A method for cleaning, separating and draining sewage at a bifurcation point in an overpass tunnel

Abstract

The present invention provides a method for separating clean and dirty water from drainage at a bifurcation of an overpass tunnel. Independent drainage ditches are provided on both sides of the main tunnel, ramp tunnel, and merge tunnel outside the driving range of the road. The drainage ditch consists of a sewage ditch and a clean water ditch. The drainage ditch that needs to be diverted and drained passes through a "manual + buried transverse connecting channel" to form an independent loop for the clean water ditch and the sewage ditch. The gravity self-flow characteristics of the drainage ditch are utilized to discharge clean water and sewage along the longitudinal slope of the tunnel, thereby realizing the classified collection and separate discharge of clean and dirty water. The drainage ditch connection method of the present invention is efficient, simple, and easy to construct. It can avoid the occurrence of small longitudinal slope sections or local low points in the drainage ditch at the bifurcation of the overpass tunnel, thereby improving drainage efficiency. The inspection wells and transverse connecting channels provided make the road surface continuous and beautiful, and there is no hidden danger of "jumping off the vehicle" during driving. The clean water ditch inspection well cover also has the function of a sewage ditch, and is easy to install or replace. The sand settling tank and the shorter transverse connecting channel are provided to facilitate maintenance and cleaning, and have little impact on driving during maintenance.

Description

Technical field:

[0001] The invention belongs to the technical field of tunnels and underground engineering, and in particular relates to a method for cleaning, separating and draining sewage at a bifurcation in an overpass tunnel. Background technology:

[0002] Drill-and-blast tunnels typically feature two independent clean water and sewage collection and drainage systems to meet environmental requirements for clean and sewage separation. To facilitate operation and maintenance, sewage ditches are typically located on both sides of the road, flush with the road surface, while clean water ditches are typically located below them. Unlike independent, through-type tunnels, the drainage system for an interchange tunnel requires comprehensive consideration of the vertical design of each tunnel within the interchange area. Under certain specific road surface transverse and longitudinal slope design conditions, the drainage ditch may have a local low point at the tunnel bifurcation point, necessitating diversion measures to ensure the integrity and smooth flow of the clean and sewage drainage system throughout the interchange tunnel and avoid the risk of tunnel flooding.

[0003] At the bifurcation of an interchange tunnel, where the separated mainline and ramp tunnels gradually merge into a converging tunnel, if there is a local low point in the drainage ditch at the bifurcation point (especially the drainage ditch on both sides of the rock in the separated tunnel, which is interrupted at the bifurcation point), the common drainage solution is:

[0004] (1) Sewage system: A cross-ditch is set up at the bifurcation of the tunnel to collect sewage in the tunnel and connect the sewage ditches on both sides of the road. According to the experience of many domestic tunnels with cross-ditch installation on the road, the cross-ditch often causes "jumping" due to differential settlement of the cover plate, and even the cover plate or the cross-ditch concrete is damaged, which poses a certain driving safety hazard.

[0005] (2) Clean water system: The clean water ditch is usually in the form of a hidden ditch. At the bifurcation, a similar "Y"-shaped diversion and merging method is used to gradually move the clean water ditches on both sides of the separated tunnel closer to the clean water ditch on the side that connects to the merged tunnel after merging. In the specific implementation process, the clean water ditches on both sides of the separated tunnel are easily affected by the transverse and longitudinal slopes of the tunnel diversion and merging area during the merging transition process, resulting in greater difficulty in the elevation positioning of the clean water ditch transition section. Large errors often occur during construction and layout, resulting in small longitudinal slope sections or local low points in the clean water ditch transition area, affecting drainage efficiency. In addition, the clean water ditch transition section has a large oblique span from the bottom of the road surface, making operation and maintenance inconvenient. Summary of the invention:

[0006] In order to solve the above-mentioned problems in the prior art, the present invention provides a clean and sewage separation drainage method at the bifurcation of an overpass tunnel. According to the superimposed influence of the transverse slope and longitudinal slope of the road surface at the bifurcation of the tunnel, the drainage ditch is drained by gravity and diversion, and the auxiliary measures of "inspection well + buried transverse connecting channel" are adopted to make the clean water ditch and sewage ditch of the overpass tunnel form independent loops, so as to achieve the purpose of utilizing the gravity self-flow characteristics of the drainage ditch to discharge clean water and sewage along the longitudinal slope of the tunnel.

[0007] In order to achieve the above object, the technical solution of the present invention is:

[0008] A method for separating and draining sewage at a bifurcation in an overpass tunnel, wherein the bifurcation in the overpass tunnel refers to the bifurcation area formed by the intersection of a mainline tunnel, a ramp tunnel, and a confluence tunnel formed by the two. The method is characterized by comprising:

[0009] 1. Independent drainage ditches shall be installed on both sides of the mainline tunnel, ramp tunnel and merge tunnel outside the driving range of the road, including the mainline tunnel transverse slope low side drainage ditch, the mainline tunnel transverse slope high side drainage ditch, the ramp tunnel transverse slope low side drainage ditch, the ramp tunnel transverse slope high side drainage ditch, the merge tunnel transverse slope low side drainage ditch, and the merge tunnel transverse slope high side drainage ditch. All of the above drainage ditches shall consist of sewage ditches flush with the road surface and clear water ditches located below the sewage ditches;

[0010] 2. The mainline tunnel, ramp tunnel, and merge tunnel at the fork of the interchange tunnel have the same longitudinal slope and are all located in the downhill section of the route; the mainline tunnel's low-side transverse slope drainage ditch and the ramp tunnel's high-side transverse slope drainage ditch are local low points at the fork of the interchange tunnel and terminate at the fork; at the same cross-sectional position, the ramp tunnel's low-side transverse slope drainage ditch is at a lower elevation than the mainline tunnel's low-side transverse slope drainage ditch and the ramp tunnel's high-side transverse slope drainage ditch;

[0011] 3. The clean and sewage separation drainage scheme includes: the high-side drainage ditch of the main line tunnel and the high-side drainage ditch of the merge tunnel are connected along the longitudinal slope of the tunnel at the bifurcation of the interchange tunnel and discharge clean water and sewage; the low-side drainage ditch of the main line tunnel and the high-side drainage ditch of the ramp tunnel are diverted and drained to the low-side drainage ditch of the ramp tunnel through inspection wells and buried horizontal connecting channels, and after being connected to the low-side drainage ditch of the merge tunnel, the clean water and sewage are discharged separately along the longitudinal slope of the tunnel.

[0012] Furthermore, the high-side transverse slope drainage ditch of the main line tunnel is connected with the high-side transverse slope drainage ditch of the merging tunnel at the bifurcation of the overpass tunnel along the longitudinal slope of the tunnel, and the low-side transverse slope drainage ditch of the ramp tunnel is connected with the low-side transverse slope drainage ditch of the merging tunnel at the bifurcation of the overpass tunnel along the longitudinal slope of the tunnel; the low-side transverse slope drainage ditch of the main line tunnel and the high-side transverse slope drainage ditch of the ramp tunnel are respectively provided with a clear water ditch inspection well and a sewage ditch inspection well near the bifurcation of the tunnel, and the low-side transverse slope drainage ditch of the ramp tunnel is provided with a clear water ditch inspection well and a sewage ditch inspection well at the connection with the low-side transverse slope drainage ditch of the merging tunnel; a transverse connecting channel located below the road surface is provided between adjacent inspection wells, including a sewage ditch transverse connecting channel connecting adjacent sewage ditch inspection wells and a clear water ditch transverse connecting channel connecting adjacent clear water ditch inspection wells, and the gravity self-flow characteristics of the drainage ditch are utilized to divert the low-side transverse slope drainage ditch of the main line tunnel and the high-side transverse slope drainage ditch of the ramp tunnel to the low-side transverse slope drainage ditch of the ramp tunnel.

[0013] Furthermore, the clear water ditch inspection well and the sewage ditch inspection well are arranged outside the driving area.

[0014] Furthermore, the sewage ditch inspection well and the clean water ditch inspection well are respectively arranged in sequence at the bifurcation of the main line tunnel low side drainage ditch, the ramp tunnel low side drainage ditch, and the ramp tunnel high side drainage ditch along the vehicle's forward direction.

