JP2002105954A - Rotary penetration steel pipe pile - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a large diametral pile installable by reducing the penetration resistance and to provide a penetration steel pipe pile capable of sufficiently bringing out a support force as a pile. SOLUTION: In a rotary penetration steel pipe pile 1 provided with a blade provided with a steel pipe 2 from which the front end is cut off spirally and a spiral fixed in a shape corresponding to the front end, the blade 3 passes through the center from a point on the outer periphery of a circular steel plate and has a cut which reaches the contact position of the blade and the inner periphery of the steel pipe and further, the angle made by the outer peripheral part and the shaft of the steel pile 2 is formed in almost right angle and the front end opening of the steel pipe 2 is substantially closed and fixed as features.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary penetrating steel pipe pile in which a spiral blade is attached to the tip of a steel pipe.

[0002]

2. Description of the Related Art There have been proposed many methods of applying a rotating force to a steel pipe pile provided with a spiral blade at the tip of a steel pipe to penetrate into the ground, and some of the methods have already been put into practical use. I have. When these construction methods are classified according to the shape of the tip of the steel pipe pile, there are two types, an open-end pile with an open tip and a closed-end pile with a closed tip. From the viewpoint of the position where the blades are attached to the tip of the pile, the blades are fixed to the outer periphery of the steel pipe, and the steel pipe is cut off spirally at the tip, and the spiral blades are fixed to the surface. There are two types. Further, a large number of combinations of these have been proposed or used.
This is roughly described in FIG. 21 according to the types (described later).

Needless to say, the pile must penetrate into a solid support layer made of underground gravel, sand, clayey soil, etc., so as to surely exert the support force. Depending on the application, the pile diameter is 10
Various types of rotary penetrating steel pipe piles are required, from small diameter piles of about 0 mm to large diameter piles with pile diameters exceeding 1000 mm. In this case, compared to small diameter piles, there are various problems in terms of cost, construction method, support function, manufacturing, etc. in order to construct a large diameter pile and a rotating penetrating steel pipe pile that requires a high bearing capacity. Exists. FIG. 21 is a schematic diagram showing the performance characteristics of conventional rotary penetrating steel pipe piles of various types. Hereinafter, the problems of each type will be clarified with reference to the drawings.

(1-1) Conventional type 1 The conventional type 1 steel pipe pile shown in FIG. 21 is a closed-end pile as shown in the schematic view, and the blades are fixed not to the tip of the pile main body steel pipe but to the outer periphery of the steel pipe. I have. As an example of the conventional type 1, there is one disclosed in JP-A-59-85028 (hereinafter, referred to as an embodiment of the conventional type 1). As shown in FIG. 22, the steel pipe pile 22 in which a spiral blade 23 is fixed to the outer peripheral surface of the tip of the pile is a closed-end pile, and a bottom plate provided with an excavation blade 24 below the steel pipe pile main body 22. 29, and a structure in which a spiral wing 23 of about one turn having an outer diameter of about twice is provided on the outer periphery of the lower end portion of the steel pipe. Some excavation blades that do not require this have been proposed.

(Problems of Conventional Type 1) In Conventional Type 1, since the blades are fixed to the outer periphery of the closed-end steel pipe, the ground at the tip of the steel pipe shaft cannot be excavated. Therefore, the penetration resistance at the tip of the steel pipe is very large, the penetration does not progress during construction, and a slip phenomenon often occurs, resulting in poor workability. The slip phenomenon means that the pile hardly penetrates in the depth direction, but penetrates little by little while spinning around at the same position.
Or it is in a state where it cannot penetrate at all. When the slip phenomenon occurs, the surrounding earth and sand is disturbed by the blades, which also affects the bearing capacity. While causing a sliding phenomenon,
If it penetrates to a deeper position, the friction of the disturbed part is reduced. If the support layer is penetrated while causing a sliding phenomenon, the soil on the lower surface of the blade is disturbed, or a gap is formed on the lower surface of the blade, and the vertical support force at the tip is reduced. In order to reduce the penetration resistance, a vertical excavation blade 24 may be provided at the tip bottom plate portion 29 of the steel pipe pile 22. However, the excavation of the tip sand has an effect of reducing the penetration resistance, but the excavation blade 24 is provided at the tip of the pile. Because it disturbs the earth and sand, even the closed-end pile has a bad effect that the bearing capacity is impaired.

(Penetration, Rotational Torque, and Construction Machine) The depth of penetration of the pile per rotation (hereinafter referred to as one rotation penetration) is the height of the step portion of the blade (hereinafter referred to as blade pitch). When the construction is performed so as to substantially match with the above, the soil around the blades is not disturbed so much that the adverse effect on the bearing capacity is small, and this is considered to be the most desirable construction state. However, if the penetration of the conventional type 1 is performed so that the amount of penetration per revolution substantially matches the blade pitch (hereinafter referred to as ideal penetration), the torque required for the construction is roughly estimated to be 1.5 times of the present invention. About twice as much. The increased torque required for construction means that the required construction machinery also becomes large, which not only increases construction costs, but also results in insufficient capacity with existing construction machinery when the pile diameter is large. As a result, construction with ideal penetration becomes impossible. As is the case with the slip phenomenon, if the amount of one-turn penetration is considerably smaller than the blade pitch, the torque at the time of construction is reduced, but such a construction adversely affects the supporting force as described above.

(1-2) Conventional type 2 Conventional type 2 is an open end of conventional type 1.
An example of the conventional type 2 is disclosed in Japanese Unexamined Patent Application Publication No. 2-194212.
(Hereinafter referred to as a conventional type 2 embodiment).

(Problem of Conventional Type 2) Although the penetration resistance is smaller than that of the closed-end pile due to the use of the open-end pile, the blade is fixed to the outer periphery of the steel pipe, and the steel-pipe portion protrudes below the blade. . Therefore, when the pile is penetrated, the protruding steel pipe portion becomes a penetrating resistance. Although the penetrating property is improved as compared with the conventional type 1, the penetrating resistance is still considerably large. The torque required for ideal penetration construction of this type is approximately 1.3 times that of the present invention, and although the workability is better than that of the conventional type 1, construction of large diameter piles is still difficult. It is. Further, since the front end is an open end, it becomes difficult to secure a supporting force. To improve this point, proposals have been made to make it easier for the open end to be closed with earth and sand.However, in order to secure the supporting force, the tip must be closed with earth and sand during construction. Must be satisfied, and another means for that is required.

(1-3) Conventional type 3 In conventional type 3, the tip of a steel pipe is spirally cut out, and a helical blade corresponding to the cutout surface is fixed to the tip of the steel pipe. The tip of the steel pipe is almost closed by these blades and is classified as a closed-end pile. In this type, since the steel pipe does not protrude from the lower surface of the blade unlike the conventional type 1, the penetration resistance during construction is reduced. Regarding the shape of the tip of the shaft portion, since only a small hole is provided near the center of the spiral blade in some cases, it can be regarded as a substantially closed end. Regarding the step shape at the tip of the shaft portion, there is a small V-shaped opening inside the steel pipe when viewed from the side, but the opening area is small and the amount of earth and sand entering is small. In particular, the V-shaped root portion hardly contributes to the ingress of earth and sand. As an example of the conventional type 3, there is a steel pipe pile described in "JP-A-8-326053" (hereinafter, referred to as an example-1 of the conventional type 3). As shown in FIGS. 23 to 27, the tip of the tubular pile main body 22 is spirally notched over substantially one round along the outer periphery of the tip, and the distal end surface of the spirally cut pile main body 22. Then, a spiral cut-out plate 23 serving also as a cutting blade is formed by cutting a radial cut 26 arriving at the center in an annular disk having a diameter about twice as large as the pile main body 22 and working along the tip end surface. Welded.

(Problem of Conventional Type 3) In this type, although the penetration resistance can be reduced as compared with the conventional type 1 as described above, since the tip shape is almost a closed end, the conventional type 2 has an open end shape. In comparison, the penetration resistance is not significantly reduced. If earth and sand enter the pipe at the time of construction from the hole near the center of the blade and the stepped portion of the spiral blade, the penetration resistance is reduced by that amount, but according to the description of the above method, the hole diameter of the spiral blade is small, and The step of the blade is V-shaped because the inside is smaller than the outside, and the opening area of the step is considerably small. Therefore, the intrusion of the earth and sand into the pipe is slight, and hardly contributes to the reduction of the penetration resistance. That is,
The conventional type 3 has a substantially closed end shape and therefore has high reliability of the supporting force, but the penetration resistance is almost the same as that of the conventional type 2, and it becomes difficult to perform the construction when a large diameter pile is used. Also in the case of this type, the torque required for performing the ideal penetration is approximately 1.3 times as large as that of the present invention.

