JP2891431B2 - Subway reinforced concrete wall construction method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a subway reinforced concrete continuous wall construction method used as a retaining wall or the like of a shield machine start / reach shaft.

[Background of the Invention]

This type of subway reinforced concrete continuous wall is formed by excavating the ground with an excavator to form a ditch, laying a steel cage in the ditch, and then pouring concrete from the lower part of the ditch. Is done. When excavating the vertical ditch with an excavator, a stabilizing liquid is injected into the vertical ditch to balance the earth pressure or groundwater pressure of the vertical ditch peripheral wall with the liquid pressure of the stable liquid, thereby causing collapse of the vertical ditch peripheral wall. To prevent.

The ground inside the subway reinforced concrete continuous wall thus formed may be excavated to form a shaft, and an underground cave may be connected to the shaft. Then, a shield machine is started to dig an underground cave, or a shield machine that has digged an underground cave to reach the entrance.

[Conventional technology]

Conventionally, a pit was opened by cutting the reinforced cage of the reinforced concrete continuous wall and cutting the concrete to perform a mirror-cutting work, and a shield machine was started from the pit or reached to the pit. At this time, at the time of opening of the pit, to prevent the collapse of soil and groundwater from the ground side,
Prior to the opening of the pit, the ground was stabilized by applying a freezing treatment or a chemical injection treatment to the ground near the portion corresponding to the pit of the reinforced concrete continuous wall.

[Problems to be solved by the invention]

However, in the above-mentioned freezing process, although the ground on the ground side can be stabilized, the construction days are long, and the cost for freezing is considerably high. Also, in the chemical solution injection process, the ground stabilization is not uniform, the reliability is low, and there is a risk of flooding and ground collapse. Furthermore, the above-mentioned mirror-cutting work involves a decrease in work efficiency and a deterioration in the work environment, and there are many problems in safe construction management. These problems become more serious with the use of a shield method with a large depth and a large diameter. It has become something.

[Means for solving the problem]

According to the present invention, as a means for solving the above-mentioned conventional problems, a step 1 of injecting a stabilizing liquid (2) and excavating the ground with an excavator to form a vertical groove (1) 1 Inside the shield machine (16)
5) Reinforcing cage (3) with built-in formwork (4) is built in the corresponding part, and the formwork (4) is filled with muddy water (10) dispersed with beads (9) having a specific gravity of 1.0 to 1.2. Step 2 Pour concrete from the lower part of the vertical groove (1) Step 3 Inject cement milk (14) into the form (4) and replace it with the muddy water (10) to start the shield machine (16) Reach (1
5) Step 4 of placing concrete wall (13) at the corresponding part 4 Subway reinforced concrete continuous wall (12) as described above
Step 5 of excavating the ground (1B) inside and forming a shaft (1C) after forming the shaft. (5) Dismantling and removing the formwork (4), and also corresponding to the wellhead (15) from the shaft (1C) side. Step 6 of Attaching Partition Wall (15A) to Part The present invention provides a subway reinforced concrete continuous wall construction method comprising the above steps 1, 2, 3, 4, 5, and 6.

Desirably, a reinforcing material (6) for the filling concrete wall (13) is previously incorporated in the form (4) so as to be able to be pulled out upward.

[Action]

In the present invention, when the reinforcing bar cage (3) is built in the vertical groove (1), the reinforcing bar (3) is installed in a formwork (4) incorporated in a portion corresponding to a shield machine (16) start reaching wellhead (15). Since the muddy water (10) in which the beads (9) are dispersed is filled, the stable liquid (2) in the vertical groove (1) does not enter the mold (4). Since the specific gravity of the beads (9) is 1.0 to 1.2, the mud (10) has substantially the same specific gravity as the surrounding stable liquid (2). It is not substantially mixed with 2). When the cement milk (14) is injected into the mold (4), the cement milk (14) is replaced with the mud (10). At this time, beads (10) dispersed in the mud (10) are used. By the filtering effect of 9), the cement particles in the cement milk (14) are prevented from being trapped by filtering and escaping out of the mold (4) together with the muddy water (10). That is, the cement milk (14) is replaced without substantially mixing with the mud (10). The beads (9) in the muddy water (10) serve as a filler to reinforce the filling concrete wall (13) formed by remaining in the cement milk (14).

