JP2017166149A - Waterproof sheet for tunnel, and waterproof structure of tunnel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a waterproof sheet for a tunnel that offers drainage performance while securing adhesion with a backfill material.SOLUTION: A waterproof sheet 5 is stretched along primary lining 3 of a tunnel 1. A backfill material 4b is filled between the primary lining 3 and the waterproof sheet 5. Furthermore, secondary lining 6 is cast and the waterproof sheet 5 is tucked between the backfill material 4b and the secondary lining 6. The waterproof sheet 5 includes a water-impermeable sheet part 10 facing the secondary lining 6, and a water-permeable sheet part 20. The water-permeable sheet part 20 includes an adhesion layer 21 adhered on a lining layer 4, a water conveyance layer 22 comprising a net-like body 22x laminated on the adhesion layer 21, and a rear surface cushioning layer 23 laminated between the water conveyance layer 22 and the water-impermeable sheet part 10. The adhesion layer 21 has a thickness between about 2 mm and 5 mm and basis weight between about 200 g/mand 500 g/m.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a waterproof sheet in a tunnel, and in particular, is stretched along a primary lining of a tunnel and sandwiched between a backfill material filled between the primary lining and a secondary lining. It relates to a waterproof sheet.

  The construction of a conventional general mountain tunnel is performed according to the following procedure. First, a natural ground is excavated. Next, sprayed concrete is sprayed on the natural ground to construct a primary lining. In addition, rock bolts are placed in order to achieve the integration of shotcrete and natural ground, and the effect of sewing. A waterproof sheet is attached to the surface of the primary lining using nails or the like. Thereafter, a secondary lining is placed using a movable formwork. According to this tunnel, the waterproof sheet is interposed between the primary lining and the secondary lining, so that the spring water from the natural ground is prevented from flowing into the secondary lining.

  Patent Document 1 discloses a waterproof sheet applied to the conventional general tunnel method. This waterproof sheet is obtained by laminating a resin-impermeable sheet portion and a water-permeable sheet portion. The water-impermeable sheet part faces the secondary lining, and the water-permeable sheet part faces the primary lining. The water-permeable sheet portion has a three-layer structure in which a sheet-like network layer (water conducting layer) is sandwiched between two nonwoven fabric layers. According to the waterproof sheet of patent document 1, it can drain smoothly because a water-permeable sheet part becomes a passage of spring water. In particular, even if a large amount of earth and sand is contained in the spring water, the surface nonwoven fabric layer facing the primary lining can easily pass the earth and sand, and the central sheet-like net layer serves as a water conduit. The earth and sand can be discharged to the outside together with the spring water, and clogging is difficult for a long time. Therefore, the water-conducting function can also be exhibited for a long time with respect to the nonwoven fabric layer on the back side facing the water-impermeable sheet portion.

Patent Document 2 discloses a so-called “back smooth tunnel lining method” as an improved tunnel method. In this method, after the primary lining with shotcrete, a waterproof sheet is placed over the tunnel-shaped sheet formwork. Then, a backfill material such as mortar is filled in the gap between the primary lining and the waterproof sheet. After that, a secondary lining is placed.
The waterproof sheet for this construction method has, for example, a two-layer structure of a water-impermeable layer having PVA (polyvinyl alcohol) chemically bonded to the surface (such as graft polymerization) and a non-woven backside buffer layer. The impermeable layer is directed to the secondary lining and the back buffer layer is directed to the primary lining. A back buffer layer is secured to the backfill material.

Japanese Patent Laid-Open No. 01-111999 Japanese Patent No. 4108460

  In the conventional general tunnel method, the waterproof sheet may be pressed against the uneven surface of the primary lining surface and broken when the secondary lining is placed. If this happens, it will not be possible to stop the spring water from the natural ground.

