JP3784773B2 - Foundation pile - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a foundation pile that can be buried in soft ground with no soil, no noise, and no vibration, and can maintain a sufficient supporting force after being buried.
[0002]
[Prior art]
As a foundation pile with spiral wings buried in soft ground with no soil, no noise, no vibration, for example, a closed pile with a pile body made of steel pipe closed and a pile pile with the tip opened An open type is known.
[0003]
The closed-type foundation pile with the closed tip is excellent in that after being embedded in the ground, the tip of the pile main body can receive the ground reaction force in addition to the spiral wing to ensure a sufficient supporting force. However, there is a problem that a large pressing force is required to push the pile body into the ground in order to push out the earth and sand for the volume of the pile body to the side surface side of the pile body when buried in the ground. In addition, although the earth and sand pushed out to the side of the pile main body generates the rotational propulsion reaction force of the spiral wing and the pile main body is propelled into the ground, the rotation of the tip spiral wing attached to the front side of the pile main body causes the pile to rotate. There is a problem that misalignment occurs at the tip of the main body. That is, there is a problem that the tip of the pile body is closed, there is resistance to biting into the ground, and the tip of the pile body is likely to move in the rotation direction of the tip spiral wing due to the rotation of the tip spiral wing.
[0004]
On the other hand, in the open-type foundation pile with the open end, when burying it in the ground, the soil for the volume of the pile body is taken into the inside from the opening of the end of the pile body, Although it is expected that the problems of foundation piles can be solved, there are actually the following problems. When the pile body is rotated during embedding in the ground, the spiral wings bite into the ground with half rotation of the pile body and propel the pile body into the ground, but the spiral wings press the earth and sand with the remaining half rotation, It works to push the earth and sand into the inside of the pile body from the opening at the tip of the pile, and as a result, the earth inside the pile body is pushed in more than the volume of the pile body, and the inside of the pile body is immediately closed by the earth and sand. . Therefore, in order to push the pile main body further into the ground, a large pressing force is required to push the pile main body into the ground in the same manner as the closed foundation pile. In the case of a silt layer with a soft N content of around 0 to 3 and a high water content, there is almost no resistance due to earth and sand, and no rotational propulsion is generated by spiral blades, making it long for foundation piles. It takes time. In other words, even if the pile body is rotated, the spiral wing merely scratches the soil with high water content around it, and rotation propulsion is not performed as in the case of rotating the spiral wing in the water, and idling is repeated. Therefore, it is necessary to leave the whole day and night and wait for the resistance of the earth and sand to recover, and then continue the foundation pile burial work. Furthermore, when the load test to confirm the safety of the pile after the tip of the pile body reaches the support layer, the design load can be supported, but considering the safety factor, it is twice the design load. When a load is applied, the settlement of the pile progresses, and when a load of 3 times is applied, only 75% to 80% of the load of this 3 times load can be supported. It has been found that power cannot be secured. The cause is presumed that the earth and sand slide and break due to the pressure acting on the ground from the lower part of the spiral wing, and this earth and sand penetrates into the inside from the tip opening of the pile body.
[0005]
The open-type foundation pile is expected to solve the problems of the closed-type foundation pile, but has various problems as described above.
[0006]
As shown in FIGS. 5 to 7, the tip portion of the steel pipe 50 having an open end is cut out along the spiral blade, and the notch end portion 51 has an outer diameter larger than the outer diameter of the steel pipe, The doughnut-shaped steel plate 52 having a diameter smaller than the inner diameter of the steel pipe is fixed by welding, and the earth and sand that has entered the steel pipe 50 at a position approximately 0.5 to 2.0 times the inner diameter of the steel pipe 50a from the tip of the steel pipe 50 is fixed. There has been proposed a steel pipe pile provided with an annular protrusion 53 for promoting blockage (see, for example, Patent Document 1).
[0007]
[Patent Document 1]
Japanese Patent Laid-Open No. 2001-146741 (page 8, FIGS. 4 and 10)
[0008]
[Problems to be solved by the invention]
However, in this proposed steel pipe pile, the problem is that the tip of the pile is efficiently embedded in the support layer where the ground is relatively hard, and the embedding (construction) until it reaches the support layer through the soft ground ) The speed was not considered a problem, and the burial speed was not the same as the closed foundation pile, which was not satisfactory.
