KR102593946B1 - A two-arch tunnel having a dedicate drainage case inside the upper girder of the central wall and its construction method - Google Patents

Abstract

In the present invention, when constructing a two-arch tunnel, the central wall is constructed after constructing the central tunnel (25), and the lining concrete (11) is constructed after excavating and constructing the main tunnel (10, 20). The upper girders on both sides of the central wall ( 30) and the construction joint 50 where the excavation surfaces of the left and right main tunnels 10 and 20 meet are located lower than the top end of the central tunnel and the top end of the main tunnel, so that the construction joint 50 on the left and right Groundwater generated at the top of the tunnel concentrates and collects, and as a result, water leakage always becomes a problem at the construction joint (100), which is the part where the upper girder (30) of the left and right central walls and the lining concrete (11) of the main tunnel meet. there is.
Regarding the drainage structure of the two-arch tunnel, which is vulnerable to such water leaks, a groundwater drainage case (150) is installed inside the upper girders (30) on both sides of the central wall, and a drain board (200) is installed on the left and right main tunnels (10, 20). ) and the waterproofing sheet 210 are inserted into the drainage case 150 and then the concrete linings 11 on the left and right sides of the main line are constructed, so that the water collected at the construction joint 50 where the central wall and the main line tunnel 10, 20 meet. Groundwater is completely guided inside the drainage-only case (150) and drained efficiently, completely blocking leaks and improving the constructability of the symmetrical 2-arch tunnel or asymmetrical 2-arch tunnel, making quality control of the central wall easy and future maintenance. It has the effect of reducing management costs.

Description

A two-arch tunnel having a dedicated drainage case inside the upper girder of the central wall and its construction method}

In the present invention, after excavating and constructing the central tunnel (25), a central wall consisting of a central wall foundation (45), a central wall (40), and a central wall upper girder (30) is constructed inside the central tunnel (25), After excavating and constructing the main tunnel (10, 20) on the left and right sides of the central wall, the central tunnel (25) is constructed in the 2-arch tunnel where the main tunnel concrete lining (11) structure is constructed on the left and right sides of the central wall girder portion (30). ) and the main line tunnel meet at a lower location than the ceiling of the central tunnel (25) and the main tunnel (10, 20), so groundwater generated at the top of the tunnel flows through the joint (50) to the upper girder of the central wall. In order to completely prevent water leakage occurring at the construction joint (100) where (30) meets the lining concrete (11) of the main tunnel, a drainage case (150) is installed inside the upper girder part (30) of the central wall. It relates to arch tunnels and their construction methods.

Figures 1, 2, and 3 show the construction of a conventional two-arch tunnel. First, the central tunnel 25 is excavated and constructed, then the foundation 45 and the central wall 40 of the central wall are constructed, and the central tunnel 25 is excavated and constructed. After constructing the upper girder (30) of the wall (40), the left and right main tunnels (10, 20) of the central tunnel (25) are excavated and constructed, and the lining concrete (11) is poured to complete the construction of the two-arch tunnel. It is common to do so.

Hereinafter, when it is referred to as a central wall without separate distinction, it is an expression referring to the commonly expressed name for the entire central wall foundation (45), central wall (40), and upper girder (30).

Figure 2 is an enlarged view of the upper part of the central wall (30) of a conventional two-arch tunnel, and shows the upper girder (30) of the central wall (40) constructed inside the central tunnel (25) after excavating and constructing the central tunnel (25). ) is connected to the ends of the lining concrete (11) of the left and right main tunnels (10, 20) on both sides.

The upper girder 30 of the two-arch tunnel has a trapezoidal lower sphere 30a in contact with the ends of the lining concrete 11 of the left and right main tunnels 10 and 20, and a fan shape formed on the top of the lower sphere 30a. It is constructed with the upper sphere (30b), and a construction joint (100) is created on the left and right sides of the central wall upper girder (30) where the ends of the left and right tunnel lining concrete (11) of the main tunnel (10, 20) meet. As a result, the junction 50 of the central tunnel 25 and the left and right main tunnels 10 and 20 is lower in height than the ceiling of the central tunnel 25 and the main tunnels 10 and 20, so that the upper part of the tunnel is attached to the junction 50. This is a part that is structurally vulnerable to water leaks, where groundwater generated from there collects and is discharged to the construction joint (100).

