Combined central drainage system for tunnel drainage capacity expansion and construction and operation method of combined central drainage system

Abstract

The invention discloses a combined central drainage system for tunnel drainage capacity expansion and a construction and operation method thereof, and belongs to the technical field of tunnel drainage systems. A road structure is arranged in the tunnel, an existing tunnel center ditch and a newly-built drainage ditch are arranged in the road structure in the longitudinal direction of the tunnel, and the newly-built drainage ditch is communicated with the existing tunnel center ditch through a plurality of drainage assemblies. The newly-built drainage ditch is communicated with the existing tunnel center ditch through the multiple drainage assemblies, then the combined type center drainage system is formed, the comprehensive drainage capacity is higher, the project scrap scale is effectively reduced, and the economical efficiency is better. Besides, in the construction period, only the road structure on the single side of the center ditch of the existing tunnel needs to be excavated, the center ditch of the existing tunnel is reserved, then the drainage requirement of the tunnel in the construction period can be effectively guaranteed, and due to the fact that the construction excavation position is located on the single side of the center ditch of the existing tunnel, the half-range traffic condition exists in the tunnel, and traffic organization in the construction period is facilitated.

Description

TECHNICAL FIELD

[0001] The present application relates to a combined central drainage system for expanding the drainage capacity of a tunnel and a construction and operation method thereof, and belongs to the technical field of tunnel drainage. BACKGROUND

[0002] With the extension of the tunnel operation time, a series of diseases such as road seepage and water gushing gradually appear, and the main reason for the occurrence of the above diseases is that the existing drainage system of the tunnel is blocked, resulting in poor drainage of the groundwater around the tunnel. In addition, the early built tunnel drainage system also has the problem of small design capacity, especially the early built tunnel round pipe type central ditch, which has a small overall pipe diameter and a relatively limited drainage capacity, and cannot effectively deal with the tunnel gushing water problem under the condition of concentrated rainfall in the rainy season. It is an important reason for the tunnel lining leakage and road water gushing in the rainy season. In view of the problem of insufficient drainage capacity of the existing tunnel central ditch, the construction scheme of excavating the existing round pipe type central ditch and then rebuilding a rectangular central ditch at the original position is generally used in engineering.

[0003] Although the above scheme can effectively improve the drainage capacity of the tunnel central ditch, it has the problems of difficult tunnel drainage during construction and complete interruption of tunnel traffic during construction, and there is also a certain economic loss of the complete scrap of the existing round pipe ditch. In view of the above situation, it has great practical significance to study a combined central drainage system for expanding the drainage capacity of a tunnel. SUMMARY

[0004] To solve the above technical problems, the present application provides a combined central drainage system for expanding the drainage capacity of a tunnel and a construction and operation method thereof.

[0005] The present application is realized by the following technical solutions: A combined central drainage system for expanding the drainage capacity of a tunnel, wherein the tunnel is provided with a road structure, the road structure is provided with an existing tunnel central ditch and a newly built drainage ditch along the longitudinal direction of the tunnel, and the newly built drainage ditch is communicated with the existing tunnel central ditch through a plurality of drainage assemblies.

[0006] A plurality of transverse drainage pipes are arranged on both sides of the drainage assembly in the road structure, one end of the transverse drainage pipe is communicated with a tunnel circumferential drainage pipe and a tunnel longitudinal drainage pipe, and the other end is communicated with the existing tunnel central ditch or the newly built drainage ditch. The road structure comprises a inverted arch backfill layer, a concrete pavement slab and an asphalt surface layer which are sequentially laid from bottom to top.

[0007] The existing tunnel center ditch comprises a center ditch groove and a circular pipe ditch, the center ditch groove is arranged in an inverted arch backfill layer, the circular pipe ditch is arranged in the center ditch groove, and a geotextile-wrapped gravel is arranged on the upside of the circular pipe ditch in the center ditch groove to form a blind ditch on the top of the center ditch.

[0008] The circular pipe ditch comprises a plurality of circular pipe segments, and adjacent two circular pipe segments are communicated through a center ditch inspection well.

[0009] The top of the center ditch inspection well is provided with an anti-floating and anti-seepage cover plate, the anti-floating and anti-seepage cover plate is located on the inner side of the concrete pavement slab, and the top surface of the anti-floating and anti-seepage cover plate is coplanar with the top surface of the concrete pavement slab. The anti-floating and anti-seepage cover plate comprises a reinforced concrete cover plate body and water-swelling sealing strips, and the water-swelling sealing strips are uniformly wound and adhered to the side wall of the reinforced concrete cover plate body.

[0010] The new drainage ditch is a rectangular drainage ditch, is arranged on the side with a higher horizontal slope of the road structure pavement, comprises a drainage ditch groove and a water ditch body arranged in the drainage ditch groove, and the water ditch body is provided with concrete backfill ditch sides between the two side walls of the drainage ditch groove, the top of the water ditch body is provided with a prefabricated reinforced concrete cover plate, and the prefabricated reinforced concrete cover plate is arranged on the lower side of the concrete pavement slab.

[0011] The water ditch body is provided with a plurality of sections, and adjacent two sections of the water ditch body are communicated through a water ditch inspection well, the water ditch inspection well is in one-to-one correspondence with the center ditch inspection well in the tunnel transverse direction, a special-shaped concrete backfill ditch side is arranged between the water ditch inspection well and the center ditch inspection well, and a plurality of water guide pipes B are arranged in the special-shaped concrete backfill ditch side and communicate the upper parts of the water ditch inspection well and the center ditch inspection well. The pipe diameter of the water guide pipe B is 160mm-200mm, the arrangement interval of the plurality of water guide pipes B is 0.5m, the distance from the water guide pipe B to the concrete pavement slab is 30cm, and the water guide pipe B is arranged to have a slope of not less than 2% from the side of the center ditch inspection well to the side of the water ditch inspection well. The top of the water ditch inspection well is provided with a thickened prefabricated reinforced concrete cover plate, the thickened prefabricated reinforced concrete cover plate is located on the inner side of the concrete pavement slab, and the top surface of the thickened prefabricated reinforced concrete cover plate is coplanar with the top surface of the concrete pavement slab.

