JP2009299374A - Concrete pile with shell steel pipe and manufacturing method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a concrete pile with a shell steel pipe applicable also to a pile head reinforcement with a long overall length, by installing a cylindrical pile reinforcement, buried in a hollow concrete body on the inner surface of a steel pipe easily at predetermined positions, regardless of the size of the steel pipe, and to provide a concrete pile with a shell steel pipe provided by the method. <P>SOLUTION: In this concrete pile 1 with a shell steel pipe, the cylindrical concrete body 3 is integrally formed with the inner surface of the shell steel pipe 2, and the pile head reinforcements 5, formed by cylindrically assembling a plurality of main reinforcements 5a and hoop reinforcements 5b are buried in the shell steel pipe. A support member 6, formed of the reinforcements bent in a ring having a diameter larger than the inside diameter of the shell steel pipe 2 and elastically deformable in the diameter-reducing direction are jointed to the other ends of the pile head reinforcements 5 via a means for binding to the plurality of main reinforcements 5a. The pile head reinforcements 5 are locked, at concentric positions at predetermined intervals from the inner surface of the shell steel pipe 2, by being resiliently brought into contact with the inner peripheral surface of the shell steel pipe 2. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a concrete pile with an outer shell steel pipe formed by integrating a steel pipe on the outer periphery of a hollow concrete pile body and a method for manufacturing the same.

  Conventionally, a concrete pile with an outer shell steel pipe (also referred to as an SC pile) having a configuration in which a cylindrical concrete body is provided in close contact with an inner surface of a steel pipe by centrifugal molding using a type of foundation pile as a kind of foundation pile. Are known. In the construction of such a foundation pile, a pile head reinforcing bar for reinforcement and integration with the foundation concrete is joined to the pile head. Pile head reinforcement is also called a cage rebar (reinforcing bar, intermediate filling reinforcement, etc.) in which a plurality of main bars used in the pile head joint structure of pre-stressed concrete piles are assembled in a cylindrical shape with hoop bars. ), And integration with the pile body is achieved by filling the concrete with the lower end side portion inserted into the hollow portion inside the concrete body.

  By the way, when the inner diameter of the pile body is small in the above method, the required number of main bars may not be arranged, and in such a case, the lower end of the reinforcing bar is directly welded to the steel pipe outer peripheral surface of the pile head, Alternatively, a method of screwing a threaded joint reinforcing bar or a deformed reinforcing bar threaded at an end through a coupler welded to the outer peripheral surface of the pile head is performed. However, when welding pile head reinforcement bars or couplers for standing the pile heads of concrete piles with shell steel pipes embedded in the ground, the working environment is limited. In addition, it is difficult to shorten the work time because it is a troublesome welding work along each pile head reinforcement bar or coupler, and it is also susceptible to the weather, and the welding quality tends to become unstable. And there were not a few quality control problems. On the other hand, when welding work is performed in advance in a place other than the site such as a factory, pile head reinforcement bars and couplers welded to the end of the concrete pile with the outer shell steel pipe are inserted when the concrete pile with the outer shell steel pipe is driven. It tends to interfere with the driving work and lead to a decrease in workability. Furthermore, when the concrete pile with outer shell steel pipe hits hard ground or rocks during driving and it becomes difficult to drive further (high stop), the protruding length from the ground surface will be the predetermined length In some cases, after the excess portion was removed, there was a case where the pile head reinforcing bars and couplers had to be re-welded to the pile head.

Based on such a situation, a plurality of reinforcing bars of a predetermined length having at least a fixing length for the footing and a fixing length for the hollow concrete layer in the circumferential direction of the concrete pile with a shell steel pipe are circumferentially connected to each other in advance. There has been proposed a method of embedding along the axial direction at intervals (Patent Documents 1 and 2). In this case, the end part of the outer shell steel pipe that is covered over the entire length of the pile and that protrudes from the ground surface is removed by fusing etc., and the hollow concrete layer exposed at the trace is further dismantled Then, the reinforcing bars embedded inside are exposed. And the reinforcing bar exposed from this edge part is utilized as a pile head reinforcement.
Japanese Patent Laid-Open No. 7-18675 (see FIGS. 1 and 2) JP-A-6-220842 (see FIG. 2)

