JP5200941B2 - Screwed pile - Google Patents

Description

  The present invention relates to a screw-type pile that is embedded in the ground by the wood screw action of a wing by attaching a wing to the tip of the steel pipe or in the vicinity thereof and applying a rotational force to the steel pipe.

  Many screw-in type piles that have been buried in the ground by the wood screw action of the wing by attaching a wing to the tip of the steel pipe or in the vicinity thereof and applying rotational force to the steel pipe have been proposed so far (for example, Patent Documents). 1-3).

  First, a steel pipe pile (screw pile) described in Patent Document 1 is a steel pipe having a pair of helical wings each having a half-turn length and an outer diameter of about 1.5 to 3 times the pile body. The spiral direction is the same at the same height position on the outer peripheral surface of the lower end of the pile, and a plurality of pieces are fixed discontinuously relative to each other.

  In this structure, even on hard ground such as rake, there is no displacement of the pile core at the start of excavation and the inclination of the pile body at the time of propulsion, so that the construction accuracy is high and a stable propulsion force can be obtained. Moreover, compared with the conventional pile, the excavation blade is less worn and deformed and the amount of soil is reduced, and the rotational speed of the spiral blade is small, so that the same excavation effect can be exhibited. For this reason, the appearance of peripheral friction can also be expected, leading to an improvement in ultimate bearing capacity.

  Next, the screwed steel pipe pile with a wing described in Patent Document 2 has a steel pipe in which a tip is cut out in a substantially spiral shape and an attachment part is formed, and a radius is larger than the radius of the steel pipe and the sum of inner angles is 320 ° to 400 °. It has two or three fan-shaped flat plates formed so as to be at an angle, and these fan-shaped flat plates are joined to a mounting portion of a steel pipe so as to form a substantially spiral wing.

  In this structure, since the entire blade with the functions of both the bottom plate and the spiral blade of the steel pipe works as a support when a vertical force is applied, a large support force can be obtained. The wing constructed by arranging the wings in a substantially spiral shape provides the same screwing workability as when the wings were installed, and the wings are attached to the tip instead of the outer peripheral surface of the steel pipe. Moment is transmitted to the steel pipe and it is difficult to generate excessive bending stress.

  Next, the winged steel pipe pile (screw pile) described in Patent Document 3 includes a steel pipe, two wings, and a plate-like body extending in the axial direction of the steel pipe, and the two wings face each other with the plate-like body sandwiched therebetween. Cutting the at least part of the rear-entry part of one wing and the rear-entry part of the other wing opposite to the first-entry part of the other wing, , The first-in part of the other wing facing the rear-entry part of one wing and at least a part of the first-in part of one wing facing the rear-entry part of the other wing.

  In this structure, part or all of the rear-entry part of the other wing does not exist at the position opposite to the first-entry part of one wing. It is not necessary to increase the pressing force or the rotational force of the press-fitting machine because the ground is not hardened by being accumulated and compressed on the back surface of the rear-entry part.

JP-A-7-292666 Japanese Patent Laid-Open No. 10-102489 JP 2005-256500 A

  However, in Patent Document 1, the length of the spiral blade per sheet is [1 ÷ (number of spiral blades + 1)] or more and [1 ÷ number of spiral blades] × 1.1 or less. In the case of a wing, the number of turns is 0.33 to 0.55 per sheet, and the projected area viewed from below is in a state of lacking a circle. The larger the gap, the better the penetration in the gravel ground, but it takes time and cost to process the spiral wing. In addition, since the bending moment due to the ground reaction force is transmitted to the steel pipe because it is attached to the side surface, it is necessary to take measures such as increasing the blade thickness and increasing the steel pipe thickness and strength. Not right.

  Moreover, in patent document 2, since the sum total of the internal angle of a fan-shaped flat plate was made smaller than 360 degrees, a clearance gap was produced, and workability improved compared with a 360-degree wing, but only the step part between the wing and the wing was opened. Since the amount of soil taken up is small, the improvement in workability is not expected. It is also unclear how the wing was cut and attached.

