JPH0892965A - How to build a tubular structure - Google Patents

Abstract

(57) [Summary] [Purpose] To prevent cracks from occurring in the matchcast concrete block by making some efforts to join the matchcast concrete block and the base concrete in a tubular structure that introduces prestress. [Structure] Bottom block 10a and block 10 above it
b is assembled on a flexible support 21 and sewn up and down with a PC steel rod 12 to form a reference block 10 having a match cast surface on the upper surface, which is fixed on a base concrete 11 and a precast block is provided above it. Stack.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention has a height of, for example, 30 to 50.
The present invention relates to a method of constructing a large-diameter tubular structure for stacking matchcast type precast concrete blocks such as foundations of m bridge piers, precast caisson, and precast prestressed concrete wells (PC wells).

[0002] The present invention can be particularly suitably used when joining and constructing a large-diameter precast concrete block that divides a single-stage block into a plurality of pieces.

[0003]

2. Description of the Related Art In recent years, when constructing a concrete structure, the precast concrete block construction method, which enables production of members in parallel with cast-in-place concrete, has been increasingly adopted. The precast block construction method meets the demands such as shortening the construction period by preliminarily manufacturing the members without time and space restrictions, and improving the quality by being manufactured in a factory equipped with facilities. This is no exception in the field of civil engineering structures, and is widely used in bridges, roads, tunnel linings, etc.

PC for precast concrete block
In the method of binding with steel materials, the end face of the preceding production block is used as a formwork of the end face of the subsequent production block and concrete is successively cast to produce blocks with matching end faces by the so-called match cast method, and joining at the time of assembly A method of accurately constructing a surface is being used. This is because if the joint surface is not formed accurately, local stress concentration occurs at the mismatched portion of the joint surface when prestress is introduced, and the block may crack.

Further, in a large structure, not only the match cast concrete blocks divided in the block arranging direction are manufactured, but also the unit blocks in the arranging direction are further divided into a plurality of pieces to be precast. It is necessary to improve workability, which causes problems. For example, taking a tubular structure or a PC well as an example, it has been conventionally constructed by stacking concrete blocks preliminarily cut in a horizontal direction and precast by a match cast method. Furthermore, if the PC well with a large diameter is simply cut in a horizontal direction, the weight and size of the block will be excessive, and the heavy equipment and truck required for transportation and assembly will become large, which will impair economic efficiency. In addition, the precast concrete block divided vertically into a plurality of pieces will be manufactured. Such a match cast concrete block is placed on the foundation concrete manufactured by cast-in-place concrete at the construction position of the structure or on the PC well edge concrete (hereinafter collectively referred to as base concrete) driven into the ground. Place and assemble.

[0006] Since the base concrete is constructed on site rather than match cast, it is very difficult to individually install each of the divided pieces into a predetermined position.
Also, because the top surface of the base concrete is troweled evenly,
It is difficult to reproduce the accuracy equivalent to that of the match cast joint surface at the time of manufacturing the block by a simple method in which the horizontal and planar positioning for installing it on the site is simple.

In addition, the lowermost precast concrete block to be placed on the base concrete increases the degree of freedom as a result of the vertical division of the joint surface with the base concrete, and the joint surface with the base concrete is a block by the matchcast method. Since it is impossible to manufacture, it is difficult to match the joint surface with sufficient accuracy, and it is difficult to match the joint surface with sufficient accuracy. There was a problem that local stress was generated and vertical cracking occurred in the precast block.

[0008]

In the method of constructing a prestressed concrete structure for a tubular structure by stacking precast concrete blocks, when the joint concrete surface becomes uneven, local concentrated stress is generated. Must be a matchcast. Therefore, there are the following problems. (1) Since the precast concrete block is manufactured by the matchcast method, it is necessary to install the structure at the time of constructing the structure in the same positional relationship as that at the time of manufacturing. If this position shifts, the match cast surfaces will not match. (2) The bottom precast concrete block is
Since it is installed on the base concrete, it is very difficult to adjust the installation position and installation height of each divided piece. (3) When the match cast surfaces do not match and a gap is created in the horizontal seam portion, vertical tension causes vertical cracking in the concrete block. (4) Since the precast block construction method aims at labor saving, it is desired that the construction of each piece be a simple method that does not require complicated adjustment.