In order to prevent water leakage from the upper girder part 30 of the central wall 40, waterproofing construction of the joint 50, such as installing a longitudinal drain pipe 90, is complicated and difficult, so it is mainly used in the left and right main tunnels 10, Water leakage occurs through the construction joint 100 of the lining concrete 11 of 20).

Figure 3 is a perspective view of the longitudinal drainage perforated pipe 90 and the upper girder transverse drainage pipe 80, where the central tunnel waterproofing sheet 91 is installed and the central wall 40 and the central wall upper girder 30 are constructed. Later, the blasting and excavation work of the left and right main tunnels (10, 20) and the support materials (93) (see FIG. 2) of the left and right main tunnels (10, 20) are replaced with the central tunnel support materials (92) (see FIG. 2). There was a structural problem in that the waterproofing sheet 91 of the pre-constructed central tunnel was damaged when cutting the steel support 92 of the central tunnel 25 for connection.

In addition, in the construction joint 50 of the central tunnel 25 and the main tunnel 10, 20, the vertical drainage perforated pipe 90 is installed in the longitudinal direction of the tunnel, and then the upper girder horizontal drainage pipe 80 is installed. For this purpose, work such as cutting the waterproof sheet 91 and wrapping the drain pipe connection caused an additional vulnerable part to water leakage in the upper girder portion 30 of the 2 arch tunnel, causing a problem of additional water leakage.

The above-mentioned problem, water leakage of the upper girder 30 of the central wall of the 2-arch tunnel, leads to poor construction of the tunnel, subsequent defect repairs, poor tunnel traffic service, and increased maintenance costs, as well as technical problems of the 2-arch tunnel. This leads to problems that lead to distrust.

The problem to be solved by the present invention is to use a central tunnel ( 25) and the construction joints (50) of the left and right main tunnels (10, 20) are effectively drained to drain the central wall upper girder (30) and the lining concrete (11) of the left and right main tunnels (10, 20). To provide a water leak prevention method for the central wall upper girder (30) that completely blocks water leaks at the construction joint (100) where the meets, the central tunnel (25) excavation construction step; Central wall foundation (45) and wall construction (40) steps; Installation of the drainage case (150) and construction of the connected drain pipes (110, 140, 160); Central wall upper girder (30) construction stage; The technical task is the construction method of the two-arch tunnel, which is completed in the lining concrete construction stage for the left and right main tunnels (10, 20).

In order to achieve the above technical problem, the present invention installs a waterproofing sheet 91 at the ceiling end of the central tunnel 25 where it meets the upper surface of the upper girder 30 of the central wall 40, and then installs a waterproofing sheet 91 on the central wall foundation and ( 45) After constructing the central wall 40 and installing the drainage case 150 and drainage connection pipes 110, 140, and 160 (see Fig. 6) as shown in Fig. 5 inside the central wall upper girder 30. After completing the construction of the central wall by pouring concrete into the lower sphere (30a) of the upper girder (30) and the fan-shaped upper sphere (30b), the drain board (200) of the main tunnel (10, 20) and Open the groundwater blocking end 180 below the drainage inlet 250 (see Fig. 6a) of the drainage-only case 150, insert the waterproof sheet 210 to the bottom inside the case, and drain the drainage inflow of the open drainage-only case 150. A construction joint where the end of the upper girder 30 and the main tunnel lining concrete 11 meets by placing the drainage inlet 250 below the part 250 (see FIG. 6b) and then pouring the lining concrete 11. At (100), water leakage is completely prevented.

