JP2006161543A - Pile head treating method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve problems in various methods for treating a pile head of a cast-in-place concrete pile, among which there are many methods for easily removing concrete around a main reinforcement, but in this case, it is hard to remove concrete at the center part. <P>SOLUTION: Concrete at the center part is pushed into a special cylindrical body, and the cylindrical body and concrete are pulled up simultaneously. At this time, adhesion at the side face of the cylindrical body is eliminated, and a mesh reinforcement is used for a bottom face to rip off and remove concrete almost at right angles to the face while the concrete is unhardened. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a pile head processing method for cast-in-place reinforced concrete piles.

  Pile head treatment method is one of the important technical issues when cast-in-place reinforced concrete piles are used for civil engineering and construction foundation works. There have been various methods than before, but there are many that reduce the volume of concrete removed at the same time that the concrete around the main reinforcement of the pile is separated from the main reinforcement. An example of this is that of Non-Patent Document 1.

  Of these, P.I. The method of (d) and (e) of Fig. 3 in Fig. 27 is related to the present application.

Specialized magazine foundation engineering February, 2005 issue General engineering works research institute issue

  The pile head treatment method described above can easily remove the concrete near the main rebar, but cannot remove the concrete at the core in the center of the pile. Especially in recent years, the pile diameter has increased, and this problem has become more important.

  As a means for solving the problem, a method is adopted in which concrete at the center of the pile is put into a special cylinder and the cylindrical body of the special cylinder, the reinforcing bar, and the concrete are simultaneously extracted. The configuration of this special cylinder is cylindrical, the upper surface is open, and the lower surface has a mesh-like reinforcing bar. The minimum size of this mesh is the maximum value that can pass through the largest coarse aggregate of concrete. Is a range in which the semi-cured concrete does not fall when it is lifted from the mesh, and details thereof are shown in the best mode for carrying out the invention.

  The side is cylindrical, and this material is a cardboard cylindrical form, steel pipe, synthetic resin cylindrical pipe, etc., and a synthetic resin corrugated sheet, iron plate corrugated sheet, etc. are wrapped around this, and concrete is separated outside this Wrap the sheet so that the concrete does not enter the low valley as seen from the outside of the corrugated sheet, and maintain the elasticity of the corrugated peak.

  Pack the packing material down from the bottom of the gap between the corrugated plate and the cylinder, or between the cylinder and the concrete separation sheet, or make the bottom of the corrugated plate slightly shorter here. Use a concrete retaining ring.

  Polyethylene foam may be used in place of the corrugated sheet. In the case of foamed polyethylene, there is no wave portion, but the whole is sponge-like and uses this elasticity. In this case, a packing material and a concrete retaining ring are not required, but a powder or liquid friction force reducing material is applied to the cylindrical body in order to reduce the friction between the cylindrical body and the foamed polyethylene. Or a concrete separation sheet is used similarly to the case of a corrugated sheet.

  If the shape is wound cardboard, one side is corrugated and the other side is flat, the material is water-resistant paper or synthetic resin, and the strength can withstand the lateral pressure of concrete, the flat surface is used on the outside. The plate and the concrete separation sheet are integrated.

  The shape of the bottom is shown in the best mode for carrying out the invention, but the concrete on the bottom is united vertically through the mesh, but the concrete can be peeled off at right angles to this surface by the following two means It becomes. The first is when the concrete has not hardened sufficiently. The second is that the adhesion between the side surface of the cylinder and the concrete is eliminated to maintain elasticity and eliminate the adhesion resistance of the side surface. In this case, it is necessary to absorb the error by elasticity because it cannot cope with the dimensional error of the product if there is no adhesion. This detail is given in the best mode for carrying out the invention. In this way, the cylindrical body can be easily pulled out from the concrete in this length direction, and at this time, the concrete and the reinforcing bar in the cylindrical body are also pulled out at the same time.

  According to such a pile head processing method of the present invention, since the concrete of the core portion at the center of the pile can be easily removed, the concrete around the main reinforcing bar on the side surface can be removed with a breaker or the like more easily than before. . This is because the cross section is thinner than before. In addition, since it can be broken by hitting it with a large hammer, noise and vibration are reduced compared to the case of using a breaker. Moreover, if the method of a nonpatent literature 1 is used simultaneously, a pile head process can be performed still more efficiently.