An object of the present invention is to construct a large tubular structure by stacking match cast concrete blocks, by assembling the lowermost block on the base concrete most appropriately to obtain an upper match. It is an object of the present invention to provide a technique for ensuring that the joint surfaces of cast concrete blocks make correct surface contact so that vertical cracks do not occur in the concrete blocks.

[0010]

According to the present invention, when stacking match cast concrete blocks to construct a prestressed concrete structure, a plurality of steps of concrete blocks at the lower bottom are sewn up and down with a temporarily tightened PC steel rod. A cylindrical shape characterized by creating a reference block with a matchcast concrete surface on the upper surface, mounting and fixing this reference block on the base concrete, and then stacking the matchcast concrete blocks above the reference block. It is a method of constructing a structure.

The method of the present invention is particularly useful when the matchcast concrete block is a vertically divided block. The reference block may be assembled on the upper surface of the base concrete, and a flexible temporary support is arranged on the upper surface of the base concrete, and the reference block is created by combining the plurality of blocks of the lower bottom on the flexible temporary support. It is suitable if it is.

The present construction method is carried out in the following procedure in order to accurately form a reference plane (match cast surface) first. (B) Place the liner plate on the top surface of the base concrete, perform leveling, and place the flexible temporary bearing on it.
The pieces of the bottom concrete block are combined in a circle and placed on a flexible temporary support to form the first stage ring. (B) Install the block immediately above the lowest step at a predetermined position by using the guide key on the first step ring to make the second step ring, and tightly connect the first and second step rings with the steel rod for temporary installation. Form blocks.

Flexible temporary bearings are made of rubber, flexible plastics, sandbags, back jacks, fluid pressure jacks,
One or more equipments selected from the group of air springs and steel springs. These support the vertical load of the concrete block, which is the reference block, and can move in the horizontal direction as well, and they correct misaligned surfaces when combining multiple pieces in a ring shape. It is capable of elastic-plastic deformation. It is possible to use a lump such as rubber or flexible plastics, a sand bag containing sand in a bag, a bag jack in which pressurized fluid is injected into a bag, a fluid pressure operated jack, an air spring, a steel spring, etc. it can.

[0014]

The present invention relates to a method for constructing a tubular structure in which the horizontal joint portion is manufactured by the match cast method, for example, a method for constructing a large diameter PC well. Further, in this precast member, a cylindrical one-stage block is divided into several pieces, and these pieces are stacked alternately while being vertically staggered. (A) Temporarily join several stages of precast blocks including the bottom block to be joined to the base concrete to form a reference block. (B) Non-shrink mortar is applied and fixed on the joint surface between the base concrete and the reference block so that stress can be transmitted uniformly. (C) The upper block is stacked on the match cast surface reproduced on the upper surface of the reference block to construct a tubular structure.

According to the present invention, the height of the bottom concrete block to be placed on the base concrete can be easily adjusted by the flexible temporary support such as expansion and contraction of rubber or the amount of sand in the sandbag. be able to. Then, when the guide block is used to install the concrete block immediately above the lowermost stage, the error in the plane position of the concrete block at the lowermost stage is corrected. This error is absorbed by the shear deformation of the flexible temporary bearing. A tightly rigid reference block can be formed by tightly connecting the blocks of a plurality of stages with a PC steel rod. Then, if an accurate match cast surface is formed, the subsequent construction will be a simple work using only the guide key due to the stacking of the precast concrete blocks of the precast method.

[0016]

[Example] The foundation portion of the pier was constructed by the PC well method using a precast block of the match cast system. The precast block was manufactured by the matchcast method by dividing the horizontal block into 4 pieces by vertical joints. The specifications of the single-stage precast concrete block are as follows.

Outer diameter 9.0 m Inner diameter 7.2 m Wall thickness 0.9 m Height 1.0 m Weight of one block about 60 tons Weight of four divided pieces about 15 tons FIG. 1 shows the precast concrete block of the embodiment. It is a top view. This drawing is for a reference block and is provided with a hole 4 for temporarily fixing PC steel rods. Except for the one for the reference block, there is no hole 4 for temporarily fixing PC steel rod. Further, in FIG. 1, the installation position of the flexible temporary support 21 is shown by hatching, but this is not the block itself.

