JP2015098674A - Steel pipe pile and method of manufacturing steel pipe pile - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a steel pipe pile capable of reducing subsoil disturbance by increasing intrusion pitch.SOLUTION: The steel pipe pile includes: a pile body of a steel pipe; and plural buckets each having a shape that a steel plate is bent in an arc shape. The bucket has an arc shape in a vertical cross section relative to an axis of the pile body. Each of the buckets is attached to the pile body so that a part of the bucket protrudes from the peripheral surface and/or front end.

Description

  The present invention relates to a steel pipe pile used as a foundation pile for civil engineering structures and building structures, and a method for manufacturing the steel pipe pile.

  Conventionally, rotary press-fit steel pipe piles having rotor blades at the tip have been used as foundation piles for civil engineering structures and building structures.

  Patent Document 1 discloses a rotary press-fit steel pipe pile having a spiral rotor blade at the tip. This steel pipe pile is configured so as to be able to resist a large pulling force acting on a jacket pile during a wave or an earthquake by a bearing resistance corresponding to the projected area of the rotor blade.

  In Patent Document 1, Patent Documents 2 and 3 are referred to as rotary press-fit steel pipe piles. The steel pipe piles of Patent Documents 2 and 3 can be screwed in by applying a rotational force to a spiral rotary blade provided at the tip by a rotary press-fitting device, and can be penetrated into the water bottom ground.

JP 2000-73349 A JP-A-8-226124 JP-A-8-291518 JP 2000-54381A

(Problem 1: Suppression of ground disturbance during rotation penetration)
The penetration mechanism of the rotary press-fit steel pipe pile into the ground will be described with reference to FIG. In FIG. 1, 1 is a pile body, and 20 is a rotor blade provided at the tip of the pile body 1. When excavating by rotating the steel pipe pile with the rotational torque T, the earth and sand excavated by the rotary blade 20 is pushed upward by the rotation of the rotary blade 20. The ground reaction force F <b> 1 acting on the rotary blade 20 at that time becomes a propulsive force downward of the pile body 1. In FIG. 1, F <b> 2 indicates penetration resistance from the ground, F <b> 3 indicates horizontal force due to rotational torque, and F <b> 4 indicates frictional force acting on the rotary blade 20 from the ground around the rotary blade 20.

  FIG. 2 is a view showing an ideal penetration state of the rotary press-fit steel pipe pile. FIG. 2 shows a state where the rotary press-fit steel pipe pile makes one rotation from the left side to the right side. As shown in FIG. 2, if the penetration amount (penetration pitch) H per rotation of the rotary press-fit steel pipe pile becomes the rotary blade pitch (height of the stepped portion of the rotary blade 20) P, there is almost no ground disturbance. This is an ideal intrusion state.

  Fig. 3 is a diagram comparing the ideal penetration state (left figure) and the actual penetration state (right figure) of the rotary press-fit steel pipe pile. In each figure, the first rotary press-fit steel pipe pile and the rotation after one rotation The positions of the press-fit steel pipe piles are shown side by side.

  In an ideal penetration state, the penetration amount H per rotation of the rotary press-fit steel pipe pile is the same as the rotary blade pitch (height of the stepped portion of the rotary blade 20) P, so the leading portion of the rotary blade 20 passes through. Since the subsequent part passes through the ground position, there is almost no ground disturbance. However, in actual ground conditions, there are multiple strata (sandy soil layer, cohesive soil layer, etc.) with greatly different strength characteristics in the depth direction, and the strength (N value, qu value, etc.) within the same stratum In general, there is considerable variation.

  Therefore, in actual ground conditions, it is practically difficult to perform the penetration so that the penetration amount H per revolution becomes the rotor blade pitch P. Depending on the degree of penetration resistance, the penetration is inevitably smaller than the rotor blade pitch P. It must be pitch H.

  In particular, when the pile tip begins to penetrate a stratum boundary or a hard support layer (generally a sand layer or gravel layer with an N value of 50 or more) whose strength changes suddenly, the penetration pitch H decreases rapidly. In the first place, the confirmation of the support layer in the rotary press-fit steel pipe pile is to be grasped by the change of the management index such as the decrease in penetration and the increase in torque.

  When the penetration pitch H is smaller than the rotor blade pitch P, as shown on the right side of FIG. 3, the parallelogram diagonal line surrounded by the first (before rotation) rotary press-fit steel pipe pile and the rotary press-fit steel pipe pile after one rotation. There is a problem that the ground is disturbed in the part. As shown on the right side of FIG. 3, when the rotor blade 20 is in an idling state that continues to rotate at substantially the same depth, the earth and sand once excavated and pushed up by the rotor blade 20 are excavated again. This further promotes ground disturbance and causes a phenomenon called “slip phenomenon”. When the slip phenomenon occurs, the reaction force of the earth and sand (ground reaction force) F1 that the rotor blade 20 should obtain as a propulsion force becomes weaker with the rotation at the same depth. .

  In particular, excessive rotation of the rotor blade 20 due to a decrease in the amount of penetration in the support layer may adversely affect the expression of the tip support force and pull-out resistance force, such as a gap at the upper and lower ends of the rotor blade in the worst case. is there. This is also described in detail in Patent Document 4.