  Further, in Patent Document 3, since the two blades are crossed and the blades are cut and not continuous, the earth and sand that exerts driving force on the upper side of the blades is separated from the blades as soon as it rotates. The sufficient driving force cannot be obtained and the workability is not improved.

  The present invention has been made in view of the circumstances as described above, and is a screw-in type pile that is embedded and embedded in the ground by applying a rotational force to the steel pipe with a wing attached to or near the tip of the steel pipe. As an object, it is intended to provide an economical screw-in pile with excellent workability.

  In order to solve the above problems, the present invention has the following features.

[1] A substantially spiral wing formed by a plurality of fan-shaped flat plates having a total inner angle of approximately 360 ° at or near the tip of the steel pipe ,
The spiral wing is
In the shape of projecting the spiral wing on the ground, a first notch cut out so as to have a gap between the spiral lower end and the spiral upper end,
A second cutout portion in which the outer peripheral side of the inclined lower end portion of the lower wing that is a fan-shaped flat plate that first penetrates the ground is cut out;
The screw-type pile characterized by the opening part formed in the center of the said helical wing | blade being provided.

[2] The second cut-out portion is screwed according to the apex angle of the helical lower end is characterized in that it is a cutout portion formed by cutting out the following sector-shaped 90 ° [1] Formula pile.

[3] The screwed pile according to [1] or [2] , wherein the spiral wing is formed by two fan-shaped flat plates.

  In the screwed pile according to the present invention, since the notched portion formed by cutting out the spiral lower end portion or the spiral upper end portion of the substantially spiral wing is provided, the cutting surface to the ground becomes large, and the penetration property is improved. Since the opening is provided near the center of the spiral wing, it is possible to promote soil uptake. In addition, since it is not necessary to bend a blade such as a spiral blade, the cost can be reduced.

1 is a perspective view showing a first embodiment of the present invention. It is a longitudinal cross-sectional view which shows the 1st Embodiment of this invention. It is a longitudinal cross-sectional view which shows the 1st Embodiment of this invention. It is a top view which shows the 1st Embodiment of this invention. It is a figure which shows the state of the wing | tip end which penetrates into the ground. It is the figure which compared the effect | action of the wing | blade at the time of penetrating into the ground. It is a figure which shows the front-end | tip part of the steel pipe in the 1st Embodiment of this invention. It is a figure which shows attachment of a reinforcement board. It is a figure which shows attachment of a stiffener. It is a perspective view which shows another aspect (Example which integrally formed the attachment part of a wing | blade and a steel pipe by casting molding) of the 1st Embodiment of this invention. It is a perspective view which shows the 2nd Embodiment of this invention. It is a longitudinal cross-sectional view which shows the 2nd Embodiment of this invention. It is a top view which shows the 3rd Embodiment of this invention. It is a top view which shows the 4th Embodiment of this invention. It is a top view which shows the 5th Embodiment of this invention. It is a figure for demonstrating the effect of the 5th Embodiment of this invention. It is a top view which shows the 6th Embodiment of this invention. It is a top view which shows the 7th Embodiment of this invention. It is a top view which shows the 8th Embodiment of this invention.

    Embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
The screwed-type pile which concerns on the 1st Embodiment of this invention is shown in FIGS. 1 is a perspective view of a screwed pile according to the first embodiment, FIG. 2 is a longitudinal sectional view as seen in the direction of arrow X in FIG. 1, FIG. 3 is a longitudinal sectional view as seen in the direction of arrow Y in FIG. FIG. 4 is a plan view.