[0015] Furthermore, the sewage ditch transverse connecting channel and the clean water ditch transverse connecting channel are respectively higher than the bottom elevation of the sewage ditch inspection well and the bottom elevation of the clean water ditch inspection well.

[0016] Furthermore, the slope of the transverse connecting passage is not less than 1.5% of the transverse slope of the overpass tunnel pavement. Preferably, the slope of the transverse connecting passage is consistent with the transverse slope of the overpass tunnel pavement.

[0017] Furthermore, an inspection well sedimentation tank is set at the bottom of the clear water ditch inspection well and the sewage ditch inspection well.

[0018] Furthermore, the clean water ditch is provided with a local concave section in the area below the sewage ditch inspection well to avoid the sewage ditch inspection well.

[0019] Furthermore, the bottom elevation of the local concave section of the Qingshui ditch is not lower than the bottom elevation of the Qingshui ditch inspection well.

[0020] Furthermore, the drainage ditch on the lower side of the ramp tunnel transverse slope is provided with a clean water ditch inspection well cover which also serves as a sewage ditch, so that the clean water ditch inspection well cover and the sewage ditch are built together as a whole, which is convenient for installation, maintenance and replacement.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] (1) The present invention proposes a method for separating clean and dirty water from drainage at the bifurcation of an overpass tunnel. According to the design conditions of the transverse and longitudinal slopes of the road surface at the bifurcation, the gravity flow characteristics of the clean water and sewage ditches are utilized to realize drainage diversion. The clean water ditch and the sewage ditch at the bifurcation are matched and connected and then discharged along the longitudinal slope of the tunnel, thereby ensuring that the clean and dirty water drainage system of the overpass tunnel is complete and unobstructed, realizing the classified collection and separate discharge of clean and dirty water, and embodying the concepts of "environmental protection", "low carbon" and "green".

[0023] (2) The drainage ditch connection method of the present invention is efficient, simple, easy to construct, and has a clear drainage direction. It can avoid the occurrence of small longitudinal slope sections or local low points in the drainage ditch at the branching point of the overpass tunnel, thereby improving drainage efficiency.

[0024] (3) The present invention only sets up inspection wells outside the driving area, and the transverse connecting channel is located below the road surface. No exposed structures (such as cross-cutting ditches, covers, etc.) are set up within the road surface. The road surface is continuous and beautiful, and there is no hidden danger of "jumping off the vehicle" when driving.

[0025] (4) The clean ditch inspection well cover of the present invention can also serve as a sewage ditch. It is prefabricated and easy to install or replace. A sand settling tank is set in the inspection well. The length of the horizontal connecting passage between the inspection wells is relatively short, which is convenient for maintenance and cleaning, and has little impact on traffic during maintenance. Description of the drawings:

[0026] Figure 1 This is a plan layout of the drainage scheme at the bifurcation of the interchange tunnel in a specific implementation method;

[0027] Figure 2 Schematic diagram of the longitudinal sections of each tunnel at the bifurcation of the overpass tunnel in a specific implementation method;

[0028] Figure 3 This is a cross-sectional view of the AA section of the Qingshui ditch at the bifurcation of the overpass tunnel in a specific implementation method;

[0029] Figure 4 This is a cross-sectional view BB of the transverse connection of the sewage ditch at the bifurcation of the overpass tunnel in a specific embodiment;

[0030] Figure 5 It is a CC cross-sectional view of the longitudinal connection of the drainage ditch at the bifurcation of the interchange tunnel in a specific embodiment;

[0031] Figure 6 It is a schematic diagram of the overall prefabrication of the clean ditch inspection well cover and the sewage ditch in a specific implementation method.