  As described above, in the rotary press-fit steel pipe pile, the penetration pitch H becomes equal to or less than the rotary blade pitch P, and the ground disturbance cannot be avoided. It is assumed that the rotary blade 20 penetrates the pile while disturbing the ground to some extent. ing. Therefore, in the conventional steel pipe pile, there exists a problem that a front-end | tip support force and a drawing-out resistance force fall by disturbance of the ground.

(Problem 2: Slow construction speed)
Generally, the rotor blade pitch (height of the step portion of the rotor blade) is about 0.25 to 0.5 Dp (Dp: pile diameter) (for example, about 15 to 30 cm at φ600 mm), but the penetration pitch becomes even smaller and harder Penetration in the intermediate layer or support layer may drop to a few centimeters.

  Furthermore, when the above-mentioned “slip phenomenon” occurs, there is a case where it is unavoidable to recover the penetration amount, and after the reverse pulling is performed while the earth and sand on the rotary blade is left behind, it may be rotated again. However, this “reverse pulling up” causes the piles that have been laid down to return to the upper side, leading to a significant reduction in construction speed. Moreover, since the blades excavate the earth and sand once pushed up above the rotor blades, there is also a problem that the supporting force is reduced.

  In addition, when the ground is soft, it is physically possible to penetrate more than the rotor blade pitch, but in order to promote ground disturbance such as a gap at the upper end of the rotor blade, It cannot be penetrated at the above construction speed.

  Crawler type pile driving machines and all-around rotating machines are used for the construction of rotary press-fit steel pipe piles, but the latter all-around rotating machine in particular has a series of operation cycles (pile chucking → rotating press fitting → chuck release). (→ chuck rise) is slow, and this is one of the reasons why the construction speed of rotary press-fit steel pipe piles does not increase.

  As described above, the rotary press-fit steel pipe pile has a penetration pitch that is equal to the rotary blade pitch at the maximum as a construction speed, and usually has a small penetration pitch equal to or less than the rotary blade pitch. There is a problem of the slow construction speed, which leads to an increase in construction cost.

(Problem 3: High manufacturing cost of rotary press-fit steel pipe piles)
Since the rotary press-fit steel pipe pile is designed to bear a large tip support force and pull-out resistance force to the rotor blades, the thickness of the rotor blades is considerably thick (generally several tens to 100 mm).

  Moreover, in the manufacture of the rotary press-fit steel pipe pile, the attachment of the rotary blade to the steel pipe tip is performed by factory welding in a separate process after the steel pipe is formed. The rotor blade itself is also pressed in a spiral shape using a circular or donut-shaped steel plate.

  Bending the thick rotor blade, which is expensive in material cost, requires a lot of installation work costs and labor, which occupies a large production cost of the rotary press-fit steel pipe pile.

  This invention is made | formed with respect to such a problem, and it aims at providing the steel pipe pile excellent in workability and workability.

In order to achieve the above object, the present invention has the following features.
[1] It has a pile body made of a steel pipe, and a plurality of buckets having a shape in which a steel plate is bent in an arc shape,
The said bucket has a circular-arc-shaped cross section in the perpendicular cross section with respect to the pile axis | shaft of the said pile body, The steel pipe pile installed so that a part of said bucket may protrude from the surrounding surface and / or front-end | tip of the said pile body.
[2] The steel pipe pile according to [1], wherein the plurality of buckets are installed with a certain angle (excluding 0 °) with respect to a pile axis direction of a pile body to be attached.
[3] The steel pipe pile according to [1] or [2], wherein the buckets have the same shape and are installed at equal intervals on a peripheral surface of the pile body.
[4] The steel pipe pile according to any one of [1] to [3], wherein the bucket is installed such that an arcuate inner circumferential surface faces the same direction with respect to a rotation direction of the steel pipe pile.
[5] A slit extending in the pile axis direction is formed in at least one of a plurality of buckets in a shape in which a tip end or a peripheral surface of a pile body made of steel pipes and a steel plate are bent in an arc shape, by the number of the buckets,
A steel pipe pile manufacturing method for manufacturing a steel pipe pile by fitting the bucket into the pile body in each of the slits.
[6] Cut one steel pipe, cut out the members to be piles and buckets,
The manufacturing method of the steel pipe pile as described in [5] which manufactures a some bucket by dividing | segmenting the circumferential direction of the member used as a bucket.

  According to the steel pipe pile which concerns on this invention, providing the steel pipe pile excellent in workability and workability by installing the bucket of the shape by which the steel plate was bent in circular arc shape in the front-end | tip or peripheral surface of a pile body. Can do.