  As shown in FIGS. 1 to 4, the screw-type pile 1 </ b> A according to the first embodiment has two fan-shaped flat plates (steel plates) 11 a having a total inner angle of 360 ° at the tip of the steel pipe 2, A substantially spiral wing 10 formed by 11b is attached, and is a screw-in type pile embedded in the ground by applying a rotational force to the steel pipe 2. Here, the fan-shaped flat plate 11a that first penetrates into the ground is referred to as the lower wing 11a, and the other fan-shaped flat plate 11b is referred to as the upper wing 11b. Incidentally, in the substantially spiral wing 10, as shown in FIG. 2, the connecting position 11s between the lower wing 11a and the upper wing 11b is outside the steel pipe 2, and the inclination angle γa of the lower wing 11a and the upper wing 11b The inclination angle γb is substantially equal (γa≈γb).

  In addition, as shown in FIG. 4, the screwed pile 1A according to this embodiment has a spiral lower end portion (an inclined lower end of the lower wing 11a) that is initially adjacent to the shape of the spiral wing 10 projected onto the ground. Section) and the upper end of the spiral (inclined upper end of the upper wing 11b), a fan having an apex angle (center angle) α with the lower end of the spiral (inclined lower end of the lower wing 11a) as the apex of the steel pipe center O. A cutout portion 21 cut out in a shape is provided, and an opening 30 cut out in the vicinity of the center of the spiral wing 10 is provided as shown in FIGS.

  In FIG. 4, the angle in the direction in which the spiral rises (counterclockwise in FIG. 4) starts from the lower end of the spiral (the initial lower end of the lower wing 11a) before the notch 21 is provided. θ represents the angular position of the spiral wing 10. That is, the position of the angle θ = 0 ° is the initial start point of the spiral (the initial lower slope of the lower wing 11a), and the angle θ = α is the start point of the spiral after the notch (the lower wing 11a after the notch). Inclined lower end), the position of the angle θ = 180 ° is the middle position of the spiral (the connection position between the lower wing 11a and the upper wing 11b), the position of the angle θ = 360 ° is the end point of the spiral (the inclined upper end of the upper wing 11b) ) Therefore, here, the range of the angle θ = 0 ° to 45 ° is notched, and the fan-shaped notch 21 having the apex angle α = 45 ° is formed.

  The notch angle α of the notch 21 will be described below based on FIG. Here, FIG. 5 shows the relationship between the lower wing 11a and the earth and sand 9 at the lower end of the spiral (the lower end of the lower wing 11a) after the notch 21 is provided.

  When the notch angle α = 0 ° shown in FIG. 5 (a) (that is, when the notch portion 21 is not present), the new ground hits the tip of the lower wing 11a in the radial direction and hits the ground at a point. Therefore, excavation force is small. In the ground which is not so hard, the penetration range is reduced, so the penetration is not good. In addition, since the lower wing 11a is inclined so that the earth and sand 9 on which it has been ridden away from the steel pipe 2, the vertical component force contributing to the propulsive force is reduced.

  In the case of the notch angle α = 45 ° shown in FIG. 5 (b), the lower wing 11a is close to a right angle with respect to the steel pipe 2 as compared with FIG. 5 (a), and the radial surface of the lower wing 11a is It becomes close to the state of hitting the ground. In addition, the movement of the earth and sand 9 on the lower wing 11a is also smaller than α = 0 ° in FIG. 5A, and the weight of the earth and sand 9 contributes to the propulsive force.

  In the case of the notch angle α = 90 ° shown in FIG. 5 (c), the lower wing is attached to the steel pipe 2 at a right angle and penetrates into the ground at the surface, like the spiral wing produced by bending. The earth and sand 9 rides on 11a, and it is easy to obtain a driving force. That is, since the earth and sand 9 on the lower wing 11a does not leave the wing 10, the weight of the earth and sand 9 contributes sufficiently to the propulsive force. The state in which the earth and sand 9 are always on the wing 10 is the easiest to obtain the propulsive force, so that the penetration of this structure is good in the ground that is not so hard.

  In the case of the notch angle α = 135 ° shown in FIG. 5D or the notch angle α = 180 ° shown in FIG. 5E, the radial inclination of the lower wing 11a is shown in FIG. This is opposite to the case of the notch angle α = 45 ° and the case of the notch angle α = 0 ° of FIG. 5A, so that the earth and sand 9 behaves closer to the steel pipe 2 and contributes to the propulsive force.

  However, if the notch angle α is large, more earth and sand 9 can be taken into the steel pipe 2, so that the penetration is improved. However, for the vertical support force that is a necessary function as a pile, the blade 10 Since the projected area of the above becomes small, the vertical supporting force may be reduced.

  Therefore, when the inventors investigated the vertical support force by changing the notch angle by analysis, the support force when the notch portion 21 is not present (that is, when the notch angle α = 0 °) is 100%. Then, it was about 95% when the notch angle α = 45 °, and about 88% when the notch angle α = 90 °. The bearing capacity value may vary depending on the hardness of the ground and the construction situation, but qualitatively, the analysis shows. In consideration of workability and supporting force, the notch angle α is preferably in the range of about 10 ° to 45 °. Even when the notch angle α is close to 90 °, it is possible to substantially increase the projected area of the blade 10 and increase the supporting force by attaching a drilling blade or the like.

  In the screwed pile 1A according to this embodiment, the upper wing 11b is continuously attached from the position of the angle θ = 180 ° with the substantially same inclination angle γb as the inclination angle γa of the lower wing 11a. In the range of the angular position θ = 180 ° to 360 ° of the upper wing 11b, the inclination of the radial wing is the same as the range of the angular position θ = 0 ° to 90 ° of the lower wing 11a. Thus, there is no problem in penetration even if the inclination in the radial direction is the same.

  As a result, as shown in FIG. 6A, in the screwed pile 1A according to this embodiment, since the substantially spiral wing 10 is attached, the trajectory of the earth and sand 9 passes through the upper surface of the wing 10 and the propulsive force The mechanism contributes to the above, and exhibits the same behavior as that of the spiral blade 80 as shown in FIG. From this, the screwed pile 1A according to this embodiment can obtain substantially the same propulsive force as the spiral blade 80. On the other hand, as shown in FIG. 6C, in the case of the wing 90 in which the fan-shaped flat plates 91a and 91b are attached so as to intersect at the steel pipe center, the wing 90 is discontinuous and the earth and sand 9 is above the wing 90. The driving range is reduced, so that sufficient driving force cannot be obtained.

  Further, as described above, a substantially circular opening 30 is provided at the center of the wing 10, thereby facilitating uptake of the earth and sand 9 into the steel pipe 2. The diameter of the opening 30 is about 0.25 to 0.9 times the outer diameter D of the steel pipe 2, but if the opening is opened 0.4 times or more of the outer diameter D of the steel pipe 2, the effect of taking up soil by the opening is obtained. growing. However, if the opening 30 is enlarged, the workability is improved, but the supporting force is lowered, so it is preferable to determine the shape by balancing both. Further, if the diameter of the blade 10 is increased and the overhang from the steel pipe 2 is increased, the balance of the bending moment caused by the ground reaction force at the time of service is also deteriorated. Therefore, it is desirable to reduce the opening 30 when the overhang is large. .

  In addition, as shown in FIG. 7, it forms in the front-end | tip part of the steel pipe 2 by dividing into 2 via the 1st level | step-difference part 4a and the 2nd level | step-difference part 4b in the circumferential direction, and it is the same direction at the substantially same angle. The 1st attaching part 3a (the front-end | tip part side of the steel pipe 2) which consists of an inclined surface which faces is provided, and the 2nd attaching part 3b is provided. Note that the first mounting portion 3a and the second mounting portion 3b are discontinuous but have a substantially spiral shape. And height h1 of the 1st level | step-difference part 4a used as the level | step difference between the lower end part of the lower wing | blade 11a and the upper end part of the upper wing | blade 11b depends on the state of the ground which penetrates the pile 1A, the outer diameter of the steel pipe 2, etc. In general, h1 = 0.1 to 0.5D (D is the diameter of the steel pipe 2) is generally desirable, and the second step is a step between the upper end of the lower wing 11a and the lower end of the upper wing 11b. The height h2 of the stepped portion 4b is formed slightly higher than the thickness of the fan-shaped flat plates 11a and 11b constituting the wing 10. When the height h1 of the first step portion 4a is less than 0.1D, the penetration amount of the pile 1A per revolution is remarkably reduced, and when it exceeds 0.5D, the penetration amount per revolution is increased. Therefore, the torque for rotating the pile 1A becomes excessive.