The precast block 1 has four pieces 2
Is divided into The precast block 1 is manufactured by the matchcast method on the upper and lower surfaces. The connecting PC steel material hole 3 penetrates vertically and is for introducing stress into the structure to form a prestressed structure. The PC steel rod hole 4 for temporary fixing is provided in the lowermost block and the block immediately above it, and is for assembling the reference block. The guide key 5 protrudes to the upper surface, and the guide key recess 7 is provided on the lower surface of the upper precast block.
Insert into and match match cast surface.

12 and 13 show an example of the guide key, which is a guide key 5 made of metal with an anchor 8 provided,
The guide key recess 7 is illustrated. 2 and 3 are explanatory views of the most main part of the present invention.
The bottom block 10a and the bottommost block 10 above
By forming the reference block 10 by b and properly mounting it on the base concrete 11, the match cast blocks above the reference block 10 can be easily stacked. FIG. 3 shows this reference block 10 on which a liner plate 2 is placed on a base concrete 11.
6 and the flexible temporary support 21 are placed and the blocks are arranged and adjusted on the block 10a, 10 with the PC steel rod 12.
The concept of temporarily tightening b to form a reference block is shown. The reference block thus formed is fixed on the base concrete 11 while being adjusted with a jack.
Fig. 4 shows that the base concrete is cast in situ on the cutting edge concrete that has been driven into the ground, the reference block 10 is placed on the base concrete 11, and the precast block 1 of the match cast is stacked above the reference block 10. There is. The reference block 10 is tightly connected with a PC steel rod 12. P to introduce pre-stress into a tubular structure
C steel material 13 is base concrete 11 and reference block 1
0, all of the stacking blocks 1 are provided so as to penetrate vertically.

5 to 11 show the steps of assembling the reference block 10. Figure 5 shows base concrete 1
1 shows a state in which a flexible temporary support 21 such as a rubber or a sandbag is placed on top of which the lowermost block 10a is placed. As for the arrangement of the flexible temporary support 21, as illustrated by hatching in FIG. 1, it is arranged on the part of the dividing surface 6 (longitudinal joint) and the outer peripheral portion of the piece 2. FIG. 11 shows that the flexible temporary bearing 21 is adjusted in height by the liner 26.

Next, as shown in FIG. 5, the lowest block immediately above the block 10b is divided on the lowest block 10a so as to be a division plane (vertical joint).
Place 6 by shifting 1/8 lap. At this time, guide key 5
And the guide key recess 7 together. Blocks 10a, 10
The difference in b is that, for example, as shown by arrow 22, the lowermost block 10a deforms the flexible temporary support 21 to move, and FIG.
Match as shown in. FIG. 7 and FIG. 8 show a situation in which the vertical misalignment 23 of the adjacent block of the lowermost block 10a is corrected.

The reference block 10 thus adjusted on the flexible temporary support 21 is tightly connected and integrated with the PC steel rod 12. The integrated reference block 10 is shown in FIGS.
As shown in FIG.
As shown in FIG. 5, the flexible temporary support 21 is removed to adjust the overall arrangement position, levelness, etc., and then a mold is attached to the periphery to fill the non-shrink mortar and fix it in the regular position.

After the reference block 10 is fixed, FIG.
As shown in (1), the match cast blocks are stacked on top of each other and tightly connected with the PC steel material 13. In the present embodiment, one block is divided into four pieces, but the number of divisions of the pieces may be any number in consideration of size, weight and workability, and the number of steps to be a standard block is two or more. The number of steps may be arbitrary.