[0009]
What is required as a foundation pile is that it is easy to embed in the ground (the burial speed is faster than that of a closed-type foundation pile) and that it can secure a sufficient bearing capacity after embedment. None of the foundation piles satisfied this requirement.
[0010]
The present invention has been made in view of the above circumstances, and provides a foundation pile that is easy to embed in the ground (the burial speed is higher than that of a closed-type foundation pile) and that can secure a sufficient support force after burying. For the purpose.
[0011]
[Means for Solving the Problems]
As a result of examining the problems of the above-mentioned open-type foundation pile, in order to promote the embedment promotion of the pile body into the ground, the tip of the pile body was opened, and the earth and sand for the volume of the pile body was transferred to the pile body. It is necessary to enter the pile body with the embedding and not to exceed the volume (the inner blockage should not be generated). It was found that it was necessary to prevent slippage of the earth and sand at the bottom of the spiral wing and prevent the earth and sand from entering (inflowing) from the tip of the pile body. The present inventor conducted earnest research to satisfy these requirements, and can satisfy these requirements by securely holding the sand and sand between the tip side surface of the pile body and the bottom surface of the tip spiral blade. The present invention has been found and the present invention has been made.
[0012]
That is, in the foundation pile of the present invention that achieves the above object, the tip of the pile body is between the bottom surface of the tip spiral wing that is the spiral wing located closest to the tip of the pile body and the outer peripheral surface on the tip side of the pile body. In order to hold the earth and sand, a predetermined length is projected from the tip spiral wing. More specifically, the tip of the pile body protrudes from the tip spiral wing, which is the spiral wing located closest to the tip of the pile body, by a predetermined length, thereby rotating the tip spiral by rotation of the tip spiral wing when the foundation pile is buried. The earth and sand pressed on the bottom surface of the wing are held between the bottom surface of the tip spiral wing and the outer peripheral surface on the tip side of the pile body and are not allowed to flow into the pile body from the opening.
[0013]
Pile construction is performed by transmitting the load and rotational force of the excavator from the top to the pile body. When the load and rotational force of the excavator is transmitted to the pile body, the pile tip protrusion rotates and the pile tip cross-sectional area Therefore, the pile body is propelled while allowing the sand to enter inside, and the spiral wing at the tip rotates to cut into the ground, and the pile body is pulled in with the ground strength due to the composition of the soil as the reaction force of rotation propulsion. Rotation is buried in the ground to generate rotation propulsion force of the pile body, while the earth and sand pressed by the bottom surface of the tip spiral blade is held by the tip side surface of the pile body, and the pile body from the opening at the tip of the pile body The internal blockage is prevented by not entering (inflowing) into the interior, and this promotes the rotation of the pile body. Moreover, after embedding the pile body, it becomes possible to consolidate the earth and sand between the bottom surface of the tip spiral wing and the tip side surface of the pile body, prevent slippage of the earth and sand and ensure a sufficient support force. .
[0014]
It is preferable to set the length of the tip of the pile body to protrude from the tip spiral wing, for example, about 1 to 2 times the diameter of the pile body. If the projecting length is less than 1 times the diameter of the pile body, the sediment flowing in the lower part of the tip spiral wing causes soil and sand that exceeds the volume of the pile body to flow into the pile body and the inside of the pile body is inside. The construction efficiency is lowered and the effect of preventing the core misalignment due to the protruding part is reduced, and after reaching the support layer, soil is held between the bottom surface of the tip spiral blade and the tip side of the pile body. It is difficult to consolidate, and if the protruding length exceeds twice the diameter of the pile body, it is possible to consolidate while holding the earth and sand, but the tip spiral wing is far away from the tip of the pile body, This is because the supporting force of the pile exhibits the supporting force by the sum of the bottom area of the spiral wing and the supporting layer, so that it is not necessary to have more than twice the diameter of the pile body.
[0015]
Moreover, it is preferable to set the outer diameter of a front-end | tip spiral blade to 2 to 3 times the diameter of a pile main body, for example. If the outer diameter of the tip spiral wing is less than twice the diameter of the pile body, the rotational propulsion force of the tip spiral wing is small and the area that receives the ground reaction force of the tip spiral wing is small, and sufficient support force is obtained. If the outer diameter of the tip spiral wing exceeds three times the diameter of the pile body, a large rotational force and pressing force may be required to damage the pile body when the tip spiral wing is bitten into a hard support layer. May end up.
