JP3473379B2 - Underground hydraulic method - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an underground water supply method.
The flow of groundwater, especially after constructing a waterproof underground wall.
It relates to the underground water flow method that enables water to pass.

[0002]

2. Description of the Related Art As is well known, when constructing an underground structure, for example, an underground tunnel for a subway or a dedicated road for vehicles by an excavation method, it is possible to prevent the ground from collapsing and excavate the interior. In order to achieve this, an underground wall with a water stop is constructed.

Various methods are provided for constructing this type of underground wall, including the underground continuous wall method, but the underground continuous wall method and the column wall method are used. The underground wall may be left in the ground even after the main body of the underground structure is constructed.

By the way, if the underground wall provided with waterproofing is left in the ground, the groundwater flow is blocked, and the water vein on the downstream side of the underground wall is cut off. However, inconvenience such as the subsidence of the ground occurs.

Therefore, for example, in Japanese Unexamined Patent Publication No. 6-49839, it is possible to secure water-stopping when constructing the main body of an underground structure and ensure water permeability when the main body is completed. A wall construction method is disclosed.

In the construction method disclosed in this publication, the underground wall is constructed by the underground continuous wall construction method. When the underground wall is constructed, a hollow circle or a square shape is present in the excavation trench. A hole tube or a special water-permeable frame in which a steel mesh is placed in the ground side opening is installed in the vertical direction, and an impermeable and stretchable tubular body is inserted into this water-permeable frame. Concrete is poured in a state where the water pressure inside the tubular body is higher than the surrounding water pressure, and after the concrete has hardened, the tubular body is removed from the special water passage frame, and a perforated pipe or natural side opening Water permeability is given to the underground wall by the steel mesh placed in the section.

The special water-passing frame is sized to penetrate the underground wall in the thickness direction or to partially replace the underground wall in the thickness direction, and the inside thereof is filled with crushed stone. It However, such conventional underground water flow method
Have had technical problems to be described below.

[0008]

That is, in the underground water supply method of the above publication, in order to impart water permeability to the underground wall,
Since the whole or part of the underground wall in the thickness direction is replaced with the special frame over the entire length in the depth direction, this part may become a structural weak point.

In the method disclosed in this publication,
Since a perforated pipe etc. is built in the excavation trench filled with muddy water, a muddy water film may adhere to the through hole of the perforated pipe and cause clogging, and when placing concrete. , A cylindrical body is inserted inside it to prevent the concrete from wrapping around, but since this cylindrical body is inserted inside the water passage frame body such as a perforated pipe, the through hole of the perforated pipe is There is a problem that cement or the like may enter the inside to cause clogging, and the water permeability of the underground wall is lowered.

The present invention has been made in view of such conventional problems, and the object thereof is not to become a structural weak point and to sufficiently pass water through the underground wall. It is to provide the underground water supply method that can be secured.

[0011]

In order to achieve the above object, the present invention is constructed by placing concrete in an excavation trench.
The water-blocking underground wall is formed so as to block an underground waterway in the ground, and after the underground wall is formed, the inside is excavated,
In the underground water supply method of forming a water passage for communicating between the ground water passages, in the water passage, the ground side is closed by a water permeable material that restores water permeability by decomposition of the biodegradable resin, and the excavation side is an inner end. is closed by a plate, is composed of the installed telescopic steel water passage tube so as to cross the thickness direction of the diaphragm wall, in constructing the water cut-off diaphragm wall, the drilling
Before the concrete is poured into the digging groove, the water permeable material is pressed by the pressing means against the excavation wall surface of the excavation groove on the natural ground side. According to the underground water supply method constructed in this way, the ground side of the steel water pipe is closed with a water permeable material that restores water permeability by decomposition of the biodegradable resin, and the ground water side is confined inside the excavation trench.
Before the cleat is placed, the permeable material is pressed against the excavated wall surface on the ground side by the pressing means, so that concrete is prevented from wrapping around the permeable member side, and microorganisms, bacteria existing in the ground, The water permeability is restored when the biodegradable resin is decomposed and removed by mold and the like. When the water permeability of the water permeable material is restored, a water passage that penetrates between the water-blocking underground walls is formed, and the cutoff of the ground water passage is released. Since the steel water pipe whose ground side is blocked by the water permeable material is buried in the cross-sectional direction of the waterproof underground wall, this portion does not become a structural weak point. The water pipe, the water permeable material, and the inner end plate that constitute the water passage are
When constructing the waterproofing underground wall, it is attached to a rebar cage built in the excavation groove, and after the rebar cage is installed in the excavation groove, the water-permeable material is pressed against the excavation wall surface on the natural ground side. be able to. According to this configuration, the water passage can be easily installed by following the procedure for constructing the water impermeable underground wall. In addition, a block filter material such as crushed stone or gravel can be filled in the steel water pipe. With this configuration, it is possible to resist the earth pressure applied to the steel water pipe, and it is possible to form a water passage in a large depth with a simple structure.
Become Noh.

