JP2016183516A - Tunnel structure and tunnel construction method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To propose a tunnel structure and a tunnel construction method having the drainage function on a back face of lining concrete.SOLUTION: A tunnel structure 1 comprises spray concrete 21 for constituting a part of timbering 2, lining concrete 3, a waterproof sheet 5 for covering an outer surface of the lining concrete 3, a cushioning material layer 7 for covering an outer surface of the waterproof sheet 5, a backfilling material 4 filled between the cushioning material layer 7 and the spray concrete 21, and a drainage layer 6 formed between the cushioning material layer 7 and the waterproof sheet 5.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a tunnel structure and a tunnel construction method.

The NATM tunnel is generally configured by including shotcrete, a waterproof sheet stuck on the surface of the shotcrete, and lining concrete placed on the inner side of the waterproof sheet.
In general, the waterproof sheet is fixed to the surface of the shotcrete by hitting a large number of stoppers such as nails and scissors.
However, the work of fixing the waterproof sheet using the stopper is troublesome. In addition, when the overexcavated portion is large, the amount of lining concrete increases.

Therefore, in Patent Document 1, a waterproof sheet is disposed on the inner side of the shotcrete through a mold or the like, and after filling a backfill material in a gap between the waterproof sheet and the shotcrete, the waterproof sheet A tunnel construction method is disclosed in which lining concrete is cast on the inner air side of the door.
According to this tunnel construction method, it is easy to install the waterproof sheet, and the lining concrete can be constructed as designed by forming a smooth surface with the backfill material and the waterproof sheet.

Japanese Patent No. 4044719

In the tunnel formed by the tunnel construction method of Patent Document 1, if a crack occurs in the backfill material, the crack becomes water and spring water is accumulated on the back surface of the waterproof sheet, and the waterproof sheet may expand. Moreover, there is a possibility that spring water that has permeated from the joint of the backfill material may accumulate on the back surface of the waterproof sheet.
If the waterproof sheet expands due to spring water collected on the back before the lining concrete is constructed, it will hinder the construction of the lining concrete.
In addition, when the underground hydrostatic pressure is not taken into consideration when designing the lining concrete, problems arise in structural strength when spring water accumulates on the back surface after the construction of the lining concrete. Furthermore, even when groundwater rises due to the poor efficiency of the backside of the lining concrete, there is a problem in structural strength.

  An object of the present invention is to solve the above-described problems, and an object of the present invention is to propose a tunnel structure and a tunnel construction method having a drainage function on the back surface of lining concrete.

  In order to solve the above problems, a tunnel structure according to the present invention includes shotcrete, lining concrete, a waterproof sheet that covers the outer surface of the lining concrete, and a buffer layer that covers the outer surface of the waterproof sheet, A backfilling material filled between the cushioning material layer and the shotcrete and a drainage layer formed between the cushioning material layer and the waterproof sheet are provided.

According to such a tunnel structure, since the drainage layer is formed on the outer surface (rear surface) of the waterproof sheet, even if spring water is generated from the backfill material, the drainage layer can drain the water. Therefore, it can prevent that it accumulates on the back surface of a waterproof sheet by the flow of spring water or groundwater.
Moreover, since the buffer material layer is provided, clogging of the drainage layer can be prevented and spring water can be guided to the drainage layer.

In addition, the said drainage layer may be equipped with two different types of drainage channels.
Moreover, the said tunnel structure may be equipped with the 2nd drainage layer in the natural ground side rather than the said buffer material layer.
According to such a tunnel structure, spring treatment can be performed more effectively.
Examples of the second drainage layer include a drainage drain that covers the end of the rock bolt, a drain that covers the joint of the backfill material, and the like.

Further, the tunnel construction method of the present invention includes a step of disposing a waterproof sheet with a gap from the inner surface of the shotcrete, a step of forming a drainage layer on the outer surface of the waterproof sheet, and a buffer on the outer surface of the drainage layer. A step of forming a material layer, a step of filling a backfill material between the shotcrete and the buffer material layer, and a step of placing lining concrete on the inner surface of the waterproof sheet. It is said.
According to such a tunnel construction method, a tunnel having a drainage function on the back surface of the lining concrete can be easily constructed.

  According to the tunnel structure and the tunnel construction method of the present invention, it is possible to construct a tunnel having a drainage function on the back surface of the lining concrete.

