Drainage system combining tunnel center deep buried ditch with tunnel main tunnel and construction method

Abstract

The present application relates to a tunnel center deep buried ditch and tunnel hole combination drainage system and construction method. At present, there is a lack of reliable center deep buried ditch and hole connection drainage system and its construction method. The present application includes an arch wall ring drainage blind pipe and an arch wall longitudinal drainage blind pipe, which are uniformly arranged between the initial support and secondary lining of the tunnel; a tunnel bottom ring drainage blind pipe, which is laid at the bottom of the inverted arch and is in communication with the arch wall ring drainage blind pipe and the arch wall longitudinal drainage blind pipe; a hand hole, which is arranged in the inverted arch and the filling layer along the longitudinal direction of the tunnel at intervals; and a vertical drainage blind pipe, which is arranged in the vertical drainage hole between the hand hole and the center deep buried ditch; the arch wall ring drainage blind pipe and the arch wall longitudinal drainage blind pipe are connected to the tunnel bottom ring drainage blind pipe after being collected, and the drainage in the tunnel hole is led to the center deep buried ditch through the collection path and the vertical drainage blind pipe. The present application can realize reliable, heat preservation and non-destructive connection of the pipe jacking method construction center deep buried ditch and hole drainage system.

Description

Technical Field

[0001] This invention relates to the field of drainage technology in tunnel engineering, specifically to a drainage system and construction method that combines a deep-buried water ditch in the center of the tunnel with the main tunnel. Background Technology

[0002] In cold region tunnel engineering, groundwater seepage and frost heave are key factors affecting the safety and operational stability of the lining structure. To prevent frost damage, the design of drainage systems in cold region tunnels generally follows the principle of "external drainage". That is, seepage water collected around the lining through circumferential and longitudinal drainage blind pipes should not enter the side ditches or central ditches inside the tunnel, but should be directly discharged into a deep-buried drainage structure set within a sufficient depth range under the tunnel. This ensures that the drainage system is below the frost line and prevents groundwater from freezing around the lining or in the drainage channel, which could lead to lining cracks, ice cones, ice columns and other diseases.

[0003] In traditional construction methods, the deep-buried drainage ditch in the center of the tunnel is usually excavated and lined simultaneously with the main tunnel. That is, a cast-in-place or precast concrete drainage ditch is set under the tunnel invert and a continuous drainage channel is formed along the longitudinal direction of the tunnel. However, this construction method has problems such as large construction interference, poor insulation conditions of the drainage path and complex connection structure.

[0004] In recent years, the construction of deep-buried drainage ditches using the pipe jacking method has gradually attracted attention. This method involves independently constructing longitudinal drainage culverts at a certain depth below the tunnel before or after the main tunnel excavation. This significantly reduces interference with the main tunnel construction and allows the drainage channels to be placed in deeper, more stable strata, improving frost protection. However, the connection between the deep-buried drainage culverts formed by the pipe jacking method and the main tunnel drainage system still faces technical bottlenecks. The transverse water guide pipe needs to be led out from the longitudinal blind pipe of the main tunnel, pass through the lining and surrounding rock, and connect to the pipe jacking culvert. This path is long and involves many interfaces, and there is currently a lack of reliable construction solutions for the connection.

[0005] Therefore, it is necessary to propose new measures to overcome the above-mentioned shortcomings. Summary of the Invention

[0006] The purpose of this invention is to provide a drainage system and construction method that combines a central buried drainage ditch with the main tunnel, so as to at least solve the current problem of the lack of a reliable drainage system and construction method that connects the central buried drainage ditch with the main tunnel.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] The drainage system, which combines a deep-buried central ditch with the main tunnel, includes:

[0009] Both the circumferential drainage blind pipes and the longitudinal drainage blind pipes of the arch wall are arranged between the initial support and the secondary lining of the tunnel.

[0010] The tunnel bottom circumferential drainage blind pipe is laid at the bottom of the invert arch and is connected to the arch wall circumferential drainage blind pipe and the arch wall longitudinal drainage blind pipe.