[0016]
In addition, for example, two spiral wings are arranged on the outer peripheral surface of the pile body, one is a tip spiral wing, and the other one is 1. It is preferable that the upper spiral blade has an outer diameter larger than the outer diameter of the tip spiral blade arranged at an interval of 5 to 2 times. In this way, the upper spiral wing does not reach the silt layer even if the tip spiral wing enters the soft silt layer with a high water content and the tip thrust blade impinges on the ground without obtaining the rotational thrust. Sunk into the ground and gains rotational propulsion force, so the pile body can be propelled embedded in the ground, and even if the tip spiral wing passes through the silt layer and the upper spiral wing moves to the silt layer, The tip spiral wings can bite into the ground and get a rotational driving force. That is, it is possible to prevent a situation in which one of the spiral wings bites into the ground and the spiral wing idles in the ground and the rotational thrust cannot be obtained. Furthermore, when the rotary embedding is completed at a predetermined position of the support layer and the building load is applied to the tip of the pile, the load is transmitted to the ground by the blade bottom of the tip spiral blade and the upper spiral blade, and the two spiral blades Can exert a great support.
[0017]
Further, for example, a reinforcing plate can be provided along the outer peripheral surface of the tip protruding from the tip spiral blade of the pile body, and the excavating blade can be fixed to the reinforcing plate. If it does in this way, even if the front-end | tip of a pile main body approachs into the hard ground used as a support layer, there is no possibility of deform | transforming or being crushed by the pressure from a ground.
[0018]
Further, for example, a friction cut plate is provided along the inner peripheral surface of the tip portion protruding from the tip spiral wing of the pile body, the end portion of the friction cut plate is protruded from the tip end of the pile body, and the protruding end portion A cutting edge can be formed. If it does in this way, the opening area of the opening part of the front-end | tip of a pile main body will become narrow by the friction cut board (opening part will be narrowed), and the earth and sand which was excavated and softened by the cutting blade will enter the inside of a pile main body through an opening part. At this time, although the entry of the earth and sand is once suppressed, when the earth and sand pass through the friction cut plate, the earth enters the space wider than the opening, and the earth and sand thereafter moves smoothly in the pile body. In this specification, the friction cut plate does not eliminate friction between itself and the earth and sand, but once the inflow of earth and sand has been squeezed, it is released to release the earth and sand into the pile body. It means to contribute to smoothness.
[0019]
Further, the spiral wing disposed on the outer peripheral surface of the pile body is composed of the tip spiral wing, the upper spiral wing, and a plurality of auxiliary spiral wings, and the plurality of auxiliary spiral wings are shafts of the foundation pile. The auxiliary spiral wing closest to the upper spiral wing is spaced 1.5 times or twice as large as the outer diameter of the tip spiral wing upward from the upper spiral wing. And may have an outer diameter larger than the outer diameter of the upper spiral blade.
[0020]
Further, the outer diameter of each auxiliary spiral blade is constant so that the outer diameter of the auxiliary spiral blade closest to the upper spiral blade is the smallest and the outer diameter of the auxiliary spiral blade disposed at the top is the largest. The ratio can be increased.
[0021]
Moreover, at least one or more inner spiral wings may be provided on the inner peripheral surface of the pile body at a position about 1 to 2 times the diameter of the pile body from the opening. For example, it is preferable that one inner spiral blade is provided at the same position as the tip spiral blade.
[0022]
Furthermore, the connection pile which has an outer diameter larger than the outer diameter of the pile main body of this foundation pile can be connected with the base end of the said foundation pile.
[0023]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a perspective view showing an embodiment of the foundation pile of the present invention, FIG. 2 is a perspective view showing a modification of the foundation pile of FIG. 1 with a part omitted, and FIG. 3 is another embodiment of the foundation pile of the present invention. FIG. 4 is a partial cross-sectional view in which the tip spiral wing of the foundation pile of FIG. 3 is omitted.
