JPH0510448B2 - - Google Patents

Description

Detailed Description of the Invention "Field of Industrial Application" The present invention is applicable to materials buried deep underground, such as outer pipes of ultra-deep aeration tanks, large-diameter hollow piles, and structural frames of vertical underground automated warehouses. Concerning construction methods for medium vertical cylindrical structures.

"Problems to be Solved by the Prior Art and the Invention" In recent years, the ultra-deep aeration method shown in Figure 3 has been adopted for the treatment of organic wastewater. In the figure, A is
Outer pipes buried deep underground that make up the ultra-deep aeration tank,
B is a small-diameter inner pipe built into the outer pipe, C is sewage inlet, D is treated water outlet, E is return sewage inlet, F is air for processing to the inner pipe and to the outer pipe. This is a compressor that supplies air for starting circulation.

This ultra-deep aeration method is a biological treatment method, and compared to the conventional activated sludge method, (1) it requires less site area;

(2) High oxygen utilization efficiency.

(3) Possible to treat highly concentrated organic wastewater.

(4) Less sludge generation.

(5) Low odor generation.

It has the following characteristics, and its application fields are wide-ranging, including sewage treatment, domestic wastewater treatment in housing complexes, general industrial wastewater, human waste treatment, gray water facilities, etc., and demand is expected to increase in the future. Further, in this case, since the ultra-deep aeration tank requires an outer pipe with a diameter of 3 to 6 m and a depth of 50 to 150 m to be constructed underground, a construction method that is excellent in terms of quality, economy, etc. is desired.

Conventionally, when constructing the above-mentioned outer pipe underground, as shown in Fig. 4, after underground excavation, a predetermined length of steel pipe b is inserted into the excavated hole a while being connected above ground.
Or, as shown in Figure 5, after underground excavation, a cylindrical PCa unit c...
The method used is to drop them one after another and build them up from the bottom.

However, the former It is uneconomical because it is made of steel.

Durability is low due to progress of corrosion.

In the latter case, it is difficult to ensure the quality of the joint (watertightness, strength) because it is connected underground.

Large diameters require large lifting equipment.

A gap remains between the PCa unit and the excavated soil, making it unstable.

There are drawbacks such as. Furthermore, both have the disadvantage that they are difficult to apply to large diameters.

Therefore, if we were to construct a structure suitable for large diameters using conventional technology, it would probably be as shown in FIG. 6. That is, after drilling a predetermined excavation hole a (), the formwork d and reinforcing bar cage e are inserted and installed in the excavation hole a in a combined state (,
), concrete f is poured in muddy water between formwork d and the hole wall of excavation hole a (), concrete f
After curing, the water inside is drained, the formwork d is dismantled and removed (), and the mold is constructed.

However, even in this case, there is a possibility that the formwork and reinforcing bar cages may be shifted from the center of the excavation hole when installing them. As a result, the structure has thick and thin sections, which poses problems in terms of strength.

Since concrete is placed in muddy water, it is necessary to have a large safety factor for concrete strength, which is uneconomical compared to placing concrete on the ground (in the air).

If the hole wall collapses even slightly during concrete pouring, earth and sand will enter the structure, causing defects in strength, as well as loss of water-tightness and the structure not functioning as intended.

It is almost impossible to repair in the above cases or when jitters are formed on the concrete.

Since it is necessary to leave the formwork underwater until the specified strength is achieved after concrete is poured, special measures must be taken for the material of the formwork, etc.

Scaffolding is required when removing the formwork, but due to the unique nature of the cylindrical structure being buried deep underground, special consideration must be given to the type of scaffolding, how to erect it, how to remove it, etc. .

When transporting removed formwork materials, the narrow gap between the scaffolding and the structure not only makes it difficult to lift with a crane, but also requires workers to be located almost directly below the hoisted material, making the work dangerous. Become.

There are drawbacks such as.

The present invention takes these things into account and improves construction accuracy,
The aim is to provide construction methods that are superior in quality, workability, safety, construction period, cost, and all other aspects.

"Means for Solving the Problems" The present invention involves, after underground excavation, installing a pedestal equipped with a cylindrical form on the ground, and using the form to successively pour-form and harden the concrete frame. is carried into the borehole, and at this time, the weight of the concrete frame is appropriately supported using the buoyancy of the muddy water in the borehole, and after the entire length of the frame is installed in the hole, the gap between the concrete frame and the borehole wall is It is characterized by injecting grout into and hardening it.

``Operation'' The construction described above makes it possible to quickly construct a reinforced concrete frame on site.

"Example" Part 1 FIG. 1 shows an example of the present invention and shows the construction procedure. This is explained in order as follows.

Excavation is performed to a predetermined depth to form an excavated hole 1, a casing 2 is installed on the upper part of the excavated hole to protect the hole wall, and a temporary earthen floor concrete 3 is placed around the excavated hole.

A work platform 4 is installed above the excavation hole 1. This frame is used as a scaffold for reinforcing reinforcement, erecting formwork, pouring concrete, dismantling formwork, and other tasks, and at the same time is used as a device to move the reinforced concrete frame up and down during construction, and to temporarily fix it. It can also be used as a pedestal.

Next, three or more grouting pipes 5 are installed around the excavated hole 1. This grouting pipe is a pipe for grouting the space between the frame and the hole wall with mortar or cement milk after the specified reinforced concrete frame is completed, but it also serves as a guide rail when the frame is sunk one by one. It fulfills the following.

The bottom part of a reinforced concrete frame 6 previously manufactured at another location is inserted into the upper part of the excavated hole 1 and floated on muddy water 7 in the hole. A buoyancy adjustment air bag 8 is attached to the lower surface of the bottom of the frame 6, and when the buoyancy is small compared to the weight of the bottom of the frame, air is sent to the air bag to adjust the buoyancy, and the buoyancy is adjusted to the pedestal 4 for support. Reduce the burden.

