71 softens the ground while excavating and softening the short pipe 17 and the steel pipe 18 in the soft ground. Implantation is stopped when the spiral wing 70 is propelled into the ground by about 5 to 6 m from the ground surface.
[0069]
The load of the building is transmitted from the steel pipe 18 and the short pipe 17 to the spiral wing 70, and further transmitted from the spiral wing 70 to the ground having strength in a deep formation located below the spiral wing 70. At this time, since the spiral wing 70 is formed to have a diameter 5 to 6 times the diameter of the short tube 17, the reaction force from the ground acting on the spiral wing 70 is generated by the steel pipe 18. Compared to the case of reaction force, the ratio is about 1/25 to about 1/36 per unit area. In other words, the load of the building is dispersed to about 1/25 to about 1/36 as compared with the case where it is supported by the steel pipe 18 alone, and transmitted to the strong ground located below.
[0070]
Therefore, in the same way as the bottomed steel pipe pile of the first embodiment, without embedding the bottomed steel pipe pile to the deep formation located below the soft ground, it is embedded in a state that is floating in the soft ground. The structure can be supported on ultra-soft ground by preventing uneven settlement.
[0071]
Further, since the reaction force (ground resistance) from the ground is received not only by the spiral blade 70 but also by the drilling spiral blade 71, the load applied to the spiral blade 70 is reduced by the load received by the drilling spiral blade 71. can do. In other words, since the reaction force (ground resistance) from the ground is distributed and received by the spiral blade 70 and the excavation spiral blade 71, the thickness of the spiral blade 70 can be set thin. . In addition, the excavation efficiency can be improved by excavating with two blades.
[0072]
Furthermore, the short pipe 17 and the steel pipe 18 to which the spiral wing 70 is fixed are transported to the construction site in a separated state, and both are joined at the construction site, so that the transport to a narrow construction site is facilitated.
[0073]
In the fifth and sixth embodiments shown in FIGS. 14 and 15, as shown in FIG. 16, a pair of excavating blades 80, 80 may be provided at the tips of the steel pipe 16 and the short pipe 17. As shown in FIGS. 17 and 18, a bottom plate 81 is provided at the tip of the steel pipe 16 and the short tube 17, and a trapezoidal excavation blade 82 is provided on the bottom plate 81, or a blade height is formed on the center side of the bottom plate 81. Excavation blades 83, 83 having a high height may be provided.
[0074]
FIG. 19 is a modified example of the bottomed steel pipe pile shown in FIG. 1, and triangular reinforcing ribs 26 are provided on the upper surface of the spiral bottom plate 20 at the joint portion with the steel pipe 10. Thereby, even if the thickness of the spiral bottom plate 20 is set thin, it is possible to withstand a bending moment due to a reaction force from the ground.
[0075]
FIG. 20 is a modification of the bottom-expanded steel pipe pile shown in FIG. 11, and triangular reinforcing ribs 32 are provided at the joint portion with the short pipe 11 on the upper surface of the spiral bottom plate 30.
[0076]
FIG. 21 is a modified example of the bottomed steel pipe pile shown in FIG. 12, and triangular reinforcing ribs 43 are provided at the joint portion with the steel pipe 13 on the upper surface of the spiral blade 40.
[0077]
FIG. 22 is a modified example of the bottomed steel pipe pile shown in FIG. 13, and triangular reinforcing ribs 53 are provided on the upper surface of the spiral blade 50 at the joint portion with the short pipe 14.
[0078]
In addition, you may make it provide the reinforcing ribs 43 and 53 as shown in FIG. 21, FIG. 22 on the upper surface of the helical wings 60 and 70 shown in FIG.
[0079]
Further, in the embodiment shown in FIGS. 12 to 15, a plurality of spiral blades 40, 50, 60, 70 are provided on the outer peripheral surfaces of the steel pipes 13, 15, 16, 18 at appropriate intervals along the axial direction. You may do it.
[0080]
Moreover, you may provide the surrounding wall 25 as shown in FIG. 5 along the lower surface periphery of the spiral wings 40, 50, 60, and 70 shown in FIGS.