[0024]
An embodiment of a foundation pile according to the present invention will be described with reference to FIG. The foundation pile 10 is an open-type foundation pile in which a plurality of excavation blades 13 are fixed to an opening end surface 12 at the tip (lower end) of a steel pipe pile main body 11 by welding or the like, and is wound around the outer peripheral surface of the pile main body 11. The tip spiral blade 14 and the upper spiral blade 15 are fixed by welding or the like.
[0025]
Specifically, a pile extending spirally upward along the outer peripheral surface of the pile body 11 with a position 16 away from the tip of the pile body 11 as far as the diameter (pile diameter) of the pile body 11 upward. A winding spiral blade 14 having an outer diameter approximately twice the diameter is fixed by welding or the like. In addition, the outer peripheral surface of the pile main body 11 is located at a position above the front spiral blade 14, that is, the outer peripheral surface position of the pile main body 10 that is 1.5 to 2 times the diameter (blade diameter) of the front spiral blade 14. A single upper spiral blade 15 having a diameter larger than the blade diameter and extending upward in a spiral manner is fixed by welding or the like.
[0026]
A space 17 is defined between the bottom surface of the tip spiral blade 14 and the outer peripheral surface on the tip side of the pile body 11 to hold the soil in a compacted state. In other words, the space 17 for holding the earth and sand in a compacted state is defined around the tip protruding portion 11a protruding from the tip spiral blade 14 of the pile body 11. When the pile body 11 is embedded in the ground, the space 17 compacts the earth and sand pressed by the bottom surface of the tip spiral blade 14 by the rotation of the tip spiral blade 14, and this becomes resistance of the tip spiral blade 14. While the rotational propulsion force of the main body 11 is generated, the pile main body 11 is prevented from being blocked by the earth and sand pressed by the bottom surface of the tip spiral blade 14 from entering (inflowing) into the opening end surface 12. In addition, the space 17 can consolidate the earth and sand even after the pile main body 11 is buried, and can prevent slippage of the earth and sand and ensure a sufficient supporting force.
[0027]
According to the foundation pile of the said Example, if the load and rotational force of an excavation machine are transmitted to the pile main body 11 from the upper part, the front-end | tip protrusion part 11a of the pile main body 11 will rotate, and the opening end surface 12 of the front-end | tip of the pile main body 11 will be interrupted. Since the area is small, the pile main body 11 is propelled while the sand is entering the inside, and the tip spiral blade 14 rotates so as to cut into the ground, and the pile main body 11 uses the strength of the ground due to the composition of the soil as the reaction force of the rotational propulsion. Rotating burial is performed in the ground. In this rotation propulsion, the earth and sand enters the inside of the pile body 11 from the opening end surface 12 of the pile body 11, because the earth and sand are consolidated and held in the space 17 (because the space 17 exhibits the ground holding force), the tip The earth and sand pressed by the bottom surface of the spiral blade 14 can be prevented from entering from the opening end face 12 (inhibition of unnecessary sand and sand can be prevented) and internal blockage by the earth and sand can be avoided. Can be promoted. Until the tip of the pile body 11 reaches the formation having a predetermined N value, the steel pipe is spun and rotated into the ground. During the rotational propulsion into the ground, the tip spiral wing 14 enters the soft silt layer with a high water content, and the tip propulsion wing 14 bites into the ground. If the upper spiral wing 15 located at an upper position 1.5 to 2 times the diameter of the spiral wing 14 is in another hard ground and does not reach the silt layer, the upper spiral wing 15 bites into the ground and rotates. Since the propulsive force is obtained, the pile main body 11 can be embeded and propelled in the ground without any trouble. And even if the tip spiral blade 14 passes through the silt layer and the upper spiral blade 15 moves to the silt layer, the tip spiral blade 14 can now bite into the ground and obtain a rotational driving force.
[0028]
After the foundation pile 10 is buried, the building load on the foundation pile 10 acts on the ground via the pile body 11, the tip spiral blade 14, the upper spiral blade 15, etc., while the pile body 11, the tip spiral blade 14, A ground reaction force acts on the upper spiral wing 15 and the like, and the building is firmly supported on the ground. At this time, although the pressing force acts on the earth and sand by the bottom surface of the tip spiral blade 14, the earth and sand is consolidated and held in the space 17 (the space 17 exerts the ground holding force), causing a sliding failure and causing the pile from the open end face 12. It does not enter the inside of the main body 11, and the supporting force can be maintained.
