JP2003096772A - Screw type steel pipe pile and its work method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a screw type steel pipe pile and its work method capable of making easier to penetrate the pile into a supporting layer, permitting to make a larger diameter and achieving a sufficient ground supporting capacity. SOLUTION: A spiral type wing or a sloped flat plate is placed on the side surface, and a lid body which is destroyed or disassembled by a force in downward direction is constituted at the end portion. And when the screw type pipe pile is penetrated to a predetermined depth, a bucket is inserted to the inside, and the lid body is pushed in downward direction thereby destroying or disassembling the lid body in the first process, the ground is further excavated by the bucket in the next process, the bucket is pulled out from the screw- type steel pipe pile in the next process, and then foot protection concrete is poured in the excavated range in the next process as the feature of this method.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a screw-in type steel pipe pile, and more particularly to a screw-in type steel pipe pile having a closed front end and a method for constructing the same.

[0002]

2. Description of the Related Art Steel pipe piles or concrete piles (hereinafter referred to as "tips") in which a lid-like member is attached to the opening at the tip end to prevent earth and sand from entering inside when a steel pipe pile or the like penetrates into the ground There are several proposals for blocking piles). In addition, the construction method of this tip closed pile, hitting method to hit the head of the pile body to penetrate into the ground, excavate a hole in the ground to install the pile body in advance, and install the pile body in the hole There is a pre-boring method, or a method in which the pile body is rotationally buried by the action of the wood screw of the wing attached near the tip of the pile body. Furthermore, an invention has also been proposed in which a steel pipe pile with an open tip is dug and concrete is placed only at the tip.

[0003] Several methods of burying the pile body by rotation by the action of a blade attached to the vicinity of the tip of the tip closed pile have been put into practical use for steel pipe piles of small diameter.

FIG. 8 is a side view showing a conventional steel pipe pile disclosed in Japanese Patent Publication No. 2-62648. In FIG. 8, the steel pipe pile 100 has a bottom plate 102 on the lower surface of the pile body 101.
The bottom plate 102 is provided with a drilling blade 104, and the outer peripheral surface of the lower end portion of the pile main body has an outer diameter of approximately 2 mm.
Spiral blade 1 for screwing in, which has a double outer diameter and a large span
03 is projected over almost one volume. Therefore, the steel pipe pile 100 is pressed into the ground while being rotated so as to be screwed into soft ground, and the earth and sand located at the tip of the pile body 101 is excavated and softened by the excavation blade 104 at the lower end, and the unexcavated earth and sand on the side surface of the pile is excavated. The spiral wing 103 bites into the pile main body 101 by rotating the pile main body 101 as a reaction force, and the excavated and softened earth and sand is pushed out to the side surface of the pile and compressed, and the steel pipe pile 100 is screwed into the ground without discharge. This is done (hereinafter, referred to as prior art 1).

FIG. 9 is a side sectional view showing a conventional steel pipe pile disclosed in Japanese Patent Publication No. 4-58850. In FIG. 9, a steel pipe pile 200 includes a bottom plate 20 having a drill body 204 and a grout jet 203 at the lower end of a pile body 201.
The spiral blade 205 having an outer diameter that is almost twice the outer diameter of the pile body 201 is fixed to the outer peripheral surface of the lower end of the steel pipe pile by one turn. In addition, the steel pipe pile 200 is configured such that cement milk is jetted from the grout jet port 203 during and after the rotary burying to reinforce the circumferential ground. Therefore, as in the case of the prior art 1, the steel pipe pile 200 is screwed into the ground without discharging soil, and cement milk is jetted from the grout jet port during and after the rotary embedding to surround the ground surface (of the pile body 201). The peripheral support layer 208 located on the side surface and the root consolidation nodule 20 located at the lower end portion
9) is strengthened (hereinafter, referred to as prior art 2).

[0006]

However, the construction method according to the prior art 1 has been widely put into practical use in the range where the outer shape of the steel pipe pile is less than 300 mm. This burying method can secure a comparatively large tip supporting force because the tip of the steel pipe is closed by the bottom plate, but the reaction force received by the spiral blade from the ground is large, so that it particularly penetrates into the supporting layer. In doing so, not only the torque required for rotary penetration becomes very large, but also the penetration efficiency deteriorates. According to the field test conducted by the inventors, the torque required for supporting layer penetration increases to 3 to 5 times the torque for soft ground penetration.

Therefore, a motor having a large capacity for rotating the pile body and a base machine for mounting the motor are required, and the torsional moment of the pile body becomes large, so that the thickness is larger than the thickness required for design. In many cases, a thick steel pipe is required for construction. Also, concrete piles that are weak in torsion cannot be applied. Furthermore, the outer diameter of the steel pipe is 6
If it exceeds 00 mm, the torque required for construction becomes too large and a special large machine is required, which is not practical.

