A combined central drainage system for expanding tunnel drainage capacity

Abstract

This utility model discloses a combined central drainage system for expanding the drainage capacity of tunnels, belonging to the technical field of tunnel drainage systems. The tunnel contains a road structure, within which an existing central ditch and a newly constructed drainage ditch are arranged longitudinally along the tunnel. The newly constructed drainage ditch connects to the existing central ditch via several drainage components. This combination of components and the newly constructed drainage ditch forms a combined central drainage system with enhanced overall drainage capacity, effectively reducing the scale of project scrapping and improving economic efficiency. Furthermore, during construction, only one side of the existing central ditch needs to be excavated, preserving the existing central ditch and effectively ensuring the tunnel's drainage needs during construction. Since the excavation site is located on one side of the existing central ditch, half of the tunnel remains open to traffic, facilitating traffic organization during construction.

Description

Technical Field

[0001] This utility model relates to a combined central drainage system for expanding the drainage capacity of tunnels, belonging to the field of tunnel drainage technology. Background Technology

[0002] As tunnels have been in operation for longer periods, a series of problems, such as road seepage and water inrush, have gradually emerged. The main reason for these problems is the blockage of the existing tunnel drainage system, leading to poor drainage of groundwater around the tunnel. Furthermore, the drainage systems of early tunnels also suffer from insufficient design capacity, especially the early circular central drainage ditches. These ditches have relatively small overall diameters and limited drainage capacity, making them unable to effectively cope with the problem of water inrush during concentrated rainfall in the rainy season. This is a significant cause of water leakage in the tunnel lining and water inrush on the road surface during the rainy season. To address the insufficient drainage capacity of existing tunnel central ditches, the general construction method is to excavate the existing circular central ditches and then rebuild rectangular central ditches in their original locations.

[0003] While the aforementioned solutions can effectively improve the drainage capacity of the tunnel's central ditch, they present challenges such as difficulties in tunnel drainage during construction, the need for complete closure of tunnel traffic during construction, and the economic loss associated with the complete scrapping of the existing circular drainage ditch. Therefore, researching a combined central drainage system for expanding tunnel drainage capacity is of significant practical importance. Utility Model Content

[0004] To solve the above-mentioned technical problems, this utility model provides a combined central drainage system for expanding the drainage capacity of tunnels.

[0005] This utility model is achieved through the following technical solution:

[0006] A combined central drainage system for expanding the drainage capacity of a tunnel, wherein a road structure is provided inside the tunnel, and an existing central ditch and a newly built drainage ditch are provided along the longitudinal direction of the tunnel within the road structure, and the newly built drainage ditch is connected to the existing central ditch through several drainage components.

[0007] The road structure has multiple transverse drainage pipes on both sides of the drainage component. One end of the transverse drainage pipe is connected to the tunnel circumferential drainage pipe and the tunnel longitudinal drainage pipe, and the other end is connected to the existing tunnel central ditch or a newly built drainage ditch.

[0008] The road structure includes, from bottom to top, an inverted arch backfill layer, a concrete pavement slab, and an asphalt surface layer.

[0009] The existing tunnel central trench includes a central trench and a circular pipe trench. The central trench is located within the backfill layer of the invert arch, and the circular pipe trench is located within the central trench. Geotextile-wrapped gravel is laid on the upper side of the circular pipe trench in the central trench to form a blind ditch at the top of the trench. Multiple drainage holes are opened on the side of the circular pipe trench facing the blind ditch at the top of the trench.

[0010] The circular pipe trench includes multiple circular pipe segments, and adjacent circular pipe segments are connected through a central trench inspection well.

[0011] The top of the central ditch inspection well is equipped with an anti-buoyancy and seepage-proof cover plate, which is located inside the concrete pavement slab, and the top surface of the anti-buoyancy and seepage-proof cover plate is coplanar with the top surface of the concrete pavement slab.

[0012] The anti-buoyancy and seepage-proof cover plate includes a reinforced concrete cover plate body and a water-swellable waterstop strip. The water-swellable waterstop strip is evenly wrapped around and adhered to the side wall of the reinforced concrete cover plate body.

[0013] The newly constructed drainage ditch is a rectangular drainage ditch, located on the side of the road structure with a higher cross slope. It includes a drainage ditch channel and a water ditch body located within the drainage ditch channel. Concrete backfill ditch sides are provided between the water ditch body and the two side walls of the drainage ditch channel. A precast reinforced concrete cover plate is provided on the top of the water ditch body, and the precast reinforced concrete cover plate is located on the underside of the concrete road slab.

[0014] The ditch body is divided into multiple sections, and adjacent sections of the ditch body are connected by ditch inspection wells. The ditch inspection wells are aligned with the central ditch inspection wells in the transverse direction of the tunnel. A special-shaped concrete backfill ditch side is provided between the ditch inspection wells and the central ditch inspection wells. Several water guide pipes B connecting the upper part of the ditch inspection wells and the upper part of the central ditch inspection wells are provided in the special-shaped concrete backfill ditch side.