[0032] As shown in the figure: 1. Mainline tunnel transverse slope low side drainage ditch, 2. Mainline tunnel transverse slope high side drainage ditch, 3. Ramp tunnel transverse slope low side drainage ditch, 4. Ramp tunnel transverse slope high side drainage ditch, 5. Merging tunnel transverse slope low side drainage ditch, 6. Merging tunnel transverse slope high side drainage ditch, 7. Tunnel pavement, 8. Sewage ditch, 9. Normal section of clear water ditch, 10. Clear water ditch cover, 11. Clear water ditch inspection well, 12. Clear water ditch transverse connecting passage, 13. Sewage ditch inspection well, 14. Sewage ditch transverse connecting passage, 15. Partially concave section of clear water ditch, 16. Clear water ditch inspection well cover, 17. Sewage ditch inspection well cover, 18. Inspection well sand settling tank, 19. Clear water ditch inspection well cover also serving as sewage ditch, 20. Concrete around the ditch body, 21. Inner contour of mainline tunnel, 22. Inner contour of ramp tunnel, 23. Inner contour of merge tunnel, 24. Building limit, 25. Cable trench. Specific implementation method:

[0033] The following, with reference to the accompanying drawings, uses an overpass tunnel as an example to clearly and completely describe the technical solution of the present invention. Obviously, the embodiments described are only a portion of the embodiments of the present invention, not all of them. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort are intended to fall within the scope of protection of the present invention.

[0034] In this overpass tunnel example, a method for separating and draining clean and dirty water at an overpass tunnel bifurcation is provided. The overpass tunnel bifurcation refers to the bifurcation area formed by the intersection of the main line tunnel, the ramp tunnel, and the confluence tunnel after the two merge.

[0035] Independent drainage ditches are set up on both sides of the main line tunnel, ramp tunnel and merge tunnel outside the driving range of the road. The drainage ditches include sewage ditches and clear water ditches. The sewage ditches are flush with the road surface and collect the sewage flushing in the tunnel. The clear water ditches are located below the sewage ditches and collect the surrounding rock water outside the tunnel secondary lining structure. For details, see Figure 1 As shown, a main line tunnel high-slope drainage ditch 2 (including clean water and sewage ditch) is set on the high side of the main line tunnel transverse slope, a main line tunnel low-slope drainage ditch 1 (including clean water and sewage ditch) is set on the low side of the main line tunnel transverse slope, a ramp tunnel high-slope drainage ditch 4 (including clean water and sewage ditch) is set on the high side of the ramp tunnel transverse slope, a ramp tunnel low-slope drainage ditch 3 (including clean water and sewage ditch) is set on the low side of the ramp tunnel transverse slope, a merging tunnel high-slope drainage ditch 6 (including clean water and sewage ditch) is set on the high side of the merging tunnel transverse slope, and a merging tunnel low-slope drainage ditch 5 (including clean water and sewage ditch) is set on the low side of the merging tunnel transverse slope.

[0036] The main line tunnel, ramp tunnel and merge tunnel at the tunnel bifurcation have the same longitudinal slope direction and are all located in the downhill section of the route. For the longitudinal section diagram of each tunnel, please refer to Figure 2 As shown, the transverse slope at the bifurcation is oriented to the right of the vehicle's forward direction, and no superelevation is provided. The mainline tunnel transverse slope high side drainage ditch 2 (including clean water and sewage ditch) and the merging tunnel transverse slope high side drainage ditch 6 (including clean water and sewage ditch) are connected along the tunnel longitudinal slope at the bifurcation. The ramp tunnel transverse slope low side drainage ditch 3 (including clean water and sewage ditch) and the merging tunnel transverse slope low side drainage ditch 5 (including clean water and sewage ditch) are connected along the tunnel longitudinal slope at the bifurcation. According to the above tunnel longitudinal slope conditions, the mainline tunnel transverse slope high side drainage ditch 2 (including clean water and sewage ditch) can flow into and along the merging tunnel transverse slope high side drainage ditch 6 (including clean water and sewage ditch), and the ramp tunnel transverse slope low side drainage ditch 3 (including clean water and sewage ditch) can also flow into and along the merging tunnel transverse slope low side drainage ditch 5 (including clean water and sewage ditch).