On the other hand, in the back smooth tunnel lining method, the joining surface of the backfill material with the waterproof sheet becomes smooth, so the waterproof sheet becomes a backfill material by the pressure at the time of placing the secondary lining. Even if pressed, it is hardly broken. On the other hand, since the back-filling material such as mortar enters the back buffer layer made of nonwoven fabric in the waterproof sheet, the fixing property with the back-filling material is ensured, but the drainage performance is almost lost. Therefore, when spring water is confirmed during tunnel construction, drainage is secured by attaching a spring water treatment sheet from the spring location to the lower lining back water collector after the primary lining. After that, the waterproof sheet is stretched, the backfill material is filled, and the secondary lining is placed. However, due to fluctuations in the underground “water path” and groundwater level associated with the construction of the tunnel, the spring water passes through the joints for each construction span and cracks after solidification of the backfill material, etc., to the waterproof sheet. May reach. In that case, since the waterproof sheet has almost no drainage performance, there is a concern that the secondary lining is adversely affected such as being overloaded due to an increase in water pressure, and the long-term durability of the tunnel may be reduced. In addition, since the primary lining and the backfilling material need to be fixed, the spring treatment sheet cannot be attached to the entire area between the primary lining and the backfilling material. Actually, the extent to which a spring water treatment sheet having a width of about 600 mm is stretched at a 1 m pitch in the tunnel extension direction is the limit. Furthermore, when the water path fluctuates, there is a possibility of water coming out of a place other than the back of the spring treatment sheet. In that case, the drainage function is hardly ensured. There are also demands to reduce material costs.
In view of such circumstances, the present invention is a waterproof sheet used in a so-called back smooth tunnel lining method or the like (that is, a backfill that is stretched along the primary lining of the tunnel and filled between the primary lining and the primary lining). The purpose is to ensure that drainage performance is expressed while securing the adhesion performance with the back-filling material in the waterproof sheet sandwiched between the material and the secondary lining, and to prevent the material cost from increasing. .

The inventors have conceived of applying the waterproof sheet of Patent Document 1 to the back surface smooth tunnel lining method in order to solve the above problems. However, since the surface nonwoven fabric layer in the waterproof sheet of Patent Document 1 is presumed to have a basis weight that allows the earth and sand to pass through easily, it can easily pass the backfill material. When this backfill material flows into the sheet-like network layer and solidifies, the drainage function is lost by blocking the passage of spring water by the sheet-like network layer. Accordingly, the inventors have further conducted research and development to arrive at the present invention.
The present invention is a waterproof sheet that is stretched along a primary lining of a tunnel and is sandwiched between a backfilling material and a secondary lining filled between the primary lining,
A 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,
A fixing layer made of a non-woven fabric to which the backfill material can penetrate and fix;
A water-conducting layer made of a net-like body laminated on the fixed layer;
A back buffer layer made of a nonwoven fabric laminated between the water-conducting layer and the water-impermeable sheet portion;
Wherein the said anchoring layer has a thickness of 2 mm to 5 mm, basis weight is characterized by a ^{200g / m 2 ~500g / m 2} .

  According to this waterproof sheet, by setting the thickness and basis weight of the fixing layer (surface nonwoven fabric layer) within the above numerical range, it is possible to allow the backing material to enter the fixing layer when filling the backing material, In addition, the backfilling material can be stopped around the middle of the fixing layer in the thickness direction to prevent or suppress entry into the water guide layer. Furthermore, it is possible to prevent the material cost from increasing. Eventually, the backfill material solidifies, so that the fixing layer is fixed to the backfill material. On the other hand, it is possible to prevent the internal passage of the water guide layer from being clogged with the backfill material. As a result, the drainage performance can be reliably expressed while securing the adhesion to the backfill material. Furthermore, it is not necessary to provide the above-described spring treatment sheet between the primary lining and the backfilling material, and the primary lining and the backfilling material can be reliably fixed over the entire area. Therefore, it is possible to surely prevent the backfill material and the waterproof sheet from being peeled off, thereby improving safety. In addition, by using the waterproof sheet of the present invention, it is possible to provide a water guiding layer in the entire area between the backfilling material and the secondary lining, so that even if the water channel fluctuates, it is possible to ensure the drainage function. it can.