It is a figure which shows the penetration mechanism to the ground of a rotary press-fit steel pipe pile. It is a figure which shows the ideal penetration state of a rotation press-fit steel pipe pile. It is the figure which contrasted the ideal penetration state of a rotary press-fit steel pipe pile, and an actual penetration state. It is a top view which shows the structure of the steel pipe pile which concerns on Embodiment 1 of this invention. (A) is the side view of the steel pipe pile which concerns on Embodiment 1 of this invention, and is the figure which looked at the steel pipe pile from the A direction of FIG. (B) is the perspective view which looked at the bucket from the inner side. It is a figure which shows the effect of the steel pipe pile which concerns on Embodiment 1 of this invention. It is a figure which shows the movement of the earth and sand in the steel pipe pile which concerns on Embodiment 1 of this invention. It is a figure which shows the movement of the earth and sand in the steel pipe pile which concerns on Embodiment 1 of this invention. It is a figure which shows the movement of the earth and sand in the steel pipe pile which concerns on Embodiment 1 of this invention. It is a figure which shows the total construction time of the conventional steel pipe pile and the steel pipe pile which concerns on Embodiment 1 of this invention. It is a figure which shows the front-end | tip support force and pulling-out resistance force of the steel pipe pile which concerns on Embodiment 1 of this invention. It is a figure which shows the manufacture example of the steel pipe pile which concerns on Embodiment 1 of this invention. It is a figure which shows the force which acts on the steel pipe pile which concerns on Embodiment 1 of this invention. It is a figure which shows the modifications 1-3 of the steel pipe pile which concerns on Embodiment 1 of this invention. It is a figure which shows the modification 4 of the steel pipe pile which concerns on Embodiment 1 of this invention. It is a top view which shows the structure of the steel pipe pile which concerns on Embodiment 2 of this invention. It is a top view which shows the other structure of the steel pipe pile which concerns on Embodiment 2 of this invention. It is a top view which shows other structure of the steel pipe pile which concerns on Embodiment 2 of this invention. It is a top view which shows other structure of the steel pipe pile which concerns on Embodiment 2 of this invention. It is a top view which shows the structure of the steel pipe pile which concerns on Embodiment 3 of this invention. It is a top view which shows the other structure of the steel pipe pile which concerns on Embodiment 3 of this invention. It is a figure which shows the state at the time of penetration of the steel pipe pile which has two buckets of this invention, and the steel pipe pile which has three buckets of this invention. It is a top view which shows the structure of the steel pipe pile of two buckets concerning Embodiment 4 of this invention. It is a top view which shows the other structure of the steel pipe pile of two buckets concerning Embodiment 4 of this invention. It is a top view which shows other structure of the two buckets of the steel pipe pile which concerns on Embodiment 4 of this invention. It is a top view which shows the structure of the steel pipe pile of three buckets concerning Embodiment 5 of this invention. It is a top view which shows the other structure of the steel pipe pile of three buckets concerning Embodiment 5 of this invention. It is a top view which shows the further another structure of the steel pipe pile of three buckets concerning Embodiment 5 of this invention. It is a top view which shows the structure of the steel pipe pile of four buckets concerning Embodiment 6 of this invention. It is a top view which shows the other structure of the steel pipe pile of four buckets concerning Embodiment 6 of this invention. It is a top view which shows the further another structure of the steel pipe pile of four buckets concerning Embodiment 6 of this invention.

    Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[Embodiment 1]
FIG. 4 is a view showing a vertical cross section of the steel pipe pile tip portion with respect to the pile axis according to Embodiment 1 of the present invention. Moreover, Fig.5 (a) is a side view of the steel pipe pile which concerns on Embodiment 1 of this invention, and is the figure which looked at the steel pipe pile from the A direction of FIG. FIG.5 (b) is the perspective view which looked at the bucket from the inner side. The steel pipe pile which concerns on Embodiment 1 is attached so that the some bucket 2a, 2b may protrude from the surrounding surface and front-end | tip of the pile body 1 which consists of steel pipes. Hereinafter, each component of the steel pipe pile which concerns on Embodiment 1 of this invention is demonstrated.

(Bucket shape)
In this description, the semi-cylindrical member that characterizes the structure of the steel pipe pile according to the first embodiment is referred to as a “bucket”. As shown in FIG.5 (b), the buckets 2a and 2b have the shape where the rectangular steel plate was bent by the circular arc shape. As shown to Fig.5 (a), the buckets 2a and 2b are attached to the pile body 1 so that it may have a circular-arc shaped cross section in the perpendicular cross section with respect to the pile axis | shaft of the pile body 1. As shown in FIG. A trajectory of the outer ends of the buckets 2a and 2b when the buckets 2a and 2b make one rotation about the central axis of the pile body 1 is shown as a rotation trajectory 3.

  For example, the buckets 2a and 2b can be manufactured by dividing the circumference of the steel pipe into halves with a gas or a wire saw, or can be manufactured by bending a steel plate.

  The steel pipe pile of Embodiment 1 can be manufactured as shown in FIG. Specifically, (a) In addition to the length used as the pile body 1, the extra length for this bucket 2 is estimated at the time of material arrangement, and the length obtained by adding the length of the pile body 1 and the length of the bucket 2 Prepare a steel pipe. (B) The bucket 2 portion is cut from the prepared steel pipe. (C) Half-cut the cut tubular bucket 2 to produce buckets 2a and 2b. (D) The slit 4 which attaches the buckets 2a and 2b to the pile body 1 is formed in two places. (E) The buckets 2a and 2b are attached and welded to the slit 4 of the pile body 1. (F) Thereby, a steel pipe pile can be manufactured.

  Here, the outer diameter (Dp) of the steel pipe pile, the plate thickness (tp) of the pile body 1, the bucket diameter (Db), and the bucket plate thickness (tb) may be the same (Dp = Db, tp = tb). preferable. If the pile body 1 and the bucket have the same diameter (Db = Dp), the material can be easily prepared because it can be cut out from one steel pipe as described above. However, when a considerable load is assumed on the buckets 2a and 2b, such as when the ground is hard and the penetration resistance is large, the bucket 2 is separately made of a thick material (tb> tp) corresponding to the penetration resistance. Use it.