[0037] The mainline tunnel's transverse slope low-side drainage ditch 1 (including clear water and sewage ditch) and the ramp tunnel's transverse slope high-side drainage ditch 4 (including clear water and sewage ditch) are at a local low point at the tunnel bifurcation and terminate at the bifurcation, with no drainage outlet. Diversion and drainage are required to ensure the smooth flow of the interchange tunnel's drainage system. The transverse slope of the interchange tunnel pavement is set so that the elevation of the ramp tunnel's transverse slope low-side drainage ditch 3 is lower than that of the mainline tunnel's transverse slope low-side drainage ditch 1 and the ramp tunnel's transverse slope high-side drainage ditch 4 at the same cross-sectional location. The gravity flow characteristics of the ditch can be utilized to divert water from the mainline tunnel's transverse slope low-side drainage ditch 1 (including clear water and sewage ditch) and the ramp tunnel's transverse slope high-side drainage ditch 4 (including clear water and sewage ditch) to the ramp tunnel's transverse slope low-side drainage ditch 3 (including clear water and sewage ditch).

[0038] Specifically, the overall drainage organization flow direction of the tunnel bifurcation area in this embodiment is: 1) the main line tunnel transverse slope high side drainage ditch 2 (including clean water and sewage ditch) → the confluence tunnel transverse slope high side drainage ditch 6 (including clean water and sewage ditch); 2) the main line tunnel transverse slope low side drainage ditch 1 (including clean water and sewage ditch) → the ramp tunnel transverse slope high side drainage ditch 4 (including clean water and sewage ditch) → the ramp tunnel transverse slope low side drainage ditch 3 (including clean water and sewage ditch) → the confluence tunnel transverse slope low side drainage ditch 5 (including clean water and sewage ditch). The drainage plan can be found in Figure 1 .

[0039] For the mainline tunnel low-slope drainage ditch 1 and ramp tunnel high-slope drainage ditch 4, both of which are to be diverted and drained, clean water ditch inspection wells and sewage ditch inspection wells are installed near the tunnel bifurcations. Transverse connecting passages located below the road surface are provided between the inspection wells. Specifically, sewage ditch inspection wells 13 and clean water ditch inspection wells 11 are provided in sequence along the vehicle's forward direction in the tunnel bifurcations. Adjacent clean water ditch inspection wells 11 are connected by a clean water ditch transverse connecting passage 12, and adjacent sewage ditch inspection wells 13 are connected by a sewage ditch transverse connecting passage 14. Leveraging the gravity-driven flow characteristics of the drainage ditch, the mainline tunnel low-slope drainage ditch 1 and the ramp tunnel high-slope drainage ditch 4 are diverted and drained through the transverse connecting passages to the ramp tunnel low-slope drainage ditch 3, ultimately connecting to the merge tunnel low-slope drainage ditch 5. Clean water and sewage are discharged separately along the longitudinal slope of the tunnel.

[0040] The sewage ditch inspection well 13 is set in the lateral width space outside the driving area. The sewage ditch transverse connecting channel 14 is located below the road surface and connects the adjacent sewage ditch inspection wells. The transverse connection cross-section structure is shown in FIG. Figure 4 .

[0041] The Qingshuigou inspection well 11 is set in the lateral width space outside the driving area. The Qingshuigou transverse connecting channel 12 is located under the road surface and connects the adjacent Qingshuigou inspection wells. The transverse connecting cross-section structure is shown in FIG. Figure 3 .

[0042] The horizontal connecting channel 12 of the clean water ditch and the horizontal connecting channel 14 of the sewage ditch are preferably pre-buried pipes with a certain strength, and their horizontal slope is not less than 1.5, preferably consistent with the horizontal slope of the road.

[0043] See also Figures 5 and 6 The sewage ditch transverse connecting channel 14 and the clean water ditch transverse connecting channel 12 are respectively higher than the bottom elevation of the sewage ditch inspection well 13 and the clean water ditch inspection well 11, preferably 100mm, to facilitate operation and maintenance. An inspection well grit chamber 18 is set at the bottom of the clean water ditch inspection well 11 and the sewage ditch inspection well 13.

[0044] A local concave section of the Qingshui ditch is set in the area below the sewage ditch inspection well to avoid the sewage ditch inspection well. The bottom elevation of the local concave section of the Qingshui ditch is not lower than the bottom elevation of the Qingshui ditch inspection well. Specifically, taking the location of the low-side drainage ditch 1 on the transverse slope of the main tunnel as an example, near the sewage ditch inspection well 13, the low-side drainage ditch 1 on the transverse slope of the main tunnel of the Qingshui ditch is changed from the normal section 9 of the Qingshui ditch to the local concave section 15 of the Qingshui ditch located below the sewage ditch inspection well 13. The bottom elevation of the local concave section 15 of the Qingshui ditch is not lower than the bottom elevation of the Qingshui ditch inspection well 11. Its longitudinal connection profile structure is shown in FIG. Figure 5 .