Basis weight of the water guide layer ^is preferably ^{300g / m 2 ~500g / m 2} . Thereby, the drainage performance can be ensured more reliably.

  According to the waterproof sheet of the present invention, the drainage performance can be reliably expressed in the entire waterproof sheet while ensuring the fixing performance with the backfill material. Furthermore, it is possible to prevent the material cost from increasing.

FIG. 1 is a front 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 II in FIG. FIG. 3 is a perspective view schematically showing a portion of several mm to several cm of the mesh body of the waterproof sheet. FIG. 4 is a cross-sectional view schematically showing a portion of several mm to several cm of the waterproof sheet. FIG. 5 is a longitudinal sectional view showing a schematic configuration of the apparatus used for filling the mortar of the first embodiment. 6 is a photograph at the time of evaluation observation of one sample (no. H) in Example 1. FIG. Fig.7 (a) is front sectional drawing which follows the VIIa-VIIa line | wire of the same figure (b) which shows schematic structure of the apparatus used for the drainage performance evaluation of Example 1. FIG. FIG.7 (b) is side surface sectional drawing which follows the VIIb-VIIb line | wire of the same figure (a).

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
As shown in FIG. 1, a natural ground 2 is excavated to form a tunnel 1. The tunnel 1 includes a primary lining 3, a lining layer 4, a waterproof sheet 5, and a secondary lining 6 from the natural mountain 2 side. A primary lining 3 is constructed along the natural ground excavation surface 2a. The primary lining 3 includes a steel support (not shown) and shotcrete 3b. A waterproof sheet 5 is stretched along the primary lining 3, and a lining layer 4 is formed between the primary lining 3 and the waterproof sheet 5. The lining layer 4 is made of a solidifying backfill material made of, for example, mortar 4b. A waterproof sheet 5 is fixed to the lining layer 4. Further, the secondary lining 6 is constructed so that the waterproof sheet 5 is sandwiched between the lining layer 4 and the secondary lining 6. The secondary lining 6 is made of reinforced concrete or unreinforced concrete.

  As shown in FIG. 2, the waterproof sheet 5 has a laminated structure of a water-impermeable sheet portion 10 and a 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 lining layer 4 side.

The impermeable sheet portion 10 has high water impermeability. Thus, it has a waterproof function that prevents the spring water from the natural 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) and polyolefin resin. Examples of the polyolefin resin include completely nonpolar polyolefin resins such as polyethylene (PE) and polypropylene (PP). Further, a modified polyolefin resin in which adhesion is imparted by graft polymerization of a polar group (carboxyl group) such as acrylic acid or maleic anhydride to PE or PP may be used. Preferably, the material of the water-impermeable sheet portion 10 is EVA. The thickness of the impermeable sheet portion 10 is preferably about 0.4 mm to 3.0 mm.

  The water-permeable sheet part 20 is laminated | stacked on the surface (upper surface in FIG. 2) which faces the lining layer 4 side in the water-impermeable sheet part 10. As shown in FIG. The water permeable sheet portion 20 has a fixing function with the lining layer 4, a drainage function, and a buffering function between the lining layer 4 and the shotcrete 3 b (or the ground 2) and the secondary lining 6. ing.

The water permeable sheet portion 20 includes a fixing layer 21, a water guide layer 22, and a back buffer layer 23. The surface fixing layer 21 faces the lining layer 4. A water guide layer 22 is laminated on the impermeable sheet portion 10 side (lower side in FIG. 2) of the fixing layer 21. A back buffer layer 23 is laminated between the water guide layer 22 and the water-impermeable sheet portion 10.
In FIG. 2, the thickness of each layer 10, 21, 22, 23 of the waterproof sheet 5 is exaggerated.