[0029]
FIG. 2 shows a modification of the foundation pile 10 shown in FIG. 1. In the foundation pile 10 a of this modification, the outer peripheral surface of the pile main body 11 that defines the space 17 is made of a steel pipe as a reinforcing plate. The pipe 18 is fixed by welding or the like, and the pile body 11 and the outer pipe 18 are concentric. Moreover, in the foundation pile 10a, the three excavation blades 13 are fixed to the opening end surface of the outer tube 18 by welding or the like at a predetermined interval in the circumferential direction instead of the opening end surface 12 of the pile body 11. If the excavating blade 13 is attached to the opening end surface of the outer pipe 18 having a short length instead of the opening end surface 12 of the pile body 11, the excavating blade 13 can be easily attached.
[0030]
In the case of the foundation pile 10a of the modified example, even if the tip of the pile body 11 is in the hard ground, the outer peripheral surface of the pile body 11 is protected by the outer tube 18, and there is no possibility of being crushed by the pressure of the ground.
[0031]
Next, another embodiment of the foundation pile according to the present invention will be described with reference to FIGS. In the figure, the same parts as those shown in FIG.
[0032]
In the foundation pile 10b of the present embodiment, a tubular friction cut plate 19 having a short length along the inner peripheral surface is fixed to the opening 12a at the tip of the pile body 11 by welding or the like. The friction cut plate 19 is concentric. The friction cut plate 19 is thicker than the thickness of the steel pipe constituting the pile main body 11, and the end protrudes from the tip of the pile main body 11 and is formed on the cutting blade 20.
[0033]
When embedding the foundation pile 10b in the ground, the cutting blade 20 excavates and softens the earth and sand, and the pile body 11 passes through the opening 12a whose opening area (the earth and sand inflow port) is reduced by the friction cut plate 19. It will enter the inside of. When the earth and sand enters the pile main body 11, the friction cut plate 19 once suppresses the entry of the earth and sand (squeezing the flow of earth and sand), but when the earth and sand passes through the friction cut plate 19, it is wider than the opening 12 a. It will enter the space, and the earth and sand will move smoothly in the pile body 11 thereafter. In other words, once the aperture 12a is squeezed, the inflow of excess earth and sand (the earth and sand that causes internal blockage) is prevented, the friction between the earth and the inner wall of the pile body 11 is reduced, and the pile body 11 Smooth the flow of earth and sand inside.
[0034]
That is, according to the foundation pile 10 b, in combination with the effect of the space 17 defined between the bottom surface of the tip spiral blade 14 and the outer peripheral surface of the tip body 11, The flow becomes smooth, and it becomes possible to improve the efficiency of burying work in the ground.
[0035]
In addition, the friction cut board 19 will also reinforce the front-end | tip of the pile main body 11 similarly to the outer tube | pipe 18 of FIG.
[0036]
In the embodiment shown in FIGS. 1 to 4, the case where one upper spiral blade 15 is provided in addition to the tip spiral blade 14 is shown, but the upper spiral blade 15 may not be provided, and the upper spiral blade 15 may be omitted. Two or more may be provided.
[0037]
Next, still another embodiment of the foundation pile according to the present invention will be described with reference to FIGS. FIG. 12 shows a perspective view of the tip spiral blade 14, and FIG. 13 shows a bottom view of the tip spiral blade 14. As shown in FIG.12 and FIG.13, the excavation blade 14b is provided in the front end 14a of the front-end | tip spiral blade 14 by welding etc. As shown in FIG. By providing the excavating blade 14b in this way, the rotational driving force of the pile body can be improved and smooth construction can be performed. In addition, as shown in FIG. 12, by chamfering the front end 14a of the tip spiral blade 14 to form an inclined surface 14c, the rotational driving force of the pile body can be further improved and smoother construction can be performed.