[0015] The diameter of the water pipe B is 160mm to 200mm. The spacing between several water pipes B is 0.5m. The distance from the water pipe B to the concrete pavement is 30cm. The water pipe B has a downward slope of not less than 2% from the side of the central ditch inspection well to the side of the water ditch inspection well.

[0016] The top of the inspection well in the ditch is equipped with a thickened precast reinforced concrete cover plate, which is located inside the concrete pavement slab, and the top surface of the thickened precast reinforced concrete cover plate is coplanar with the top surface of the concrete pavement slab.

[0017] The drainage assembly includes a transverse drainage ditch and multiple drainage pipes A. The transverse drainage ditch is located longitudinally along the tunnel in the concrete backfill ditch between the ditch body and the existing tunnel center ditch, and the length of the transverse drainage ditch is the same as the length of the ditch body. The transverse drainage ditch is filled with gravel wrapped with geotextile. One end of the transverse drainage ditch is connected to the top drainage ditch along the tunnel, and the other end extends to the outer wall of the ditch body. One end of the multiple drainage pipes A extends into the ditch body, and the other end extends into the transverse drainage ditch.

[0018] The geotextile in the transverse drainage blind ditch is overlapped and connected with the geotextile in the top blind ditch, and the width of the gravel filling in the transverse drainage blind ditch in the transverse direction of the tunnel, which replaces the original gravel space in the top blind ditch, is not less than 30cm.

[0019] The transverse drainage blind ditch has a downward slope of no less than 2% from the side of the existing tunnel center ditch to the side of the ditch body. The multiple drainage pipes A are set at intervals of 2m to 5m in the longitudinal direction of the tunnel, and the diameter of the drainage pipes A is 50mm to 110mm. The length of the drainage pipes A extending into the transverse drainage blind ditch is 5cm to 10cm, and multiple drainage holes are opened on the side wall of the drainage pipes A located in the transverse drainage blind ditch.

[0020] The irregular concrete backfill trench blocks the transverse water-guiding blind ditches on both sides of the water ditch inspection well, and a T-shaped connecting steel pipe is provided in the irregular concrete backfill trench. The inlet of the T-shaped connecting steel pipe extends into the transverse water-guiding blind ditch on the upstream side of the water ditch inspection well, one outlet extends into the transverse water-guiding blind ditch on the downstream side of the water ditch inspection well, and the other outlet extends into the water ditch inspection well.

[0021] Multiple drainage holes are provided on the side wall of the T-shaped connecting steel pipe extending into the transverse drainage blind ditch, and the T-shaped connecting steel pipe is wrapped with geotextile.

[0022] Corrosion-resistant steel ropes are installed inside the circular pipe section and each section of the ditch.

[0023] The two ends of the corrosion-resistant steel rope installed inside the circular pipe section are respectively tied to the external steel components on the side walls of the central trench inspection wells at both ends of the circular pipe section, and the middle part of the corrosion-resistant steel rope is located in the upper half of the inner cavity of the circular pipe section.

[0024] The two ends of the corrosion-resistant steel rope installed inside the ditch are tied to the external steel components on the side walls of the inspection wells at both ends of the ditch section, and the middle part of the corrosion-resistant steel rope is located in the upper half of the inner cavity of the ditch.

[0025] The beneficial effects of this utility model are as follows: the newly built drainage channel connects to the existing tunnel central ditch through multiple drainage components, thereby forming a combined central drainage system. Compared with the conventional method of demolishing and rebuilding the existing tunnel central ditch, it has a stronger comprehensive drainage capacity, effectively reduces the scale of project scrapping, and is more economical. In addition, during construction, only the road structure on one side of the existing tunnel central ditch needs to be excavated, and the existing tunnel central ditch is preserved, which can effectively ensure the drainage needs of the tunnel during construction. Moreover, since the construction excavation site is located on one side of the existing tunnel central ditch, half of the tunnel is open to traffic, which is beneficial to traffic organization during construction. Attached Figure Description

[0026] Figure 1 This is a schematic cross-sectional view of the present invention at the body of the ditch;

[0027] Figure 2 This is a schematic diagram of the assembly structure of the road structure, the central ditch of the existing tunnel, the newly built drainage ditch, the drainage components, the transverse drainage pipe and the tie rod, etc. of this utility model;

[0028] Figure 3 This is a schematic cross-sectional view of the present invention at the inspection well in the ditch;

[0029] Figure 4 This is a schematic diagram of the assembly structure of the road structure, central ditch inspection well, water ditch inspection well, water guide pipe B, T-shaped connecting steel pipe, etc. of this utility model;

[0030] Figure 5 This is a schematic diagram of the anti-buoyancy and seepage-proof cover plate of this utility model;

[0031] Figure 6 This is a top view of the existing tunnel central ditch, the newly built drainage ditch, and the drainage components after the completion of construction according to this utility model.