[0012] The drainage assembly comprises a transverse water guide blind ditch and a plurality of water guide pipes A, the transverse water guide blind ditch is arranged in the concrete backfill ditch side between the water ditch body and the existing tunnel center ditch along the tunnel longitudinal direction, the length of the transverse water guide blind ditch is consistent with the length of the water ditch body, the transverse water guide blind ditch is filled with geotextile-wrapped gravel, one end of the transverse water guide blind ditch along the tunnel transverse direction is communicated with the blind ditch on the top of the center ditch, and the other end of the transverse water guide blind ditch extends to the outer side wall of the water ditch body, one end of the plurality of water guide pipes A extends into the water ditch body, and the other end of the plurality of water guide pipes A extends into the transverse water guide blind ditch. The geotextile in the transverse water diversion blind ditch is overlapped and connected with the geotextile in the blind ditch at the top of the ditch, and the gravel filling in the transverse water diversion blind ditch penetrates deeply in the transverse direction of the tunnel and replaces the original gravel space in the blind ditch at the top of the ditch by a width of not less than 30 cm.

[0013] The transverse water diversion blind ditch is set with a downward slope of not less than 2% from the central ditch side of the existing tunnel to the side of the ditch body. The spacing between the multiple water diversion pipes A in the longitudinal direction of the tunnel is 2m~5m, and the diameter of the water diversion pipe A is 50mm~110mm. The length of the water diversion pipe A extending into the transverse water diversion blind ditch is 5cm~10cm, and multiple drainage holes are opened on the side wall of the water diversion pipe A located in the transverse water diversion blind ditch.

[0014] The special-shaped concrete backfill ditch blocks the transverse water diversion blind ditch on both sides of the ditch inspection well, and a T-shaped connecting steel pipe is provided in the special-shaped concrete backfill ditch. The inlet of the T-shaped connecting steel pipe extends into the transverse water diversion blind ditch on the upstream side of the ditch inspection well, one of the outlets extends into the transverse water diversion blind ditch on the downstream side of the ditch inspection well, and the other outlet extends into the ditch inspection well; A plurality of drainage holes are provided on the side wall of the T-shaped connecting steel pipe extending into the transverse water diversion blind ditch, and the outside of the T-shaped connecting steel pipe is wrapped with geotextile.

[0015] The circular pipe section and each section of the ditch body are provided with corrosion-resistant steel ropes; The two ends of the corrosion-resistant steel rope arranged in the circular pipe section are correspondingly tied to the external steel components of the side walls of the central groove 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; The two ends of the corrosion-resistant steel rope arranged in the ditch body are correspondingly tied to the external steel components of the side walls of the ditch inspection wells at both ends of the ditch body, and the middle part of the corrosion-resistant steel rope is located in the upper half of the inner cavity of the ditch body.

[0016] A construction method for a combined central drainage system for expanding tunnel drainage capacity includes the following construction steps: Step 1: Measure and lay out the lines, marking the locations of the center ditch inspection well, drainage ditch grooves, and ditch inspection wells on the road surface; Step 2: Remove the asphalt surface layer within 50 cm above and around the central ditch inspection well, drainage ditch grooves, and water ditch inspection well, and cut the concrete road slab within 30 cm above and around the central ditch inspection well, drainage ditch grooves, and water ditch inspection well; Step three, divide the tunnel into multiple independent construction zones with the central inspection well as the boundary, then parallel operation multiple non-adjacent construction zones according to the construction personnel and related mechanical equipment, until all the water ditch body, concrete backfill ditch and drainage components construction are completed, adjacent construction zones cannot operate at the same time; Step four, construction of water ditch inspection well and special-shaped concrete backfill ditch, and installation of water guide pipe B and T-shaped connecting steel pipe during the construction process; Step five, after all the new drainage ditches in the construction zones are completed, remove the construction waste in the new drainage ditches, and then bundle the two ends of the corrosion-resistant steel rope on the outer steel members of the side walls of the water ditch inspection wells at both ends of the water ditch body, and then install the prefabricated reinforced concrete cover plate, thickened prefabricated reinforced concrete cover plate and anti-floating impermeable cover plate; Step six, restore the concrete road panel and asphalt surface layer layer by layer from bottom to top.

[0017] The method for operating a single construction zone in step three includes the following steps: Step A, set up construction fences and safety cones at the boundaries of the construction zone for safety protection; Step B, open and remove the cover plates of the central inspection wells at the front and rear ends of the construction zone, then evenly wrap and stick water-swelling sealing strips on the side walls of the cover plates to transform them into anti-floating impermeable cover plates; Step C, take the central inspection wells at the front and rear ends of the construction zone as the working face, dredge the circular pipe ditches in the construction zone, and add a corrosion-resistant steel rope in each circular pipe section, with the two ends of the corrosion-resistant steel rope bundled on the outer steel members of the side walls of the central inspection wells at both ends of the corresponding circular pipe section; Step D, complete the water ditch body, concrete backfill ditch and drainage component construction by using the flow water operation method, which includes the following steps: Step a, use a mechanical breaking hammer to break the concrete road panel that has been cut, and transport the concrete fragments out of the tunnel; Step b, lag 10 meters behind the concrete road panel breaking working face, mechanically chisel the inverted arch backfill layer and the local central inspection well in the range of the to-be-excavated drainage ditch groove, and transport the concrete fragments out of the tunnel; Wherein, the excavation slope rate of the to-be-excavated drainage ditch groove near the existing tunnel central inspection well is determined according to the distance between the to-be-excavated drainage ditch groove and the circular pipe ditch, on the one hand, the distance from the excavation line of the to-be-excavated drainage ditch groove to the circular pipe ditch is not less than 30 cm, on the other hand, the excavation line of the to-be-excavated drainage ditch groove intersects with the blind ditch at the top, and the height of the intersection part is not less than 20 cm, so as to ensure that the depth of the transverse water guide blind ditch is not less than 20 cm; Step c, the lagging drainage ditch groove excavation working face 20 meters, complete the ditch body, concrete backfill ditch side and drainage component construction, specifically: If the ditch body is made of prefabricated ditch body components, the prefabricated ditch body components are hoisted and placed into the drainage ditch groove, then holes are drilled on the side wall of the ditch body away from the existing tunnel center ditch, then the cut-off transverse drainage pipe is connected into the ditch body by sleeving, and the water guide pipe A is installed into the reserved hole on the side wall of the ditch body, then the soil wrapped gravel is filled into the transverse water guide blind ditch, and the gap between the ditch body and the two side walls of the drainage ditch groove is backfilled with concrete to form the concrete backfill ditch side; If the ditch body is a concrete cast-in-place structure, the bundled ditch body reinforcement and the ditch body inner formwork are hoisted into the drainage ditch groove first, then the gap between the inner formwork and the drainage ditch groove is constructed by pouring concrete, and in the process of concrete pouring construction, the cut-off transverse drainage pipe is connected into the inner formwork by sleeving, the soil wrapped gravel is filled into the transverse water guide blind ditch, and the water guide pipe A installation work is completed at the same time.

