JP2020101037A - Tunnel waterproof and drainage structure - Google Patents

Abstract

To make it easy to keep a covering portion of a waterproof sheet that covers a back surface drainage material in a gutter shape, in a waterproof and drainage structure at each corner portion formed between an arch part and a bottom part of a tunnel.SOLUTION: A waterproof sheet 10 is stretched along an inner peripheral surface of sprayed concrete 3. A back surface drainage material 20 is arranged in a corner portion 1c formed by a bottom part 1b and an arch part 1a of a tunnel 1. A lower portion of the waterproof sheet 10 is made to wrap around from a front side surface 20a of the back surface drainage material 20 to a back side surface 20c via a bottom side surface 20b, and is further folded back at the back side surface 20c and extended to an upper surface of the bottom part 1b. On the back side surface 20c of the back surface drainage material 20, a joining member that is joined to a non-woven fabric layer 12 of the waterproof sheet 10 is provided. Preferably, a planar fastener 30 is used as the joining member.SELECTED DRAWING: Figure 1

Description

The present invention relates to a waterproof and drainage structure in a tunnel, and particularly to a drainage prevention structure suitable for a NATM (New Austrian Tunneling Method) tunnel.

The arch portion of the NATM tunnel includes sprayed concrete sprayed on the excavated surface of the ground and a secondary lining constructed on the inner peripheral side thereof (see, for example, Patent Document 1). A waterproof sheet is provided between the shotcrete and the secondary lining. The waterproof sheet has a structure in which a nonwoven fabric layer is laminated on the back surface of a water impermeable sheet layer made of an impermeable resin such as EVA. The nonwoven layer faces the shotcrete and the impermeable sheet layer faces the secondary lining.
The spring water that has permeated the sprayed concrete from the ground is blocked from permeating to the secondary lining side by the impermeable sheet layer of the waterproof sheet, and flows through the nonwoven fabric layer to the tunnel bottom side.

A back surface drainage material (drain material) is arranged at a corner formed by a side edge of a bottom plate made of base concrete of a tunnel and a lower edge of an arch (see Patent Document 2, etc.). The back surface drainage material has a water passage space that serves as a passage for water and extends in the axial direction of the tunnel. A cross drainage pipe is connected to the bottom of the back drainage material. The spring water that has passed through the nonwoven fabric layer is guided to the transverse drainage pipe through the inside of the back surface drainage material and is drained.

JP, 2017-57593, A Japanese Utility Model Publication No. 4-61196

At the corners between the arch part and the bottom part of the tunnel, water pressure is strongly applied by the spring water, and water leakage easily occurs. Therefore, it is recommended that not only the back drainage material is provided in the corner portion but also the back drainage material is wrapped with the waterproof sheet. Specifically, the waterproof sheet is wrapped around the front side surface of the back surface drainage material through the lower side surface to the back side surface, folded back at the back side surface, and extended to the top surface of the bottom plate portion. As a result, water leakage can be suppressed by folding the waterproof sheet into a gutter shape.

However, it is not easy to fold the waterproof sheet, and it is not easy to hold the waterproof sheet in a gutter shape because it tries to open due to elasticity. If a nail or tacker is hit to maintain the gutter shape of the waterproof sheet, holes will be made in the waterproof sheet and water will leak.
In view of the above circumstances, it is an object of the present invention to easily hold a portion of a waterproof sheet covering a back surface drainage material in a gutter shape in a drainage-proof structure in a corner portion between an arch portion and a bottom plate portion of a tunnel.

In order to solve the above problems, the tunnel water drainage structure according to the present invention,
A waterproof sheet including a water-impermeable sheet layer and a non-woven fabric layer laminated to each other, the non-woven fabric layer facing the sprayed concrete of the arch portion of the tunnel, and stretched along the inner peripheral surface of the sprayed concrete,
A corner drain formed by the side end of the bottom plate of the tunnel and the lower end of the arch, and a back surface drainage member arranged so as to extend in the axial direction of the tunnel,
The waterproof sheet covers the back surface drainage material so as to wrap around from the front side surface to the back side surface through the lower side surface, and further is folded back at the back side surface and extends to the top surface of the bottom plate portion,
A joining member that is joined to the non-woven fabric layer of the waterproof sheet is provided on the back side surface of the back drainage material.