In the method for burying steel pipe piles according to the prior art 2, since cement milk is jetted from the tip of the pile body and stirred and mixed with earth and sand by the spiral blade, the disturbance of the support layer ground by the spiral blade is recovered to some extent. However, since the rotation for stirring and mixing is in only one direction of the spiral blade, sufficient stirring of the soil and cement milk cannot be expected. Especially when the ground is cohesive soil,
Stirring tends to be non-uniform.

Although the rotating torque can be slightly reduced as compared with the case where the cement milk is not ejected, the rotating torque cannot be expected to be greatly reduced because the earth and sand in the vicinity of the tip of the blocked pile is difficult to move. Further, since the range of stirring and mixing of the sand and sand is only the spiral blade portion, only the ground supporting force corresponding to the projected area of the spiral blade can be expected.

The present invention has been made to solve the above-mentioned problems, and provides a screw-type steel pipe pile capable of easily penetrating into a support layer and exhibiting sufficient ground support capability, and a method for constructing the same. The purpose is to do.

[0011]

Means for Solving the Problems A screw-in type steel pipe pile of the present invention for solving the above problems is as follows. [1] A screw-in type steel pipe pile is characterized in that a lid body that is broken or decomposed by a downward force is installed at a lower end portion thereof.

Further, the method of constructing the screw-in type steel pipe pile of the present invention is as follows. [2] In a screw-type steel pipe pile, a step of installing a lid body that is broken or decomposed by a downward force at the lower end thereof, a step of rotating the screw-type steel pipe pile and penetrating into the ground, Where it penetrates to the depth, inserting a bucket into the screw-in steel pipe pile, the step of destroying or disassembling the lid by pushing the lid downward, and the step of further excavating the ground by the bucket And a step of extracting the bucket from the screw-in type steel pipe pile, and a step of placing rooting concrete in the excavated area.

[3] In the above [2], the screw-in type steel pipe pile is further rotated and penetrated before, in parallel with or after the step of pouring the concrete for consolidation.

[4] In [2] or [3], the earth and sand excavated by the bucket is poured onto the cast concrete.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION [First Embodiment] (Screw Type Steel Pipe Pile) FIG. 1 is a perspective view of a partial cross section for explaining an embodiment of a screw type steel pipe pile according to the present invention. In FIG. 1 (a), 1 is a screw-type steel pipe pile (hereinafter referred to as steel pipe pile 1), 2 is a steel pipe whose both ends are open, 3
Is installed on the inner peripheral surface near the tip of the steel pipe 2, so screws 4
Is a substantially spiral blade installed on the outer peripheral surface of the steel pipe 2 near the tip thereof. Reference numeral 6 is a lid that closes the opening of the front end of the steel pipe 2, and an external thread 7 that is screwed into the internal thread 3 is provided on the outer periphery of the lid, and can be easily fixed to the steel pipe 2. The lid 6 is made of a brittle substance such as concrete, and has radial slits 6a formed on the lower surface side when fixed to the steel pipe 2.

Therefore, although the bottom of the slit can be compressed and endured against the ground reaction force from the lower surface, tensile stress is generated in the slit bottom against the load from the upper surface, and the crack easily develops to cover the lid. The structure is such that the body 6 is easily destroyed.

The present invention is not limited to the radially arranged slits, but the slits may be arranged in a grid pattern, and the cross-sectional shape of the slits may be rectangular or triangular. Further, the slits are compressed. Power transfer padding may be installed.

FIG. 1 (b) is a modification of the lid body 6 with slits shown in FIG. 1 (a) to an assembly type lid body 5. The lid 5 is a lid piece formed by bending a plurality of substantially fan-shaped plate pieces.
5a are gathered to form a substantially bullet shape. A circular step 5b is formed at a position corresponding to the bottom of the shell, and the step 5b
b is fitted to the tip of the steel pipe 2. A round groove 5c is provided on the shell-shaped outer surface, and a steel wire 5d wound around the groove 5c holds the lid piece 5a in the shell shape.

Therefore, with respect to the ground reaction force from the lower surface, each lid piece 5a is supported by the tip of the steel pipe 2,
And because they push against each other, they maintain a roughly cannonball shape.
On the other hand, with respect to the load from the upper surface, the lid piece 5a moves to the steel pipe 2
As the steel wire 5d is separated from the tip of the steel wire, the steel wire 5d is broken into pieces. At this time, by inverting the steel pipe 2 and providing a gap (a space free of earth and sand) below the lid piece 5a, the breaking and disassembling become easier.