[0081]
In the case where a plurality of spiral blades 40, 50, 60, 70 are provided on the steel pipes 13, 15, 16, 18, not only the lowermost spiral blades 40, 50, 60, 70, but also other spirals. You may make it provide the surrounding wall 25 in the wing | blade 40, 50, 60, 70, respectively.
[0082]
FIGS. 23 to 26 show still another modified example of the bottomed steel pipe pile shown in FIGS. 12 to 15. For example, the spiral blades 40, 50, 60, and 70 are formed by plastic processing such as press working of a steel plate. The case where the surrounding wall 25b is integrally formed along the lower surface periphery of is shown. As with the peripheral walls 25 and 25a shown in FIGS. 5 and 6, the peripheral wall 25b allows the earth and sand on the bottom side (lower side) of the spiral wings 40, 50, 60, and 70 to escape after the bottomed steel pipe piles are buried. It is compacted in such a way that it is constrained (restrained so as to be wrapped and consolidated), and the holding power of earth and sand is increased.
[0083]
By forming the embossed portion 20d which is an uneven portion on the spiral blades 40, 50, 60 and 70, the bending strength of the spiral blades 40, 50, 60 and 70 is further improved by the embossed portion 20d and the peripheral wall 25b. Can be made.
[0084]
The steel pipe pile provided with the peripheral wall 25b along the lower surface periphery of the spiral wing 40 (50, 60, 70) is rotated and propelled to an ultra-soft ground having an N value of less than 10, for example, a foundation for a two-story house 1 is constructed, the steel pipe 13 (15, 16, 18) is pushed into the ground while being rotated by the rotary pushing drive device, similarly to the steel pipe pile shown in FIG. Thereby, a steel pipe pile is embed | buried in a super-soft ground to predetermined depth (depth of about 5m thru | or 6m from the ground surface). At this time, the peripheral wall 25b is consolidated so that earth and sand on the bottom side (lower side) of the spiral blades 40, 50, 60, and 70 do not escape (restraint so as to be wrapped). Therefore, the building can be supported on the very soft ground by the consolidation effect by the peripheral wall 25b and the support pressure by the spiral blades 40, 50, 60, and 70.
[0085]
FIG. 27 is a graph showing a loading test result of the steel pipe pile shown in the above example, which was carried out based on the Japan Geotechnical Society standard (JSF1821). The vertical axis represents the pile settlement (mm), and the horizontal axis represents the pile head load (tons).
[0086]
In this loading test, first, four reaction force piles are embedded around the test pile, the first beam is bridged between the reaction force piles, and the first beam is crossed over the test pile between the first beams. Prepare a jack (100 tons) between the second beam and the head of the test pile, and then drive the jack through the first and second beams. While a pulling force was applied to the reaction force pile, a pressing force as a reaction force of the pulling force was applied to the head of the test pile.
[0087]
The ground subjected to the above load test was an ultra-soft ground having an N value of about 3. The amount of settlement was measured using an electric resistance measuring instrument. The test piles used for the loading test are as follows.
[0088]
Test pile 1 Pile of the type shown in FIG. 14 (steel pipe diameter 114.3φ, upper spiral wing outer diameter 600φ, lower spiral wing outer diameter 250φ, wing distance 1.2 m)
Test pile 2 A pile of the type shown in FIG. 14 in which the interval between the spiral wings is reduced by half (steel pipe diameter 114.3φ, upper spiral wing outer diameter 600φ, lower spiral wing outer diameter 250φ, distance between blades 0.6m)
Test pile 3 Pile of the type shown in FIG. 24 (short pipe diameter 160φ, steel pipe diameter 110φ, spiral wing outer diameter 600φ)
Test pile 4 Pile of the type shown in FIG. 12 (steel pipe diameter 114.3φ, spiral wing outer diameter 700φ)
Test pile 5 Pile of the type shown in FIG. 12 in which the outer diameter of the spiral wing is smaller than the test pile 4 (steel pipe diameter 114.3φ, spiral wing outer diameter 600φ)
Test pile 6 Pile of the type provided with the peripheral wall 25b shown in FIG. 23 (steel pipe diameter 114.3φ, spiral blade outer diameter 600φ, peripheral wall height 50mm)
Test pile 7 A pile of the type provided with the peripheral wall 25b shown in FIG. 23, wherein the outer diameter of the spiral blade is larger than that of the test pile 6 (steel pipe diameter 114.3φ, spiral blade outer diameter) 700φ, and the height of the peripheral wall is 35 mm).