  Further, the bucket diameter (Db) may be equal to or smaller than the outer diameter (Dp) of the pile body 1 as long as the arrangement according to the cross-sectional shape of FIG. 4 is possible.

(Slit shape)
At the tip of the steel pipe pile 1, slits 4 (two in the example of FIGS. 4 and 5) as many as the number of attached buckets 2a and 2b are formed at equal intervals in the circumferential direction. The slit 4 extends in the pile axis direction from the tip of the pile body 1. Buckets 2 a and 2 b are fitted in the slits 4 of the pile body 1, respectively. The length of the slit 4 is the attachment length of the bucket. In the example of FIG. 5, a portion obtained by subtracting the bucket mounting length 11 (the length of the slit 4) 11 from the bucket length L is a protruding length 12 where the bucket 2 protrudes from the tip of the pile body 1.

  Since the arcs of the circular pile 1 and the arcuate bucket 2 intersect with each other, the slit 4 is preferably formed obliquely in the cross section so as to follow the arc curve of the bucket 2.

(Tip shape of steel pipe pile)
Buckets 2a and 2b are inserted in the pile axis direction into the slit 4 of the pile body 1 and arranged as shown in the cross-sectional view of FIG. Each slit 4 part is joined to the pile body 1 and the bucket 2 by welding. The buckets 2a and 2b protrude from the peripheral surface and the tip of the pile body 1, respectively. The bucket 2 is installed so as to be parallel to the pile axis direction. Buckets 2 a and 2 b are installed so as to be point-symmetric with respect to the center of pile body 1. The buckets 2a and 2b are installed at the same distance from the center of the pile body 1 and at equal intervals in the rotation direction. Bucket 2a, 2b is installed so that the inner peripheral side may face the same direction with respect to the rotation direction of the steel pipe pile.

  By changing the displacement amount (a) of the bucket 2 shown in FIG. 4, the rotating bucket diameter (Dw) can be freely changed. Here, the shift amount a is the minimum interval between the buckets 2a and 2b sandwiching the center on a straight line passing through the center of the pile body 1.

(Effect of Embodiment 1 1: About suppression of ground disturbance at the time of rotation penetration)
In the steel pipe pile of the first embodiment, a plurality of buckets 2 are attached substantially parallel (longitudinal direction) to the pile axis direction. Therefore, the trajectory that the buckets 2a and 2b have passed through the ground when the steel pipe pile is rotated and penetrated together with the pushing force is like a double spiral structure as shown in FIG. 6 (in the case of two buckets). ). That is, in the steel pipe pile according to the first embodiment, when the buckets 2a and 2b pass, the ground in places other than the trajectory of the double helix is hardly disturbed.

  However, in the steel pipe pile according to the first embodiment, unlike the conventional rotary press-fit steel pipe pile, a downward ground reaction force acting on the rotor blades cannot be obtained. Does not generate large propulsion by itself. Therefore, it is necessary to rotate and penetrate the steel pipe pile while always applying a pushing force with a construction machine or the like. However, in the steel pipe pile of the first embodiment, the semi-cylindrical buckets 2a and 2b are arranged so as to extend substantially parallel to the pile axis direction, and as shown in FIG. The area S1 in contact with the ground is small and the area S2 in contact with the ground in the pushing direction is small. Therefore, in Embodiment 1, the penetration resistance applied to the steel pipe pile at the time of rotational penetration is small. For example, it is compared with the pushing force required for re-penetration when a sliding phenomenon occurs in a conventional rotary press-fit steel pipe pile. Is considered small enough.

  Thus, when the pushing force is sufficiently larger than the penetration resistance at the time of rotational penetration of the steel pipe pile according to the first embodiment and the penetration pitch is large (the helix is rough), the ground other than the helical trajectory of the bucket is Of course, since the earth and sand outside the pipe of the steel pipe pile located on the spiral trajectory passes through the bucket and is left almost as it is, the disturbance of the ground at the time of rotation penetration can be minimized.

(Effect 2 of Embodiment 1: Improvement of construction speed)
Since the steel pipe pile according to the first embodiment is not limited in the penetration pitch as in the conventional rotary press-fit steel pipe pile, the penetration pitch can be maximized as long as the pushing force continues. Thereby, the construction speed can be dramatically increased, and the construction cost can be reduced as compared with the conventional case.

  In the steel pipe pile according to the first embodiment, as the rotational penetration proceeds, when the penetration resistance gradually increases, the pushing force becomes insufficient and the penetration pitch becomes small (the spiral is dense). The main effect is to scrape the soil outside the pipe of the steel pipe pile.

  Here, when the movement of the earth and sand below the pile tip accompanying the rotation of the bucket is viewed from above the steel pipe pile, it is as shown in FIG. In this figure, the left rotation is the positive rotation. That is, the concave portions of the buckets 2 a and 2 b act to scrape the earth and sand outside the pile body 1 of the steel pipe pile and take it into the pipe of the pile body 1. In addition, the earth and sand directly under the steel pipe pile enters the pipe as it is.