[0032] Figure 7 This is a partial top view of the existing tunnel central ditch, the newly built drainage ditch, and the drainage component inspection well after the completion of the construction of the drainage ditch according to this utility model;

[0033] Figure 8 This is a schematic diagram of the assembly structure of the irregular concrete backfill trench, the transverse drainage blind ditch, and the T-shaped connecting steel pipe of this utility model.

[0034] In the diagram: 1-Tunnel, 2-Road structure, 21-Backfill layer of invert arch, 22-Concrete pavement slab, 23-Asphalt surface layer, 3-Central ditch of existing tunnel, 31-Central ditch trench, 32-Circular pipe trench, 33-Blind ditch top, 34-Concrete foundation, 35-Inspection well of central ditch, 36-Anti-buoyancy and seepage-proof cover plate, 361-Reinforced concrete cover plate body, 362-Water-swellable waterstop strip, 4-New drainage ditch, 41-Drainage ditch trench, 42-Ditch body, 43-Inspection well of ditch, 44-Concrete backfill trench side, 45-Precast reinforced concrete cover plate, 46-Thickened precast reinforced concrete cover plate, 47-Irregularly shaped concrete backfill trench side, 5-Drainage components, 51-Transverse water-conducting blind ditch, 52-Water-conducting pipe A, 6-Water-conducting pipe B, 7-T-shaped connecting steel pipe, 8-Transverse drainage pipe, 9-Longitudinal contraction joint tie rod, 10-Corrosion-resistant steel rope. Detailed Implementation

[0035] The technical solution of this utility model is further described below, but the scope of protection is not limited to what is described.

[0036] like Figures 1 to 8 As shown, this utility model discloses a combined central drainage system for expanding the drainage capacity of tunnels. The tunnel 1 contains a road structure 2, within which an existing central tunnel ditch 3 and a newly constructed drainage ditch 4 are arranged longitudinally along the tunnel 1. The newly constructed drainage ditch 4 is connected to the existing central tunnel ditch 3 via several drainage components 5. The newly constructed drainage ditch 4, connected to the existing central tunnel ditch 3 through multiple drainage components 5, forms a combined central drainage system. Compared to the conventional method of demolishing and rebuilding the existing central tunnel ditch 3, this system offers stronger overall drainage capacity, effectively reduces the scale of project scrapping, and is more economical. Furthermore, during construction, only one side of the road structure 2 of the existing central tunnel ditch 3 needs to be excavated, allowing the existing central tunnel ditch 3 to be preserved. This effectively ensures the drainage needs of the tunnel 1 during construction. Since the excavation site is located on one side of the existing central tunnel ditch 3, half of the tunnel 1 is open to traffic, which is beneficial for traffic organization during construction.

[0037] Multiple transverse drainage pipes 8 are respectively provided on both sides of the drainage component 5 in the road structure 2. One end of the transverse drainage pipe 8 is connected to the tunnel circumferential drainage pipe and the tunnel longitudinal drainage pipe, and the other end is connected to the existing tunnel central ditch 3 or the newly built drainage ditch 4.

[0038] The road structure 2 includes, from bottom to top, an inverted arch backfill layer 21, a concrete pavement slab 22, and an asphalt surface layer 23. The function of the transverse drainage pipe 8 is to divert the groundwater behind the tunnel lining 1 to the existing tunnel central ditch 3 or the newly built drainage ditch 4.

[0039] The existing tunnel central trench 3 includes a central trench 31 and a circular pipe trench 32. The central trench 31 is located within the backfill layer 21 of the invert arch, and the circular pipe trench 32 is located within the central trench 31. Geotextile-wrapped gravel is laid on the upper side of the circular pipe trench 32 within the central trench 31 to form a blind drain 33 at the top of the trench. Multiple drainage holes are provided on the side of the circular pipe trench 32 facing the blind drain 33 at the top. The wall of the circular pipe trench 32 is a reinforced concrete structure.

[0040] The circular pipe trench 32 includes multiple circular pipe segments, and two adjacent circular pipe segments are connected through a central trench inspection well 35.

[0041] The top of the central ditch inspection well 35 is provided with an anti-buoyancy and seepage-proof cover plate 36. The anti-buoyancy and seepage-proof cover plate 36 is located inside the concrete pavement slab 22, and the top surface of the anti-buoyancy and seepage-proof cover plate 36 is coplanar with the top surface of the concrete pavement slab 22.

[0042] The anti-buoyancy and seepage-proof cover plate 36 includes a reinforced concrete cover plate body 361 and a water-swellable waterstop strip 362. The water-swellable waterstop strip 362 is evenly wrapped around and adhered to the side wall of the reinforced concrete cover plate body 361. The anti-buoyancy and seepage-proof cover plate 36 is located inside the concrete pavement slab 22. When it is necessary to inspect and repair the existing tunnel central ditch 3, the asphalt surface layer 23 can be removed to open the anti-buoyancy and seepage-proof cover plate 36.