Further, as shown in FIGS. 26 and 27, in the steel pipe pile 22 according to claim 2 of this publication, a digging blade 28 having a stepped blade is fixed to a spiral bottom plate 23. The excavation blade 28 disturbs the earth and sand below the tip of the steel pipe pile 22 during construction, so that the workability is improved. However, since the tip ground contributing to the tip support force of the steel pipe pile 22 is disturbed, the support force is reduced. The problem arises. According to claim 3 of this publication,
The steel pipe pile 22 is provided with a sediment entrance hole 25 for guiding excavated and softened earth and sand into the pile main body 22 in the center of the spiral bottom plate 23. Therefore, there is a possibility that the supporting force is reduced. Further, as shown in FIGS. 23 to 24, if the diameter of the earth and sand entry hole 25 is reduced, there is almost no effect on the supporting force, but it is judged that the improvement of workability cannot be expected so much.

According to the specification, "spiral bottom plate 23
Is fixed to the tip of the pile main body 22, so that the bending moment of the spiral bottom plate 23 does not act on the pile main body 22. " When a spiral bottom plate with a diameter of about twice as large as the pile body is fixed, it is impossible for the pile body to generate bending moment itself, depending on the condition of the ground under construction. In order to make it as small as possible, at least the size of the sediment entrance hole 25 must be considerably small. The purpose of making the soil enter the pile main body 22 is to reduce the tip resistance when the steel pipe pile 22 penetrates, and to improve the workability. FIG. 25 shows the start end ac and the end a ′ of the spiral bottom plate 23.
Since the closing plate 27 that closes the gap of c ′ is provided,
The effect of the earth and sand entering the pile main body 22 is further reduced, and it is determined that the effect of improving the workability is not so large. Even if there is no closing plate 27, since the cut surface at the start end ac and the end a'c 'of the bottom plate 23 is V-shaped, the side near the center of the steel pipe pile 22 is actually Penetration is not promoted, and the effective area for sediment entry is only about half of the opening area.

(Other Example of Conventional Type 3) JP-A-9-32
Japanese Patent No. 4420 discloses the one shown in FIGS. 28 to 33 (hereinafter referred to as a conventional type 3 embodiment-2). 28 to 33 are explanatory views of a screw-in type steel pipe pile. The screw-in type steel pipe pile 32 of claim 1 of the above publication is a closed end pile, and a substantially circular steel plate having a diameter larger than the diameter of the steel pipe 32 is moved from the circumference to the center of the circle as shown in FIGS. A spiral plate 33 is formed by forming a notch 34 toward the lower end of the steel pipe 32 and bending it into a shape corresponding to the lower surface shape of the distal end of the steel pipe. The spiral plate 33 is attached to the distal end of the spirally cut steel pipe 32.

As shown in FIG. 33, in the screw-in type steel pipe pile 33 of the above publication, a portion surrounded by the steel pipe in the opening 36 formed by the staggered ends of the spiral blade 32 is closed. It is closed by the member 35. Therefore, earth and sand do not enter the inside of the steel pipe 32, and there is a difficulty in improving workability. Also, even in the case where there is no closing member 35, for the same reason as in Example-1 of the above-mentioned conventional type 3, the effective opening ratio with respect to the intrusion of earth and sand is about 1/2, and the improvement in workability is not so large. . This is clear from the description that the specification clearly states that "the opening of the staggered portion formed by bending the helical plate has a small opening, so that almost no sediment enters the steel pipe". In addition, in the specification of the gazette,

In the column, "In a widely used steel pipe pile having an outer diameter of 500 to 600 mm,
It will be a big problem in the design. "

In the column, there is a description that "the present invention can also be carried out on a screw-in type steel pipe pile formed of a steel pipe having a large diameter (for example, 600 mm)." In other words, in the present invention, a large-diameter pile is intended to have a pile diameter of at most about 600 mm (this is referred to as a medium diameter in the present invention).
It is clear that large diameter piles exceeding 00 mm are not targeted.

Further, there has been proposed a conventional type 3 in which the hole at the center of the spiral blade is formed relatively large, but this belongs to the open-end pile. In this type, since the hole diameter at the center of the spiral blade is relatively large, earth and sand can enter the pipe during construction, thereby reducing penetration resistance.
Therefore, the workability is considered to be the best among the prior arts. However, since this type has a relatively large opening, it is necessary to provide a means for closing the front end opening with earth and sand during construction to secure a supporting force.

[0016]

The alluvial plain where the major cities in Japan are developing is soft ground, and it is necessary to support the superstructure by penetrating steel pipe piles to the strong support layer. Rotary penetrating steel pipe piles are a pile construction method that exhibits greater bearing capacity than conventional pile construction methods and is also superior in seismic resistance because it is a steel pipe pile. Has the performance of being able to confirm the tip support force. However, as is apparent from the above-mentioned conventional example, there are some unsolved problems also in the rotary penetrating steel pipe pile. The problems are organized below and issues to be solved are clarified.

(2-1) Relationship between Penetration Properties and Closed-end Pile / Open-end Pile When constructing a pile, the pile tip generally reaches the support layer. The support layer is a solid ground having sufficient strength to support the weight of the upper structure, and is often a layer having an N value (evaluated ground strength in a standard penetration test) of 50 or more. The ground from the ground surface to the support layer is soft ground (hereinafter, referred to as a soft layer). Even though it is a soft layer,
There is a variation in the N value from about 0 to about 50 (Even if the N value is 50, the support layer may not be formed if the layer thickness is small. Although it cannot be a layer, a somewhat hard layer is called an intermediate layer), and various layers are mixed. If the soft layers of the ground on which the piles are constructed are all layers having a small N value, construction is relatively easy even with closed-end piles such as conventional types 1 and 3. However, for example, when a layer having an N value of 30 forms an intermediate layer of several meters and it is necessary to penetrate through the layer and construct the pile, it is very difficult to construct the pile with the closed end pile. Even if construction is possible, the pile diameter is about 600 mm or less, and the pile diameter is 1000 mm.
It is almost impossible to construct large-diameter closed-end piles exceeding the limit. On the other hand, in the case of the open-end pile, if the steel pipe protrudes to the lower surface of the blade as in the conventional type 2, it has the same problem as the closed-end pile. When the tip of the steel pipe is the open end, the spiral blade is fixed to the tip of the steel pipe, and the penetration resistance is reduced by injecting earth and sand into the pipe, the workability is improved, and even in the case of a large diameter pile, the intermediate layer as described above is used. Can be penetrated. However, it is necessary that the open-end pile closes the open end when penetrating into the support layer, and satisfies the condition that sufficient supporting force is generated.

(2-2) Relationship between Supporting Force and Closed-End Pile / Open-End Pile The central issue in the pile construction method is, of course, securing the supporting force of the pile. From the viewpoint of the tip shape, the closed-end pile is most advantageous for the bearing capacity and has high reliability. In order to sufficiently support the open-ended pile, it is necessary to close the opening at the tip of the pile with earth and sand. It is generally pointed out that it is necessary to make the tip of the pile penetrate into the support layer about five times the diameter of the pile in order to close the tip of the pile and exhibit sufficient supporting force. I have. The closed-end pile is the most advantageous shape for the supporting force. However, in order to ensure that the supporting force is exerted, generally, the tip of the pile is attached to the supporting layer by 1D.
(D: pile diameter) has been performed. As described above, the closed-end pile has a problem in workability, it is very difficult to penetrate the supporting force, and it takes time and effort. Also, in the case of a large-diameter pile, an ultra-large construction machine is required, and construction itself becomes impossible due to the conditions and cost of the construction site. Therefore, many inventions have been provided in which a downward excavating blade is attached to a closed bottom plate.However, although the workability is improved, all of the inventions disturb the support layer below the pile tip and are important for securing the supporting force. It has the disadvantage of weakening the support of the part.
From these facts, all of the closed-end rotary penetrating piles that have been put to practical use have a medium diameter of about φ600 mm or less. Regarding open-ended piles, although the workability is improved, it is an issue how to ensure that the supporting force is exerted. Although the workability is superior to that of the closed-end pile, considerable effort and time are required to penetrate the support layer by about 5D, which causes a cost problem. So various improvements are needed.

(2-3) Large-diameter rotary penetrating pile and construction machine A rotary penetrating pile is a pile in which a spiral blade is fixed to the tip of a pile. Existing construction machines used for construction are roughly classified into the following two.
Be kind. The construction machine 60 shown in FIG. 38 applies a rotational force from the pile head to the pile body, and the construction machine 70 shown in FIG. 39 grips the pile steel pipe body and applies the rotational force to the pile body. Things. The construction machine 60 generally exerts a relatively small torque of about 30 tm or less, and is mainly used for construction of a pile having a middle diameter (about 600 mm) or less. The construction machine 70 generally has a torque that can be exhibited at 40.
Since there is a machine as large as about 0 tm, it can cope with the construction of large diameter piles. Particularly when the intermediate layer is penetrated by a large diameter pile or when the intermediate layer is buried in the support layer, the required torque is extremely large, and the construction machine 70 is required. This construction machine 70
Is an existing construction machine that has been conventionally used for drilling holes for cast-in-place concrete piles, rock excavation, and the like, and it is also used for construction of rotary penetration piles. Since the construction machine 60 has a structure for applying a rotating force to the pile head, the pile and the construction machine can be easily joined. However, since the construction machine 70 has a structure of gripping the body of the pile from the periphery,
Rotation penetrating pile with blades at the tip
A special jig is required to set the value to 0 (hereinafter, referred to as tubing device 70). The present inventors have already developed this special jig (hereinafter referred to as a grooved chuck collar). As shown in FIG. 10, the grooved chuck collar is a grooved collar formed with a concave groove corresponding to the spiral pitch of the blade.
No. -054133, which has been put to practical use. By using the grooved chuck collar, a rotary penetrating steel pipe pile having a blade at the tip can be inserted from above the tubing device 70. On the other hand, when the grooved chuck collar is not used, since the blades cannot pass through the tubing device, the pile is first erected on the ground, and the tubing device 70 is covered from above the pile, and workability is reduced. It will be very bad. This point will be described in detail in an embodiment described later.

