JP2002339353A - Rotatively-buried foundation pile - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rotatively-buried foundation pile which enables continuation of smooth forward excavation without being attended with deflections, vibrations, etc., even in a case of an encounter with foreign matter mixed into ground, unevenly distributed hard layers, etc., midway through work for burying the pile, and which can make working efficiency and ground reinforcing performance much higher than ever. SOLUTION: A screw bit, which is mounted on a lower-end outer peripheral surface of a steel pipe of a prescribed length, is characterized as follows: at least two split bits are mounted in a state wherein excavating blades, which are provided at lower edges of the respective split bits, are arranged in such a manner as to be spaced at approximately regular intervals in a peripheral direction of the steel pile and located to be approximately flush with one another; and a circular length of the split bit is equal to/greater than a length equivalent to half a pitch of a screw. Alternatively, an annular bit, which is used in place of the screw bit, can be mounted in such a manner that two split bits, which are split in two in a radial direction of the annular bit, are arranged as above in a state of being inclined at a prescribed angle with respect to a horizontal plane.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary embedded foundation pile for reinforcing a ground, which is similar to a type in which a screw bit is attached to an outer peripheral surface of a steel pipe.

FIG. 6 shows an example of a conventional rotary embedded foundation pile of the type described above. This conventional rotary embedded foundation pile B
A screw bit 52 is provided at a plurality of locations on the outer peripheral surface of a steel pipe pile body 51 having a predetermined length at predetermined intervals in an axial direction.
Is installed. Each screw bit 52 has a length corresponding to one pitch of the screw. And, at the lower edge of each screw bit 52, a digging blade 52
a is formed. A tip bit (guide bit) 53 is attached to the lower end of the pile main body 51.

[0003] This rotary embedded foundation pile B has
As shown in FIG. 6, a self-propelled rotary embedding machine C is supported by a rotating head 62 attached to a pile support arm 61 in a manner capable of engaging and disengaging from a rotating head 62, and utilizing its own weight in the ground. Screwed into.

[0004] Alternatively, although not shown, a plate-shaped bit obtained by dividing the disk into two in the radial direction is arranged so as to be inclined in a direction crossing each other, so as to close the open lower end of the pile body. A type of rotary embedded foundation pile is also known.

[0005]

The ground to be reinforced by burying foundation piles is not limited to soil with low excavation resistance, such as sand or clay, and is partially hardened.
There are many cases where rock masses, concrete masses and other hard foreign materials are present.

[0006] When the screw bit 52 encounters the above-mentioned partially hard place before reaching the hard stratum which is to be the buried foundation of the pile, the conventional rotary embedded foundation pile B is placed at one of the lower ends thereof. Is pushed to the softer side of the stratum, and the pile body 51 is shaken.

In this case, the buried portion of the pile body 51 is loosely pressed against the ground. In addition, the screw bit 52 itself receives a strong vibration action. Therefore, the structural strength of the screw bit 52 and the mounting strength to the pile main body 52 must be sufficiently increased in consideration of the safety factor.

[0008] Therefore, an object of the present invention is to avoid the occurrence of shake vibration and the like even when encountering a mixed foreign substance in the ground or an unevenly distributed hard stratum while the embedding work is proceeding to a predetermined depth. It is constructed so that it can continue to excavate smoothly. Compared with the conventional one, it greatly improves the work efficiency and the ground reinforcement function, and also withstands the strong excavation resistance without increasing the production cost. It is an object of the present invention to provide a rotary embedded foundation pile improved to obtain.

[0009]

In order to achieve the above object, a rotary embedded foundation pile according to the present invention has a screw bit attached to an outer peripheral surface of a lower end portion of a steel pipe having a predetermined length. Screw bits, two or more divided bits having an arc length of half the pitch of the screw or more, the excavation blade provided at each lower edge, at substantially equal intervals in the circumferential direction of the steel pipe, and It is characterized in that it is mounted so as to be located on substantially the same horizontal plane. Then, the tip bit may be attached so as to close the open lower end of the steel pipe. Or, at several places around the open lower end of the steel pipe,
A chip bit may be attached. Alternatively, an annular bit is attached to an outer peripheral surface of a lower end portion of a steel pipe having a predetermined length, and the annular bit is formed by dividing an annular plate having an inner diameter that can be fitted onto the steel pipe into two in the radial direction. The excavating blades provided at the lower edge of each of the divided bits occupy a substantially symmetrical position on the diameter line of the steel pipe, and are arranged substantially on the same horizontal plane, and are inclined at a predetermined angle with respect to the horizontal plane. It is good to install in the state where it was set.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to FIG. FIG. 1 shows a rotary embedded foundation pile (hereinafter simply referred to as a foundation pile) A1 of this embodiment.
The top and bottom views of the foundation pile A1 are attached to the upper and lower sides thereof.

The foundation pile A1 is a steel pipe having a predetermined outer diameter and length and a predetermined thickness as a pile main body 1. A screw bit 2 is attached to the outer peripheral surface on the tip side (lower side in the figure) of the pile main body 1.