[0089]
As a comparison, the same test was performed on a conventional steel pipe pile (pile with the outer diameter of the spiral wing set to 2 to 3 times that of the steel pipe). Sinking quickly, it became impossible to measure the amount of settlement.
[0090]
As is clear from the graph shown in FIG. 27, it was confirmed that all of the bottom-pipe steel pipe piles of the above examples were able to obtain a sufficient bearing force on the very soft ground (N value is about 3). For example, in the steel pipe pile shown in FIG. 24, the subsidence amount was about 130 mm to 140 mm for a load of 8 tons. And when a surrounding wall was provided, it was confirmed that the amount of subsidence is made smaller (a big supporting force is obtained) compared with the other pile which does not provide a surrounding wall. For example, the test pile 6 has a settling amount of about 100 mm for a 13 ton pile head load, and the test pile 7 has a settling amount of about 100 mm for a 15 ton pile head load. Combined with the pressure, it was confirmed that a larger bearing capacity can be obtained in the ultra-soft ground due to the consolidation effect of the peripheral wall.
[0091]
FIG. 28 shows an example of a conical multi-blade type steel pipe pile according to the second aspect of the present invention. For example, on the outer peripheral surface of a steel pipe 19 having a diameter of about 165φ along the axial direction thereof. Three spiral blades 90, 91, 92 are arranged at substantially equal intervals, and the outer diameter of the lowermost spiral blade 90 located in the vicinity of the lower end of the steel pipe 19 is set to 2 to 3 times the diameter of the steel pipe 19. The outer diameter of the spiral blades 91 and 92 arranged in the upper part from the spiral blade 90 is sequentially increased. The outer diameter of the spiral blade 92 located at the top is set to 5 to 6 times the diameter of the steel pipe 19. And each spiral wing | blade 90, 91, 92 is integrally formed with the surrounding wall 25c along the lower surface periphery.
[0092]
As with the peripheral walls 25, 25a, 25b shown in FIGS. 5 and 6, etc., the peripheral wall 25c prevents the sediment on the bottom side (lower side) of each spiral wing 90, 91, 92 from escaping after embedding the steel pipe pile. Thus, it is consolidated (restrained so as to be wrapped and consolidated) to increase the holding power of earth and sand.
[0093]
By forming the embossment which is an uneven | corrugated | grooved part in the spiral wing | blade 90, 91, 92, the bending strength of each spiral wing | blade 90, 91, 92 can further be improved with this embossed part and the surrounding wall 25c.
[0094]
Note that a bottom plate 100 is provided at the tip (lower end) of the steel pipe 19, and a trapezoidal leading member 101 for preventing rotation center deviation is provided on the bottom plate 100. A drilling blade may be provided instead of the leading member 101.
[0095]
A conical multi-blade steel pipe pile provided with a peripheral wall 25c along the lower peripheral edge of each spiral wing 90, 91, 92 is rotated and propelled to an ultra-soft ground having an N value of less than 10, for example, two stories In the case of constructing the foundation for the house, the steel pipe 10 is pushed into the ground while being rotated by the rotary push-in driving device, similarly to the steel pipe pile shown in FIG. Thereby, a steel pipe pile is embed | buried in a super-soft ground to predetermined depth (depth of about 5m thru | or 6m from the ground surface). At this time, each peripheral wall 25c is compacted so that the earth and sand on the bottom surface side (lower side) of the spiral blades 90, 91, 92 do not escape (restrained so as to be wrapped), so that the consolidation effect by the peripheral wall 25c and the spiral shape are achieved. The building can be supported on the very soft ground by the support pressure by the wings 90, 91, 92.