[0038]
Next, still another embodiment of the foundation pile according to the present invention will be described with reference to FIG. As shown in FIG. 8, in the foundation pile 10c of this modification, the spiral wings arranged on the outer peripheral surface of the pile body 11 are the tip spiral wing 14, the upper spiral wing 15, and the two auxiliary spiral wings 30a and 30b. It is configured. The two auxiliary spiral blades 30a and 30b are arranged at regular intervals in the axial direction of the pile body 11 of the foundation pile 10c, and the auxiliary spiral blade 30a closest to the upper spiral blade 15 is located upward from the upper spiral blade 15. The tip spiral blade 14 is arranged with an interval of 1.5 to 2 times the outer diameter of the tip spiral blade 14 and has an outer diameter larger than the outer diameter of the upper spiral blade. Further, the auxiliary spiral blades 30a and 30b are arranged so that the outer diameter of the auxiliary spiral blade 30a closest to the upper spiral blade 15 is the smallest and the outer diameter of the auxiliary spiral blade 30b disposed at the top is large. It is increasing at a certain rate. Although the thing of illustration shows that the some auxiliary | assistant spiral blade was comprised by two, it may comprise not only this but three or more. For example, when a plurality of auxiliary spiral blades are configured by three, the outer diameter of the auxiliary spiral blade closest to the upper spiral blade 15 is the smallest, the outer diameter of the auxiliary spiral blade disposed at the top is large, and the middle The outer diameter of the auxiliary spiral wing located at is larger than the outer diameter of the auxiliary spiral wing closest to the upper spiral wing 15 and smaller than the outer diameter of the auxiliary spiral wing arranged at the top. Accordingly, the outer diameters of the three auxiliary spiral blades are increased at a constant ratio.
[0039]
In this way, the helical wings arranged on the outer peripheral surface of the pile body 11 are configured by adding not only the tip helical wing 14 and the upper helical wing 15 but also a plurality of auxiliary helical wings, thereby increasing the rotational driving force. And the bearing capacity of the pile can be increased. In particular, when the support layer is soft, it is effective to increase the support force by such a configuration.
[0040]
Next, still another embodiment of the foundation pile according to the present invention will be described with reference to FIGS. 9 and 10. In FIG. 9, the fragmentary sectional view of the foundation pile is shown, and the front view of the front-end | tip of a foundation pile is shown in FIG. As shown in FIGS. 9 and 10, at least one inner spiral blade 31 is welded to the inner peripheral surface of the pile body 11 at a position about 1 to 2 times the diameter of the pile body 11 from the opening. Is provided. The illustrated one is a position about 1 to 2 times the diameter of the pile main body 11 from the opening, and one inner spiral blade 31 is provided at the same position as the tip spiral blade 14 is provided. . More specifically, an inner spiral blade 31 is provided along the inner surface of the tip spiral blade 14.
[0041]
Thus, by providing the inner spiral blade 31 on the inner peripheral surface of the pile main body 11, the bending stress of the pile main body 11 received by the spiral blade provided on the outer peripheral surface of the pile main body 11 is reduced and the supporting force is increased. Can be made.
[0042]
Next, still another embodiment of the foundation pile according to the present invention will be described with reference to FIG. As shown in FIG. 11, a connecting pile 32 having an outer diameter larger than the outer diameter of the pile body 11 of the foundation pile 10d is welded or jointed to the foundation pile 10d at the base end (upper side in FIG. 11). Connected, the overall length of the pile is longer. The connection pile 32 shown in FIG. 11 is connected to the foundation pile 10 d by a flange joint 33.
[0043]
By comprising in this way, sufficient supporting force can be obtained resisting the horizontal force concerning the upper part of a pile.
[0044]
【The invention's effect】
As described above, according to the foundation pile of the present invention, the foundation pile is buried by projecting the tip of the pile body by a predetermined length from the tip spiral wing that is the spiral wing located closest to the tip of the pile body. The earth and sand pressed on the bottom surface of the tip spiral wing by the rotation of the tip spiral wing at this time is held between the bottom surface of the tip spiral wing and the outer peripheral surface on the tip end side of the pile body, and enters the pile body from the opening. Since it is not allowed to flow in, the earth and sand are held between the spiral blade at the tip and the outer peripheral surface of the tip of the pile body during and after the pile body is buried in the ground, and the rotation propulsion to the ground is promoted and the construction time Can be shortened, and the supporting force can be maintained over a long period of time. That is, in the foundation pile according to the present invention, the spiral wings bite into the earth and sand by the rotation of the pile body, and the rotation is propelled by using the strength of the ground as a reaction force. At this time, since the tip of the pile body protrudes from the tip spiral wing by a predetermined length, the soil below the tip spiral wing does not enter the pile body from the opening and prevents internal blockage in the pile body. be able to. In addition, because the pile body side is not compacted on the side of the pile main body like a closed pile like the conventional one, there is no frictional resistance of extra earth and sand on the side of the pile main body, and rotation propulsion is easy. It is possible to increase the efficiency of construction. Furthermore, when the tip of the pile reaches the support layer, it is possible to hold the earth and sand in a wide area between the bottom surface of the tip spiral blade and the tip outer peripheral surface of the pile body, and to spread the load widely on the ground. It is possible to maintain the pile over a long period of time with a support force larger than the support force of the closed pile as in the prior art.