It should be noted that the present invention does not limit the lid to a substantially bullet shape, but may be a conical shape or an arc shape.
Slits may be processed on the outer surface thereof, or may be formed of a brittle material such as concrete. Further, instead of binding with the steel wire, it is also possible to provide concave portions or convex portions on the abutting end surfaces of the lid body pieces 5a and to lock them together.

Furthermore, the present invention is not limited to the one in which the lid is closed for the steel pipe, and when the steel pipe is penetrated into the ground,
Any part may be opened as long as it can prevent the intrusion of sediment. (Wing) FIG. 2 is a perspective view illustrating a wing in one embodiment of the screw-in type steel pipe pile according to the present invention. Figure 2 (a)
In the above, the blade 4 is constructed by welding steel plates 4a and 4b made of a fan-shaped flat plate to the outer periphery of the steel pipe 2 in the vicinity of the tip end portion by welding so as to intersect at the same height position. In addition, in FIG. 2B, a spiral blade 4c formed by cutting and bending one part of a donut-shaped steel plate is welded to the outer periphery of the steel pipe 2 in the vicinity of the tip portion, and 4 is bladed. 4 is configured. The outer diameter of the blade 4 is 1.5 that of the outer diameter of the steel pipe 2.
It is desirable to use a material having a volume ratio of about 3.0 times.

The present invention is not limited to a fan shape or an annular shape, and may be a polygonal shape or an outer peripheral elliptical shape. Alternatively, these may be formed by combining a plurality of them. Further, the mounting position is not limited to the vicinity of the tip of the steel pipe, but can be appropriately set such as a position away from the tip of the steel pipe. Moreover, you may provide in multiple steps in the axial direction as needed.

[Second Embodiment] (Construction Method) FIGS. 3, 4 and 5 are sectional views in side view for explaining an embodiment of a construction method of a screw-type steel pipe pile according to the present invention step by step. That is, the steel pipe pile 1 described in the first embodiment is constructed on the ground including the soft layer S and the support layer B. The first embodiment described in FIG.
The same parts as those are given the same reference numerals and the description thereof is partially omitted.

In FIG. 3A, the steel pipe 2 of the steel pipe pile 1
The upper end of the blade is attached to a drive motor mounted on a base machine or the like (not shown) installed on the ground and rotated to generate a propulsive force by the wood screw action of the blade 4 and penetrate into the soft layer S. To do. A drive motor may be attached to the body of the steel pipe 2 instead of the upper end of the steel pipe 2.

In FIG. 3B, when the lower end of the steel pipe 2 reaches the support layer B, the rotation is stopped.
Or, locate it near it. The rotation may be stopped before reaching the support layer B or when the support layer B is slightly penetrated.

In FIG. 3C, the bucket 10 is inserted into the steel pipe 2, and the lower excavating blade 12 or the bucket body 11 installed at the tip of the bucket body (lower side surface in the figure).
The lid 6 is broken or disassembled by pushing down. At this time, the steel pipe 2 may be reversed by a predetermined angle to provide a gap (a space free of earth and sand) below the lid 6 to facilitate the destruction or disassembly.

In FIG. 4D, the bucket 10 is rotated, the support layer B is excavated by the lower excavating blade 12, and the excavated earth and sand is stored inside the bucket body 11.

In FIG. 4 (e), while rotating the bucket 10, the side excavating blade 13 installed on the side of the bucket 11 is gradually expanded, and the side excavating blade 13 and the lower excavating blade 1 are
2 cooperate with each other to excavate the support layer B to form the expanded bottom portion 15. At this time, the excavated earth and sand is stored inside the bucket body 11. Reference numeral 16 is earth and sand stored inside the bucket body 11.

In FIG. 4 (f), the diameter of the side excavating blade 13 is reduced, the bucket 10 is collected on the ground, and the earth and sand 16 are discharged to the ground. Then, the step (e) and the step (f) are repeated until the expanded bottom portion 15 having a predetermined size (depth or the like) is formed.

In FIG. 5 (g), a tremie pipe 18 is inserted into the steel pipe 2, and concrete 17 is poured into the expanded bottom portion 15 and to a predetermined height (including the case of the entire length) of the steel pipe 2.

In FIG. 5 (h), the tremie pipe 18 is pulled up and the steel pipe 2 is rotated again, so that the blade 4 penetrates until it reaches the vicinity of the central portion of the expanded bottom portion 15. If the drive motor is removed from the steel pipe 2 in the step (c), it is installed again in the step (h).