The fixing layer 21 is composed of a nonwoven fabric. The material of the nonwoven fabric of the fixing layer 21 is preferably a chemical fiber such as polyester, polypropylene, or polyethylene.
The thickness of the fixing layer 21 is preferably about 2 mm to 5 mm. Basis weight of the pinned layer ^{21, 200g / m 2 ~500g / m} 2 is preferably about. Density of the pinned layer ^21, 80kg / ^m 3 ^~120kg / m about ³ are preferred.
When the thickness of the fixing layer 21 is less than 2 mm and the basis weight is less than 200 g / m ² , the possibility that the mortar penetrates excessively increases. When the thickness of the fixing layer 21 is more than 5 mm and the basis weight is more than 500 g / m ² , the material cost increases.

  A part 4 b ′ of the mortar 4 b of the lining layer 4 enters the fixing layer 21 and is solidified. As a result, the fixing layer 21 and thus the waterproof sheet 5 and the lining layer 4 are fixed. The fixing layer 21 is responsible for fixing performance with the lining layer 4 in the waterproof sheet 5. The mortar 4 b ′ almost stops in the middle of the fixing layer 21 in the thickness direction, and hardly reaches the water guide layer 22.

  The water guide layer 22 has water conductivity and bears drainage performance in the waterproof sheet 5. As shown in FIG. 3, the water conveyance layer 22 is comprised by the net-like body 22x. The net-like body 22x includes a large number of linear bodies 22a, 22a. The material of the linear body 22a is, for example, a synthetic resin such as polyamide, polyester, polyethylene, or polypropylene. Each linear body 22a extends in a wavy manner, changing its direction irregularly in the thickness direction or in-plane direction of the waterproof sheet 5. A plurality of linear bodies 22a, 22a... Intersect each other. A large number of meshes 22b are formed by these linear bodies 22a, 22a. The intersecting portion 22c between the linear bodies 22a and 22a is joined by adhesion or welding.

Basis weight of the water guide layer ^{22, 300g / m 2 ~500g / m} 2 is preferably about. By setting the basis weight of the water guide layer 22 to 300 g / m ² or more, the drainage performance can be further enhanced. When the basis weight of the water guide layer 22 is more than 500 g / m ² , the material cost increases.
In FIG. 3, the thickness (diameter) of the linear body 22a is preferably about 0.5 mm to 3 mm. The size of the mesh 22b (the average distance between two adjacent intersections 22c, 22c) is preferably more than 0.5 mm to about 20 mm.

  As shown in FIGS. 3 and 4, the net-like body 22x is undulating when viewed in the order of several millimeters to centimeters. The waviness of the mesh-like body 22x is formed in the longitudinal direction (the left-right direction in FIG. 4) and the width direction (the direction perpendicular to the paper surface in FIG. 4) of the mesh-like body 22x.

  In FIG. 2, the back surface buffer layer 23 is comprised with the nonwoven fabric. The material of the nonwoven fabric of the back buffer layer 23 is preferably a chemical fiber such as polyester, polypropylene, or polyethylene. The back buffer layer 23 is responsible for the buffer performance of the waterproof sheet 5. That is, the secondary lining 6 is sufficiently cut off from the lining layer 4 and thus the natural ground 2 by the back buffer layer 23 mainly of the respective layers 10 and 21 to 23 of the waterproof sheet 5, or the restraint is eased. . The thickness of the back buffer layer 23 is preferably about 3 mm to 5 mm. If the thickness of the back buffer layer 23 is less than 3 mm, the buffer function cannot be achieved. When the thickness of the back buffer layer 23 exceeds 5 mm, the material cost increases.

