JP2015194059A - Steel pipe concrete composite pile and integrated construction method with footing part concrete - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a steel pipe concrete composite pile that can compensate for an influence on a reinforcing bar of a tensile force due to own weight of a pile body and an influence on concrete of torsion due to rotation embedding, even when clamping and constructing a concrete part to be removed, and has a sufficient integrity between a pile head joint part and a pile main body part, and can be safely applicable to either of a pre-boring construction method and an inner excavation method.SOLUTION: A steel pipe concrete composite pile comprises: a pile main body part 1 of a steel pipe concrete composite pile A where the inside of a steel pipe 2 is formed by concrete 3; a concrete pile part 5 to be removed continuing to one end of the pile main body part; a footing reinforcing steel 7 embedded in the concrete of both pile parts from the pile main body part over the concrete pile part to be removed; an axial fixing rebar for integrally fixing both pile parts; and a coating material 16 for coating the footing reinforcing steel of at least the concrete pile part to be removed among these axial rebars, and preventing the bonding with the concrete.

Description

  The present invention relates to a steel pipe concrete composite pile comprising a pile main body portion of a steel pipe concrete composite pile in which the inside of the steel pipe is formed of concrete, and a concrete pile portion to be removed that is continuous on one end side of the pile main body portion, and the composite pile. The present invention relates to an integrated construction method with footing concrete.

  When laying precast concrete piles (PHC piles / SC piles) and then connecting the piles and footings, the joints are generally designed as rigid connections, and the pushing force, pulling force, horizontal force and Must be designed to be safe against moments. In the case of prefabricated pile construction in the civil engineering field, assuming that the pile is joined to the footing so as to satisfy the structural details specified in the road bridge specifications, a reinforced concrete cross section is assumed inside the footing, and the reinforcing steel bars of the joint Check the stress level.

  In the construction, after cutting off the vicinity of the head of the pile, the concrete portion is scraped off, and the reinforcing steel bars embedded in the pile body are exposed for a predetermined length to join the pile and the footing. When the pile (upper pile) located in the head is a steel pipe concrete composite pile, it is also necessary to peel off the outer shell steel pipe of the cut-off portion.

  As described above, the cut-off work requires a lot of time and labor, and there are many problems such as wasting the steel material after cutting and scraped concrete must be disposed of.

  In view of these problems, the inventors have formed a steel pipe concrete composite pile as an upper pile and formed a steel pipe concrete composite part at one end and a concrete pile head joint at the other end. The steel pipe concrete composite part and the concrete pile head joint part are integrally formed through a plurality of reinforcing bars for connecting a footing that extend from the steel pipe concrete composite part to the pile head joint part. A pile is proposed (Patent Document 1).

  In addition, a steel pipe concrete composite pile is formed by continuously forming a concrete part to be removed (pile head joint) that is not covered with a steel pipe at one end, so that the concrete part to be removed can be easily pulled out after construction. There are proposals that can be removed (Patent Document 2, Patent Document 3, Patent Document 4). Furthermore, while the pile head joint is a steel pipe concrete composite part, the steel pipe concrete composite part and the pile head joint part are edged with a partitioning material in the tubular concrete part inside the steel pipe, and only the outer shell steel pipe is circumferentially oriented. There are proposals (Patent Document 5 and Patent Document 6) for extracting the pile head joint by simply cutting.

JP 2009-161996 A Japanese Patent Laid-Open No. 7-18675 JP 2010-196251 A JP 2011-80313 A JP 2010-255394 A JP 2013-87594 A

  Of these proposals, as a means for pulling out the pile head joints and facilitating the removal of the chip, it is performed to cover the reinforcing bars for the footing connection with pipes for preventing adhesion to concrete. Yes. Such pipe materials are generally resin pipes such as polyvinyl chloride, metal sheaths or paper pipes. As similar means, methods such as winding a tape or applying an adhesion preventing agent have been proposed.

  As described above, in extracting the pile head joint and removing the chip, it is important to cut the edge between the reinforcing steel for connecting the footing and the concrete. In this case, it is desirable that the concrete reinforcement is covered relatively firmly at the time of concrete molding to protect the reinforcing steel bar from damage, and at the time of construction, it slips out smoothly and is not attached. However, on the other hand, the pile head joint where the reinforcement reinforcement and surrounding concrete are not attached is structurally unreinforced concrete especially in the proposal that does not cover the outer shell steel pipe at the pile head joint. When construction is performed by holding and rotating the joint, there is a concern of damaging the concrete. Moreover, depending on how the reinforcing reinforcing bars are fixed, tensile force may be applied to the reinforcing reinforcing bars by the weight of the pile body.