In this way, the shield machine (16) launch arrival wellhead (15)
Although a concrete filling wall (13) is formed in a considerable portion, if the reinforcing material (6) of the concrete filling wall (13) is previously incorporated into the formwork (4) so as to be able to be pulled out upward, the above-mentioned structure is obtained. The reinforcing material (6) reinforces the filling concrete wall (13). The reinforcing material (6) is pulled up from the filling concrete wall (13) and removed when the shield machine (16) reaches the start. The shield machine (16) cuts the filled concrete wall (13) to open a wellhead (15), and starts or arrives. At this time, the earth and sand from the ground (1A) and (1B) sides Collapse and groundwater intrusion are blocked by a bulkhead (15A).

〔The invention's effect〕

Therefore, in the present invention, since the formwork pre-installed in the reinforcing rod cage built in the vertical groove is filled with muddy water in which beads are dispersed, when the cement milk is injected into the formwork, it is mixed with the stable liquid in the vertical groove. Is prevented, and a concrete-filled concrete wall having a predetermined strength can be easily obtained. And since the shield machine directly cuts and starts or arrives at the filled concrete wall, there is no need for a conventional mirror cutting work, noise, reduction in work efficiency,
Deterioration of the working environment is eliminated. In addition, since the sediment collapse and groundwater intrusion from the ground side are prevented by the partition walls, freezing treatment and chemical liquid injection treatment are not required, and even when connecting to a deep and large-diameter underground tunnel, it is inexpensive and highly reliable. It can be done with safety.

〔Example〕

The present invention will be described with reference to an embodiment shown in FIGS. 1 to 12. (1) is a vertical groove, which is dug by an excavator in the same manner as in the prior art in step 1 and has a stable liquid of muddy water inside. (2) is filled to counter the earth pressure and groundwater pressure from the ground (1A) and (1B). (3) is a steel cage built in the vertical groove (1) from the step 2, and a steel formwork (4) is incorporated in a part of the steel cage (3) corresponding to a shield machine start reaching wellhead. I have. The formwork (4) includes a cylindrical side wall (4A), an outer bottom plate (4B), an inner bottom plate (4C), and a reinforcing rib (4D) interposed between the outer bottom plate (4B) and the inner bottom plate (4C). ) And a reinforcing ring (4E), and a mounting guide (4F) extending outward from the outer bottom plate (4B).
The inner bottom plate (4C) is connected to a cement milk injection pipe (5) as shown in FIGS. 1 and 2 by a separate brush (4G) attached to the peripheral edge of the cylindrical side wall (4A). A plurality of nozzles (4H) are arranged. A steel pipe (6) as a reinforcing material for the concrete filling and a storage tube (7) for storing the steel pipe (6) are incorporated in the formwork (4). The mud pipe (5A) contacts. As shown in FIGS. 4 and 5, the steel pipe (6) has a rib (6A) having a ten-shaped cross section inserted therein, and by adopting such a structure, an external force applied to the steel pipe (6) is reduced. The ribs (6A) alleviate dispersion and prevent deformation of the steel pipe (6). Further, a bottom cover (6B) provided with an air vent (6C) is attached to the lower end of the steel pipe (6). The bottom cover (6B) prevents concrete from entering the steel pipe (6) when the steel pipe (6) is erected in the concrete-filled concrete wall. The bottom cover (6B) is provided with an air vent (6C) to release the internal pressure of the steel pipe (6). Further, the periphery of the steel pipe (6) is covered with a hard thermoplastic layer (6D).
A solvent introduction space (6E) is formed inside the thermoplastic layer (6D). As a material of the thermoplastic layer (6D), a rigid thermoplastic such as polyvinyl chloride, polystyrene, polymethacrylate, acrylonitrile-butadiene-styrene copolymer or a foam of the thermoplastic is used.
It preferably has a strength equal to or higher than the strength of the filled concrete wall, and the hard thermoplastic layer (6D) buffers external forces from the ground side from the filled concrete wall to the steel pipe (6). Be able to communicate. The storage tube (7) installed above the formwork (4)
The diameter of the steel pipe (6) (hard thermoplastic layer (6
D) is also slightly larger than the diameter of the steel pipe (6) so that the friction coefficient between the steel pipe (6) and the storage pipe (7) is as low as possible, and the length of the storage pipe (7) is It should be of a size that can accommodate the length. Then, as shown in FIG. 6, a steel rod (8), which is an operation rod, communicates with the head of the rib (6A) of the steel pipe (6) via a storage cylinder (7). The periphery of the steel rod (8) is covered with a thermoplastic foam layer (8A) similar to that used for the thermoplastic layer (6D). The foam layer (8A) is usually 3-4k
It has a compressive strength of about g / cm ² and reduces the frictional resistance between the steel bar (8) and the concrete to facilitate the drawing of the steel bar (8).

