JPH11269875A - Rotation embedding open end pile - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce excavation torque and improve penetration efficiency by opening the edge of a pile body composed of a steel pipe and proving a blade to the outside face of the edge part of the pile body. SOLUTION: When a pile body 1 is pressed into underground by the pushing device of a pile driving machine while the pile body 1 is rotated by the motor of a heavy machine mounted on the head part of the pile body 1, soil and sand at the edge side of excavation are made soft by the edge part 2a of a blade 2. The excavated soil and sand are easily moved upward of the body part of the blade 2 continuing to the edge part 2a, and penetration force is reproduced while compression is performed in the above. When a soft layer exists on a hard support layer, the soil and sand pushed in the inside of the pile body at the time when the pile body 1 passes the soft layer are pushed upward by the soil and sand of the support layer pushed in at the time when the support layer is passed. The compression soil and sand of the support layer enclosed in the pile body 1 constitute the support bottom part of the pile receiving penetration resistance from the ground together with the edge face 1b of the pile body 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary buried pile with blades used for a foundation of a building or the like.

[0002]

2. Description of the Related Art A rotary buried pile has already been proposed in order to solve the noise and vibration problems in the case of a hitting method or a press-fitting method. As disclosed in Japanese Patent Publication No. 2-62848, the conventional rotary buried pile basically has a closed-end pile in which the opening at the tip of the pile body is closed by a bottom plate, and is excavated in the bottom plate to reduce penetration resistance. A blade is provided, and a spiral blade is provided on the outer surface of the lower end of the pile body. In this rotary buried pile, the excavation blade at the tip softens the soil at the tip of the pile body, and is screwed into the unexcavated soil on the side surface so as to cut the blade.

[0003] However, since the blades are provided on the side of the pile body above the bottom plate and the excavating blades and the blades are arranged discontinuously, the earth and sand below the bottom plate hardly move upward during construction, and the propulsion force is reduced. It may not be able to demonstrate. In particular, when the ground at the bottom plate is hard and the ground near the blades is loose, considerable excavation is required for earth and sand to move above the blades. In order to enhance the excavation effect, a large blade may be provided on the bottom plate, but in this case the construction efficiency will be improved, but the ground at the tip will be loosened even at the time of hitting, and an effective bearing capacity will be obtained. Will not be able to do it.

Japanese Patent Application Laid-Open No. H8-326053 discloses a spiral bottom plate having a diameter of about twice the diameter of a pile main body, which is formed by cutting a tip portion of a tubular pile main body spirally along the outer periphery. A steel pipe pile fixed to a notch tip surface of a pile body is disclosed. In this steel pipe pile, the spiral bottom plate that also serves as a drilling blade can promote excavation softening of the earth and sand at the tip of the pile body, and it is said that even if the pile body has a large diameter, it can be easily rotated and driven into the ground. In general, there is no change in that the tip opening is a closed-end pile closed by a bottom plate. For this reason, the ground part receives a large reaction force of the ground at the time of construction. The present inventors have proposed an open-ended pile having an open tip in Japanese Patent Application No. 9-314461 for the purpose of reducing the resistance at the tip of the pile and reducing the excavation torque at the time of construction. This is an application example of the present invention, in which the excavation efficiency (reduction of excavation torque and improvement of penetration efficiency) is dramatically increased.

[0005]

That is, the present invention is directed to an open-ended rotary buried pile in which the tip of a pile body is open, and an object of the present invention is to provide an apparent pile when the ground strength suddenly increases. An object of the present invention is to provide a rotary buried open-end pile in which the above-mentioned tip resistance is reduced to facilitate the penetration propulsion and the finally obtained supporting force is large.

[0006]