[0011] Handholes are spaced longitudinally along the tunnel in the invert and filling layer, and the circumferential drainage blind pipe at the tunnel bottom leads to the bottom of the handhole; and

[0012] A vertical drainage blind pipe is installed in the vertical drain hole between the handhole and the central buried water ditch, and is connected to the tunnel bottom circumferential drainage blind pipe through an insulated tee joint;

[0013] After the circumferential drainage blind pipe and the longitudinal drainage blind pipe of the arch wall converge, they are connected to the circumferential drainage blind pipe at the bottom of the tunnel. The drainage in the main tunnel is led to the central buried water ditch through this convergence path and the vertical drainage blind pipe.

[0014] Furthermore, the hand hole extends vertically through the inverted arch and the filling layer.

[0015] Furthermore, when the main tunnel is a TBM-constructed tunnel, the invert arch is a precast invert arch block.

[0016] Furthermore, a circumferential drainage channel is reserved at the bottom of the precast invert arch block, and the circumferential drainage blind pipe at the bottom of the tunnel is laid in the circumferential drainage channel.

[0017] Furthermore, when the main tunnel is constructed using the drill-and-blast method, the invert arch is a cast-in-place invert arch, and the circumferential drainage blind pipe at the bottom of the tunnel is laid at the base before the cast-in-place invert arch is poured.

[0018] Furthermore, the insulated tee connector is located at the bottom of the hand hole.

[0019] Furthermore, the vertical drainage hole is drilled downwards from the bottom of the hand hole and extends to the central buried water ditch.

[0020] The construction method for the drainage system combining the deep-buried water ditch in the center of the tunnel with the main tunnel, as described above, includes the following steps:

[0021] Before or during the construction of the main tunnel, a water ditch is buried deep in the center of the construction site below the main tunnel using the pipe jacking method.

[0022] When constructing the invert arch and filling layer of the main tunnel, handholes are reserved along the longitudinal direction of the tunnel at the designed intervals, and a circumferential drainage blind pipe is installed at the bottom of the invert arch.

[0023] Circumferential drainage blind pipes and longitudinal drainage blind pipes of the arch wall are laid on the initial support surface and collected through joints;

[0024] The collected drainage is directed to the bottom of the invert and connected to the tunnel bottom circumferential drainage blind pipe. The end of the tunnel bottom circumferential drainage blind pipe is then directed to the manhole.

[0025] Drill vertical drainage holes downwards at the manhole location until they penetrate into the central buried ditch, and install vertical drainage blind pipes in the vertical drainage holes.

[0026] An insulated tee connector is installed at the bottom of the manhole to connect the circumferential drainage blind pipe and the vertical drainage blind pipe at the bottom of the tunnel, thus completing the connection of the drainage system.

[0027] Furthermore, when the main tunnel is constructed using the TBM method, the invert is a precast invert block, and the bottom of the precast invert block is reserved with a circumferential drainage channel. Both the handhole and the circumferential drainage channel are formed and reserved together during the factory prefabrication stage of the precast invert block.

[0028] Furthermore, when the main tunnel is constructed using the drill-and-blast method, the invert arch is a cast-in-place invert arch, and the handhole is pre-formed by a preset template when the cast-in-place invert arch concrete and the filling layer concrete are poured.

[0029] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0030] This invention provides a drainage system and construction method that integrates a deep-buried drainage ditch in the center of a tunnel with the main tunnel. It is applicable to TBM and drill-and-blast tunnels. The system includes circumferential drainage blind pipes in the arch wall, longitudinal drainage blind pipes in the arch wall, circumferential drainage blind pipes at the tunnel floor, manholes, and vertical drainage blind pipes. The circumferential and longitudinal drainage blind pipes in the arch wall are positioned between the initial support and the secondary lining, optimizing the hierarchical convergence path of the arch wall and tunnel floor blind pipes. The circumferential and longitudinal drainage blind pipes in the arch wall first converge at the circumferential drainage blind pipe at the tunnel floor, which then leads to the bottom of the manhole. Finally, an insulated tee joint connects the circumferential drainage blind pipes at the tunnel floor. The drainage blind pipes are connected to the vertical drainage blind pipes, ultimately leading water into the central buried water ditch. During construction, the central buried water ditch is jacked up, and handholes are reserved during the main tunnel construction. Blind pipes of various levels are laid and connected. Through the handholes, holes are drilled downwards to the central buried water ditch and vertical drainage blind pipes are installed. At the same time, this invention clarifies the specifications of each pipe diameter and the dimensions of the jacking pipe sections. Combined with the reserved handholes, vertical drilling, and insulated tee connections, a reliable, insulated, and non-destructive connection between the central buried water ditch and the main tunnel drainage system is achieved using the pipe jacking method. It is especially suitable for external drainage of tunnels in cold regions, with convenient construction, efficient drainage, reliable anti-freezing, and strong applicability. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other embodiments can be obtained from these drawings without creative effort.

[0032] Figure 1 This is a cross-sectional view of Example 1;

[0033] Figure 2 This is a plan view of Example 1;

[0034] Figure 3 This is a cross-sectional view of Example 2;

[0035] Figure 4 This is a plan view of Example 2;

[0036] The diagram is labeled as follows:

[0037] 1-Circumferential drainage blind pipe of arch wall, 2-Longitudinal drainage blind pipe of arch wall, 3-Circumferential drainage blind pipe of tunnel bottom, 4-Handhole, 5-Vertical drainage blind pipe, 6-Central deep buried water ditch, 7-Initial support, 8-Secondary lining, 9-Vertical drainage hole, 10-Insulated tee joint, 11-Precast invert arch block, 12-Circumferential drainage channel, 13-Cast-in-place invert arch, 14-Tee joint, 15-Four-way joint. Detailed Implementation

[0038] To facilitate understanding of the present invention, a more complete description will be given below with reference to the accompanying drawings. Preferred embodiments of the invention are shown in the drawings. However, the invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the invention.

[0039] In the description of this invention, it should be understood that the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0040] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "setting" should be interpreted broadly. For example, they can refer to a fixed connection or setting, a detachable connection or setting, or an integral connection or setting. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0041] In the description of this invention, it should be understood that the method involves multiple steps and should not be construed as a limitation on the order of the steps. Technical solutions obtained by changing the order of steps when solving the same technical problem are also within the protection scope of this invention.

[0042] Example 1:

[0043] like Figure 1 and Figure 2 As shown, this embodiment provides a drainage system that combines the deep-buried drainage ditch in the center of the tunnel with the main tunnel, which can achieve efficient, heat-insulating and reliable connection between the circumferential and longitudinal drainage of the tunnel in cold regions and the deep-buried drainage ditch. This embodiment includes an arch wall circumferential drainage blind pipe 1, an arch wall longitudinal drainage blind pipe 2, a tunnel bottom circumferential drainage blind pipe 3, a manhole 4 and a vertical drainage blind pipe 5. The arch wall circumferential drainage blind pipe 1 and the arch wall longitudinal drainage blind pipe 2 are connected to the tunnel bottom circumferential drainage blind pipe 3 after being collected through a joint. The drainage in the main tunnel is led to the central deep-buried drainage ditch 6 through this collection path and the vertical drainage blind pipe 5.

[0044] Specifically, the central buried water ditch 6 is constructed using the pipe jacking method and is located below the main tunnel. The central buried water ditch 6 is made up of precast reinforced concrete pipe sections, with an inner diameter of 120cm and a wall thickness of 16cm.

[0045] In this embodiment, the circumferential drainage blind pipe 1 and the longitudinal drainage blind pipe 2 of the arch wall are both arranged between the initial support 7 and the secondary lining 8 of the tunnel.

[0046] The tunnel bottom circumferential drainage blind pipe 3 is laid at the bottom of the invert arch and is connected to the arch wall circumferential drainage blind pipe 1 and the arch wall longitudinal drainage blind pipe 2 through the tee joint 14 and the four-way joint 15. Specifically, the arch wall longitudinal drainage blind pipe 2 is not set at the construction joint, and only the tee joint 14 is needed for connection. In the middle section, the pipes are intersected and the four-way joint 15 is needed for connection.

[0047] Among them, the circumferential drainage blind pipe 1 of the arch wall is a Φ80WG blind pipe, while the longitudinal drainage blind pipe 2 of the arch wall and the circumferential drainage blind pipe 3 of the tunnel bottom are both Φ100WG blind pipes.

[0048] In this embodiment, the main tunnel is a TBM construction tunnel, and the invert is a precast invert block 11.

