JPH0365447B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a construction method for an underground structure that is suitably used when constructing an underground structure such as a water tank or a basement using box-shaped concrete blocks. It is.

[Prior Art] Recently, it has been considered to manufacture underground structures such as water tanks and basements using box-shaped concrete blocks, which are secondary concrete products. In this case, the construction method is to lay a plurality of box-shaped concrete blocks c, d, and e in an excavated hole b formed in the ground a, as shown in Fig. 11.
The concrete blocks c, d, and e are tightly connected to each other by a plurality of PC steel members f and g, which are inserted through the steel passages formed by mutual communication of the through holes provided in each of these concrete blocks c, d, and e. It is conceivable that after that, the remaining space of the excavated hole b is backfilled with soil.

However, if such a construction method is implemented based on the same concept as when constructing a continuous structure such as a culvert, a problem arises in that the excavated hole b has to be made unnecessarily large. That is,
When tightening box-shaped concrete blocks c, d, and e using PC steel materials f and g, insert the PC steel materials f and g into the through holes drilled in each of these box-shaped concrete blocks c, d, and e. Although it is necessary,
In the conventional type, only one piece of prestressed steel material can be inserted into each through hole. Therefore, when implementing the construction method as described above, after all concrete blocks c, d, and e are accommodated in excavation hole b, at least the through hole of concrete block c that was last accommodated in excavation hole b is The PC steel material f must be inserted from the outer end h side. Therefore, it is necessary to secure a space i for inserting the prestressing steel material f from the outside, and the ground a must be excavated to a corresponding extent. Therefore, the excavation work requires time and labor, and it also causes inconveniences such as having a negative impact on securing a storage space for the excavated soil and backfilling work.

[Problems to be solved by the invention] As mentioned above, the present invention requires inserting the prestressing steel material into the through hole of the concrete block, which necessitates making the excavation hole unnecessarily large, which increases the time required for construction. The aim is to reliably solve the problem of requiring a lot of effort.

[Means for Solving the Problems] In order to achieve the above object, the present invention makes the through hole of the concrete block first accommodated in the excavation hole large, and the through hole is finally accommodated in the excavation hole. The prestressing steel materials to be inserted into the concrete blocks accommodated in the excavated hole are stacked and inserted, and after the last concrete block is accommodated in the excavated hole, the prestressing steel materials are stacked and inserted into the concrete blocks accommodated earlier. One of the concrete blocks is pulled out and inserted into the through hole of the last concrete block stored, and then the concrete blocks are tightened together using these prestressing steel materials.

[Function] According to this construction method, the prestressing steel material to be inserted into the through hole of the box-shaped concrete block to be finally accommodated in the excavated hole is temporarily inserted into the through hole of the concrete block that is accommodated in the excavated hole first. Therefore, it is no longer necessary to insert the prestressing steel material from the outer end into the through hole of the concrete block that was finally accommodated in the excavated hole.
Therefore, the restriction that a space for inserting the prestressing steel material must be provided on the outer end side of the concrete block to be accommodated last is eliminated.
The drilled hole can be made to the minimum necessary size.

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

Example 1 (Figs. 1 to 7) Fig. 1 is a schematic vertical cross-sectional view of a fire prevention water tank that is an underground structure, and Fig. 2 is a cross-sectional view thereof. As shown in these drawings, this fireproof water tank includes a water tank main body 1, a suction tube insertion hole 2 provided in the top plate of the water tank main body 1, and a bottom installation pitch 3 provided in the bottom plate of the water tank main body 1. It is equipped with the following.

The water tank body 1 is made up of three box-shaped concrete blocks 4, 5, and 6 connected together, and lid-shaped concrete blocks 7 and 8 attached to the openings at both ends, and is buried underground. There is.

Further, the suction pipe input hole 2 is formed by drilling an upper opening hole 9 in the top plate 6a of the box-shaped concrete block 6, and inserting a charging pipe 11 into a portion corresponding to the upper opening hole 9 on the upper surface of the top plate 6a. The frame bodies 12 provided at the upper ends of these input pipes 11 are exposed to the ground 13. A manhole cover 14 is attached to the frame 12 so as to be openable and closable.