When manufacturing the concrete pile with a shell steel pipe of the above-mentioned patent documents 1 and 2, it is necessary to ensure covering of embedded reinforcing bars, such as a cage reinforcing bar. Therefore, in the centrifugal molding process of the hollow concrete body, measures are taken in advance to prevent the cage rebar or the like from moving with respect to the outer shell steel pipe. Specifically, a general method is to weld metal spacers to places on the inner surface of the outer shell steel pipe, and then spot-weld cage rebars and the like. However, in the outer shell steel pipe with an inner diameter that prevents the operator from entering the inside, it is relatively easy to install the spacer at a position near the end of the steel pipe. The difficulty increases as the distance from the increases. Even if the operator can enter the inside, if the inner diameter of the outer shell steel pipe is small, the welding work is performed in a narrow space, which is not easy. Moreover, as the pile head treatment method that uses such buried reinforcing bars as pile head reinforcing bars (pile head joint reinforcing bars) has become widespread, the total length of the buried reinforcing bars tends to increase. Development of technology to fix pile head reinforcing bars easily and reliably in the area has been desired.

  The present invention has been made in view of the situation of the prior art as described above. A cylindrical pile head reinforcing bar embedded in the hollow concrete body on the inner surface of the outer shell steel pipe is used regardless of the inner diameter of the outer shell steel pipe. A method for manufacturing a concrete pile with a shell steel pipe that can be easily installed in a certain position in the shell steel pipe and can also be applied to a pile head reinforcement with a long overall length, and a shell steel pipe obtained thereby The purpose is to provide concrete piles.

In order to solve the above-mentioned problems of the prior art, in the concrete pile with an outer shell steel pipe according to claim 1, the steel pipe as the outer shell, the cylindrical concrete body provided in close contact with the inner side of the steel pipe, the concrete body A pile head reinforcing bar assembled in a cylindrical shape coaxially embedded with one end of the steel pipe being locked to one end of the steel pipe, and the other end of the pile head reinforcing bar is connected to the inner surface of the steel pipe. A technical means is provided that includes a supporting member embedded in the concrete body in a state of being locked at a concentric position spaced from the inner surface of the steel pipe by elastic contact with the inner surface of the concrete body. The support member is preferably an annularly bent reinforcing bar that is larger than the inner diameter of the steel pipe and can be elastically deformed in the direction of diameter reduction.

According to a third aspect of the present invention, there is provided a method for manufacturing a concrete pile with a shell steel pipe comprising at least a pile head reinforcing bar assembled in a cylindrical shape with a plurality of main bars shorter than the total length of a steel pipe serving as a shell and a hoop bar surrounding them. At the other end, a step of attaching a support member made of an annularly bent reinforcing bar that is elastically deformable in the direction of diameter reduction in a free state in a free state, and reducing the diameter of the support member while resisting its elasticity The head reinforcement is inserted from the other end side to a predetermined position inside the outer steel pipe, and the other end of the pile head reinforcement is inserted from the inner surface of the steel pipe by elastically contacting the support member with the inner surface of the steel pipe. A step of locking at a concentric position at a predetermined interval; a pile head reinforcing bar with the support member provided at the other end by locking one end side of the main bar of the pile head reinforcing bar to one end portion of the steel pipe Of fixing the whole of the shaft coaxially, and these pile head reinforcing bars Injected amount of expandable concrete fine supporting member is embedded in the steel pipe, is characterized in further comprising a step of forming integrally a cylindrical concrete bodies on the inner surface of the steel pipe by centrifugal molding.