It is a cross-sectional view showing a tunnel structure according to an embodiment of the present invention. (A) is a typical expanded sectional view which shows a part of tunnel structure of FIG. 1, (b) is the longitudinal cross-sectional view. (A)-(d) is sectional drawing which shows each construction step of the tunnel construction method of this embodiment. It is a longitudinal cross-sectional view which shows a part of tunnel structure which concerns on 2nd embodiment. It is a longitudinal cross-sectional view which shows a part of tunnel structure which concerns on 3rd embodiment. It is a longitudinal cross-sectional view which shows a part of tunnel structure which concerns on another form.

<First embodiment>
As shown in FIGS. 1 and 2, the tunnel structure 1 according to the first embodiment includes a support 2, lining concrete 3, a backfill material 4, a waterproof sheet 5, a drainage layer 6, and a buffer. A material layer 7 and an invert 8 are provided.

The support work 2 is intended to stabilize the natural ground G by closing the natural ground G exposed by excavation at an early stage.
As shown in FIGS. 2 (a) and 2 (b), the support 2 of the present embodiment includes shotcrete 21, a steel support 22, and a lock bolt 23.
The shotcrete 21 is a hardened concrete that has been blown against the natural ground G. The shotcrete 21 is constructed so that the design shot thickness according to the ground level can be secured.

The steel support 22 is formed of an H-shaped steel formed in an arch shape according to the cross-sectional shape of the tunnel T, and as shown in FIG. 2B, at a predetermined interval with respect to the tunnel axis direction. It is arranged. The steel support 22 may set a cross-sectional dimension and an arrangement pitch according to the natural ground grade, and may be omitted depending on the natural ground grade.
As shown in FIG. 1, the lock bolts 23 are radially embedded in the natural ground G. The lock bolt 23 may be appropriately disposed as necessary, and may be omitted depending on the natural ground grade.
In addition, you may employ | adopt auxiliary construction methods, such as a receiving construction method, as the support construction 2 as needed.

As shown in FIG. 1, the lining concrete 3 is a hardened concrete cast on the inner side of the shotcrete 2, and forms a finished surface of the tunnel T and acts on the tunnel T for a long time. It functions as a structure with sufficient strength against load.
What is necessary is just to set the thickness of the lining concrete 3 suitably according to a natural ground grade.

As shown in FIGS. 2A and 2B, the backfill material 4 is formed of a cured body filled between the shotcrete 21 and the buffer material layer 7.
Although the material which comprises the backfilling material 4 will not be limited if it expresses predetermined intensity | strength by solidifying, In this embodiment, mortar is used.

The waterproof sheet 5 covers the outer surface of the lining concrete 3 to prevent the penetration of groundwater into the tunnel T. The waterproof sheet 5 may be disposed over the entire length of the tunnel T, or may be disposed only in a section where spring water is expected.
In the present embodiment, a resin sheet made of an ethylene vinyl acetate copolymer is used for the waterproof sheet 5, but the material constituting the waterproof sheet 5 is not limited.

The drainage layer 6 is interposed between the waterproof sheet 5 and the buffer material layer 7, and guides groundwater leached from the shotcrete 2 and the backfill material 4 to the lower side of the tunnel T.
The drainage layer 6 of the present embodiment is composed of a planar drainage material, and covers the outer surface of the waterproof sheet 5 in a section where a large amount of spring water is expected. The drainage layer 6 is continuous with respect to the circumferential direction of the cross section of the tunnel T, and groundwater leached from the shotcrete 2 and the backfilling material 4 is guided below the tunnel T by the drainage layer 6.

The drainage layer 6 (drainage material) is not limited as long as it is a member that can form a water-permeable space.
For example, the drainage layer may be constituted by a resin sheet on which a plurality of convex portions are formed. In this case, a convex part becomes a pillar and the space which can let groundwater flow around the convex part is formed.
Moreover, you may ensure water permeability by comprising with the drainage material of the three-dimensional network structure comprised with the fiber or the synthetic resin.
Furthermore, if it is composed of a face material (plate-like member) made of a material that dissolves with moisture, it will always form part of the lining with a predetermined strength, and partially dissolve during spring water. It is good also as what can be formed and can guide spring water below.
The drainage layer 6 does not necessarily need to be configured by a planar member, and may be formed by, for example, an arched perforated tube 61 interposed between the waterproof sheet 5 and the buffer material layer 7. (See FIG. 6). The installation location of the perforated pipe 61 is not limited. For example, the perforated pipe 61 may be piped at a predetermined pitch along the tunnel axis direction, or may be piped near the steel support 22 or the lock bolt 23. Alternatively, piping may be provided along the joining surface of the backfill material 4.