With the bottom of the frame 6 temporarily fixed to the frame 4, reinforcing bars 9 are placed on top of the bottom, formwork 10 is erected, and concrete is poured (concrete pouring).
I do. At this stage, as the weight increases, more air is fed into the air bag 8 to increase the buoyancy and maintain the overall weight balance. In addition, in the figure, 4' is a suspended scaffold for work.

After a predetermined retention period of the formwork, the formwork is dismantled. At this time, check the finished condition of the concrete, and if there are any jitters, etc., make sufficient repairs at this point. In addition, treatment of the concrete pouring surface will also be done at this stage.

Next, the frame 6 is lowered to a predetermined position. At this time, let the air out of the air bag 8 to reduce the buoyancy.
If the buoyancy is large even after all the air is removed from the airbag, water is injected 11 into the body 6 to maintain the weight balance. After sinking to a predetermined position, the frame 6 is temporarily fixed to the frame 4 again.

Thereafter, similar operations are repeated to install the frame 6 of a predetermined length into the excavated hole 1.

Finally, the casing 2 is pulled out, and the grout 12 is injected (backfilled) between the hole wall of the excavated hole 1 of the frame 6 through the grout pipes 5... and the grout pipes 5... are successively pulled out. Inject to the top and harden to complete.

Part 2 FIG. 2 shows another embodiment of the present invention. This case is almost the same as the previous example, except that the steps are different and that an appropriate number of PC steel wires 14 for supporting the frame are used for the reinforced concrete frame 6. Therefore, the illustrated steps ``to'', which correspond to the steps ``to'' in the previous example, will be explained.

' A formwork 15 for the sliding form is installed on the pedestal 4, and the formwork 15 is aligned with the rising part of the bottom of the already completed reinforced concrete frame 6. Further, center hole jacks 16 for vertically moving the frame are provided in the frame 4 for inserting and holding PC steel wires 14 for supporting the frame.

' Reinforcement bars 9 are arranged within the formwork 15, concrete is poured, and concrete is poured. At this time, as in the previous example, as the weight increases, more air is supplied to the air bag 8 to balance the weight.

' Next, the formwork 15 is slid.
However, in the general sliding form construction method, the formwork is raised one after another, but in this case, the frame 6 is lowered one after another. This lowering is performed by discharging the air from the air bag 8 and operating the center hole jack 16, and when necessary, water is injected into the frame 6 as in the previous example.

For other processes, precedents apply.

"Effects of the Invention" According to the present invention, (i) The structural frame is made of concrete and no steel pipes are used, so it is economical and there is no fear of corrosion.

(ii) Since all work is done on the ground, construction can be carried out with high precision.

(iii) Since the concrete is formed on the ground, the finished condition can be checked and repairs can be made in some cases.

(iv) Since concrete is placed in the air above the ground, it is possible to adopt a larger allowable compressive stress level in the structural design, compared to when concrete is placed in muddy water, which is economical.

(v) Since the formwork is not left underwater for a long period of time when concrete is poured, it is possible to use a general wooden formwork, and it is economical because it can be reused many times.

(vi) The formwork can be of the sliding form type, in which case there is no need to erect and dismantle the formwork, so the work process can be shortened.

(vii) Since the poured concrete is integrated to form a structural frame, it is possible to construct a frame with high water-stop properties, which is especially useful for using the internal space of vertical underground automated warehouses without water. suitable for the case.

(viii) While constructing the concrete frame, the completed parts are sunk into the excavation hole one by one, using the buoyancy of muddy water, so there is no need for large lifting machines, and there is no need for vertical movement equipment or temporary It is economical because only a small fixing device is required.

(ix) When using buoyancy, if water injection and air bags are used inside the structure, the balance between the weight of the structure and buoyancy can be adjusted sequentially.

(x) By using the grouting pipe as a guide rail for sinking the concrete structure, it is possible to prevent the structure from coming into contact with the hole wall of the excavation hole and destroying the hole wall. This can help ensure accuracy.

(xi) Grout is injected into the gap between the framework installed in the borehole and the hole wall and hardened, resulting in a stable, strong, high-quality, and durable framework that is integrated as a whole and is anchored in the ground. can be built.

(xii) Traditional drawbacks can be wiped out.

It has the following effects and achieves the intended purpose.

[Brief explanation of drawings]

Fig. 1 and Fig. 2 show examples of the present invention, Fig. 1 is a process explanatory diagram of one example, Fig. 2 is a process explanatory diagram of another example, and Fig. 3 is an ultra-deep aeration method. An explanatory diagram of
FIG. 4, FIG. 5, and FIG. 6 are explanatory views showing conventional construction methods, respectively. 1... Excavation hole, 2... Casing, 3... Concrete floor, 4... Frame, 5... Grout pipe, 6... Frame, 7... Mud water, 8... Air bag for buoyancy adjustment, 9... Reinforcement, 10...Formwork, 11
... Water injection, 12 ... Grout, 14 ... PC steel wire,
15...Formwork for sliding form, 16...
...Center hole jack.

Claims (1)

[Claims] 1 After underground excavation, a pedestal equipped with a cylindrical formwork is installed on the ground, and the concrete frame is sequentially poured and formed using the formwork, hardened, and rolled into the excavation hole. After the entire length of the concrete structure is installed in the hole, the weight of the concrete structure is appropriately supported using the buoyancy of muddy water, and grout is injected between the concrete structure and the wall of the borehole and hardened. Construction method for vertical cylindrical structures.