In the concrete pile with an outer shell steel pipe and the manufacturing method thereof according to the present invention, the following effects can be obtained by adopting the above configuration.
(1) At least the end (other end side) of the cylindrical pile head reinforcement in the insertion direction with respect to the outer shell steel pipe is attached with a support member that is larger than the inner diameter of the steel pipe and can be elastically deformed in the reduced diameter direction in a free state. Therefore, in the middle part in the longitudinal direction inside the outer shell steel pipe, the support member elastically abuts against the inner surface of the steel pipe so that the other end side of the pile head reinforcing bar is spaced from the inner surface of the steel pipe by a predetermined distance. Lock in concentric position. Therefore, if one end side of the pile head reinforcing bar is locked at a concentric position at one end of the outer shell steel pipe by an appropriate means, the pile head reinforcing bar is coaxially installed and fixed to the outer shell steel pipe. The pile head reinforcing bars are not displaced in the centrifugal forming process of the concrete body, and can be reliably embedded in the concrete body.
(2) At the other end side of the pile head reinforcement inserted in the inner back part of the outer shell steel pipe, the installation position is fixed only by the elastic force of the support member, and the conventional fixing work by welding becomes unnecessary. Therefore, it is only necessary to insert it into the inner part of the outer shell steel pipe, and the workability is very good.
(3) Since it is not necessary for the operator to enter the inner part of the outer shell steel pipe in the installation work of the pile head reinforcement in the outer shell steel pipe, it can also be applied to the outer shell steel pipe having a small inner diameter. There is no problem in using a long pile head reinforcement.
(4) If a reinforcing member bent in an annular shape that is larger than the inner diameter of the outer shell steel tube and can be elastically deformed in the reduced diameter direction is used as a support member for positioning on the other end side of the pile head reinforcing bar, the outer shell There is an advantage that it can be applied even when the inner diameter of the steel pipe is slightly increased or decreased, and since it can be easily bent, it can be manufactured at low cost.

  As described above, the concrete pile with outer shell steel pipe according to the present invention has a cylindrical pile head reinforcing bar embedded in the hollow concrete body on the inner surface side of the outer shell steel pipe. A major feature is that the fixing work of the pile head reinforcement, which is the previous stage of injecting expansive concrete, has been streamlined by adopting a structure that is fixed only by the elastic force of the support member in the middle part (inner back part). There is. That is, when attaching the pile head reinforcement bars, the inner surface of the outer shell steel pipe does not require any processing and is simply inserted. Therefore, there is an advantage that it can be easily and reliably installed even by a skilled person. is there. The material of the supporting member used in the present invention is not limited to metal, and synthetic resin can be used, but steel such as deformed reinforcing bar and spring steel is preferable. As the shape, various forms can be selected in addition to a bar shape or a plate shape. In addition, you may arrange | position the number of support members in several places of an axial direction according to the shape, the full length of a pile head reinforcement, etc. FIG. Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the present invention is of course not limited to these embodiments, and within the technical idea of the present invention, such as changes in the material, shape, quantity, and position of each component. Of course, various modifications can be made.

  FIG. 1 is a longitudinal sectional view showing a first embodiment of a concrete pile with an outer shell steel pipe according to the present invention, and FIG. 2 is a sectional view taken along line AA in FIG. In the illustrated concrete pile 1 with an outer shell steel pipe, a cylindrical concrete body 3 is integrally formed on the inner surface of the outer shell steel pipe 2, and end plates 4 are provided on both end portions thereof. Further, inside the concrete body 3, a pile head reinforcing bar 5 assembled in a cylindrical shape by a plurality of main bars 5a shorter than the entire length of the outer shell steel pipe 2 and the concrete body 3 and a plurality of hoop bars 5b surrounding them. Are embedded, and one end portions of the plurality of main bars 5 a are coupled to the end plate 4. On the other hand, a support member 6 to be described later is coupled to the other end of the pile head reinforcing bar 5 by means such as binding to a plurality of main bars 5a, and as shown in FIG. Is in contact with the inner circumferential surface at four locations on the circumference.

FIGS. 3A and 3B are a front view and a side view of the support member 6. The support member 6 is composed of a single reinforcing bar that is larger than the inner diameter of the outer shell steel pipe 2 in the free state and is bent in an annular shape that can be elastically deformed in the reduced diameter direction. The dimensions, materials, and the like are selected so that the inner surface of the shell steel pipe 2 is elastically contacted at four locations on the circumference. Note that the support member 6 used in the present invention is used under the condition that it can be elastically deformed. The shape of the support member 6 is such that two portions 6a located at opposite positions across the annular center are formed substantially linearly, and an arc portion 6b between these straight portions 6a is the inner periphery of the outer shell steel pipe 2 It is formed on a circular arc close to the curvature of the surface, and both end portions intersect to form a surplus length portion 6c. Therefore, the vicinity of the boundary portion between the straight portion 6a and the arc portion 6b and the end portion of the extra length portion 6c come into contact with the inner peripheral surface of the outer shell steel pipe 2.