As shown in FIGS. 2A and 2B, the buffer material layer 7 is formed of a nonwoven fabric that covers the outer surface of the waterproof sheet 5. The buffer material layer 7 may be formed over the entire length of the tunnel, or may be formed only in the range where the drainage layer 6 is formed. The layer thickness of the buffer material layer 7 is set as appropriate.
The buffer material layer 7 prevents the mortar (backfill material 4) from penetrating into the drainage layer 6 and also serves as a buffer material for the pressure when the backfill material 4 is injected and the pressure when placing the lining concrete 3. Also works. That is, the buffer material layer 7 ensures the water flow function of the drainage layer 6 by preventing the drainage layer 6 from being clogged by the injection of the backfill material 4 and the drainage layer 6 being crushed. Moreover, when the drainage layer 6 is comprised by the perforated pipe etc. which were arrange | positioned by the predetermined space | interval, the buffer material layer 7 also exhibits the function which guide | induces spring water to a perforated pipe etc.
In addition, the material which comprises the buffer material layer 7 will not be limited to a nonwoven fabric, as long as it can permeate | transmit a water | moisture content while preventing the penetration | infiltration of the backfilling material 4. FIG. For example, a woven fabric or a sponge-like resin may be used.

The invert 8 is continuously formed on the leg portion of the lining concrete 3 to form a closed cross section, thereby increasing the proof stress of the tunnel T and preventing settlement and deformation.
The tunnel T may have a lower drainage layer (not shown) along the lower surface of the invert 8 as necessary.
In the case of forming the lower drainage layer, it is provided so as to be continuous with the drainage layer 6 so that the groundwater induced by the drainage layer 6 is drained through the lower drainage layer.

  The tunnel construction method of the present embodiment includes an excavation process, a primary lining process, a waterproof sheet disposing process, a drainage layer forming process, a buffer material layer forming process, a filling process, and a secondary lining process. It has.

The excavation step is a step of excavating the natural ground G to form a space having a predetermined cross-sectional shape in the ground.
The excavation method of the tunnel T is not limited, and mechanical excavation or blast excavation may be used.

  In the primary lining process, as shown in FIG. 3 (a), spray concrete 21 is sprayed on the ground surface exposed by excavation of ground ground G, steel support 22 is built, and lock bolt 23 This is the step of performing the placement. In the primary lining process, an auxiliary method may be applied according to the natural ground conditions.

  The waterproof sheet disposing step is a step of disposing the waterproof sheet 5 with a gap from the inner surface of the shotcrete 21 as shown in FIG. The waterproof sheet disposing process is performed after the tunnel excavation process in the excavation process and the support work 2 in the primary lining process are completed over the entire length of the tunnel, or after sufficient separation from the face.

The waterproof sheet 5 is installed on the surface of the formwork F disposed with a gap from the surface of the shotcrete 21 (surface on the inner air side). The formwork F may be supported by a slide center or a dedicated cart. In addition, the arrangement | positioning method of the waterproof sheet 5 is not limited, For example, you may arrange | position with a temporary support member.
The waterproof sheet 5 is disposed at a position covering the outer surface of the lining concrete 3. In addition, the formwork F is arranged at a position sufficiently separated from the shotcrete 21 (a position where a space where the waterproof sheet 5, the drainage layer 6, and the buffer material layer 7 can be secured) is arranged, and the outer surface of the waterproof sheet 5 The mold F may be moved to a predetermined position after the drainage layer 6 and the buffer material layer 7 are formed. In addition, the magnitude | size of the clearance gap between the waterproof sheet 5 and shotcrete 21 changes according to the amount of surplus digging at the time of excavation.

The drainage layer forming step is a step of forming the drainage layer 6 on the outer surface (surface on the ground mountain G side) of the waterproof sheet 5 as shown in FIG.
In the present embodiment, the drainage material is fixed to the outer surface of the waterproof sheet 5 in a state of being installed in the mold F. Although the fixing method to the waterproof sheet 5 of a drainage material is not limited, For example, what is necessary is just to adhere | attach with an adhesive agent.
The drainage layer 6 may be installed (laminated) on the outer surface of the waterproof sheet 5 in advance. If it does in this way, installation of drainage layer 6 will be completed with installation of waterproof sheet 5.

