JPH0262652B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention utilizes underground underground structures such as vertical piles, in particular, using the pile construction method and prefabricated products for underground structures that require subsequent on-site construction. Concerning construction methods and prefabricated underground structures used therein.

[Conventional technology]

Underground structures such as vertical pile piers are often buried using the submerged box method.

Here, the submerged box construction method refers to a construction method in which the structure itself is built above ground, or prefabricated products are assembled into a predetermined structure and then buried underground.

[Problem to be solved by the invention]

By the way, depending on the soil quality of the excavated ground, it is necessary to protect the surrounding ground by using missing boards, corrugated walls, or continuous wall construction methods, etc., and to prevent loosening and water leakage around the board, due to safety concerns. Measures are required. These countermeasures require construction such as ground improvement, drainage pots, well points, and underpinning as the construction progresses, which creates problems in terms of economy, safety, speed, etc.

In addition, the foundation structure after the building frame is buried must be a reinforced concrete structure that is constructed on-site afterwards, and spring water treatment during the construction of the reinforced concrete bottom plate after burial is usually carried out inside the underground structure below the groundwater table. As a result, concrete cannot be poured under sufficient supervision, resulting in concrete that lacks watertightness, leaving the risk of defects such as water leakage. If this construction is used in conjunction with the sheet pile construction method, etc., a site area that includes the main frame and the required width of the sheet piles, center beams, etc. will be required, and in addition, when construction is carried out on the street, reconstruction boards will be temporarily placed for traffic reasons. It is necessary to proceed with the construction, and since using reconstruction boards on the road will hinder smooth traffic flow, it is requested that the construction be completed in a short time.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a prefabricated underground structure that overcomes the above-mentioned drawbacks and allows for safe, economical, and quick work.

[Means to solve the problem]

The present invention aims to achieve the above-mentioned object, and its means include a prefabricated block having communicating holes formed in at least four corners, and a fixing fitting embedded in the communicating hole communicating with the communicating hole of the prefabricated block. inserted into at least two or more of the communication holes of the side blocks in the stacked state, the lower end is screwed to the fixing metal fitting, and the upper end protrudes from the uppermost side block. The PC steel rod is inserted into the communication hole of the side block in the stacked state, and the lower end is inserted into the communication hole in which the side block is not inserted, and the lower end is connected to the fixing metal fitting. The gist of this is a prefabricated underground structure comprising a steel pipe which is screwed together with a steel pipe whose upper end protrudes from the uppermost block and is used as a drainage pipe and a grout pipe.

[Embodiments of the invention]

Hereinafter, the first and second embodiments will be explained with reference to the drawings.
In the figure, 1 to 4 are side blocks made of prefabricated concrete having a rectangular or polygonal planar shape, and upper blocks 2, 3, and 4 are sequentially stacked on top of the lowest block 1.

A floor slab block 5 having a manhole entrance/exit hole 5a is mounted on the uppermost block 4.

6 will be made of low slab concrete and will be constructed on site after the lowest block 1 has subsided using the submerged box construction method.

In addition, the lowest side block 1 has a step on the outer wall surface compared to the other side blocks 2 to 4 in order to ease the frictional resistance caused by the soil around the side block and facilitate settlement during subsidence by the submerged box construction method. This aims to reduce the frictional force between the front and side blocks.

In addition, step portions 1a, 2a, 3a are formed around the entire circumference on each horizontal joint surface of each of the side blocks 1 to 4, and a sponge 8 impregnated with plastic rubber 7 or epoxy resin is placed on these steps. The aim is to create an adhesive effect between the blocks and prevent water leakage.

Further, vertical communication holes 1b, 2b, 3b, 4 are provided in at least four corners of each side block 2 to 4 and the floor slab block 5.
b, 5b are formed, and an external through hole 1c having an opening on the outside at a point near the lowest part is formed in the lowest side block 1, and fixing metal fittings 9, 9' are formed in this external through hole 1c. There is.

In addition, the fixing metal fittings 9, 9' are the fourth,
There are two types shown in Fig. 5, in which a T-shaped one is buried in concrete in Fig. 4, and a box-shaped one in Fig. 5 is buried in concrete.

Next, the construction method (in the case of an underground manhole in this example) will be explained.

First, on the ground, the side blocks 1 to 4 are sequentially stacked with the plastic rubber 7 or sponge 8 interposed therebetween as described above. At this time, each communication hole 1b of each side block 1 to 4
-4b are each communicated as one hole.

Next, the steel pipe 1 is inserted from each communication hole 4b of the uppermost block 4.
0 to the fixing fitting 9, and the lower end threaded portion of the steel pipe 10 is screwed into the fixing fitting 9, and the plug 20 is screwed into the inside of the fixing fitting 9.

In addition, the PC steel rod 10' is passed through the remaining communication hole up to the fixing fitting 9', the nut 11 is screwed into the lower end threaded part of the PC steel rod 10', and then a fixing agent 12 such as mortar is applied. Tightly seal the container to maintain sufficient watertightness.

