JP2005048574A - Reinforcing method for reinforcement soil cement structure, and reinforcement soil cement structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce exfoliation of covering concrete and demonstrate a proper strength under excellent workability, construction efficiency and maintainability. <P>SOLUTION: In a reinforcing method for a reinforcement soil cement structure, a plastic hinge part 105 in the reinforcement soil cement structure, wherein a reinforcement bar is disposed in the soil cement, is restrained by a restraining body 108 such as a steel pipe. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a reinforcing method of a reinforcing bar soil cement structure and a reinforcing bar soil cement structure.

Soil cement is sometimes used instead of concrete when forming underground structures such as underground continuous walls and piles. In general, since soil cement has lower strength than concrete, it has been intended to develop desired strength by increasing the cross section of the frame and covering the reinforcing bars. Therefore, a tubular steel material with reinforcing bars attached to the inner or outer surface is used as the core material to be dropped into the soil cement column, aiming to shorten the construction time, reduce the soil discharge, and reduce the material cost. However, a structure in which a cylindrical steel material, a reinforcing bar, and a soil cement inside a constrained steel pipe are responsible for bending stress and shear stress (see Patent Document 1) has been proposed.
Japanese Patent Laid-Open No. 11-247188

  When performing restraint with a steel material such as a steel pipe over the entire extending direction of the rebar soil cement structure as in the prior art, for example, it is difficult to work when passing the rebar placed in the soil cement through the steel material such as the steel pipe. There is a tendency to reduce work efficiency. Furthermore, the length of the steel material for restraint becomes long, so that construction under a low head is difficult, and the workability may be lowered.

  In addition, it is fundamental that the steel pipe is set up at the same time as the reinforcing bar, and it is impossible to set up only the steel pipe after the creation of the reinforcing bar soil cement structure. There were also problems with poor sex.

  This also causes the problem that it is difficult to replace the steel pipe, and the corrosion of the steel pipe, that is, the life of the reinforcement work. In addition, it is difficult to remove and inspect and repair the steel pipe after the reinforced soil cement structure is subjected to an earthquake.

  Therefore, the present invention has been made in view of the above problems, and has a reinforced soil cement structure that can reduce peeling of covered concrete and exhibit appropriate strength under excellent workability, construction efficiency, and maintainability. The main object of the present invention is to provide a reinforcing method and a reinforced soil cement structure.

  The reinforcing method of a reinforcing bar soil cement structure of the present invention that solves the above-mentioned problem is characterized in that the plastic hinge part in the reinforcing bar soil cement structure in which reinforcing bars are arranged in the soil cement is restrained by a restraining body such as a steel pipe. (First invention).

  According to a second invention, in the first invention, between the plastic hinge portion and the rigid region, the thickness of the restraint body is at least 1 time and 1/10 times the cross-sectional height of the reinforced soil cement structure. The following gap is provided.

  A third invention is characterized in that, in the first or second invention, the thickness of the restraint is limited to a thickness that expresses a strength sufficient to restrain the plastic hinge portion. To do.

  In a fourth aspect of the present invention, in any one of the first to third aspects, when the reinforcing bar soil cement structure is a pile body, the restraint body has a length 0.5 to 2 times the pile body diameter. It is a steel pipe.

  A fifth invention is characterized in that, in any one of the first to third inventions, when the reinforcing bar soil cement structure is a wall, the restraint is a steel plate.

  A sixth invention is characterized in that, in any one of the first to fifth inventions, the restraining body is an annular synthetic resin or a sheet made of long fibers formed into an annular shape.

  A seventh invention is characterized in that, in any one of the first to sixth inventions, the restraint body is appropriately divided and used in the vertical direction of the reinforcing bar soil cement structure. Here, “divided” refers to a case in which a single restraint body that restrains the plastic hinge portion is cut and divided, and a plurality of restraint bodies that divide and share the restraint function to be performed as the restraint body. It can be assumed that (made as a single restraint) is used.

  As an example of cutting a single restraint body, when the restraint body is a steel pipe, a mode in which the steel pipe is cut into a ring shape and used can be assumed. On the other hand, as an example of using a plurality of restraining bodies that divide and share the restraining function to be performed as the restraining body, for example, when the restraining body is a steel pipe, the steel pipe length is 3 minutes of the length of the plastic hinge portion. A mode in which three steel pipes that are No. 1 are used can be assumed.

  According to an eighth aspect of the present invention, there is provided a reinforcing bar soil cement structure in which the plastic hinge portion is constrained by a restraining body such as a steel pipe.

  In addition, the problems disclosed by the present application and the solutions thereof will be clarified by the embodiments of the present invention and the drawings.

  According to the present invention, by restraining the plastic hinge part (including a part or the periphery thereof) without restraining by a restraint body such as a steel pipe over the entire extending direction of the reinforcing steel soil cement structure. There are various effects as described below.