[0012]

Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings. Figure 1
2 and FIG. 2 show an embodiment of the underground water supply method according to the present invention.
Is shown .

In the construction method shown in the figure, a sandy soil layer 10 having water permeability is sandwiched and a viscous soil layer 12 having no water permeability is provided above and below the sandy soil layer 10.
It is an application example in the case of constructing the water-stopping underground wall 14 in the ground where the existing water is present, and the construction of the water-stopping underground wall 14 causes the underground waterway (between the sandy soil layers 10 in FIG. 1) to be formed. Be cut off.

Therefore, after the underground wall 14 is constructed, the water passage 16 for connecting the underground water passages is formed. In the case of the present embodiment, the underground wall 14 is constructed by the underground continuous wall construction method, excavates and forms the excavation groove 18 in the ground, and the rebar cage 20 is formed.
It is formed by pouring concrete 21 after the building is built.

The water passage forming the water passage 16 is , as shown in detail in FIG. 2, a water pipe 22 made of a stretchable steel pipe.
The hydraulic jacks 24 (pressing means) arranged in multiple stages along the depth direction are the main constituent members.

These water pipe 22 and hydraulic jack 2
4 are arranged in parallel to the rebar cage 20 so as to orient in a substantially horizontal direction and coaxially in the depth direction. The water flow pipe 22 is a double pipe made of a steel inner pipe 22a and an outer pipe 22b, and is open at both ends.

The open end of the inner pipe 22a is on the natural ground side A and is closed by the water permeable material 26. This water permeable material 26
Is the water permeable mat 26a and the natural side A of the water permeable mat 26a
And a biodegradable plastic sheet 26b attached so as to be located at.

The water-permeable mat 26a is formed by randomly entwining coil-shaped synthetic resin fibers having a relatively large diameter,
For example, Cosmo Geomat (manufactured by Toyobo Co., Ltd., trade name) can be used.

The biodegradable plastic sheet 26b is decomposed by microorganisms, bacteria, molds and the like existing in the ground, and for example, super paper (trade name, manufactured by Shin-Etsu Polymer Co., Ltd.) is used. You can

The open end of the outer pipe 22b is on the excavation side B and is closed by an inner end plate 28 so as to be openable and closable. The inner end plate 28 is bolted to a connecting flange plate 28a fixed to the open end of the outer pipe 22b and to a position outside the flange plate 28a and corresponding to the open end of the outer pipe 22b. And a detachable temporary fixing plate 28b.

An outer end plate 32 is fixedly provided around the open end of the inner pipe 22a on the natural side A. This outer end plate 32
Has a recess 32a for accommodating the water-permeable material 26 in the central portion along the depth direction, and is provided over the entire length thereof, and the water-permeable material 26 has substantially the same length and width as the recess 32a.

Flat portions 32b are provided on both sides of the recess 32a. A flexible member 32c such as a rubber sheet is fitted and fixed to the outer periphery of the flat portion 32b.