In addition, each of the concrete blocks 4, 5,
6, 7, and 8 are connected using multiple PC steel barrels.
This is done using PC steel bars 15 and 16. That is, each of the concrete blocks 4, 5,
Through holes 4p, 5p, 6p, 7p, 8p penetrating from one end surface to the other end surface are bored in the four corners of the blocks 6, 7, and 8, and, for example, in the four corners of the middle part of the central concrete block 5, the A recessed portion 17 is provided that communicates with each through hole 5p and opens on the inner surface of the concrete block 5. Further, the outer end surfaces 7a, 8a of each of the concrete blocks 7, 8
, there is a recess 1 communicating with each of the through holes 7p and 8p.
8 is provided. A first steel passage 19 is formed in the four steel passages 19 formed by the mutual communication of the through holes 7p, 4p, and 5p of the concrete blocks 7, 4, and 5.
PC steel rods 15 are inserted through each. Each PC
The steel rod 15 is a steel rod having threaded portions 15m and 15n at both ends, with one threaded portion 15m protruding into the recess 18 of the concrete block 7, and the other threaded portion 15n inserted into the concrete block 5. It is made to protrude into the recessed part 17 of.
An anchor plate 2 is attached to the threaded portion 15m.
A nut 21 is screwed through the thread 0. Also, each through hole 6 of the concrete block 5, 6, 8
The second PC steel rods 16 are respectively inserted into four steel passages 22 formed by mutual communication of P, 7P, and 8P. Each PC steel rod 16 is a steel rod having threaded portions 16m and 16n at both ends, one threaded portion 16m protrudes into the recessed portion 17 of the concrete block 5, and the other threaded portion 16n is inserted into the concrete block 5. Recess 18 of block 8
It protrudes inward. And the screw portion 16m
and the threaded portion 15n of the first PC steel rod 15,
They are connected to each other via a turnbuckle-shaped connector 25 disposed within the recessed portion 17, and a nut 24 is screwed onto the threaded portion 16n via an anchor plate 23. The inner diameters of the through holes in each of the concrete blocks 4, 5, 6, 7, and 8 are large enough to allow two PC steel rods 15, 16 to be inserted therethrough.

Next, a method of constructing this fireproof water tank will be explained with reference to FIG. 1 and FIGS. 4a and 4b. First, an excavated hole 26 is formed in the ground 13, and the concrete blocks 5, 6, and 8 are housed in this excavated hole 26. And these concrete blocks 5,
In the four steel passages 22 formed by the mutual communication of the through holes 5p, 6p, and 8p, the first
The PC steel rod 15 and the second PC steel rod 16 are inserted in a stacked manner. Thereafter, the concrete blocks 4 and 7 are also accommodated in the excavated hole 26. A first PC steel material 15 is inserted into the steel material passage 19 formed by mutual communication of the through holes 4p, 5p, and 7p of the concrete blocks 4, 5, and 7, overlapping the steel material passage 22. bring out.
Then, the outer threaded portion 16 of the second PC steel material 16
At the same time, a nut 24 is screwed onto the PC steel bar 16 through the anchor plate 23, and an inner threaded part 16m of this PC steel bar 16 and an inner threaded part 15n of the first PC steel bar 15 are screwed into the recessed part 17. Connector 25 placed in
Connect via. Next, an anchor plate 2 is attached to the outer threaded portion 15m of the first PC steel rod 15.
The nut 21 is provisionally screwed together through the threaded portion 15m, and the tip of the tension rod 28 is connected to the tip of the threaded portion 15m via the connector 27. A hydraulic jack 29 supports the base end 28a of the tension rod 28 on the end surface 7a of the concrete block 7.
tension is applied to both the PC steel bars 15 and 16 by pulling the PC steel bars 15 and 16. In this state, tighten the nuts 21 and connect each concrete block 4, 5, 6,
Tighten and connect 7 and 8. Thereafter, the hydraulic jack 29 and the tension rod 28 are removed, and the steel passages 19, 22, the recess 17, and the recess 18 are filled with mortar (not shown). Thereafter, the remaining space of the excavated hole 26 is backfilled with soil to complete the construction.

According to such a construction method, the PC steel rod 15, which is to be inserted into the through holes 4p and 7p of the concrete blocks 4 and 7 to be finally accommodated in the excavated hole 26, is first accommodated in the excavated hole 26. It can be pulled out from through holes 5p, 6p, 8p of concrete blocks 5, 6, 8. Therefore, there is no need to provide a space in advance outside the concrete block 7 for inserting the PC steel rod 15. Therefore, the excavation hole 26 does not need to be pre-dug to a large extent to accommodate the space, and the labor and time required for excavation can be greatly saved, and the temporary disposal of the excavated soil is also facilitated. You can get the effect of

Example 2 (Figures 8 to 10) This example differs from Example 1 in the manner in which the PC steel bar is used, but the same or corresponding parts will be described with the same reference numerals. omitted.