  For example, the work at the time of passing the reinforcing bar arranged in the soil cement through the restraint body such as the steel pipe becomes easy, and the work efficiency is improved. Furthermore, since the steel material length is short, construction under a low head is also possible, and workability can be improved.

  In addition, the steel pipe (restraint body) is basically stood at the same time as the rebar, but it is also possible to stand, for example, only a steel pipe after the rebar soil cement structure is formed, and this has the effect of increasing work flexibility.

  This leads to the effect that the steel pipe can be replaced at the same time, and the corrosion of the steel pipe does not become the life of the reinforcing work, and the life of the reinforcing work can be extended by the maintenance of the steel pipe. In addition, after the steel reinforced soil cement structure is subjected to an earthquake, the steel pipe can be removed for inspection and repair.

  In addition, if the restraint is divided and used as appropriate in the vertical direction of the reinforcing bar soil cement structure, the effect of reducing the cost by reducing the material and improving the workability by suppressing the weight of the restraint alone can be obtained. Become.

  Furthermore, if an annular synthetic resin or a sheet of long fiber molded into an annular shape is used as the restraint, the weight of the restraint is further reduced to improve the workability, and the material of the restraint itself is rusted. Therefore, durability can be improved.

  Therefore, it is possible to provide a reinforcing bar soil cement structure reinforcing method and a reinforcing bar soil cement structure which can reduce covering concrete peeling and exhibit appropriate strength under excellent workability, construction efficiency and maintainability.

  Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a view showing a soil cement pile (reinforcing steel soil cement structure) in the present embodiment. The reinforcing method of a reinforcing bar soil cement structure of the present invention pays attention to the weak point of soil cement when compared with concrete. For example, this is a technique for suppressing phenomena that are difficult to expect in concrete, such as shear compression failure when not in-plane walls, peeling of covered concrete before rebar buckling, and bond splitting in areas other than high rebar ratio and low shear span ratio regions.

  Reinforcing bar soil cement structure 100 shown in FIG. 1 can be assumed to be a reinforcing bar soil cement pile in which soil cement 102 is formed by kneading and solidifying in situ soil and cement included in ground 101 with an appropriate construction machine. In this reinforcing bar soil cement pile 100, a vertical reinforcing bar 103 as a main core material is arranged with an appropriate covering thickness on the inner periphery of the cross section of the soil cement 102 (in addition, the reinforcing bar 111 can be arranged appropriately).

  Such a reinforced soil cement pile 100 is fixed by a rigid region such as a footing 104 of a pier foundation and its head. That is, the stress derived from the footing 104 is received by the pile head. Therefore, when the footing 104 which is a rigid region exerts a stress having a horizontal element on the reinforced soil cement pile 100, a bending stress acts on the reinforced soil cement pile 100 with the pile head as an action point.

  Thus, if stress is received by a pile head, the plastic hinge part assumed in the appropriate position between the said pile head and the pile front-end will become a hinge at the time of the said bending stress acting. In FIG. 1, a steel pipe 108 is disposed with a gap 107 from the bottom surface 106 of the footing 104 with respect to the plastic hinge portion 105. The steel pipe 108 is an example of a restraining body that restrains the plastic hinge portion of the reinforcing bar soil cement structure in the present invention.

  By constraining the plastic hinge portion 105 by the steel pipe 108, it is possible to suppress splitting of the cover 109 (soil cement), and to cover the core material of the plastic hinge portion 105, that is, the vertical reinforcing bar 103 in this case and the outer periphery of the vertical reinforcing bar 103. The adhesion with the cover 109 is forcibly increased. Therefore, adhesion slip is suppressed and peeling of the cover is also reduced. In addition, by preventing adhesion slip due to splitting, it is possible to shift to an adhesion mechanism by supporting pressure. Furthermore, since the restrained soil cement shifts to the triaxial compression state, the strength is increased, and the strength against the oblique compression fracture is exhibited, and the toughness is also improved.

  If only the plastic hinge part 105 is restrained by the steel pipe 108 (restraint body), it is preferable in terms of construction cost and efficiency. Thus, in order to constrain only the plastic hinge part 105, for example, when the reinforced soil cement structure 100 is a pile body, the restraint body 108 such as the steel pipe has a length 0.5 to 2 times the pile body diameter. I can do it.

  Further, as described above, by providing a gap 107 of a predetermined distance between the plastic hinge portion 105 and the rigid region 104, the steel pipe 108 is not substantially subjected to bending stress from the rigid region 104 received by the pile head. it can. Accordingly, since the steel pipe 108 does not bear bending stress, the thickness of the restraint body such as the steel pipe 108 is limited to a thickness that expresses the strength that can restrain the plastic hinge portion 105. . Further, it is possible to avoid the plastic hinge part moving under the steel pipe. The gap 107 can be, for example, not less than 1 times the plate thickness of the restraining body 108 and not more than 1/10 times the cross-sectional height of the reinforcing bar soil cement structure 100.