  The blade 10 is formed by using flat plates 11a and 11b obtained by dividing a circular steel plate or an elliptical steel plate having an outer diameter larger than the outer diameter D of the steel pipe 2 from the center, and the diameter of the blade 10 is as follows. Depending on the condition of the ground through which the pile 1A penetrates and the outer diameter of the steel pipe 2, etc., considering the balance between the screwing workability and the size of the supporting force, about 1.2 to 3 times the outer diameter D of the steel pipe 2 Is desirable.

  The upper end portion (end portion) of the lower wing 11a and the lower end portion (start end portion) of the upper wing 11b are joined by welding, but as shown in FIG. By attaching the (plate) 41, the same strength as that of one wing can be obtained. Moreover, you may attach a reinforcement board (blocking board) to the 1st level | step-difference part 4a similarly by the plate | board thickness of the wing | blade 10. FIG.

  Further, as shown in FIGS. 9A and 9B, the first stepped portion 4a is provided with a stiffener 42 for reinforcing the steel pipe 2 on the inner side or the outer side of the steel pipe 2, thereby increasing the size. A structure that can withstand torque can also be made possible.

  Thus, in the screwed pile 1A according to this embodiment, the notched portion 21 is formed by notching the spiral lower end portion (spiral start portion) of the substantially spiral wing 10; The cut surface can be increased, the penetrability can be made substantially the same as that of the spiral wing, and the opening 30 is provided near the center of the spiral wing 10, so that the uptake of soil can be promoted. And since the bending process of a wing | blade like a spiral wing | blade is unnecessary, cost reduction is attained. Therefore, the screwed pile 1A according to this embodiment is an economical screwed pile while having excellent workability.

  In addition, although the diameter D of the steel pipe 2 used for the screwed-type pile 1A which concerns on this embodiment is about 100-2000 mm, the case where a large diameter steel pipe whose diameter D is about 800-2000 mm is used is especially large.

  Further, in this embodiment, the blade 10 is formed using flat plates 11a and 11b obtained by dividing a circular steel plate or an elliptical steel plate having an outer diameter larger than the outer diameter D of the steel pipe 2 into two from the center. It is also possible to produce the same, and an equivalent effect can be obtained.

  That is, as shown in FIG. 10, the attachment part 2a of the wing | blade 10 and the steel pipe 2 can be integrally manufactured by casting. When mass-producing the same shape, the cost can be reduced, and the effect is particularly large at a small diameter. The length of the attachment portion 2a is about 10 cm to 200 cm, and can be appropriately changed depending on the steel pipe diameter and the production status. Connection to the steel pipe 2 (steel pipe main body) is performed by a mechanical joint using welding or bolts. Since there is no change in the wing shape, it is possible to obtain the same workability and supporting force characteristics as those of the wing formed using flat plates 11a and 11b obtained by dividing a circular steel plate or an elliptical steel plate into two from the center.

(Second Embodiment)
The basic structure of the screw-type pile according to the second embodiment of the present invention is the same as that of the screw-type pile 1A according to the first embodiment, but is a perspective view in FIG. 11 and a longitudinal section in FIG. As shown in the plan view (longitudinal sectional view corresponding to FIG. 2), in the screwed pile 1B according to the second embodiment, the connecting position 11s between the lower wing 11a and the upper wing 11b is the lower end position of the steel pipe 2. It has become. Regarding the inclination angle of the wing, the inclination angle γa of the lower wing 11a and the inclination angle γb of the upper wing 11b are substantially equal (γa), as in the screwed pile 1A according to the first embodiment. ≈γb (not shown in FIG. 12).