  Next, the manufacturing method of the concrete pile with a shell steel pipe concerning this invention is demonstrated, referring FIG. 4 and FIG. FIG. 4 is a transverse sectional view showing a state in which the pile head reinforcing bars 5 are fixed inside the outer shell steel pipe 2, and corresponds to a sectional view taken along the line AA of FIG. FIG. 5 is a longitudinal sectional view showing a state in which the pile head reinforcing bars 5 are fixed inside the outer shell steel pipe 2. First, a pile head reinforcing bar 5 is prepared in which a plurality of main bars 5a and hoop bars 5b are assembled in a cylindrical shape with their intersections fixed by binding wires or the like. Next, the support member 6 is attached to the end of the pile head reinforcing bar 5. As shown in FIG. 4, the attachment method is as follows: binding wires (not shown) at three points of the main reinforcing bar 5a near the center of the arc part 6b and the two main reinforcing bars 5a in contact with the straight line parts 6a located on both sides thereof. To fix. The pile head reinforcing bar 5 having the support member 6 attached to the end thereof is contracted while resisting the elasticity of the extra length portion 6c side of the support member 6 so that the whole is smaller than the inner diameter of the outer shell steel pipe 2. It inserts into the inside of the outer shell steel pipe 2 from the support member 6 side, and stops at the position where the opposite end protrudes slightly. In this state, after welding the end plate 4 made of an annular disk substantially concentrically to the end of each main reinforcing bar 5a of the pile head reinforcing bar 5 protruding from the end surface of the outer shell steel pipe 2, the pile head reinforcing bar 5 is pushed further into the interior, and the end plate 4 is welded in a state where the end plate 4 is in contact with the end surface of the outer shell steel pipe 2. Needless to say, the end plate 4 is also welded to the other end side of the outer shell steel pipe 2 for subsequent centrifugal forming.

When the end plate 4 integrated with the main reinforcing bar 5a of the pile head reinforcing bar 5 is fixed to the end portion of the outer shell steel pipe 2, as shown in FIG. 6 is elastically abutting against the inner surface of the outer shell steel pipe 2 to lock the other end of the pile head reinforcing bar 5 at a concentric position at a predetermined interval from the inner surface of the outer shell steel pipe 2. Therefore, the entire pile head reinforcing bar 5 is fixed at a substantially concentric position at a predetermined interval from the inner surface of the outer shell steel pipe 2. An amount of expansive concrete in which the pile head reinforcing bars 5 and the support member 6 are buried is poured into the outer shell steel pipe 2, and the cylindrical concrete body 3 is made into the inner surface of the outer shell steel pipe 2 by a known centrifugal forming means. The concrete pile 1 with an outer shell steel pipe is obtained by forming it integrally.

  FIG. 6 is a cross-sectional view showing a usage state of the concrete pile 1 with an outer shell steel pipe according to the present invention. The upper shell steel pipe 2 is blown from a predetermined height position (about 100 mm) from the abandoned concrete surface provided on the surface portion of the ground 7 with respect to the protruding portion of the concrete pile 1 with the outer shell steel pipe placed on the ground 7 Remove by etc. Further, the exposed concrete body 3 is disassembled to expose the main reinforcement 5a of the pile head reinforcement 5 embedded therein. The hoop line 5b is removed as necessary. The pile head is buried in the footing by connecting the main reinforcement of the foundation beam to the exposed main reinforcement 5a and placing concrete.