The overall construction process of the present invention is as follows. (A) On-site construction of the blade block 11 is performed along with the preparation of the site and the construction of the press-fitting anchor. On the other hand, the factory produces precast concrete blocks by the matchcast method. (B) When the blade block is completed, the precast block will be brought in from the factory. (C) The liner plate 26 is placed at a predetermined position on the upper end surface of the blade mouth block, leveling is performed, and a rubber shoe (flexible temporary bearing) is installed on the liner plate. (D) Four pieces obtained by dividing the bottom block into four are placed on the rubber shavings. (E) On top of that, four pieces of the block immediately above the lowermost stage are stacked using the guide key in a state where the vertical joint surfaces are offset from each other by ⅛. (F) A PC steel rod for temporary fixing is inserted into the lowermost block and the block immediately above it and tensioned to correct the tightness of the two blocks to form a reference block. At this time, the shear deformation of the rubber dregs is used. Of course, the joint surface of the lowermost block and the block immediately above it is the match cast surface. (G) When the reference block is completed, insert a jack between the reference block and the blade block to adjust the level,
Insert a PC steel rod for joining, fill the joint surface between the blade block and the reference block with non-shrink mortar and fix. (H) Since the upper surface of the reference block is a match cast surface, it is possible to smoothly join the blocks stacked on the upper side. After that, stacking of blocks and press-fitting of wells are performed by a known method to complete the foundation work of the pier.

Although this example describes a cylindrical structure, it can be similarly applied to an elliptical, square, rectangular, or parallelogram cylindrical structure.

[0026]

According to the present invention, it is possible to prevent cracks and the like that occur in the precast block due to the mismatching of the joint surfaces between the base concrete and the precast block. Especially in the case of a large-diameter cylindrical structure in which one block is divided into a plurality of parts, the influence of the mismatch of the joint surface is great, but according to the present invention, the reference block is manufactured and mortar or the like is put on the upper surface of the base concrete. Since they are brought into close contact with each other and then the upper matched cast blocks are stacked, the stress is evenly distributed and cracks and the like are completely eliminated.

[Brief description of drawings]

FIG. 1 is a plan view of a precast block.

FIG. 2 is an explanatory diagram of a process of the present invention.

FIG. 3 is an explanatory diagram of a process of the present invention.

FIG. 4 is an explanatory diagram of a process of the present invention.

FIG. 5 is an assembly procedure diagram of the present invention.

FIG. 6 is an assembly procedure diagram of the present invention.

FIG. 7 is an assembly procedure diagram of the present invention.

FIG. 8 is an assembly procedure diagram of the present invention.

FIG. 9 is a conceptual diagram of a jack arrangement according to the present invention.

FIG. 10 is a plan view showing an example of jack arrangement according to the present invention.

FIG. 11 is a detailed view of a joint portion of the present invention.

FIG. 12 is a detailed view of a guide key of the present invention.

FIG. 13 is a detailed view of the guide key of the present invention.

[Explanation of symbols]

 1 Precast Block 2 Piece 3 Connection PC Steel Hole 4 Temporary Fixing PC Steel Rod Hole 5 Guide Key 6 Dividing Surface 7 Guide Key Recess 8 Anchor 10 Reference Block 10a Bottom Block 10b Bottom Direct Block 11 Base Concrete 12 PC Steel bar 13 PC steel 21 Flexible temporary support 22 Arrow 23 Vertical misalignment 24 Jack 25 Arrow 26 Liner plate

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Kinya Kubo 34-1 Marunouchi, Chiyoda-ku, Tokyo Inside PS Corporation

Claims (4)

[Claims] 1. When stacking matchcast concrete blocks to construct a prestressed concrete structure, a plurality of steps of concrete blocks at the lower bottom are sewn together with a temporarily tightened PC steel rod, and the upper surface has a matchcast concrete surface. A method for constructing a tubular structure, characterized in that a reference block is created, the reference block is placed and fixed on a base concrete, and then a match cast concrete block above the reference block is stacked. 2. The method for constructing a tubular structure according to claim 1, wherein the match cast concrete block is a block vertically divided into a plurality of blocks. 3. The tubular structure according to claim 1, wherein a flexible temporary support is arranged on the upper surface of the base concrete, and the reference block is created on the flexible temporary support. How to build. 4. The flexible temporary support is one or more equipments selected from the group consisting of rubber, flexible plastics, sandbags, back jacks, fluid pressure jacks, air springs and steel springs. The method for constructing a tubular structure according to claim 3, wherein.