[0096]
Further, in addition to the vertical support pressure by the spiral blades 90, 91, 92, the wedge effect due to the conical shape works, and the support pressure in the oblique direction is also added, thereby obtaining a large support force.
[0097]
【The invention's effect】
As explained above, according to the bottomed steel pipe pile which is the first aspect of the present invention, the steel pipe or the like is provided with the spiral bottom plate and the spiral wing having a diameter of about 5 to 6 times its diameter. Therefore, even if it is an extremely soft ground having an N value of less than 10, it is possible to reliably support the building so as not to sink. Moreover, when constructing, just like a normal support pile, it is only necessary to propel the bottomed steel pipe pile into the ground, and its depth is about 5m to 6m. You don't have to take the trouble of excavating the ground while retaining soil and draining, like the construction method and apple concrete foundation method, or mixing and stirring the soil at the construction site with soil cement like the ground improvement column method. The construction cost can be greatly reduced. Furthermore, there is no risk of variations in quality unlike the ground improvement column method.
[0098]
In addition, by providing a peripheral wall around the bottom surface of the spiral bottom plate and spiral wing, when the steel pipe pile is rotated and propelled into the ground, the peripheral wall is restrained so as to enclose the soil below the spiral bottom plate and spiral wing. After the steel pipe piles are buried, the consolidation effect by the peripheral wall and the support pressure of the spiral bottom plate and spiral wings combine to support the building so that it does not sink even in extremely soft ground. Can do.
[0099]
Further, according to the conical multi-blade type steel pipe pile according to the second aspect of the present invention, a plurality of spiral wings are arranged at predetermined intervals on the outer peripheral surface of the steel pipe, and the lowermost spiral wing is provided. The outer diameter of the steel pipe is set to 2 to 3 times the diameter of the steel pipe so that the outer diameter gradually increases from the lowermost spiral wing according to the spiral wing arranged at the upper part. Since the peripheral wall is provided along the peripheral edge of the lower surface, the building can be surely supported by the support pressure by each spiral wing and the consolidation effect by each peripheral wall so as not to sink even in an extremely soft ground.
[Brief description of the drawings]
FIG. 1 is a partially omitted front view showing a first embodiment of a bottomed steel pipe pile according to the present invention.
2 is a perspective view of the spiral bottom plate of FIG. 1. FIG.
FIG. 3 is a front view showing a modified example of the spiral bottom plate.
4 is a perspective view of the spiral bottom plate of FIG. 3. FIG.
FIG. 5 is a perspective view showing another modification of the spiral bottom plate.
FIG. 6 is a perspective view showing another modification of the spiral bottom plate.
FIG. 7 is a bottom view showing still another modified example of the spiral bottom plate.
8 is a front view of the spiral bottom plate shown in FIG. 7. FIG.
FIG. 9 is a bottom view showing still another modified example of the spiral bottom plate.
10 is a front view of the spiral bottom plate shown in FIG. 9. FIG.
FIG. 11 is a partially omitted front view showing a second embodiment of the bottomed steel pipe pile of the present invention.
FIG. 12 is a partially omitted front view showing a third embodiment.
FIG. 13 is a partially omitted front view showing a fourth embodiment.
FIG. 14 is a partially omitted front view showing a fifth embodiment.
FIG. 15 is a partially omitted front view showing a sixth embodiment.
FIG. 16 is a partial front view showing a modification of the tip portion of the bottom expanded steel pipe pile shown in FIG. 14 or FIG. 15;
FIG. 17 is a partial front view showing a modification of the tip portion of the bottom expanded steel pipe pile shown in FIG. 14 or FIG. 15;
FIG. 18 is a partial front view showing a modification of the tip portion of the bottom expanded steel pipe pile shown in FIG. 14 or FIG. 15;
19 is a partially omitted front view showing a modified example of the bottomed steel pipe pile shown in FIG. 1. FIG.