  In addition, the restraining body 108 may be an annular synthetic resin or a long fiber sheet formed into an annular shape. As a result, the weight of the restraint is further reduced to improve the workability, and the durability of the restraint can be improved because the material of the restraint itself does not rust.

  Moreover, as shown in FIG. 1, the said restraint body can also be divided | segmented suitably in the perpendicular direction of a reinforcing bar soil cement structure. Thereby, the effects of reduction in cost due to material reduction and improvement in workability due to weight reduction of the divided restraint body 300 are further exhibited.

  FIG. 2 is a view showing a flat cross section of the underground continuous wall (reinforcement soil cement structure) in the present embodiment. In the above description, a pile body is assumed as the reinforcing bar soil cement structure, but an underground continuous wall can also be assumed. The underground continuous wall 200 here is a soil cement wall 202 obtained by kneading and solidifying the in-situ soil included in the ground 201 and cement. For example, a reinforcing bar 203 is disposed on the wall 202 as a core material.

  In the present invention, a steel plate 204 and a bar member 205 such as a reinforcing bar are employed as a restraining body for restraining the reinforcing bar soil cement structure. The steel plate 204 is disposed in contact with the side surface 206 so as to extend the side surface 206 of the wall body 202 downward (in the deep direction of the ground). As shown in FIG. 3, the arrangement is such that the top 207 of the wall 202 or the end 208 of each floor slab 210 passes through the gap 209 in the same manner as described above, and thereafter to the bottom of the wall 202 or between each floor slab 210. This is done up to the existing plastic hinge. As described above, according to the form of the reinforcing bar soil cement structure, if the arrangement mode of the restraint body is made to correspond, it is not limited to the pile body or the underground continuous wall, and the present invention is applied to various reinforcing bar soil cement structures. The invention can be applied.

  Although the present embodiment has been described above, the above examples are for facilitating the understanding of the present invention, and are not intended to limit the present invention. The present invention can be changed and improved without departing from the gist thereof, and the present invention includes equivalents thereof.

It is a figure which shows the soil cement pile (reinforcement soil cement structure) in this embodiment. It is a figure which shows the plane cross section of the underground continuous wall (reinforcement soil cement structure) in this embodiment. It is a figure which shows the side cross section of the underground continuous wall (reinforcement soil cement structure) in this embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Reinforcement soil cement structure, Reinforcement soil cement pile, Pile body 101, 201 Ground 102 Soil cement 103, 203 Vertical reinforcement, Core material 104 Footing of bridge pier foundation, Rigid area 105 Plastic hinge part 106 (Footing) bottom face 107 Gap 108 Steel pipe , Restraint body 109 covering 110 length (of steel pipe) 200 underground continuous wall, reinforcing bar soil cement structure 202 wall body 204 steel plate, restraining body 205 bar material 206 (of wall body) side face 207 (of wall body) Top 208 End of each floor slab 209 Gap 210 Each floor slab

Claims (8)

  A method for reinforcing a reinforcing bar soil cement structure, characterized in that a plastic hinge portion in a reinforcing bar soil cement structure in which reinforcing bars are arranged in a soil cement is restrained by a restraining body such as a steel pipe.   The gap between the plastic hinge part and the rigid region is provided with a gap that is not less than 1 times the plate thickness of the restraint and not more than 1/10 times the cross-sectional height of the reinforced soil cement structure. 2. A method for reinforcing a reinforcing bar soil cement structure according to 1.   3. The reinforcing bar soil cement structure according to claim 1, wherein the thickness of the restraint body is limited to a thickness that expresses a strength sufficient to restrain the plastic hinge portion. Reinforcement method.   When the reinforcing bar soil cement structure is a pile body, the restraint body is a steel pipe having a length 0.5 to 2 times the pile body diameter. The reinforcing method of the reinforcing bar soil cement structure as described.   The reinforcing method of a reinforcing bar soil cement structure according to any one of claims 1 to 3, wherein when the reinforcing bar soil cement structure is a wall body, the restraint body is a steel plate.   The reinforcing method of a reinforcing bar soil cement structure according to any one of claims 1 to 5, wherein the constraining body is a cyclic synthetic resin or a long fiber sheet formed into a ring shape.   The method for reinforcing a reinforcing bar soil cement structure according to any one of claims 1 to 6, wherein the restraint body is appropriately divided and used in a vertical direction of the reinforcing bar soil cement structure.   A reinforcing bar soil cement structure in which a plastic hinge part is restrained by a restraint body such as a steel pipe.

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