The fixing layer 21 and the water guide layer 22 are joined and integrated over the entire surface.
The water guide layer 22 and the back buffer layer 23 are joined and integrated over the entire surface.
The back buffer layer 23 and the water-impermeable sheet portion 10, and thus the water-permeable sheet portion 20 and the water-impermeable sheet portion 10 are joined or integrated entirely or partially except for the side end portions. Although detailed illustration is omitted, the side end portions of the water-permeable sheet portion 20 and the water-impermeable sheet portion 10 are free (non-joined) for addition to the preceding or subsequent waterproof sheet 5.
The joining method of the layers 21, 22, 23, and 10 is not particularly limited, and a known joining method can be applied. For example, a hot melt bonding method may be applied.
The waterproof sheet 5 is substantially flat in the metric order. On the other hand, as shown in FIG. 4, when viewed on the order of several millimeters to several centimeters, since the net-like body 22x is undulating, the entire waterproof sheet 5 is also undulating.

The tunnel 1 is constructed as follows.
As shown in FIG. 1, the primary lining 3 is constructed by excavating the natural ground 2 and spraying spray concrete 3b on the natural ground excavation surface 2a.
Next, a semi-cylindrical form (not shown) is installed along the inner peripheral wall 3 a of the primary lining 3.
The waterproof sheet 5 is carried into the tunnel construction site in a roll state. The end portion of the roll-shaped waterproof sheet 5 is clamped, fed out from one end portion in the circumferential direction of the tunnel-shaped (semi-cylindrical) mold, and stretched around the outer peripheral surface of the mold. At this time, the water-impermeable sheet portion 10 is applied to the outer peripheral surface of the mold, and the water-permeable sheet portion 20 is directed to the primary lining 3. Since the water-impermeable sheet portion 10 is undulated to such an extent that it does not affect the quality of the concrete (FIG. 4), only the convex portion is in contact with the outer peripheral surface of the mold. In short, the contact area between the water-impermeable sheet portion 10 and the outer peripheral surface of the mold is reduced. Therefore, the frictional resistance between the waterproof sheet 5 and the mold can be reduced during the stretching. As a result, the surface of the water-impermeable sheet portion 10 (contact surface with the mold) is hardly damaged. Moreover, it can prevent that the said clamp remove | deviates from the waterproof sheet 5, and can stretch the waterproof sheet 5 on a formwork smoothly.
In this way, the waterproof sheet 5 is stretched along the primary lining 3. A gap 4 a is formed between the waterproof sheet 5 and the primary lining 3. The fixing layer 21 is opposed to the primary lining 3 through the gap 4a.

  Next, the gap 4a is filled with mortar 4b (backing material). As shown in FIG. 2, a part 4 b ′ of the mortar 4 b enters the inside of the water permeable sheet portion 20. The mortar 4b 'penetrates from the surface of the fixed layer 21 to the middle of the thickness direction, and almost stops there. The water guide layer 22 is hardly reached. That is, by setting the thickness and basis weight of the fixing layer 21 within the above numerical range, the mortar 4b ′ can be allowed to enter the fixing layer 21, and the mortar 4b ′ passes through the fixing layer 21 in the thickness direction. It is possible to prevent or suppress entry into the water guide layer 22. Naturally, the mortar 4 b ′ can hardly enter the back buffer layer 23.

  During the curing of the mortar 4b, surplus 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 lowered and the quality can be improved, so that sufficient strength as a backfilling material can be surely exhibited.

Eventually, the mortar 4b solidifies. This mortar 4 b becomes the lining layer 4. The mortar 4 b ′ that has entered the water permeable sheet portion 20 is also solidified inside the fixing layer 21. Thereby, the lining layer 4 and the waterproof sheet 5 can be reliably fixed.
On the other hand, it is possible to prevent the inside of the water guide layer 22 from being clogged with the mortar 4b ′. Similarly, the back buffer layer 23 can be prevented from being clogged with the mortar 4b ′.

  Next, the concrete of the secondary lining 6 is laid. Here, the joint surface with the waterproof sheet 5 in the lining layer 4 is substantially smooth. Therefore, even if the waterproof sheet 5 is strongly pressed against the lining layer 4 by the pressure at the time of placing the secondary lining concrete, the water-impermeable sheet portion 10 is not torn. This can prevent the waterproof performance of the waterproof sheet 5 from being impaired.