  FIG. 7 is a front view of a support member according to the second embodiment, and FIG. 8 is a cross-sectional view of a concrete pile with an outer shell steel pipe using the support member. In the present embodiment and subsequent embodiments, the same portions are denoted by the same reference numerals, and the description of the overlapping portions is omitted. The illustrated support member 9 is composed of a single reinforcing bar bent into a substantially pentagonal shape, and both end portions thereof are bent inward. The support member 9 is larger than the inner diameter of the outer shell steel pipe 2 in a free state, and can be elastically deformed in the direction of diameter reduction. In the concrete pile 8 with the outer shell steel pipe shown in FIG. 8, the supporting members 9 are alternately installed on the inside and outside of the main reinforcing bar 5 a of the pile head reinforcing bar 5, and the five main reinforcing bars 5 a located on the outer side. They are united at the intersection. The pile head reinforcing bar 5 with the support member 9 attached to the end is reduced in diameter within a range in which it can be elastically deformed by pulling both bent portions closest to the free end side of the support member 9 in the proximity direction. It inserts in the inside of the outer shell steel pipe 2 in the state. After the insertion, it is elastically brought into contact with the inner surface of the outer shell steel pipe 2 at five points, so that no positional deviation occurs in the subsequent manufacturing process.

  FIG. 9 is a front view of a support member according to the third embodiment, and FIG. 10 is a cross-sectional view of a concrete pile with an outer shell steel pipe using the support member. The illustrated support member 11 is formed by bending a single reinforcing bar into a substantially oval shape and separating both free ends by one linear portion 11a. The support member 11 is partly larger than the inner diameter of the outer shell steel pipe 2 in a free state, and can be elastically deformed in the direction of diameter reduction. In the concrete pile 10 with an outer shell steel pipe shown in FIG. 10, the supporting member 11 is in contact with the main reinforcing bar 5a located at the center of both arc portions 11b and the other straight portion 11a. Are bound at the intersection with the main muscle 5a, and are fixed at four locations. In this case, since the portion on the free end side of the circular arc portion 11b can be deformed, this portion is inserted into the outer shell steel pipe 2 while being bent inward within the elastic range. The inner surface of the outer shell steel pipe 2 is elastically contacted in the vicinity of both end portions of both the arc portions 11b, that is, at four locations.

FIG. 11 is a front view of a support member according to the fourth embodiment, and FIG. 12 is a transverse sectional view of a concrete pile 12 with an outer shell steel pipe using the support member. The illustrated support member 13 is obtained by bending one reinforcing bar, and two of them are used as one set. Of course, three or more piles can be used depending on the pile diameter and the number of main bars. As for the shape, both end portions 13a are each formed in an arc shape of approximately 3/4, and an intermediate portion 13b connecting these both end portions 13a is formed in an arc shape in the opposite direction. As shown in FIG. 12, the usage method is such that the main reinforcing bar 5 a of the pile head reinforcing bar 5 is bound at three positions of the intermediate portion 13 b and is located at an opposite position across the axis of the pile head reinforcing bar 5. It is similarly attached to the main bar 5a. The support member 13 is larger than the inner dimension of the corresponding position of the outer shell steel pipe 2 in a free state in which the support member 13 is simply attached to a predetermined position of the pile head reinforcing bar 5, and can be elastically deformed in accordance with the dimension when inserted. ing. When inserted into the outer shell steel pipe 2, both end portions 13a are bent inward within a range in which elastic deformation is possible.

  13 to 15 show a fifth embodiment of the present invention. 13 and 14 are a front view and a bottom view of the support member, and FIG. 15 is a cross-sectional view of a concrete pile with an outer shell steel pipe using the support member. The support member 15 used in this embodiment is constructed by standing up a curved piece 15b made of a plurality of spring steels in a state in which the bent pieces 15b made of a plurality of spring steels are inclined radially outward at equal intervals on the outer peripheral edge of a metal annular disk 15a. is there. In the free state before being inserted into the outer shell steel pipe 2, the outer diameter on the free end side of the curved piece 15b is larger than the inner diameter of the outer shell steel pipe 2, so that the curved piece 15b falls down in the axial direction during insertion. It is elastically deformed to reduce the diameter. The annular disk 15a is provided with a plurality of through holes 15c. The support member 15 is used by fitting the through hole 15c in such an orientation that the fixed end side of the curved piece 15b is in the insertion direction of the pile head reinforcing bar 5 with respect to the end of the main bar 5a of the pile head reinforcing bar 5. Further, they may be fixed by binding the vicinity of the fitting portions. If it inserts in the inside of the outer shell steel pipe 2 in this state, each bending piece 15b will be inserted to a predetermined position, elastically deforming so that it may fall to the axial center side. Since each curved piece 15b elastically contacts the inner surface of the outer shell steel pipe 2 after the insertion, the pile head reinforcing bar 5 is reliably fixed in position.