  Moreover, in order to isolate a pile head joint part and a pile main-body part after construction, when a steel pipe is coat | covered by the pile head joint part, you have to melt | fuse or cut a boundary part. When the steel pipe is not covered at the pile head joint, a partition plate is provided at the boundary, and the reinforcing reinforcement for footing connection is fixed to the end plate of the pile head joint, etc. When gripping the pile head joint and constructing it, a tensile force is generated in the reinforcing bar for footing connection, which may cause damage.

  The pre-boring method and the medium digging method are not versatile because the pinching method used when building piles in the excavation hole is different. Furthermore, as a means of fixing the pile body part and the concrete part to be removed, there is no welding joint such as a pairing joint or triple plate joint or welding between the partition plate at the top of the pile body part and the partition plate at the bottom part of the concrete pile part to be removed. However, it is necessary to machine the end plate part (partition plate) into a special shape, and welding cannot be applied unless the pile head joint is covered with a steel pipe.

  The inventors, even when sandwiching the pile head joint (concrete to be removed if there is no steel pipe), the effect of the tensile force on the reinforcing bar due to the weight of the pile itself or the effect of twisting on the concrete due to rotary burial It is possible to provide a steel pipe-concrete composite pile with reinforced reinforcing bars in the pile that can be applied to both the pre-boring method and the inside digging method, and the integrity of the pile head joint and the pile body is sufficient. In addition, a steel pipe provided with an adhesion preventing means that prevents the above-mentioned adhesion preventing means left in the pile head joints or reinforcing reinforcing bars removed after manufacturing or construction, or that can be easily separated and removed even if they remain. A concrete composite pile is proposed.

  As means for solving the above problems, the first invention of the present application is a pile main body portion of a steel pipe concrete composite pile in which the steel pipe inner side is formed of concrete, and a concrete pile portion to be removed that is continuous to one end side of the pile main body portion. And a footing reinforcing bar embedded in the concrete of both pile parts from the pile main body part to the concrete pile part to be removed, an axial fixing bar that integrally fixes the two pile parts, and these axial reinforcing bars. Among them, a steel pipe concrete composite pile composed of a covering material that covers at least the footing reinforcing reinforcing bar of the concrete pile portion to be removed and prevents the bonding with concrete is used.

  Moreover, 2nd invention of this application is the said axial direction fixed reinforcement installed in the inside of the reinforcement member extended in the axial direction arrange | positioned on the outer peripheral side of the said removal planned concrete pile part, and the upper and lower ends are the said removal planned concrete pile. The pile head end plate of the portion and the partition plate interposed between the two pile portions are fixed respectively.

  Furthermore, a third invention of the present application is a steel pipe concrete composite pile in which the reinforcing member includes an opening that opens to an outer peripheral surface of the concrete pile to be removed.

  According to a fourth aspect of the present invention, when the covering material is molded, the reinforcing reinforcing bar is covered and softened, shrunk, or brittle or disappears by accelerated curing, and adheres to the surrounding concrete of the concrete pile portion to be removed. A steel pipe concrete composite pile characterized by comprising a covering material that can be cut.

  Further, the fifth invention of the present application is a steel pipe concrete composite pile characterized in that an engaging portion for sandwiching a pile body is formed on a pile head metal of the concrete pile portion to be removed.

  Moreover, 6th invention of this application is an integrated construction method with the footing part concrete of the steel pipe concrete composite pile of any one of Claims 1 thru | or 5, Comprising: The axial direction in the said steel pipe concrete composite pile after construction After releasing the fixation of the upper end of the fixing bar, the concrete pile part to be removed is sandwiched and lifted, and the concrete pile part to be removed is separated from the pile body part, leaving the footing reinforcement bar and the axial fixing bar. And then unfastening the lower end of the axial fixing bar, and then integrating the footing reinforcing bar with the concrete of the footing part. It was.