[0049] The bottom of the precast invert block 11 has a circumferential drainage channel 12. The dimensions of the circumferential drainage channel 12 are 110×120cm (width×depth). The circumferential drainage blind pipe 3 at the bottom of the tunnel is laid in the circumferential drainage channel 12 at the bottom of the precast invert block 11. The part of the circumferential drainage blind pipe 3 at the bottom of the tunnel that extends beyond the precast invert block 11 can be directly poured.

[0050] Specifically, the handholes 4 are spaced along the longitudinal direction of the tunnel in the precast invert block 11 and the filling layer, and the handholes 4 vertically penetrate the precast invert block 11 and the filling layer. The circumferential drainage blind pipe 3 at the bottom of the tunnel is led to the bottom of the handholes 4.

[0051] Among them, the handhole 4 is a cuboid with a circumferential width of 40cm, a longitudinal length of 30cm, and a vertical height equal to the thickness of the inverted arch and the filling layer.

[0052] Specifically, the vertical drainage blind pipe 5 is installed in the vertical drain hole 9 between the handhole 4 and the central buried water ditch 6, and the vertical drainage blind pipe 5 is connected to the tunnel bottom circumferential drainage blind pipe 3 through the heat-insulated tee joint 10.

[0053] Among them, the thermal insulation tee joint 10 is set at the bottom of the manhole 4. The vertical drainage hole 9 is drilled downward from the bottom of the manhole 4 and extends to the central buried water ditch 6. The diameter of the vertical drainage hole 9 is Φ160mm. The built-in vertical drainage blind pipe 5 is a Φ150WG blind pipe. After the tunnel bottom circumferential drainage blind pipe 3 and the vertical drainage blind pipe 5 are placed, they are connected in the manhole 4 through the thermal insulation tee joint 10. Since the manhole 4 is a weak point in cold protection, local insulation is strengthened through the thermal insulation tee joint 10.

[0054] In this embodiment, the circumferential drainage blind pipe 1 and the longitudinal drainage blind pipe 2 of the arch wall converge to the circumferential drainage blind pipe 3 at the bottom of the tunnel through the tee joint 14 and the four-way joint 15. The circumferential drainage blind pipe 3 at the bottom of the tunnel is then led to the bottom of the manhole 4 and connected to the vertical drainage blind pipe 5 through the heat-insulated tee joint 10, and finally the water is introduced into the central buried water ditch 6.

[0055] This embodiment is applicable to TBM tunnels. By clarifying the layout of the circumferential drainage blind pipe 1 and the longitudinal drainage blind pipe 2 of the arch wall between the initial support 7 and the secondary lining 8, the hierarchical convergence path of the arch wall and the circumferential drainage blind pipe 3 at the bottom of the tunnel is optimized. The specifications of each pipe diameter and the dimensions of the jacking pipe section are also clarified. Combined with the processes of reserved handholes, vertical drilling, and insulated tee connections, a reliable, insulated, and non-destructive connection between the deep buried water ditch in the center of the jacking method and the main tunnel drainage system is achieved. It is especially suitable for external drainage of tunnels in cold regions and has the advantages of convenient construction, efficient drainage, reliable anti-freezing, and strong applicability.

[0056] Example 2:

[0057] In this embodiment, the main tunnel is constructed using the drill-and-blast method. Figure 3 and Figure 4 As shown, the invert is a cast-in-place invert 13. The circumferential drainage blind pipe 3 at the bottom of the tunnel is laid at the base before the cast-in-place invert 13 is poured. The manhole 4 is set at intervals along the longitudinal direction of the tunnel in the cast-in-place invert 13 and the filling layer, and the manhole 4 is vertically connected to the cast-in-place invert 13 and the filling layer.

[0058] The remaining structure and principle are the same as in Example 1.

[0059] Example 3:

[0060] This embodiment provides a construction method for a drainage system that combines a deep-buried water ditch in the center of the tunnel with the main tunnel, applicable to TBM tunnels, and includes the following steps:

[0061] S1: Before or during the construction of the main tunnel, a water ditch 6 is buried deep in the center of the main tunnel using the pipe jacking method.

[0062] The main tunnel was constructed using the TBM method.