In this second embodiment, for example, each of the through holes 5 are formed in the four corners of the middle part of the central concrete block 5.
A metal connecting box 31 communicating with the concrete block 5 and opening on the inner surface of the concrete block 5 is buried therein. Further, as in the first embodiment, a recess 18 is provided on the outer end surface of each concrete block 7, 8 and communicates with each through hole 7p, 8p. Then, the first PC steel rods 15 are inserted into the four steel passages 19 formed by the mutual communication of the through holes 7p, 4p, and 5p of the concrete blocks 7, 4, and 5, and each of these PC steel rods is The inner threaded portion 15n of the concrete block 5 is projected into each connection box 31 of the concrete block 5, and the outer threaded portion 15m is inserted into the concrete block 7.
It is made to protrude into the recessed part 18 of. An anchor plate 2 is attached to each of these threaded portions 15m and 15n.
Nuts 21 and 33 are screwed through nuts 0 and 23. In addition, the concrete blocks 5, 6, 8
The second PC steel rods 16 are inserted into the four steel passages 22 formed by the mutual communication of the through holes 5p, 6p, and 8p, and each of these PC steel rods 16
The inner threaded part 16m of the concrete block 5 projects into the connecting box 31 of the concrete block 5, and the outer threaded part 16n projects into the recessed part 18 of the concrete block 8. Nuts 24 and 35 are screwed onto these threaded portions 16m and 16n via anchor plates 23 and 34, respectively.

Next, a method of constructing this fireproof water tank will be explained with reference to FIG. 8 and FIGS. 9a and 9b. First, an excavated hole 26 is formed in the ground, and the concrete blocks 5, 6, and 8 are housed in this excavated hole 26. The first PC steel rod 15 and the second PC steel rod are inserted into the four steel passages 22 formed by the mutual communication of the through holes 5p, 6p, and 8p of these concrete blocks 5, 6, and 8. 16 and insert them one on top of the other. Thereafter, the concrete blocks 4 and 7 are also accommodated in the excavated hole 26. And each through hole 4 of the concrete block 4, 5, 7
The first PC steel material 15, which has been inserted into the steel material path 22 and overlapped with the steel material path 22, is pulled out into the steel material path 19 formed by the mutual communication of P, 5p, and 7p. and,
A nut 24 is screwed onto the outer threaded part 16n of the second PC steel material 16 via the anchor plate 23, and a nut 35 is provisionally threaded into the inner threaded part 16m via the anchor plate 34. Furthermore, the inner threaded portion 16 of this second PC steel rod 16
m and the inner threaded portion 15 of the first PC steel rod 15
n and the connector 25 in the connection box 31.
Connect via. After that, a tension rod 28 is connected to the outer threaded portion 15m of the first PC steel bar 15 via a connector 27, and a hydraulic jack 29 is installed in which the tension rod 28 is supported on the end surface 7a of the concrete block 7. By towing the said
Tension is applied to the PC steel bars 15 and 16. In this state, the concrete blocks 5, 6, and 8 are tightly connected by tightening the nut 35 temporarily screwed onto the threaded portion 16m of the second PC steel rod 16. Next, after stopping the traction by the hydraulic jack 29, the connector 25 in the connecting box 31 is removed, and the anchor plates 20, 3 are attached to the threaded portions 15m, 15n of the first PC steel bar 15.
Screw the nuts 21 and 33 through 2. Then, the hydraulic jack 29 applies tension to the first PC steel rod 15 again. In this state,
By tightening the nut 21 temporarily screwed onto the outer threaded portion 15m of this first PC steel rod 15,
The concrete blocks 4, 5, and 7 are tightly connected. Then, the hydraulic jack 29 and the tension rod 28 are removed, and then the steel passages 19, 2
2, the connection box 31, and the recess 18 are filled with mortar. After that, the drilling hole 2
Construction is completed by backfilling the remaining space in No. 6 with soil.

In this case as well, the through holes 4 of the concrete blocks 4 and 7 to be accommodated in the excavated hole 26 are finally
Concrete blocks 5, 6, with the PC steel rods 15 to be inserted into the holes 26, 15 and 15, which are inserted into the holes 26,
8 through the through holes 5p, 6p, and 8p. Therefore, there is no need to provide a space in advance outside the concrete block 7 for inserting the PC steel rod.

