Bridge head middle division zone drainage system and construction method
By designing water collection, diversion, and drainage subsystems in the median strip at the bridgehead, structural defects caused by water accumulation in the median strip at the bridgehead are solved, achieving long-term safety and smooth driving in the bridge transition section. This method is suitable for the construction of highway and first-class highway bridges.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-01-31
- Publication Date
- 2026-03-13
AI Technical Summary
Insufficient drainage capacity in the median strip area at the bridgehead leads to water accumulation, causing structural defects such as roadbed softening, slope erosion, backfill loss, and slab breakage. Conventional maintenance measures only address the symptoms, not the root cause.
Design a water collection subsystem, a diversion subsystem, and a discharge subsystem, including a C25 cast-in-place concrete water collection well, a PE pipe diversion system, and a C25 concrete covered drainage ditch to form an integrated drainage system. Through a comprehensive solution for water collection, diversion, and discharge, combined with construction methods, ensure the system's stability and durability.
This method addresses the problem of water accumulation in the median strip at the bridgehead at its source, prevents secondary damage, improves the structural safety and driving smoothness of the bridge transition section, is easy to construct and maintain, and is suitable for the construction of highway and first-class road bridges.
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Abstract
Description
Technical Field
[0001] This application relates to the field of highway bridge drainage technology, and in particular to a bridge abutment median drainage system and construction method. Background Technology
[0002] In the construction of expressways and first-class highways, the central median strip is a key facility to ensure driving safety. Its raised structure (generally 15-20 cm above the road surface) combined with green vegetation not only achieves physical isolation of oncoming traffic but also provides continuous visual guidance for drivers, significantly improving road traffic efficiency and driving safety.
[0003] In the roadbed section, the median strip, through a comprehensive design of longitudinal and transverse drainage systems, effectively removes rainwater and irrigation water from green areas, preventing water accumulation from damaging the roadbed and surrounding structures. However, the median strip located at the bridge abutment transition section often becomes a drainage bottleneck due to limitations imposed by concrete slabs, guardrails, and insufficient height of the green belt. Especially when the bridge abutment is within the superelevation range, rainwater from the road surface easily accumulates there. Influenced by the longitudinal slope of the bridge and the elevation difference between the roadbed and the subgrade, this area naturally forms a low-lying catchment area. This area often lacks effective drainage facilities, resulting in insufficient actual drainage capacity and long-term accumulation of rainwater and irrigation water from the road surface.
[0004] Such water accumulation problems pose a dual threat: firstly, continuous infiltration softens the roadbed fill, reducing soil strength and affecting roadbed stability; secondly, overflowing water directly erodes the slope protection structure, exacerbating soil erosion. In severe cases, it can also lead to backfill loss, gully expansion, and other problems, resulting in structural defects such as bridge approach slope damage and bottom voids in the approach slabs, threatening the structural safety and ride comfort of the bridge transition section.
[0005] To address the aforementioned problems, conventional treatment methods often involve removing and repairing the slope cones or grouting under the slabs after damage occurs. These measures only temporarily alleviate the surface symptoms and cannot effectively solve the root cause of water accumulation in the central median, making it difficult to prevent recurrence. This "treating the symptoms but not the root cause" maintenance model not only increases maintenance costs and affects driving smoothness but also poses a long-term threat to the structural safety of the bridge transition section.
[0006] Therefore, developing a drainage system and supporting construction methods that can solve the problem of water accumulation in the median strip at bridgeheads from the source, effectively prevent secondary diseases such as roadbed softening and slope erosion, and is structurally durable, easy to construct and maintain, has become an urgent technical problem to be solved in the field of highway bridge construction. Summary of the Invention
[0007] This invention addresses the problems of insufficient drainage capacity in the median strip at bridge abutments, leading to a series of structural defects caused by water accumulation, and the fact that conventional maintenance measures only provide temporary relief. It provides a drainage system and construction method for the median strip at bridge abutments, fundamentally solving the problem of water accumulation in the median strip at the source. This effectively prevents secondary defects such as roadbed softening, slope erosion, backfill loss, and slab detachment, ensuring the long-term structural safety and smooth traffic flow of the bridge transition section. Furthermore, it features structural durability, convenient construction, and easy maintenance.
[0008] The objective of this invention is primarily achieved through the following approach: A median strip drainage system for bridge abutments includes a water collection subsystem, a diversion subsystem, and a discharge subsystem connected in sequence. The water collection subsystem, diversion subsystem, and discharge subsystem work together to collect, divert, and discharge accumulated water in the median strip of the bridge abutment. The specific structure is as follows: The water collection subsystem is a C25 cast-in-place concrete structure water collection well, which is excavated, laid out, and cast into shape in the water collection area of the median strip at the bridge abutment. The top of the water collection well is equipped with an openable cover plate for daily inspection, dredging, and maintenance. The water collection well can realize the functions of centralized collection of water, buffering and energy dissipation, sedimentation and filtration, and preventing siltation. Its size is calculated and determined in combination with the median strip collection area at the bridge abutment, local rainfall intensity, and greening irrigation water consumption to ensure that water can be quickly collected and does not overflow.
[0009] The diversion subsystem is a high-strength PE pipe. The top of the PE pipe is embedded in the cast-in-place sidewall of the sump and fixed with a concrete fixing platform. The bottom of the PE pipe is embedded in the sidewall of the discharge subsystem and simultaneously fixed with a concrete fixing platform. Both ends of the PE pipe are tightly wrapped with a filter geotextile made of high-strength, anti-aging material, which can effectively filter silt and impurities in the water and prevent clogging inside the pipe. The PE pipe is laid out along the slope of the cone and fixed to the surface of the cone slope in front of the platform with steel bars and clamps every 2 meters, forming a stable directional diversion path extending along the slope towards the discharge subsystem. The concrete fixing platform is tightly fitted to the PE pipe, the sidewall of the sump, and the sidewall of the drainage ditch. After casting, it forms an integral structure with the components, which can effectively prevent leakage and erosion damage at the connection.
[0010] The drainage subsystem is a C25 concrete cover drainage ditch installed under the bridge. The drainage ditch receives water from the diversion subsystem and smoothly guides the water to the side ditches of the roadbed on both sides or the municipal drainage network to complete the final discharge of the accumulated water. The cover of the drainage ditch adopts an openable structure design, and the cover and the ditch body are sealed to ensure unobstructed drainage and facilitate subsequent inspection and dredging of the inside of the drainage ditch.
[0011] This invention also discloses a construction method for a median strip drainage system at bridge abutments, used for constructing the aforementioned drainage system, comprising the following steps: Step 1: On-site survey and layout. Based on the alignment, elevation difference, catchment area, and drainage conditions under the bridge, determine the specific locations, dimensions, and directions of the water collection wells, PE diversion pipes, and concrete cover drainage ditches. Use professional surveying equipment such as total stations to accurately lay out and mark the lines, ensuring that the layout accuracy meets the requirements of the construction specifications.
[0012] Step 2: Earthwork excavation. According to the layout marks, excavate the sump pit in the median strip confluence area at the bridge abutment, excavate the PE diversion pipe laying trench on the cone slope, and excavate the drainage ditch pit under the bridge. During the excavation process, strictly control the slope and depth of the pit to prevent the pit from collapsing. The excavation depth is determined in combination with the groundwater level and the installation elevation requirements of each component. If groundwater is encountered after excavation, temporary drainage facilities must be set up to remove the groundwater and avoid water accumulation in the pit, which would affect the construction quality. After the excavation is completed, the bottom of the pit is leveled and compacted to ensure that the bottom of the pit is dense and to provide a stable foundation for the subsequent installation of components.
[0013] Step 3: Construction of the water collection well. C25 concrete is used for in-situ casting. During the pouring process, holes for installing PE guide pipes are reserved to ensure that the position and size of the holes match the PE pipes, avoiding installation difficulties caused by hole deviations. After the concrete is poured, it is cured for no less than 7 days. During the curing process, moisture retention and heat preservation measures are taken to prevent problems such as cracking and insufficient strength of the concrete. After the curing is up to standard, the openable cover is installed to ensure that the cover is firmly installed and can be opened smoothly.
[0014] Step 4: Installation of the diversion subsystem. Cut the high-strength PE pipe to the designed length, ensuring the cut surface is smooth, burr-free, and undamaged. Tightly wrap the filter geotextile around both ends of the PE pipe and secure it firmly to prevent loosening or falling off. Insert the top of the PE pipe into the pre-drilled hole in the sump, adjust it into place, and then fix it with a concrete fixing platform. Lay the bottom of the PE pipe to the pre-set position in the drainage ditch foundation pit, adjusting the PE pipe's direction to match the slope surface, ensuring the pipe slope matches the slope terrain and meets the hydraulic requirements for smooth directional water flow. Fix the PE pipe to the slope surface every 2 meters using steel bars and clamps, ensuring the fixing strength of the steel bars and clamps meets long-term use standards to prevent displacement or loosening of the PE pipe. Finally, use a concrete fixing platform to fix the bottom of the PE pipe to the side wall of the drainage ditch, ensuring a tight connection.
[0015] Step 5: Construction of the discharge subsystem. C25 concrete is used to pour the drainage ditch under the bridge. During the pouring process, ensure a tight connection with the bottom of the PE pipe to avoid gaps that could lead to leakage. Reserve a cover plate installation groove to ensure that the groove size matches the cover plate. After the concrete has cured to the required standard, install the openable cover plate and seal the connection between the cover plate and the ditch body to prevent rainwater from seeping into the outside of the ditch body and affecting the stability of the surrounding soil.
[0016] Step 6: Backfilling and Commissioning. The sump pit, PE pipe laying trench, and drainage ditch pit are backfilled in layers. The backfill soil is well-graded, free of debris. Each layer should not exceed 30cm in thickness, and each layer should be compacted to a compaction degree of at least 95% to ensure the backfill is dense and prevent damage to components due to later settlement. After backfilling, a water storage commissioning is performed. An appropriate amount of clean water is injected into the sump pit to check for leaks at all connections and to ensure smooth drainage. Any leaks or poor drainage are rectified promptly to ensure the system meets drainage requirements.
[0017] Step 7: Finished product maintenance, clean up the construction site, remove construction waste, and restore surrounding vegetation; conduct a comprehensive inspection of all components of the drainage system to ensure that each component is firmly installed and drainage is unobstructed; clarify the cycle and requirements for daily inspection, dredging, and maintenance, regularly dredge the collection well, inspect the PE pipes, and clean the drainage ditch to ensure long-term stable operation of the system.
[0018] In summary, compared with the prior art, the present invention has the following beneficial technical effects: (1) This invention proposes a comprehensive drainage system that integrates “collection-diversion-discharge” and is specifically designed for the special part of the median strip at the bridgehead. It completely solves the problem of water accumulation in the median strip at the bridgehead from the source, and transforms the passive maintenance mode of “treating the symptoms but not the root cause” in the existing technology into an active prevention mode. It effectively prevents the occurrence of secondary diseases such as roadbed softening, slope erosion, backfill soil loss and slab voiding, and significantly improves the structural safety and driving smoothness of the bridge transition section. (2) The water collection subsystem of the present invention adopts C25 cast-in-place concrete water collection well, which has multiple functions such as centralized collection, buffering and energy dissipation, sedimentation and filtration and anti-accumulation and siltation. It can effectively weaken the impact force of high-speed water flow and protect downstream pipelines. At the same time, it can achieve primary purification of accumulated water through sedimentation and filtration, reducing the risk of pipeline siltation. The design of the openable cover plate facilitates daily inspection, silt removal and maintenance, and reduces maintenance costs. (3) The diversion subsystem of the present invention uses high-strength PE pipe, which is resistant to erosion and corrosion and has a long service life; the pipe opening is tightly wrapped with reverse filter geotextile, which effectively filters mud and sand impurities in the water and fundamentally solves the problem of pipe blockage; the PE pipe is sealed to the water collection well and drainage ditch through concrete fixing platform and fixed with steel reinforcement clamps, which ensures the long-term stability of the pipeline, resists natural displacement and aging effects, and effectively prevents leakage and erosion damage at the connection; (4) The discharge subsystem of the present invention adopts C25 concrete cover drainage ditch, which has good structural durability and ensures that the accumulated water can be discharged smoothly and efficiently to the roadbed side ditch or municipal drainage network, avoiding secondary water accumulation under the bridge; the openable cover design takes into account both smooth drainage and convenient daily maintenance. (5) The construction method of the present invention has a standardized process, clear steps, reasonable connection between each link, convenient construction, strong operability, and can adapt to the complex construction environment at the bridgehead; by strictly controlling the quality of key processes such as foundation pit excavation, concrete pouring, component fixing, backfilling and compaction, the construction quality of the drainage system is ensured and the construction cycle is shortened; at the same time, the construction process has little impact on the surrounding environment, which is conducive to environmental protection. (6) The drainage system of the present invention has a reasonable overall structural design, scientific material selection of components, strong durability, low failure rate, simple daily maintenance, and can operate stably for a long time. It is suitable for drainage scenarios in the median strip of various highways and first-class highways, especially suitable for areas with superelevation, large longitudinal slope and differences in elevation between roadbed and bridge, and has broad application prospects and promotion value. Attached Figure Description
[0019] Figure 1 This is a schematic diagram of one structure of the present invention.
