JPH0563584B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of constructing a sludge concentration storage tank suitably used in small-scale sewage treatment facilities and the like.

[Prior Art] In sewage treatment facilities, sludge concentration and storage tanks are installed as equipment for further concentrating sludge produced in settling tanks. This type of sludge concentration storage tank has a box-shaped structure including a bottom plate, a peripheral wall formed continuously on the bottom plate, and a top wall provided at the upper end of the peripheral wall. Conventional sludge thickening and storage tanks are generally constructed using so-called cast-in-place concrete.

[Problems to be Solved by the Invention] However, in order to construct such a sludge concentration storage tank using cast-on-site concrete, large-scale form work and reinforcing steel work on site are indispensable, which makes the work complicated. Therefore, there are problems in that it is difficult to shorten the construction period and reduce costs, and there are certain limits to quality control.

Therefore, recently, a bottom plate made of precast concrete block, a peripheral wall made of precast concrete blocks placed in multiple stages on this bottom plate, and a precast concrete block made of precast concrete block with a lid attached to the upper end opening of this peripheral wall. A prefabricated sludge thickening storage tank is being considered, which is equipped with a top plate. In such a prefabricated type, in order to facilitate handling during transportation and assembly, each of the peripheral walls is constructed by joining a pair of U-shaped concrete blocks into a housing shape. has also been developed.

When constructing such a conventional prefabricated sludge thickening and storage tank, first, a bottom slab is laid at the bottom of the excavation hole, a peripheral wall is mounted on the bottom slab, and the upper end of the peripheral wall is The lid body is installed as a lid. Each of the peripheral walls is constructed by aligning the U-shaped concrete blocks suspended in the excavation hole in a box-like manner within the excavation hole, and aligning them with the side walls of both of the U-shaped concrete blocks so that they are horizontal. It is made by inserting a prestressed steel rod into the drilled insertion hole, and using the prestressed steel rod to tightly connect both U-shaped concrete blocks.

However, in the conventional method, the two U-shaped concrete blocks are connected by using a PC steel bar with a size corresponding to the length of one side of the peripheral wall body, and fixing nuts at both ends of the PC steel bar. I try to do that. Therefore, it is necessary to secure a space on the side of the peripheral wall for inserting the PC steel rods into the insertion holes of the U-shaped concrete blocks that are butted against each other. Therefore, it is necessary to make the excavation hole very large, and there is a problem in that it takes time and labor to excavate and backfill the ground.

The present invention aims to reliably solve such problems.

[Means for Solving the Problems] In order to achieve the above object, the present invention is formed by laying a bottom slab at the bottom of an excavation hole and joining a pair of U-shaped concrete blocks into a housing. When placing the surrounding wall body on this bottom slab and capping the top slab on the upper end of the surrounding wall body, at least the top and Insertion holes that match each other in the horizontal direction are provided in the middle and lower tiers, and PC steel rods having approximately the same length as the side wall length are inserted into each of the insertion holes in advance, and these U-shaped concrete blocks are After being sequentially introduced into the excavation hole and placed facing each other, the PC steel rods stored in both U-shaped concrete blocks were connected with a coupler, and then both the U-shaped concrete blocks were tightly attached to each other. and then connect it,
It is characterized in that the side walls of the concrete blocks are tightly connected to each other while tension is applied to the middle and lower PC steel bars, and prestress is introduced over the entire surface of the connected side walls. be.

[Function] According to this method of constructing a sludge thickening and storage tank, the peripheral wall, which tends to be particularly noble, is delivered to the site in two parts, that is, in the form of a U-shaped concrete block, and excavation is carried out. Since it can be suspended in the hole, it can be easily transported and can be easily handled during assembly. Furthermore, when transporting U-shaped concrete blocks, they can be loaded onto a transport vehicle with one joint surface of each concrete block in contact with the inner surface of the block, making it possible to transport a large number of blocks at once. It is something that becomes. Furthermore, each of the U-shaped concrete blocks is suspended into the excavated hole with pre-inserted PC steel rods having approximately the same length as the length of the side wall into at least the upper, middle, and lower insertion holes of the U-shaped concrete blocks. , these PC steel bars are connected by a coupler, and tension is applied to both of the PC steel bars to tightly connect both of the U-shaped concrete blocks. There is no need to secure the space required to horizontally insert a long prestressed steel rod with a length equivalent to . Therefore, the size of the excavation hole can be reduced to the necessary minimum size. Further, since prestress is introduced over the entire surface of the connected side wall portions, the strength of the peripheral wall body is increased even though it is formed by connecting two concrete blocks.