20 is a partially omitted front view showing a modified example of the bottomed steel pipe pile shown in FIG.
21 is a partially omitted front view showing a modified example of the bottomed steel pipe pile shown in FIG.
22 is a partially omitted front view showing a modified example of the bottomed steel pipe pile shown in FIG.
23 is a partially omitted front view showing another modified example of the bottom-pipe type steel pipe pile shown in FIG. 12. FIG.
24 is a partially omitted front view showing another modified example of the bottom-pipe type steel pipe pile shown in FIG. 13; FIG.
FIG. 25 is a partially omitted front view showing another modified example of the steel pipe pile of the bottomed type shown in FIG. 14;
26 is a partially omitted front view showing another modified example of the bottom-pipe type steel pipe pile shown in FIG. 15;
FIG. 27 is a graph showing the relationship between pile head load and settlement amount for testing the effect of a pile having a spiral bottom plate provided with a peripheral wall.
FIG. 28 is a partially omitted front view showing an embodiment of a conical multi-blade type steel pipe pile according to the second aspect of the present invention.
[Explanation of symbols]
10, 12, 13, 15, 16, 18, 19 Steel pipe
11, 14, 17 Short tube
20, 30 Helical bottom plate
40, 50, 60, 70, 90, 91, 92 spiral wing
25, 25a, 25b, 25c
41, 51 drilling blade
61, 71 Spiral wing for excavation
23, 31 Leading member
26, 32, 43, 53 Reinforcing ribs

Claims (21)

A spiral bottom plate having a diameter of about 5 to 6 times the diameter of the steel pipe is fixed to the tip notch of the steel pipe with the tip cut into a spiral ;
An expanded bottom steel pipe pile , wherein the spiral bottom plate is formed with an uneven portion for increasing the bending strength of the spiral bottom plate . A spiral bottom plate having a diameter of about 5 to 6 times the diameter of the short tube is fixed to the tip notch portion of the short tube whose tip is notched in a spiral shape, and the upper end opening of the short tube is A steel pipe having an outer diameter that matches the inner diameter of the opening is fitted and fixed ,
An expanded bottom steel pipe pile , wherein the spiral bottom plate is formed with an uneven portion for increasing the bending strength of the spiral bottom plate .    The steel pipe pile according to claim 1 or 2, wherein a reinforcing rib is attached to an upper surface or a lower surface of the spiral bottom plate and a joint portion between the steel pipe or the short tube and the spiral bottom plate. An expanded bottom steel pipe pile.   The steel pipe pile according to any one of claims 1 to 3, wherein a leading member for preventing rotational misalignment is attached to a lower center of the spiral bottom plate.   The steel pipe pile according to any one of claims 1 to 4, wherein the spiral bottom plate is provided with a peripheral wall along a lower surface periphery thereof.   The steel pipe pile according to claim 5, wherein the spiral bottom plate and the peripheral wall are integrally formed. A spiral wing having a diameter of about 5 to 6 times the diameter of the steel pipe is fixed to the outer periphery on the tip side of the steel pipe with a bottom plate having a drilling blade or a leading member for preventing rotation misalignment at the tip. Become
An expanded bottom steel pipe pile , wherein the spiral wing is formed with an uneven portion for increasing the bending strength of the spiral wing . A helical wing having a diameter of about 5 to 6 times the diameter of the short tube is fixed to the outer periphery of the short tube to which the excavating blade or the bottom plate provided with a leading member for preventing rotation misalignment is fixed at the tip; and A steel pipe having a smaller diameter than the short pipe is connected to the upper end of the short pipe ,
An expanded bottom steel pipe pile , wherein the spiral wing is formed with an uneven portion for increasing the bending strength of the spiral wing . The steel pipe pile according to claim 7 or 8 , wherein the spiral wing is provided with a peripheral wall along a lower surface periphery thereof. The steel pipe pile according to claim 9 , wherein the spiral wing and the peripheral wall are integrally formed. A steel pipe pile according to any one of claims 7 to 10 , wherein a plurality of the spiral wings are arranged in the steel pipe at appropriate intervals along the axial direction thereof. Steel pipe pile. An outer peripheral surface of the steel pipe provided with a substantially one-turn excavation spiral blade having an outer diameter of about twice the diameter of the steel pipe on the outer peripheral surface of the distal end portion of the steel pipe, and placed at a predetermined distance above the excavation spiral blade in the axial direction. And a spiral wing having a diameter of about 5 to 6 times the diameter of the steel pipe ,