In the tunnel 1, the spring water that has come out from the ground 2 through the shotcrete 3b penetrates into the waterproof sheet 5 through the joints for each construction span, cracks in the lining layer 4, and the like. When this occurs, the water-impervious sheet portion 10 can prevent water permeation to the secondary lining 6. Moreover, the water permeable sheet 20 can be drained as a drainage channel. In particular, since the water guide layer 22 of the water permeable sheet portion 20 is not clogged with the mortar 4b ′, it can function reliably as a drainage channel.
Compared to a waterproof sheet consisting of only two layers of a water-impermeable sheet portion and a non-woven fabric backside buffer layer, which is generally used in this type of tunnel conventionally, the waterproof sheet 5 having the water guiding layer 22 has a drainage performance. It can be significantly improved.
Furthermore, when solid components such as earth and sand or lime are mixed in the spring water, the solid components can be captured by the fixed layer 21. Therefore, clogging of the water guide layer 22 can be prevented or suppressed over a long period of time, and the drainage function can be sufficiently maintained.
In addition, the back surface buffer layer 23 can sufficiently cut the lining layer 4, and thus the shotcrete 3 b (or the ground 2), and the secondary lining 6. Or the restraint of the secondary lining 6 by the lining layer 4 and by the shotcrete 3b (or the natural ground 2) can be eased. Therefore, it is possible to prevent or suppress the occurrence of cracks in the secondary lining 6.

The present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.
For example, the backfilling material constituting the lining layer 4 is not limited to the mortar 4b, and may be a synthetic resin, an adhesive, or the like. The wire 22a of the mesh-like body 22x may be a metal wire or a resin-coated metal wire.

Examples will be described. The present invention is not limited to the following examples.
<Sample>
As shown in FIG. 5, samples 20X of a plurality of types (no. A to O in Tables 1 to 3) of water permeable sheets formed by laminating a fixing layer 21, a water guiding layer 22, and a buffer layer 23 were prepared.
(1) Adhering layer 21
A polyester non-woven fabric was used as the fixing layer 21 of each sample 20X.
The thickness of the fixing layer 21 of the sample 20X is 1.2 mm, 2.2 mm, 3.0 mm, 4.0 mm, 5.0 mm, and the basis weight is 120 g / m ² , 220 g / m ² , 300 g / m ^2. , 400 g / m ² and 500 g / m ² . The density of the fixed layer 21 was about 100 kg / m ³ .
(2) Water transfer layer 22
The basis weight of the water guide layer 22 of the sample 20X was three types: 250 g / m ² , 350 g / m ² , and 450 g / m ² . The material of the linear body 22a was polypropylene, and the diameter of the linear body 22a was about 0.8 to 0.9 mm.
(3) Back buffer layer 23
A polyester nonwoven fabric was used as the back buffer layer 23 of each sample 20X.
The thickness of the back buffer layer 23 of the sample 20X was 3 mm. This thickness is a lower limit thickness capable of maintaining the buffer performance of the back buffer layer 23.
(4) Size / Shape Each sample 20X was a rectangle of 300 mm length × 180 mm width.

The outer peripheral edge of each sample 20X was sealed with an aluminum adhesive sheet 39 over the entire periphery.
Each sample 20X was affixed to the inner peripheral surface of a vinyl chloride short tube 31 with an adhesive tape (not shown). By applying the buffer layer 23 to the inner peripheral surface of the short tube 31, the fixing layer 21 faces the internal space of the short tube 31.
Two samples 20X and 20X per one short tube 31 were provided 180 degrees apart.
The short pipe 31 had an inner diameter of 150 mm and a height of 400 mm.
The short pipe 31 was set up vertically and the lower end opening was closed with a cap 33.
Further, a straight pipe 32 made of vinyl chloride was vertically connected to the upper end portion of the short pipe 31. The inner diameter of the straight pipe 32 is the same as that of the short pipe 31, and the length of the straight pipe 32 is 1500 mm. Between the outer peripheral surfaces of the short pipe 31 and the straight pipe 32, the joint pipe 34 was straddled and sealed.

<Mortar placement>
From the upper end opening of the straight pipe 32, the mortar 4b was cast and filled into the short pipe 31 and the straight pipe 32.
The weight ratio of cement, sand and water in mortar 4b is
Cement: sand: water = 1: 3: 0.6.
In order to reproduce the discharge of surplus water from the mortar 4b, a small hole 31c is formed near the lower end of the peripheral wall of the short pipe 31, and the small hole 31c is covered by the lower side of the sample 20X. I did it.
The placement height of the mortar 4b was 1.5 m from the upper end of the sample 20X to the upper surface of the mortar 4b. The pressure applied to the sample 20X from the mortar 4b having this placement height corresponds to a value near the upper limit of the mortar placement pressure applied to the waterproof sheet in actual tunnel construction.
Four hours after the casting, the short tube 31 was removed, and the sample 20X was peeled off from the mortar 4b. In addition, it is considered that the mortar 4b after the lapse of 4 hours has almost lost the fluidity and the penetration phenomenon into the sample 20X is finished.

<Evaluation>
(1) Fixing performance The fixing layer 21 was visually observed for each sample 20X.
As a result, it was confirmed that the entire surface of the fixing layer 21 of all the samples 20X (no. A to O) was changed from the original white type to the black type, and that the mortar soaked in at least the fixing layer 21. It was. From this, it is thought that the fixing performance with respect to the mortar of these samples 20X is favorable.
(2) Penetration performance The back buffer layer 23 was visually observed for each sample 20X.
Sample no. About AC (thickness 1.2 mm of the adhering layer 21, basis weight 120 g / m ² ), a darkened portion was formed on the surface of the back buffer layer 23. In this part, since it is recognized that the mortar reaches the back buffer layer 23, these samples no. The penetration performance of A to C was determined to be excessive.
Sample no. As for D to F (thickness of fixed layer 21: 2.2 mm, basis weight: 220 g / m ² ), a slightly darkened portion is formed on the surface of back buffer layer 23, and the penetration performance was judged to be slightly excessive. . Compared with AC, there was little darkening, and the permeation performance was acceptable.
Sample no. G～O (pinned layer 21 having a thickness of 3 mm to 5 mm, a basis weight ^{300g / m 2 ~500g / m 2} ) for the darkening of the surface of the back buffer layer 23 is not observed too, penetration performance was good.
Therefore, it was confirmed that if the thickness of the fixing layer 21 is about 2 mm or more, or if the basis weight of the fixing layer 21 is about 200 g / m ² or more, both the fixing performance and the permeation performance (and drainage performance) can be achieved.
As shown in FIG. In H (the thickness of the fixing layer 21 is 3 mm, the basis weight is 350 g / m ² ), it was observed that the mortar soaked partway along the thickness direction of the fixing layer 21 and did not pass through the fixing layer 21.