When building the reinforcing rod cage (3) in the above step 2, the form (4) is filled with muddy water (10) in which beads (9) having a specific gravity of 1.0 to 1.2 are dispersed. The bead (9) is made of a plastic such as polystyrene, polymethacrylate, polyethylene, or polypropylene, or an inorganic hollow sphere such as a shirasu balloon or a glass balloon. The plastic includes calcium carbonate, talc, blast furnace slag, and fly for adjusting specific gravity. A filler such as ash may be added. The bead (9) is usually added to the muddy water (10) in an amount of about 70 to 100% by volume. The mud (10) in which the beads (9) are dispersed has substantially the same specific gravity as the stabilizing liquid (2) in the vertical groove (1), and when the rebar cage (3) is built in the step 2, the mud (10) ) Is not substantially mixed with the stabilizing solution (2), so that the muddy water (10) prevents the stabilizing solution (2) from entering the mold (4). The separate brush (4G) of the mold (4) prevents the beads (9) in the muddy water (10) from leaking to the outside of the mold (4). Further, when the formwork (4) is set in the vertical groove (1), it is guided by the building guide (4F) and sinks in the vertical groove (1). Since the space (4I) is formed between the outer bottom plate (4B) and the inner bottom plate (4C), buoyancy based on the space (4I) acts on the formwork (4) to build the reinforcing cage (3). In this case, the weight can be balanced. Further, the formwork (4) is reinforced by such a double bottom structure, and the shape is maintained.

After the rebar cage (3) has been built, concrete (11) is cast from the lower portion of the vertical groove (1) in step 3 as shown in FIG. 7 to reinforce the concrete with the rebar cage (3). Form a continuous wall (12). The concrete wall (1
After the formation of 2), cement milk (14) is injected into the mold (4) via the injection pipe (5) in step 4 as shown in FIG. Cast concrete wall (13). At this time, the cement milk (14) used is mixed with a viscous soil such as bentonite or clay to control the strength of the concrete wall (13). When the cement milk (14) is injected into the formwork (4), the muddy water (10) in which the beads (9) are dispersed is discharged to the ground via a mud pipe (5A), and the inside of the formwork (4) is cement milk. Although replaced by (14), the cement is mixed with the muddy water (10) and flows into the mud drain pipe (5A) due to the filtering effect of the cement in the cement milk (14) by the beads (9). Is prevented. Thus, the cement milk (14) poured into the mold (4) is replaced with the muddy water (10) without being substantially mixed with the muddy water (10), and a concrete wall (13) with a predetermined strength is obtained. However, at this time, the beads (9) remain in the cement milk (14) and serve as a filler for reinforcing the filling concrete wall (13). In this embodiment, the strength of the obtained concrete-filled concrete wall (13) is 12
Although it is 0 to 150 kg / cm ² , in the present invention, the strength of the concrete-filled concrete wall (13) is not particularly limited, and is usually about 70 to 240 kg / cm ² . Then the inner ground (1
A) is excavated to form a shaft (1C), and then the outer bottom plate (4B) and the inner bottom plate (4C) of the formwork (4) are removed and, as shown in FIG. Steel ring (15
A) is attached to make a partition.