  In 1st invention, the steel pipe concrete composite pile which shape | molded the steel pipe inner side with the concrete is comprised from the pile main-body part and the concrete pile part to be removed continuously on the one end side of this pile main-body part, and is scheduled to be removed from the said pile main-body part. Since the plurality of footing reinforcing bars embedded in the concrete pile parts and the axial fixing bars for fixing the pile main body part and the concrete pile part to be removed integrally are arranged separately, concrete to be removed Even when the construction is carried out with the pile part sandwiched, the influence of the tensile force due to the weight of the pile body on the reinforcing bar can be avoided.

  In 2nd invention, the said axial direction fixed reinforcement is installed in the inside of the reinforcement member extended in the axial direction arrange | positioned in the outer peripheral side of the said concrete removal planned pile part, and the upper and lower ends are piles of the said concrete pile part to be removed. Since it is configured to be fixed to the head end plate and the partition plate interposed between the two pile portions, the axial fixing bars can be easily released and removed, and in some cases, unbonded prestress is added and removed. The integrity of the planned concrete pile and the pile body can be further strengthened. In addition, since the axial fixing bars are located around the outer periphery of the pile body, it is advantageous when it interferes with the placement of the footing reinforcing bars. Can be compensated by.

  In 3rd invention, since the said reinforcement member was set as the structure provided with the opening part opened to the outer peripheral surface of the said concrete removal planned pile part, the said concrete removal planned part can be pulled out after the assembly and construction at the time of manufacture. If the length of the concrete part to be removed is easy, the reinforcing member can be reused.

In 4th invention, the said covering material fulfill | performs the covering protection of the said reinforcement reinforcing bar at the time of shaping | molding, Softening shrinkage | contraction, embrittlement, or lose | disappears by accelerated curing, From the concrete of the said concrete pile part to be removed, and the covering material from which adhesion is cut In general, the covering material disappears in pile products which are subjected to normal pressure steam curing at a temperature of 60 to 90 ° C. or high temperature and high pressure curing at a temperature of about 180 ° C. and shipped after a predetermined age. Or it will be softened and weakened to keep its original shape.
As a result, the reinforcing reinforcing bars are not attached to the surrounding concrete, which is advantageous for removing the concrete piles to be removed, and it is unnecessary to discard the covering material.

  In the 5th invention, since it was set as the steel pipe concrete compound pile characterized by having formed the engaging part which grasps a pile body to the pile head metal of the above-mentioned concrete pile part to be removed, in pre-boring construction method and digging construction method Regardless, construction becomes easy. Furthermore, the engaging part which grips the pile body by a hanging hole, a protrusion, etc. can be arbitrarily provided in the pile head metal. In addition, under such a configuration, there is no problem in manufacturing under normal steel pipe concrete composite pile manufacturing conditions.

  In 6th invention, it is an integrated construction method of the steel pipe concrete composite pile and footing as described in any one of Claims 1-5, Comprising: Fixing of the axial direction fixed reinforcement of the said steel pipe concrete composite pile after construction The concrete pile part to be removed is lifted, the concrete pile part to be removed is separated from the pile main body part, and the footing reinforcing bar is integrated with the concrete of the footing part. Therefore, it is highly reliable because only the footing reinforced reinforcing bars that are not affected by the construction are applied to the stress check of the reinforced concrete section with pile head reinforcement. Note that the axial direction fixed muscle fixed muscles can be collected and reused.

It is a perspective view of the upper part of the steel pipe concrete composite pile concerning the present invention. It is a perspective view of the upper part of the state which isolate | separated the steel pipe concrete composite pile which concerns on this invention into the pile main-body part and the concrete pile part to be removed. It is a perspective view of 2nd Example of the steel pipe concrete composite pile which concerns on this invention. It is a perspective view of the upper part of the state which isolate | separated the steel pipe concrete composite pile of 2nd Example shown in FIG. 3 into the pile main-body part and the concrete pile part to be removed. It is explanatory drawing which shows the construction order of the steel pipe concrete composite pile which concerns on this invention.

  Hereinafter, the present invention will be described in detail with reference to the embodiments shown in the drawings. In FIGS. 1, 2 and 5, reference numeral 1 denotes a pile body portion constituting the steel pipe concrete composite pile A according to the present invention. The concrete 3 is formed inside the steel pipe 2 by lining or filling. 4 is a donut-shaped partition plate attached to one end of the pile body 1, and 5 is a concrete pile portion to be removed that is formed of concrete 6 continuous through the partition plate 4. A is mainly composed of the pile body part (SC part) 1 and the concrete pile part (RC part) 5 to be removed.