[Example] Hereinafter, an example of the present invention will be described with reference to FIGS. 1 to 14.

FIG. 1 is a schematic plan view showing a prefabricated sludge thickening and storage tank according to the present invention, FIG. 2 is a front sectional view thereof, and FIG. 3 is a perspective view thereof. As shown in these drawings, this sludge concentration storage tank includes a bottom plate A made of precast concrete blocks, and surrounding wall bodies B ₁ to _{B 3} made of precast concrete blocks placed on the bottom plate A in multiple stages. and,
The peripheral wall bodies B ₁ to _{B 3} are provided with a top plate C provided with a lid on the upper end opening.

As shown in Fig. 4, the bottom plate A is made by joining a pair of flat concrete blocks 1 and 2 made of reinforced concrete, and the two flat concrete blocks 1 and 2 are joined together using high-tensile bolts 3. It is done using. More specifically, a metal connecting fitting 4 is embedded in the joint end of each of the flat concrete blocks 1 and 2.
As shown in FIG. 5, the connecting fitting 4 includes a thick plate-shaped base plate part 5 and a thin plate-shaped cover part 6 connected to the base plate part 5. Anchor bars 7 are fixed to the plate portion 5. The connecting fitting 4 has the base plate portion 5 exposed on the joint end surfaces 1a and 2a of the flat concrete blocks 1 and 2, and an opening on the upper surface of the concrete blocks 1 and 2. It is buried. A bolt hole 8 is bored in the base plate portion 5, and the two flat concrete blocks 1 and 2 are connected to each other by a high-tensile bolt 3 inserted through the bolt hole 8. After fixing the bolts, the connecting fittings 4 are filled with mortar (not shown).

On the other hand, the surrounding wall bodies _B1 to _B3 are formed by joining a pair of U-shaped concrete blocks 9 and 10 in a housing shape, as shown in FIGS. 6 to 8. U-shaped concrete block 9,
Reference numeral 10 has a prestressed concrete structure in which reinforcing bars (not shown) and PC steel rods 12 are installed, and the two U-shaped concrete blocks 9 and 10 are joined together by the PC steel rods 13 and 12, as shown in FIG. This is done using 14. That is, both U-shaped concrete blocks 9, 10 have side wall portions 9a,
A plurality of through holes 9b, 10b are provided horizontally in the interior of the holder 10a, and the through holes 9b, 10b coincide with each other at the joint surfaces 9c, 10c. Then, with these U-shaped concrete blocks 9 and 10 placed against each other,
It was inserted into the side wall 9a of one block 9.
Threaded portion 13a of PC steel bar 13 and other block 1
The threaded part 14a of the PC steel rod 14 inserted into the side wall part 10a of 0 is connected via a coupler 15,
With tension applied to these PC steel bars 13 and 14,
Threaded portion 13b on the outer end side of the PC steel bars 13, 14,
By fixing nuts 16 ₁ and 16 ₂ to 14b, the side walls 9a and 10a of both blocks 9 and 10 are fixed.
They are tightly joined together. FIG. 9 is an enlarged plan sectional view showing the side wall portions 9a, 10a of both blocks 9, 10, in which 17 is a sealing material made of water-expandable rubber, 18 is a polyurethane resin joint, and 19 is a mortar joint. be.

Further, as shown in FIG. 1, the top plate C is formed by joining a pair of flat concrete blocks 21 and 22 made of reinforced concrete, and the joining of both flat concrete blocks 21 and 22 is as described above. Similar to bottom plate A, high tension bolts 3 are used.