Means for Solving the Problems Hereinafter, a description will be given using reference numerals in the accompanying drawings. In the rotary buried open-ended pile according to the first aspect of the present invention, a tip of a pile main body 1 made of a steel pipe or a hollow pipe of another material. And one or more blades 2 are provided on the outer side surface 1a of the tip of the pile body 1. According to the second aspect of the present invention, in the rotary buried pile according to the first aspect of the present invention, the distal end portion 2a of the blade 2 (the lowermost blade when there are a plurality of blades) is projected downward from the distal end surface 1b of the pile main body 1. According to the third aspect of the present invention, in the rotary buried open-ended pile according to the second aspect of the present invention, the tip 2a of the blade 2 is extended in the radial direction so as to protrude from the inner side surface 1c of the pile main body 1. According to the fourth aspect of the present invention, in the rotary buried open-end pile according to the first aspect of the present invention, the blades 2 are made of a wear-resistant steel plate or a low-friction steel plate. According to the fifth aspect of the present invention, in the rotary buried open-end pile according to the first aspect of the present invention, the excavation bit 3 is attached to the tip 2a of the blade 2 (the lowermost blade when there are a plurality of blades). According to the sixth aspect of the present invention, in the rotary buried open-ended pile according to the first aspect of the present invention, the width of the blade 2 is narrowest at the tip 2a,
It is changed in the circumferential direction so that the upper part 2b becomes the widest. According to the seventh aspect of the present invention, in the rotary buried open-end pile according to the first aspect of the present invention, the thickness of the blades 2 is adjusted to the outer surface 1 of the pile body 1.
The inner peripheral side portion 2c joined to a is changed in the radial direction so that the inner peripheral side portion 2c is the thickest and the outer peripheral side portion 2d is the thinnest. According to the invention of claim 8, in the rotary buried open-end pile according to the invention of claim 1, an end portion of the pile main body 1 below the blade 2 (the lowermost blade when there are a plurality of blades) is cut along the blade 2. I do. According to the ninth aspect of the present invention, the tip of the pile body 1 made of a steel pipe or a hollow pipe made of another material is opened, and one or more sheets are provided on the outer surface 1a of the tip of the pile body 1 or the tip surface 1b of the pile body 1. And the inner peripheral side portion 2c of the blade 2 provided on the tip end surface 1b is projected from the inner side surface 1c of the pile main body 1.

In this rotary buried open-end pile, when the pile body 1 is pressed into the ground by a pushing device of a pile driver while the pile body 1 is rotated by a motor of a heavy machine placed on the head of the pile body 1, the blades 2 The earth and sand on the excavation tip side is softened by the tip 2a. This excavated earth and sand easily moves above the main body portion of the blade 2 continuous with the tip portion 2a, and regenerates the penetrating force while being compressed upward. If a soft layer is present on the non-soft support layer, the soft soil sediment pushed into the inside of the pile body 1 when the pile body 1 passes through the soft layer will be pushed in when the pile body 1 passes through the support layer. It is pushed up by the layer of earth and sand. The compressed sediment of the support layer confined in the pile main body, together with the tip end surface 1b of the pile main body 1, constitutes a support bottom of the pile that receives penetration resistance from the ground. The shape of the blade 2 is not limited to a spiral shape, and other known shapes such as a flat plate shape can be used.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the embodiment shown in FIGS. 1 and 2, an outer side surface 1a of a tip portion of a pile main body 1 made of a steel pipe has
One spiral wing 2 made of a wear-resistant steel plate is welded. The tip 2a of the blade 2 is the tip 1b of the pile body 1.
And are located at the same level. Mild Steel Hardness (Vikasu hardness) is H _v> 300 is a wear steel whereas an H _v = 120 to 150. Therefore, it is more effective to use a wear-resistant steel plate as the blade material. In the embodiment shown in FIGS. 3 and 4, one spiral wing 2 made of a low friction steel plate is welded to the outer surface 1a of the tip of the pile main body 1 made of a steel pipe. The tip 2a of the blade 2 is the blade 2
Projecting downward from the tip end face 1b of the pile body 1 by an amount corresponding to the thickness of the pile body 1. The coefficient of friction (α) between soil (sand) and mild steel usually varies from 0.3 to 0.6. The relationship between the required torque (T _r ) and the friction coefficient (α) is T _r = aα + b, where b is usually a
Since it is smaller than α, the friction coefficient has a large effect on torque. Therefore, it is more effective to use a low friction steel plate as the blade material. In the embodiment shown in FIGS. 5 and 6, the outer surface 1a of the tip of the pile main body 1 made of steel pipe is provided with:
One spiral wing 2 made of a steel plate is welded. The tip 2a of the blade 2 protrudes below the tip 1b of the pile body 1 by an amount equivalent to the thickness of the blade 2, and the inner end 2e of the tip 2a crosses the tip 1b of the pile 1 to It projects into the lower space of the hollow part of the main body 1.

In the embodiment shown in FIGS. 7 to 10, a single spiral wing 2 made of a steel plate is welded to the outer surface 1a of the tip of a pile body 1 made of a steel pipe. The tip 2a of the blade 2 protrudes below the tip 1b of the pile body 1 by an amount corresponding to the thickness of the blade 2, and a drill bit 3 is welded to the lower surface of the tip 2a. This drill bit 3
8 and 9 can be variously changed as shown in FIGS. 8 and 9, and the use of a wear-resistant steel plate is more effective.
As shown in FIG. 10, the tooth tip of the excavation bit 3 formed integrally with or separately from the blade can be hot worked and heat treated. 16 and 17 show examples of the shape of the drill bit welded to the blade tip, and FIGS. 18 and 19 show other examples of the shape of the drill bit. However, the present invention is not limited to these examples. In the embodiment shown in FIG. 11, one spiral blade 2 made of a steel plate is welded to the outer side surface 1a of the tip of the pile main body 1 made of a steel pipe. The tip 2 a of the blade 2 is arranged at the same level as the tip 1 b of the pile body 1. Feather 2
Are formed in the circumferential direction so that the tip 2a is the narrowest and the upper end 2b is the widest. In this example, the width of the tip 2a is half the width of the upper end 2b. .