[0043] The prerequisite for the combined drainage of the existing tunnel central ditch 3 and the newly built drainage ditch is that the existing tunnel central ditch 3 is blocked or has insufficient drainage capacity, resulting in a rise in water level. Specifically, the circular pipe section, being deeply buried below the concrete pavement slab 22 and drained through the transverse drainage blind ditch 51, has a low risk of water accumulation and bulging on the road surface above it. However, the cover plate of the central ditch inspection well 35 is directly set at the bottom of the asphalt pavement; if the water level rises, it may cause water seepage onto the pavement and the cover plate to float, leading to pavement bulging.

[0044] To address the issues of upward water seepage and cover plate bulging in the central ditch inspection well 35 under conditions of rapid water level rise, an anti-buoyancy and seepage-proof cover plate 36 was designed, with the following advantages:

[0045] When the water level in the central ditch inspection well 35 does not rise to the elevation of the anti-buoyancy and seepage prevention cover 36, the water-swellable sealing strip 362 is in normal condition. At this time, there is a small gap between the anti-buoyancy and seepage prevention cover 36 and the edge of the wellhead of the central ditch inspection well 35. During operation and maintenance, the anti-buoyancy and seepage prevention cover 36 can be opened relatively easily.

[0046] When the water level rises to the elevation of the anti-buoyancy and seepage prevention cover plate 36, the water-swellable sealing strip 362 expands upon contact with water. At this time, the anti-buoyancy and seepage prevention cover plate 36 is tightly fitted with the wellhead of the central ditch inspection well 35. On the one hand, it can prevent water from seeping back onto the road surface. On the other hand, by increasing the frictional resistance between the anti-buoyancy and seepage prevention cover plate 36 and the wellhead of the central ditch inspection well 35, the risk of the anti-buoyancy and seepage prevention cover plate 36 floating under water pressure is significantly reduced.

[0047] The newly constructed drainage ditch 4 is a rectangular drainage ditch, located on the side of the road structure 2 with a higher cross slope. It includes a drainage ditch channel 41 and a ditch body 42 within the drainage ditch channel 41. Concrete backfill ditch sides 44 are provided between the ditch body 42 and the two side walls of the drainage ditch channel 41. A precast reinforced concrete cover 45 is provided on the top of the ditch body 42, and the precast reinforced concrete cover 45 is located under the concrete pavement slab 22. Constructing the new drainage ditch 4 on the side of the road structure 2 with a higher cross slope results in a larger distance between the bottom of the tunnel 1 and the top surface of the road structure 2, ensuring sufficient space for the new drainage ditch 4. Furthermore, while ensuring that the excavation of the new drainage ditch 4 does not affect the structural stability of the existing tunnel central ditch 3, the lateral distance between the new drainage ditch 4 and the existing tunnel central ditch 3 should be minimized as much as possible, thereby reducing the width of the drainage components 5.

[0048] The ditch body 42 is provided in multiple sections, and two adjacent sections of the ditch body 42 are connected by a ditch inspection well 43. The ditch inspection well 43 is aligned with the central ditch inspection well 35 in the transverse direction of the tunnel 1. A special-shaped concrete backfill ditch side 47 is provided between the ditch inspection well 43 and the central ditch inspection well 35. Several water guide pipes B6 connecting the upper part of the ditch inspection well 43 and the upper part of the central ditch inspection well 35 are provided in the special-shaped concrete backfill ditch side 47.

[0049] The diameter of the water pipe B6 is 160mm to 200mm. The spacing between several water pipes B6 is 0.5m. The distance from the water pipe B6 to the concrete pavement slab 22 is 30cm. The water pipe B6 has a downward slope of not less than 2% from the side of the central ditch inspection well 35 to the side of the water ditch inspection well 43.

[0050] The top of the drainage ditch inspection well 43 is provided with a thickened precast reinforced concrete cover plate 46. The thickened precast reinforced concrete cover plate 46 is located inside the concrete pavement slab 22, and the top surface of the thickened precast reinforced concrete cover plate 46 is coplanar with the top surface of the concrete pavement slab 22.

[0051] The precast reinforced concrete cover plate 45 is located on the underside of the concrete pavement slab 22. If it needs to be opened later, the asphalt surface layer 23 and the concrete pavement slab 22 need to be removed. Under normal circumstances, it will not be opened because the concrete pavement slab 22 on top bears the vehicle load, so there is no need to thicken it. The thickened precast reinforced concrete cover plate 46 is located on the inside side of the concrete pavement slab 22. It can be opened by removing only the asphalt surface layer 23. It needs to replace the concrete pavement slab 22 in bearing the vehicle load, so it needs to be thickened.

[0052] The drainage component 5 includes a transverse drainage blind ditch 51 and multiple drainage pipes A52. The transverse drainage blind ditch 51 is located longitudinally along the tunnel 1 in the concrete backfill ditch sidewall 44 between the ditch body 42 and the existing tunnel central ditch 3, and the length of the transverse drainage blind ditch 51 is the same as the length of the ditch body 42. The transverse drainage blind ditch 51 is filled with gravel wrapped with geotextile. One end of the transverse drainage blind ditch 51 is connected to the top blind ditch 33 along the transverse direction of the tunnel 1, and the other end extends to the outer wall of the ditch body 42. One end of the multiple drainage pipes A52 extends into the ditch body 42, and the other end extends into the transverse drainage blind ditch 51.

