JPH0436951B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a construction method for a precast prestressed concrete tank used for an aquarium or the like.

[Problem to be solved by the invention]

Generally, large concrete PC tanks have a structure in which a formwork is built on site, a frame is created using cast-in-place concrete, and prestress is introduced by placing prestressing steel wires around the circumference of the frame. The construction requires a considerable period of time, and a considerable amount of effort is required to ensure quality. It is also known that cylindrical structures such as water tank silos are constructed by assembling blocks or segments vertically and horizontally and inserting prestressed steel wires to introduce prestress. It cannot be applied immediately due to watertightness, strength, etc.

This invention was developed to solve the above-mentioned conventional problems.

[Structure of the invention]

The gist of this invention is to create a bottom slab by on-site construction, lay an elastic board on the periphery of the bottom slab, and then install flat precast concrete segments that will become side walls and precast concrete segments for the pilaster part. Assemble it vertically on an elastic plate so that it forms a polygon when viewed from above,
Narrower on the medial side at the longitudinal junction of each segment;
A gap with a wide outer side is formed, an auxiliary sheath is placed in the outer gap, an elastic sealant is filled in the inner gap, mortar is placed in the outer gap, and after the mortar reaches a predetermined strength. Tension the circumferential PC steel material inserted into the segment and sheath,
The PC steel material is fixed to the precast concrete segment of the pilaster part, and then buried and fixed with anchor fittings protruding from the lower end of the side wall, anchor fittings protruding from the bottom plate, and cast-in-place concrete placed in the corners of the side wall. This is a construction method for precast PC tanks that is characterized by:

〔Example〕

In Figures 1 and 2, this tank is bottom plate A.
and side wall B. Side wall B is segment 1 of precast concrete forming the general part.
It consists of precast concrete pilaster section segment 2 to which the circumferential prestressing steel material is tension-fixed.

Each of the segments 1 and 2 described above has a flat plate shape, and the side wall B is assembled so as to form a polygon when viewed from above.

The outline of the assembly of each segment described above is as shown in Figures 3 and 4. First, the bottom plate A is constructed on-site, and then the support C is assembled inside the tank. The pilaster part segments 2 are established vertically on the bottom plate A at predetermined intervals, supported by the shoring C, and the prestressing steel members 3 are sequentially fixed under tension in the vertical direction, and each segment 1,
Hopper D is placed in the vertical gap of 2, that is, the vertical joint.
After the mortar has reached a predetermined strength, the PC steel material 4 in the circumferential direction is filled with mortar.
tension and fix it to the pilaster segment 2.

Further details of each part will be explained below.

As shown in the figure, there are two types of segments 1: vertically long ones and horizontally long ones, which are used appropriately depending on the depth, size, etc. of the tank. , 6 are formed by embedding a sheath or the like.

Moreover, a prestressed steel bar is used as the prestressed steel material 3 in the vertical direction, and is connected by a coupler 7 in a groove formed in the middle of the segment 1. Also, in the circumferential direction
A strand is used as the PC steel material 4, and is tension-fixed by penetrating the pilaster segment 2 in a crosswise manner.

The joint portion between the bottom plate A and the segment 1 and the pilaster portion segment 2, that is, the support structure between the bottom plate A and the side wall B is substantially a hinge structure. When the hinge structure is adopted, the bending moment due to the water pressure generated at the lower end of the side wall is small, and the prestress in the circumferential direction acts effectively. The supporting structure is as shown in Fig. 14, and the adjustment mortar 8 is attached to the periphery of the bottom plate A.
An elastic plate, for example, hard rubber 9, is laid on top of this, and a side wall is installed on top of it, and the shearing force that is maximum at the lower end of the side wall is transmitted to the bottom plate A via an anchor bolt 10 as an anchor fitting. It is.

Further, a connecting reinforcing bar 11 is provided as an anchor fitting on the outer periphery of the lower end of the side wall B, and cast-in-place concrete 12 is placed at the corner of the bottom slab A and the side wall B, and the anchor bolt 10 and the connecting reinforcing bar 11 are buried. and become established. Note that 13 indicates an elastic sealing material.