  Reference numeral 7 denotes a footing reinforcing bar embedded in each concrete 3 and 6 from the pile main body 1 to the concrete pile 5 to be removed, and both ends of the footing reinforcing bar 7 are reinforcing reinforcing bars formed on the partition plate 4. It is installed in each of the concrete 3 and 6 through the through-hole 8, and 9 is an axial fixing bar that fixes the pile body 1 and the concrete pile 5 to be removed together.

  As the footing reinforcing steel bar 7, reinforced concrete steel bar SD295 material, SD345 material, SD390 material, and SD490 material defined in JIS G3112 are used. These steel materials may be used as the axial fixing bar 9, but the axial fixing bar 9 may have a different reinforcing bar diameter if necessary, and may be pre-made using a PC steel bar specified in JIS G 3109. It is also possible to apply stress.

  Since the axial fixing bar 9 is not a structural material, the number and diameter necessary for fixing the concrete portion 5 to be removed to the pile main body 1 can be arbitrarily selected, collected and used repeatedly. Is also possible. However, it is preferable to arrange the axial fixing bars 9 so that the axial forces generated in the cross section are uniform so that the arrangement of the footing reinforcing bars 7 is not hindered. Moreover, when it is set as the structure which arrange | positions the said axial direction fixed reinforcement 9 to the outer periphery of the said concrete part 5 to be removed, arrangement | positioning of the said footing reinforcement reinforcement 7 is advantageous, and fixation release of the said axial direction fixed reinforcement 9 is also easy. .

  10 is a pile head hardware attached to the upper end portion of the concrete pile portion 5 to be removed, and is an end plate or a reinforcement band generally used in an existing concrete pile (PHC pile or PRC pile). In this embodiment, It consists of a pile head end plate 11 in which a pile head hardware 10 is mounted on the upper end surface of the concrete pile portion 5 to be removed, and a reinforcing band 12 wound around the pile head. In addition, 13 is an engaging member used when pinching the pile body formed by welding to the boundary part of the said pile head end plate 11 and the reinforcement band 12 in the figure.

  Similarly to the footing reinforcing bar 7, the axial fixing bar 9 is fixed by embedding one end side in the concrete 3 of the pile body 1 and the other end side is formed in the partition plate 4. It is good also as a structure which passes through the concrete 6 of the said to-be-removed concrete pile part 5 through, and is fixed to the said pile head end plate 11 by nut 15 tightening. However, in order to avoid the influence on the pile body at the time of construction, as shown in FIGS. 1 and 2, the lower end portion of the axial fixing bar 9 is connected to the female screw part formed in the fixing bar through hole 14 of the partition plate 4. Between the partition plate 4 and the pile head end plate 11 having a structure in which the bolt portion is fixed by screw connection and the upper end portion is fixed to the pile head end plate 11 of the concrete pile portion 5 to be removed by tightening a nut 15. It is desirable to fix.

  Reference numeral 16 denotes a covering material covering the footing reinforcing reinforcement 7 of the concrete pile portion 5 to be removed, and prevents the concrete pile portion 5 to be removed from the pile body portion 1 by preventing the concrete pile portion 5 from being connected to the surrounding concrete 6. It was installed to make it easier. At the same time, the covering material 16 functions to protect the surface of the footing reinforcing bar 7 during the formation of the pile body, and is performed by normal pressure steam curing at a temperature of 60 to 90 ° C or high temperature and high pressure curing at a temperature of around 180 ° C. The structure is such that softening shrinkage, embrittlement or disappearance causes the adhesion of the concrete pile portion 5 to be removed to the concrete 6 to be cut.

  Examples of the material that disappears by atmospheric steam curing at a temperature of 60 to 90 ° C. include paraffin / polyvinyl alcohol (PVA) resin. Examples of materials that soften and shrink under the same conditions include vinyl chloride and expanded polystyrene. On the other hand, as materials that disappear due to high-temperature and high-pressure curing at around 180 ° C., most of thermoplastic resins such as polyethylene, polypropylene, and acrylic have a melting point or lower, and the original shape cannot be retained. Such materials are appropriately selected depending on the curing conditions, the degree of polymerization of these materials, the density, additives, and the cost and workability depending on their form (sheet, tape, fiber).