The buffer material layer forming step is a step of forming the buffer material layer 7 on the outer surface of the drainage layer 6 as shown in FIG.
The buffer material layer 7 is formed by fixing the nonwoven fabric to the drainage layer 6 or the waterproof sheet 5 with an adhesive or the like.
The buffer material layer 7 may be laminated on the outer surface of the waterproof sheet 5 together with the drainage layer 6 in advance. If it does in this way, installation of buffer material layer 7 will be completed with installation of waterproof sheet 4.

The filling step is a step of filling the backfill material 4 between the inner surface of the shotcrete 21 and the buffer material layer 7 as shown in FIG.
After filling the backfill material 4, the mold F is removed when a predetermined strength is developed in the backfill material 4. At this time, the buffer material layer 7, the drainage layer 6, and the waterproof sheet 5 are solidified in a state where a part of the backfill material 4 penetrates the buffer material layer 7, so that the surface of the backfill material 4 (on the inner side) Surface). A jig or the like for fixing the buffer material layer 7 to the backfill material 4 may be provided in advance.

The secondary lining process is a process of placing the lining concrete 3 on the inner surface of the waterproof sheet 5 as shown in FIG.
The lining concrete 3 is placed between a mold frame (slide centle) (not shown) and the waterproof sheet 4. The formwork is installed in a state where a predetermined gap (gap corresponding to the lining concrete thickness of the planned cross section of the tunnel) is opened from the waterproof sheet 4.
When a predetermined strength develops in the lining concrete 3, the formwork is removed.

Then, when the above excavation process, primary lining process, drainage layer forming process, waterproof sheet arranging process, filling process, and secondary lining process are repeated, a tunnel structure 1 having a predetermined extension is formed. The The tunnel structure 1 may be formed over the entire length of the tunnel T.
In this embodiment, after the construction of the lining concrete 3 proceeds to some extent, the construction of the invert 8 is performed behind the lining concrete 3 (at the wellhead side). The construction of the invert 8 may be performed after the construction of the lining concrete 3 is completed over the entire length of the tunnel.

As described above, according to the tunnel structure 1 and the tunnel construction method of the present embodiment, since the drainage layer 6 is formed on the outer surface (rear surface) of the waterproof sheet 5, spring water is generated from the backfill material 4. Also, the drainage layer 6 can drain water below the tunnel T. Therefore, it is possible to prevent the spring water from accumulating on the back surface of the waterproof sheet 5, and thus to prevent the construction of the lining concrete 3 from being hindered.
In addition, even when there is a time between filling the backfill material 4 and placing the lining concrete 3, spring water can be drained by the drainage layer 6. Work can be performed without requiring spring water treatment when placing concrete 3.
Since a sufficient drainage function is ensured by the drainage layer 6, the burden on the lining concrete 3 by the spring water can be reduced, and deterioration over time can be minimized.

Since the buffer material layer 7 is interposed between the drainage layer 6 and the backfill material 4, the drainage layer 6 can be prevented from being clogged, and the pressure and lining during the filling of the backfill material 4 can be prevented. It is possible to prevent the buffer layer 7 from absorbing the pressure at the time of placing the concrete 3 and the drainage layer 6 from being deformed.
Further, since the groundwater is guided to the lower side of the tunnel by the drainage layer 6, even when the groundwater penetrates the shotcrete 21 and the backfill material 4, the burden on the lining concrete 3 is small. Therefore, it is possible to prevent the lining concrete 3 from being cracked and the tunnel T from being deformed by the underground water pressure.

Moreover, since the lining concrete 3 is cast along the tunnel wall surface smoothly molded by the backfill material 4 and the waterproof sheet 5, the concrete amount of the lining concrete 3 is constant regardless of the amount of overburden. Therefore, the amount of concrete pouring does not increase due to construction errors and the like, which is economical and can form a tunnel lining with a planned uniform structure.
Moreover, since the waterproof sheet 5 is laid on the surface of the formwork F, compared with the case where the waterproof sheet 4 is installed on the surface of the shotcrete 2, the effort required for laying the waterproof sheet 4 can be reduced.

<Second Embodiment>
As shown in FIG. 4, the tunnel structure 1 according to the second embodiment includes a support 2, lining concrete 3, a backfill material 4, a waterproof sheet 5, a drainage layer 6, and a buffer material layer 7. And a second drainage layer 9.
Since the details of the supporting structure 2, the lining concrete 3, the backfill material 4 and the waterproof sheet 5 according to the tunnel structure 1 of the second embodiment are the same as the contents shown in the first embodiment, the detailed description is as follows. Omitted.

The drainage layer 6 is interposed between the waterproof sheet 5 and the buffer material layer 7, and guides groundwater leached from the shotcrete 21 and the backfill material 4 to the lower side of the tunnel T.
The drainage layer 6 of the present embodiment is composed of a plurality of perforated pipes 61 disposed at a predetermined interval with respect to the axial direction of the tunnel T. Each perforated pipe 61 is formed in an arch shape according to the cross-sectional shape of the tunnel.
In the present embodiment, as the perforated pipe 61 constituting the drainage layer 6, a pipe having a circular cross section is used, but the cross sectional shape of the perforated pipe 61 is not limited. It may be oval in cross section. Moreover, the drainage layer 6 does not necessarily need to be composed of a perforated pipe.

The buffer material layer 7 covers the outer surface of the waterproof sheet 5. The buffer material layer 7 may be formed over the entire length of the tunnel, or may be formed only in the section where the drainage layer 6 is formed. The layer thickness of the buffer material layer 7 is set as appropriate.
The buffer material layer 7 prevents the mortar (backfill material 4) from penetrating into the drainage layer 6 and also serves as a buffer material for the pressure when the backfill material 4 is injected and the pressure when placing the lining concrete 3. Also works. That is, the buffer material layer 7 prevents the drainage layer 6 from being clogged, the drainage layer 6 from being crushed, and the like. The buffer material layer 7 guides the groundwater leached from the backfill material 4 to the perforated pipe 61.

The second drainage layer (drainage drain) 9 is disposed closer to the natural ground G than the buffer material layer 7.
The second drainage layer 9 of the present embodiment is constituted by a drainage drain 9 having a U-shaped cross section. In addition, the cross-sectional shape of the drainage drain 9 is not limited, For example, semicircular shape may be sufficient.

The drainage drain 9 is formed in an arch shape according to the cross-sectional shape of the tunnel.
The drainage drain 9 is disposed at the position of the lock bolt 23 so as to cover the end of the lock bolt 23. Around the rock bolt, a space through which ground water can flow is formed by the drainage drain 9.
That is, the second drainage layer 9 is configured to guide the groundwater leached along the lock bolt 23 to the lower side of the tunnel.
In addition, the installation location of the drainage drain 9 is not limited. For example, the drainage drain 9 may be installed on the inner surface (surface on the inner air side) of the backfill material 4 so as to cover the joint surface of the backfill material 4. .

The tunnel construction method of the present embodiment includes an excavation process, a primary lining process, a drainage drain installation process, a waterproof sheet disposing process, a drainage layer forming process, a buffer material layer forming process, a filling process, And a next lining process.
The details of the excavation process and the primary lining process are the same as the contents shown in the first embodiment, and thus detailed description thereof is omitted.

The drainage drain installation process is a process of disposing the drainage drain 9 so as to cover the end of the lock bolt 23 after the primary lining process.
The drainage drain 9 is disposed in a state where the end surface is in contact with the shotcrete 21. A cushioning material is disposed on the end face of the drainage drain 9 as necessary to prevent a gap from being formed between the shotcrete 21 and the drainage drain 9.
In addition, the details of the waterproof sheet disposing step, drainage layer forming step, buffer material layer forming step, filling step and secondary lining step are the same as the contents shown in the first embodiment, so the detailed explanation is as follows. Omitted.

As described above, according to the tunnel structure 1 of the second embodiment, even when spring water that has permeated along the rock bolts 23 is generated, the drainage drain 9 can drain the water downward. Therefore, it is possible to prevent the spring water from accumulating on the back surface of the waterproof sheet 5, and thus to prevent the construction of the lining concrete 3 from being hindered.
Further, even when spring water is generated from the backfill material 4 due to a crack in the backfill material 4, the drainage layer 6 can drain the water downward. The spring water that has permeated the backfill material 4 is guided to the perforated pipe 61 by the buffer material layer 7 or taken into the perforated pipe 61 by flowing on the surface of the waterproof sheet 5, and below the tunnel T. And drained.
Since the operational effects of the tunnel structure 1 of the other second embodiment are the same as those of the tunnel structure 1 of the first embodiment, detailed description thereof is omitted.

<Third embodiment>
As shown in FIG. 5, the tunnel structure 1 according to the third embodiment includes a support 2, lining concrete 3, a backfill material 4, a waterproof sheet 5, a drainage layer 6, and a buffer material layer 7. Invert 8 is provided.
The details of the supporting structure 2, the lining concrete 3, the backfill material 4, the waterproof sheet 5, and the cushioning material layer 7 according to the tunnel structure 1 of the third embodiment are the same as the contents shown in the first embodiment. Detailed description will be omitted.