Then, a filter 13 is attached from the outside to a portion opened to the outside of the external passage hole 1c communicating with the fixing metal fitting 9 or the external passage hole 1c communicating from the fixing metal fitting 9' via the socket 22. After all of the side blocks are stacked, the steel pipe 10 and PC steel bar 10' protruding from the communication hole 4b of the uppermost side block 4 are temporarily tightened and fixed with nuts 14, whereby the side block 1
- Integrate 4. In addition, a nut 14 is attached to the steel pipe 10.
When screwing together, the fixing plate 19 is also fixed integrally.

Next, insert a center hole hydraulic jack into the upper part of the PC steel bar 10', tension the PC steel bar 10' within the allowable stress range of the steel pipe tensile strength, and tighten the nut 14.
Make the final tightening.

The fixing plate 19, which is tightened to the steel pipe 10 with nuts 14, has a grout hole 21 and serves both of the effect of filling the surroundings of the steel pipe 10 and the role of fixing the steel pipe 10. Incidentally, it is also possible to tighten a nut 21' in the grout hole (Fig. 4). Further, 12' shown in FIG. 5 is also a grout hole, and the grout hole 12' is filled with mortar, into which mortar is injected through a thin flexible vinyl or rubber tube.

Next, shear reinforcing bars are placed on the lowermost mass 1 and concrete work is performed.Here,
If the surrounding ground loosens or springs water, it will not be possible to pour concrete with sufficient watertightness.

Therefore, in the present invention, a method is adopted in which a vacuum pump is connected to the protruding end of the above-described steel pipe 10 to suck spring water. A filter 13 acts on this suction and drainage to prevent the inside of the steel pipe 10 from becoming clogged. This allows reinforcing and concreting to be carried out under conditions similar to normal surface work, even in areas below groundwater, thus increasing the accuracy, quality, efficiency and safety of a given structure. Can be done.

Then, after completing the concreting of the bottom slab by the above-mentioned method and achieving a predetermined strength, the protruding tip of the steel pipe 10 used as the suction water pipe is removed from the vacuum pump, and this time it is connected to the grout pump. Then, inject grout using mortar milk, etc. At this time, the filter 13 is discharged from the external hole 1c by the pressure of the grout, and the grout flows out around the opening of the external hole 1c.

Therefore, the loosening of the ground around the lowermost side block 1 and the bottom of the bottom slab can be prepaced by grouting, improving the surroundings of the ground and sufficiently preventing ground subsidence.

Next, the slab block 5 is placed on top of the uppermost block 4, and screwed and fixed with nuts using the steel pipe 10. The floor slab mass 5 is provided with a communication hole corresponding to the lower side mass, and after the above-mentioned fixation, end treatment is performed using a corrosion-resistant cap.

The top of the bottom slab usually contacts the ground with an entrance ring. If the underground structure is a shaft or the like, it is possible to start work on the side hole or propulsion pipe as is without the need for horizontal members such as center beams or uprights. After the work is completed, the structure itself can be used as a manhole frame, so the work can be completed with the installation of the slab mass and manhole ring.

In addition, if the purpose of construction of the side block is a propulsion shaft, suction and drainage can be continued even during the construction of the propulsion pipe. The grouting performed later contributes to preventing ground subsidence or immobility settlement around the propulsion pipe.

〔Effect of the invention〕

As described above, the present invention inserts and fixes the steel pipes and PC steel bars into the communicating holes of the stacked side blocks, so in particular,
The PC steel rods can be used to integrate the side masses, and the steel pipes can be used to drain underground spring water, so the bottom slab concrete work as a pressure plate can be done reliably and quickly. After the work is completed, grout can be injected through the steel pipes to improve the ground, which shortens the work time and minimizes the work site area, making the work easier than draining and grouting as separate works. , can significantly improve traffic confusion on the road.

In this example, for a 40 cubic meter underground manhole, the slab was completed within 48 hours from the start of the frame installation, which is an extremely rapid effect compared to open excavation work, which normally takes one to two months. has.

[Brief explanation of drawings]

The figures show an embodiment according to the present invention, in which Fig. 1 is a plan view, Fig. 2 is a sectional view taken along the - line in the same as above, Fig. 3 is a sectional view taken along - line in Fig. 1, and Figs. 4 and 5 are fixing metal fittings. An enlarged view of the part, FIG. 6 is a judgment plan showing the construction state. 1 to 4... Side mass, 1b, 2b, 3b, 4b, 5
b...Communication hole, 9,9'...Fixing metal fitting, 10...
Steel pipe, 10'...PC steel bar.

Claims (1)

[Scope of Claims] 1. A prefab side block having communication holes formed in at least four corners, and a lowermost side block in which a fixing metal fitting is embedded in a communication hole communicating with the communication hole of the prefab side block, in a stacked state. It is inserted into at least two or more of the communication holes of the side block, the lower end is screwed to the fixing metal fitting, the upper end is protruded from the uppermost side block, and a nut is screwed together to integrate the side block. become
PC steel rod and the above communication hole of the side block in the stacked state
A steel pipe that is inserted into the communication hole in which the PC steel rod is not inserted, whose lower end is screwed to the fixing fitting, and whose upper end protrudes from the uppermost block and is used as a drain pipe and a grout pipe. A prefabricated underground structure characterized by: