JP6534208B2 - Tunnel tarpaulin - Google Patents

Description

  The present invention relates to a tarpaulin provided between a primary lining and a secondary lining in a tunnel.

  For example, Patent Document 1 discloses a tunnel construction method including installation of a waterproof sheet. According to it, spray concrete is sprayed on the ground excavated surface of the tunnel. A formwork is installed to face the shotcrete, and a waterproof sheet is stretched on the outer peripheral surface of the formwork. Next, the waterproof sheet is fixed to the backfill material by filling the gap between the sprayed concrete and the waterproof sheet with the solidifying backfill material. This backfill material will be the primary lining work. After that, cast a second lining concrete. As a result, the tarpaulin is embedded as being sandwiched between the primary lining and the secondary lining. The details of the material and structure of the tarpaulin are not disclosed.

  Patent Document 2 discloses a waterproof sheet applied to the NATM method or the like. This waterproof sheet is a laminate of a water impermeable sheet portion and a water permeable sheet portion. The water-permeable sheet portion has a three-layer structure in which a mesh-like body layer is sandwiched between two non-woven fabric layers. The permeable sheet portion faces the primary lining, and the impermeable sheet portion faces the secondary lining. According to this waterproof sheet, not only can the spring water from the ground be prevented from flowing into the second lining, but the water-permeable sheet portion can be smoothly drained because the spring passage is formed. In particular, even if the non-woven fabric layer of the surface layer in contact with the primary lining is clogged with soil, etc., the reticulated layer can secure the passage of spring water.

Patent No. 4044719 Unexamined-Japanese-Patent No. 01-111999

In conventional tunnel construction methods such as the NATM method, the waterproof sheet is usually fixed to primary lining concrete by nails.
On the other hand, in patent document 1, it replaces with a nail and adheres a waterproof sheet with a backing material. When the waterproof sheet of Patent Document 2 is applied to the method of Patent Document 1, the backfilling material before solidification penetrates into the inside of the non-woven fabric layer of the surface layer and further easily penetrates into the inside of the reticulated layer. And, by the solidification of the backfill material and blocking the passage of the spring water, the drainage function may be lost.
In view of such circumstances, the present invention maintains the drainage function of the water-permeable sheet portion even when applied to a method in which a waterproof sheet is provided between a primary lining and a secondary lining in a tunnel and is fixed with a backfill material. The purpose is to provide a waterproof sheet that can be used.

In order to solve the above-mentioned problems, the present invention is a waterproof sheet provided between a primary lining and a secondary lining in a tunnel,
The water impermeable sheet portion facing the secondary lining, and a water permeable sheet portion laminated on the water impermeable sheet portion, the water permeable sheet portion being
A first permeable layer facing said primary lining;
A second permeable layer laminated to the first permeable layer;
A third water permeable layer laminated between the second water permeable layer and the water impermeable sheet portion;
And the second water permeable layer is lower in water permeability than the first water permeable layer and the third water permeable layer.

Preferably, the waterproof sheet is disposed to face the spray concrete of the tunnel with a gap, and is fixed to a primary lining made of a backfill material filled in the gap.
According to this waterproof sheet, the backfill material intrudes into the first water permeable layer when the backfill material is filled. At this time, the low water permeability second water permeable layer can prevent or suppress the penetration of the backfill material to the third water permeable layer. Eventually, the backfill material solidifies. The backfilling material that has entered the first water permeable layer also solidifies. This makes it possible to securely fix the backfill material, ie, the primary lining and the waterproof sheet.
When spring water from the ground reaches the waterproof sheet through the primary lining, it is possible not only to block water permeation to the secondary lining by the impermeable sheet part but also to drain the permeable sheet part It can drain as a road. In particular, the third water-permeable layer in the water-permeable sheet portion can reliably function as a drainage channel. For example, when a hair crack is formed to reach the waterproof sheet across the primary lining due to drying shrinkage, earthquake, etc., the water pressure of the waterproof sheet on the waterproof sheet by the hair crack becoming a passage of spring water. It takes When the water pressure exceeds a certain level, the spring water permeates through the second permeable layer in the thickness direction and flows into the third permeable layer. Thereby, the third water permeable layer can be reliably drained as a drainage channel.
Furthermore, when solid components, such as earth and sand and lime, are mixed in the spring water, solid components can be captured by the second water permeable layer. Therefore, clogging of the third water-permeable layer can be prevented or suppressed for a long period of time, and the drainage function can be reliably maintained.

It is preferable that the thickness of the said 2nd water-permeable layer is 0.03 times-0.3 times the thickness of the said water-permeable sheet part.
While being able to ensure stability of processability and quality by this, the rise in price can be suppressed.

  According to the waterproof sheet of the present invention, the drainage function of the water-permeable sheet portion can be maintained even when applied to a tunnel method fixed by a backfill material.

FIG. 1 is a front cross-sectional view of a tunnel including a waterproof sheet according to an embodiment of the present invention. FIG. 2 is an enlarged cross-sectional view of the circle portion II of FIG.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
As shown in FIG. 1, the ground 2 is excavated to form a tunnel 1. The tunnel 1 includes a shotcrete 3, a primary lining 4, a tarpaulin 5, and a secondary lining 6 from the ground 2 side. Shot concrete 3 is sprayed on the ground excavated surface 2a. The primary lining 4 is a solidifying backfill consisting of, for example, a mortar 4 b. A tarpaulin 5 is fixed to the primary lining 4. A tarpaulin 5 is sandwiched between the primary lining 4 and the secondary lining 6. The secondary lining 6 is made of reinforced concrete or non-reinforced concrete.

  As shown in FIG. 2, the waterproof sheet 5 has a laminated structure of the water impermeable sheet portion 10 and the water permeable sheet portion 20. The water impermeable sheet portion 10 is directed to the secondary lining 6 side, and the water permeable sheet portion 20 is directed to the primary lining 4 side. The size of the waterproof sheet 5 is not particularly limited, but may be the same size as a conventional general waterproof sheet. For example, in the singular case, a width of about 1600 mm to 2200 mm is preferable, and a width of about 3200 mm to 11000 mm is preferable in a state in which a plurality of sheets are joined and integrated. This makes it possible to use it in the same manner as a conventional general tarpaulin.

The water impermeable sheet portion 10 has high water impermeable property. By this, it has a waterproof function to prevent the spring water from the ground 2 from flowing into the tunnel 1.
Examples of the material of the water impermeable sheet portion 10 include ethylene / vinyl acetate copolymer resin (EVA), polyolefin resin and the like. Examples of the polyolefin resin include completely nonpolar polyolefin resins such as polyethylene (PE) and polypropylene (PP). Furthermore, a modified polyolefin resin to which adhesiveness is imparted by graft polymerizing a polar group (carboxyl group) such as acrylic acid or maleic anhydride to PE or PP to give polarity may be used.

  A water-permeable sheet portion 20 is laminated on the surface (upper surface in FIG. 2) of the water-impermeable sheet portion 10 facing the primary lining 4 side. The water-permeable sheet portion 20 is responsible for the buffer function between the uneven ground excavated surface 2a (FIG. 1) and the water-impermeable sheet portion 10, the fixing performance with the primary lining 4 and the drainage function. .

  The water-permeable sheet portion 20 includes a first water-permeable layer 21, a second water-permeable layer 22, and a third water-permeable layer 23. The surface first permeable layer 21 is fixed to the primary lining 4 by facing the primary lining 4. The second water permeable layer 22 is laminated on the side of the water impermeable sheet portion 10 of the first water permeable layer 21 (lower side in FIG. 2). A third water permeable layer 23 is stacked between the second water permeable layer 22 and the water impermeable sheet portion 10.

The first water permeable layer 21 is made of a low density, high water permeability non-woven fabric. Permeability of the first permeable layer 21 is preferably 2.00 × ¹⁰ -1 cm / sec~8.50 × about ¹⁰ -1 cm / sec.
In this specification, the measurement method of hydraulic conductivity is based on the constant water method (JIS A 1218).
The thickness of the first water permeable layer 21 is preferably about 3 mm in consideration of the adhesion performance with the primary lining 4 and the buffer performance.