(3) Drainage performance Two sample pieces 20x (FIG. 7) were obtained from each sample 20X by cutting the lower and upper portions of each sample 20X into 100 mm squares.
As shown to Fig.7 (a), each sample piece 20x was pinched | interposed between a pair of transparent acrylic standing boards 41 and 41. As shown in FIG.
As shown in FIG. 7 (b), the left and right side edges of the sample piece 20x were stopped by a pair of waterproof tapes 42,42. In addition, the pair of water-stopping tapes 42, 42 are extended to the upper and lower edges of the stand-up plate 41, so that a vertical and flat surface is provided between the pair of stand-up plates 41, 41 and the pair of water-stop tapes 42, 42. A clear water channel 43 was defined, and the sample piece 20x was interposed in the center of the water channel 43 in the vertical direction. Furthermore, as shown to Fig.7 (a), the upper part of the part which defines the said water channel 43 in each standing board 41 is cut diagonally, By the upper part rather than the sample piece 20x of the said water channel 43, A water inlet 43a that expands upward is provided. Furthermore, had been provided with a reference line L ₄ are the height of the middle portion of the water bowl opening 43a in the vertical plate 41. From the top edge of the sample piece 20x to the reference line _{L 4} it is, was 75 mm.
After the sample piece 20x was sandwiched between the pair of standing plates 41 and 41, the pair of standing plates 41 and 41 were pressurized in a direction approaching each other by the cylinder 44. The magnitude of the pressurization was 0.5 kg / cm ² . This value corresponds to the pressure applied to the waterproof sheet in the actual tunnel that has been constructed.
Water 500 ml was prepared in the measuring cup 45, and water was also prepared in another container (not shown).
While maintaining the pressurization, water in a separate container was poured into the water inlet 43a. Water was to exceed the reference line L _4. When it was confirmed that water dropped into the receiving container 46 below the water channel 43, water injection from another container was stopped.
Subsequently, a time when the water level of the water bowl opening 43a has reached the reference line L ₄ and the time of measurement initiation, the measurement since the start, the water w of the measuring cup 45 by continuously poured into water bowl opening 43a, water bowl the water level of the mouth 43a is to be maintained at a height of the reference line L _4.
And the time from the time of a measurement start to the time of measuring cup 45 becoming empty was measured.
The measurement results of the two sample pieces 20x and 20x of each sample 20X are averaged, and the hydraulic conductivity is calculated according to Darcy's law. cm ³ / min / m).
A result is shown in the column of the drainage performance of Tables 1-3. The numerical value in the same column is the water flow rate from both sides in the width direction of the tunnel.

[Comparative example]
As a comparative example, a mortar placement and drainage performance test similar to that of the sample 20X (no. A to O) of the above example was performed using a comparative sample made of only a nonwoven fabric having a thickness of 3 mm. The drainage performance, that is, the water permeation flow rate was 226.0 (cm ³ / min / m).
From the above results, it was confirmed that the drainage performance can be remarkably improved by making the water-permeable sheet portion 20 a three-layer structure of the fixing layer 21, the water guiding layer 22, and the back surface buffer layer 23.
Moreover, it was confirmed that the drainage performance can be sufficiently increased by setting the basis weight of the water guide layer 22 to 300 g / m ² or more.

  The present invention can be applied to a waterproof structure of an inner wall of a tunnel such as a railway or a road.

DESCRIPTION OF SYMBOLS 1 Tunnel 2 Natural mountain 2a Natural mountain excavation surface 3 Primary lining 3b Shotcrete 4 Lining layer 4a Crevice 4b Mortar (backing material)
4b 'Mortar in the fixing layer (backing material)
DESCRIPTION OF SYMBOLS 5 Waterproof sheet 6 Secondary lining 10 Water-impermeable sheet part 20 Water-permeable sheet part 21 Adhesion layer 22 Water conveyance layer 22a Linear body 22b Mesh | network 22c Intersection 22x Mesh-like body 23 Back surface buffer layer

Claims (2)

A waterproof sheet stretched along a primary lining of a tunnel and sandwiched between a backfill material and a secondary lining filled between the primary lining,
A 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,
A fixing layer made of a non-woven fabric to which the backfill material can penetrate and fix;
A water-conducting layer made of a net-like body laminated on the fixed layer;
A back buffer layer made of a nonwoven fabric laminated between the water-conducting layer and the water-impermeable sheet portion;
Wherein the said anchoring layer, a waterproof sheet having a thickness 2 mm to 5 mm, basis weight is characterized by a ^{200g / m 2 ~500g / m 2} . ^2. The waterproof sheet according to claim 1, wherein the basis weight of the water guiding layer is 300 g / m ^{2 to} 500 g / m ² .