(2-4) Relationship between the angle between the pile shaft and the blade Here, the angle between the pile shaft and the blade will be described with reference to the drawings. As shown in FIG. This also means the angle between a straight line drawn along the blade surface from one point on the outer periphery of the blade that protrudes outward and along the blade surface, and the pile steel pipe shaft. In order to use the above-mentioned grooved chuck collar, it is necessary that the angle is substantially a right angle, and if the perpendicularity is not ensured, even if the grooved chuck collar is used, the rotary penetrating steel pipe pile is inserted from above. In the case where the above-mentioned grooved chuck collar is not used, the workability becomes very poor as well. Therefore, when the angle between the blade and the steel pipe is considered in the prior art, the following is obtained.
In the prior art, there is no specific reference to the mounting angle between the blade and the steel pipe, and thus the judgment is made based on the description in the drawings and the specification.
It is clear from the drawing that the mounting type of the conventional type 1 is not a right angle. In the figure of the embodiment of the conventional type 2, the mounting angle is substantially a right angle. That is, in the type in which the blades are fixed to the outer periphery of the steel pipe, it can be determined that the one in which the mounting angle is a right angle is included in the related art.
On the other hand, for the conventional type 3 in which the spiral blade is fixed to the tip of the steel pipe, the mounting angle is determined to be not a right angle according to the above-described embodiment. This will be described later.

(2-5) Mechanism of Penetration of Rotating Penetrating Steel Pipe Pile with Spiral Blade Here, the mechanism of penetration of the rotating penetrating steel pipe pile by the spiral blade will be briefly described by the present inventors so far. Describe in. As shown in FIG. 34, the rotary penetrating steel pipe pile excavates earth and sand at the tip of a spiral blade (spiral bottom plate) by rotating the pile body from the ground, and excavates the earth and sand excavated on the upper surface of the blade with the rotation of the blade. It is pushed up and penetrates into the ground by the propulsion generated by the ground reaction force. In this case, if the ground is uniform, the pile penetrates into the ground only by rotating torque without applying a vertical pushing force. This is the same principle that a wood screw is screwed into a wood only by rotational force. Therefore, it is important to generate a propulsive force efficiently by the blades, and as shown in FIG. 34 (b), the traveling direction of the rotary penetrating steel pipe pile and the reaction force direction of the ground are made to coincide with each other, and Pushing up is the most efficient. In other words, it is most desirable that the blades be mounted substantially at right angles to the pile. On the other hand, as shown in FIG. 34 (a), in the case of the shape of the prior art, as shown in FIG. 34 (a), the blade (spiral bottom plate 41) is not perpendicular to the pile body, so that the propulsion force is increased and the workability is reduced. Is generated. From the viewpoint of the penetration mechanism and workability, it is desirable that the angle between the pile shaft and the blade is almost a right angle.

(2-6) Problems of Plastic Strain and Crack As in the above-mentioned Example 1 of the conventional type 3, the tip portion of the steel pipe pile is cut off in a spiral shape, and the tip end surface cut out in a spiral shape. Therefore, when welding a spiral blade that also serves as an excavating blade formed by bending a disk having a diameter larger than the steel pipe diameter, it is indispensable to make a cut in the radial direction up to the center of the disk. It has also been proposed to provide a small hole in the center of the disc. According to the description of the publication in the above embodiment, in the steel pipe pile 22 shown in FIGS. 23 to 27, an annular disk serving as the spiral bottom plate 23 is bent. In this case, when the diameter of the earth and sand entry hole 25 provided at the center of the disk is small, the surfaces ac and a′c ′ of the radial cut 26 are parallel to each other in order to attach the spiral blade and the pile shaft at a right angle. If it is attempted to form a helical shape as it is, the distortion due to the bending process on the inner side of the disk becomes excessive, and a crack is generated from the inner peripheral edge. The step between the start end ac and the end a′c ′ of the spiral bottom plate 23 formed by bending within a range in which no crack occurs becomes smaller on the inside than on the outside, and the surface of the radial cut 26 is an elevation projection. It will have a V-shape. This is also evident from FIGS. 23 and 24,
This shape indicates that the angle formed by the pile main body 22 and the spiral bottom plate 23 does not become a right angle when considering the vertical cross section of the pile passing through the steel pipe pile shaft. Conventional type 3-
According to the description of Japanese Patent Application Publication No. 2 (1995) -207, the manufacturing method of the spiral blade 33 shown in FIGS.
3 and the steel pipe 32 will not be at right angles. This is also apparent from FIGS. 29 and 30 showing the shape of the tip blade.

The above relationship will be described with reference to FIGS. In FIG. 36, (a) shows only the blades of the pile shown in FIG. 23 showing the first embodiment of the conventional type 3. (B) shows the start end ac and the end a'c 'of the blade.
(C) indicates that when the hole is enlarged, the crack is not generated even if the start end ac and the end a′c ′ are parallel. From FIG. 23, FIG.
6 (a), approximately Dw = 2Dp, Do =
It can be read that 0.2 Dp and the pitch at the steel pipe position is about 0.3 Dp. Here, Dw is the blade diameter, Do is the hole diameter at the center of the disk, and Dp is the steel pipe pile diameter. The perimeter before bending the blade of the hole in FIG. 36A = Doπ = 0.2Dpπ = 0.63Dp. For example, the diameter of the hole is 2.5 times (Do = 0.5Dp)
(FIG. 36 (c)) = 1.57 Dp. FIG. 37 is a developed view showing a state in which the circumference of the hole provided in the center of the disk is extended when the blade is spirally formed by bending and the start end ac and the end a′c ′ are parallel to each other. . Perimeter after bending of blade at Do = 0.2 Dp = 0.
Perimeter after bending of blade at 7Dp Do = 0.5Dp = 1.
6Dp. The distortion caused by the extension of the circumference by bending is Do =
At the time of 0.2 Dp, (0.7-0.63) /0.63=0.11 At the time of Do = 0.5 Dp, (1.6-1.57) /1.57=0.19 Calculating each ratio, 0.11 / 0.0
19 = 5.8. That is, when the pore diameter is 0.2 Dp,
Compared to the case where the hole diameter is 0.5 Dp, the distortion due to the bending of the blade reaches 5.8 times. From the above, it is apparent that if the hole at the center of the disk is small, the inner peripheral edge of the hole when the blade is spirally bent becomes excessively large, and a crack is easily generated.

In order to form a spiral blade while maintaining the parallel of ac and a'c 'in the radial cut 56 provided on the disk, when the pitch is 0.3 Dp, the center of the center It has been clarified by experiments of the present inventors that cracks are likely to occur when the diameter of the hole is less than half the diameter of the steel pipe pile. If the diameter of the hole at the center is larger than half the diameter of the steel pipe, cracks are unlikely to occur, but in this case, the area of the hole increases and it is considered that the hole belongs to the open-end pile.
It is desirable that the angle between the blades and the steel pipe is approximately a right angle. However, in the prior art, this has been realized only when the blades are fixed to the outer periphery of the steel pipe and only when the pile has an open end. In other words, in a closed-end pile fixed to the tip of a steel pipe whose blades are spirally cut off, there was no method of making the angle between the steel pipe and the blades substantially perpendicular.

(2-7) Problem of tip shape and tip steel pipe plate thickness Needless to say, steel pipe piles penetrate into a solid support layer consisting of underground gravel, sand, clayey soil, etc. It exerts a supporting force against the compressive force from above,
It is supported by the pile tip. In the case of the above-mentioned conventional types 1 and 2, since the blade is fixed to the outside of the steel pipe, the spiral blade has a shape like a cantilever, as shown in FIGS. A large bending moment acts on the steel pipe portion in the vicinity. In order to resist this bending moment, it is necessary to make the steel pipe at the part where the blade at the tip of the pile is fixed thicker than the plate thickness required from the supporting force. By comparison, 2
It is often up to about three times. When the required thickness of the steel pipe becomes extremely thick, there arises a problem that the cost of manufacturing the steel pipe also increases. As shown in FIG. 8A, the blades of the conventional type 3 are fixed to the tip of a steel pipe, and the blades protrude on the inner and outer sides of the steel pipe. Because of this, the bending moment due to the reaction force that the inner and outer blades receive from the ground respectively cancel each other at the connection position between the steel pipe and the blade, so the bending moment acting on the steel pipe is smaller than that of the conventional types 1 and 2 above. Considerably smaller. Therefore, the thickness of the tip of the steel pipe pile can be considerably reduced as compared with the conventional types 1 and 2. The thickness of the steel pipe depends on conditions such as the balance of the amount of protrusion of the blades on the inner and outer surfaces, but can be about the same as the thickness determined from the supporting force.