  Generally, in pile products that are subjected to normal pressure steam curing at a temperature of 60 to 90 ° C. or high temperature and high pressure curing at a temperature of around 180 ° C. and shipped after a predetermined age, the covering material 16 made of the resin disappears or softens.・ Vulnerability will not keep the original form. As a result, the footing reinforcing bar 7 is advantageous for removing the concrete pile portion 5 to be removed from the pile body portion 1 because the adhesion to the surrounding concrete 6 in the concrete pile portion 5 to be removed is cut off. Almost no covering material 16 needs to be discarded.

  The installation example of the steel pipe concrete composite pile A having the above configuration will be described with reference to FIG. 5. The excavation hole formed by preboring the ground is filled with cement milk, and the PHC pile (φ600-10 m) is used as the lower pile on the ground. The steel pipe concrete composite pile A according to the present invention is connected to the PHC pile as an upper pile (see FIG. 5 (A)). Next, the engaging member 13 formed by welding at the boundary between the pile head end plate 11 and the reinforcing band 12 of the concrete pile portion 5 to be removed is engaged with a rotating cap (not shown) and lifted. And it rotates so that the upper end of the said concrete removal planned pile 5 may become a predetermined position, and it is embed | buried in an excavation hole.

  After the cement milk filled in the excavation hole is cured, excavation is performed around the excavation hole and the steel pipe concrete composite pile A so that the entire concrete pile portion 5 to be removed is exposed. Next, the nut 15 that has fixed the upper end of the axial fixing bar 9 to the pile head end plate 11 is loosened, and the nut 15 is removed from the upper end of the axial fixing bar 9. And by lifting the said concrete removal planned concrete pile part 5 upwards, as shown in FIG.5 (b), leaving the said footing reinforcement bar 7 and the said axial direction fixed reinforcement 9 in the said pile main-body part 1, the said removal Only the concrete 6, the pile head end plate 11 and the reinforcing band 12 of the planned concrete pile portion 5 are raised and removed.

  Next, the axial fixing bars 9 protruding upward from the partition plate 4 installed on the upper end surface of the pile body 1 are removed, and the removal method is as shown in FIG. Further, by rotating the axial fixing bar 9 counterclockwise, the fixing of the lower end portion of the axial fixing bar 9 fixed by screw connection with the fixing bar through hole 14 of the partition plate 4 is released. Thereafter, the axial fixing bars 9 are removed from the partition plate 4 and removed from the pile body 1 so that a plurality of footing reinforcements are provided from the upper end of the pile body 1 as shown in FIG. Only the rebar 7 protrudes upward.

  Therefore, a horizontal bar 17 is arranged on the footing reinforcing bar 7 standing up and exposed from the upper end of the pile main body 1, and then a footing part is formed in the footing reinforcing bar 7 and the horizontal bar 17. By placing concrete, the pile main body portion 1 and the footing portion (not shown) of the steel pipe concrete composite pile A are integrated with each other via the footing reinforcement bar 7 and the horizontal bar 17.

  3 and 4 show another embodiment of the present invention, which differs from that of the first embodiment shown in FIGS. 1 and 2 only in the structure portion of the concrete pile portion 5 to be removed. Since the other structures are the same, only the new removal scheduled concrete pile portion 25 will be described in detail below.

  3 and 4, reference numeral 25 denotes a concrete pile portion to be removed, and a plurality of reinforcing members 26 having a horseshoe-shaped cross section extending in the axial direction are installed at equal intervals in the circumferential direction of the concrete pile portion 25 to be removed. Has been. This reinforcing member 26 is installed in order to strengthen the integrity of the pile main body portion 1 and the concrete pile portion 25 to be removed, and the upper portion of the reinforcing member 26 is a top plate 27 and the lower portion is a bottom plate 28. Each is closed. In the figure, reference numerals 27A and 28A denote through-holes through which upper and lower end portions of axial fixing bars 9 described later formed in the top plate 27 and the bottom plate 28, respectively, are inserted.