In FIG. 5 (i), the earth and sand 16 delivered to the ground is put into the steel pipe 2. (Drum Bucket) FIG. 6 is a side view showing an embodiment of a bucket used in an embodiment of a method of constructing a screw-in steel pipe pile according to the present invention. In FIG.
The bucket 10 (so-called drum bucket) includes the rod 9,
The bucket main body 11 is fixed to the rod 9, and the lower excavating blade 12 and the side excavating blade 13 are installed on the bottom and side surfaces of the bucket main body 11, respectively.

The bucket main body 11 has a drum-shaped space for accommodating earth and sand therein. The lower excavating blade 12 excavates the earth and sand below along with the bucket body 11, and
This serves to take it into the bucket body 11. Further, the side excavating blade 13 can be laid down and erected with the rotation fulcrum 14 as a fulcrum, and is laid down to increase the diameter and erected to decrease the diameter by an operation from the ground. Furthermore, one end of the rod 9 is attached to the top surface of the bucket body 11, and the other end is gripped and rotated by, for example, a drive motor (not shown) mounted on the base machine.

[Third Embodiment] (Grab Bucket) FIG. 7 is a side view showing another embodiment of the bucket used in one embodiment of the method for constructing the screw-in type steel pipe pile according to the present invention. In FIG.
The bucket 20 (so-called grab bucket) is the rod 2
1, frame 22, slider 23, open / close arm 24,
It is composed of a shovel 25 and excavating blades 26 and 27.

The shovel 25 is composed of a pair of fan-shaped end plates each having a circular arc portion connected by a bottom plate. The shovel 25 can store earth and sand in its pocket, and the cutting blades 26, 2 are provided at the edges of the fan-shaped end plate and the bottom plate.
7 is installed. Further, the required position of the fan-shaped end plate is rotatably installed on the frame 22. Further, it is connected to the slider 23 via the opening / closing arm 24. Therefore, by operating the rod 21 from the ground, the shovel 25 opens when the slider 23 rises, while the shovel 25 closes when the slider 23 descends.

Therefore, the grab bucket 20 can be used in place of the drum bucket 10 in the second embodiment. At this time, the steps of (c) of FIG. 3 and (d) to (f) of FIG. 4 can be read as follows.

In step (c), the grab bucket 20 is inserted into the steel pipe 2 and the tip of the shovel 25 (in the figure,
The lid 6 is destroyed or disassembled by the lower surface.

In step (d), the slider 23 is lifted, the grab bucket 20 is lowered, and the excavating blade 26,
After digging 27 into the earth and sand, the slider 23 is pushed down to close the shovel 25, and the excavated earth and sand 16 is stored inside the shovel 25.

In step (e), the grab bucket 20
Is raised to the ground, the earth and sand 16 are discharged to the ground, and the support layer B is excavated in the same manner as in the step (d) to form the expanded bottom portion 15.

In step (f), the grab bucket 20
Is collected on the ground, and the earth and sand 16 are discharged to the ground. And
The step (e) and the step (f) are repeated until the expanded bottom portion 15 having a predetermined size (depth or the like) is formed.

The present invention does not limit the bucket to the drum bucket 10 or the grab bucket 19, but other excavation equipment may be used.

[0042]

EXAMPLES Next, examples according to the first embodiment will be described.

The screw-in type steel pipe pile 1 has an outer diameter of 1000 mm,
A doughnut-shaped steel plate having an outer diameter of 1800 mm, a long inner diameter of 1008 mm, a short inner diameter of 1000 mm, and a plate thickness of 40 mm was divided into two flat plates on the outer periphery of the tip portion of the steel pipe 2 having a plate thickness of 12 mm and a length of 31 m, and intersected at the same height position. And joined by welding to form the blade 4. Further, the female screw 3 was machined on the inner peripheral surface of the tip of the steel pipe 2.

The lid 6 is a circular concrete block having a thickness of 50 mm, and has a male screw 7 to be screwed into the female screw 3 on the outer circumference. In addition, a plurality of slits (width 5 mm, depth 20 mm) are radially processed on one surface, and mortar is inserted into the slits. Since the mortar is not completely integrated with the concrete block, when a tensile force acts on the slit part, the interface between the two parts separates.

The ground to be constructed is 23 m from the ground surface.
Was a soft layer having an N value of 3 up to 23 to 32 m, and a soft layer having an N value of 7 up to 23 to 32 m.