In this way, the shield machine start arrival wellhead (15) is configured. When the shield machine is started from the wellhead (15), the shield machine (16) is first set in the shaft (1C) as shown in FIG. The wellhead (15) of steel ring (15
A) As shown in FIG. 12, the inner surface of the steel ring (15A) has an entrance packing (17A) on the outer end side and an airbag (1) as shown in FIG.
7B) is attached, and an air pipe (17C) communicates with the inside of the airbag (17B) from the outside. The airbag (1
7B) is attached to the steel ring (15A) by bolts (17D) via washers (17E). The entrance packing (17A) and the airbag (17B) are made of synthetic rubber or natural rubber such as styrene-butadiene rubber, acrylonitrile-butadiene rubber, chloroprene rubber, isoprene rubber, ethylene-propylene rubber, urethane rubber and silicone rubber. . The space (18) in front of the shield machine (16) is charged with a lubricating liquid (19) to be used as a lubricant when the shield machine (16) cuts the filled concrete wall (13), and at the same time, the space (18) is used. 18) The lubricating liquid (19)
The inner surface of the shield machine (16) penetrates the packed concrete wall (13) and penetrates the ground (1B). (17B) to prevent. The lubricating liquid is, for example, a dispersion liquid in which clay, bentonite, or the like is dispersed in water. If desired, the lubricating liquid may include a lubricating water-soluble compound such as polyacrylate, polyvinyl alcohol, carboxymethyl cellulose, or alginate. A resin may be added.

Then, prior to the start of the shield machine (16), the steel pipe (6) of the concrete wall (13) is pulled upward. In drawing out the steel pipe (6), first, a solvent for dissolving or swelling the hard thermoplastic layer (6D) is introduced into the solvent introduction space (6E) of the hard thermoplastic layer (6D) of the steel pipe (6). The introduction of the solvent is carried out from the ground via a solvent pipe (20) communicating with the upper end of the storage cylinder (7). As the solvent used in the present invention, methanol, ethanol, isopropanol, alcohol solvents such as n-butanol, toluene, aromatic solvents such as xylene, ethyl acetate, acetate solvents such as n-butyl acetate, acetone, methyl ethyl ketone, Low-toxic organic solvents such as ketone solvents such as methyl isobutyl ketone, cellosolve solvents such as cellosolve acetate and n-butyl cellosolve, and chlorine solvents such as dichloroethane, trichloroethylene and carbon tetrachloride are used. When the hard thermoplastic layer (6D) comes into contact with the solvent, the hard thermoplastic layer (6D) swells to become a lubricating layer between the steel pipe (6) and the filling concrete wall (13), It also melts to form a gap between the steel pipe (6) and the concrete filling wall (13), or swells and shrinks in the solvent when the hard thermoplastic layer (6D) is a low foam. By doing so, a gap is formed between the steel pipe (6) and the filled concrete wall (13). The steel rod (8) slides in the foam layer (8A). In this case, the frictional resistance between the steel rod (8) and the foam layer (8A) is almost negligible, and the pull-out resistance is substantially reduced when the steel pipe (6) is pulled out from the concrete wall (13). The pull-out resistance of the steel rod (8) is almost independent of the depth of the wellhead (15) because it is governed by the frictional resistance when stored in the cylinder (7), and the frictional resistance swells or dissolves in the solvent. In the present invention, even if the wellhead (15) is located at a large depth, the steel pipe (6) can be smoothly pulled out from the concrete wall (13) even if the wellhead (15) is located at a great depth. It is performed in.

The steel pipe (6) is pulled out through the steel rod (8), for example, from the ground by a hydraulic jack, a multiple pulley, a vibro puller or the like. In this manner, the steel pipe (6) is pulled out from the concrete-filled concrete wall (13) and stored in the storage cylinder (7) as shown by the dotted line in FIG. At this time, air pressure is applied from the air pipe (17C) to the inside of the airbag (17B) to be pressed against the skin plate (16A) of the shield machine (16). In this way, the ground packing (17A) prevents the inflow of groundwater and earth and sand from the outer ground side (1B) when the shield machine (16) starts, and the entrance packing (17A) also has a skin plate of the shield machine (16). (16A) is pressed against to assist the airbag (17B) in sealing. The internal pressure of the airbag (17B) is
The pressure is equivalent to the water pressure, earth pressure from B) or the jack pressure of the shield machine (16), and is usually about 0.5 to 10 atm.

As described above, the shield machine (16) moves in the direction of the arrow in FIG. 11, cuts the concrete wall (13) of the wellhead (15), breaks through, starts, and penetrates the ground side (1B).