Groundwater flowing into the drainage-only case 150 is connected to a drain pipe 160 installed at an angle inside the central wall upper girder 30 installed in the longitudinal direction of the drainage-only case 150. This drain pipe 160 is used only for drainage. A drainage-only case (150) is installed inside the upper girder (30) of the central wall to ensure effective drainage by installing it at regular intervals within the case (150) and to make the subsequent construction of the two-arch tunnel simple and smooth. A two-arch tunnel and its construction method are provided.

In the first aspect of the present invention, after forming the central tunnel 25, a central wall is formed inside the central tunnel 25, and main tunnels 10 and 20 are formed on the left and right sides of the central wall. A two-arch tunnel construction method for forming an upper girder (30) on the upper part of the central tunnel (25) and the left and right main tunnels (10, 20) by attaching a waterproof sheet (91) to the upper end of the central tunnel (25). A step of extending and installing the waterproof sheet 91 up to the junction 50 with the excavation surface, and installing a drainage case 150, drain pipes 110, 160, and Inserting and installing a type drain pipe connector 140 and pouring concrete into the upper girder portion 30 so that the upper surface of the upper girder of the central wall is formed in contact with the ceiling of the central tunnel, and the inside of the upper girder 30 Open the drainage inlet 250 (see FIG. 6) of the drainage case 150 installed in the main line tunnel drain board 200 and waterproof sheet 210 to the inside floor of the case 150, then install the main line tunnel lining. It is characterized by comprising the step of forming concrete (11).

In another aspect of the present invention, the drainage-only case 150 installed inside the upper girder 30 of the central wall installed inside the central tunnel 25 includes the drainage inlet 250 of the drainage-only case 150 ( It is characterized as having a triangular cross-section with groundwater blocking ends (170, 180) bent at 90° outward on both sides and a drainage inlet (250) (see FIG. 6a).

In another aspect of the present invention, in order to install a drain pipe in the drainage-only case 150, a rubber packing 310 is installed inside the drainage-only case 150 where a hole 315 is made in the bottom of the drainage-only case 150. Insert the drain pipe connection body 300 with the insert in the outer direction of the drainage case 150, insert the rubber packing 311 into the connection body 300 from the outside of the drainage case 150, and fix the connection body 300. Shiki is completely adhered to the drainage case 150 with a female screw holder 320, connects the connection body and the drain pipe 160 with a drain pipe joint 330, and installs a drainage case on both sides of the central wall upper girder 30 ( The drain pipe 160 connected to 150) is connected to the Y-type drain pipe connector 140 to install a drain pipe 110 at a certain length in the lower part of the central wall upper girder 30, and to facilitate drain pipe maintenance at the lower part of the drain pipe. To do this, a water collection tank 120 is installed and a drain pipe 130 is connected to the lower part of the water collection tank.

In another aspect of the present invention, as an asymmetric two-arch tunnel construction method, the central wall installed inside the central tunnel 25 is installed spaced apart from the center of the central tunnel 25 on one side to form a structure between the central wall and the central tunnel. (25) It is characterized by having a drainage-only case (150) inside the upper girder (30) of the central wall, which is installed to allow movement and passage of construction engineers, transportation of construction materials, and passage of construction vehicles in the wide section between side walls. .

In the present invention, in a two-arch tunnel, a drainage-only case 150 of a triangular cross-section with a drainage inlet 250 (see Figure 6a) is installed inside the upper girder 30 and connected to the drainage-only case 150. After installing the inflow water discharge drain pipes (110, 1300, 160), complete the construction of the central wall, and then excavate and construct the main tunnel (10, 20), then drain board (200) and waterproofing installed in the main tunnel (10, 20). The sheet 210 passes through the drainage inlet 250 (see Figure 6a) and is inserted and installed to the bottom inside the drainage case 150, thereby sealing the central tunnel 25 and the left and right main tunnels 10 and 20. By effectively draining the groundwater that collects in the construction joint (50) and preventing groundwater from leaking into the construction joint (100), water leakage in the construction joint (100) can be more completely controlled, which causes defects in the two-arch tunnel. It has the effect of enabling active improvement of waterproofing methods.