According to this structure, when the waterproof sheet is stretched, when the waterproof sheet is folded into the back side surface of the back surface drainage material, the joining member is joined to the non-woven fabric layer at the folded portion of the waterproof sheet. As a result, the portion of the waterproof sheet covering the back surface drainage material is temporarily held in a gutter shape. After that, by pouring the secondary lining concrete, the waterproof sheet and the back surface drainage material are sandwiched between the sprayed concrete and the secondary lining, and the gutter shape of the waterproof sheet is reliably retained. As a result, drainage can be improved.

It is preferable that the joining member is a planar fastener.
The planar fastener is easily joined to the nonwoven fabric layer of the waterproof sheet.
The planar fastener may have hook-shaped raised hair or loop-shaped raised hair.
As the joining member, an adhesive or the like can be used in addition to the planar fastener.

It is preferable that the joining member is provided at each of a plurality of locations separated in the longitudinal direction of the back surface drainage material.
It is not necessary to provide the joining member continuously over the entire length of the back surface drainage material in the longitudinal direction. This can reduce material costs.

According to the present invention, in a drainage-proof structure in a corner portion between an arch portion and a bottom plate portion of a tunnel, the waterproof sheet can be easily held in a gutter shape that wraps the back surface drainage material.

FIG. 1 is a cross-sectional view of a NATM tunnel including a tunnel drainage structure according to an embodiment of the present invention. FIG. 2 is a cross-sectional view showing the circle II in FIG. 1 in an enlarged manner before the secondary lining concrete is poured. It is the perspective view which looked at the back surface drainage material of the above-mentioned tunnel prevention drainage structure from the shot concrete side.

An embodiment of the present invention will be described below with reference to the drawings.
As shown in FIG. 1, the NATM tunnel 1 includes an arch portion 1a having an upper arch-shaped cross section and a bottom plate portion 1b (invert) made of base concrete at the bottom. The arch portion 1a includes sprayed concrete 3 sprayed on the excavated surface 2a of the natural ground 2 and a secondary lining 4 constructed on the inner peripheral side thereof.
A waterproof sheet 10 is stretched along the inner peripheral surface of the shotcrete 3. The waterproof sheet 10 is sandwiched between the shotcrete 3 and the secondary lining 4.

As shown in FIG. 2, the waterproof sheet 10 includes a water impermeable sheet layer 11 and a non-woven fabric layer 12 that are laminated on each other. The impermeable sheet layer 11 is made of an impermeable resin such as EVA. The nonwoven fabric layer 12 is superposed on the back surface of the water impermeable sheet layer 11 and joined by heat sealing or the like. The non-woven fabric layer 12 faces the shotcrete 3 and the water impermeable sheet layer 11 faces the secondary lining 4 (FIG. 1).

As shown in FIG. 1, the back surface drainage material 20 (drain material) is arranged on each of the left and right sides of the tunnel 1 at the corner portions 1c formed by the side end portions of the bottom plate portion 1b and the lower end portion of the arch portion 1a. ing. The back surface drainage material 20 extends in a long shape along the axial direction of the tunnel 1 (direction orthogonal to the paper surface of FIG. 1 ).

As shown in FIGS. 2 and 3, the cross-sectional shape of the back surface drainage material 20 is formed into a substantially rectangular shape. Moreover, the long side of the cross section is oriented in the height direction. The height dimension of the back surface drainage material 20 (vertical dimension in FIG. 2) depends on the required drainage amount of the tunnel 1, but is, for example, about 200 mm to 500 mm, preferably about 300 mm. The thickness (size in the left-right direction in FIG. 2) of the back surface drainage material 20 is, for example, about 20 mm to 30 mm.

The back surface drainage material 20 includes a core material 21 and a water permeable filter 22. The core member 21 is composed of a plurality (a large number) of wire rods made of a hard synthetic resin such as polypropylene or polyethylene. These wire rods are wound in a loop shape or a spiral shape to form a three-dimensional net structure. The entire outer periphery of the core material 21 is covered with a water permeable filter 22. The water permeable filter 22 is composed of a mesh filter made of a synthetic resin such as polypropylene or polyethylene.
The core material 21 and the water permeable filter 22 form a water passage space 25 serving as a passage for water in the entire area of the back surface drainage material 20.
The water permeable filter 22 blocks the entry of dirt and sand into the water passage space 25.