FIG. 13 shows a state in which the shield machine (16) arrives from the ground (1B) outside the wellhead (15) of the reinforced concrete continuous wall (12). When the shield machine (16) is reached, a steel ring (15A) is added to the steel ring (15A) at the wellhead (15).
B) is attached, and the steel receiving box (15B) is filled with earth and sand (19A) to counter the water pressure and earth pressure exerted from the outer ground (1B).

Prior to the shield machine (16) reaching the arrival wellhead (15), the steel pipe (6) is pulled from the concrete wall (13) through the steel rod (8) in the same manner as when the shield machine (16) is started. At this time, the hard thermoplastic layer (6D) is heated and softened through the steel pipe (6) by passing an electric current through the steel pipe (6). The hardened thermoplastic layer (6D) thus serves as a lubricating layer between the steel pipe (6) and the concrete wall (13), or the volume if the rigid thermoplastic layer (6D) has a low foaming structure. Shrinkage causes a gap between the steel pipe (6) and the filled concrete wall (13), and the frictional resistance when the steel pipe (6) is pulled out from the filled concrete wall (13) is extremely reduced. .

In this way, the steel pipe (6) is pulled out from the filling concrete wall (13) through the steel rod (8) and stored in the storage tube (7), and then the arrow shown in FIG. As shown in the figure, the shield machine (6) reached the concrete wall (1)
3) Cut and break through the soil (19B) in the steel receiving box (15B).
A) is stored in the steel receiving box (15B) while shaving. After that, after stopping the water treatment on the back surface of the shield machine (16) in the housed state by means of injection and hardening of a water stopping agent, the steel receiving box (15B) is dismantled, and the shield machine (16) is buried. Alternatively, a collection operation is performed.

[Brief description of the drawings]

1 to 12 show an embodiment of the present invention.
FIG. 1 is a side sectional view of a standing groove portion in a state in which a reinforcing cage is built, FIG. 2 is a front view of a cutout of an outer bottom plate of a formwork, FIG. 3 is a longitudinal sectional view of the formwork, and FIG. 5, FIG. 5 is a cross-sectional view of a steel pipe, FIG. 6 is a vertical cross-sectional view of an upper part of a storage tube, FIG. 7 is a side cross-sectional view of a vertical groove in a concrete casting state, and FIG. FIG. 9 is a side sectional view of a vertical groove portion in a state where a filling concrete wall is formed, FIG.
Fig. 11 is a side sectional view of a reinforced concrete continuous wall with a steel ring attached. Fig. 11 is an explanatory view when a shield machine is started.
FIG. 12 is an enlarged sectional view of a shield part, and FIG. 13 is an explanatory view of another embodiment of the present invention when the shield machine is reached. In the figure, (1) ... vertical groove, (2) ... stable liquid, (3) ...
Reinforcing cage, (4) ... formwork, (6) ... steel pipe, (9) ...
Beads, (10) ... muddy water, (13) ... concrete-filled concrete wall, (14) ... cement milk, (15) ... wellhead, (15)
A) ... steel ring, (16) ... shield machine,

Claims (2)

(57) [Claims] 1. A step of forming a vertical groove by excavating the ground with an excavator by injecting a stabilizing liquid. 1. A reinforcing cage having a formwork incorporated at a portion corresponding to a wellhead for starting a shield machine in the vertical groove. Step 2: Filling the form with muddy water in which beads having a specific gravity of 1.0 to 1.2 are dispersed. Step 2: Placing concrete from the lower part of the vertical groove. Step 3: Inject cement milk into the form to replace the muddy water. Step 4 of placing a filled concrete wall at a portion corresponding to the entrance of the shield machine starting arrival and forming the continuous subway reinforced concrete wall as described above, and then excavating the ground inside to form a shaft 5 Step 6 of dismantling and removing the formwork and attaching a bulkhead from the side of the shaft to the part corresponding to the wellhead. Subway reinforced concrete continuous wall method consisting of the above steps 1, 2, 3, 4, 5, and 6 2. The subway reinforced concrete continuous wall construction method according to claim 1, wherein a reinforcing material for the filling concrete wall is incorporated in the formwork in advance so as to be able to be pulled upward.