Note that the PC steel material may not be in the form of a rod but may be in the form of a strand. That is, in the case of strands as well, since it is not possible to bend them to an extreme degree, the construction method according to the present invention can provide certain effects.

Furthermore, it goes without saying that the manner in which the concrete blocks are tightened with the prestressed steel material is not limited to those of the first and second embodiments. For example, the first prestressed steel bar 15 and the second prestressed steel Alternatively, the nuts 21 and 24 may be tightened by applying tension to the rods 16 by the hydraulic jacks 29, respectively.

Further, the number of box-shaped concrete blocks to be connected is not limited to that of the illustrated embodiment, and various modifications can be made without departing from the spirit of the present invention, such as using four, for example.

Furthermore, it goes without saying that the cross-sectional shape of the steel passage is not limited to the circular shape described above, and can be modified in various ways, such as an elliptical shape, for example.

Moreover, the underground structure is of course not limited to a fire prevention water tank, and may be a basement or the like.

[Effects of the Invention] As described in detail above, the present invention inserts an extra prestressing steel material into the through hole of the concrete block that is accommodated first in the excavated hole, and then inserts the last concrete block into the excavated hole. After housing, one side of the PC steel material is pulled out and inserted into the through hole of the concrete block that was housed last, so that the PC steel is placed outside of the concrete block.
There is no need to prepare the necessary space to insert the steel material. Therefore, it is possible to reliably eliminate the inconvenience that excavation work requires time and labor and has a negative impact on securing a storage space for excavated soil and backfilling work. Therefore, it is possible to provide an excellent method for constructing an underground structure, which allows construction to be carried out relatively freely in any location.

[Brief explanation of drawings]

1 to 7 show one embodiment of the present invention, FIG. 1 is a vertical sectional view showing the entire underground structure, FIG. 2 is a sectional view taken along the line - in FIG.
Figures 4a and 4b are explanatory diagrams for explaining the construction order, Figure 5 is an enlarged explanatory diagram showing the parts in Figure 4 in detail, and Figure 6 is the part in Figure 4. Enlarged explanatory diagram showing details, No. 7
The figure is an enlarged explanatory view showing in detail the part in FIG. 4. 8 to 10 show other embodiments of the present invention, FIG. 8 is a longitudinal sectional view showing the entire underground structure, FIGS. 9a and 9b are explanatory views for explaining the construction order, and FIG. FIG. 10 is an enlarged explanatory diagram showing the portion in FIG. 8 in detail. FIG. 11 is an explanatory diagram for explaining a conventional example. a...Ground, b...Drilled hole, c, d, e...Box-shaped concrete block, f, g...PC steel material,
h...Outer end, i...Space, 1...Aquarium body, 2...Suction pipe inlet, 3...Bottom pit, 4,
5, 6...Box-shaped concrete block, 4p, 5
p, 6p... through hole, 7, 8... lid-shaped concrete block, 7a, 8a... end surface, 7p, 8p...
...Through hole, 9...Top opening hole, 11...Input pipe,
12... Frame, 13... Ground, 14... Manhole cover, 15, 16... PC steel, 15m, 15n,
16m, 16n...Thread part, 17...Concave part, 1
8... Recess, 19... Steel passage, 20... Anchor plate, 21... Nut, 22... Steel passage, 23... Anchor plate, 24... Nut, 25... Connector, 26... Drilled hole , 27...
Connector, 28...Tension rod, 28a...Proximal end, 2
9...Hydraulic jack, 31...Connection box,
32... Anchor plate, 33... Natsu, 3
4...Anchor plate, 35...Natsuto.

Claims (1)

[Claims] 1 A plurality of box-shaped concrete blocks are housed in an excavated hole formed in the ground, and each of the concrete blocks is constructed by a plurality of prestressing steel members inserted into steel passages formed by mutual communication of through holes provided in each of these concrete blocks. In the method for constructing an underground structure in which concrete blocks are tightly connected to each other and the remaining space of the excavated hole is then backfilled with soil, the through-hole of the concrete block first accommodated in the excavated hole is made large; Into the through hole, the prestressing steel material to be inserted into the concrete block to be accommodated in the excavated hole last is inserted in layers, and after the last concrete block is accommodated in the excavated hole, the prestressed steel material is inserted into the previously accommodated concrete block. One of the prestressing steel materials that had been inserted in stacks was pulled out and inserted into the through hole of the last concrete block, and then these prestressing steel materials were used to tighten each concrete block together. Features: Construction method for underground structures.