  If this action continues, the soil outside the pipe scraped from each bucket will be concentrated and compressed near the rotation center of the bucket (= center of steel pipe pile), and the pipe inside will be blocked together with the pipe soil already existing at the tip of the pile. Begin to. When this blocking effect occurs in the intermediate layer before the support layer, it becomes difficult to penetrate like the slip phenomenon of the rotary press-fit steel pipe pile, which causes the construction speed to decrease.

  Moreover, as shown in FIG. 8, earth and sand outside the pipe enter between the buckets 2a and 2b and the pile body 1, the earth and sand are compressed, and the space between the buckets 2a and 2b and the pile body 1 starts to close.

  Therefore, in the first embodiment, as shown in the left diagram of FIG. 9, when a pushing force is applied while the steel pipe pile is rotated forward, the above-described blocking effect is likely to occur, as shown in the right diagram of FIG. 9. In this way, the pushing force is applied while rotating the steel pipe pile in the reverse direction. In addition, about earth and sand above a pile front-end | tip part, illustration was abbreviate | omitted. In the first embodiment, a construction machine having a margin for the pushing force is used. And when said obstruction | occlusion effect is likely to generate | occur | produce, a steel pipe pile is reversely rotated (right rotation), increasing each pushing force, and each bucket 2a, 2b is reversed. As a result, the compressed sand near the rotation center and between the buckets 2a, 2b and the pile body 1 are once loosened, and the blocked pipe soil is discharged out of the pipe to reduce the tip resistance and restore the penetration pitch. It is possible to make it.

  What should be noted here is that in the first embodiment, it is not necessary to pull up the steel pipe pile during reverse rotation. That is, in the conventional rotary press-fit steel pipe pile, when the slip phenomenon occurs, the penetration is restored by performing re-penetration after reverse rotation. On the other hand, in the steel pipe pile of the first embodiment, when the penetrability is deteriorated, as shown in the right figure of FIG. 9, if the pushing force is applied while rotating the steel pipe pile in the reverse direction, the penetration of the steel pipe pile is caused. It is possible to continue.

  FIG. 10: is a figure which shows the total construction time of the conventional steel pipe pile and the steel pipe pile which concerns on Embodiment 1 of this invention. In conventional rotary press-fit steel pipe piles, if the steel pipe piles are rotated forward and slippage occurs due to layer change slip or clogging in the pipe, the steel pipe piles are rotated in reverse each time. And raised it. Therefore, in the conventional steel pipe pile, there existed a problem that total construction time was long (left figure of FIG. 10).

  On the other hand, in Embodiment 1 of the present invention, when the steel pipe pile is rotated forward, slip phenomenon occurs due to layer change slip or soil clogging in the pipe, and when the penetration of the steel pipe pile deteriorates, the steel pipe pile is reversed. However, by applying the pushing force, the penetration can be continued without lifting the steel pipe pile. Thereby, total construction time can be shortened significantly (right figure of FIG. 10).

  As described above, in the first embodiment of the present invention, not only when the indentation force is sufficient and the penetration pitch is large, but also when the penetration pitch starts to decrease due to the blocking effect, the reverse rotation and the further application of the indentation force can be applied. Rotational penetration can be continued while maintaining high speed.

  In addition, after the front-end | tip part arrives at a support layer, in order to exhibit front-end | tip support force, it is necessary to generate | occur | produce the obstruction | occlusion effect. Therefore, it is preferable to reduce the penetration pitch only in the forward rotation in the vicinity of the support layer stopping, and to complete the construction by rotating forward at the same depth at the final stopping.

  At this time, as shown in the left diagram of FIG. 11, as the steel pipe pile is rotated in the forward direction, the blocking effect is enhanced and the tip supporting force is reliably exhibited. Moreover, as shown in the right figure of FIG. 11, since the earth and sand firmly closes also in the gap | interval of each bucket 2a, 2b and the pile body 1, and it acts as an anchor at the time of extraction, it also contributes also to the exertion of extraction resistance To do.

  In conventional rotary press-fit steel pipe piles, excessive rotation of the rotor blades in the support layer should be avoided because it may promote ground disturbance and reduce the tip support force and pull-out resistance force. Even if the steel pipe pile of Embodiment 1 of this invention rotates a steel pipe pile in the hard support layer of a ground, there is no possibility of reducing a tip support force and a drawing-out resistance force.

  By the way, if the bucket protrusion length is penetrated into the support layer by the hammering or press-fitting method at the time of final fastening, a larger tip support force can be expected.

  Moreover, although the construction of the steel pipe pile according to the first embodiment has been described on the premise of rotational penetration, it may of course be constructed by striking or press-fitting from the beginning.

(Effect 3 of Embodiment 1: About the solution of the high manufacturing cost of a rotary press-fit steel pipe pile)
In the steel pipe pile of the first embodiment, since a bucket having a shape in which a steel plate is bent in an arc shape is used, it is not necessary to prepare a thick circular steel plate that has been subjected to high-cost press processing as in the prior art. Therefore, in this Embodiment 1, the steel pipe pile which exhibits big tip support force and drawing-out resistance can be manufactured cheaply.

  As shown in FIG. 12, a steel pipe pile can be easily manufactured by preparing a surplus length in a steel pipe, cutting the surplus length portion into a bucket, and directly welding and attaching it to the steel pipe pile main body. it can.