The scope of the present invention is indicated by the claims described below rather than the detailed description above, and all changes or modified forms derived from the meaning and scope of the claims and their equivalent concepts should be construed as being included in the scope of the present invention. .

Figure 1 is a construction cross-sectional view of a conventional two-arch tunnel.
FIG. 2 is a detailed view of portion “A” of FIG. 1.
FIG. 3 is a detailed view of portion “A” of FIG. 1 and schematically shows the construction cross-section of FIG. 2.
Figure 4 is a construction cross-sectional view of the two-arch tunnel of the present invention.
FIG. 5 is a detailed view of portion “B” of FIG. 4.
Figure 6 is a detailed view of portion "C" of Figure 5.
FIG. 7 is a detailed view of portion “B” of FIG. 4 and schematically shows the construction cross-section of FIG. 5.
Figure 8 is an exploded perspective view of a drain pipe installed in a drainage-only case installed inside the upper girder of the central wall in portion "D" of Figure 6.
FIG. 9 is a construction flow chart including a drainage-only case installed inside the upper girder of the central wall in portion “B” of FIG. 4.
Figure 10 is a construction flow chart of a symmetrical two-arch tunnel according to the present invention.
Figure 11 is a construction flow chart of an asymmetrical two-arch tunnel according to the present invention.

With reference to the accompanying drawings, embodiments of the present invention will be described in detail so that those skilled in the art can easily implement it.

However, the present invention can be implemented in various different forms, and is not limited to the embodiments described herein. In order to clearly explain the present invention in the drawings, parts not related to the description have been omitted, and similar parts throughout the specification have been omitted. Similar reference numerals are given for .

As shown in Figure 4, in the construction of a two-arch tunnel, the central tunnel 25 is constructed first, and the central tunnel 25 is usually excavated and constructed using the NATM method by blasting. In this NATM method, when a tunnel excavation surface of a certain arch shape is formed by blasting, primary shotcrete (94) and support material (92) are poured and constructed on the tunnel excavation surface to establish the rock behavior of the original ground at an early stage and to install rock bolts (5). ) is radially inserted and installed into the original ground on the back of the tunnel excavation surface to prevent loosening of the ground around the tunnel excavation surface and secure the sealing effect between rock masses. Afterwards, the secondary support material 92 is installed on the tunnel excavation surface where the rock bolt 5 and the shotcrete 94 are formed to complete the central tunnel 25.

Here, when the central tunnel (25) is completed, the shotcrete (94) surface is cleaned as shown in FIG. 5, and then a waterproof sheet (91) is constructed between the upper part of the central wall upper girder (30) and the ceiling of the central tunnel (25). The first reason for installing the waterproof sheet (91) is to waterproof the upper ceiling part of the haunch of the central wall girder (30), and the second reason is to prevent water damage occurring at the upper ceiling part of the central wall girder (30). It is installed to guide groundwater to the drain board (200) and waterproof sheet (210) installed in the left and right main tunnels (10, 20).

The waterproof sheet 91 is arranged to extend to the construction joint 50 of the central tunnel 25 and the main tunnel 10, 20, and then the central wall foundation 45 and the central wall 40 are constructed, and the upper girder ( After placing the drain pipes (110, 140, 160) and the drainage case (150) inside the 30), the upper girder (30) is poured with concrete. When construction is completed, the lining concrete of the main tunnel (10, 20) is placed on the upper part of the central wall (25). The lower sphere (30a), which is the connection part of (11), and the upper sphere (30b), which is the upper ceiling part, are completed, and construction of the entire central wall is completed.