[0020] Attached reference numerals: 1-Water collection well, 2-PE pipe, 3-Concrete fixing platform, 4-Reverse filter geotextile, 5-Reinforcing steel bar, 6-Drainage ditch. Detailed Implementation
[0021] The technical solution of the present invention will be further described in detail below through specific embodiments and in conjunction with the accompanying drawings. It should be understood that the implementation of the present invention is not limited to the following embodiments, and any modifications and / or alterations made to the present invention will fall within the protection scope of the present invention.
[0022] like Figure 1 As shown, this invention discloses a technical solution: a median strip drainage system for bridge abutments, applied to the median strip area of a highway bridge abutment. This area is a superelevation section with a large longitudinal slope of the bridge, resulting in a height difference between the roadbed and the bridge, which has long caused water accumulation problems, leading to diseases such as slope erosion and roadbed softening.
[0023] The drainage system comprises a sequentially connected water collection subsystem, a diversion subsystem, and a discharge subsystem: The water collection subsystem consists of C25 cast-in-place concrete collection well 1, based on the catchment area of the region (approximately 80m²). 2 Based on calculations of local rainfall intensity and irrigation water consumption for greening, the dimensions of water collection well 1 are 1.5m long, 1.2m wide, and 1.8m deep. It is excavated, laid out, and cast in the most severely waterlogged area of the median strip at the bridgehead. The top of water collection well 1 is equipped with an openable reinforced concrete cover plate. The size of the cover plate matches the opening of water collection well 1. The opening method is a flip-top type, which is convenient for daily inspection, dredging, and maintenance. The inner wall of water collection well 1 is treated with cement mortar to enhance impermeability and realize the functions of concentrated collection of water, buffering and energy dissipation, sedimentation and filtration, and preventing siltation.
[0024] The diversion subsystem consists of a high-strength PE pipe 2 with a nominal diameter of 500mm. PE pipe 2 is made of HDPE material with a compressive strength of not less than 1.6MPa and anti-aging performance meeting relevant highway engineering standards. The top of PE pipe 2 is embedded in the cast-in-place sidewall of the sump 1 and fixed using a C25 concrete fixing platform 3, with dimensions of 80cm long, 60cm wide, and 1.7m high. The bottom of PE pipe 2 is embedded in the sidewall of the discharge subsystem and also fixed using a C25 concrete fixing platform 3. Both ends of PE pipe 2 are tightly wrapped with high-strength, anti-aging geotextile 4, with a pore size of 0.1-0.2mm. It is securely fixed with stainless steel cable ties to prevent loosening and falling off, and can effectively filter mud and sand impurities in the water; PE pipe 2 is laid out in close contact with the slope surface of the cone, the slope of the cone is 1:1.5, and every 2 meters, Φ16 steel bar 5 and stainless steel clamps are used to fix PE pipe 2 to the surface of the cone slope in front of the platform. The steel bar 5 penetrates into the soil of the cone slope to a depth of not less than 50cm to ensure a firm fixation, forming a stable directional flow path extending along the slope surface and towards the discharge subsystem; the concrete fixing platform 3 is tightly attached to PE pipe 2, the side wall of the water collection well 1, and the side wall of the drainage ditch 6. After being cast, it forms an integral structure with each component, which can effectively prevent leakage and erosion damage at the connection.
[0025] The drainage subsystem consists of a C25 concrete slab drainage ditch 6 installed under the bridge. The drainage ditch 6 has a cross-sectional dimension of 60cm wide and 50cm deep, and adopts a pre-designed hydraulic slope of 0.5% to ensure smooth water flow. The length of the drainage ditch 6 is determined according to the drainage needs under the bridge. One end is sealed to the bottom of the PE pipe 2, and the other end is connected to the roadbed ditch to guide the accumulated water to the roadbed ditch for discharge. The drainage ditch 6 cover is an openable reinforced concrete slab with a thickness of 15cm and a length of 1.0m. The cover is sealed to the ditch body with a rubber sealing strip, which not only ensures unobstructed drainage but also facilitates later inspection and dredging of the drainage ditch 6.