The drainage layer 6 of the third embodiment includes a perforated pipe 61 and a drainage drain 62.
The perforated tube 61 is a tube material through which a plurality of holes penetrates. A plurality of perforated pipes 61 are piped at intervals in the axial direction of the tunnel. The perforated pipe 61 is formed in an arch shape along the cross-sectional shape of the tunnel.

The drainage drain 62 has a U-shaped cross section and is arranged so that the opening is on the outside (the ground mountain G side). The drainage drain 62 is formed in an arch shape along the cross-sectional shape of the tunnel.
The drainage drain 62 is disposed so as to cover the joint location (joint surface 41) of the backfill material 4. The outer end face of the drainage drain 62 is in contact with the buffer material layer 7.
That is, the drainage drain 62 is configured to guide the groundwater leached along the joint surface 41 of the backfill material 4 to the lower side of the tunnel T.

  The configuration of the drainage layer 6 of the third embodiment is not limited as long as it includes two different types of drainage channels. For example, a planar drainage material and a perforated pipe or drainage drain are used. It may be a combination.

As described above, according to the tunnel structure 1 of the third embodiment, even if groundwater is leached along the joining surface 41, the drainage drain 62 can drain the water downward. Therefore, it is possible to prevent the spring water from accumulating on the back surface of the waterproof sheet 5, and thus to prevent the construction of the lining concrete 3 from being hindered.
Further, even when spring water is generated from the backfilling material 4 due to a crack in the backfilling material 4, the perforated pipe 61 can drain the water downward. The spring water leached from the backfill material 4 is guided to the perforated pipe 61 by the buffer material layer 7 or taken into the perforated pipe 61 by flowing on the surface of the waterproof sheet 5, and below the tunnel T. And drained.
Since the operational effects of the tunnel structure 1 of the other third embodiment are the same as those of the tunnel structure 1 of the first embodiment, detailed description thereof is omitted.

The embodiment according to the present invention has been described above. However, the present invention is not limited to the above-described embodiment, and the above-described components can be appropriately changed without departing from the spirit of the present invention.
For example, the cross-sectional shape of the tunnel is not limited, and may be, for example, a circular shape or a horseshoe shape.
Moreover, although the case where invert was formed was demonstrated in the said embodiment, invert should just be formed according to the excavation division of a tunnel, and does not necessarily need to form.

Moreover, the lining concrete, the waterproof sheet, the buffer material layer, the drainage layer, the buffer material layer, and the backfill material may be laminated in order from the inner space side.
Further, as shown in FIG. 6, the tunnel structure 1 may form the drainage layer 6 by piping a plurality of perforated tubes 61, 61,... Between the waterproof sheet 5 and the buffer material layer 7. . The cross-sectional shape of the perforated tube 61 is not limited to a circle, and may be a rectangle, for example. Further, instead of the perforated pipe 61, a bowl-shaped member (drainage drain) may be adopted. Moreover, the drainage layer 6 may have three or more different drainage channels.

DESCRIPTION OF SYMBOLS 1 Tunnel structure 2 Supporting work 21 Shotcrete 22 Steel support 23 Rock bolt 3 Covering concrete 4 Backing material 5 Waterproof sheet 6 Drainage layer 61 Perforated pipe (drainage channel)
62 Drainage drainage
7 Buffer layer 8 Invert 9 Second drainage layer (drainage drain)
F Formwork G Ground mountain T Tunnel

Claims (5)

Shotcrete,
Lining concrete,
A waterproof sheet covering the outer surface of the lining concrete;
A cushioning material layer covering the outer surface of the waterproof sheet;
A backfilling material filled between the cushioning material layer and the shotcrete;
A tunnel structure comprising a drainage layer formed between the buffer material layer and the waterproof sheet.   The tunnel structure according to claim 1, wherein the drainage layer includes two different types of drainage channels.   3. The tunnel structure according to claim 1, wherein a second drainage layer is provided closer to the ground than the buffer material layer.   The tunnel structure according to claim 3, wherein the second drainage layer covers an end of the rock bolt. Arranging a waterproof sheet with a gap from the inner surface of the shotcrete,
Forming a drainage layer on the outer surface of the waterproof sheet;
Forming a buffer layer on the outer surface of the drainage layer;
Filling a backfill material between the inner surface of the shotcrete and the buffer layer;
And a step of placing lining concrete on the inner surface of the waterproof sheet.

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