The vertical connection portion of each segment 1 is made by providing unevenness on the upper and lower end surfaces of the segment 1 and abutting against each other in an engaged state, and bonding the end surfaces with an adhesive if necessary. Further, a waterproof rubber material 14 is interposed between the end faces, and an elastic sealing material 15 is filled on the inner surface of the tank.

FIG. 7 shows details of an embodiment of the circumferential connection part of each segment 1, that is, the vertical joint, in which a gap is formed at the joint part between each segment, narrow on the inside and wide on the outside; An auxiliary sheath 18 is placed in the gap, and an elastic sealing material 15 is placed in the inner gap.
A mortar 17 such as expanded mortar is placed in the outer gap. After the mortar 17 reaches a predetermined strength, each segment 1, 2 and sheath 6,
PC steel material 4 inserted in the same direction into the auxiliary sheath 18
make me nervous.

15 and 16 show other embodiments of segment assembly. In this case, an embodiment is shown in which a plurality of segments are assembled into a block shape on a workbench 19 having an inclined surface, and then the block-shaped segments are erected by a crane or the like.

〔Effect of the invention〕

This invention has the above-mentioned configuration, and the side walls are all assembled from flat plate-shaped precast concrete segments, and the vertical joint gap is widened on the outside and narrowed on the inside, so that it forms a polygon when viewed in plan. Because it is assembled into segments, it is possible to accommodate changes in the overall diameter of the tank to some extent with segments of fixed dimensions, making it easier to manufacture,
Construction is easy. In addition, since concrete is poured with an auxiliary sheath placed in the gap between joints, there is no problem in inserting and tensioning the PC steel wire. In addition, since an elastic plate is laid around the periphery of the bottom plate and the side wall is assembled on top of it, the joint between the bottom plate and the side wall essentially becomes a hinge structure, making it easy to introduce prestress, and allowing the water pressure generated at the lower end of the side wall to be easily applied. Bending moment can be reduced.

Furthermore, by burying the anchor fittings protruding from the bottom slab and side walls in the cast-in-place concrete at the corners, it is possible to cope with shearing forces.

[Brief explanation of drawings]

1 and 2 are a side view and a cross-sectional view showing an overview of the tank according to the present invention, FIGS. 3 and 4 are exploded side views showing an overview of assembly and construction, and FIGS. 5 and 6 are
The figures are a vertical cross-sectional view and a cross-sectional view showing the arrangement and fixation state of the prestressing steel, Figure 7 is a cross-sectional view of the vertical joint of the segments, Figures 8, 9, 10, and 11. 12 and 13 are longitudinal sectional views of the segment and the upper and lower joints, FIG. 14 is a longitudinal sectional view of the side wall support, 15, 16, and FIG. 17 is a perspective view and an elevation view showing an overview of the assembly process. A... Bottom slab, B... Side wall, C... Shoring, D...
...hopper, 1... segment, 2... pilaster section segment, 3... vertical PC steel material, 4...
...Circumferential direction PC steel material, 5, 6...Insertion hole, 7...
Cup puller, 8...Adjustment mortar, 9...Hard rubber, 10...Anchor bolt, 14...Water stop rubber, 15...Elastic sealing material, 17...Expansion mortar, 18...Auxiliary sheath, 19...Work The stand.

Claims (1)

[Claims] 1. A bottom slab is constructed on-site, an elastic board is laid on the periphery of the bottom slab, and then flat precast concrete segments that will become side walls and precast concrete segments for pilasters are laid vertically on the elastic board. Assembled to form a polygon when viewed from above, a gap is formed at the longitudinal joint of each segment with a narrow inner side and a wider outer side, an auxiliary sheath is placed in the outer gap, and an elastic sealing material is placed in the inner gap. Fill the outer gap with mortar, and after the mortar reaches a predetermined strength, tension the circumferential pre-cast steel material inserted into the segment and sheath, and add the pre-cast concrete material to the pilaster section. established in the segment,
A method of constructing a precast PC tank, which is characterized in that the precast PC tank is then buried and fixed using anchor fittings protruding from the outside of the lower end of the side wall, anchor fittings protruding from the bottom plate, and cast-in-place concrete poured into the corners of the side wall.