[0018] A running method of a combined central drainage system for expanding the drainage capacity of a tunnel, the transverse drainage pipe near the existing tunnel center ditch guides and drains underground water into the existing tunnel center ditch, and the transverse drainage pipe near the newly built drainage ditch guides and drains underground water into the newly built drainage ditch; When the water level in the existing tunnel center ditch and the water level in the newly built drainage ditch are both located below the transverse water guide blind ditch and the water guide pipe B, the existing tunnel center ditch and the newly built drainage ditch are relatively independent in drainage; When the drainage capacity of the existing tunnel center ditch is insufficient or local blockage occurs, the water level in the existing tunnel center ditch rises, and then the water in the circular pipe ditch is back-pressed into the top blind ditch through the water outlet hole at the top of the circular pipe ditch, and then flows into the newly built drainage ditch through the transverse water guide blind ditch and the water guide pipe A, thereby realizing the combined drainage of the existing tunnel center ditch and the newly built drainage ditch; When the water level in the center ditch inspection well rises due to the blockage or insufficient drainage capacity of the circular pipe ditch, the water can also be guided into the water ditch inspection well through the water guide pipe B; When the water level in the center ditch inspection well rises to the anti-floating and anti-seepage cover plate, the water-swelling waterstop absorbs water to prevent water from seeping upward to the road surface, and because the water-swelling waterstop swells, the anti-floating and anti-seepage cover plate tightly fits the well mouth of the center ditch inspection well to resist the upward floating force of water; When the existing tunnel center ditch or the newly built drainage ditch is blocked, the center ditch inspection well or the water ditch inspection well can be opened, and then the pipeline flushing equipment and the maintenance equipment are dragged by the corrosion-resistant steel rope for water ditch maintenance work of the existing tunnel center ditch or the newly built drainage ditch.

[0019] The application has the beneficial effects that: the newly-built drainage ditch is communicated with the existing tunnel center ditch through multiple drainage assemblies, and then a combined central drainage system is formed, compared with the conventional scheme of demolishing the existing tunnel center ditch for reconstruction, the combined central drainage system has stronger comprehensive drainage capacity, effectively reduces the engineering scrap scale, and has better economy. In addition, only the road structure on one side of the existing tunnel center ditch needs to be excavated during construction, the existing tunnel center ditch is retained, thereby effectively guaranteeing the drainage demand of the tunnel during construction, and because the construction excavation is located on one side of the existing tunnel center ditch, there is a half-width traffic condition in the tunnel, which is conducive to traffic organization during construction. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 is a schematic view of a transverse section of the water ditch body of the application; Figure 2 is a schematic view of the assembly structure of the road structure, the existing tunnel center ditch, the newly-built drainage ditch, the drainage assembly, the transverse drainage pipe and the pull rod of the application; Figure 3 is a schematic view of a transverse section of the water ditch inspection well of the application; Figure 4 is a schematic view of the assembly structure of the road structure, the center ditch inspection well, the water ditch inspection well, the water guide pipe B, the T-shaped connecting steel pipe and the like of the application; Figure 5 is a schematic view of the structure of the anti-floating and anti-seepage cover plate of the application; Figure 6 is a top view of the existing tunnel center ditch, the newly-built drainage ditch and the drainage assembly of the application after construction is completed; Figure 7 is a partial top view of the water ditch inspection well of the existing tunnel center ditch, the newly-built drainage ditch and the drainage assembly of the application after construction is completed; Figure 8 is a schematic view of the assembly structure of the special-shaped concrete backfill ditch, the transverse water guide blind ditch and the T-shaped connecting steel pipe of the application.

[0021] In the figure: 1-tunnel, 2-road structure, 21-inverted arch backfill layer, 22-concrete road slab, 23-asphalt surface layer, 3-existing tunnel center ditch, 31-center ditch groove, 32-circular pipe ditch, 33-ditch top blind ditch, 34-concrete foundation, 35-center ditch inspection well, 36-anti-floating and anti-seepage cover plate, 361-reinforced concrete cover plate body, 362-water-expanding water stop strip, 4-new drainage ditch, 41-drainage ditch groove, 42-ditch body, 43-ditch inspection well, 44-concrete backfill ditch side, 45-precast reinforced concrete cover plate, 46-thickened precast reinforced concrete cover plate, 47-special-shaped concrete backfill ditch side, 5-drainage assembly, 51-transverse water diversion blind ditch, 52-water diversion pipe A, 6-water diversion pipe B, 7-T-type connecting steel pipe, 8-transverse drainage pipe, 9-longitudinal contraction joint tie rod, 10-corrosion-resistant steel rope. DETAILED DESCRIPTION

[0022] The technical solution of the present invention is further described below, but the scope of protection claimed is not limited to the description.

[0023] like Figures 1 to 8 As shown, the present invention describes a combined central drainage system for expanding the drainage capacity of a tunnel. The tunnel 1 is provided with a road structure 2. The road structure 2 is provided with an existing tunnel center 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 center ditch 3 through a number of drainage components 5. The newly built drainage ditch 4 is connected to the existing tunnel center ditch 3 through a plurality of drainage components 5, thereby forming a combined central drainage system. Compared with the conventional solution of demolishing the existing tunnel center ditch 3 for reconstruction, its comprehensive drainage capacity is stronger, the scale of project scrapping is effectively reduced, and the economy is better. In addition, during the construction period, only the road structure 2 on one side of the existing tunnel center ditch 3 needs to be excavated, and the existing tunnel center ditch 3 can be retained, thereby effectively guaranteeing the drainage needs of the tunnel 1 during the construction period. Moreover, since the construction excavation site is located on one side of the existing tunnel center ditch 3, there is a half-width traffic condition in the tunnel 1, which is beneficial to the traffic organization during the construction period.

[0024] A plurality of transverse drainage pipes 8 are provided on both sides of the drainage assembly 5 in the road structure 2. One end of the transverse drainage pipe 8 is connected to the tunnel annular 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 inverted arch backfill layer 21, a concrete road 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 center ditch 3 or the newly built drainage ditch 4.