  In addition, in the concrete pile with outer shell steel pipe of the above-described embodiment, an example in which one or a pair of support members are attached to the end of the pile head reinforcing bar has been described. Of course, a plurality of support members can be provided in the axial direction. Further, as a method for connecting the main bar to the end plate, means such as screwing may be applied in addition to welding. In addition, when it is difficult to bind the support member and the main reinforcement of the pile head reinforcement, the method of connecting the support member and the pile reinforcement, such as binding to the hoop of the pile reinforcement, can be selected as appropriate. it can.

It is the longitudinal cross-sectional view which showed the 1st Example of the concrete pile with a shell steel pipe concerning this invention. It is the sectional view on the AA line of FIG. It is the front view and side view of a supporting member which are used in the first embodiment. It is the sectional view on the AA line of FIG. In the manufacturing method of the concrete pile with an outer shell steel pipe concerning the present invention, it is a longitudinal section of the state where the pile head reinforcement was fixed inside the outer shell steel pipe. It is the fragmentary longitudinal cross-section which showed the use condition of the concrete pile with an outer shell steel pipe concerning the present invention. It is a front view of the supporting member used in the second embodiment. It is the longitudinal cross-sectional view which showed the 2nd Example of the concrete pile with an outer shell steel pipe concerning this invention. It is a front view of the supporting member used in a 3rd example. It is the longitudinal cross-sectional view which showed the 3rd Example of the concrete pile with an outer shell steel pipe concerning this invention. It is a front view of the supporting member used in the 4th example. It is the longitudinal cross-sectional view which showed the 4th Example of the concrete pile with an outer shell steel pipe concerning this invention. It is a front view of the supporting member used in a 5th example. It is a bottom view of the supporting member used in the fifth embodiment. It is the longitudinal cross-sectional view which showed the 5th Example of the concrete pile with an outer shell steel pipe concerning this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1,8,10,12,14 ... Concrete pile with outer shell steel pipe, 2 ... Outer shell steel pipe, 3 ... Concrete body, 4 ... End plate, 5 ... Pile head reinforcement, 5a ... Main reinforcement, 5b ... Hoop reinforcement, 6 , 9, 11, 13, 15 ... support members, 7 ... ground

Claims (3)

  A steel pipe as an outer shell, a cylindrical concrete body provided in close contact with the inside of the steel pipe, and a cylinder embedded coaxially with one end of the concrete body being engaged with one end of the steel pipe The pile head reinforcement bars assembled in a shape and the other end side of the pile head reinforcement bars are elastically brought into contact with the inner surface of the steel pipe to be locked at a concentric position spaced from the inner surface of the steel pipe. A concrete pile with an outer shell steel pipe, comprising a support member embedded in the concrete body in a state of being made. 2. The concrete pile with outer shell steel pipe according to claim 1, wherein the support member is an annularly bent reinforcing bar that is elastically deformable in a direction of diameter reduction larger than an inner diameter of the steel pipe. At least the other ends of the pile head reinforcement bars, which are assembled in a cylindrical shape with multiple main bars shorter than the total length of the outer steel pipe and the hoops surrounding them, are elastic in the direction of diameter reduction in a free state larger than the inner diameter of the steel pipe. A step of attaching a deformable annularly bent support member, and reducing the diameter of the support member while resisting its elasticity, and inserting the pile head reinforcement from the other end side to a predetermined position inside the outer steel pipe A step of locking the other end side of the pile head reinforcing bar at a concentric position at a predetermined interval from the inner surface of the steel pipe by the support member resiliently contacting the inner surface of the steel pipe; A step of fixing the whole pile head reinforcing bar coaxially with the support member provided on the other end side by locking one end side of the main reinforcing bar to one end portion of the steel pipe, and these pile head reinforcing bars and support The amount of expansive concrete in which the member is buried is placed inside the steel pipe. Input, and a manufacturing method of a concrete pile with an outer shell steel pipe characterized in that it comprises a step of forming integrally a cylindrical concrete bodies on the inner surface of the steel pipe by centrifugal molding.

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