(Effect 4 of Embodiment 1: About the safety | security of the front-end | tip part with respect to the working torque at the time of construction)
In the steel pipe pile of the first embodiment, in the forward rotation, the earth and sand outside the pipe is concentrated and compressed near the rotation center of the bucket as the bucket rotates, and loosened in the reverse rotation.

  As shown in the left diagram of FIG. 13, in the forward rotation, the ground reaction force F7 acts in the direction of spreading outward on the outer portion of the steel pipe of each bucket 2a, 2b, and the bucket 2a, 2b and the pile body The reaction force F6 which tries to go to the center of a steel pipe pile acts on the part inside pile body 1 of each bucket 2a, 2b by using 1 attachment part as a fulcrum.

  In the normal rotation, since the compressed ground exists at the rotation center (= center of the steel pipe pile), the ground reaction force F5 acts to push back the reaction force F6 of the buckets 2a and 2b toward the center of the steel pipe pile.

  In reverse rotation, on the contrary, the ground reaction force acts in the direction of entering the steel pipe outside part of each bucket 2a, 2b, and each bucket 2a, The reaction force which tries to leave | separate from the center of a steel pipe pile acts on the part inside the pile body 1 of 2b.

  As shown in the right figure of FIG. 13, in the reverse rotation, the ground compressed from the rotation center (= center of the steel pipe pile) loosens and flows out to the outside of the steel pipe. It acts to push back the reaction force F6 of the buckets 2a and 2b that are about to leave the center.

  Thus, unlike the conventional rotary press-fit steel pipe pile, the tip part of the steel pipe pile of this Embodiment 1 is a rational mechanism that is rotated and intruded while balancing the force with the help of the ground reaction force F5. You can see that Therefore, even when an excessive load is applied to the steel pipe pile, each force balances, so the steel pipe pile is not likely to be damaged and the safety during construction is high.

  In addition, when there is a possibility that the outer part of the pile body 1 of the buckets 2a and 2b may be turned up with the attachment portions of the buckets 2a and 2b and the pile body 1 as fulcrums, such as when it is necessary to rotate through the hard ground, the above-mentioned As described above, a thick bucket corresponding to the resistance is used.

  In addition, when attaching bucket 2a, 2b to the front-end | tip of the pile body 1, you may provide the slit 4 in the bucket 2 side instead of the pile body 1 side. Further, the slits 4 may be provided on both sides of the bucket 2 and the pile body 1. In this case, what is necessary is just to let the length which added the slit of the bucket 2 and the pile body 1 be the bucket attachment length l1 of Fig.5 (a).

  Next, the modification of the steel pipe pile of this Embodiment 1 is demonstrated. Fig.14 (a) is a figure which shows the modification 1 of the steel pipe pile of this Embodiment 1. FIG. As shown in the first modification, the installation location of the bucket 2 can be attached to an intermediate portion of the pile body 1. In that case, what is necessary is just to form the slit of the bucket length L extended in a pile axial direction at equal intervals in the circumferential direction of the pile body 1. FIG.

  FIG.14 (b) is a figure which shows the modification 2 of the steel pipe pile of this Embodiment 1. FIG. As shown in the modification 2, you may install the buckets 2a and 2b so that the lower end of the buckets 2a and 2b may correspond with the lower end of the pile body 1. FIG.

  FIG.14 (c) is a figure which shows the modification 3 of the steel pipe pile of this Embodiment 1. FIG. In the third modification, the buckets 2 a and 2 b protrude only from the lower end of the pile body 1. In this case, the buckets 2 a and 2 b may be joined to the lower end of the pile body 1 without forming a slit in the pile body 1.

  Moreover, as shown in the modification 4 of FIG. 15, the attachment angle of the bucket 2 is not restricted to the structure installed in parallel with a pile axial direction, When inserting in the slit of the pile body 1, it is constant angle (theta) (however, , Θ except 0 °) may be provided. As a result, it is expected that the tip support force and the pull-out resistance force are increased, and the propulsive force at the time of rotation penetration is added.

  Moreover, the shape of bucket 2a, 2b should just have an arc-shaped cross section in the cross section with respect to a pile axis | shaft. For example, the buckets 2a and 2b may have a shape having an elliptical arc in cross section.

[Embodiment 2]
A steel pipe pile according to Embodiment 2 of the present invention will be described. 16 thru | or 19 is a top view which shows the structure of the steel pipe pile which concerns on Embodiment 2 of this invention. Each of the steel pipe piles shown in FIGS. 16 to 19 has two buckets 2 a and 2 b attached to the pile body 1. The buckets 2a and 2b are semi-cylindrical and have the same shape as in the first embodiment. The buckets 2a and 2b are installed at the same distance from the center of the pile body 1 and at equal intervals in the rotation direction.

  In FIG. 16 thru | or 19, the deviation | shift amount (a) of the bucket 2, the pile diameter Dp, the bucket diameter Db, and the rotation bucket diameter Dw are changed from FIG.

  Specifically, the steel pipe pile shown in FIG. 16 is compared with the steel pipe pile of the first embodiment shown in FIG. 4 (the distance between the end of the bucket 2a and the end of the bucket 2b in the pile body 1). The deviation amount (a)) is small, and the rotating bucket diameter Dw is large. The pile diameter Dp and the bucket diameter Db are equal.

  The steel pipe pile shown in FIG. 17 has a larger displacement (a) of the bucket 2 and a smaller rotating bucket diameter Dw than the steel pipe pile of the first embodiment shown in FIG. The pile diameter Dp and the bucket diameter Db are equal.

  The steel pipe pile shown in FIG. 18 has a bucket diameter Db smaller than the pile diameter Dp. The steel pipe pile shown in FIG. 19 has a bucket diameter Db larger than the pile diameter Dp.

  As shown in FIGS. 16 to 19, the rotating bucket diameter Dw can be freely changed by arbitrarily adjusting the deviation amount a and the bucket diameter Db. It should be noted that the tip support force and the pulling resistance force that are exhibited vary depending on the rotation bucket diameter Dw.

[Embodiment 3]
A steel pipe pile according to Embodiment 3 of the present invention will be described. 20 and 21 are plan views showing a steel pipe pile according to Embodiment 3 of the present invention. The steel pipe pile shown in FIGS. 20 and 21 has three or more buckets 2 attached to the pile body 1. In the steel pipe pile shown in FIGS. 20 and 21, buckets are not in contact with each other in the pile body 1.

  Specifically, in the steel pipe pile shown in FIG. 20, three buckets 2 a, 2 b, and 2 c are attached to the pile body 1. The shape of buckets 2a, 2b, and 2c is a semi-cylindrical shape and the same shape as in the first embodiment. The three buckets 2a, 2b, and 2c are installed at the same distance from the center of the pile body 1 and at equal intervals in the rotation direction. In the example of FIG. 20, the pile diameter Dp and the bucket diameter Db are equal.

  In the steel pipe pile shown in FIG. 21, four buckets 2 a, 2 b, 2 c and 2 d are attached to the pile body 1. Except for the number of buckets 2, the other configurations are the same as those in FIG.

  In this way, any number of buckets 2 can be attached.

  FIG. 22 is a diagram showing a state at the time of penetration of a steel pipe pile having two buckets 2a, 2b of the present invention and a steel pipe pile having three buckets 2a, 2b, 2c of the present invention. As shown in the left figure of FIG. 22, in the steel pipe pile which has two buckets 2a and 2b, the inside of the two buckets 2a and 2b shown with a dot pattern is obstruct | occluded with earth and sand. On the other hand, as shown in the right figure of FIG. 22, in the steel pipe pile which has three buckets, the inside of the three buckets 2a, 2b, 2c shown with a dot pattern is obstruct | occluded with earth and sand.

  Thus, depending on the number of buckets, the movement of the earth and sand in the steel pipe pile is different, and the tip support force and the pulling resistance force to be exhibited are different.

[Embodiment 4]
A steel pipe pile according to Embodiment 4 of the present invention will be described. 23 to 25 show the steel pipe piles according to the fourth embodiment, in which buckets 2a and 2b are attached to the pile body 1 by three types of fixing methods. The two buckets 2a and 2b are semi-cylindrical and have the same shape as in the first embodiment. The two buckets 2a and 2b are installed at the same distance from the center of the pile body 1 and at equal intervals in the rotation direction. 23 to 25, buckets 2a and 2b are installed such that the inner circumferential surface of the semicircle faces the same direction with respect to the rotation direction of the steel pipe pile.

  The buckets 2 a and 2 b have one end in a cross section projecting outside from the circumferential surface of the pile body 1 and the other end accommodated in the pile body 1. The pile diameter Dp is the same as the bucket diameter Db (not shown).

  In the steel pipe pile shown in FIG. 23, one end of the cross section of the buckets 2a and 2b in the pile body 1 is disposed so as to be in contact with the inner periphery of the other bucket 2a and 2b.

  In the steel pipe pile of FIG. 24, one end of the cross section of the buckets 2 a and 2 b in the pile body 1 is in contact with the inner periphery of the pile body 1. Further, the outer peripheral surfaces of the buckets 2 a and 2 b are in contact with each other within the pile body 1.

  In the steel pipe pile of FIG. 25, a line connecting both ends in the cross section of the bucket 2 a and a line connecting both ends in the cross section of the bucket 2 b are arranged side by side on one straight line passing through the center of the pile body 1. One end in the cross section of the bucket 2 a and one end in the cross section of the bucket 2 b are in contact with each other in the pile body 1.

[Embodiment 5]
A steel pipe pile according to Embodiment 5 of the present invention will be described. FIG. 26 thru | or 28 attaches the three buckets 2a, 2b, 2c to the pile body 1 by the three types of fixing method in the steel pipe pile which concerns on Embodiment 5. FIG. All of the three buckets 2a, 2b, and 2c have the same shape of a semi-cylindrical shape. The three buckets 2a, 2b, and 2c are installed at the same distance from the center of the pile body 1 and at equal intervals in the rotation direction. Moreover, the buckets 2a, 2b, and 2c are installed so that the inner peripheral surface of a semicircle faces the same direction with respect to the rotation direction of the steel pipe pile.

  The buckets 2a, 2b, and 2c are installed at the same distance from the circle center of the pile body 1. Buckets 2 a, 2 b, 2 c are attached at equal intervals in the circumferential direction of pile body 1. The buckets 2 a, 2 b, and 2 c have one end in a cross section protruding from the peripheral surface of the pile body 1 and the other end accommodated in the pile body 1. The pile diameter Dp is the same as the bucket diameter Db (not shown).

  In the steel pipe pile of FIG. 26, in the pile body 1, one end in the cross section of the bucket 2a is in contact with the inner periphery of the bucket 2c, one end in the cross section of the bucket 2b is in contact with the inner periphery of the bucket 2a, and one end in the cross section of the bucket 2c. Is arranged so as to contact the inner periphery of the bucket 2b.

  In the steel pipe pile of FIG. 27, one end of the cross section of the buckets 2 a, 2 b, and 2 c is in contact with the inner periphery of the pile body 1 in the pile body 1. Moreover, the outer peripheral surfaces of the buckets 2a, 2b, and 2c are in contact with the outer peripheral surfaces of the other two buckets 2a, 2b, and 2c in the pile body 1.

  In the steel pipe pile of FIG. 28, one end in the cross section of the three buckets 2 a, 2 b, 2 c is arranged so as to be in contact with the center of the pile body 1.

  Thus, even in a steel pipe pile having three buckets, the buckets 2a, 2b, and 2c may be arbitrarily arranged.

[Embodiment 6]
A steel pipe pile according to Embodiment 6 of the present invention will be described. FIG. 29 thru | or 31 attaches four buckets 2a, 2b, 2c, 2d to the pile body 1 with the three types of fixing method in the steel pipe pile which concerns on Embodiment 6. FIG. All of the four buckets 2a, 2b, 2c, and 2d have the same shape of a semi-cylindrical shape. 29 to 31, the buckets 2 a, 2 b, 2 c, 2 d are installed at the same distance from the circle center of the pile body 1, and the buckets 2 a, 2 b, 2 c, 2 d are equally spaced in the circumferential direction of the pile body 1. It is attached. Buckets 2a, 2b, 2c, and 2d are installed such that the semicircular inner peripheral surface faces the same direction with respect to the rotation direction of the steel pipe pile.

  The buckets 2 a, 2 b, 2 c, and 2 d have one end in a cross section protruding outside from the peripheral surface of the pile body 1, and the other end is accommodated in the pile body 1. The pile diameter Dp is the same as the bucket diameter Db (not shown).

  In the steel pipe pile of FIG. 29, in the pile body 1, one end in the cross section of the bucket 2a is in contact with the inner periphery of the bucket 2d, one end in the cross section of the bucket 2b is in contact with the inner periphery of the bucket 2a, and one end in the cross section of the bucket 2c. Is in contact with the inner periphery of the bucket 2b, and one end of the cross section of the bucket 2d is in contact with the inner periphery of the bucket 2c.

  In the steel pipe pile of FIG. 30, one end of the cross section of the buckets 2 a, 2 b, 2 c, and 2 d is in contact with the inner periphery of the pile body 1 in the pile body 1. Moreover, the outer peripheral surfaces of the buckets 2a, 2b, 2c, and 2d are in contact with the outer peripheral surfaces of the two adjacent buckets 2a, 2b, 2c, and 2d in the pile body 1. Specifically, the outer peripheral surfaces of the adjacent buckets 2b and 2d are in contact with the outer periphery of the bucket 2a.

In the steel pipe pile of FIG. 31, one end in the cross section of the four buckets 2 a, 2 b, 2 c, 2 d is arranged so as to be in contact with the center of the pile body 1. The four buckets 2a, 2b, 2c, and 2d are arranged so as to be point-symmetric with respect to the center of the circular pipe of the pile body 1. Thus, even in a steel pipe pile having four buckets, an arbitrary bucket 2a, 2b, 2c, 2d can be attached.

DESCRIPTION OF SYMBOLS 1 Pile body 2, 2a, 2b, 2c, 2d Bucket 3 Rotating bucket diameter 4 Slit 20 Rotating blade

Claims (6)

A pile body made of a steel pipe, and a plurality of buckets in a shape in which a steel plate is bent in an arc shape,
The said bucket has a circular-arc-shaped cross section in the perpendicular cross section with respect to the pile axis | shaft of the said pile body, The steel pipe pile installed so that a part of said bucket may protrude from the surrounding surface and / or front-end | tip of the said pile body.   The steel pipe pile according to claim 1, wherein the plurality of buckets are installed with a certain angle (excluding 0 °) with respect to a pile axis direction of a pile body to be attached.   The steel pipe pile according to claim 1 or 2, wherein the bucket has the same shape and is installed at equal intervals on a peripheral surface of the pile body.   The said bucket is a steel pipe pile in any one of the Claims 1 thru | or 3 installed so that a circular arc-shaped inner peripheral surface may face the same direction with respect to the rotation direction of a steel pipe pile. At least one of a plurality of buckets in a shape in which the tip or peripheral surface of a pile body made of steel pipes and a steel plate are bent in an arc shape, slits extending in the pile axis direction are formed by the number of the buckets,
A steel pipe pile manufacturing method for manufacturing a steel pipe pile by fitting the bucket into the pile body in each of the slits. Cut one steel pipe, cut out the pile and bucket members,
The manufacturing method of the steel pipe pile of Claim 5 which manufactures a some bucket by dividing | segmenting the circumferential direction of the member used as a bucket.

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