  The axial fixing bar 9 is installed in a state where most of the entire length thereof is housed in the reinforcing member 26, and the upper end portion of the axial fixing bar 9 is formed on the top plate 27 of the reinforcing member 26. Through the fixed hole through hole 14 formed in the through hole 28A and the pile head end plate 11, the nut 15 is fixed to the pile head end plate 11 of the concrete pile portion 25 to be removed, which is a portion functioning as a fixing bar upper fixing portion. The lower end passes through the through hole 28A formed in the bottom plate 28, and is fixed to the female screw portion formed in the fixed muscle through hole 14 of the partition plate 4 by screw connection.

  The construction example of the steel pipe concrete composite pile A having the above configuration will be described. In the steel pipe concrete composite pile A installed in the excavation hole in the state shown in FIG. 3, the reinforcing member of the concrete pile portion 25 to be removed The nut 15 which has fixed the upper end portion of the axial fixing bar 9 accommodated in 26 to the pile head end plate 11 is loosened, and the nut 15 is removed from the upper end portion of the axial fixing bar 9.

  Then, as shown in FIG. 4, the concrete pile to be removed is left by lifting the concrete pile part 25 to be removed upward, leaving the footing reinforcing bar 7 and the axial fixing bar 9 in the pile body part 1. The concrete 6 of the part 25, the reinforcing member 25, the pile head end plate 11, and the reinforcing band 12 are raised, and the concrete pile part 25 to be removed is removed from the pile body part 1. Next, from the pile main body portion 1 left in the state shown in FIG. 4, the lower end portion of the axial fixing bar 9 is screwed off from the female screw part formed in the fixing bar through hole 14 of the partition plate 4. Pull out. As a result, only a plurality of footing reinforcing bars 7 protrude upward from the upper end of the pile body 1. Subsequent operations are the same as those described above.

A Steel pipe concrete composite pile 1 Pile body part (SC part)
2 Steel pipe 3.6 Concrete 5-25 Concrete part to be removed (RC part)
7 Reinforcing Bar Reinforcing Bar 8 Reinforcing Bar Through Hole 9 Axial Fixing Bar 11 Pile Head End Plate 12 Reinforcement Band 13 Engaging Member 14 Fixed Bar Through Hole 15 Nut 16 Covering Material 17 Horizontal Bar 18 Footing Portion 26 Reinforcing Member 27 Top Plate 28 Bottom Plate

Claims (6)

  A pile main body portion of a steel pipe concrete composite pile in which the inside of the steel pipe is formed of concrete, a concrete pile portion to be removed continuously at one end side of the pile main body portion, and both piles extending from the pile main body portion to the concrete pile portion to be removed A footing reinforcing bar embedded in the concrete of the part, an axial fixing bar for fixing both the pile parts integrally, and covering the footing reinforcing bar of the concrete pile part to be removed at least among these axial reinforcing bars. A steel pipe concrete composite pile characterized by comprising a covering material that prevents bonding with concrete.   The axial fixing bars are installed inside the reinforcing member extending in the axial direction arranged on the outer peripheral side of the concrete pile portion to be removed, and the top and bottom ends of the pile head end plate of the concrete pile portion to be removed, The steel pipe-concrete composite pile according to claim 1, wherein the pile is fixed to a partition plate interposed between both pile portions.   The steel pipe-concrete composite pile according to claim 2, wherein the reinforcing member includes an opening that opens on an outer peripheral surface of the concrete pile to be removed.   The said coating | covering material is formed by the member which softens shrinkage | contraction, becomes brittle or lose | disappears by accelerated curing of a concrete pile, and the adhesion with the concrete of the said concrete pile part to be removed cuts. Or the steel pipe concrete composite pile of 3 description.   The steel pipe concrete composite pile according to claim 1, 2, 3, or 4, wherein an engagement portion for sandwiching a pile body is formed on a pile head hardware of the concrete pile portion to be removed.   It is an integrated construction method with the footing part concrete of the steel pipe concrete composite pile of any one of Claims 1 thru | or 5, Comprising: The fixation of the upper end part of the said axial direction fixed reinforcement in the said steel pipe concrete composite pile is cancelled | released after construction Then, the concrete pile portion to be removed is sandwiched and lifted, and the concrete pile portion to be removed is separated and pulled out from the pile body portion, leaving the footing reinforcing bar and the axial fixing bar, and the axial fixing bar. After the fixing of the lower end portion of the steel tube, the footing reinforcing steel bar is integrated with the concrete of the footing portion, and the steel pipe concrete composite pile is integrated with the footing portion concrete.

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