[0063] S2: When constructing the invert arch or filling layer of the main tunnel, reserve handholes 4 at the designed intervals along the longitudinal direction of the tunnel, and reserve a circumferential drainage channel 12 at the bottom of the invert arch. Install a circumferential drainage blind pipe 3 at the bottom of the tunnel in the circumferential drainage channel 12.

[0064] The invert arch is a precast invert arch block 11. The handhole 4 and the circumferential drainage channel 12 are formed and reserved together during the factory prefabrication stage of the precast invert arch block 11.

[0065] S3: Lay circumferential drainage blind pipe 1 and longitudinal drainage blind pipe 2 on the surface of the tunnel initial support 7, and collect the circumferential drainage blind pipe 1 and longitudinal drainage blind pipe 2 through tee joint 14 or four-way joint 15.

[0066] S4: The collected drainage is led to the bottom of the invert and connected to the tunnel bottom circumferential drainage blind pipe 3, and the end of the tunnel bottom circumferential drainage blind pipe 3 is led to the manhole 4.

[0067] S5: At the position of handhole 4, use a down-the-hole drill to drill a vertical drainage hole 9 downwards until it penetrates into the central buried water ditch 6. Install a vertical drainage blind pipe 5 in the vertical drainage hole 9.

[0068] S6: Install an insulated tee connector 10 at the bottom of the manhole 4, and connect the tunnel bottom circumferential drainage blind pipe 3 and the vertical drainage blind pipe 5 through the insulated tee connector 10 to complete the connection of the drainage system, so that the water collected in the tunnel main tunnel can be directly introduced into the central buried water ditch 6 through the drainage system.

[0069] Example 4:

[0070] This embodiment provides a construction method for a drainage system that combines a deep-buried water ditch in the center of the tunnel with the main tunnel section. It is applicable to drill-and-blast tunnels and includes the following steps:

[0071] S1: Before or during the construction of the main tunnel, a water ditch 6 is buried deep in the center of the main tunnel using the pipe jacking method.

[0072] The main tunnel was constructed using the drill-and-blast method.

[0073] S2: When constructing the invert arch or filling layer of the tunnel main tunnel, reserve handholes 4 along the longitudinal direction of the tunnel at the designed spacing, and install the tunnel bottom circumferential drainage blind pipe 3 at the base before the invert arch is poured.

[0074] The invert arch is a cast-in-place invert arch 13, and the handhole 4 is formed by pre-setting a template when pouring the cast-in-place invert arch 13 concrete and the filling layer concrete.

[0075] S3: Lay circumferential drainage blind pipe 1 and longitudinal drainage blind pipe 2 on the surface of the tunnel initial support 7, and collect the circumferential drainage blind pipe 1 and longitudinal drainage blind pipe 2 through tee joint 14 or four-way joint 15.

[0076] S4: The collected drainage is led to the bottom of the invert and connected to the tunnel bottom circumferential drainage blind pipe 3, and the end of the tunnel bottom circumferential drainage blind pipe 3 is led to the manhole 4.

[0077] S5: At the position of handhole 4, use a down-the-hole drill to drill a vertical drainage hole 9 downwards until it penetrates into the central buried water ditch 6. Install a vertical drainage blind pipe 5 in the vertical drainage hole 9.

[0078] S6: Install an insulated tee connector 10 at the bottom of the manhole 4, and connect the tunnel bottom circumferential drainage blind pipe 3 and the vertical drainage blind pipe 5 through the insulated tee connector 10 to complete the connection of the drainage system, so that the water collected in the tunnel main tunnel can be directly introduced into the central buried water ditch 6 through the drainage system.

[0079] The above examples illustrate the present invention only to aid in understanding it and are not intended to limit the scope of the invention. Those skilled in the art can make various simple deductions, modifications, or substitutions based on the principles of this invention.