[0025] The existing tunnel center ditch 3 comprises a center ditch groove 31 and a circular pipe ditch 32, the center ditch groove 31 is arranged in the inverted arch backfill layer 21, the circular pipe ditch 32 is arranged in the center ditch groove 31, the top blind ditch 33 is formed by laying the geotextile wrapped gravel on the upside of the circular pipe ditch 32 in the center ditch groove 31, and a plurality of water discharge holes are arranged on the side of the circular pipe ditch 32 facing the top blind ditch 33. The pipe wall of the circular pipe ditch 32 is a reinforced concrete structure.

[0026] The circular pipe ditch 32 comprises a plurality of circular pipe sections, and adjacent two circular pipe sections are communicated through the center ditch inspection well 35.

[0027] The top of the center ditch inspection well 35 is provided with an anti-floating and anti-seepage cover plate 36, the anti-floating and anti-seepage cover plate 36 is located on the inner side of the concrete pavement slab 22, and the top surface of the anti-floating and anti-seepage cover plate 36 is coplanar with the top surface of the concrete pavement slab 22. The anti-floating and anti-seepage cover plate 36 comprises a reinforced concrete cover plate body 361 and a water-swelling waterstop 362, the water-swelling waterstop 362 is uniformly wound and adhered on the side wall of the reinforced concrete cover plate body 361. The anti-floating and anti-seepage cover plate 36 is located on the inner side of the concrete pavement slab 22, when the existing tunnel center ditch 3 needs to be maintained, the asphalt surface layer 23 is thrown away, and the anti-floating and anti-seepage cover plate 36 can be opened.

[0028] The prerequisite for the combined drainage of the existing tunnel center ditch 3 and the newly-built drainage ditch is that the existing tunnel center ditch 3 is blocked or has insufficient drainage capacity, so that the water level of the existing tunnel center ditch 3 rises. Among them, the circular pipe section is deeply buried below the concrete pavement slab 22, and is drained through the transverse water guide blind ditch 51, so that the risk of water accumulation and uplift of the pavement structure above is small; and the cover plate of the center ditch inspection well 35 is directly arranged at the bottom of the asphalt pavement, and if the water level rises, it may cause water to gush out of the pavement, the cover plate to float up and the pavement to uplift, etc.

[0029] In order to solve the problems of upward seepage of the center ditch inspection well 35 and uplift of the cover plate under the condition of rapid rise of the water level, the anti-floating and anti-seepage cover plate 36 is designed, and the advantages are as follows: When the water level in the center ditch inspection well 35 does not rise to the elevation of the anti-floating and anti-seepage cover plate 36, the water-swelling waterstop 362 is in a normal state, at this time, there is a small gap between the anti-floating and anti-seepage cover plate 36 and the edge of the well mouth of the center ditch inspection well 35, and the anti-floating and anti-seepage cover plate 36 can be relatively easily opened during operation and maintenance; When the water level rises to the elevation of the anti-floating and anti-seepage cover plate 36, the water-swelling waterstop 362 swells after being wetted, at this time, the anti-floating and anti-seepage cover plate 36 is closely attached to the well mouth of the center ditch inspection well 35, on the one hand, it can prevent water from seeping back to the pavement, and on the other hand, by increasing the friction resistance between the anti-floating and anti-seepage cover plate 36 and the well mouth of the center ditch inspection well 35, the risk of floating of the anti-floating and anti-seepage cover plate 36 under the action of water pressure is significantly reduced.

[0030] The new drainage ditch 4 is a rectangular drainage ditch, which is arranged at the side with higher road surface transverse slope of the road structure 2, and includes a drainage ditch groove 41 and a ditch body 42 arranged in the drainage ditch groove 41. The ditch body 42 is arranged between the two side walls of the drainage ditch groove 41 and is provided with a concrete backfill ditch side 44. The top of the ditch body 42 is provided with a prefabricated reinforced concrete cover plate 45, and the prefabricated reinforced concrete cover plate 45 is arranged at the lower side of the concrete pavement slab 22. The new drainage ditch 4 is built at the side with higher road surface transverse slope of the road structure 2, and the distance from the bottom of the tunnel 1 to the top surface of the road structure 2 is relatively larger at this side, which can ensure the setting space of the new drainage ditch 4. In addition, under the premise of ensuring that the excavation construction of the new drainage ditch 4 does not affect the structural stability of the existing tunnel center ditch 3, the transverse distance between the new drainage ditch 4 and the existing tunnel center ditch 3 should be as small as possible, so as to achieve the purpose of minimizing the setting width of the drainage assembly 5.

[0031] The ditch body 42 is arranged in multiple sections, and the adjacent two sections of the ditch body 42 are connected through a ditch inspection well 43. The ditch inspection well 43 is in one-to-one alignment with the center ditch inspection well 35 in the transverse direction of the tunnel 1. An irregular concrete backfill ditch side 47 is arranged between the ditch inspection well 43 and the center ditch inspection well 35. The irregular concrete backfill ditch side 47 is provided with a plurality of water guide pipes B6 for connecting the upper part of the ditch inspection well 43 and the upper part of the center ditch inspection well 35; The pipe diameter of the water guide pipe B6 is 160mm-200mm, the setting distance of the plurality of water guide pipes B6 is 0.5m, the distance from the water guide pipe B6 to the concrete pavement slab 22 is 30cm, and the water guide pipe B6 is arranged with a slope of not less than 2% from the side of the center ditch inspection well 35 to the side of the ditch inspection well 43; The top of the ditch inspection well 43 is provided with a thickened prefabricated reinforced concrete cover plate 46, which is located at the inner side of the concrete pavement slab 22, and the top surface of the thickened prefabricated reinforced concrete cover plate 46 is coplanar with the top surface of the concrete pavement slab 22.

[0032] The prefabricated reinforced concrete cover plate 45 is arranged at the lower side of the concrete pavement slab 22, and if it needs to be opened in the later period, the asphalt surface layer 23 and the concrete pavement slab 22 need to be removed. Generally, it will not be opened. Since the upper side has the concrete pavement slab 22 to bear the vehicle load, it does not need to be thickened. The thickened prefabricated reinforced concrete cover plate 46 is located at the inner side of the concrete pavement slab 22 and can be opened by removing only the asphalt surface layer 23. It needs to replace the concrete pavement slab 22 to bear the vehicle load, so it needs to be thickened.