[0045] The sewage ditch located at the low-side drainage ditch 1 of the main line tunnel and the high-side drainage ditch 4 of the ramp tunnel can terminate at the sewage ditch inspection well 13, that is, no sewage ditch can be set between the clear water ditch inspection well 11 and the sewage ditch inspection well 13.

[0046] The sewage ditch of the ramp tunnel transverse slope low side drainage ditch 3 needs to be connected with the combined tunnel transverse slope low side drainage ditch 5, that is, the clear water ditch inspection well cover needs to reserve sewage crossing conditions. It can be considered to set up a clear water ditch inspection well cover 19 that also serves as a sewage ditch. The clear water ditch inspection well cover and the sewage ditch are built together as a whole and serve as a sewage ditch to facilitate maintenance and replacement. The method is referred to Figure 6 .

[0047] The above is a method for separating clean and dirty water from the bifurcation of a tunnel based on the example of the overpass tunnel, determined according to the transverse and longitudinal slope conditions at the bifurcation of the tunnel. For overpass tunnels with other transverse and longitudinal slope conditions, the drainage scheme can also be designed according to similar design ideas. The overall idea of ​​determining the drainage scheme is to divert and drain the drainage ditches that do not have gravity flow conditions, so that the clean and dirty water ditches of the overpass tunnel form a complete system. Under certain special conditions, if the longitudinal slope low point cannot be avoided after diversion by the above method, resulting in the inability of the ditch to drain water by itself, it is still necessary to consider adopting other drainage measures within the scope of existing technologies, including reverse slope drainage, setting up pump houses, and drainage cross tunnels.

[0048] The above is a description of the basic principles and main features of the present invention. Although the description is relatively specific and detailed, it should not be construed as limiting the scope of the present invention. It should be noted that various modifications and improvements may be made without departing from the spirit of the present invention, and all such modifications and improvements fall within the scope of protection of the present invention, which is defined by the appended claims and their equivalents.

Claims

1. A method for separating and draining sewage at a bifurcation in an overpass tunnel, wherein the bifurcation in the overpass tunnel refers to the bifurcation area formed by the intersection of the main line tunnel, the ramp tunnel, and the confluence tunnel after the two merge; characterized in that: include: 1) Independent drainage ditches are set up on both sides of the main line tunnel, ramp tunnel and merge tunnel outside the driving range of the road, including the main line tunnel transverse slope low side drainage ditch (1), the main line tunnel transverse slope high side drainage ditch (2), the ramp tunnel transverse slope low side drainage ditch (3), the ramp tunnel transverse slope high side drainage ditch (4), the merge tunnel transverse slope low side drainage ditch (5), and the merge tunnel transverse slope high side drainage ditch (6). The above drainage ditches are composed of sewage ditches flush with the road surface and clear water ditches located below the sewage ditches; 2) The longitudinal slopes of the main line tunnel, ramp tunnel and merge tunnel at the fork of the interchange tunnel are consistent and are all located in the downhill section of the route; the main line tunnel transverse slope low side drainage ditch (1) and the ramp tunnel transverse slope high side drainage ditch (4) are local low points at the fork of the interchange tunnel and terminate at the fork; at the same cross-sectional position, the elevation of the ramp tunnel transverse slope low side drainage ditch (3) is lower than that of the main line tunnel transverse slope low side drainage ditch (1) and the ramp tunnel transverse slope high side drainage ditch (4); 3) Clean and sewage separation drainage includes: the main line tunnel transverse slope high side drainage ditch (2) and the merge tunnel transverse slope high side drainage ditch (6) are connected along the tunnel longitudinal slope at the interchange tunnel bifurcation and discharge clean water and sewage; the main line tunnel transverse slope low side drainage ditch (1) and the ramp tunnel transverse slope high side drainage ditch (4) are diverted and drained to the ramp tunnel transverse slope low side drainage ditch (3) through the inspection well and the buried transverse connecting channel, and then connected to the merge tunnel transverse slope low side drainage ditch (5), and the clean water and sewage are discharged along the longitudinal slope of the tunnel respectively; The main line tunnel transverse slope high side drainage ditch (2) and the merge tunnel transverse slope high side drainage ditch (6) are connected along the tunnel longitudinal slope at the bifurcation of the overpass tunnel, and the ramp tunnel transverse slope low side drainage ditch (3) and the merge tunnel transverse slope low side drainage ditch (5) are connected along the tunnel longitudinal slope at the bifurcation of the overpass tunnel; the main line tunnel transverse slope low side drainage ditch (1) and the ramp tunnel transverse slope high side drainage ditch (4) A clear water ditch inspection well (11) and a sewage ditch inspection well (13) are respectively arranged near the bifurcation of the tunnel; a clear water ditch inspection well (11) and a sewage ditch inspection well (13) are arranged at the junction of the ramp tunnel transverse slope low side drainage ditch (3) and the confluence tunnel transverse slope low side drainage ditch (5); a transverse connecting channel located below the road surface is arranged between adjacent inspection wells, including a sewage ditch transverse connecting channel (14) connecting adjacent sewage ditch inspection wells (13) and a clear water ditch transverse connecting channel (12) connecting adjacent clear water ditch inspection wells (11); and the main line tunnel transverse slope low side drainage ditch (1) and the ramp tunnel transverse slope high side drainage ditch (4) are diverted and drained to the ramp tunnel transverse slope low side drainage ditch (3) by utilizing the gravity self-flow characteristics of the drainage ditch.