[0026] This embodiment also provides a construction method for the above-mentioned bridge abutment median drainage system, including the following steps: Step 1: On-site survey and layout. Organize professional technicians to conduct a detailed survey of the median strip area at the bridgehead, measure the alignment, elevation difference, catchment area, and drainage conditions under the bridge. Based on the design requirements, determine the specific layout, size, and direction of the water collection well 1, PE diversion pipe, and concrete cover drainage ditch 6. Use a total station to mark the layout. Set up marker stakes around the foundation pits of water collection well 1 and drainage ditch 6, as well as along the laying path of PE pipe 2, to ensure that the layout accuracy error does not exceed 5cm.
[0027] Step 2: Earthwork excavation. Following the marked lines, excavators and manual labor are used for earthwork excavation. A sump pit (1) is excavated in the median strip confluence area at the bridge abutment, with dimensions of 1.7m long, 1.4m wide, and 1.9m deep (with a 10cm backfill layer). A trench for laying PE drainage pipes is excavated on the conical slope, with a width of 60cm and a depth of 50cm. A drainage ditch pit (6) is excavated under the bridge, with dimensions of 70cm wide and 60cm deep (with a 10cm backfill layer). Due to the high groundwater level in this area, temporary drainage ditches (6) and sump pit (1) are set up around the pits during excavation. Pumping equipment is used to remove groundwater and prevent water accumulation in the pits. After excavation, a rammer is used to level and compact the bottom of the pits, ensuring a compaction degree of no less than 95% to guarantee a dense bottom.
[0028] Step 3: Construction of Collection Well 1. C25 concrete will be used for in-situ casting. The concrete mix ratio is cement:sand:gravel:water = 1:1.83:3.47:0.55. Before pouring, check the flatness and compaction of the bottom of the foundation pit. After passing the checks, tie the reinforcing steel bars. 5. Install the formwork. Steel formwork will be used, and it must be firmly installed and tightly sealed. During the pouring process, pre-drill holes for PE guide pipes. The hole diameter is 510mm, located in the middle of the side wall of Collection Well 1, 1.0m from the bottom. Ensure the hole position is correct. The dimensions are matched with PE pipe 2; the concrete is poured in layers, with each layer not exceeding 50cm in thickness, and compacted using an immersion vibrator to avoid quality defects such as honeycomb and pitting; after the concrete is poured, it is covered with geotextile for moist curing, which lasts for 10 days, during which water is sprayed regularly to keep the concrete surface moist; after the curing meets the standard (the concrete strength reaches more than 75% of the design strength), an openable reinforced concrete cover plate is installed to ensure that the cover plate is firmly installed and can be opened smoothly.
[0029] Step 4: Installation of the diversion subsystem. Cut the high-strength HDPE pipe 2 to the designed length (the total length of PE pipe 2 in this case is 8m) using a dedicated cutting machine to ensure a smooth, burr-free, and undamaged cut surface. Tightly wrap the filter geotextile 4 around both ends of the PE pipe 2 and secure it firmly with stainless steel cable ties to prevent loosening and falling off. Insert the top of the PE pipe 2 into the pre-drilled hole in the water collection well 1, adjust the position of the PE pipe 2 to ensure that the center axis of the pipe is aligned with the center of the hole, and use C25 concrete to pour a fixing platform. The fixing platform should fit tightly against the side wall of the water collection well 1 and the PE pipe 2, and then vibrate to compact it. Lay the bottom of the PE pipe 2 to the pre-set position in the drainage ditch 6 foundation pit. The PE pipe 2 is positioned to conform to the slope of the cone, ensuring that the pipe slope matches the slope and meets the hydraulic requirements for smooth directional water flow. Every 2 meters, Φ16 steel bars 5 and stainless steel clamps are used to fix the PE pipe 2 to the surface of the cone slope. The steel bars 5 penetrate 60cm into the soil of the cone slope and are anchored with cement mortar. Rubber pads are placed between the clamps and the PE pipe 2 to prevent damage to the PE pipe 2. Then, a fixing platform is poured with C25 concrete to fix the bottom of the PE pipe 2 to the side wall of the drainage ditch 6. The fixing platform is 70cm long, 50cm wide, and 35cm high. After pouring, it is vibrated to ensure that the connection is tightly sealed and effectively prevents leakage.
[0030] Step 5: Construction of the drainage subsystem. C25 concrete is used to pour drainage ditch 6 under the bridge, with the concrete mix ratio consistent with that of the collection well 1. Before pouring, check the flatness and compaction of the bottom of the drainage ditch 6 foundation pit. After passing the inspection, tie the reinforcing bars 5 and install the formwork. Steel formwork is used, and it is installed firmly and sealed tightly. During the pouring process, ensure a tight connection with the bottom of PE pipe 2. Fill the connection between the bottom of PE pipe 2 and drainage ditch 6 with cement mortar to prevent gaps and leakage. Reserve a cover plate installation groove with a depth of 10cm and a width matching the cover plate. The concrete is poured in layers, with each layer not exceeding 50cm in thickness, and compacted using an immersion vibrator. After the concrete is poured, cover it with geotextile for moisture retention and curing for 8 days. After curing, install the openable reinforced concrete cover plate 5, and install a rubber sealing strip at the connection between the cover plate and the ditch body to seal it and prevent rainwater from seeping into the outside of the ditch body.
[0031] Step 6: Backfilling and Commissioning. The foundation pits for the water collection well 1, PE pipe 2 laying trench, and drainage ditch 6 are backfilled in layers. The backfill soil is well-graded, free of debris; stones, weeds, and other impurities are removed. Each backfill layer is 25cm thick, and each layer is compacted with a rammer to a compaction degree of no less than 95%, ensuring the backfill soil is dense and preventing damage to components due to later settlement. After backfilling, water storage and commissioning are performed. Clean water is injected into the water collection well 1 to 2 / 3 of its depth. Observe for 24 hours, checking for leaks at all connections, smooth drainage from PE pipe 2, and water accumulation in drainage ditch 6. If a slight leak is found at the connection between PE pipe 2 and water collection well 1, it is repaired with cement mortar. After rectification, commissioning is performed again until the system is leak-free and drainage is smooth.
[0032] Step 7: Finished product maintenance. Clean up the construction site, remove construction waste and excess soil, and restore surrounding green vegetation; conduct a comprehensive inspection of all components of the drainage system to ensure that the water collection well 1, PE pipe 2, and drainage ditch 6 are firmly installed, the covers open smoothly, and the drainage system is leak-free and drains smoothly; clarify daily maintenance requirements: inspect water collection well 1 monthly and dredge it quarterly; inspect PE pipe 2 every six months to check for damage, loosening, siltation, etc.; conduct a comprehensive cleaning of drainage ditch 6 annually to ensure smooth drainage; establish a maintenance log to record maintenance status and ensure long-term stable operation of the system.
[0033] After the drainage system in this embodiment was completed and a year of trial operation was conducted, the problem of water accumulation in the median strip at the bridge abutment was completely solved. No problems such as roadbed softening, slope erosion, or loss of backfill soil occurred. The drainage system operated stably, was easy to construct and maintain, and achieved the intended purpose of the invention. It is suitable for promotion and application in similar median strip drainage scenarios at bridge abutments.
[0034] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.
Claims
1. A drainage system for the median strip at a bridge abutment, characterized in that: It includes a water collection subsystem, a diversion subsystem, and a discharge subsystem that are connected in sequence. The water collection subsystem, the diversion subsystem, and the discharge subsystem work together to collect, divert, and discharge the water accumulated in the median strip at the bridgehead. The water collection subsystem is a C25 cast-in-place concrete structure water collection well (1), which is excavated and set in the water collection area of the median strip at the bridgehead. The top of the water collection well (1) is equipped with an openable cover plate. The diversion subsystem is a PE pipe (2). The top of the PE pipe (2) is buried in the cast-in-place concrete fixing platform (3) on the side wall of the water collection well (1). The bottom of the PE pipe (2) is buried in the side wall of the discharge subsystem and is also fixed by the concrete fixing platform (3). The pipe opening of the PE pipe (2) is wrapped with reverse filter geotextile (4). The PE pipe (2) is in contact with the slope surface of the cone. Every 2-3 meters, steel bars (5) and clamps are used to fix it to the surface of the cone slope in front of the platform. The discharge subsystem is a C25 concrete slab drainage ditch (6) installed under the bridge. The drainage ditch (6) receives water from the diversion subsystem and smoothly guides it to the side ditches of the roadbed on both sides or the municipal drainage network to complete the final discharge of the accumulated water.
2. A construction method for a median strip drainage system at bridge abutments, characterized in that, The construction of the drainage system described in claim 1 includes the following specific steps: Step 1: On-site survey and layout. Based on the alignment, elevation difference, catchment area and drainage conditions of the median strip at the bridgehead, determine the specific layout, size and direction of the water collection well (1), PE diversion pipe and concrete cover drainage ditch (6). Use total station measuring equipment to accurately lay out and mark the lines to ensure that the layout accuracy meets the requirements of the construction specifications. Step 2: Earthwork excavation. According to the layout marks, excavate the water collection well (1) foundation pit in the confluence area of the median strip at the bridgehead, excavate the PE diversion pipe laying trench on the cone slope, and excavate the drainage ditch (6) foundation pit under the bridge. During the excavation process, strictly control the slope and depth of the foundation pit to prevent the foundation pit from collapsing. After the excavation is completed, level and compact the bottom of the foundation pit to ensure that the bottom of the foundation pit is dense. Step 3: Construction of water collection well (1) is carried out by casting C25 concrete in place. During the pouring process, the installation hole of PE guide pipe is reserved to ensure that the hole position and size match the PE pipe (2). After the concrete is poured, it is cured. After the curing meets the standard, the openable cover is installed. Step 4: Installation of the diversion subsystem. Cut the high-strength PE pipe (2) to the designed length, ensuring that the cut surface is flat, smooth, burr-free, and undamaged. Tightly wrap the filter geotextile (4) at both ends of the PE pipe (2) and fix it firmly to prevent loosening and falling off. Insert the top of the PE pipe (2) into the reserved hole of the water collection well (1), and after adjusting it to the position, use a concrete fixing platform (3) to pour and fix it. Lay the bottom of the PE pipe (2) to the preset position of the drainage ditch (6) foundation pit, adjust the direction of the PE pipe (2) to fit the slope surface of the cone, and use steel bars (5) and clamps to fix the PE pipe (2) to the surface of the cone every 2 meters. Then use a concrete fixing platform (3) to pour and fix the bottom of the PE pipe (2) to the side wall of the drainage ditch (6) to ensure a tight connection. Step 5: Construction of the discharge subsystem. C25 concrete is used to pour the drainage ditch (6) under the bridge. During the pouring process, ensure that it is tightly connected to the bottom of the PE pipe (2). Reserve a cover plate installation groove. After the concrete is cured to the standard, install the openable cover plate and seal the connection between the cover plate and the ditch. Step 6: Backfilling and debugging. Backfill the foundation pit of the water collection well (1), the trench for laying PE pipe (2) and the foundation pit of drainage ditch (6) in layers to ensure that the backfill soil is compacted to the standard and to avoid damage to the components due to settlement in the later stage. After the backfilling is completed, water storage debugging is carried out to check whether there is leakage at each connection part and whether the drainage is smooth. Any problems found should be rectified in a timely manner. Step 7: Finished product maintenance. Clean up the construction site, conduct a comprehensive inspection of all components of the drainage system, clarify the cycle and requirements for daily inspection, dredging and maintenance, and ensure the long-term stable operation of the system.
3. The construction method according to claim 2, characterized in that: In step 2, the excavation depth of the foundation pit is determined in conjunction with the groundwater level and the installation elevation requirements of each component. If groundwater is encountered after excavation, temporary drainage facilities need to be set up to remove the groundwater and avoid water accumulation in the foundation pit from affecting the construction quality.
4. The construction method according to claim 2, characterized in that: In steps 3 and 5, after the C25 concrete is poured, the curing time shall not be less than 7 days. During the curing process, appropriate moisturizing and heat preservation measures shall be taken according to the ambient temperature of the construction environment to prevent quality problems such as cracks and insufficient strength of the concrete.
5. The construction method according to claim 2, characterized in that: In step 4, when fixing the PE pipe (2), ensure that the pipe slope is compatible with the terrain of the cone slope and meets the hydraulic requirements for smooth water flow. The fixing strength of the steel bar (5) and the clamp meets the long-term use standard to prevent the PE pipe (2) from shifting or loosening.
6. The construction method according to claim 2, characterized in that: In step 6, the backfill soil is well-graded and free of debris. The backfill thickness in layers does not exceed 30cm. Each layer is compacted after backfilling, with a compaction degree of not less than 95%, to ensure that the backfill soil is dense and to avoid damage to the components due to later settlement.