  The thickness of the wing | blade 10 is decided according to a pile diameter, a wing | blade diameter, support force, etc., and plate | board thickness thicker than a pile body is used normally. In this embodiment, since the connecting position 11s between the lower wing 11a and the upper wing 11b is the lower end position of the steel pipe 2, the wings can be joined by welding. If there is a case where a gap is generated, it may be welded with a closing plate. In the case of the second embodiment, the same effect as in the case of the first embodiment can be obtained.

(Third embodiment)
The screw-type pile according to the third embodiment of the present invention has the same basic configuration as the screw-type pile 1A according to the first embodiment, but as shown in a plan view in FIG. In the screwed pile 1C according to the third embodiment, with respect to the shape of the spiral wing 10 projected onto the ground, the spiral lower end (the inclined lower end of the lower wing 11a) and the spiral upper end ( A notch 21 is provided between the upper end of the upper wing 11b and the upper end of the spiral (the upper end of the upper wing 11b) in a fan shape having an apex angle α with the steel pipe center O as the apex. It has been. That is, here, the range of the angle θ = 315 ° to 360 ° is notched, and the fan-shaped notch 21 having the apex angle α = 45 ° is formed.

  Since 1 C of screwed-type piles which concern on this embodiment are not notched in the spiral lower end part side (spiral start end part side), penetrability falls. However, if the ground to be penetrated is very hard gravel or rock, it is difficult to perform the construction according to the pitch of the wing. It becomes impossible or the wing breaks down. Therefore, the construction is carried out while suppressing the increase in torque while cutting the ground, and the wing of this screw-type pile 1C that hits at a point is more suitable than the spiral wing that hits the excavation position on the surface. Regarding the bearing capacity characteristics, it is the same as the screw-type pile 1A. The connection position 11s between the lower wing 11a and the upper wing 11b may be set as the lower end position of the steel pipe 2 as in the screwed pile 1B according to the second embodiment.

(Fourth embodiment)
The basic structure of the screwed pile according to the fourth embodiment of the present invention is the same as that of the screwed pile 1A according to the first embodiment, but as shown in a plan view in FIG. In the screwed pile 1D according to the fourth embodiment, with respect to the shape of the spiral wing 10 projected onto the ground, the spiral lower end (the inclined lower end of the lower wing 11a) and the spiral upper end ( Between the upper end of the upper wing 11b), the lower end of the spiral (the lower end of the lower wing 11a) is cut out into a fan shape having an apex angle α1 with the steel pipe center O as the apex, and the upper end of the spiral ( A notch 21 having an apex angle α (α = α1 + α2) is formed by cutting out the upper end of the upper blade 11b into a fan shape having an apex angle α2 with the steel pipe center O as the apex. That is, here, the range of the angle θ = 0 ° to 22.5 ° and the range of the angle θ = 337.5 ° to 360 ° are notched, and the fan-shaped notch 21 having the apex angle α = 45 °. Is formed.

  In the screw-type pile 1D according to the fourth embodiment, intermediate workability between the screw-type pile 1A according to the first embodiment and the screw-type pile 1C according to the third embodiment is obtained. It is desirable to use properly according to the situation. Also in this embodiment, it is good also considering the connection position 11s of the lower wing | blade 11a and the upper wing | blade 11b as the lower end position of the steel pipe 2 like the screwed-type pile 1B which concerns on 2nd Embodiment.