2. The method for cleaning, separating and draining sewage at a bifurcation of an overpass tunnel according to claim 1, characterized in that: The clean water ditch inspection well (11) and the sewage ditch inspection well (13) are arranged outside the driving area.

3. The method for cleaning, separating and draining sewage at a bifurcation of an overpass tunnel according to claim 2, characterized in that: The sewage ditch inspection well (13) and the clean water ditch inspection well (11) are respectively arranged in sequence at the tunnel bifurcations of the main line tunnel transverse slope low side drainage ditch (1), the ramp tunnel transverse slope low side drainage ditch (3), and the ramp tunnel transverse slope high side drainage ditch (4) along the vehicle forward direction.

4. The method for cleaning, separating and draining sewage at a bifurcation of an overpass tunnel according to claim 1, characterized in that: The sewage ditch transverse connecting channel (14) and the clean water ditch transverse connecting channel (12) are respectively higher than the bottom elevation of the sewage ditch inspection well (13) and the bottom elevation of the clean water ditch inspection well (11).

5. The method for cleaning, separating and draining sewage at a bifurcation of an overpass tunnel according to claim 1, characterized in that: The slope of the transverse connecting channel and the transverse slope of the interchange tunnel pavement shall not be less than 1.5%.

6. The method for cleaning, separating and draining sewage at a bifurcation of an overpass tunnel according to claim 5, characterized in that: The slope of the transverse connecting channel is consistent with the transverse slope of the overpass tunnel road surface.

7. The method for cleaning, separating and draining sewage at a bifurcation of an overpass tunnel according to claim 1, characterized in that: An inspection well sedimentation tank (18) is provided at the bottom of the clean water ditch inspection well (11) and the sewage ditch inspection well (13).

8. The method for cleaning, separating and draining sewage at a bifurcation point in an overpass tunnel according to claim 1, characterized in that: The clear water ditch is provided with a local concave section (15) of the clear water ditch in an area below the sewage ditch inspection well (13).

9. The method for cleaning, separating and draining sewage at a bifurcation of an overpass tunnel according to claim 8, characterized in that: The bottom elevation of the local concave section (15) of the clear water ditch is not lower than the bottom elevation of the clear water ditch inspection well (11).

10. The method for cleaning, separating and draining sewage at a bifurcation of an overpass tunnel according to claim 1, characterized in that: The drainage ditch (3) on the lower side of the ramp tunnel transverse slope is provided with a clear water ditch inspection well cover (19) which also serves as a sewage ditch.

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