The following is a summary of the problems described above. (3-1) From the viewpoint of penetrability, it is preferable that the blade is fixed to the tip of a steel pipe cut in a spiral shape. (3-2) Further, it is desirable that the shape is such that earth and sand can enter the pipe during construction to reduce the penetration resistance. (3-3) It is desirable that the tip is a closed end from the viewpoint of supporting force. (3-4) It is desirable that the blades protrude largely inside the steel pipe from the plane of the thickness of the tip steel pipe. (3-5) Particularly from the construction side of the large diameter pile, it is desirable that the blades and the steel pipe are fixed at substantially right angles in order to use an existing construction machine capable of exerting a large torque. Further, from the viewpoint of the penetration mechanism, it is desirable that the blades and the steel pipe are fixed at substantially right angles in order to exert the propulsive force as effectively as possible. As shown in Table 1, in the prior art, a shape that satisfies all of these five points was not clarified, and the means for actually manufacturing the shape was unknown. The present invention provides a shape that satisfies all of these five conditions and means for realizing the shape.

[Table 1]

[0027]

As described above, the problem to be solved by the present invention is not disclosed in the prior art. Further, as described above, a rotary steel pipe pile applicable to everything from a small-diameter pile to a large-diameter pile and a construction method thereof have not been proposed. In particular, the present invention has a pile diameter of 1000 m
It is a rotary penetrating steel pipe pile that can be used for piles with a large diameter exceeding m, and that can sufficiently exhibit the supporting force as a pile.

According to a first aspect of the present invention, there is provided a steel pipe pile body having a spirally cut end,
A spiral penetrated steel pipe pile with blades that is composed of spiral blades fixed to the tip of the steel pipe pile main body in a shape corresponding to the spiral shape and is driven to rotate in the circumferential direction of the steel pipe pile main body and buried in the ground, The blades are formed from a disk-shaped member, and the blades exert a supporting force by being substantially closed and fixed to the hollow portion at the tip of the steel pipe pile main body, and the starting end and the end of the blades are formed in parallel, and during construction, It is characterized in that the penetration resistance is reduced by the earth and sand entering the steel pipe pile main body from the opening formed by the step between both ends. Since the tip of the steel pipe is almost closed with a spiral blade, it exerts sufficient supporting force equivalent to a closed-end pile, and the starting end of the blade becomes an excavation blade and projects to the shaft center of the steel pipe. Since it is pushed upward to enter the inside of the steel pipe, the penetration resistance during construction can be reduced. Further, since the starting end and the end of the spiral blade are bent so as to be parallel to each other, each surface of the blade is attached at right angles to the pile shaft.

According to a second aspect of the present invention, there is provided the rotary penetrating steel pipe pile according to the first aspect of the present invention, wherein the blade passes from a point on the outer periphery of the disk-shaped steel sheet through the center of the steel sheet, and the blade and the inner circumference of the steel pipe pile main body. It has a straight cut extending near the contact position and is formed spirally by bending. In other words, from one point on the outer periphery of the disk-shaped steel plate of the blade, passing through the center of the steel plate,
A cut is made near the contact position between the blade and the inner circumference of the steel pipe. Due to this radial cut, the portion from the one point on the outer periphery to the center of the steel pipe is made parallel between the two cut surfaces forming the beginning and end of the blade by bending, so that no step is formed without cracks. Can be provided. Earth and sand can be made to enter into the steel pipe at the time of construction from this step portion. In a steel plate in which this notch extends only to the center of the pile, if the radial cut surfaces at the beginning and end of the blade are parallel to form a step, and a spiral blade at a right angle to the side of the pile body is formed, In the center, plastic strain due to bending becomes excessive,
Cracks occur. Therefore, conventionally, FIGS.
5. As shown in FIGS. 28 to 30, the step portion has a V-shape, but as described above, the penetration of earth and sand into the pipe is small, and the degree of improvement in workability is small. The present invention solves these drawbacks of the conventional pile, achieves the same effects as the closed-end pile, and reduces the penetration resistance of earth and sand of the closed-end pile.

According to a third aspect of the present invention, there is provided the rotary penetrating steel pipe pile according to the first or second aspect of the present invention, wherein a portion of the blade protruding outside the outer periphery of the steel pipe pile main body and a shaft of the steel pipe pile main body. The angle is substantially a right angle. In addition to the reduction in the penetration resistance of the invention described above, by making the angle between the outer peripheral portion of the blade and the axis of the steel pipe pile main body a right angle, it is possible to efficiently obtain the penetration propulsion force. Large diameter piles can penetrate into a solid support layer with a small rotational force and a small propulsion force as compared with those in which the pile body axis is not substantially perpendicular. Furthermore, since the angle between the shaft of the steel pipe pile main body and the outer peripheral portion of the blade is substantially perpendicular, a grooved chuck collar necessary for constructing a large-diameter pile can be used. In this case, efficient construction can be performed using existing pile construction machines. It became possible to bend into such a shape, as described above, from one point on the outer periphery of the disk-shaped steel plate of the blade, passing through the center of the steel plate, near the contact position between the blade and the inner circumference of the steel pipe. This is the effect of cutting and bending up to a notch.

A fourth aspect of the present invention is the rotary penetrating steel pipe pile according to the first or third aspect, wherein the blade is formed by casting.

According to a fifth aspect of the present invention, in the first or the third aspect of the present invention, the blade has a straight line extending in a radial direction from the center axis of the pile main body at right angles to the center line and having a pitch around the center line. And is formed by casting into a spiral shape formed as a rotating body that can be rotated once while maintaining a right angle. By manufacturing the blade by casting, it passes through the center from one point on the outer periphery of the disk-shaped steel plate of the blade,
It is not necessary to make a cut near the position of contact with the inside of the steel pipe, and the reliability is further improved from the viewpoint of the supporting force.

According to a sixth aspect of the present invention, in the first or the third aspect, the blade is formed such that a straight line extending in a radial direction perpendicular to the center line of the pile main body axis and having a pitch around the center line, While maintaining a right angle, a spiral cut formed as a rotating body that can be made by one rotation is made with a linear cut extending from one point on the outer periphery of the disk-shaped steel sheet to near the center line, and the vicinity of the center line is required. Characterized by being formed by bending while being heated to a temperature of The blade in the first, second or third invention is not a cast product as in the fifth invention, but cuts into the vicinity of the center and further heats the vicinity of the center, so that no crack is generated. It can be manufactured by bending, and cost reduction can be achieved.

A seventh aspect of the present invention is the rotary penetrating steel pipe pile according to any one of the first to sixth aspects, wherein the thickness of the blade is changed in a radial direction in accordance with a bending moment distribution generated in the blade. It is characterized by becoming. This makes it possible to optimize the thickness of the blades and reduce the weight of steel,
Especially in the case of casting, the cost reduction effect is great.

An eighth invention is the rotary penetrating steel pipe pile according to any one of the first to seventh inventions, wherein the outer diameter of the blade is 1.5 to 3 times the outer diameter of the steel pipe pile main body, The step between the start and end of the spiral is 0.3 to 0.5 times the same outer diameter, and the angle between the start and end when the steel pipe pile body is looked up from the tip is 0 to 180 degrees. It is characterized by.

According to a ninth aspect, in the rotary press-fit steel pipe pile according to any one of the first to eighth aspects, a stepped portion at the beginning and end of the spirally cut end of the steel pipe pile is formed in an arc shape. And

The ninth invention will be further described. (1) The arc-shaped step portion is configured as a step portion 7 shown in FIG. (2) Since a large force is concentrated on the step portion at the beginning and end of the spirally cut steel pipe pile end at the time of rotary press-fitting, if this portion remains cut at an acute angle, as shown in FIG. Cracks may occur in the steel pipe of the pile body from the part. (3) This step is formed in an arc shape in order to alleviate stress concentration and prevent pile breakage.

According to a tenth aspect of the present invention, in any one of the first to ninth aspects, an inclined surface is provided on the fore-edge surface at the tip of the spiral blade so as to reduce resistance in the direction of rotation of the blade. The excavation blade is bonded to the fore-edge surface or the inclined surface by welding or the like, and the angle between the lower surface of the blade and the lower surface of the excavation blade is set to 135.
° to 170 °.

The tenth invention will be further described. (1) When the piles are rotationally press-fitted, as long as the N value of the ground is substantially uniform, there is no problem in penetrability even if the excavation blade is not provided at the tip. (2) When the N value of the ground increases rapidly, the blade cannot bite into the upper surface of the hard ground without the excavation blade, causing a slip phenomenon. (3) In order to prevent the sliding phenomenon from occurring, it is important to create a trigger for the spiral blade to bite into hard ground, and an excavation blade is required.

(4) Further, it is important that the excavation blade and the small face of the spiral blade have such a shape that the resistance decreases in the rotating direction of the blade. The required torque for rotation increases, and the workability deteriorates. (5) Therefore, it is desirable that the tip surface of the blade tip is provided with an inclination so as to reduce the resistance in the rotation direction of the spiral blade, and the excavation blade is bonded to the tip surface. (6) The angle between the lower surface of the cutting blade and the lower surface of the spiral blade is 13
The angle of 5 ° to 170 ° is effective. If the angle exceeds 170 °, the biting effect is not so high. If the angle is less than 135 °, the resistance at the tip becomes large, and the workability is deteriorated. (7) If the ground is such that the N value of the ground does not suddenly change, the excavation blade may not be necessary. When the change in the N value is small, an angle exceeding 170 ° may be sufficient in some cases. (8) The digging blade may be provided continuously or intermittently.

An eleventh invention is characterized in that the excavating blade according to the tenth invention is formed and adhered in such a shape as to extend over both the small or inclined surface at the tip of the blade and both surfaces of the lower surface of the blade.

The eleventh invention will be further described. When the pile is rotationally pressed, the ground is excavated by an excavation blade fixed to the tip of the blade. Therefore, the reaction force from the ground acts on the excavation blade, but the excavation blade
Alternatively, if the blade is fixed only to the lower surface of the blade, sufficient welding is required to prevent the excavation blade from being peeled off by the reaction force. On the other hand, if the excavating blade is fixed so as to straddle both the small edge surface or inclined surface of the blade tip and both surfaces of the blade lower surface, the contact surface between the excavating blade and the blade can resist the reaction force from the ground, so welding The amount can be reduced.

According to a twelfth aspect, a tubing device having a chuck collar or a chuck member provided with a concave groove corresponding to a pitch of a spiral blade is installed at a predetermined position on the ground.
A rotary penetrating steel pipe pile having a spiral blade fixed to a tip thereof according to any one of claims 1 to 11, and the spiral blade at the tip of the lifted rotary penetrating steel pipe pile is inserted into the groove of the chuck collar or the chuck member. Rotating the steel pipe pile shaft by the chuck collar or the chuck member to hold the steel pipe pile by rotating, rotating the chuck collar or the chuck member by a rotating device in the tubing apparatus, and rotating the steel pipe pile to drive the ground. This is a method for constructing a rotary penetrating steel pipe pile, which is buried inside.

According to the present construction method, since the outer peripheral portion of the blade protruding outward from the outer diameter of the steel pipe is formed substantially at right angles to the axis of the steel pipe in a radial manner, it is necessary to form the construction machine at a right angle. Is what you use. Conventionally, no method has been found in which the tip of the steel pipe pile is closed with blades and the angle between the steel pipe pile and the blades is almost right. Therefore, a shape similar to the conventional type 2 in which the blades are fixed to the outer peripheral surface of the steel pipe. This construction method could only be implemented in According to the present invention, it is possible to construct a large-diameter closed-end steel pipe pile by combining a construction machine used for excavating a hole in an existing cast-in-place concrete pile with a grooved chuck collar, and further, a ground reaction force received by a blade is provided. Since the direction coincides with the propulsion direction of the steel pipe pile, it is possible to efficiently construct a large-diameter steel pipe pile.

That is, according to the present invention, the tip of the steel pipe pile main body is almost closed by the spiral blade, so that the steel pipe pile exerts a sufficient supporting force equivalent to that of the closed-end pile, and the tip of the blade becomes an excavation blade and becomes a steel pipe. It protrudes to the shaft center of the pile main body, and the excavated earth and sand enters the inside of the steel pipe pile main body, so that the penetration resistance during construction can be reduced. Moreover, unlike the vertical drilling blade attached to the tip of the pile according to the prior art 3, the excavation of the soil by the starting end of the spiral blade cuts the soil and pushes it upward, so that the ground at the tip of the pile is not disturbed, and the bearing capacity is adversely affected. There is no. In addition to such a reduction in penetration resistance, the outer peripheral portion of the blade is formed substantially at right angles to the steel pipe pile main body, so even if the pile becomes large in diameter, efficient use of existing pile construction machines is possible. Construction becomes possible. Further, in any of the above shapes, the tip blades protrude greatly inside the steel pipe similarly to the closed end pile, so that the thickness of the tip steel pipe can be reduced.

The above is summarized as follows in comparison with the above five problems. On the penetrative surface, a spiral-shaped blade corresponding to the spiral is fixed to the tip of the steel pipe that has been spirally cut, and furthermore, the opening area of the step portion of the blade is maximized, so that the construction is completed. The earth and sand penetrate into the pipe and the penetration resistance can be reduced. In terms of the supporting force, the blades are in a closed end state when the blade is looked up from the front of the tip of the pile, and the reliability of the supporting force is secured. On the surface of the tip steel pipe plate thickness, the tip is in the closed end state as described above, and the moment in the steel pipe part is canceled out,
A reduction in plate thickness can be realized. In terms of connection with the construction machine, the blades of the portion projecting outward from the steel pipe and the shaft of the steel pipe are substantially perpendicular to each other, so that even a large-diameter pile can be efficiently constructed with the existing construction machine. In terms of the penetration mechanism, the blade and the steel pipe are fixed at substantially right angles as described above, so that the shape is such that the thrust can be exerted most effectively. That is, the present invention is an excellent invention that has solved all five problems of the prior art.

[0047]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 of the present invention is shown in FIGS.
This will be described with reference to FIG. FIG. 1 is a perspective view of the present embodiment. 2A, 2B, and 2C are a plan view, an elevation view, and a side view of the blade of the first embodiment, respectively.
2D and 2E are a sectional view taken along line AA and a sectional view taken along line BB of FIG. 2A, respectively. 3 and 4 illustrate the first embodiment.
And FIG. 5 is an explanatory view showing that the blades of the first embodiment of the present invention are perpendicular to the pile shaft, and FIG. 6 is a view showing the closing plate of the first embodiment. It is an explanatory view provided. Rotary penetration steel pipe pile 1 (hereinafter simply referred to as steel pipe pile 1)
Is composed of a steel pipe pile main body 2 (hereinafter simply referred to as a steel pipe 2) and a blade 3 integrated at its tip (lower end) by welding. In the example of FIGS. 1 and 2A, the blade 3 is made of a disk-shaped steel plate, the outer diameter of which is 2000 mm, and the diameter of the steel pipe is 1 mm.
000 mm. Therefore, the outer diameter of the blade is twice the outer diameter of the steel pipe. The blade diameter that is usually used is 1.
It is 5 times to 2 times, but the blade diameter can be increased up to about 3 times as needed.

Then, a linear cut 4 (width 100 mm) is provided from one point on the outer periphery of the blade 3 to the vicinity of the contact position between the blade 3 and the inner periphery 2a of the steel pipe 2 through the center of the steel plate. I have. The vicinity of the contact position is a range that passes through the center of the steel plate and extends from the center to at least 1/4 of the diameter of the steel pipe to the inner circumference 2a of the steel pipe 2. The width of the notch 4 provided in the blade 3 is desirably set to 0 from the viewpoint of the supporting force. However, considering the workability of the bending process, the width is 0.1 times the outer diameter of the steel pipe 2 (the same as in the present embodiment). It does not matter. The present inventors have found that if the width is about 0.1 times, there is almost no effect on the bearing capacity of the tip of the steel pipe pile 1 and the pile can be regarded as a closed-end pile. FIG. 3 is a perspective explanatory view clearly showing the differences between the present invention and the conventional example. The straight cuts 4 clearly show that the spiral blades 3 and the outer surface of the steel pipe pile are mounted at a right angle without cracking due to bending.
In this embodiment, the attachment is performed by welding. The lower part of FIG. 3 shows a conventional steel pipe pile provided with a hole at the center of the disk. It is shown that the blades are not perpendicular to the steel pipe pile body.

FIG. 4 shows a steel pipe 2 in comparison with the conventional example.
FIG. 4 is an explanatory view of the present embodiment, in which a start end and an end of an outer peripheral portion of a blade 3 projecting outward are formed so as to expand.
As is clear from FIGS. 1, 2 and 4, on the opening side of the cut 4, the starting end 5 and the end 6 of the cut 3a are formed symmetrically and distant from the extension of the cut 4, respectively. , 6 are set to 60 degrees. The angle formed by the start end 5 and the end 6 as an extension of the cut 4 is
The allowable range is 0 to 90 degrees, but about 30 to 4
It is desirable to set it to 5 degrees (30 degrees in the present embodiment). Therefore, the sandwiching angle is 60 to 90 degrees. From the viewpoint of the supporting force, it is desirable that the angle of each spread is 0 degree, but from the viewpoint of the workability of the steel pipe pile 1, it is desirable to form an angle of 0 to 90 degrees. However, this angle is not limited to a symmetric shape.