The left and right main tunnels (10, 20) of the central wall that have been completed inside the central tunnel (25) are also typically constructed using the NATM method by blasting. In this NATM method, when a tunnel excavation surface of a certain arch shape is formed by blasting, primary shotcrete (94) and support material (93) are cast and installed on the tunnel excavation surface to establish the behavior of the original ground rock at an early stage and to use rock bolts (6). ) is radially inserted and installed into the original ground on the back of the tunnel excavation surface to prevent loosening of the ground around the tunnel excavation surface and secure the sealing effect between rock masses. Afterwards, the secondary shotcrete (94) is installed on the formed tunnel excavation surface to complete the main tunnel excavation surface.

Next, the drainage inlet 250 (Figure Using the elasticity of the drainage-only case material (see 6a), it is opened downward to a certain width as shown in FIG. 6b, and the construction joint 50 of the central tunnel 25 and the main line tunnels 10 and 20 is approximately upper part of the main line tunnel side. Insert the drain board (200) from a height of 30 to 50 cm to the bottom inside the drainage case (150), and place the main tunnel (10, 20) waterproof sheets (210) side by side under the drain board (200) inside the drainage case (150). After inserting the drain board 200 and the waterproof sheet 210, insert it to the bottom and return the drain inlet 250 (see Figure 6a), which was opened to insert the drain board 200 and the waterproof sheet 210, to construct the waterproof sheet 210 of the main tunnel 10, 20. After completion, the lining concrete (11) of the left and right main tunnels (10, 20) is poured and constructed to complete the two-arch tunnel as shown in Figure 4.

Here, when installing the support material 93 in the main tunnel (10, 20), the support material 93 of the main tunnel (10, 20) is connected to the support material 92 of the central tunnel 25, and secondary shotcrete is poured to achieve the final result. 2 The excavated section of the arch tunnel will be completed. At this time, the waterproofing sheet 91 previously installed at the top of the central tunnel 25 was damaged due to structural problems due to work such as blasting and construction of the main tunnel 10 and 20 and cutting and connecting support materials 92 and 93. This occurs. Even if damage occurs in this way and a water leak occurs, the leaked groundwater flows downward and is guided to the waterproof case 150 and discharged outside through the drain pipes 110, 140, and 160.

The entire structure of the central wall, including the central wall and the upper girder (30), is an underground or underwater structure, and the reinforcing bar covering thickness is applied at 60 mm or more, so that ground water is discharged regardless of damage to the waterproof sheet (91) through the above operation at the construction connection portion (50). This is a case dedicated to drainage of groundwater coming down from the upper part of the tunnel with the drain board 200 and waterproof sheet 210 constructed in the main tunnels 10 and 20 described above through the drainage inlet 250 (see FIG. 6). It is derived as (150).

In particular, even if there is groundwater flowing between the central wall upper girder 30, the main tunnel 10, 20 lining concrete 11 and the waterproof sheet 210, the drainage inlet 250 of the drainage case 150 (Figure 6a) (Reference), the groundwater blocking ends (170, 180) bent at 90 degrees on both sides are inserted into the concrete of the lower sphere (30a) of the upper girder (30) of the central wall and the lining concrete (11) of the main tunnel (10, 20). Due to the groundwater blocking ends (170, 180), groundwater is induced into the drainage-only case (150) by passing through the drainage inlet (250) (see FIG. 6B).

The installation of the drainage case (150) and the drain pipes (110, 140, 160) is performed by considering the installation of the drainage case (150) and the drain pipes (110, 140, 160) when placing the reinforcement of the central wall upper girder (30). A drain pipe with rubber packing 310 is connected inside the drainage case 150 as shown in FIG. Insert the main body 300 toward the outside of the drainage-only case 150, insert the rubber packing 311 into the connection main body 300 from the outside of the drainage-only case 150, and secure the connection main body 300 with a female screw holder ( 320), it is completely adhered to the drainage case 150 and fixed as shown in FIG. 6, and then the connection body and the drain pipe 160 are connected with the drain pipe fitting 330 of FIG. 5.