  Embodiments of the present invention will be described below. A special cylindrical body A as shown in FIGS. 2 and 3 is made based on the cylindrical body 1 as shown in FIG. 2 is a side view, and FIG. 3 is a plan view. The height of the special cylinder A is substantially the same as the height required for the pile head processing. The material of the cylindrical body 1 is a cardboard cylindrical form, a steel pipe, a synthetic resin cylindrical pipe, or the like. A corrugated plate 2 made of synthetic resin or iron plate is wound around the outside of the cylindrical body 1. A concrete separation sheet 3 is further wound around the outside of the corrugated sheet 2. For this material, use a flat paddy paddy sheet or equivalent, and use a thicker or thicker one when the concrete side pressure is high and the strength is insufficient. The purpose of these uses is as described in the means for solving the problems. As shown in FIG. 4, the concrete separating sheet 3 is partially overlapped between a and b and fixed with an adhesive tape 4, or a wire is wound around the entire periphery and fixed. A packing material 6 is packed in a portion below the gap 5 between the cylindrical body 1 and the corrugated sheet 2 and between the corrugated sheet 2 and the concrete separating sheet 3 to prevent intrusion of concrete. Alternatively, instead of using this packing material 6, the corrugated sheet 2 is slightly shortened and a concrete retaining ring 7 is used here. The positions of the packing material 6 are c to d in FIG. 2 and the material is foamed polyethylene or the like, which is formed into a corrugated shape. The position of the concrete retaining ring 7 is ef in FIG. 2, and the material is also foamed polyethylene or the like. Sheets may be wound several times.

  As the bottom surface, a rebar rod 11 formed of an L-type reinforcing bar 8, a hoop bar 9, and a ring bar 10 is used. The concrete is cast using a treme having a normal inner diameter of 20 to 30 cm and a small hole treme having an inner diameter of 5 to 15 cm. A small-diameter mesh rebar 12 having a hole portion into which a small-diameter tremey is inserted at the end of a 5-10 cm grid-like mesh rebar, welded wire mesh, rebar wire mesh, etc. is cut into a circle as shown in FIG. When the mesh is 5 cm, if one of the central portions is taken as shown in FIG. A small hole mesh rebar 12 is overlapped on the rebar rod 11 and the required portions are joined by smoothing an iron wire, a bolt, welding or the like. It is fixed so that it can withstand the upward force of the concrete described below as well as overlapping from above. The hoop bar 9 of the rebar rod with small hole mesh rebar 20 is drilled with a wire 13 in the cylindrical body 1 and fixed at several places with a wire 13 as shown in FIG. 4, and the cylinder 1 and the rebar bar 20 with small hole mesh rebar are joined. Then, a special cylindrical body A is prepared.

  Next, the pile reinforcing bar is inserted into the pile excavation hole with a crane. A spacer 15 is welded and attached to the main reinforcing bar 14 of the reinforcing bar. Pile concrete is placed using ordinary tremy, and when the upper surface comes up and reaches the planned finished surface of the pile, that is, slightly below the position of g in FIG. Suspend A from above. The L-type reinforcing bar 8 is fixed to the main reinforcing bar 14 of the pile so that it does not fall any further when it reaches a predetermined position and does not move upward. In the fixing method, the wood is sandwiched between the main reinforcing bar 14 and the L-type reinforcing bar 8 and is clamped from the outside with an annealed iron wire or a U-bolt. Next, 1 to 2 m of a small hole diameter tremey is inserted into the concrete from the center of the small hole diameter mesh reinforcing bar 12, and the concrete above the vicinity of df in FIG. The maximum size of the coarse aggregate of concrete is 25 mm to 40 mm. In the case of 25 mm, the minimum value of the mesh size of the small-diameter mesh rebar 12 is about 30 mm so that this aggregate can pass through, but with a margin of 40 to 50 mm. To do. The concrete extruded from the small pore mesh rebar 12 is pushed up through the mesh.

  The concrete hardens gradually and the slump is 0. Raise it when it is a little later. What is pulled up is an L-type rebar 8, a hoop bar 9, a ring bar 10, a rebar rod 20 with a small-hole mesh rebar composed of a small-hole-diameter rebar 12, a semi-hardened concrete 16 and a cylindrical body 1, and an upper portion of the L-type rebar 8. Are simultaneously lifted, and in the case of FIG. 3, four are simultaneously lifted with a crane or a gate by a jack.

  When the pile diameter is large, the auxiliary reinforcing bar 17 is embedded in the concrete 16 and pulled up simultaneously with the L-shaped reinforcing bar 8. Thereafter, the corrugated plate 2 is removed, and then the concrete separating sheet is pulled off from the concrete by pulling the end a in FIG. 4 toward the center. The concrete of the core part of the center part of a pile is removed by the above.

  Another embodiment. A mesh rebar 18 having a hole for entering a normal tremy is connected to a reinforcing bar 11 to form a special cylindrical body A, which is connected to a main reinforcing bar 14 of a pile and built in a drilling hole with a crane or the like. After installing the main reinforcing bar 14 of the pile, the special cylindrical body A is suspended and fixed to the main reinforcing bar 14. When concrete is placed with ordinary tremy and the top surface of the concrete rises to a little below g in Fig. 2, the ordinary treme is pulled up and the hole part of the mesh rebar 18 is removed with the small mesh rebar 19 with the hole part into which the small-diameter treme enters. In order to prevent it from moving up and down, an operator enters inside and fixes it with annealed iron wire or bolts, and places the remaining concrete with a small hole treme. This will reduce the interruption time for placing concrete. The other parts are the same as in the first embodiment.