The screw bit 2 is formed by combining two divided bits 2A and 2B of a screw wound on the outer peripheral surface of the pile body 1 and having an arc length of a half pitch.

The two divided bits 2A and 2B are formed by excavating blades a and b formed at the lower end edges thereof, as shown in FIG.
The pile body 1 occupies a symmetrical position on the diameter line (V-V), and the two excavating blades a and b are welded to the pile body 1 in such an arrangement that they are located on substantially the same horizontal plane (WW). I have.

A tip bit 3 is attached to the open lower end of the pile body 1 so as to close the opening. The tip bit 3 of this embodiment comprises a circular base plate 3a fitted to the open lower end and welded to the pile body 1, and a plate-like blade 3b with a sharp tip attached to the lower surface thereof. Have been.

Further, on the inner peripheral surface on the upper end side of the pile main body 1, rotation projections 4 are attached at two positions on the diameter line. As shown in FIG. 6, the set of rotation projections 4 and 4 is removably connected to a rotation head 62 mounted on a pile support arm 61 of a self-propelled rotary burying machine C. It is to make it.

Next, the operation of the foundation pile A1 will be described. Foundation pile A attached to rotating burial machine C as described above
1 starts the rotating head 62 with the tip bit 3 pressed against a predetermined position on the ground by its own weight.
First, the tip of the tip bit 3 bites into the ground.

Accordingly, the excavating blades a and b of the set of divided bits 2A and 2B are screwed into the ground as the pile body 1 rotates. Then, the pile main body 1 drawn into the ground along with the screw bit 2 compresses the stratum around the periphery thereof, whereby the primary reinforcement effect of the ground by the foundation pile A1 is generated. When the tip of the foundation pile A1 reaches the hard ground, its original reinforcing effect is obtained.

By the way, it is not rare that the tip of the foundation pile A1 encounters a hard stratum unevenly distributed in the ground or a hard foreign substance such as a rock mass before reaching the predetermined depth.

In this case, in the case of the conventional rotary embedded foundation pile B described at the beginning, since the excavating blade 52a of each screw bit 52 is provided only at one location, a hard location is avoided. Behave like. For this reason, the whole of the rotary-embedded foundation pile B causes a sliding motion, so that the press-fitting state between the embedding portion and the stratum is loosened. In addition, the screw bit 52 is also damaged by the eccentric rotation.

On the other hand, in the case of the foundation pile A1 according to the present invention, as shown in FIG. 1, a set of divided bits 2A and 2A having an arc length corresponding to a half rotation of the pile body 1 is provided.
B, the excavating blades a and b provided at the lower end edges thereof are symmetrical on the diameter line V-V of the pile main body 1 and on the same horizontal plane W-.
It is arranged so as to be located on W.

Therefore, the excavation resistance applied to the respective excavation blades a and b during excavation of the foundation pile A1 is reduced by half as compared with the conventional case where the cutting edge is provided only at one place. Accordingly, the excavating action force of the screw bit 2 can be doubled. Also, the acting force for causing the foundation pile A1 to vibrate around its axis is significantly reduced.

FIG. 2 is a partial side view and a bottom view showing a foundation pile A2 according to a second embodiment of the present invention. The difference from the foundation pile A1 of the first embodiment is that the tip bit 3 is omitted, and instead, the tip-shaped bit 5 is provided at a plurality of positions on the periphery of the open lower end of the pile body 1, in this case at four positions.
Are projected downward at equal distances from each other.

In this manner, as the diameter of the pile body 1 increases, the degree of increase in the excavation resistance of the foundation pile A2 can be significantly reduced. Also, if the ground is hard,
Excavation efficiency can be improved.

Next, FIG. 3 is a view corresponding to FIG. 2, showing a foundation pile A3 of a third embodiment according to the present invention. The difference from the foundation pile A1 of the first embodiment is that the screw bits 2 are stacked in two upper and lower stages. The upper end of the lower divided bit 2A or 2B is the upper divided bit 2B.
Or it is integrated with 2A.

With this configuration, the lengths of the divided bits 2A and 2B of the first embodiment are each doubled. That is, the length at which the screw bit 2 is welded to the pile body 1 is doubled.

During excavation of the foundation pile A, a strong force acts on the screw bit 2. Therefore, unless the above-mentioned welding is performed not only with certainty but also with certainty, the divided bits 2A, 2
There is a possibility that B will easily come off.

Therefore, as a countermeasure, as the length of the welding line is increased, the risk of the above-mentioned peeling is reduced. Therefore, even an unskilled welding technician can easily and reliably secure the required welding strength. Further, since the force applied to the screw bit 2 is dispersed over a wide area, even if the thickness of the screw bit 2 is smaller, the screw bit 2 can endure.

Incidentally, if necessary, in order to further enhance the above-mentioned effect, a configuration in which the screw bits 2 are integrally connected in an arbitrary number of three or more stages can be adopted.

FIG. 4 is a bottom view of a foundation pile A4 according to a fourth embodiment of the present invention. The difference between the foundation pile A4 and the foundation pile A1 of the first embodiment is that
Is divided into three divided bits 2A, 2B and 2C.