Then, the bottom plate A and the lowermost peripheral wall body B ₁ are connected by the first connecting means 23, and the peripheral wall bodies B ₁ to _{B 3} are tightly joined together using the second connecting member 24, and then The upper peripheral wall body _B3 and the top plate C are connected by a third connecting means 25. The first connecting means 23 is shown in FIG.
As shown in FIG. 2, a pair of insert nuts 27 and 28 are buried adjacent to each other in the outer periphery of the bottom plate A and the lower end outer periphery of the peripheral wall B ₁ . A connecting iron plate 29 is attached to the opening end face, and bolts 31 and 32 passed through the connecting iron plate 29 are screwed into the insert nuts 27 and 28. As shown in FIG. 3, a plurality of sets of the connecting means 23 are provided at required intervals in the lateral direction. Further, as shown in FIGS. 3 and 6, the second connecting means 24 has connecting boxes 33 buried in the inner surfaces of the four corners of each of the peripheral wall bodies B ₁ to B ₃ in an open state, and Within the wall thickness of the four corners of each of the peripheral wall bodies B ₁ to _{B 3} , the inside of the connection box 33 and the peripheral wall body
An insertion hole 36 is provided to connect the upper and lower end surfaces 34 and 35 of B ₁ to B ₃ , and the lower end screw portion 38 of the vertically tightened PC steel bar 37 inserted into the insertion hole 36 is inserted into the lower peripheral wall body B ₁ . Alternatively, position it in the connection box 33 of B ₂ , and position the upper end screw part 39 in the connection box 33 of the upper peripheral wall body B ₂ or B ₃ , and fix the nut 41 to each of the screw parts 36 and 39. By doing so, the vertically adjacent surrounding wall body B ₁ and
B ₂ and B ₂ and B ₃ are respectively connected. Furthermore, as shown in FIG. 3, the third connecting means 25 is provided with recesses 42 on the upper surface of the four corners of the top plate C, and passes through each of these recesses 42 and the insertion holes 36 of the peripheral wall body _B3 . The through holes 36 and the through holes 4 communicate with each other through the holes 43.
Lower end screw part 4 of vertically tightened PC steel rod 44 inserted into 3
5 to the connection box 33 of the uppermost peripheral wall member B ₃
The upper end threaded portion 46 is made to protrude into the recessed portion 42, and both threaded portions 45, 4
6 has a nut 47 fixed thereto. After fixing the nut, the connecting box 33 and the recess 42 are also filled with mortar (not shown).

In addition, FIG. 13 shows the joint part a of the flat concrete blocks 1 and 2 constituting the bottom slab A, and the flat concrete blocks 21 and 22 constituting the top slab C.
joint part e, joint part f between bottom plate A and peripheral wall body _B1 ,
It is an enlarged sectional view showing the joint g between the surrounding wall bodies B ₁ to _{B 3} and the joint h between the peripheral wall body B ₃ and the top plate C, in which 48, 49, 50, 51, and 52 are water-expandable rubber. 54, 55, 56, and 57 are polyurethane resin joints, and 58, 59, and 60 are mortar joints. Further, 62 is a sloped floor made of cast-in-place concrete provided on the bottom slab A, 63 is an opening hole for a manhole cover device drilled in the top slab C, 64, 6
5 is a piping opening.

Next, a method of constructing this sludge concentration storage tank will be explained. First, flat concrete blocks 1, 2, 21 made of brake cast manufactured in a factory etc.
22 and U-shaped concrete blocks 9, 10
will be delivered to the site. At the site, first, the ground 70 is excavated, and a foundation stone 71 is placed at the bottom of the excavated hole 70a.
and pour foundation concrete 72. Then, a mortar 73 is laid on the foundation concrete 72, and the bottom slab A is laid in a predetermined position. Since the bottom plate A is divided into two parts as described above into a pair of flat concrete blocks 1 and 2, these blocks 1 and 2 are joined to high-tensile bolts 3 at predetermined positions. Next, the first stage peripheral wall body _B1 is installed on the bottom plate A. That is, the peripheral wall body B ₁ is also divided into two parts into a pair of U-shaped concrete blocks 9 and 10, and first, the insertion holes 9b are drilled in the side walls 9a and 10a of each of these U-shaped concrete blocks 9 and 10. , 10b, its side wall portions 9a, 10a
PC steel bar 13 with dimensions corresponding to the horizontal length of
14 is inserted in advance. Then, as shown in FIG. 10, these U-shaped concrete blocks 9 and 10 are successively suspended into the excavated hole 70a and placed on the bottom plate A so as to form a substantially rectangular shape. At the joint part b between the blocks 9 and 10, the screw portions 13a and 14a on the inner end sides of the PC steel bars 13 and 14 in the blocks 9 and 10 are connected to each other.
They are connected with a nut-shaped coupler 15, and the connected PC steel rods 13, 14 are tightened with a predetermined tension using a hydraulic jack or the like to fix the nuts. That is, the nut 16 ₁ is screwed onto the threaded portion 13b on the outer end side of one PC steel bar 13, and the nut 161 is screwed onto the threaded portion 13b on the outer end side of one
A nut 16 ₂ is temporarily attached to the threaded portion 14b on the outer end side of the PC steel bar 14. Then, the outer end of the PC steel bar 14 is pulled by a hydraulic jack (not shown), and in this state, the nut ₁₆₂ screwed onto the threaded portion 14b is tightened using a wrench or the like to remove the hydraulic jack. . After that, the bottom plate A
This peripheral wall body _B1 is connected with bolts 31 and 32. Next, the second-stage peripheral wall body B ₂ is assembled in the same manner as the peripheral wall body B ₁ . Thereafter, the first-stage peripheral wall body B ₁ and the second-stage peripheral wall body B ₂ are fastened together using vertically tightened PC steel rods 37 with a predetermined tension. That is, as shown in FIG. 14, both the peripheral wall bodies B ₁ ,
The lower end threaded portion 38 and the upper end threaded portion 39 of the vertically tightened PC steel rod 37 inserted into the insertion hole 36 of B ₂ are respectively positioned in the connecting box 33 of each of the peripheral walls B ₁ and B ₂ , and the lower end threaded portion 38 and upper end screw part 3
A nut 41 is temporarily screwed onto each of the holes 9 through the anchor plate 40. After that, the tension rod 74 inserted into the insertion hole 36 from the upper end side of the second-stage peripheral wall body B ₂ and the upper end screw portion 3 of the vertically tightened PC steel rod 37 are inserted.
9 through a connector 75. Then, the tension rod 74 is pulled upward with a predetermined force by the hydraulic jack 76, and in this state, the nut 41 screwed into the upper end screw portion 39 is tightened using a wrench or the like. After that, this tension bar 74
and the connector 75 is removed, and this peripheral wall body B ₂
Place the third stage peripheral wall body _B3 on top. The third-stage peripheral wall body _B3 is also assembled in the same manner as the second-stage peripheral wall body _B2 , and is tightly connected to the second-stage peripheral wall body _B2 .
After assembling the peripheral wall bodies _B1 to _B3 , the top plate C is set in the upper end opening of the uppermost peripheral wall body _B2 . Regarding the top plate C, a pair of flat concrete blocks 21,
22, these blocks 21 and 22 are joined at predetermined positions with high tension bolts 3. Next, a vertically tightened PC steel rod 44 is inserted from the through hole 43 of this top plate C into the insertion hole 36 of the peripheral wall body _B3 ,
A nut 47 is screwed into the lower end threaded portion 45 of the PC steel rod 44 via the anchor plate 40 in the connection box 33 of the peripheral wall body _B3 , and a nut 47 is screwed into the lower end threaded portion 45 of the PC steel rod 44 through the anchor plate 40.
The anchor plate 4 is attached to the upper end screw portion 46 of the steel rod 44.
0. Screw the nut 47 together. Then, tighten this nut 47 with a wrench, etc., and tighten the top plate C.
is fixed on the surrounding wall _B3 .

As shown in FIG. 3, the peripheral walls B ₁ to _{B 3} are arranged at 90 degrees alternately so that the joints b, c, and d of the U-shaped concrete blocks 9 and 10 do not coincide with each other.
They are arranged one after the other in different directions.
In this embodiment, the joint portion a of the bottom plate A is further
The bottom plate A and the peripheral wall body B ₁ are connected in different directions by 90 degrees from each other so that the bottom plate A and the connecting part b of the lowest peripheral wall body B ₁ do not match, and the joint part b of the top plate C is The top plate C and the circumferential wall B ₃ are arranged consecutively in different directions by 90° so that the portion e and the joint portion d of the uppermost circumferential wall B ₃ do not coincide with each other.

With such a configuration, a finished product can be obtained by combining the bottom plate A, the plurality of peripheral walls B ₁ to B ₃ and the top plate C on site.
This eliminates the need for large-scale formwork and reinforcing work on site, greatly reducing the complexity of on-site work. Further, the bottom plate A, a plurality of peripheral wall bodies B ₁ -
B ₃ and top plate C can be manufactured using mass production methods during construction work, etc., so quality control can be adequately controlled, and sludge concentration storage with high dimensional accuracy and easy cost reduction is possible. It is possible to provide a tank. Moreover, the peripheral wall body B ₁
~By changing the number of stages in _B3 , various tank capacities can be selected, and sludge concentration and storage tanks of various capacities can be selected without changing the design or remanufacturing the formwork, etc. There is the convenience of being able to obtain

Furthermore, according to the construction method of the sludge thickening and storage tank as described above, the surrounding walls _B1 to _B3 , which tend to be particularly bulky, are divided into two parts, that is, in the state of U-shaped concrete blocks 9 and 10. Since it can be carried to the site, transportation can be facilitated. Since these U-shaped concrete blocks 9 and 10 are lighter than those in which the peripheral walls B ₁ to _{B 3} are integrally constituted by a housing-shaped concrete block, they can be moved on site or inside the excavation hole 70a. It is possible to perform the work of lifting and lowering the product relatively easily, and the assembly work can be carried out without requiring large-scale crane equipment or the like. Moreover, since the U-shaped concrete blocks 9, 10 are tightened using PC steel bars 13, 14, the side walls 9a, 1
These two blocks 9 and 10 can be firmly connected with prestress introduced to 0a. Moreover, the side wall portions 9a, 1 of each block 9, 10 are
With PC steel bars 13 and 14 stored in 0a,
Each of the blocks 9 and 10 is introduced into the excavation hole 70a, and both the PC steel rods 13 and
14 are connected by the coupler 15, and then
Both blocks 9 and 10 are made using PC steel rods 13 and 14.
I try to connect them tightly. Therefore, there is no need to secure a space on the sides of the surrounding walls B ₁ and B ₂ for horizontally inserting a PC steel bar corresponding to the length of one side of the surrounding walls B ₁ and B ₂ . It disappears. That is, in this embodiment, the surrounding wall bodies B ₁ , B ₂
It is only necessary that there is a narrow space on the side of the cylinder to accommodate the hydraulic jack. Therefore, the size of the excavated hole 70a can be made much smaller than that of the conventional one, and the labor of excavation and backfilling can be halved.

Note that the number of stacked peripheral wall bodies is of course not limited to that shown in the illustrated example, and can be changed as appropriate depending on the required tank capacity.

Further, the U-shaped concrete block is of course not limited to that of the embodiment described above, and may be of the type shown in FIG. 15, for example.
In other words, this U-shaped concrete block 83
The lengths of one side wall portion 81 and the other side wall portion 82 are different.

[Effects of the Invention] As detailed above, the invention makes the sludge concentration storage tank an assembly type consisting of a bottom plate, a peripheral wall body, and a top plate, thereby eliminating the complexity of on-site work. This makes it possible to shorten the construction period and reduce costs.

Since at least the peripheral wall body is constituted by a pair of U-shaped concrete blocks, problems such as difficulty in transportation and the need for large-scale equipment for transporting concrete blocks at the site can be prevented.

Moreover, since the side walls of the U-shaped concrete blocks are tightened with the PC steel rods with tension applied to them, the side walls of the two U-shaped concrete blocks that are connected are connected. These two blocks can be firmly connected with prestress applied to the entire wall surface.

Moreover, with the prestressed steel rods stored in the side walls of each U-shaped concrete block, each block is introduced into the excavation hole, and both of the prestressed copper rods are connected with a coupler inside the excavation hole. Since both blocks are tightly connected using these PC steel rods, a space is created on the side of the peripheral wall for horizontally inserting a PC steel rod corresponding to the length of one side of the peripheral wall. There is no need to secure any. Therefore, it is possible to reduce the size of the excavated hole to the minimum necessary size, and it is possible to obtain the effect that the labor and time required for excavation and backfilling can be significantly reduced.