An expanded bottom steel pipe pile , wherein the spiral wing is formed with an uneven portion for increasing the bending strength of the spiral wing . An excavating blade or a bottom plate having a leading member for preventing rotational misalignment is fixed at the tip, and an approximately one-turn spiral blade for excavation having an outer diameter about twice the diameter of the steel pipe is provided on the outer peripheral surface of the tip of the steel pipe A spiral wing having a diameter of about 5 to 6 times the diameter of the steel pipe is provided on the outer peripheral surface of the steel pipe that is a predetermined distance above the excavating spiral wing in the axial direction ;
An expanded bottom steel pipe pile , wherein the spiral wing is formed with an uneven portion for increasing the bending strength of the spiral wing . The short pipe is provided with an approximately one-turn excavation spiral blade having an outer diameter of about twice the diameter of the short pipe on the outer peripheral surface of the tip of the short pipe, and a predetermined distance above the excavation spiral blade in the axial direction. A spiral wing having a diameter of about 5 to 6 times the diameter of the short tube is provided on the outer peripheral surface of the short tube, and a steel pipe having a smaller diameter than the short tube is connected to the upper end of the short tube ,
An expanded bottom steel pipe pile , wherein the spiral wing is formed with an uneven portion for increasing the bending strength of the spiral wing . An excavation blade or a spiral blade for excavation having an outer diameter approximately twice the diameter of the short tube on the outer peripheral surface of the short tube on the outer peripheral surface of the short tube, to which a bottom plate having a drilling blade or a leading member for preventing rotational misalignment is fixed at the tip A spiral wing having a diameter of about 5 to 6 times the diameter of the short tube is provided on the outer peripheral surface of the short tube spaced a predetermined distance above the excavating spiral blade in the axial direction, and the short tube A steel pipe smaller in diameter than the short pipe is connected to the upper end of the
An expanded bottom steel pipe pile , wherein the spiral wing is formed with an uneven portion for increasing the bending strength of the spiral wing . The steel pipe pile according to any one of claims 12 to 15 , wherein a reinforcing rib is attached to a joint portion between the steel pipe or the short pipe and the spiral wing on the upper surface or the lower surface of the spiral wing. An expanded bottom steel pipe pile characterized by The steel pipe pile according to any one of claims 12 to 16 , wherein a plurality of the spiral wings are arranged on the steel pipe at appropriate intervals along the axial direction thereof. Pile. A widened steel pipe pile according to any one of claims 12 to 17 , wherein the spiral wing located at least in the lowermost portion of the plurality of spiral wings is provided with a peripheral wall along a lower surface periphery. An expanded bottom steel pipe pile characterized by The steel pipe pile according to claim 18 , wherein the spiral wing and the peripheral wall are integrally formed. A plurality of spiral blades are arranged at appropriate intervals along the axial direction on the outer peripheral surface of a steel pipe to which a drill plate or a bottom plate having a leading member for preventing rotational misalignment is fixed at the tip. Among them, the outer diameter of the spiral wing arranged at the lowermost part is set to 2 to 3 times the diameter of the steel pipe, and the outer diameter is sequentially increased from the lowermost spiral wing to the spiral wing arranged at the upper part. A steel pipe pile characterized in that each spiral wing is provided with a peripheral wall along the periphery of the lower surface thereof, and has an uneven portion for increasing the bending strength of the spiral wing. . The steel pipe pile according to claim 20 , wherein the spiral wings and the peripheral wall are integrally formed.

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