(Fifth embodiment)
The basic structure of the screwed pile according to the fifth embodiment of the present invention is the same as that of the screwed pile 1A according to the first embodiment, but a plan view is shown in FIG. Thus, in the screwed pile 1E according to the fifth embodiment, as the notch portion 21, in addition to the first notch portion 21a of the apex angle α, the spiral lower end side (the inclination of the lower wing 11a) A second notch portion 21b having an apex angle β1 formed by further notching the outer portion of the steel pipe 2 on the lower end side) is provided. In addition, in the screwed pile 1F according to the fifth embodiment, as shown in a plan view in FIG. 15 (b), as the notch portion 21, in addition to the first notch portion 21a of the apex angle α. The second notch portion 21b of the apex angle β1 and the second step of the apex angle β2 formed by notching the inner portion of the steel pipe 2 on the spiral upper end side (inclined upper end side of the upper blade 11b). An eye notch 21c is provided.

  Thus, in addition to the first notch portion 21a having the apex angle α, the second notch portion 21b having the apex angle β1 is provided, so that the spiral lower end portion (the lower wing 11a of the lower wing 11a) is triggered. Since the shape of the lower end portion is close to parallel to the ground as shown in FIG. 16 (b) as compared to the case of the screwed pile 1A shown in FIG. 16 (a), it becomes easier to obtain a propulsive force. .

  It is desirable that the apex angle α is in the range of 0 ° to 45 °, the apex angle β1 is in the range of 0 ° to 45 °, and the apex angle β2 is in the range of 0 ° to 45 ° (however, all of α, β1, and β2) Except for 0 °). The second notch portion 21c of the apex angle β2 is preferably provided when it is desirable to widen the opening and take in a large amount of gravel into the pipe with respect to the gravel ground. In the sand ground or the like, as shown in FIG. 15A, it is not necessary to provide the second notch portion 21c having the apex angle β2.

  Of course, the threaded pile 1B according to the second embodiment, the threaded pile 1C according to the third embodiment, and the threaded pile 1D according to the fourth embodiment are similarly cut out at the second stage. Can be provided.

(Sixth embodiment)
The basic structure of the screwed pile according to the sixth embodiment of the present invention is the same as that of the screwed pile 1A according to the first embodiment, but as shown in a plan view in FIG. In the screwed pile 1G according to the sixth embodiment, with respect to the shape obtained by projecting the spiral wing 10 onto the ground, the spiral lower end (the inclined lower end of the lower wing 11a) and the spiral upper end ( Between the upper end of the upper wing 11b, the lower end of the spiral (the lower end of the lower wing 11a) is cut out with a space e substantially parallel to the upper end of the spiral, and the lower end of the spiral (lower wing). 11a is provided with a notch 21 formed by notching the outer portion of the steel pipe 2 on the inclined lower end portion side of 11a into a fan shape with apex angle β1 with the vicinity of the intersection of the outer periphery of the steel pipe 2 and the spiral lower end as a vertex. Yes.

  The interval e is preferably about ¼ or less of the outer diameter D of the steel pipe 2 and the apex angle β1 is preferably 60 ° or less. In this embodiment, the opening is widened so that a large amount of earth and sand can be taken into the pipe, and the blades on the outside of the steel pipe 2 are notched, so that a propulsive force can be easily obtained. Also in this embodiment, it is good also considering the connection position 11s of the lower wing | blade 11a and the upper wing | blade 11b as the lower end position of the steel pipe 2 like the screwed-type pile 1B which concerns on 2nd Embodiment.

(Seventh embodiment)
The screw-type pile according to the seventh embodiment of the present invention has the same basic configuration as the screw-type pile 1A according to the first embodiment, but as shown in a plan view in FIG. In the screwed pile 1H according to the seventh embodiment, with respect to the shape of the spiral wing 10 projected onto the ground, the spiral lower end (the inclined lower end of the lower wing 11a) and the spiral upper end ( Between the upper end of the upper wing 11b and the lower end of the spiral (the lower end of the lower wing 11a), the vicinity of the end on the outer periphery of the opening 30 (the inner periphery of the spiral wing) is the apex. A cutout portion 21 formed by cutting out into a fan shape having an apex angle β1 is provided.