[0045]
Moreover, when the length of the tip of the pile main body protruding from the tip spiral wing is set to be about 1 to 2 times the diameter of the pile main body, rotation propulsion to the ground is facilitated and the ground holding force is surely exhibited. I can do it.
[0046]
In addition, when the outer diameter of the tip spiral wing is set to 2 to 3 times the diameter of the pile body, sufficient support force can be obtained by receiving ground reaction force, while large rotational force is required to bite into the ground. Not needed.
[0047]
Further, two spiral wings are arranged on the outer peripheral surface of the pile body, one is the tip spiral wing, and the other one is 1.5 centimeters of the outer diameter of the tip spiral wing upward from the tip spiral wing. When the upper spiral wing having an outer diameter larger than the outer diameter of the tip spiral wing is arranged with a spacing of twice or twice, it is soft with a high water content until reaching a relatively hard ground. Even if there is a silt layer, the pile body can be buried and promoted in the ground without any trouble. After embedding, the leading spiral wing and the upper spiral wing can each exert their supporting force.
[0048]
In addition, if a reinforcing plate is provided at the tip protruding from the tip spiral wing of the pile body and the excavating blade is fixed to the reinforcing plate, even if the tip of the pile body enters into the hard ground serving as a support layer, There is no risk of being deformed or crushed by the pressure.
[0049]
Also, a friction cut plate is provided along the inner peripheral surface of the tip portion protruding from the tip spiral blade of the pile body, the end portion of the friction cut plate is protruded from the tip end of the pile body, and the cut end portion is cut. When the blade is formed, it is possible to improve the efficiency of laying the foundation pile.
[0050]
In addition, the spiral wing arranged on the outer peripheral surface of the pile body is composed of a tip spiral wing, an upper spiral wing, and a plurality of auxiliary spiral wings, and the plurality of auxiliary spiral wings are arranged at regular intervals in the axial direction of the foundation pile. The auxiliary spiral blade closest to the upper spiral blade is disposed at an interval of 1.5 to 2 times the outer diameter of the tip spiral blade upward from the upper spiral blade, and the outer diameter of the upper spiral blade If the outer diameter is larger than that, the rotational driving force can be increased and the supporting force of the pile can be increased. Furthermore, it can also be used as a multi-blade bearing pile (friction pile) supported by an intermediate layer in the ground where the support layer is deep.
[0051]
Moreover, it provided in the outer peripheral surface of the pile main body 11 by providing at least 1 or more inner spiral wing | blade in the inner peripheral surface of a pile main body in the position of about 1 to 2 times the diameter of a pile main body from an opening part. While reducing the bending stress of the pile main body 11 received by the spiral wing, the supporting force can be increased.
[0052]
In addition, by connecting a connecting pile having an outer diameter larger than the outer diameter of the pile body of the foundation pile to the base end of the foundation pile, a sufficient supporting force is obtained against the horizontal force applied to the upper part of the pile. Can do.
[Brief description of the drawings]
FIG. 1 is a perspective view showing an embodiment of a foundation pile according to the present invention.
FIG. 2 is a partially omitted perspective view showing a modified example of the foundation pile of FIG.
FIG. 3 is a perspective view showing another embodiment of a foundation pile according to the present invention.
4 is a partial cross-sectional view of the foundation pile shown in FIG.
FIG. 5 is a partially omitted perspective view showing a conventional steel pipe pile.