The second water-permeable layer 22 is composed of a high density non-woven fabric and has extremely low water permeability. In short, the second water-permeable layer 22 is lower in water permeability than the first water-permeable layer 21, and further lower in water permeability than the third water-permeable layer 23. The water permeability coefficient of the second water permeable layer 22 is preferably about 1 × 10 ⁻² cm / sec to 1.5 × 10 ⁻¹ cm / sec.
The thickness of the second water permeable layer 22 is preferably about 0.03 times to 0.3 times the thickness of the entire water permeable sheet portion 20, and 0.05 times to 0.2 of the thickness of the whole water permeable sheet portion 20. Double is more preferable. If it is less than 0.03 times, processing becomes difficult and it becomes difficult to stabilize the quality. If it exceeds 0.3 times, the thickness of the water-permeable sheet part 20 will increase and the price will become high.

The third water-permeable layer 23 is made of a low density and high water permeability non-woven fabric. Permeability of the third permeable layer 23 is preferably 2.00 × ¹⁰ -1 cm / sec~8.50 × about ¹⁰ -1 cm / sec.
The thickness of the third water-permeable layer 23 is preferably about 3 mm in consideration of drainage performance, buffer performance, and the like.

  The material of the non-woven fabric constituting the water permeable layers 21, 22, 23 may be a chemical fiber such as polyester or polypropylene, or may be a natural fiber such as coconut, cotton, hemp, wool or silk, glass, carbon, metal, ceramic, etc. Inorganic fibers of More preferably, it is a chemical fiber.

As a method of manufacturing the water permeable layers 21, 22, 23, for example, a method in which fibers are jetted from a large number of nozzles and entangled by wind, water, static electricity or the like, a needle punch method, a spun bond method or the like is applicable.
The water permeable layers 21 and 23 may be produced by a needle punch method, and the second water permeable layer 22 may be produced by a spun bond method. The water permeable layers 21, 22, 23 may be produced by needle punching.

In the needle punching method, felt needles that move up and down at high speed are repeatedly punched into fibers to entangle the fibers. The permeability coefficient can be adjusted by the number of times of driving. When producing the water-permeable layers 21 and 23, it is preferable to set the number of times of implantation to, for example, 6 times / cm ^{2 to} 16 times / cm ² . By this, a nonwoven fabric with a high water permeability can be obtained. When fabricating a second water-permeable layer 22, it is preferable to set the number of times driving for example 20 times ^/ cm 2 to 30 times / cm ^2. By this, a nonwoven fabric with a low hydraulic conductivity can be obtained.

  In the spun bonding method, the thickness of the non-woven fabric becomes thin and the water permeability coefficient becomes low because the fibers are thermocompression-bonded to each other. Therefore, it is suitable for preparation of the second water-permeable layer 22. The heat transfer coefficient can be adjusted by the amount of heat of thermocompression bonding.

The first water permeable layer 21 and the second water permeable layer 22 are integrally joined and integrated.
The second water-permeable layer 22 and the third water-permeable layer 23 are integrally joined and integrated.
The water permeable layers 21, 22, 23 may be integrally manufactured by driving the felt needles while sequentially laminating the fibers to be the water permeable layers 21, 22, 23 by the needle punching method.

The third water-permeable layer 23 and the water-impermeable sheet portion 10, and hence the water-permeable sheet portion 20 and the water-impermeable sheet portion 10, are integrally or partially integrated integrally, except for the side end portions. The side ends of the water-permeable sheet portion 20 and the water-impermeable sheet portion 10 are free (non-bonded) for addition with the leading or trailing waterproof sheet 5.
When the waterproof sheet 5 having a four-layer structure is expanded by joining and integrating the three water-permeable layers 21, 22, and 23 entirely, it is possible to work in the same manner as a conventional two-layer waterproof sheet.

The method for joining the water impermeable sheet portion 10 and the water permeable sheet portion 20 is not particularly limited, and a known bonding method can be applied. For example, a hot melt adhesion method may be applied. That is, the hot melt resin and the hot air are provided between the water impermeable sheet portion 10 and the water permeable sheet portion 20, and a part of the opposing surfaces of the water impermeable sheet portion 10 and the third water permeable layer 23 is melted. Further, the water impermeable sheet portion 10 and the water permeable sheet portion 20 are pressure-bonded to be joined.
The water impermeable sheet portion 10 and the water permeable sheet portions 20 may be integrally joined by an adhesive other than the hot melt adhesive.