As shown in FIG. 1, a transverse drainage pipe 5 and a drainage groove 6 are buried in the bottom plate portion 1b. The water passage space 25 of the back surface drainage material 20 is connected to the drainage groove 6 via the transverse drainage pipe 5.
In addition, in FIG. 2, illustration of the transverse drainage pipe 5 is omitted.

Furthermore, as shown in FIG. 2, the lower portion of the waterproof sheet 10 is covered with the back surface drainage material 20. Moreover, the back surface drainage material 20 is wrapped by the waterproof sheet 10. Specifically, the waterproof sheet 10 covers the back drainage material 20 from the front side surface 20a to the back side surface 20c via the lower side surface 20b. Further, the waterproof sheet 10 is folded back at the intermediate height of the back side surface 20c and extends to the upper surface of the bottom plate portion 1b.

As a result, the waterproof sheet 10 is folded into a gutter shape. In other words, the lower part of the waterproof sheet 10 forms the gutter 40. The gutter 40 includes a front gutter wall portion 41, a gutter bottom portion 42, and a back gutter wall portion 43. The front side gutter wall portion 41 covers the front side surface 20 a of the back surface drainage material 20. The gutter bottom portion 42 is laid on the bottom portion of the back surface drainage material 20. The back gutter wall portion 43 is sandwiched between the back side surface 20 c of the back surface drainage material 20 and the shotcrete 3. The back surface drainage material 20 is housed inside the gutter 40.

A folded-back portion 13 of the waterproof sheet 10 is formed on an upper end portion of the back gutter wall portion 43. In the back side gutter wall portion 43 and the gutter bottom portion 42, the waterproof sheet 10 is doubled. The end portion of the waterproof sheet 10 extends from the trough bottom portion 42 to the inside of the tunnel (right side in FIG. 2) along the upper surface of the bottom plate portion 1b. The end portion is fixed to the bottom plate portion 1b by the concrete nail 7.

As shown in FIGS. 2 and 3, a planar fastener 30 (joint member) is provided on a lower side portion of the back side surface 20c of the back surface drainage material 20 from an intermediate height. The planar fastener 30 has a sheet portion 31 and a large number of raised hairs 32. The sheet portion 31 is bonded to the water permeable filter 22 of the back surface drainage material 20. As schematically shown in FIG. 2, the nap 32 may have a hook shape, a loop shape, a mushroom shape, or a mixture thereof.

As shown in FIG. 3, the planar fasteners 30 are provided at a plurality of locations separated in the longitudinal direction of the back surface drainage material 20, respectively. It is not necessary to provide the surface fastener 30 continuously over the entire length of the back surface drainage material 20 in the longitudinal direction. This can reduce material costs.

The height dimension (vertical dimension) of the planar fastener 30 is preferably about 1/3 to 1/2 of the height dimension (vertical dimension) of the back side surface 20c of the back surface drainage material 20. When the height dimension of the back surface drainage material 20 is about 300 mm, the height dimension of the planar fastener 30 is preferably about 100 mm to 150 mm.

As shown in FIG. 2, a large number of raised hairs 32 of the planar fastener 30 are intertwined with the nonwoven fabric layer 12 of the waterproof sheet 10 that constitutes the back gutter wall portion 43. As a result, the waterproof sheet 10 that constitutes the back gutter wall portion 43 is joined to the planar fastener 30 and, in turn, joined to the back surface drainage material 20.

The tunnel 1 is constructed as follows.
The ground 2 is excavated, and the sprayed concrete 3 is placed on the excavated surface 2a.
The waterproof sheet 10 is stretched along the inner peripheral surface of the sprayed concrete 3.
The back surface drainage material 20 is installed in the corner portion 1c.