Depth 3 from the surface according to the above construction process
A bottomed portion 15 having a diameter of 5 m and a maximum outer diameter of 2000 mm was excavated. Further, the casting height of the concrete 17 by the tremie pipe 18 was 4 m from the bottom of the expanded bottom portion 15. Next, the steel pipe 2 was rotated and penetrated until the tip portion thereof reached near the center of the expanded bottom portion 15, and the blade 4 was placed inside the expanded bottom portion 15.

As described above, by installing a large diameter steel pipe pile with blades in a short time in a small amount of soil with low vibration and low noise, and by expanding the bottom and placing concrete, In combination with the existence, I was able to obtain a large tip support force. In particular, since the support layer is excavated by the drum bucket, it is not necessary to increase the size of the drive motor of the base machine that rotates the steel pipe.

[0048]

According to the screw-in type steel pipe pile and the method of constructing the same of the present invention described above, the following remarkable effects can be obtained. 1. Since a structure that installs a breakable or disassemblable lid at the tip of the screw-type steel pipe pile, it penetrates by rotating the steel pipe pile itself in the soft layer, and in the support layer, the bucket inserted into the steel pipe pile. Since it is possible to form the expanded bottom portion, it is not necessary to increase the drive motor of the rotating device that rotates the steel pipe pile itself. 2. Also, it is possible to construct a large diameter screw-type steel pipe pile with a relatively thin wall. 3. Concrete is placed in the expanded bottom part formed by the bucket, and the screw type steel pipe pile is rotated and penetrated into it, so the penetration work is easy. 4. In addition, since the blades are placed in the concrete cast on the bottom, a large amount of concrete can be used to obtain a large tip supporting force. 5. Furthermore, after the concrete is placed inside, the earth and sand excavated by the bucket is returned to the inside of the screw-type steel pipe pile, so construction can be completed with no waste soil.

[Brief description of drawings]

FIG. 1 is a perspective view of a partial cross section for explaining an embodiment of a screw-in steel pipe pile according to the present invention.

FIG. 2 is a perspective view illustrating a wing in an embodiment of a screw-type steel pipe pile according to the present invention.

FIG. 3 is a cross-sectional view in side view for explaining an embodiment of a method for constructing a screw-in steel pipe pile according to the present invention step by step.

FIG. 4 is a cross-sectional side view illustrating one embodiment of a method of constructing a screw-in steel pipe pile according to the present invention, step by step.

FIG. 5 is a cross-sectional side view illustrating one embodiment of a method for constructing a screw-in steel pipe pile according to the present invention, step by step.

FIG. 6 is a side view showing an embodiment of a bucket used in an embodiment of a method of constructing a screw-in steel pipe pile according to the present invention.

FIG. 7 is a side view showing another embodiment of the bucket used in the embodiment of the method for constructing the screw-type steel pipe pile according to the present invention.

FIG. 8 is a side view showing a conventional steel pipe pile.

FIG. 9 is a side view showing a conventional steel pipe pile.

[Explanation of symbols]

1 Screw-in steel pipe pile 2 steel pipe 3 female thread 4 It is a substantially spiral wing 4a Steel plate 4b steel plate 4c spiral wing 5 lid, 5a Lid piece 5b step 5c groove 5d steel wire 6 lid, 6a slit 7 male screw 9 rod 10 buckets 11 bucket body 12 Lower drilling blade 13 Side drilling blade 15 Bottom part 16 earth and sand 17 concrete 18 tremie tube 20 buckets 21 rod 22 frames 23 Slider 24 open / close arm 25 shovels 26 drilling blade 27 drilling blade B support layer S Soft layer B support layer

Continued front page    F-term (reference) 2D041 AA02 BA13 BA33 CA05 DB02                       FA14                 2D050 AA06 CA02 CA05 CB05 CB10

Claims (4)

[Claims] 1. A screw-in type steel pipe pile, wherein a lower end of the screw-type steel pipe pile is provided with a lid body that is broken or decomposed by a downward force. 2. In the screw-in steel pipe pile, a step of installing a lid body that is broken or decomposed by a downward force at a lower end thereof, and a step of rotating the screw-in steel pipe pile to penetrate into the ground, When it penetrates to a predetermined depth, inserting a bucket into the screw-in steel pipe pile, and breaking or disassembling the lid by pushing the lid downward, and further excavating the ground by the bucket. And a step of pulling out the bucket from the screw-in steel pipe pile, and a step of placing root-hardening concrete in the excavated area. 3. The construction of a screw-type steel pipe pile according to claim 2, wherein the screw-type steel pipe pile is further rotated and penetrated before, in parallel with or after the step of placing the concrete. Method. 4. The method for constructing a screw-type steel pipe pile according to claim 2 or 3, wherein the earth and sand excavated by the bucket is poured onto the cast concrete.