[0033] The drainage assembly 5 comprises a transverse water guide blind ditch 51 and a plurality of water guide pipes A52, the transverse water guide blind ditch 51 is longitudinally arranged in the concrete backfill slope 44 between the water ditch body 42 and the existing tunnel center ditch 3, the length of the transverse water guide blind ditch 51 is consistent with the length of the water ditch body 42, the transverse water guide blind ditch 51 is filled with geotextile wrapped gravel, one end of the transverse water guide blind ditch 51 is communicated with the blind ditch 33 on the tunnel 1 transverse side, and the other end extends to the outer side wall of the water ditch body 42, one end of the plurality of water guide pipes A52 extends into the water ditch body 42, and the other end extends into the transverse water guide blind ditch 51. The geotextile in the transverse water guide blind ditch 51 is connected with the geotextile in the blind ditch 33, and the gravel in the transverse water guide blind ditch 51 is filled to a depth of not less than 30 cm to replace the width of the original gravel space in the blind ditch 33.

[0034] The transverse water guide blind ditch 51 is arranged with a slope of not less than 2% from the side of the existing tunnel center ditch 3 to the side of the water ditch body 42, the spacing of the plurality of water guide pipes A52 in the longitudinal direction of the tunnel 1 is 2m~5m, the diameter of the water guide pipe A52 is 50mm~110mm, the length of the water guide pipe A52 extending into the transverse water guide blind ditch 51 is 5cm~10cm, and a plurality of water outlet holes are arranged on the side wall of the water guide pipe A52 in the transverse water guide blind ditch 51. The transverse water guide blind ditch 51 is arranged with a slope of not less than 2% from the side of the existing tunnel center ditch 3 to the side of the water ditch body 42, which facilitates the flow of water in the transverse water guide blind ditch 51 to the newly built drainage ditch 4.

[0035] The special-shaped concrete backfill slope 47 blocks the transverse water guide blind ditch 51 on both sides of the water ditch inspection well 43, and a T-shaped connecting steel pipe 7 is arranged in the special-shaped concrete backfill slope 47, one end of the T-shaped connecting steel pipe 7 extends into the transverse water guide blind ditch 51 on the upstream side of the water ditch inspection well 43, one end of the T-shaped connecting steel pipe 7 extends into the transverse water guide blind ditch 51 on the downstream side of the water ditch inspection well 43, and the other end of the T-shaped connecting steel pipe 7 extends into the water ditch inspection well 43. A plurality of water outlet holes are arranged on the side wall of the T-shaped connecting steel pipe 7 extending into the transverse water guide blind ditch 51, and the T-shaped connecting steel pipe 7 is wrapped with geotextile.

[0036] Since the special-shaped concrete backfill slope 47 blocks the transverse water guide blind ditch 51 on both sides of the water ditch inspection well 43, in order to ensure the smoothness of the drainage of the transverse water guide blind ditch 51 and avoid local water accumulation, a T-shaped connecting steel pipe 7 is arranged in the T-shaped connecting steel pipe 7, the bottom surface elevation of the T-shaped connecting steel pipe 7 is matched with the bottom surface elevation of the transverse water guide blind ditch 51, and the T-shaped connecting steel pipe 7 can ensure the communication between the transverse water guide blind ditches 51 and can directly drain the water in the transverse water guide blind ditches 51 into the water ditch inspection well 43.

[0037] The corrosion-resistant steel rope 10 is arranged in the circular pipe section and the water ditch body 42, and the two ends of the corrosion-resistant steel rope 10 are bound to the outer steel members of the side walls of the central ditch inspection well 35 at the two 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 arranged in the water ditch body 42 are bound to the outer steel members of the side walls of the water ditch inspection well 43 at the two ends of the water 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 water ditch body 42. The two ends of the corrosion-resistant steel rope 10 arranged in the water ditch body 42 are bound to the outer steel members of the side walls of the water ditch inspection well 43 at the two ends of the water 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 water ditch body 42.

[0038] A construction method of a combined central drainage system for expanding the drainage capacity of a tunnel, comprising the following construction steps: Step one, measurement and line laying, marking the positions of the central ditch inspection well 35, the drainage ditch groove 41 and the water ditch inspection well 43 on the surface of the road structure 2.

[0039] Step two, removing the asphalt surface layer 23 within a range of 50 cm around the central ditch inspection well 35, the drainage ditch groove 41 and the water ditch inspection well 43, and cutting the concrete road panel 22 within a range of 30 cm around the central ditch inspection well 35, the drainage ditch groove 41 and the water ditch inspection well 43.

[0040] Step three, dividing the tunnel 1 into multiple independent construction zones with the central ditch inspection well 35 as the boundary, then performing parallel work on multiple non-adjacent construction zones according to the allocation of construction personnel and related mechanical equipment, until the construction of all water ditch bodies 42, concrete backfill ditch sides 44 and drainage assemblies 5 is completed, and adjacent construction zones cannot be operated at the same time. During the construction of step three, the monitoring and measurement of the lining structure of the tunnel 1 should be strengthened, and measures such as constructing a lock foot pipe shed at the foot of the lining side wall can be taken when necessary to ensure the stability of the lining structure.

[0041] Step four, constructing the water ditch inspection well 43 and the special-shaped concrete backfill ditch side 47, and installing the water guide pipe B6 and the T-shaped connecting steel pipe 7 during the construction process. Specifically, after the water ditch bodies 42 on the upstream and downstream sides of the water ditch inspection well 43 are constructed, the water ditch inspection well 43 is poured and constructed, and the central ditch inspection well 35 is repaired, and the process is as follows: First, the side wall of the locally excavated central ditch inspection well 35 is trimmed, and the necessary surface chiseling and anchoring treatment is performed on the side wall near the water ditch inspection well 43; Secondly, the reinforced water inspection well 43, the inner form of the water inspection well 43 and the side form of the center inspection well 35 are hoisted and placed in the excavated foundation pit, and then the special-shaped concrete backfill ditch side 47 is poured in one time. During the pouring process, the water guide pipe B6 and the T-shaped connecting steel pipe 7 connecting the center inspection well 35 and the water inspection well 43 are installed.

[0042] Step five, after the construction of all the new drainage ditches 4 in the construction partition is completed, the construction waste in the new drainage ditch 4 is removed, and the two ends of the corrosion-resistant steel rope 10 are correspondingly bound on the outer steel members of the side wall of the water inspection well 43 at both ends of the water ditch body 42, and then the prefabricated reinforced concrete cover plate 45, the thickened prefabricated reinforced concrete cover plate 46 and the anti-floating and anti-seepage cover plate 36 are installed. Step six, restore the concrete pavement slab 22 and the asphalt surface layer 23 layer by layer from bottom to top. When pouring the concrete pavement slab 22, it is appropriate to set the longitudinal shrinkage joint pull rod 9 at the joint position of the new and old pavement slabs.

[0043] The method of step three for working on a single construction partition includes the following steps: Step A, set up construction fences and safety cones at the boundaries of the construction partition for safety protection.

[0044] Step B, open and remove the cover plates of the center inspection well 35 at the front and rear ends of the construction partition, and then uniformly wrap and stick the water-swelling sealing strip 362 on the side wall of the cover plate to transform it into an anti-floating and anti-seepage cover plate 36. The anti-floating and anti-seepage cover plate 36 is originally transformed from the original center inspection well 35 cover plate. If the original center inspection well 35 cover plate is damaged, a newly made anti-floating and anti-seepage cover plate 36 is directly used.

[0045] Step C, taking the center inspection well 35 at the front and rear ends of the construction partition as the working face, the circular pipe ditch 32 in the construction partition is dredged, and a corrosion-resistant steel rope 10 is additionally arranged in each circular pipe section. The two ends of the corrosion-resistant steel rope 10 are correspondingly bound on the outer steel members of the side wall of the center inspection well 35 at both ends of the corresponding circular pipe section.

[0046] Step D, the water ditch body 42, the concrete backfill ditch side 44 and the drainage assembly 5 are constructed by using the flow water operation mode, which includes the following steps: Step a, the concrete pavement slab 22 that has been cut is broken by using a mechanical breaking hammer, and the concrete fragments are transported out of the tunnel 1; Step b, 10 meters behind the broken working face of the concrete pavement slab 22, the concrete structure of the inverted arch backfill layer 21, the local center inspection well 35 and the inverted arch filling (with inverted arch section) or filling layer (without inverted arch section) in the range to be excavated are mechanically chiseled, and the concrete fragments are transported out of the tunnel 1; The excavation slope rate of the to-be-excavated drainage ditch groove 41 near one side of the existing tunnel center ditch 3 is determined according to the distance between the to-be-excavated drainage ditch groove 41 and the circular pipe ditch 32, on the one hand, the distance between the excavation edge line of the to-be-excavated drainage ditch groove 41 and the circular pipe ditch 32 is required to be not less than 30 cm (the purpose is to avoid damage to the structure of the circular pipe ditch 32 caused by construction), on the other hand, the excavation edge line of the to-be-excavated drainage ditch groove 41 is required to intersect with the blind ditch 33 on the top of the ditch, and the height of the intersection part is required to be not less than 20 cm, so as to ensure that the depth of the transverse water guide blind ditch 51 is not less than 20 cm. In use, the bottom width of the to-be-excavated drainage ditch groove 41 is consistent with the width of the ditch body 42.

[0047] Step c, the lagging drainage ditch groove 41 excavates the working face 20 meters, and the ditch body 42, the concrete backfill ditch side 44 and the drainage assembly 5 are constructed in different cases, specifically: If the ditch body 42 is formed by splicing prefabricated ditch body components, the prefabricated ditch body components are hoisted and placed into the drainage ditch groove 41, then holes are drilled on the side wall of the ditch body 42 away from the existing tunnel center ditch 3, then the cut transverse drainage pipe 8 is connected into the ditch body 42 in a sleeved manner, and the water guide pipe A52 is installed into the reserved hole on the side wall of the ditch body 42, then the transverse water guide blind ditch 51 is filled with gravel wrapped with geotextile, and the gap between the ditch body 42 and the two side walls of the drainage ditch groove 41 is backfilled with concrete to form the concrete backfill ditch side 44; If the ditch body 42 is a concrete cast-in-place structure, the bundled steel reinforcement of the ditch body 42 and the inner formwork of the ditch body 42 are hoisted into the drainage ditch groove 41, then the gap between the inner formwork and the drainage ditch groove 41 is constructed by pouring concrete, and in the process of concrete pouring construction, the cut transverse drainage pipe 8 is connected into the inner formwork in a sleeved manner, the transverse water guide blind ditch 51 is filled with gravel wrapped with geotextile, and the water guide pipe A52 installation work is completed at the same time.

[0048] An operation method of a combined central drainage system for expanding the drainage capacity of a tunnel, the transverse drainage pipe 8 near the existing tunnel center ditch 3 guides and drains underground water into the existing tunnel center ditch 3, and the transverse drainage pipe 8 near the newly-built drainage ditch 4 guides and drains underground water into the newly-built drainage ditch 4; When the water level in the existing tunnel center ditch 3 and the water level in the newly-built drainage ditch 4 are both located on the lower side of the transverse water guide blind ditch 51 and the water guide pipe B6, the existing tunnel center ditch 3 and the newly-built drainage ditch 4 are relatively independent drainage; When the drainage capacity of the existing tunnel center ditch 3 is insufficient or local blockage occurs, the water level in the existing tunnel center ditch 3 rises, and then the water in the circular pipe ditch 32 is reversely pressed into the blind ditch 33 on the top of the circular pipe ditch 32 through the drainage hole on the top, 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 combined drainage of the existing tunnel center ditch 3 and the newly-built drainage ditch 4. When the water level rises due to the blockage or insufficient drainage capacity of the circular pipe ditch 32, the water can also be drained into the water ditch inspection well 43 through the water guide pipe B6; When the water level in the center ditch inspection well 35 rises to the anti-floating and anti-seepage cover plate 36, the water-swelling waterstop 362 swells to prevent water from seeping upward to the road surface, and because the water-swelling waterstop 362 swells, the anti-floating and anti-seepage cover plate 36 closely fits the well mouth of the center ditch inspection well 35 to resist the upward floating force of the water; When the existing tunnel center ditch 3 or the newly built drainage ditch 4 is blocked, the center ditch inspection well 35 or the water ditch inspection well 43 can be opened, and then the corrosion-resistant steel rope 10 is used to pull the pipeline flushing equipment and the maintenance equipment to carry out water ditch maintenance work on the existing tunnel center ditch 3 or the newly built drainage ditch 4.

Claims

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

2. The combined central drainage system for expanding tunnel drainage capacity according to claim 1, characterized in that: A plurality of transverse drainage pipes (8) are provided on both sides of the drainage assembly (5) in the road structure (2), one end of the transverse drainage pipe (8) is connected to the tunnel annular 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) comprises an inverted arch backfill layer (21), a concrete road panel (22) and an asphalt surface layer (23) which are laid sequentially from bottom to top.

3. The combined central drainage system for expanding tunnel drainage capacity according to claim 2, characterized in that: The existing tunnel center trench (3) comprises a center trench groove (31) and a circular pipe trench (32), wherein the center trench groove (31) is arranged in the inverted arch backfill layer (21), and the circular pipe trench (32) is arranged in the center trench groove (31), and gravel wrapped with geotextile is laid on the upper side of the circular pipe trench (32) in the center trench groove (31) to form a trench top blind trench (33), and a plurality of drainage holes are opened on the side of the circular pipe trench (32) facing the trench top blind trench (33).

4. The combined central drainage system for expanding tunnel drainage capacity according to claim 3, characterized in that: The circular pipe trench (32) includes a plurality of circular pipe sections, and two adjacent circular pipe sections are connected through a central trench inspection well (35).

5. The combined central drainage system for expanding tunnel drainage capacity according to claim 4, characterized in that: An anti-floating and anti-seepage cover plate (36) is provided on the top of the central ditch inspection well (35), the anti-floating and anti-seepage cover plate (36) is located on the inner side of the concrete road panel (22), and the top surface of the anti-floating and anti-seepage cover plate (36) is coplanar with the top surface of the concrete road panel (22); The anti-floating and anti-seepage cover plate (36) comprises a reinforced concrete cover plate body (361) and a water-swelling waterstop strip (362), wherein the water-swelling waterstop strip (362) is evenly wound around and adhered to the side wall of the reinforced concrete cover plate body (361).

6. The combined central drainage system for expanding tunnel drainage capacity according to claim 4, characterized in that: The newly built drainage ditch (4) is a rectangular drainage ditch, which is arranged on the side of the road surface with a higher transverse slope of the road structure (2), and includes a drainage ditch groove (41) and a ditch body (42) arranged in the drainage ditch groove (41). Concrete backfill ditch sides (44) are provided between the ditch body (42) and the two side walls of the drainage ditch groove (41). A prefabricated reinforced concrete cover plate (45) is provided on the top of the ditch body (42), and the prefabricated reinforced concrete cover plate (45) is provided on the lower side of the concrete road panel (22).

7. The combined central drainage system for expanding tunnel drainage capacity according to claim 6, characterized in that: The ditch body (42) is provided with multiple sections, and two adjacent sections of the ditch body (42) are connected through 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). A plurality of water guide pipes B (6) are provided in the special-shaped concrete backfill ditch side (47) to connect the upper part of the ditch inspection well (43) and the upper part of the central ditch inspection well (35); The diameter of the water pipe B (6) is 160 mm to 200 mm, the spacing between the plurality of water pipes B (6) is 0.5 m, the distance between the water pipe B (6) and the concrete road slab (22) is 30 cm, and the water pipe B (6) is provided with a downward slope of not less than 2% from the side of the central ditch inspection well (35) to the side of the ditch inspection well (43); A thickened prefabricated reinforced concrete cover plate (46) is provided on the top of the ditch inspection well (43). The thickened prefabricated reinforced concrete cover plate (46) is located on the inner side of the concrete road panel (22), and the top surface of the thickened prefabricated reinforced concrete cover plate (46) is coplanar with the top surface of the concrete road panel (22).

8. The combined central drainage system for expanding tunnel drainage capacity according to claim 7, characterized in that: The drainage assembly (5) includes a transverse water-guiding blind ditch (51) and a plurality of water-guiding pipes A (52). The transverse water-guiding blind ditch (51) is arranged in the concrete backfill ditch wall (44) between the ditch body (42) and the existing tunnel center ditch (3) along the longitudinal direction of the tunnel (1), and the length of the transverse water-guiding blind ditch (51) is consistent with the length of the ditch body (42). The transverse water-guiding blind ditch (51) is filled with gravel wrapped with geotextile. One end of the transverse water-guiding blind ditch (51) along the transverse direction of the tunnel (1) is connected to the ditch top blind ditch (33), and the other end extends to the outer wall of the ditch body (42). One end of the plurality of water-guiding pipes A (52) extends into the ditch body (42), and the other end extends into the transverse water-guiding blind ditch (51); The geotextile in the transverse water diversion blind ditch (51) is overlapped and connected with the geotextile in the blind ditch at the top (33), and the gravel in the transverse water diversion blind ditch (51) is filled deep into and replaces the original gravel space in the blind ditch at the top (33) in the transverse direction of the tunnel (1), with a width of not less than 30 cm.

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

10. The combined central drainage system for expanding tunnel drainage capacity according to claim 8, characterized in that: The special-shaped concrete backfill ditch (47) blocks the transverse water-guiding blind ditch (51) on both sides of the ditch inspection well (43), and a T-shaped connecting steel pipe (7) is provided in the special-shaped concrete backfill ditch (47), an inlet of the T-shaped connecting steel pipe (7) extends into the transverse water-guiding blind ditch (51) on the upstream side of the ditch inspection well (43), one outlet of the T-shaped connecting steel pipe (7) extends into the transverse water-guiding blind ditch (51) on the downstream side of the ditch inspection well (43), and the other outlet extends into the ditch inspection well (43); A plurality of drainage holes are provided on the side wall of the T-shaped connecting steel pipe (7) extending into the transverse water diversion blind ditch (51), and the T-shaped connecting steel pipe (7) is wrapped with a geotextile.

11. The combined central drainage system for expanding tunnel drainage capacity according to claim 10, characterized in that: The circular pipe section and each section of the ditch body (42) are provided with a corrosion-resistant steel rope (10); The two ends of the corrosion-resistant steel rope (10) arranged in the circular pipe section are correspondingly tied to the external steel components of the side walls of the central groove 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) arranged in the ditch body (42) are correspondingly tied to the side wall external steel components 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).

12. A construction method for a combined central drainage system for expanding tunnel drainage capacity according to claim 11, characterized in that: The construction steps include: Step 1: measuring and laying out the lines, marking the positions of the central ditch inspection well (35), the drainage ditch groove (41) and the ditch inspection well (43) on the surface of the road structure (2); Step 2: Remove the asphalt surface layer (23) directly above and within a 50 cm range around the central ditch inspection well (35), the drainage ditch groove (41) and the water ditch inspection well (43), and cut the concrete road slab (22) directly above and within a 30 cm range around the central ditch inspection well (35), the drainage ditch groove (41) and the water ditch inspection well (43); Step 3: Divide the tunnel (1) into multiple independent construction zones with the central trench inspection well (35) as the dividing line. Then, according to the availability of construction personnel and related machinery and equipment, parallel operations are carried out on multiple non-adjacent construction zones until all the trench bodies (42), concrete backfill trench sides (44) and drainage components (5) are completed. Adjacent construction zones shall not be operated simultaneously. Step 4: construct the ditch inspection well (43) and the special-shaped concrete backfill ditch side (47), and complete the installation of the water pipe B (6) and the T-shaped connecting steel pipe (7) during the construction process; Step 5: After the construction of the new drainage ditches (4) in all construction zones is completed, the construction waste in the new drainage ditches (4) is removed, and the two ends of the corrosion-resistant steel rope (10) are tied to the side wall external steel components of the ditch inspection wells (43) at both ends of the corresponding ditch body (42), and then the prefabricated reinforced concrete cover plate (45), the thickened prefabricated reinforced concrete cover plate (46) and the anti-floating and anti-seepage cover plate (36) are installed; Step 6: Restore the concrete road slab (22) and the asphalt surface layer (23) layer by layer from bottom to top.

13. The construction method of the combined central drainage system for expanding the drainage capacity of a tunnel according to claim 12, characterized in that: The method for operating a single construction zone in step 3 includes the following steps: Step A: Set up construction fences and safety cones at the boundaries of the construction area for safety protection; Step B, open and remove the cover plate of the central trench inspection well (35) at the front and rear ends of the construction partition, and then evenly wrap and stick the water-swellable water stop strip (362) on the side wall of the cover plate to transform it into an anti-floating and anti-seepage cover plate (36); Step C, using the central trench inspection wells (35) at the front and rear ends of the construction zone as working surfaces, dredging the circular pipe trench (32) within the construction zone, and adding a corrosion-resistant steel rope (10) in each circular pipe section, with the two ends of the corrosion-resistant steel rope (10) correspondingly tied to the side wall external steel components of the central trench inspection wells (35) at both ends of the corresponding circular pipe section; Step D, using a flow-line operation method to complete the construction of the ditch body (42), the concrete backfill ditch side (44) and the drainage assembly (5), specifically includes the following steps: Step a, using a mechanical breaker to break up the cut concrete road slab (22), and transporting the concrete fragments out of the tunnel (1); Step b, after the concrete road panel (22) is crushed for 10 meters, the inverted arch backfill layer (21) and the central ditch inspection well (35) within the scope of the drainage ditch (41) to be excavated are partially mechanically chiseled out, and the concrete fragments are transported away from the tunnel (1); The excavation slope of the drainage ditch (41) to be excavated near the existing tunnel center ditch (3) is determined according to the distance between the drainage ditch (41) to be excavated and the circular pipe ditch (32). On the one hand, the distance between the excavation edge of the drainage ditch (41) to be excavated and the circular pipe ditch (32) is required to be no less than 30 cm. On the other hand, the excavation edge of the drainage ditch (41) to be excavated is required to intersect with the blind ditch (33) at the top of the ditch, and the height of the intersection is required to be no less than 20 cm, so as to ensure that the depth of the transverse water diversion blind ditch (51) is no less than 20 cm. Step c: Excavate the working surface of the delayed drainage ditch (41) to 20 meters, and complete the construction of the ditch body (42), concrete backfill ditch side (44) and drainage assembly (5) according to the situation, specifically: If the ditch body (42) is formed by splicing prefabricated ditch body components, the prefabricated ditch body components are hoisted and placed in the drainage ditch groove (41), and then holes are drilled on the side wall of the ditch body (42) away from the existing tunnel center ditch (3), and then the cut transverse drainage pipe (8) is connected to the ditch body (42) by sleeve connection, and the water guide pipe A (52) is installed in the reserved hole on the side wall of the ditch body (42), and then the transverse water guide blind ditch (51) is filled with crushed stone wrapped with geotextile, and the gap between the ditch body (42) and the two side walls of the drainage ditch groove (41) is symmetrically backfilled with concrete to form a concrete backfill ditch side (44); If the ditch body (42) is a concrete cast-in-place structure, the tied ditch body (42) steel bars and the inner mold of the ditch body (42) are first hoisted into the drainage ditch groove (41), and then the gap between the inner mold and the drainage ditch groove (41) is poured with concrete. During the concrete pouring process, the cut transverse drainage pipe (8) is connected to the inner mold by a sleeve connection, and the transverse water diversion blind ditch (51) is filled with crushed stones wrapped with geotextiles, and the installation of the water diversion pipe A (52) is completed at the same time.

14. A method for operating a combined central drainage system for expanding tunnel drainage capacity according to claim 13, characterized in that: The horizontal drainage pipe (8) close to the existing tunnel center ditch (3) drains the groundwater into the existing tunnel center ditch (3), and the horizontal drainage pipe (8) close to the newly built drainage ditch (4) drains the groundwater into the newly built drainage ditch (4); When the water level in the existing tunnel center 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 B (6), the existing tunnel center ditch (3) and the newly built drainage ditch (4) are drained relatively independently; When the drainage capacity of the existing tunnel center ditch (3) is insufficient or partially blocked, the water level in the existing tunnel center ditch (3) rises, and the water in the circular pipe ditch (32) is back-pressed into the blind ditch (33) at the top of the ditch through the drainage hole at the top, and then flows into the newly built drainage ditch (4) through the transverse water guide blind ditch (51) and the water guide pipe A (52), thereby achieving joint drainage of the existing tunnel center ditch (3) and the newly built drainage ditch (4); When the water level in the central ditch inspection well (35) rises due to blockage of the circular pipe ditch (32) or insufficient drainage capacity, the water can also be diverted to the ditch inspection well (43) through the water guide pipe B (6); When the water level in the central trench inspection well (35) rises to the anti-floating and anti-seepage cover plate (36), the water-expanding waterstop strip (362) absorbs water and expands to prevent water from leaking upward to the road surface. Moreover, due to the expansion of the water-expanding waterstop strip (362), the anti-floating and anti-seepage cover plate (36) is tightly fitted to the wellhead of the central trench inspection well (35) to resist the buoyancy of water. When the existing tunnel center ditch (3) or the newly built drainage ditch (4) is blocked, the center ditch inspection well (35) or the 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 perform ditch maintenance work on the existing tunnel center ditch (3) or the newly built drainage ditch (4).

Images