Until the ground on which the steel pipe pile 1 is constructed reaches the support layer, if all the grounds are very soft, the angle of each spread is 0.
Although there is no problem with the degree, if there is an intermediate layer with an N value of about 30 in the middle, or if it penetrates the gravel layer in the middle, etc., if the angle of each spread is 0 degree, it is between the start end 5 and the end 6 of the blade 3 Can be clogged with hard earth and sand and gravels, resulting in poor penetration. In order to avoid this, it is desirable that the start end 5 and the end 6 of the blade 3 have an angle of spread in a planar projection, and that the angle of spread be 90 degrees or less. If the angle of spread is made larger than this, the effect on the supporting force will be increased. Furthermore, considering that it is difficult to accurately grasp in advance the properties of the ground on which the steel pipe pile 1 is to be constructed, generally 30 to 45 respectively.
It is desirable to provide an angle of spread of about degrees.

Further, as shown in FIGS. 1 and 2, the blade 3 is bent into a spiral shape having substantially less than one turn. And the pitch of the spiral (the step between the start end 6 and the end 5) is 300 m
m, which is set to 0.3 times the outer diameter of the steel pipe 2 of 1000 mm. When this pitch is smaller than the pile diameter of 0.3, the propulsion force by the blades is reduced, and the workability is deteriorated. In addition, when the thickness of the blade is taken into consideration, the distance between the upper surface at the start end and the lower surface at the end of the blade in the pitch portion becomes smaller, and the pitch portion is likely to be clogged with earth and sand. If the pitch is larger than 0.5 times the pile diameter, the propulsion force is too large, and the construction torque is also increased. In particular, there is an inconvenience that construction cannot be performed with a large-diameter pile.
For medium and small diameter piles, the pitch can be increased to about 0.6 times the pile diameter. In addition, FIG.
As shown in (d), (e) and FIG. 5, the outer peripheral portion 3a of the blade 3 protruding outside the outer diameter of the steel pipe 2 is formed from one point on the outer circumference of the blade toward the center of the pile steel pipe. The straight line drawn along the upper surface and the axis of the steel pipe 2 are formed so as to be substantially perpendicular to each other, and the start end ac and the end ac of the spiral are formed substantially parallel. As a result, a step 7 (opening 7) is formed between the start end 6 and the end 5 of the spiral. Then, the tip of the steel pipe 2 is processed into a shape corresponding to the spiral shape of the blade 3, and is welded concentrically with the blade 3. Thus, the steel pipe pile 1 is configured as shown in FIG.

As apparent from FIGS. 1 to 4, the steel pipe pile 1
Can be regarded as a closed-end pile because the stepped portion 7 of the blade 3 is open at the tip end surface within the outer diameter of the steel pipe 2 and is almost closed. The same bearing capacity as the end pile is exhibited. In addition, since the blades protrude inside and outside the steel pipe, and the inside protrusion completely covers the steel pipe, the moment acting on the steel pipe is reduced, and the steel pipe plate thickness can be reduced. When the blades 3 are driven to rotate together with the steel pipe 2, earth and sand enter the steel pipe 2 from the opening 7 between the start end 6 and the end 5 of the spiral, so that the penetration resistance (drive torque) of the steel pipe pile 1 is reduced. Mitigated, in this regard,
It can be regarded as an open-end pile, and almost the same workability as an open-end pile is exhibited. In the prior art, the start end ac and the end a ′
Since c ′ is not perpendicular to the axis of the steel pipe 2, the opening bccb between the start and end is V-shaped (the axial center side of the steel pipe 2 is narrow, and the blade 3
(The outer peripheral side is wide), the area of the opening 7 was small, and almost no earth and sand entered the inside of the steel pipe pile 1 during construction. In the present invention, the starting end ac of the blade 3 at the step portion
And the end a′c ′ can be parallel to each other, and the area of the opening 7 therebetween can be increased, so that the earth and sand can enter the inside of the steel pipe 2 from the opening 7 of the stepped portion during construction. it can. Thereby, the penetration resistance of the pile tip at the time of construction is reduced, and even if the steel pipe pile 1 has a large diameter, the construction efficiency of the pile is not reduced.

As shown in FIG. 6, the area of the triangle surrounded by cdc in the opening 7 may be closed by the closing plate 10. By doing so, the stress can be transmitted to the step portion of the blade, and the effect of reducing the thickness of the steel tube plate is further enhanced.

As described above, when the blade is fixed to the outside of the steel pipe, the spiral blade is shaped like a cantilever as shown in FIGS. A large bending moment acts on the steel pipe part of the steel pipe, and the steel pipe main body 2 is deformed inward. As shown in FIG. 8A, the blades of the conventional type 3 are fixed to the tip of a steel pipe, and the blades protrude on the inner and outer sides of the steel pipe. FIG. 8 also shows the present invention.
As shown in (b), the blades project on the inner and outer sides of the steel pipe, so the bending moment due to the reaction force received by the inner and outer blades from the ground cancel each other at the connection position between the steel pipe and the blade. The bending moment acting on the steel pipe is quite small, and the thickness of the tip of the steel pipe pile is about the same as the thickness determined from the supporting force, depending on conditions such as the balance of the amount of overhang of the blades on the inner and outer surfaces. It is also possible to use Further, since a large force is concentrated on the stepped portion at the beginning and end of the spirally cut steel pipe pile end at the time of press-fitting, if this portion is cut at an acute angle, as shown in FIG. Cracks may occur in the steel pipe of the pile body due to Therefore, in order to reduce stress concentration and prevent breakage of the pile, the arc-shaped step portion is configured as a step portion 7 shown in FIG.

As shown in FIGS. 1 and 5, the present invention is applied to an outer peripheral portion 3a of a blade 3 protruding outside the outer diameter of a steel pipe 2.
Are formed almost radially at right angles to the axis of the steel pipe 2. As a result, a construction method using a construction machine that needs to be formed at a right angle has become possible. conventionally,
The tip end of the steel pipe pile 1 is closed by a blade, and the steel pipe pile 1
No method has been found in which the angle between the blade and the blade 3 is made substantially a right angle. Since this problem is solved by forming the blades 3 at right angles as described above, the construction of the large-diameter steel pipe pile 1 can be performed by using an existing construction machine, and the ground resistance of the blades 3 Since the direction of force coincides with the direction in which the steel pipe pile 1 is propelled, the large-diameter steel pipe pile 1 can be constructed efficiently. That is, FIG.
Instead of using the construction machine 60 shown in FIG. 8, as shown in FIG. 39, a construction machine 70 of a type in which the steel pipe pile main body 70 is gripped from the outside and rotated, and a grooved chuck collar 74 shown in FIG. It is now possible to adopt the construction method used. As described above, since the construction machine 60 can exert a small torque, it cannot cope with the construction of a large diameter pile. Therefore, it is necessary to use a construction machine 70 capable of exerting a large torque for constructing a large diameter pile. When this tubing device 70 is used, it is necessary to use a grooved chuck collar or grooved chuck member in which a groove corresponding to the size of the blade diameter and the helical pitch of the blade is formed.

The grooved chuck collar shown in FIG. 10 will now be described. In the conventional method without using the grooved chuck collar, the rotary penetrating steel pipe pile has a tip blade diameter much larger than the pile steel pipe diameter. For mounting the pile on the tubing device, insert the rotating penetrating steel pipe pile into the tubing device installed on the ground without attaching the chuck collar, and then attach the chuck collar (without groove) lifted by the crane to the chuck device. First, the rotating penetrating steel pipe pile is placed on the ground using the construction machine 60, and the tubing device 70 to which the chuck collar (without groove) is attached in advance is lifted by a crane, and is placed over the rotating penetrating steel pipe pile. The construction method of installation was adopted.
In the former method, a plurality of chuck collars must be inserted and fixed between the rotary penetrating steel pipe pile and the chuck device,
The work process was very troublesome. The latter method has the drawback that the heavy tubing device 70 is lifted to a high position, which involves danger, requires a crane with a large capacity, and requires a long time due to careful installation work. Was. If the grooved chuck collar and the grooved chuck member are used, the process of mounting the rotary penetrating steel pipe pile on the tubing device can be simplified and efficiently performed. In the case where the grooved chuck collar is used, the mounting of the pile can be completed in about several minutes, whereas the above two methods require 30 minutes to 1 hour. Even if the collar does not have a groove, if the gripping part has a structure that can be opened and closed wider than the blade diameter, a pile with blades can be inserted from the upper side of the tubing device without using a chuck collar. The construction machine having the construction machine has not been put to practical use, and the inventors of the present application have conducted similar studies. As a result, the construction machine was considerably complicated and large, which was impractical. In the current technology, a grooved chuck collar is the most excellent for efficiently constructing a large bladed rotary penetrating pile, and the pile side has a shape that can use the grooved chuck collar. It is desirable.