[0053] The geotextile in the transverse drainage blind ditch 51 is overlapped and connected with the geotextile in the top blind ditch 33, and the width of the gravel filling in the transverse drainage blind ditch 51 in the transverse direction of tunnel 1 and replacing the original gravel space in the top blind ditch 33 is not less than 30cm.

[0054] The transverse drainage ditch 51 has a downward slope of no less than 2% from the side of the existing tunnel center ditch 3 towards the side of the ditch body 42. Multiple water pipes A52 are spaced 2m to 5m apart along the longitudinal direction of tunnel 1, and the diameter of each water pipe A52 is 50mm to 110mm. The length of each water pipe A52 extending into the transverse drainage ditch 51 is 5cm to 10cm, and multiple drainage holes are provided on the sidewall of each water pipe A52 within the transverse drainage ditch 51. The transverse drainage ditch 51 has a downward slope of no less than 2% from the side of the existing tunnel center ditch 3 towards the side of the ditch body 42 to facilitate the flow of water from the transverse drainage ditch 51 to the newly constructed drainage ditch 4.

[0055] The irregular concrete backfill trench 47 blocks the transverse water-guiding blind trenches 51 on both sides of the water ditch inspection well 43, and the irregular concrete backfill trench 47 is provided with a T-shaped connecting steel pipe 7. The inlet of the T-shaped connecting steel pipe 7 extends into the transverse water-guiding blind trench 51 on the upstream side of the water ditch inspection well 43, one of the outlets extends into the transverse water-guiding blind trench 51 on the downstream side of the water ditch inspection well 43, and the other outlet extends into the water ditch inspection well 43.

[0056] Multiple drainage holes are provided on the side wall of the T-shaped connecting steel pipe 7 extending into the transverse drainage blind ditch 51, and the T-shaped connecting steel pipe 7 is wrapped with geotextile.

[0057] Because the irregular concrete backfill ditch 47 blocks the transverse drainage blind ditch 51 on both sides of the inspection well 43, in order to ensure the smooth drainage of the transverse drainage blind ditch 51 and avoid local water accumulation, a T-shaped connecting steel pipe 7 is installed inside the T-shaped connecting steel pipe 7. The bottom elevation of the T-shaped connecting steel pipe 7 is matched with the bottom elevation of the transverse drainage blind ditch 51. The T-shaped connecting steel pipe 7 can ensure that each section of the transverse drainage blind ditch 51 is interconnected and can directly divert the water accumulated in the transverse drainage blind ditch 51 into the inspection well 43.

[0058] Corrosion-resistant steel ropes 10 are installed inside the circular pipe section and each section of the ditch body 42;

[0059] The two ends of the corrosion-resistant steel rope 10 installed inside the circular pipe section are respectively tied to the external steel components on the side wall of the central trench inspection well 35 at both ends of the circular pipe section, and the middle part of the corrosion-resistant steel rope 10 is located in the upper half of the inner cavity of the circular pipe section.

[0060] The two ends of the corrosion-resistant steel rope 10 located inside the ditch body 42 are respectively tied to the external steel components of the side walls of the ditch inspection wells 43 at both ends of the ditch body 42, and the middle part of the corrosion-resistant steel rope 10 is located in the upper half of the inner cavity of the ditch body 42.

[0061] A construction method for a combined central drainage system for expanding tunnel drainage capacity includes the following construction steps:

[0062] Step 1: Measure and mark the positions of the central ditch manhole 35, drainage ditch 41, and water ditch manhole 43 on the surface of road structure 2.

[0063] Step 2: Remove the asphalt surface layer 23 within a 50cm radius above and around the central ditch manhole 35, drainage ditch groove 41, and water ditch manhole 43, and cut the concrete pavement slab 22 within a 30cm radius above and around the central ditch manhole 35, drainage ditch groove 41, and water ditch manhole 43.

[0064] Step 3: Using the central ditch inspection well 35 as the dividing line, divide Tunnel 1 into multiple independent construction zones. Then, based on the availability of construction personnel and related machinery and equipment, carry out parallel operations in multiple non-adjacent construction zones until the construction of all drainage ditch bodies 42, concrete backfilling of ditch sides 44, and drainage components 5 is completed. Adjacent construction zones must not be operated simultaneously. During the construction process in Step 3, the monitoring and measurement of the tunnel 1 lining structure should be strengthened. If necessary, measures such as constructing locking pipe sheds at the foot of the lining sidewalls can be taken to ensure the stability of the lining structure.

[0065] Step 4: Construct the inspection well 43 and the irregular concrete backfill ditch side 47, and complete the installation of the water guide pipe B6 and T-shaped connecting steel pipe 7 during the construction process. Specifically, after the construction of the ditch body 42 on the upstream and downstream sides of the inspection well 43 is completed, the pouring construction of the inspection well 43 and the repair construction of the central ditch inspection well 35 will be carried out. The process is as follows:

[0066] First, the sidewall of the central trench inspection well 35 after partial excavation is repaired, and the sidewall of the central trench inspection well 43 near the water ditch is roughened and reinforced with steel bars as necessary.

[0067] Next, the tied reinforcing bars of the water ditch inspection well 43, the inner formwork of the water ditch inspection well 43, and the side formwork of the central ditch inspection well 35 are hoisted and placed into the excavated foundation pit. Then, special-shaped concrete is poured in one go to backfill the ditch side 47. During the pouring process, the water guide pipe B6 and the T-shaped connecting steel pipe 7 connecting the central ditch inspection well 35 and the water ditch inspection well 43 are installed.

[0068] Step 5: After all the new drainage ditches 4 in the construction zones have been completed, remove the construction waste in the new drainage ditches 4, and tie the two ends of the corrosion-resistant steel rope 10 to the external steel components on the side walls of the inspection wells 43 at both ends of the corresponding ditch body 42. Then install the precast reinforced concrete cover plate 45, the thickened precast reinforced concrete cover plate 46 and the anti-buoyancy and seepage-proof cover plate 36.

[0069] Step 6: Restore the concrete pavement slab 22 and asphalt surface layer 23 layer by layer from bottom to top. When pouring the concrete pavement slab 22, it is advisable to install longitudinal contraction joint tie rods 9 at the joint between the old and new pavement slabs.

[0070] The method for performing operations on a single construction zone in step three includes the following steps:

[0071] Step A: Set up construction barriers and safety cones at the boundaries of the construction zone for safety protection.

[0072] Step B: Open and remove the covers of the inspection wells 35 at the front and rear ends of the construction zone. Then, evenly wrap and adhere water-swellable sealing strips 362 to the side walls of the covers to transform them into anti-buoyancy and seepage-proof covers 36. In principle, the anti-buoyancy and seepage-proof covers 36 should be modified from the existing inspection well covers 35. If the existing inspection well covers 35 are damaged, a newly manufactured anti-buoyancy and seepage-proof cover 36 should be used directly.

[0073] Step C: Using the central trench inspection well 35 at the front and rear ends of the construction zone as the working surface, dredge the circular pipe trench 32 in the construction zone, and add a corrosion-resistant steel rope 10 in each circular pipe section. The two ends of the corrosion-resistant steel rope 10 are tied to the external steel components on the side wall of the central trench inspection well 35 at both ends of the corresponding circular pipe section.

[0074] Step D: The construction of the ditch body 42, the concrete backfill of the ditch sides 44, and the drainage components 5 is completed using a continuous flow operation method, specifically including the following steps:

[0075] Step a: Use a mechanical breaker to break the cut concrete pavement 22 and transport the concrete fragments away from the tunnel 1;

[0076] Step b: After the 10-meter working face of the delayed concrete pavement 22 is broken, the concrete structure of the invert backfill layer 21, the central ditch inspection well 35, and the invert filling (with invert section) or filling layer (without invert section) within the area of ​​the drainage ditch 41 to be excavated are mechanically removed, and the concrete fragments are transported away from the tunnel 1.

[0077] The excavation slope of the drainage ditch 41 to be excavated, near the existing tunnel center ditch 3, is determined based on its distance from the circular pipe ditch 32. On one hand, the distance from the excavation edge of the drainage ditch 41 to the circular pipe ditch 32 must be no less than 30cm (to avoid damage to the structure of the circular pipe ditch 32 during construction). On the other hand, the excavation edge of the drainage ditch 41 must intersect with the blind ditch 33 at the top of the ditch, and the height of the intersection must be no less than 20cm to ensure that the depth of the transverse water-guiding blind ditch 51 is no less than 20cm. In use, the bottom width of the drainage ditch 41 to be excavated is consistent with the width of the ditch body 42.

[0078] Step c: Excavate a 20-meter working face for the delayed drainage ditch 41, and complete the construction of the ditch body 42, concrete backfilling of the ditch sides 44, and drainage components 5 according to different situations. Specifically:

[0079] If the ditch body 42 is assembled from prefabricated ditch body components, the prefabricated ditch body components are hoisted and placed into the drainage ditch 41. Then, holes are drilled on the side wall of the ditch body 42 away from the existing tunnel center ditch 3. The cut transverse drainage pipe 8 is then connected to the ditch body 42 by means of a socket, and the water guide pipe A52 is installed into the reserved hole on the side wall of the ditch body 42. Next, the transverse water guide blind ditch 51 is filled with gravel wrapped with geotextile. The gap between the ditch body 42 and the two side walls of the drainage ditch 41 is backfilled with concrete symmetrically to form the concrete backfill ditch side 44.