[Brief explanation of the drawing]

1 to 14 show an embodiment of the present invention, in which FIG. 1 is a schematic plan view, FIG. 2 is a front sectional view, FIG. 3 is a partially cutaway perspective view, and FIG. 5 is a schematic plan view showing the bottom plate, FIG. 5 is a plan cross-sectional view showing an enlarged joint part of the bottom plate, FIG. 6 is a partially omitted plan cross-sectional view showing the peripheral wall body, and FIG. 7 is a side view of the same. , 8th
Figure 9 is a front view of the same, Figure 9 is an enlarged plan sectional view showing the joint part of the U-shaped concrete blocks, Figure 10 is
The figure is a perspective view to explain the construction order of the surrounding wall body.
Fig. 11 is an enlarged front view showing the connecting part between the bottom plate and the peripheral wall body, Fig. 12 is a sectional view of the same side, Fig. 13 is a sectional view showing the joint part of the bottom plate, the peripheral wall body and the top plate, and Fig. 14 The figure is an explanatory diagram for explaining a method of connecting peripheral wall bodies. FIG. 15 is an explanatory diagram for explaining another embodiment of the present invention. A... Bottom plate, B ₁ to B ₃ ... Surrounding wall body, C... Top plate,
1, 2... Flat concrete block, 1a,
2a... Joint end surface, 3... High tensile strength bolt, 4...
Connecting fittings, 5...Base plate part, 6...Cover part,
7... Anchor bar, 8... Bolt hole, 9, 10...
...U-shaped concrete block, 9a, 10a...
...Side wall part, 9b, 10b...Through hole, 9c, 10
c... Joint surface, 12... PC steel bar, 13, 14...
...PC steel rod, 13a, 13b, 14a, 14b...
...Screw part, 15...Katsupla, 16 ₁ , 16 ₂ ...
Nut, 17... Sealing material, 18... Polyurethane resin joint, 19... Mortar joint, 21, 22
...Flat concrete block, 23...1st
connection means, 24...second connection means, 25...third connection means, 27, 28...insert nuts,
29... Connection iron plate, 31, 32... Bolt, 33
...Connection box, 34...Top end surface, 35...
Lower end surface, 36...insertion hole, 37...vertical tightening PC steel bar,
38... Lower end threaded part, 39... Upper end threaded part, 40
...Anchor plate, 41...Natsuto, 42...
... recess, 43 ... through hole, 44 ... vertically tightened PC steel bar,
45...Lower end threaded part, 46...Upper end threaded part, 47
...Natsuto, 48~52...Seal material, 54~5
7...Polyurethane resin joint, 58, 59, 60
... Mortar joint, 62 ... Slanted floor, 63 ... Opening hole, 64, 65 ... Piping opening, 70 ... Ground, 70a ... Excavation hole, 71 ... Foundation chestnut stone, 72
... Foundation concrete, 73 ... Laying mortar, 7
4... Tension rod, 75... Connector, 76... Hydraulic jack, 81, 82... Side wall portion, 83... U-shaped concrete block.

Claims (1)

[Claims] 1. Laying a bottom slab at the bottom of the excavation hole, placing a peripheral wall formed by joining a pair of U-shaped concrete blocks into a housing on this bottom slab, and placing a top slab on the top end of the peripheral wall. A method of constructing a prefabricated sludge thickening and storage tank with a lid installed, in which at least the upper, middle, and lower levels are horizontally installed at a predetermined pitch within each side wall of a pair of U-shaped concrete blocks to be joined. Insertion holes are provided that match each other in direction, and PC steel rods of approximately the same length as the side wall length are inserted into each of these insertion holes in advance, and each of these U-shaped concrete blocks is sequentially inserted into the excavated hole. The PC steel rods stored in both U-shaped concrete blocks are then connected with a coupler, and then both U-shaped concrete blocks are brought into close contact with each other. A feature is that the side walls of the concrete blocks are tightly connected with tension applied to the connected upper, middle, and lower PC steel bars, and prestress is introduced over the entire surface of the connected side walls. Construction method for a prefabricated sludge thickening storage tank.