6 is a longitudinal sectional view in which a part of the steel pipe pile of FIG. 5 is omitted.
7 is a cross-sectional view taken along the line AA in FIG.
FIG. 8 is a partial perspective view showing another embodiment of the foundation pile according to the present invention.
FIG. 9 is a partial sectional view showing still another embodiment of the foundation pile of the present invention.
10 is a front view of the tip side of the foundation pile shown in FIG. 9. FIG.
FIG. 11 is a partial perspective view showing still another embodiment of the foundation pile of the present invention.
FIG. 12 is a partial perspective view showing still another embodiment of the foundation pile of the present invention.
13 is a front view of the tip side of the foundation pile shown in FIG. 12. FIG.
[Explanation of symbols]
10, 10a, 10b, 10c, 10d foundation pile
11 Pile body 11a Tip protrusion
12 Open end 12a Opening
13 Drilling 14 Tip spiral wing
14a Front end 14b Drilling blade
14c Inclined surface 15 Upper spiral wing
17 Space 18 Reinforcement plate (outer tube)
19 Friction cut plate 20 Cutting blade
30a, 30b Auxiliary spiral wing 31 Inner spiral wing
32 Connection pile 33 Flange joint

Claims (9)

In the foundation pile formed by arranging one or two or more spiral wings on the outer peripheral surface of the pile body having an opening at the tip,
A tip protrusion is formed by protruding the tip of the pile body from the tip spiral wing, which is a spiral wing located closest to the tip of the pile body, by 1 to 2 times the diameter of the pile body;
A friction cut plate is provided along the inner peripheral surface of the tip portion protruding from the tip spiral blade of the pile body, and the end portion of the friction cut plate protrudes from the tip end of the pile body, and the cut end portion is cut. Forming a blade,
Around the tip protrusion, a space for holding soil in a compacted state is defined between the bottom surface of the tip spiral wing and the outer peripheral surface on the tip side of the pile body,
A foundation characterized in that earth and sand pressed on the bottom surface of the tip spiral blade by rotation of the tip spiral blade at the time of burying the foundation pile are held in the space and do not flow into the pile body from the opening. Pile. In the foundation pile according to claim 1,
The foundation pile according to claim 1, wherein the tip spiral wing has an outer diameter that is twice to three times the diameter of the pile body. In the foundation pile according to claim 1 or 2,
There are two spiral wings arranged on the outer peripheral surface of the pile body, one is the tip spiral wing, and the other one is 1. A foundation pile characterized by being an upper spiral wing having an outer diameter larger than the outer diameter of the tip spiral wing arranged at an interval of 5 to 2 times. In the foundation pile according to claim 3,
The spiral wing disposed on the outer peripheral surface of the pile body is composed of the tip spiral wing, the upper spiral wing, and a plurality of auxiliary spiral wings, and the plurality of auxiliary spiral wings are arranged in the axial direction of the foundation pile. The auxiliary spiral wings that are arranged at regular intervals and are closest to the upper spiral wings are spaced apart from the upper spiral wing by 1.5 to 2 times the outer diameter of the tip spiral wing. A foundation pile having an outer diameter larger than an outer diameter of the upper spiral wing. In the foundation pile according to claim 4,
The outer diameter of each auxiliary spiral blade is a constant ratio so that the outer diameter of the auxiliary spiral blade closest to the upper spiral blade is the smallest and the outer diameter of the auxiliary spiral blade disposed at the top is the largest. A foundation pile characterized by being larger. In the foundation pile according to any one of claims 1 to 5,
A foundation pile characterized in that at least one inner spiral wing is provided on the inner peripheral surface of the pile body at a position about 1 to 2 times the diameter of the pile body from the opening. In the foundation pile according to claim 6,
One of the inner spiral wings is provided at the same position as the position where the tip spiral wing is provided. In the foundation pile according to any one of claims 1 to 7,
A foundation pile comprising a reinforcing plate provided along an outer peripheral surface of a tip portion protruding from the tip spiral blade of the pile body, and a drilling blade fixed to the reinforcing plate. In the foundation pile according to any one of claims 1 to 8,
A foundation pile, wherein a connection pile having an outer diameter larger than an outer diameter of a pile body of the foundation pile is connected to a base end of the foundation pile.

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