[0080] If the ditch body 42 is a cast-in-place concrete structure, the tied ditch body 42 steel bars and the inner formwork of the ditch body 42 are first hoisted into the drainage ditch channel 41. Then, concrete is poured into the gap between the inner formwork and the drainage ditch channel 41. During the concrete pouring process, the cut transverse drainage pipe 8 is connected to the inner formwork by a sleeve. The transverse water guide blind ditch 51 is filled with gravel wrapped with geotextile. At the same time, the installation of the water guide pipe A52 is completed.

[0081] An operation method for a combined central drainage system for expanding the drainage capacity of a tunnel: a transverse drainage pipe 8 near the existing tunnel central ditch 3 draws groundwater into the existing tunnel central ditch 3, and a transverse drainage pipe 8 near the newly built drainage ditch 4 draws groundwater into the newly built drainage ditch 4.

[0082] When the water level in the existing tunnel central ditch 3 and the water level in the newly built drainage ditch 4 are both located below the transverse water guide blind ditch 51 and the water guide pipe B6, the existing tunnel central ditch 3 and the newly built drainage ditch 4 drain relatively independently.

[0083] When the drainage capacity of the existing tunnel central ditch 3 is insufficient or there is a local blockage, the water level in the existing tunnel central ditch 3 rises, and then the water in the circular pipe ditch 32 is back-pressed into the blind ditch 33 at the top of the ditch through the drain hole at the top of the ditch, and then flows into the newly built drainage ditch 4 through the transverse water guide blind ditch 51 and the water guide pipe A52, thereby realizing the joint drainage of the existing tunnel central ditch 3 and the newly built drainage ditch 4.

[0084] When the water level in the central ditch inspection well 35 rises due to blockage of the circular pipe 32 or insufficient drainage capacity, water can also be diverted to the ditch inspection well 43 through the water guide pipe B6.

[0085] When the water level in the central ditch inspection well 35 rises to the anti-buoyancy and seepage prevention cover plate 36, the water-swellable sealing strip 362 absorbs water and expands to prevent water from seeping upwards to the road surface. As the water-swellable sealing strip 362 expands, the anti-buoyancy and seepage prevention cover plate 36 fits tightly with the wellhead of the central ditch inspection well 35 to resist the buoyancy of the water.

[0086] When the existing central ditch 3 or the newly built drainage ditch 4 is blocked, the central ditch inspection well 35 or the water ditch inspection well 43 can be opened, and then the corrosion-resistant steel rope 10 can be used to drag the pipeline flushing equipment and maintenance equipment to carry out water ditch maintenance work on the existing central ditch 3 or the newly built drainage ditch 4.

Claims

1. A combined central drainage system for expanding the drainage capacity of a tunnel, characterized in that: The tunnel (1) is provided with a road structure (2), and the road structure (2) is provided with an existing tunnel central ditch (3) and a newly built drainage ditch (4) along the longitudinal direction of the tunnel (1). The newly built drainage ditch (4) is connected to the existing tunnel central ditch (3) through several drainage components (5).

2. The combined central drainage system for tunnel drainage capacity expansion according to claim 1, characterized in that: Multiple transverse drainage pipes (8) are provided on both sides of the drainage component (5) inside the road structure (2). One end of the transverse drainage pipe (8) is connected to the tunnel circumferential drainage pipe and the tunnel longitudinal drainage pipe, and the other end is connected to the existing tunnel central ditch (3) or the newly built drainage ditch (4). The road structure (2) includes an arch backfill layer (21), a concrete pavement slab (22), and an asphalt surface layer (23) laid sequentially from bottom to top.

3. The combined central drainage system for tunnel drainage capacity expansion according to claim 2, characterized in that: The existing tunnel central ditch (3) includes a central ditch channel (31) and a circular pipe channel (32). The central ditch channel (31) is located in the backfill layer (21) of the invert arch, and the circular pipe channel (32) is located in the central ditch channel (31). Geotextile-wrapped gravel is laid on the upper side of the circular pipe channel (32) in the central ditch channel (31) to form a blind ditch (33) at the top of the ditch. Multiple drainage holes are opened on the side of the circular pipe channel (32) facing the blind ditch (33) at the top of the ditch.

4. The combined central drainage system for tunnel drainage capacity expansion according to claim 3, characterized in that: The circular pipe trench (32) includes multiple circular pipe segments, and two adjacent circular pipe segments are connected through a central trench inspection well (35); The top of the central ditch inspection well (35) is provided with an anti-buoyancy and seepage prevention cover plate (36), which is located inside the concrete pavement slab (22), and the top surface of the anti-buoyancy and seepage prevention cover plate (36) is coplanar with the top surface of the concrete pavement slab (22). The anti-buoyancy and seepage-proof cover plate (36) includes a reinforced concrete cover plate body (361) and a water-swellable waterstop strip (362). The water-swellable waterstop strip (362) is evenly wrapped and adhered to the side wall of the reinforced concrete cover plate body (361).