Claims

1. A drainage system combining a deep-buried central ditch with the main tunnel, characterized in that: include: The circumferential drainage blind pipe (1) and the longitudinal drainage blind pipe (2) of the arch wall are both arranged between the initial support (7) and the secondary lining (8) of the tunnel. The tunnel bottom circumferential drainage blind pipe (3) is laid at the bottom of the invert arch and is connected to the arch wall circumferential drainage blind pipe (1) and the arch wall longitudinal drainage blind pipe (2); Handholes (4) are spaced along the longitudinal direction of the tunnel in the invert and filling layer, and the circumferential drainage blind pipe (3) at the bottom of the tunnel leads to the bottom of the handholes (4); and A vertical drainage blind pipe (5) is installed in the vertical drain hole (9) between the handhole (4) and the central buried water ditch (6), and is connected to the tunnel bottom circumferential drainage blind pipe (3) through a heat-insulated tee joint (10); After the circumferential drainage blind pipe (1) and the longitudinal drainage blind pipe (2) of the arch wall converge, they are connected to the circumferential drainage blind pipe (3) at the bottom of the tunnel. The drainage in the main tunnel is led to the central deep-buried ditch (6) through the convergence path and the vertical drainage blind pipe (5).

2. The drainage system combining a deep-buried central drainage ditch with the main tunnel as described in claim 1, characterized in that: The handhole (4) extends vertically through the inverted arch and the filling layer.

3. The drainage system combining a deep-buried central drainage ditch with the main tunnel as described in claim 1, characterized in that: When the main tunnel is a TBM-constructed tunnel, the invert arch is a precast invert arch block (11).

4. The drainage system combining a deep-buried central drainage ditch with the main tunnel as described in claim 3, characterized in that: The bottom of the precast inverted arch block (11) is reserved with a circumferential drainage channel (12), and the tunnel bottom circumferential drainage blind pipe (3) is laid in the circumferential drainage channel (12).

5. The drainage system combining a deep-buried central drainage ditch with the main tunnel as described in claim 1, characterized in that: When the main tunnel is constructed using the drill-and-blast method, the invert arch is a cast-in-place invert arch (13), and the circumferential drainage blind pipe (3) at the bottom of the tunnel is laid at the base before the cast-in-place invert arch (13) is poured.

6. The drainage system combining a deep-buried central drainage ditch with the main tunnel as described in claim 1, characterized in that: The insulated tee connector (10) is located at the bottom of the handhole (4).

7. The drainage system combining a deep-buried central drainage ditch with the main tunnel as described in claim 1, characterized in that: The vertical drainage hole (9) is drilled downward from the bottom of the hand hole (4) and extends to the central buried water ditch (6).

8. A construction method for a drainage system combining a central buried water ditch with the main tunnel as described in any one of claims 1-7, characterized in that: The construction method includes the following steps: Before or during the construction of the main tunnel, a water ditch is buried deep in the center of the construction site below the main tunnel using the pipe jacking method (6). When constructing the invert arch and filling layer of the tunnel, handholes are reserved along the longitudinal direction of the tunnel at the designed spacing (4), and a circumferential drainage blind pipe is installed at the bottom of the invert arch (3). A circumferential drainage blind pipe (1) and a longitudinal drainage blind pipe (2) of the arch wall are laid on the surface of the initial support (7) and collected through a joint; The collected drainage is directed to the bottom of the invert and connected to the tunnel bottom circumferential drainage blind pipe (3). The end of the tunnel bottom circumferential drainage blind pipe (3) is directed to the manhole (4). A vertical drain hole (9) is drilled downwards at the handhole (4) until it penetrates into the central buried water ditch (6). A vertical drainage blind pipe (5) is installed in the vertical drain hole (9). Install an insulated tee connector (10) at the bottom of the handhole (4) and connect the tunnel bottom circumferential drainage blind pipe (3) and the vertical drainage blind pipe (5) through the insulated tee connector (10) to complete the connection of the drainage system.

9. The construction method of the drainage system combining the deep-buried water ditch in the center of the tunnel with the main tunnel as described in claim 8, characterized in that: When the main tunnel is constructed using the TBM method, the invert is a precast invert block (11). The bottom of the precast invert block (11) is reserved with a circumferential drainage channel (12). The handhole (4) and the circumferential drainage channel (12) are formed and reserved together during the factory prefabrication stage of the precast invert block (11).

10. The construction method of the drainage system combining the deep-buried water ditch in the center of the tunnel with the main tunnel as described in claim 8, characterized in that: When the tunnel main tunnel is constructed using the drill-and-blast method, the invert arch is a cast-in-place invert arch (13). The handhole (4) is formed by pre-reserving a pre-set template when the cast-in-place invert arch (13) concrete and the filling layer concrete are poured.

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