  The apex angle β1 is desirably 90 ° or less, and more preferably 60 ° or less. Also in this embodiment, the opening is widened so that a large amount of earth and sand can be taken into the pipe, and the wings on the outer side of the steel pipe 2 are notched, so that a propulsive force can be easily obtained. Also in this embodiment, it is good also considering the connection position 11s of the lower wing | blade 11a and the upper wing | blade 11b as the lower end position of the steel pipe 2 like the screwed-type pile 1B which concerns on 2nd Embodiment.

(Eighth embodiment)
The basic configuration of the screwed pile according to the eighth embodiment of the present invention is the same as the screwed pile 1A according to the first embodiment, but as shown in a plan view in FIG. In the screwed pile 1I according to the eighth embodiment, the spiral wing 10 is composed of three pieces of a lower flat plate (lower wing) 12a, an intermediate flat plate (intermediate wing) 12c, and an upper flat plate (upper wing) 12b. It is formed with a fan-shaped flat plate. In some cases, it may be formed of four or more fan-shaped flat plates.

  Thus, handling at the time of manufacture becomes easy by increasing the number of fan-shaped flat plates.

  Of course, in the screwed pile 1C according to the third embodiment, the number of fan-shaped flat plates can be similarly increased.

  As an example of the present invention, the threaded pile 1E according to the fifth embodiment (see FIG. 15A) was used for construction.

  Here, the diameter of the steel pipe 2 is φ1200 mm, the thickness of the steel pipe 2 is 19 mm, the diameter of the blade 10 is 1800 mm, the thickness of the blade 10 is 70 mm, and the notch of the blade 10 is the first notch angle α Was 22.5 °, the second notch angle β1 was 30 °, and the size of the opening 30 was 0.5 times the steel pipe diameter D.

  The ground was composed of a gravel layer having an N value of 50 or more in the support layer, a hard sand layer having an N value of 25 to 35, and a clay / silt layer having an N value of about 5 to 15 in an intermediate layer.

  Then, when the threaded pile 1E was constructed to a rooting length of 49 m with an all-around rotating machine, the torque was about 2500 kN · m at the maximum, not a very large value, and could be constructed smoothly up to the support layer.

  From the above, the effectiveness of the screw-in type pile according to the present invention could be confirmed.

DESCRIPTION OF SYMBOLS 1A Screw-in type pile 1B Screw-in type pile 1C Screw-in type pile 1D Screw-in type pile 1E Screw-in type pile 1F Screw-in type pile 1G Screw-in type pile 1H Screw-in type pile 1I Screw-in type pile 2 Steel pipe 2a Steel pipe and wing attachment part 3a 1st Attachment portion 3b Second attachment portion 4a First step portion 4b Second step portion 9 Earth and sand 10 Wings 11a Lower wing 11b Upper wing 11s Connection position of lower wing and upper wing 12a Lower wing 12b Upper wing 12c Intermediate wing 20 Step Part 21 Notch part 21a First stage notch part 21b Second stage notch part 21c Second stage notch part 30 Opening part 41 Reinforcement plate 42 Stiffener 80 Spiral wing 90 Crossed wings 91a, 91b Fan shape Flat plate

Claims (3)

A substantially spiral wing formed by a plurality of fan-shaped flat plates having a total inner angle of approximately 360 ° at or near the tip of the steel pipe,
The spiral wing is
A lower wing that is a fan-shaped flat plate that first penetrates the ground;
A first cut-out portion the outer peripheral side of the inclined lower end portion of the lower blade which all Ri off,
In a shape projected on the ground, a second notch cut out so as to have a gap between the spiral lower end and the spiral upper end;
And an opening formed in the center of the spiral wing. The second cut-out portion, screwed pile according to claim 1, wherein the apex angle of the helical lower end is a cut-away portion formed by cutting out the following fan-shaped 90 °. The screwed pile according to claim 1 or 2, wherein the spiral wing is formed by two fan-shaped flat plates.

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