5. The combined central drainage system for tunnel drainage capacity expansion according to claim 4, characterized in that: The newly constructed drainage ditch (4) is a rectangular drainage ditch, located on the side of the road surface with a higher cross slope of the road structure (2). It includes a drainage ditch channel (41) and a water ditch body (42) located in the drainage ditch channel (41). A concrete backfill ditch side (44) is provided between the water ditch body (42) and the two side walls of the drainage ditch channel (41). A precast reinforced concrete cover plate (45) is provided on the top of the water ditch body (42), and the precast reinforced concrete cover plate (45) is located on the underside of the concrete road surface (22).

6. The combined central drainage system for tunnel drainage capacity expansion according to claim 5, characterized in that: The ditch body (42) is provided in multiple sections, and two adjacent sections of the ditch body (42) are connected by a ditch inspection well (43). The ditch inspection well (43) is aligned with the central ditch inspection well (35) in the transverse direction of the tunnel (1). A special-shaped concrete backfill ditch side (47) is provided between the ditch inspection well (43) and the central ditch inspection well (35). Several water guide pipes B (6) connecting the upper part of the ditch inspection well (43) and the upper part of the central ditch inspection well (35) are provided in the special-shaped concrete backfill ditch side (47). The diameter of the water pipe B (6) is 160mm to 200mm. The spacing between several water pipes B (6) is 0.5m. The distance from the water pipe B (6) to the concrete pavement (22) is 30cm. The water pipe B (6) has a slope of not less than 2% from the side of the central ditch inspection well (35) to the side of the water ditch inspection well (43). The top of the drainage ditch inspection well (43) is provided with a thickened precast reinforced concrete cover plate (46). The thickened precast reinforced concrete cover plate (46) is located inside the concrete pavement slab (22), and the top surface of the thickened precast reinforced concrete cover plate (46) is coplanar with the top surface of the concrete pavement slab (22).

7. The combined central drainage system for tunnel drainage capacity expansion according to claim 6, characterized in that: The drainage component (5) includes a transverse water-conducting blind ditch (51) and multiple water-conducting pipes A (52). The transverse water-conducting blind ditch (51) is set longitudinally along the tunnel (1) in the concrete backfill ditch sidewall (44) between the ditch body (42) and the existing tunnel center ditch (3). The length of the transverse water-conducting blind ditch (51) is the same as the length of the ditch body (42). The transverse water-conducting blind ditch (51) is filled with gravel wrapped in geotextile. One end of the transverse water-conducting blind ditch (51) along the tunnel (1) is connected to the top blind ditch (33), and the other end extends to the outer wall of the ditch body (42). One end of the multiple water-conducting pipes A (52) extends into the ditch body (42), and the other end extends into the transverse water-conducting blind ditch (51). The geotextile in the transverse drainage blind ditch (51) is overlapped and connected with the geotextile in the top blind ditch (33). The width of the gravel filling in the transverse drainage blind ditch (51) on the transverse side of the tunnel (1) and replacing the original gravel space in the top blind ditch (33) is not less than 30cm.

8. The combined central drainage system for tunnel drainage capacity expansion according to claim 7, characterized in that: The transverse drainage blind ditch (51) is set with a downward slope of not less than 2% from the side of the existing tunnel central ditch (3) to the side of the ditch body (42). Multiple water pipes A (52) are set at a distance of 2m to 5m in the longitudinal direction of the tunnel (1). The diameter of the water pipe A (52) is 50mm to 110mm. The length of the water pipe A (52) extending into the transverse drainage blind ditch (51) is 5cm to 10cm. Multiple drainage holes are opened on the side wall of the water pipe A (52) located in the transverse drainage blind ditch (51).

9. The combined central drainage system for tunnel drainage capacity expansion according to claim 7, characterized in that: The irregular concrete backfill trench (47) blocks the transverse water-guiding blind trenches (51) on both sides of the water ditch inspection well (43), and the irregular concrete backfill trench (47) is provided with a T-shaped connecting steel pipe (7). The inlet of the T-shaped connecting steel pipe (7) extends into the transverse water-guiding blind trench (51) on the upstream side of the water ditch inspection well (43), one of the outlets extends into the transverse water-guiding blind trench (51) on the downstream side of the water ditch inspection well (43), and the other outlet extends into the water ditch inspection well (43). Multiple drainage holes are provided on the side wall of the T-shaped connecting steel pipe (7) extending into the transverse drainage blind ditch (51), and the T-shaped connecting steel pipe (7) is wrapped with geotextile.

10. The combined central drainage system for tunnel drainage capacity expansion according to claim 9, characterized in that: The circular pipe section and each section of the ditch body (42) are equipped with corrosion-resistant steel ropes (10); The two ends of the corrosion-resistant steel rope (10) installed in the circular pipe section are respectively tied to the external steel components on the side wall of the central trench inspection well (35) at both ends of the circular pipe section, and the middle part of the corrosion-resistant steel rope (10) is located in the upper half of the inner cavity of the circular pipe section. The two ends of the corrosion-resistant steel rope (10) located in the ditch body (42) are respectively tied to the external steel components of the side wall of the ditch inspection well (43) at both ends of the ditch body (42), and the middle part of the corrosion-resistant steel rope (10) is located in the upper half of the inner cavity of the ditch body (42).

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