As shown in FIG. 10, the groove of the chuck collar corresponds to the spiral shape of the blade of the rotary penetrating steel pipe pile. When the pile is hung from above and rotated by human power, the blade passes between the grooves. It is necessary that the spiral blade is fixed substantially at right angles to the shaft of the steel pipe. When the blades are not perpendicular to the pile steel pipe, it is necessary to widen the groove of the chuck collar, but the projection becomes thinner accordingly. This projection holds the pile steel pipe,
It is necessary to transmit the rotational force and, if necessary, the push-in force and the pull-out force. If the root of the projection is thinner than the current state, the strength and rigidity for transmitting these forces will be insufficient. In addition, when the area of the tip of the convex portion is small, the pressure acting on the pile when gripping the pile increases, and there is a problem that the pile steel pipe is damaged. The use of the grooved chuck collar or chuck member makes the construction of a large-diameter pile extremely efficient, but for that purpose, the spiral blade had to be mounted almost at right angles to the pile shaft. . That is,
For the construction of a large-diameter rotary penetrating pile, it is essential that the pile shaft and the blade are fixed at substantially right angles. According to the present invention, for the first time, this tubing device is used in a large-diameter closed-end pile. The construction method has been realized.

In the embodiment of the present invention, FIG.
As shown in (A) to (F), the excavation blade 14 is provided on the fore-edge surface 13 at the tip of the spiral blade 3 or the inclined surface 17 provided on the fore-edge surface.
18 are provided. The inclined surface provided on the fore-edge surface is provided so as to reduce the resistance in the rotational traveling direction of the spiral blade 3. The excavating blades 14 and 18 are joined to the fore-edge surface 13 or the inclined surface 17 by a method such as welding. In the case of the illustrated example, the angle θ between the lower surface of the blade and the lower surfaces of the digging blades 14 and 18 is set to approximately 135 in order to impart the above-mentioned inclination to the spiral blade 3.
° to 170 °.

Referring to FIG. 12 in order, FIG.
In (B), the excavating blade 14 has a substantially mountain-like shape in which the top portion 15 is located slightly outward from the middle, and its base end surface is welded to the vertical small surface 13 at the tip of the blade.
° to 170 °. FIGS. (C) and (D) are modified examples of the excavating blade 14 shown in FIGS. (A) and (B), in which the upper part of the blade tip is inclined, and the excavation is performed on the small face 13 of the inclined tip. The base end surface of the blade 14 is welded, and is provided so that the inclined surface of the blade tip and the inclined surface of the upper surface of the excavating blade 14 are connected.

FIGS. 12E and 12F show still another modification of the excavation blade. In this example, the tip of the blade has a substantially mountain-like shape in a plane, and an inclined surface 17 is formed on the tip 16 of the mountain-like shape. An example is shown in which θ is set to approximately 135 ° to 170 ° and welding is performed.

FIGS. 13A to 13C show other examples of the planar shape of the blade tip. FIG. 4A shows an example in which a knife-like inclined surface 19 with a sharp inner peripheral side is integrally formed as a digging blade at the blade tip, and FIGS. 4B and 4D show the same. FIG. 5C shows an example in which a digging blade 14 having the same structure is formed in a substantially mountain-like shape having a top portion 15 in the middle. In FIG. 5C, a knife-like inclined surface 19 having a sharp inner peripheral side is formed at the tip of the blade. An example in which a knife-shaped excavating blade 20 is welded to the inclined surface 19 is shown. The shape of the digging blade may be something other than the illustration.

FIG. 14 (a) is a plan view of a digging blade attached to the tip of the blade, and (b) and (c) show the bonding of the digging blade so as to straddle both the small face of the blade and the lower surface of the blade. FIG. 2 is a detailed view of an embodiment of the present invention and a digging blade. (D)
The reaction force from the ground (R1, R
This shows a resistance mechanism for 2). (D) In the left figure, R2 is resisted by the force of R2 ', but R1 is resisted only by the welded portion.
On the other hand, (d) in the right diagram, resistance can be applied to R1 and R2 with the forces of R1 ′ and R2 ′, respectively, so that the welding amount can be reduced. FIG. 15A shows a state in which the amount of protrusion of the blade from the joint between the tip of the steel pipe and the blade is minimized. FIG. 15B is a diagram showing a state in which the blades are swollen by the force acting during the construction when the protrusion amount is large. Due to the reaction force from the ground accompanying the excavation of the ground during the construction, a force acting on the blades to tear off from the end face of the steel pipe may act, and the welding of the steel pipe and the blade may be broken. Therefore, it is desirable that the protruding length is set to a minimum length necessary for welding the blade and the steel pipe as shown in FIG. Thus, depending on the condition of the ground, it is desirable to provide a digging blade at the blade start end, and the shape is shown in FIG. The presence of the blade improves biting into the ground at the tip and improves workability. In particular, when it is necessary to penetrate the pile from a soft layer to a hard support layer such as an L-type ground, or when the soft layer and the hard layer are alternated, the effect of the excavation blade is great. .

The thickness of the blades 3 does not need to be the same as a whole, but is changed in the radial direction of the blades 3 according to the bending moment generated by the force acting on the blades 3. As conceptually shown in FIG. 16, a method in which a portion close to the steel pipe 2 is formed into two blades 3 b is considered. However, since the spiral blade 3b is disadvantageous in processing, the thickness of the blade 3c is continuously changed by casting as shown conceptually in FIGS. 17 (a), (b) and (c), for example. , 3d,
The method 3e is advantageous. At this time, when the upper surface of the blade 3 is inclined, the propulsive force of the blades 3d and 3e is shifted from the vertical direction. However, since the inclination is as small as the thickness of the blade, the effect on the propulsive force is small. 16 and 17 do not show the pitch of the blades to show the concept.

A second embodiment of the present invention will be described with reference to FIGS. In the second embodiment of the present invention, the blade to be bonded to the tip of the steel pipe pile main body is manufactured by casting.
FIGS. 18 (a), (b) and (c) show the second embodiment of the present invention, respectively.
It is a plan view, an elevation view, a side view of the blade of the embodiment,
(D) and (e) are a CC sectional view and a DD sectional view of FIG. 18 (a), respectively. FIGS. 19A and 19B are a longitudinal side view and a bottom view of the second embodiment. FIG.
It is a perspective view of an embodiment. In this figure, the blade is cc
Is the main part of the fan, and the fan is expanded 360 °. The blade of the first embodiment can be manufactured by casting, and when manufacturing the blade by casting, the shape of the blade can be freely formed, and the thickness of the blade is changed according to the bending moment. 3 can be used. The concept of blade thickness determined according to the bending moment generated in the blade is shown in Fig. 1.
It is shown in FIG. In producing the casting blade, the cc portion may be formed in a rod shape for convenience of production. Or 0.
A hole having a diameter of about 1D (D is a pile diameter) or less may be used.

This shape is generally considered to be easier to produce by casting, but if the cc portion is heated to the required temperature and then bent, it can be processed without causing plastic strain and cracks. Thus, the cost can be improved.

[0066]

As is apparent from the above description, according to the present invention, since the opening at the tip of the steel pipe pile main body is almost closed, the supporting end is in the closed end state, It has almost the same reliability for bearing capacity as piles. At the time of construction, by maximizing the opening area of the stepped part of the blades, earth and sand enter the steel pipe pile main body from the opening, so the penetration resistance of the steel pipe pile is reduced, and the workability is almost the same as open-ended pile Be demonstrated. In addition, the notch provided in the blade at the tip of the steel pipe pile main body has a small effect on the obstruction at the tip, and the cut can increase the opening at the beginning and end of the spiral. The construction efficiency is excellent. In terms of the penetrating mechanism, the blades and the steel pipe are fixed at substantially right angles by the cuts provided in the blades, so that the shape is such that the thrust can be exerted most effectively.

Further, since the excavating blade is adhered so as to straddle both the small face of the blade and the lower surface of the blade, it is possible to suppress the reaction force from the ground during excavation and to promote excavation. In addition, the thickness of the blade can be changed in the radial direction according to the distribution of the bending moment generated in the blade, thereby ensuring the strength. On the surface of the steel pipe plate thickness, the tip is in the closed end state as described above, and since the blades protrude inside the steel pipe, the bending moment at the steel pipe tip is eliminated, so that the reduction in the plate thickness is reduced. realizable. In addition, by casting the blade, it is possible to easily manufacture the present shape. Further, by heating the vicinity of the center, it is possible to further easily manufacture the present shape.

In terms of the construction method, the blades of the portion protruding outward from the steel pipe and the shaft portion of the steel pipe are substantially perpendicular to each other, so that even large-diameter piles can be efficiently constructed using existing construction machines. That is, compared with the conventional technology, the reliability of the tip support force, which is the most important issue, is increased, enabling the efficient construction of large-diameter steel pipe piles of 1000 mm or more, and reducing the thickness of the pile tip steel pipe. It has an excellent effect of realizing.

[Brief description of the drawings]

FIG. 1 is a perspective view of a first embodiment.

FIGS. 2A, 2B, and 2C are a plan view, an elevation view, and a side view, respectively, of the blade according to the first embodiment of the present invention;
(D) and (e) are AA sectional view and BB sectional view of FIG. 1 (a), respectively.

FIG. 3 is a perspective explanatory view comparing the first embodiment of the present invention with a conventional example.

FIG. 4 is a perspective explanatory view comparing the first embodiment with a conventional example.

FIG. 5 is an explanatory diagram of an angle between a steel pipe pile shaft and a spiral blade according to the first embodiment of the present invention.

FIG. 6 is an explanatory diagram showing a closing plate according to the first embodiment of the present invention.