In the embodiment shown in FIGS. 12 and 13, a single spiral wing 2 made of a steel plate is welded to the outer side surface 1a of the tip of the pile main body 1 made of a steel pipe. The tip 2 a of the blade 2 is arranged at the same level as the tip 1 b of the pile body 1. As clearly shown in FIG. 10, the thickness of the blade 2 is the inner peripheral portion 2 c welded to the outer surface 1 a of the pile body 1.
Is thickest, the outer peripheral side portion 2d is the thinnest, and the vertical cross section of the blade is turned sideways to form a trapezoidal shape. In the embodiment shown in FIG. 14, the outer surface 1a of the tip of the pile main body 1 made of a steel pipe is used.
, One spiral blade 2 made of a steel plate is welded. The tip 2 a of the blade 2 is arranged at the same level as the tip 1 b of the pile body 1. An end portion of the pile main body 1 below the blade 2 is spirally cut along the lower surface of the blade 2.
In the embodiment shown in FIG. 15, the end of the pile main body 1 made of a steel pipe is cut spirally, and one spiral blade 2 made of a steel plate is welded to the tip end face 1 b of the pile main body 1. I have.
The inner radius of the blade 2 is smaller than the inner radius of the pile body 1,
The inner peripheral side portion 2 c of the blade 2 protrudes from the inner side surface 1 c of the pile main body 1.

[0011]

As described above, in the rotary buried open-ended pile according to the first aspect of the present invention, the tip of the pile body is opened and one or more blades are provided on the outer surface of the tip of the pile body. When the ground strength sharply increases (when the tip resistance sharply increases compared to the propulsion force), the apparent tip resistance decreases and the penetration becomes easy. Further intrusion promotes the obstruction effect and increases the intrusion resistance, but at that time the propulsive force is also increased and penetrates sufficiently. Thereby, the construction efficiency is improved, and the supporting force at the tip of the pile is sufficiently secured. In the rotary buried open-end pile according to the second aspect of the present invention, in addition to the configuration according to the first aspect of the present invention, the tip of the blade protrudes downward from the tip end surface of the pile main body. Since the solid ground deeper than the tip end face of the main body is excavated in advance and the periphery of the pile main body is excavated, the apparent tip resistance of the bottom part is reduced, and penetration is facilitated.

[0012] In the rotary buried open-ended pile according to the third aspect of the present invention, in addition to the configuration of the second aspect, the tip of the blade is extended in the radial direction so as to protrude from the inner side surface of the pile main body. The resistance of the end edge of the main body can be reduced, and the penetration efficiency can be improved. In the rotary buried open-ended pile according to the fourth aspect of the present invention, in addition to the above-described configuration of the first aspect, a wear-resistant steel plate or a low-friction steel plate is used as the blade material, so that wear and friction at the blade portion during construction are small. Therefore, the required torque is reduced, which is economical. In the rotary buried open-end pile according to the fifth aspect of the present invention, in addition to the configuration according to the first aspect of the present invention,
Since a drill bit was attached to the tip of the blade with severe wear,
Excavation power and propulsion power do not decrease and construction efficiency can be maintained high.

According to a sixth aspect of the present invention, in addition to the configuration of the first aspect of the invention, in addition to the configuration of the first aspect of the invention, the width of the blade mainly receiving resistance is increased in the circumferential direction so as to increase from the tip toward the upper side. And the shape corresponds to the moment generated on the blade due to the ground reaction force at the tip of the pile, so that the blade can be designed economically and efficiently. In addition, the penetration resistance is reduced and the torque required for penetration and excavation is reduced. In the rotary buried open-ended pile according to the seventh aspect of the present invention, in addition to the configuration according to the first aspect of the present invention, the thickness of the blade mainly receiving resistance is reduced in the radial direction so as to decrease as the distance from the outer surface of the pile body increases. The shape is adapted to the moment generated on the blade due to the ground reaction force at the tip of the pile, so that the blade can be designed economically and efficiently. In addition, since the penetration resistance is reduced and the required torque is reduced, economy is improved and construction efficiency is improved.

In the rotary embedded open-ended pile according to the eighth aspect of the present invention, in addition to the above-described configuration of the first aspect, the end portion of the pile main body below the blade is cut along the blade, so that the pile from the ground can be removed. The part receiving the reaction force is only the tip of the blade (line contact) and can be constructed without receiving a large resistance. At the same time, the penetration becomes better and the resistance of the pile body and pipe soil is small,
Penetration becomes easy, and the excavation force at the tip increases. Further, when the soil in the pipe is closed, the soil at the lower portion of the open end easily moves to the side, and the upper portion of the blade is easily filled with the soil, so that the propulsion force does not decrease. In the rotating buried open-ended pile according to the ninth aspect of the present invention, the inner peripheral side portion of the blade provided on the tip end surface of the pile main body is made to protrude from the inner side surface of the pile main body. , Because it is not immediately closed, the penetration efficiency does not decrease. Further, since the blade is supported by the edge of the pile main body, the moment generated at the end of the pile due to the ground reaction force is small, and the blade is easily welded.

As described above, in the rotary buried open-ended pile according to the present invention, since the resistance at the tip of the pile can be reduced, the pile can be constructed with a relatively small construction machine, and the construction cost can be reduced. In addition, since the penetration efficiency is increased, the work can be performed in a short construction period. Furthermore, the penetration into the supporting ground is improved, and the supporting force is increased in order not to disturb the ground immediately below the pile.

[Brief description of the drawings]

FIG. 1 is a perspective view from below of a distal end portion of a rotary buried open-end pile according to a first embodiment of the present invention.

FIG. 2 is a bottom view of the rotary buried open-end pile of FIG. 1;

FIG. 3 is a perspective view from below of a distal end portion of a rotary buried open-end pile according to a second embodiment of the present invention.

FIG. 4 is a bottom view of the rotary buried open-ended pile shown in FIG. 3;

FIG. 5 is a perspective view from below of a tip portion of a rotary buried open-end pile according to a third embodiment of the present invention.

FIG. 6 is a bottom view of the rotary buried open-ended pile shown in FIG. 5;

FIG. 7 is a front view of a tip portion of a rotary buried open-ended pile according to a fourth embodiment of the present invention.

FIG. 8 is a front view showing another mode of the fourth embodiment.

FIG. 9 is a front view showing still another mode of the fourth embodiment.

FIG. 10 is a front view showing another aspect of the fourth embodiment.

FIG. 11 is a bottom view of a rotary buried open-end pile according to a fifth embodiment of the present invention.

FIG. 12 is a perspective view from below of a distal end portion of a rotary buried open-end pile according to a sixth embodiment of the present invention.

FIG. 13 is a vertical sectional view of a tip portion of the rotary buried open-ended pile shown in FIG. 1;

FIG. 14 is a perspective view from below of a distal end portion of a rotary buried open-end pile according to a seventh embodiment of the present invention.

FIG. 15 is a perspective view from below of a distal end portion of a rotary buried open-end pile according to an eighth embodiment of the present invention.

FIG. 16 is a front view showing an example of a shape of a drill bit welded to a blade tip in the embodiment of the present invention.

17 is a bottom view of the drill bit shown in FIG.

FIG. 18 is a front view showing another example of the shape of the drill bit welded to the blade tip in the embodiment of the present invention.

19 is a bottom view of the excavation bit shown in FIG.

[Explanation of symbols]

 1 pile body 2 blade 3 drill bit

Claims (9)

[Claims] 1. A rotary buried open-end pile in which a tip of a pile body made of a steel pipe or a hollow pipe of another material is opened, and one or more blades are provided on an outer surface of a tip portion of the pile body. 2. The rotating buried open-end pile according to claim 1, wherein the tip of the blade protrudes below the tip surface of the pile body. 3. The rotating embedded open-end pile according to claim 2, wherein the tip of the blade is extended in the radial direction so as to protrude from the inner surface of the pile main body. 4. The rotating embedded open-end pile according to claim 1, wherein a wear-resistant steel plate or a low-friction steel plate is used for the blades. 5. The rotating buried open-end pile according to claim 1, wherein a cutting bit is attached to a tip of the blade. 6. The rotary buried open-ended pile according to claim 1, wherein the width of the blade is changed along the circumferential direction so as to increase from the tip to the upper side. 7. The rotating embedded open-end pile according to claim 1, wherein the thickness of the blade is changed along the radial direction so as to decrease as the distance from the outer surface of the pile body increases. 8. The rotating buried open-end pile according to claim 1, wherein an end portion of the pile body below the blade is cut off along the blade. 9. A pile body made of a steel pipe or a hollow pipe made of another material is opened, and one or a plurality of blades are provided on an outer surface of a tip portion of the pile body or a tip surface of the pile body. A rotating buried open-end pile in which the inner peripheral side portion of the blade provided in the above is protruded from the inner surface of the pile body.