In order to install a drain pipe in the drain-only case 150, a drain pipe connection body 300 with a rubber packing 310 inserted inside the drain-only case 150 is placed in a hole 315 in the bottom of the drain-only case 150. Insert the drain-only case (150) in the outer direction, insert the rubber packing (311) into the connection body (300) from the outside of the drainage-only case (150), and use the female screw holder (320) to secure the connection body (300) for drainage use only. It is completely adhered to the case 150, connects the main body and the drain pipe 160 with a drain pipe joint 330, and connects the drain pipe 160 to the drainage case 150 installed on both sides of the upper girder 30 of the central wall. A drain pipe 110 is installed at a certain length in the lower part of the central wall upper girder 30 by connecting it with a Y-type drain pipe connector 140, and a water collection tank 120 is installed at the lower part of the drain pipe to facilitate drain pipe maintenance. And connect the drain pipe 130 to the lower part of the water collection tank.

The drain pipe 160 connected to the drainage case 150 installed on both sides of the central wall upper girder 30 is connected with a Y-shaped connector 140 to form a drain pipe 110 of a certain length at the lower part of the central wall upper girder 30. ) is installed at the bottom of the drain pipe to facilitate maintenance of the drain pipe, and a water collection tank (120) is installed, and a drain pipe (130) is connected to the lower part of the water collection tank to form a drainage water collection well (41) at the upper part of the two-arch tunnel as shown in Figure 4. A two-arch tunnel with a drainage-only case 150 inside the upper girder of the central wall that completely discharges groundwater to the outside without leakage of the central wall and its construction method are provided.

Figure 9 (a) shows the construction stage of the central wall after construction of the central tunnel 25; (b) is a concrete pouring/construction step of installing the drainage case 150 and the drain pipe 110 on the upper girder 30 and then installing the upper girder lower body 30a; (c) is a step of installing a waterproof sheet (91) at the ceiling of the central tunnel and pouring/constructing concrete on the upper girder body (30b); (d) is the construction stage of connecting the central tunnel support (92) and the main tunnel support (93) after excavating and constructing the main tunnel (10, 20); (e) is the construction stage of the drain board (200) and waterproof sheet (210) of the main tunnel; (f) is a two-arch tunnel with a drainage case 150 inside the upper girder 30 of the central wall in the pouring and construction stage of the lining concrete 11 of the left and right main tunnels 10 and 20, and its construction flow chart. .

Figure 10 (a) shows the central tunnel 25 excavation and construction stage; In (b), after constructing the central wall foundation (45) and central wall (40) in the center of the central tunnel, the drainage case and drain pipe are connected inside the central wall upper girder (30), and then the upper girder lower sphere (30a) is constructed. step; (c) is the construction step of the upper girder upper body (30b); (d) is the excavation and construction stage of the right main tunnel (20); (e) is the excavation and construction stage of the left main tunnel (10); (f) is a two-arch tunnel with a drainage-only case 150 inside the central wall upper girder 30 constructed in the lining concrete 11 construction stage and its construction flow chart.

Figure 11 shows (a) the excavation and construction stage of the central tunnel 25; In (b), the central wall within the central tunnel 25 is spaced on one side at a certain distance from the center of the central tunnel 25, and after construction of the central wall foundation 45 and the central wall 40, drainage is placed inside the central wall upper girder 30. After connecting the dedicated case 150 and the drain pipes 110, 140, and 160, the upper girder lower sphere (30a) is constructed; (c) is the construction step of the upper girder upper body (30b); (d) is the excavation and construction stage of the right main tunnel (20); (e) is the excavation and construction stage of the left main tunnel (10); (f) is constructed at the lining concrete (11) construction stage, and the central wall is installed within the central tunnel (25) at a certain distance on one side from the center of the central tunnel (25), so that the space between the central wall and the side walls of the central tunnel (25) is maintained. A drainage case (150) is installed inside the upper girder (30) of the central wall, which has the effect of preventing safety accidents by expanding the work space by making it convenient for the movement and passage of construction engineers, transportation of construction materials, and passage of construction vehicles in a wide section. This is an asymmetric two-arch tunnel with and its construction flow chart.