The tunnel 1 is constructed as follows.
As shown in FIG. 1, the ground 2 is excavated, and the blast concrete 3 is sprayed on the ground excavated surface 2 a.
Next, the waterproof sheet 5 is stretched on a form (not shown) along the inner peripheral wall 3 a of the shot concrete 3. A gap 4 a is provided between the waterproof sheet 5 and the shot concrete 3. The water-permeable sheet portion 20 of the waterproof sheet 5 is made to face the shot concrete 3 through the gap 4 a. The water impermeable sheet portion 10 is directed to the formwork.

Next, the space 4a is filled with the mortar 4b (backfill material) to be the primary lining 4. At this time, the mortar 4 b can easily enter the highly permeable first water permeable layer 21. On the other hand, the mortar 4 b can not easily enter the low water permeability second permeable layer 22. Thereby, the mortar 4 b can be prevented or suppressed from entering the third water permeable layer 23. Therefore, clogging of the third water permeable layer 23 can be prevented.
During curing of the mortar 4b, the water in the mortar 4b is discharged to the outside through the water permeable sheet portion 20. As a result, the water-cement ratio W / C of the mortar 4b can be reduced to improve the quality.

Soon, the mortar 4b solidifies. The mortar 4 b which has entered the first water permeable layer 21 also solidifies. Thereby, the primary lining 4 and the waterproof sheet 5 can be firmly fixed.
Furthermore, the second lining 6 is constructed.

In the tunnel 1, when spring water from the ground 2 penetrates through the primary lining 4 to the waterproof sheet 5, the impermeable sheet 10 can prevent water permeation to the secondary lining 6. Instead, the permeable sheet portion 20 can be drained as a drainage channel. In particular, the third water-permeable layer 23 of the water-permeable sheet portion 20 can be reliably functioned as a drainage and drained.
For example, when a hair crack is formed to reach the waterproof sheet 5 across the primary lining 4 due to drying shrinkage, earthquake, etc., the hair crack becomes a passage of spring water, so that the waterproof sheet 5 is damaged. Water pressure is applied. When the water pressure exceeds a certain level, spring water permeates through the second water permeable layer 22 in the thickness direction and flows into the third water permeable layer 23. As a result, the third water permeable layer 23 can be reliably drained as a drainage channel.
Furthermore, when solid components, such as earth and sand and lime, are mixed in the spring water, the solid components can be captured by the second water permeable layer 22. Therefore, the clogging of the third water permeable layer 23 can be prevented or suppressed for a long period of time, and the drainage function can be reliably maintained.

The present invention is not limited to the above embodiment, and various modifications can be made without departing from the scope of the invention.
For example, the waterproof sheet 5 may be used as a waterproof sheet of an old tunnel such as the NATM method. In the conventional tunnel construction method, the waterproof sheet 5 may be fixed to the primary lining by fixing means such as nails.
The first water permeable layer 21 may have water permeability to such an extent that the mortar 4 b (backfill material) penetrates. The water permeability coefficient of the first water permeable layer 21 may be higher than the water permeability coefficient of the second water permeable layer 22, and may be lower than the water permeability coefficient of the third water permeable layer 23.

  The present invention is applicable to, for example, a waterproof structure of the inner wall of a tunnel.

Reference Signs List 1 tunnel 2 ground 2a ground excavated surface 3 shot concrete 3a inner circumferential wall 4 primary lining 4a gap 4b mortar (backfill material)
5 waterproof sheet 6 secondary lining 10 water impermeable sheet part 20 water permeable sheet part 21 first water permeable layer 22 second water permeable layer 23 third water permeable layer

Claims (2)

A tarpaulin provided between the primary lining and the secondary lining in the tunnel,
The water impermeable sheet portion facing the secondary lining, and a water permeable sheet portion laminated on the water impermeable sheet portion, the water permeable sheet portion being
A first permeable layer facing said primary lining;
A second permeable layer laminated to the first permeable layer;
A third water permeable layer laminated between the second water permeable layer and the water impermeable sheet portion;
A waterproof sheet having a water permeability lower than that of the first water-permeable layer and the third water-permeable layer.   The waterproof sheet according to claim 1, wherein a thickness of the second water-permeable layer is 0.03 times to 0.3 times a thickness of the water-permeable sheet portion.

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