Drilling blades a to c are provided at the lower edge of each of the divided bits 2A to 2C. The arc length of each of the three divided bits 2A to 2C is set to be longer than 1/3 of the circumference so that the welding joint line can be made as long as possible. Overlap each other as shown.

In this way, the excavation resistance exerted on each of the excavating blades a to c becomes approximately 1/3 as compared with the case where only one cutting edge is provided, and the excavating ability is approximately 3 times. Can be doubled. In addition, the aforementioned vibration
It is even less likely to occur.

Next, FIG. 5 is a view corresponding to FIG. 2, showing a foundation pile A5 of a fifth embodiment according to the present invention. In the foundation pile A5 of this embodiment, an annular bit 6 is attached to the outer peripheral surface of the lower end portion of the pile body 1 instead of the screw bit 2.

The annular bit 6 is composed of two divided bits 6A and 6B having a form in which an annular plate having an inner diameter capable of being fitted to the pile main body 1 is divided into two in the radial direction. Each of the divided bits 6A and 6B is inclined at a predetermined angle with respect to the horizontal plane, and the excavation blades d and e provided at the lower end edges thereof are:
The pile body 1 occupies a symmetrical position on the diameter line, and is welded to the outer peripheral surface of the pile body 1 so as to be arranged on the same horizontal plane.

The operation and effect of the foundation pile A5 are similar to those of the foundation pile A1 of the first embodiment.

[0035]

As is apparent from the above description, the rotary embedded foundation pile according to the present invention has the following practical advantages compared with the conventional rotary embedded foundation pile described at the beginning. It has the effect. (A) The screw bit for one pitch is divided into a plurality of bits in the direction of the circular arc and the arrangement state of the bits is specified, so that the excavation resistance applied to each divided bit is significantly reduced. (B) Therefore, even if the welding strength to the pile main body is not so increased, the screw bit may fall off during the excavation work. (C) Accordingly, even if the structural strength and mounting strength of the screw bit are lower, it is sufficient, and the production cost can be significantly reduced. (D) The effect of (c) is further enhanced by increasing the length of each divided bit in the arc direction. (E) During excavation, even if the screw bit collides with a hard geological layer, a rock mass, or the like, which is unevenly distributed, the pile main body is less likely to cause a slimming (eccentric) motion. (F) For this reason, the pile can be firmly and securely adhered to the ground. (G) The efficiency of the embedding work can be remarkably enhanced by smoothly moving the pile. (H) The power cost required to rotate the foundation pile can be significantly reduced.

[Brief description of the drawings]

FIG. 1 is a side view, a top view and a bottom view of a rotary embedded foundation pile according to a first embodiment of the present invention.

FIG. 2 shows the second embodiment, and is a partial side view and a bottom view thereof.

FIG. 3 is a diagram corresponding to FIG. 2, showing a third embodiment of the present invention;

FIG. 4 is a bottom view of the foundation pile according to the fourth embodiment.

FIG. 5 is a diagram corresponding to FIG. 2, showing the fifth embodiment.

FIG. 6 shows a conventional example, and is a sketch of a state in which a rotary embedded foundation pile is suspended from a rotary head of a self-propelled rotary embedded machine.

[Explanation of symbols]

 A1 to A5 Foundation pile (rotary embedded foundation pile) 1 Pile body (steel pipe) 2 Screw bit 2A, 2B Split bit 3 Tip bit 3a Base plate 3b Plate blade 4 Rotation protrusion 5 Tip bit 6 Ring bit 6A, 6B Split bits a to d Drilling blade B Conventional rotary embedded foundation pile C Self-propelled rotary embedded machine 51 Pile body 52 Screw bit 52a Cutting blade 53 Guide bit 61 Pile support arm 62 Rotary head

Claims (4)

[Claims] 1. A screw bit is attached to an outer peripheral surface of a lower end portion of a steel pipe having a predetermined length. The screw bit is formed by dividing two or more divided bits having an arc length equal to or more than a half pitch of the screw, A rotary embedding, characterized in that the excavating blades provided at the respective lower edges are mounted so as to be arranged at substantially equal intervals in the circumferential direction of the steel pipe and to be positioned on substantially the same horizontal plane. Formula foundation pile. 2. The rotary embedded foundation pile according to claim 1, wherein a tip bit is attached so as to close an open lower end of the steel pipe. 3. The rotary embedded foundation pile according to claim 1, wherein chip-shaped bits are attached at a plurality of locations on the periphery of the open lower end of the steel pipe. 4. An annular bit is attached to an outer peripheral surface of a lower end portion of a steel pipe having a predetermined length, and the annular bit is formed by dividing an annular plate having an inner diameter that can be fitted onto the steel pipe into two in the radial direction. The excavating blade provided at each lower end edge of the two divided bits occupies a substantially symmetrical position on the diameter line of the steel pipe, and is inclined at a predetermined angle with respect to the horizontal plane so as to be disposed substantially on the same horizontal plane. A rotating embedded foundation pile, which is mounted in an upright state.