A hydraulic hose (not shown) is connected to each of the hydraulic jacks 24, and each hydraulic hose extends to the ground side. Each hydraulic jack 24 has a main body 24a.
And a pair of telescopic plungers 24b and 24c provided on both sides of the main body 24a.

The tip of the plunger 24b, which expands and contracts toward the natural ground side A of each hydraulic jack 24, has a concave portion 3 of the outer end plate 32.
It is fixed to the back side of 2a. A reaction force plate 34 is fixed to the tip of each plunger 24c that expands and contracts toward the excavation side B of each hydraulic jack 24.

Next, a method of forming the water passage 16 by using the underground water passage having the above-mentioned structure will be described. Since the water passage 16 is formed after the water blocking underground wall 14 is constructed, the water blocking underground wall 14 is first constructed.

The underground wall 14 is constructed by piercing the excavation groove 18 through the sandy soil layer 10 to the lower side of the lower cohesive soil layer 12 and then installing the rebar cage 20 in the excavation groove 18. Then, it is performed by placing concrete 21 in the excavation groove 18.

At this time, the water pipe 22 and the hydraulic jack 24 are previously locked to the rebar cage 20 at predetermined positions (positions in the sandy soil layer 10). Inside the water pipe 22,
The outer end plates 28 and 32 are fixed to each other, the opening end of the excavation side B is closed by the inner end plate 28 so as to be openable and closable, and the water permeable material 26 is housed in the recess 32a of the outer end plate 32. The open end on the natural ground side A is closed.

In this case, when the water permeable material 26 is accommodated, the outer surface of the biodegradable plastic sheet 26b attached to the water permeable mat 26a coincides with the surface of the flat portion 32b of the outer end plate 32, or Make it protrude slightly outward.

Further, by filling the water pipe 22 with a block filter material such as crushed stone or gravel, it is possible to counteract the earth pressure applied to the water pipe 22, and the water passage 16 can be provided at a large depth with a simple structure. Can be formed.

A plunger 24b on the natural side A is fixed to each jack 24 on the back side of the outer end plate 32, and a reaction plate 34 is fixed to the plunger 24c on the excavation side B, respectively.

When the rebar cage 20 in which the water pipe 22 and the hydraulic jack 24 are locked is installed at a predetermined position, the hydraulic jack 24 is driven by an operation from the ground side before the concrete 21 is placed. .

When each of the hydraulic jacks 24 is driven, the telescopic plungers 24b and 24c are respectively on the natural side A and the excavating side B.
And the extension of the plungers 24b and 24c
The flat portion 32b of the outer end plate 32 is pressed against the excavation wall surface on the natural side A, and the reaction plate 34 is pressed against the excavation wall surface on the excavation side B.

During such a pressing operation, the water pipe 22 has a double pipe structure and expands and contracts, so that this operation is not hindered. Further, since the flexible member 32c is fitted and fixed to the outer peripheral portion of the flat portion 32b of the outer end plate 32, the flexible member 32c is deformed according to the unevenness of the excavation wall surface, and the flat portion 32b is formed. Adhere closely to the excavated wall.

When such a pressing operation is completed, concrete 21 is placed in the excavation groove 18 and the placed concrete 21 is hardened to construct the underground wall 14. When placing concrete 21, concrete 21
Tries to go inward from the outer peripheral portion of the flat portion 32b, but since the flat portion 32b is in close contact with the excavation wall surface with the flexible member 32c interposed, the concrete 21
The wraparound is surely prevented.

When the construction of the underground wall 14 is completed, the excavation side B
The ground is excavated and a structure is built inside the underground wall 14. At this time, in the present embodiment, after excavating to the root excavation surface C, excavation is performed to a deeper depth to expose the inner end plate 28 that closes one end of the water pipe 22.