In the step of tensioning the waterproof sheet 10, the lower end portion of the waterproof sheet 10 is covered with the back surface drainage material 20, and the back surface drainage material 20 is passed from the front side surface 20a through the lower side surface 20b to the back side surface 20c. It is folded back at and is extended to the upper surface of the bottom plate portion 1b. As a result, the waterproof sheet 10 is folded into a gutter shape, and a gutter 40 made of the waterproof sheet 10 is formed.
At this time, the nonwoven fabric 12 of the back gutter wall portion 43 and the planar fastener 30 of the back surface drainage material 20 are easily joined. By lightly pressing the back surface drainage material 20 from the front side (right side in FIG. 2) to the sprayed concrete 3 side, the nonwoven fabric 12 of the back side gutter wall portion 43 and the planar fastener 30 can be reliably bonded.
This allows the waterproof sheet 10 to be easily folded into the shape of the gutter 40. Furthermore, the shape of the gutter 40 can be reliably maintained.
The end portion of the waterproof sheet 10 is fixed to the bottom plate portion 1b by the concrete nail 7.

Then, the concrete of the secondary lining 4 is poured. As a result, the waterproof sheet 10 and the back surface drainage material 20 are sandwiched between the sprayed concrete 3 and the secondary lining 4, and the shape of the gutter 40 by the waterproof sheet 10 is reliably maintained.
Therefore, the sheet fastener 30 may be temporarily fixed to the waterproof sheet 10 at least until the concrete of the secondary lining 4 is placed.

In the tunnel 1 after service, the spring water that has permeated the sprayed concrete 3 from the natural ground 2 is prevented from permeating to the secondary lining 4 side by the impermeable sheet layer 11 of the waterproof sheet 10. The spring water flows through the nonwoven fabric layer 12 to the bottom side of the tunnel 1 as a passage. Further, the spring water that has passed through the nonwoven fabric layer 12 is guided to the transverse drainage pipe 5 through the inside of the back surface drainage material 20, and is drained.
At the corner portion 1c between the arch portion 1a and the bottom plate portion 1b of the tunnel 1, the water pressure due to the spring water becomes high. On the other hand, since the gutter 40 is formed by the waterproof sheet 10 in the corner portion 1c and the back surface drainage material 20 is accommodated in the gutter 40, the spring water 40 can be drained along the gutter 40. As a result, water leakage from the corner portion 1c can be suppressed.

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, as the joining member between the waterproof sheet 10 and the back surface drainage material 20, an adhesive or the like can be used in addition to the planar fastener 30.

INDUSTRIAL APPLICABILITY The present invention can be applied to, for example, a waterproof and drainage structure of a mountain tunnel.

1 Tunnel 1a Arch part 1b Bottom part 1c Corner part 2 Ground 2a Excavation surface 3 Shotcrete 4 Secondary lining 5 Cross drainage pipe 6 Drain groove 7 Concrete nail 10 Waterproof sheet 11 Water impermeable sheet layer 12 Nonwoven layer 13 Fold back Part 20 Back surface drainage material 20a Front side surface 20b Lower side surface 20c Back side surface 21 Core material 22 Water-permeable filter 25 Water-permeable space 30 Surface fastener (joint member)
31 seat part 32 raised part 40 gutter 41 front side gutter wall part 42 gutter bottom part 43 back side gutter wall part

Claims (3)

A waterproof sheet including a water-impermeable sheet layer and a non-woven fabric layer laminated to each other, the non-woven fabric layer facing the sprayed concrete of the arch portion of the tunnel, and stretched along the inner peripheral surface of the sprayed concrete,
A corner drain formed by the side end of the bottom plate of the tunnel and the lower end of the arch, and a back surface drainage member arranged so as to extend in the axial direction of the tunnel,
The waterproof sheet covers the back surface drainage material so as to wrap around from the front side surface to the back side surface through the lower side surface, and further is folded back at the back side surface and extends to the top surface of the bottom plate portion,
A tunnel drainage structure, wherein a joining member that is joined to the nonwoven fabric layer of the waterproof sheet is provided on the back side surface of the back surface drainage material. The tunnel drainage structure according to claim 1, wherein the joining member is a planar fastener. The tunnel water drainage structure according to claim 1 or 2, wherein the joining members are provided at a plurality of positions separated from each other in the longitudinal direction of the back surface drainage material.

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