It is a perspective view of the cylinder for showing the embodiment of the present invention. It is a side view which shows the special cylindrical body of this invention. It is a top view which shows the special cylinder body of this invention. It is a partial enlarged view of the plane of the special cylinder of the present invention. It is a small hole mesh rebar used in the present invention. It is a mesh rebar used in the present invention. It is a small mesh rebar used in the present invention.

Explanation of symbols

A Special cylinder
1 Cylindrical body
2 Corrugated sheet
3 Concrete separation sheet 4 Adhesive tape
5 Clearance
6 Packing material
7 Concrete retaining ring
8 L type rebar
9 Hoop muscle
10 Ring muscle
11 Reinforcing bar
12 Small pore mesh rebar
13 Wire
14 Main reinforcement
15 Spacer
16 concrete
17 Auxiliary rebar
18 Mesh rebar
19 Small mesh rebar
20 Rebar rod with small hole mesh rebar

Claims (4)

  The purpose is to remove the low-strength concrete of the cast-in-place reinforced concrete pile head. Although the body is installed, the installation process is that concrete is placed in the excavation hole where the rebar is installed by ordinary tremy, and the upper surface of the concrete in the excavation hole rises upward, and the lower surface of the special cylinder is planned to be installed slightly. At this time, the treme is lifted to stop the concrete placement, and the special cylinder is suspended from the top of the excavation hole with a wire, etc. In order to stop the concrete from being pushed up from below by the concrete, the upper end of the special cylinder is fixed to the main reinforcing bar of the pile and fixed so that it does not move up or down. Insert a small-diameter treme into the tremey space and insert it into the concrete that has already been placed, and then place the concrete for the second time. Push the low-strength concrete upward from the mesh on the lower surface of the special cylinder, and the concrete is half-hardened. This low-strength concrete is lifted and removed together with a special cylindrical body and rebar rod. The structure of this special cylindrical body is an opening on the upper surface and a reticulated mesh on the lower surface. In some cases, the reinforcing bar is used, and the reinforcing bar is integrally attached to the reinforcing bar so that the reinforcing bar is also installed when necessary, and the minimum value of the mesh of the bottom part of the reinforcing bar is as follows. The maximum coarse aggregate of concrete can pass through. The maximum value is the range where semi-hardened concrete does not fall when suspended from the mesh, and the side is the side of the cylinder Then, wrap the corrugated sheet around this outside and wrap the concrete separation sheet around this outside so that the concrete does not enter the low valley part when viewed from the outer surface of the corrugated sheet, and maintain the elasticity of the corrugated part of the corrugated sheet, Pack the packing material downward so that the concrete does not enter from the valley of the gap between the corrugated sheet and the cylindrical body and the cylindrical body and the concrete separating sheet, or slightly shorten the lower part of the corrugated sheet and place the concrete here. It consists of a structure with a retaining ring, and lifts and removes low-strength concrete, cylinders, and reinforcing rods as described above, and then removes the corrugated sheet and concrete separation sheet so as to peel off in the center direction, and then the remaining main reinforcing bars. Pile head processing method to remove concrete around.   The purpose is to remove the low-strength concrete of the cast-in-place reinforced concrete pile head. Although the body is installed in the same manner as in claim 1, the installation process is different from that in claim 1 in that it is before the start of placing concrete and a rebar rod is installed in the excavation hole and then a special cylinder is attached to the main rebar. Alternatively, a reinforcing bar with a special cylindrical body attached to the main reinforcing bar is installed in the excavation hole, and then concrete is placed. In this case, a mesh rebar with a hole for a normal tremey is installed on the bottom surface of the special cylinder, and concrete is cast with the normal tremey, so that the top surface of this concrete is slightly below the bottom surface of the special cylinder. When it comes up, the treme is lifted and removed, and this hole is covered with a small mesh rebar with a hole into which a small hole treme is inserted, and the remaining concrete is placed again with a small hole treme. Other parts are the same as those of the first aspect.   The cylindrical body according to claim 1 or claim 2 is any one of a cardboard cylindrical frame, a steel pipe, a synthetic resin cylindrical pipe, or an equivalent product, and the corrugated sheet is either a synthetic resin corrugated sheet or an iron sheet corrugated sheet, Or the pile head processing method of Claim 1 or Claim 2 which is an equivalent product.   Use foamed polyethylene instead of the corrugated sheet and packing material according to claims 1 to 3, or use foamed polyethylene instead of the corrugated sheet and the concrete retaining ring, or replace the corrugated sheet and the concrete separating sheet. The pile head according to any one of claims 1 to 3, wherein the two are integrated into one, like a corrugated cardboard, having water resistance and strength against concrete, and simultaneously using a packing material or a concrete retaining ring. Processing method.

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