5; Central tunnel rock bolt 6; Main line tunnel rock bolt 10: Main line left tunnel
11: Lining concrete 20: Main line right tunnel 25; central tunnel
30: Central wall upper girder 30a; Upper girder lower sphere 30b; Upper girder upper body
40: central wall 41; sump 45; Central wall foundation
50: junction 60, 140: Y-type drain connector 61; runoff drain pipe
70; Main tunnel floor concrete 80; Upper girder lateral drain pipe
90; longitudinal drainage perforated pipe 91; Waterproofing sheet on top of central wall
92; Central tunnel support material 93; Main tunnel Jibojae 94; shotcrete
100: construction joint 110, 130: drain pipe 120; catch basin
140; Y-type connector 150; Drainage only case 160; connector
170, 180; blocking end 200; Drain board 210: Waterproof sheet
300: Drain case and drain pipe connection main body 310, 311: Rubber packing
315; Case perforation 320: Connection body fixing female screw holder
330: Drain pipe fitting

Claims (4)

After forming the central tunnel 25, a central wall is formed inside the central tunnel 25, and an upper girder 30 is formed on the upper part of the central wall to form main tunnels 10 and 20 on the left and right sides of the central wall. In the two-arch tunnel construction method to form,
The waterproof sheet 91 is installed at the upper end of the central tunnel 25 by extending it to the junction 50 between the central tunnel 25 and the excavated surfaces of the left and right main tunnels 10 and 20. The steps and
Insert and install the drainage case 150, drain pipes 110, 160, and Y-type drain pipe connector 140 inside the left and right sides of the upper girder 30, and fill the upper girder portion 30 with concrete. Casting the upper surface of the upper girder (30) of the central wall to form contact with the ceiling of the central tunnel (25);
Open the drainage inlet 250 (see FIG. 6a) of the drainage case 150 installed inside the upper girder 30 and place the drain board 200 and waterproof sheet 210 for the main line tunnel on the inner floor of the case 150. It includes the step of forming the main tunnel lining concrete (11) after installation,
The drainage-only case 150 installed inside the upper girder 30 of the central wall has groundwater blocking ends bent at 90° outward on both sides from the drainage inlet 250 (see Figure 6a) of the drainage-only case 150 ( A two-arch tunnel construction method having a drainage-only case 150 inside the upper girder of the central wall, characterized by having a triangular cross-section with 170, 180) and a drainage inlet 250 (see FIG. 6a). delete In claim 1,
In order to install a drain pipe in the drain-only case 150, a drain pipe connection body 300 with a rubber packing 310 inserted inside the drain-only case 150 is drilled in a hole 315 in the bottom of the drain-only case 150. Insert the dedicated case 150 outward, insert the rubber packing 311 into the connection body 300 from the outside of the drainage case 150, and use the female screw holder 320 to secure the connection body 300 to the drainage only case. The connection body 300 and the drain pipe 160 are completely adhered to (150) and connected to the drain pipe joint 330, and the drain pipe 160 is connected to the drainage case 150 installed on both sides of the central wall upper girder 30. ) is connected to the Y-type drain pipe connector 140 to install a drain pipe 110 of a certain length in the lower part of the central wall upper girder 30, and a sump 120 is installed at the lower part of the drain pipe to facilitate drain pipe maintenance. A two-arch tunnel construction method having a drainage-only case (150) inside the central wall upper girder (30), characterized by installing and connecting a drain pipe (130) to the lower part of the water collection tank and connecting it to the water collection well (41). In the two-arch tunnel construction method according to claim 1,
The central wall installed inside the central tunnel 25 is installed spaced apart from the center of the central tunnel 25 to one side to allow movement and passage of construction engineers and transportation of construction materials in the wide section between the central wall and the side walls of the central tunnel 25. , A two-arch tunnel construction method characterized by having a drainage-only case 150 inside the upper girder of the central wall installed to allow passage of construction vehicles.