When the inner end plate 28 is exposed, the bolts of the temporary fixing plate 28b are removed and removed, and the outlet pipe 36 is communicatively connected to the open end of the water pipe 22 to backfill it. In addition,
For example, when the water blocking underground wall 14 is provided so as to face each other, the lead-out pipe 36 can be provided to connect the water passages 22 provided on the underground wall 14 to each other, The outlet pipe 36 is not always necessary, and the water pipe 2
The open end of 2 may be opened in the sandy soil layer 10.

After a predetermined period of time elapses after the underground wall 14 is constructed in this way, the biodegradable plastic sheet 26b in contact with the excavated wall surface on the ground side A is the microorganisms existing in the ground. When it is decomposed by bacteria, mold, etc., the opening of the water conduit 22 on the ground side A is released, and the water conduit 16 that connects the sandy soil layers 10 sandwiching the underground wall 14 is formed.

According to the underground water flow method constructed as described above, when the biodegradable plastic sheet 26b is decomposed and removed and the water permeability of the water permeable material 26 is restored, the water permeable underground wall 14 is penetrated. The water passage 16 is formed, and the blockage of the underground water passage is released.

Since the steel water pipe, which is closed on the ground side by the water permeable material, is buried in the cross-sectional direction of the water blocking underground wall, this portion does not become a structural weak point.

Further, in the case of the present embodiment, the water pipe 22, the water permeable material 26, and the inner end plate 28 which form the water passage 16 are provided in the excavation groove 18 when the waterproof underground wall 14 is constructed. Since it is attached to the rebar cage 20 that is built in,
By following the construction procedure of, the water passage 16 can be easily installed.

[0041]

As described above in detail in the embodiments,
According to the underground water flowing method according to the present invention, without becoming a structural weak point, while preventing the wraparound of concrete,
It is possible to secure sufficient water permeability of the underground wall.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view of an essential part showing an embodiment of an underground water supply method according to the present invention.

FIG. 2 is an enlarged perspective view of a main part of FIG.

[Explanation of symbols]

10 Sandy soil layer 12 Cohesive soil layer 14 underground wall 16 waterways 18 excavation ditch 20 Rebar cage 21 concrete 22 Water pipe 22a inner tube 22b outer tube 24 Hydraulic jack (pressing means) 26 Water-permeable material 26a Water-permeable mat 26b Biodegradable plastic sheet 28 Inner end plate 28a Connection flange plate 28b Temporary fixing plate 32 outer end plate 32a recess 32b flat part 32c flexible member A ground side B Excavation side

─────────────────────────────────────────────────── --- Continuation of the front page (56) References JP-A-9-324417 (JP, A) JP-A-9-228360 (JP, A) JP-A-7-268863 (JP, A) JP-A-5- 311643 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) E02D 5/20 102 E02D 5/18 102

Claims (3)

(57) [Claims] 1. Construction by placing concrete in the excavation trench
The water-blocking underground wall is formed so as to block an underground waterway in the ground, and after the underground wall is formed, the inside is excavated,
In the underground waterway construction method for forming a waterway for communicating between the groundwaterways, the waterway is closed on the ground side with a water-permeable material that restores water permeability by decomposition of the biodegradable resin, and the excavation side is an inner end. is closed by a plate, is composed of the installed telescopic steel water passage tube so as to cross the thickness direction of the diaphragm wall, in constructing the water cut-off diaphragm wall is co into the excavation groove
An underground water passage method, characterized in that the water permeable material is pressed against the excavation wall surface of the excavation groove on the side of the natural ground before the concrete is placed by pressing. 2. A water pipe, a water permeable material, which constitutes the water passage,
The inner end plate is attached to a rebar cage built in the excavation groove when constructing the water-proof underground wall, and after the rebar cage is installed in the excavation groove, the water-permeable material is attached to the rock side. The underground water supply method according to claim 1, wherein the underground water supply method is pressed against the excavated wall surface. 3. The underground water supply method according to claim 1, wherein the steel water pipe is filled with a lumped filter material such as crushed stone or gravel in advance.