FIG. 7 is an explanatory view showing a bending moment acting on a blade and a steel pipe main body in a conventional example.

FIG. 8 is an explanatory view showing a bending moment acting on the blade and the steel pipe main body in the present invention.

FIG. 9 is a view showing cracks generated in a step portion in a conventional example.

FIG. 10 is a detailed view of a tubing device used in the present embodiment.

FIG. 11 is a view showing a cutting blade of the present embodiment.

FIG. 12 is a view showing a cutting blade according to the embodiment;
(A), (B) is a perspective view and a cross-sectional view of a first example of a digging blade,
(C), (D) is a sectional view of a second example and a third example of the excavation blade,
(E), (F) is a perspective view and a cross-sectional view of a fourth example of the excavation blade.

FIGS. 13A, 13B, and 13C are explanatory views showing still another three examples of the excavation blade.

14 (a), (b), and (c) are detailed views of the excavating blade of the present invention, and (d) is an explanatory view showing the operation of the excavating blade of the present invention bonded to the tip of a spiral blade. is there.

FIG. 15 is an explanatory view showing a bonding position between the excavation blade at the tip of the spiral blade and the tip of the steel pipe according to the present invention.

FIG. 16 is an explanatory diagram showing the thickness of the blade of the present embodiment.

FIG. 17 is an explanatory diagram showing the thickness of the blade of the present embodiment.

FIGS. 18 (a), (b), and (c) are a plan view, an elevation view, and a side view, respectively, of a blade according to a second embodiment of the present invention;
(D) and (e) are a CC sectional view and a DD sectional view of FIG. 18 (a), respectively.

FIGS. 19 (a) and (b) are a longitudinal side view and a bottom view of the second embodiment.

FIG. 20 is a perspective view of the second embodiment.

FIG. 21 is a conceptual diagram of prior arts 1, 2, and 3.

FIG. 22 is an explanatory diagram of Conventional Technique 1.

FIG. 23 is an explanatory diagram of Conventional Technique 3.

FIG. 24 is an explanatory view showing an operation of an opening according to Conventional Technique 3.

FIG. 25 is an explanatory view showing a closing plate according to Prior Art 3;

FIG. 26 is an explanatory diagram of a digging blade provided on a bottom plate according to Conventional Technique 3.

FIG. 27 is an explanatory view of a digging blade provided on a bottom plate of the conventional technology 3;

FIG. 28 is an explanatory view showing another example of the conventional technique 3.

FIG. 29 is an explanatory view of forming a spiral blade with a circular steel plate of another example of the related art 3.

FIG. 30 is an explanatory view showing a cut in another example of the conventional technology 3;

FIG. 31 is an explanatory view showing an angle between a blade and a pile shaft according to the conventional technique 3.

FIG. 32 is an explanatory view showing an angle formed by a blade and a pile shaft according to the conventional technique 3;

FIG. 33 is an explanatory view showing a closing member of prior art 3.

FIG. 34 is an explanatory diagram of a penetration mechanism.

FIG. 35 is an explanatory view showing an angle between a blade and a pile shaft according to a conventional technique.

FIG. 36 is an explanatory diagram of a phenomenon in which cracks occur when a blade and a pile axis are perpendicular to each other in the related art.

FIG. 37 is an explanatory view of a phenomenon in which cracks occur when a blade and a pile axis are perpendicular to each other in the conventional technique.

FIG. 38 is a view showing a conventional construction machine.

FIG. 39 is a view showing a construction machine used in the present invention.

[Explanation of symbols]

 Reference Signs List 1 steel pipe pile 2 steel pipe (steel pipe pile main body) 2a inner diameter of steel pipe 3 spiral blade 3a outer peripheral portion of blade 3b double-layer blade 3c, 3d, 3e cast blade 4 cut 5 spiral end 6 spiral start 7 step (Opening portion) 8 Cutting inner blade 9 Cutting outer blade 10 Closing plate 11 Corner portion 12 Crack 13 Small edge 14 Drilling blade 15 Top 16 Mountain-shaped tip 17 Inclined surface 18 Drilling blade 19 Knife-shaped inclined surface 20 Drilling blade 22 Steel pipe (Steel pipe pile main body) 23 Spiral blade 24 Excavation blade 25 Sediment entry hole 26 Cut 27 Close plate 28 Drilling blade 29 Bottom plate 32 Steel pipe (Steel pipe main body) 33 Spiral blade 34 Cut 35 Close plate 36 Opening 42 Steel pipe (Steel pipe main body) 43 spiral blade 53 spiral blade 56 cut 70 tubing device 73 rotating pile 73b drilling blade 74 chuck collar 75 casing Tube rotating device 78 Chuck device a: Blade start end outer circumference (when the start end angle = 0) b: Contact point between blade start end and pile steel pipe c: Point closest to blade start end and pile center a ': Blade end outer circumference b': Blade Contact point between end and pile steel pipe c ': Point closest to blade end and pile center ac: Radial cut surface at blade start end a'c': Radial cut surface at blade end R1: Reaction force R2: Reaction force

Claims (12)

[Claims] 1. A steel pipe pile main body having a tip notched in a spiral shape, and a spiral blade fixed to the tip of the steel pipe pile main body in a shape corresponding to the spiral shape. In a rotary penetrating steel pipe pile with blades, which is driven to rotate and is buried in the ground, the blades are formed of a disc-shaped member, and the hollow portion at the tip of the steel pipe pile body is substantially closed and fixed to exhibit supporting force. In addition, the starting end and the end of the blade are formed in parallel, and at the time of construction, penetration resistance is reduced by earth and sand entering the steel pipe pile main body from an opening formed by a step between both ends, thereby reducing the penetration resistance. . 2. The blade has a straight notch extending from a point on the outer periphery of the disk-shaped steel sheet, passing through the center of the steel sheet, and reaching near a contact position between the blade and the inner periphery of the steel pipe pile main body, and is formed by bending. The rotary penetrating steel pipe pile according to claim 1, wherein the pile is formed in a spiral shape. 3. The rotary penetration according to claim 1, wherein an angle formed between a portion of the blade protruding outside the outer periphery of the steel pipe pile main body and an axis of the steel pipe pile main body is substantially perpendicular. Steel pipe pile. 4. The rotary penetrating steel pipe pile according to claim 1, wherein the blade is formed by casting. 5. The blade is formed as a rotating body formed by rotating a straight line extending in a radial direction at right angles to the center line of the pile main body from the center line of the pile main body with a pitch around the center line while maintaining the right angle. The rotary penetrating steel pipe pile according to any one of claims 1 to 3, wherein the spiral shape is formed by casting. 6. A rotating body in which the blade is formed by rotating a straight line extending in a radial direction at right angles to the center line from the center line of the pile main body with a pitch around the center line while maintaining the right angle and one rotation. In the spiral shape formed as, a linear cut extending from one point on the outer periphery of the disc-shaped steel plate to near the center line,
2. The semiconductor device according to claim 1, wherein the center line is formed by bending the vicinity of the center line while being heated to a predetermined temperature.
Or the rotary penetration steel pipe pile in any one of 3. 7. The rotary penetrating steel pipe pile according to claim 1, wherein a thickness of the blade is changed in a radial direction in accordance with a bending moment distribution generated in the blade. 8. The outer diameter of the blade is 1.5 to 3 times the outer diameter of the steel pipe pile main body, and the step between the start and end of the spiral is 0.3 to 0.5 times the outer diameter. The opening angle of a part which protrudes outward from the outer periphery of the steel pipe main body at the start end and the terminal end when the steel pipe pile main body is looked up from the front end is 0 to 180 degrees. A rotary penetrating steel pipe pile described in Crab. 9. A stepped portion at the beginning and end of a tip end portion of a steel pipe cut in a spiral shape is formed in an arc shape.
A rotary press-fit steel pipe pile according to any one of Items 1 to 8. 10. A method in which an inclined surface is provided on the small face at the tip of the spiral blade so as to reduce resistance in the direction of rotation of the spiral blade, and a drilling blade is welded to the small face or the inclined surface. The rotary press-fit steel pipe pile according to any one of claims 1 to 9, wherein an angle between the lower surface of the blade and the lower surface of the excavation blade is approximately 135 ° to 170 °. 11. The rotary press-fit steel pipe pile according to claim 10, wherein the excavating blade is formed and adhered in such a shape as to extend over both the small edge surface or the inclined surface of the blade tip and both surfaces of the blade lower surface. 12. A tubing device having a chuck collar or a chuck member provided with a groove corresponding to a pitch of a spiral blade is installed at a predetermined position on the ground.
1. The rotating penetrating steel pipe pile having a spiral blade fixed to the tip thereof according to any one of (1), and the lifted spiral blade at the tip of the rotating penetrating steel pipe pile is inserted and rotated into the groove of the chuck collar or chuck member. By passing through, the steel pipe pile shaft portion is clamped and gripped by the chuck collar or the chuck member, and the chuck collar or the chuck member is rotated by a rotating device in the tubing device, and the steel pipe pile is rotationally driven and buried in the ground. A method for constructing a rotary penetrating steel pipe pile, characterized in that: