Construction method for active ice flow dredging under high-cold roadbed

Abstract

The present application relates to the technical field of road engineering, and particularly relates to a high-cold roadbed meltwater underground active dredging construction method, which comprises the following steps: collecting data and conducting site reconnaissance, and analyzing water properties and estimating meltwater volume, and then conducting special planning on the drainage system; conducting measurement and setting out, setting out the seepage ditch axis and the excavation boundary line according to the design coordinates, setting control piles and marking the excavation depth and the base elevation; seepage ditch excavation; base treatment to ensure the base solidity; seepage ditch bottom cast-in-situ concrete construction; inspection well construction; processing a plurality of seepage holes on one side of the top surface of the PE 200mm double-wall corrugated pipe, and then laying the pipe into the seepage ditch; conducting layered backfilling on the seepage ditch; cover plate side ditch construction; seepage ditch outlet setting; system joint debugging and acceptance. The method can actively dredge and drain underground water, and control underwater seepage from the source.

Description

Technical Field

[0001] This invention relates to the field of road engineering technology, and in particular to an active underground drainage method for ice flow in high-altitude and cold-weather roadbeds. Background Technology

[0002] Highway icing is a unique engineering geological phenomenon in high-altitude, frigid regions. Under extremely cold weather conditions, some groundwater or surface water overflows onto the road surface or existing ice, accumulating and freezing layer by layer from bottom to top to form icing. Icing can cause road surface uplift, settlement, slope collapse, landslides, spalling, and roadbed instability, seriously threatening the construction and operation safety of highways in high-altitude, frigid regions. High-altitude, frigid regions receive abundant rainfall in summer and are often water-conserving areas. Excavation work during road construction can easily alter the original hydrogeological conditions, disrupt the groundwater balance, and induce or exacerbate icing disasters.

[0003] Traditional prevention and control methods mainly adopt a passive approach of "interception and accumulation," which involves setting up retaining walls, drainage ditches, and other facilities on both sides of the roadbed in an attempt to intercept and accumulate the moisture generated by the ice flow.

[0004] However, this approach cannot fundamentally solve the water source problem. Instead, the long-term retention of water leads to further frost heave of the roadbed, creating a vicious cycle. Therefore, exploring a prevention and control technology that can actively guide and drain groundwater and control water infiltration at its source has become an urgent need for highway construction in high-altitude and cold regions. Summary of the Invention

[0005] The purpose of this invention is to provide a construction method for actively diverting groundwater in cold-weather roadbeds, which can actively divert and drain groundwater and control water infiltration at the source.

[0006] To achieve the above objectives, the present invention provides a method for active underground drainage of ice flow in high-altitude and cold-weather roadbeds, comprising the following steps:

[0007] Complete data collection and site survey, conduct water property analysis and meltwater volume estimation, and then carry out special planning for the drainage system;

[0008] Conduct surveying and setting out, mark the axis of the seepage ditch and the excavation boundary line according to the design coordinates, set control stakes and mark the excavation depth and base elevation;

[0009] Excavation of seepage trenches;

[0010] Substrate treatment to ensure a solid base;

[0011] Construction of cast-in-place concrete at the bottom of the seepage trench;

[0012] Inspection well construction;

[0013] Several seepage holes are machined on one side of the top surface of the PE200mm double-wall corrugated pipe before it is laid into the seepage trench.

[0014] The seepage trenches were backfilled in layers;

[0015] Construction of covered ditch;

[0016] Installation of seepage trench outlets;

[0017] System integration and acceptance.

[0018] Among the steps of surveying and setting out, marking the seepage ditch axis and excavation boundary line according to the design coordinates, setting control stakes and marking the excavation depth and foundation elevation:

[0019] Using surveying instruments, the axis of the seepage ditch and the excavation boundary line are laid out according to the design coordinates. Control stakes are set every 5m to mark the excavation depth and the elevation of the concrete foundation base. The longitudinal main pipe is set on one side of the mountain or the side of the water direction. The longitudinal slope is set at 3% according to the route design, and the transverse pipe is set at 3%. Suitable drainage points and crossing structures are selected for setting.

[0020] Among the steps involved in excavating the seepage trench:

[0021] The excavation depth is 3 meters, and the excavator is used for layered slope excavation to avoid over-excavation; the base is cleaned manually.

[0022] Among the steps in substrate treatment to ensure the substrate is solid:

[0023] After the seepage trench is excavated, the base is compacted using a wheeled excavator with a hydraulic plate compactor; if the base is soft soil, it is replaced with 30cm thick gravel and compacted to the design requirements.

[0024] Among the steps involved in the construction of cast-in-place concrete at the bottom of the seepage trench:

[0025] For template installation, wooden or steel templates are used, the inside is coated with release agent and fixed, and sponge strips are pasted at the template joints to prevent grout leakage.

[0026] Concrete pouring is carried out using tanker trucks for transportation and manual vibration, following the principle of pouring in layers from low to high, and the surface is then smoothed.

[0027] Among the steps in the construction of inspection wells:

[0028] Based on the longitudinal pipe diameter and for ease of daily inspection and maintenance, the inspection well is set to a diameter of 1 meter and a height of 3 meters. The pipe section adopts C30 reinforced concrete precast pipe body with internal steel ladder. During prefabrication, drainage pipe holes are reserved according to the longitudinal and transverse PE 200mm corrugated pipe positions. After installation, an 8cm polyurethane insulation board is installed 1 meter below the pipe section at the inspection well opening to isolate cold air in winter.

[0029] In the step of machining several seepage holes on one side of the top surface of a PE200mm double-wall corrugated pipe and then laying it into the seepage trench:

[0030] A seepage hole is processed on one side of the top surface of the PE200mm double-wall corrugated pipe. The diameter of the seepage hole is 2cm and the spacing is controlled at 5-10cm to form a semi-arc permeable pipe.

[0031] For pipeline laying, perforated corrugated pipes are installed according to the planned slope with the perforated side facing upwards. The bottom of the pipe is partially enclosed with concrete. Pipe section connections use socket joints, and the joints are sealed with rubber sealing rings and tightly wrapped with permeable geotextile.

[0032] The perforated corrugated pipe is wrapped with permeable geotextile to ensure complete coverage of the perforated area.

[0033] In the step of backfilling the seepage trench in layers:

[0034] Medium-coarse sand was used to backfill the sides of the pipeline, symmetrically from both sides of the pipeline, and compacted with a plate vibrator until it was flush with the top surface of the concrete foundation.

[0035] A second layer of geotextile is laid, and the permeable geotextile is fully covered with a medium-coarse sand layer, with the edges wrapped up to the top of the seepage ditch.

[0036] For gravel filling, clean 30-50mm gravel is filled in layers, each layer is 30cm, and compacted using a hydraulic plate rammer with an excavator. A 20cm space is left on the top surface.

[0037] For the top sealing and roadbed backfilling, coarse sand is used for the top sealing, followed by a 20cm thick layer of medium-coarse sand, and the surface is leveled and compacted.

[0038] Geogrid laying: The geogrid is fully laid along the longitudinal direction of the seepage ditch, with a width of 4m, and is compacted together with the subgrade fill.

[0039] Among the steps in the construction of the cover ditch:

[0040] A precast concrete side ditch with a cover plate is set on one side of the road cut section. The side ditch is arranged with a width of 80cm and a height of 80cm. The top elevation of the side ditch cover plate is controlled to connect smoothly with the cross slope of the hard shoulder, so as to facilitate smooth and unobstructed road surface drainage.

[0041] Among the steps involved in setting up the seepage trench outlet:

[0042] According to the longitudinal and transverse seepage trenches arranged in a comb pattern, and based on their longitudinal slope and the characteristics of the site, the drainage should be directed to a location 10-20 meters away from the route. Inspection wells should be set at the nodes, and 3-5 drainage pipes should be installed at the same time. The drainage pipes should be permeable pipes with open sections. The drainage pipes should be covered with an insulation layer around them and topped with backfilled rubble stones to ensure that the backfill of the drainage pipes is more than 3 meters deep.

[0043] This invention discloses a method for actively diverting groundwater through seepage in high-altitude, cold-weather roadbeds, comprising the following steps: completing data collection and site reconnaissance, conducting water property analysis and meltwater volume estimation, and then carrying out specialized planning for the drainage system; conducting surveying and setting out, marking the seepage ditch axis and excavation boundary line according to the design coordinates, setting control stakes and marking the excavation depth and base elevation; excavating the seepage ditch; treating the base to ensure its solidity; constructing cast-in-place concrete at the bottom of the seepage ditch; constructing inspection wells; processing several seepage holes on one side of the top surface of a 200mm double-wall corrugated PE pipe and then laying it into the seepage ditch; backfilling the seepage ditch in layers; constructing the cover ditch; setting the seepage ditch outlet; and system commissioning and acceptance. This method can actively divert and drain groundwater, controlling water infiltration at its source. Attached Figure Description

[0044] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below.

[0045] Figure 1 This is a flowchart of the active underground dredging construction method for ice flow in high-altitude and cold-weather roadbeds according to the present invention.

[0046] Figure 2 This is a flowchart of step S5 of the present invention.

[0047] Figure 3 This is a flowchart of step S7 of the present invention.

[0048] Figure 4 This is a flowchart of step S8 of the present invention.

[0049] Figure 5 This is a schematic diagram of the longitudinal and transverse guide pipe layout of the present invention.

[0050] Figure 6 This is a standard cross-sectional view of the seepage trench of the present invention.

[0051] Figure 7 This is a standard cross-sectional view of the seepage trench of the present invention.

[0052] Figure 8 This is a cross-sectional layout diagram of the inspection well of the present invention.

[0053] Figure 9 This is a schematic diagram of the deployment of the seepage trench outlet of the present invention.

[0054] Figure 10 This is a schematic diagram of the deployment of the seepage trench outlet of the present invention.

[0055] Figure 11 This is a schematic diagram of the construction site for the seepage trench pipe.

[0056] Figure 12 This is a schematic diagram of the manhole installation and backfilling site.

[0057] Figure 13 This is a schematic diagram of the pebble layer backfill site.

[0058] Figure 14 This is a schematic diagram of the top-level backfill site.

[0059] Figure 15 This is a construction diagram of the outlet of the seepage trench pipe.

[0060] Figure 16 This is a schematic diagram of the stone masonry at the outlet of the seepage trench conduit.

[0061] Figure 17 This is a schematic diagram of the construction of precast cover slab side ditches and the drainage of underground water through infiltration ditches. Detailed Implementation

[0062] Please see Figures 1-17 ,in, Figure 1 This is a flowchart of the active underground dredging construction method for ice flow in high-altitude and cold-weather roadbeds according to the present invention. Figure 2 This is a flowchart of step S5 of the present invention. Figure 3 This is a flowchart of step S7 of the present invention. Figure 4 This is a flowchart of step S8 of the present invention. Figure 5 This is a schematic diagram of the longitudinal and transverse guide pipe layout of the present invention. Figure 6 This is a standard cross-sectional view of the seepage trench of the present invention. Figure 7 This is a standard cross-sectional view of the seepage trench of the present invention. Figure 8 This is a cross-sectional layout diagram of the inspection well of the present invention. Figure 9 This is a schematic diagram of the deployment of the seepage trench outlet of the present invention. Figure 10 This is a schematic diagram of the deployment of the seepage trench outlet of the present invention. Figure 11 This is a schematic diagram of the construction site for the seepage trench pipe. Figure 12 This is a schematic diagram of the manhole installation and backfilling site. Figure 13 This is a schematic diagram of the pebble layer backfill site. Figure 14 This is a schematic diagram of the top-level backfill site. Figure 15 This is a construction diagram of the outlet of the seepage trench pipe. Figure 16 This is a schematic diagram of the stone masonry at the outlet of the seepage trench conduit. Figure 17 This is a schematic diagram of the construction of precast cover slab side ditches and the drainage of underground water through infiltration ditches.

[0063] This invention provides a method for active underground drainage of ice flow in high-altitude and cold-weather roadbeds:

[0064] S1: Complete data collection and site survey, conduct water property analysis and meltwater volume estimation, and then carry out special planning for the drainage system;

[0065] The specific process is as follows:

[0066] Data collection and on-site reconnaissance: Detailed study of the route geological survey report, meteorological data (with a focus on historical maximum frost depth and freeze-thaw cycles), and existing water system maps. Conduct on-site reconnaissance to identify all potential water points (springs, seeping slopes, snowmelt areas), existing ice remnants, and topographic features.

[0067] Water property analysis and meltwater volume estimation: Identify water types (surface runoff, perched water, bedrock fissure water, etc.), and estimate the possible runoff volume in different seasons (especially the spring melt season) by combining hydrogeological parameters and meteorological data.

[0068] Specialized planning for the drainage system: Based on water analysis, meltwater estimation, and route longitudinal slope, a systematic plan for the underground drainage network is developed. The location, burial depth (must be below the maximum frost depth), and longitudinal slope (considering the route longitudinal slope, ensuring ≥1%) of the main longitudinal seepage ditches are determined. The spacing between transverse connecting seepage ditches and inspection wells is planned (typically 30-40 meters per location), and reasonable drainage outlet locations are selected.

[0069] S2: Conduct surveying and setting out, mark the seepage ditch axis and excavation boundary line according to the design coordinates, set control stakes and mark the excavation depth and base elevation;

[0070] The specific process is as follows: Using surveying instruments, the axis of the seepage trench and the excavation boundary line are laid out according to the design coordinates. Control stakes are set every 5 meters to mark the excavation depth and the elevation of the concrete foundation base. The longitudinal main pipe is set on one side of the mountain or the side facing the watercourse. The longitudinal slope is set at 3% (>1%) according to the route design, and the transverse ducts are arranged and measured at 3%. Suitable drainage locations and crossing structures are selected for installation. The longitudinal main pipe is laid along the roadbed longitudinally and connects with each transverse duct. Its core function is to collect the water flow transported by the transverse ducts, forming a complete drainage channel, and ultimately guiding the water to the outside of the roadbed in an orderly manner, ensuring the stability of the roadbed. The longitudinal duct is the main channel of the underground drainage system. The 3% refers to the hydraulic gradient, meaning that the pipe elevation drops by 3 meters for every 100 meters of horizontal distance.

[0071] S3: Excavation of seepage trenches;

[0072] The specific process is as follows: the excavation depth is 3 meters, and the excavator is used to excavate in layers with slope to avoid over-excavation; the base is cleaned manually.

[0073] S4: Base treatment to ensure a solid base;

[0074] The specific process is as follows: After the seepage ditch is excavated, the base is compacted using a wheeled excavator and a hydraulic plate compactor; if the base is soft soil, it is replaced with 30cm thick gravel and compacted to the design requirements.

[0075] S5: Construction of cast-in-place concrete at the bottom of the seepage trench;

[0076] The specific process is as follows:

[0077] S501: Template installation, using wooden or steel templates, applying release agent to the inside and fixing them, and pasting sponge strips at the template joints to prevent grout leakage;

[0078] S502: Concrete pouring, using tanker truck transportation and manual vibration, following the principle of pouring in layers from low to high, with the surface finished.

[0079] S6: Inspection well construction;

[0080] Based on the longitudinal pipe diameter and ease of daily inspection and maintenance, the inspection well is designed with a diameter of 1 meter and a height of 3 meters. The pipe sections are precast C30 reinforced concrete pipes with internal steel ladders. During precasting, drainage pipe holes are pre-reserved according to the positions of the longitudinal and transverse PE 200mm corrugated pipes. After installation, an 8cm polyurethane insulation board is installed 1 meter below the inspection well opening to isolate cold air in winter. Here, the longitudinal pipe refers to the longitudinal main pipe section, which is a segment of the precast C30 reinforced concrete well shaft (each section's height is set according to the total well height of 3 meters), assembled to form a complete inspection well. The reserved drainage pipe holes include reserved longitudinal main pipe holes and transverse guide pipe holes. Longitudinal main pipe holes: used to insert the longitudinal main pipe, ensuring a smooth axis and sealed joints when it passes through the well body. Transverse guide pipe holes: used to connect the transverse drainage auxiliary pipes (also φ200mm HDPE pipes), allowing groundwater to flow into the longitudinal main pipe.

[0081] S7: Process several seepage holes on one side of the top surface of the PE200mm double-wall corrugated pipe, and then lay it into the seepage trench;

[0082] The specific process is as follows:

[0083] S701: Process seepage holes on one side of the top surface of a PE200mm double-wall corrugated pipe. The diameter of the seepage holes is 2cm and the spacing is controlled at 5-10cm to form a semi-arc permeable pipe.

[0084] S702: Pipeline laying: Install perforated corrugated pipes according to the planned slope, with the perforated side facing upwards. The bottom of the pipe is partially enclosed with concrete. Pipe section connections use socket joints. The joints are sealed with rubber sealing rings and wrapped tightly with permeable geotextile.

[0085] S703: Geotextile wrapping: The perforated corrugated pipe is wrapped with permeable geotextile to ensure complete coverage of the perforation area.

[0086] S8: Backfill the seepage trench in layers;

[0087] The specific process is as follows:

[0088] S801: Medium-coarse sand is used to backfill both sides of the pipeline. The backfilling is carried out symmetrically from both sides of the pipeline and compacted with a plate vibrator until it is flush with the top surface of the concrete foundation.

[0089] S802: Secondary laying of geotextile, full-coverage of medium-coarse sand layer with permeable geotextile, and edge wrapping to the top of the seepage trench;

[0090] S803: Gravel filling, layered filling with cleaned 30-50mm pebbles, each layer 30cm, compacted with a hydraulic plate compactor using an excavator, with a 20cm space reserved on the top surface;

[0091] S804: Top sealing and roadbed backfilling, using coarse sand to seal the top, filling with 20cm thick medium-coarse sand, and compacting the surface after leveling;

[0092] S805: Geogrid laying: The geogrid is fully laid along the longitudinal direction of the seepage ditch, with a width of 4m, and is compacted together with the subgrade fill.

[0093] S9: Construction of cover plate side ditch;

[0094] The specific process is as follows:

[0095] A precast concrete side ditch with a cover plate is set on one side of the road cut section. The side ditch is arranged with a width of 80cm and a height of 80cm. The top elevation of the side ditch cover plate is controlled to connect smoothly with the cross slope of the hard shoulder, so as to facilitate smooth and unobstructed road surface drainage.

[0096] S10: Installation of seepage trench outlet;

[0097] The specific process is as follows:

[0098] Based on the longitudinal and transverse seepage trenches arranged in a comb-like pattern, and according to their longitudinal slope and the characteristics of the site terrain, drainage is directed to a location 10-20 meters away from the main drainage route. Inspection wells are installed at the nodes, and 3-5 perforated drainage pipes are simultaneously installed. These perforated pipes are fully perforated and covered with insulation around and on top of the pipes, then backfilled with rubble and stacked, ensuring the backfill depth of the drainage pipes is greater than 3 meters. Here, "according to their longitudinal slope" essentially uses a standardized slope (3%) as the benchmark for the drainage system layout.

[0099] S11: System integration and acceptance.

[0100] The specific process is as follows:

[0101] For the completed infiltration trench section (between the starting inspection well and the ending outlet), water was injected from the upstream inspection well or the pebble drainage layer, and the rise in water level in the downstream inspection well and the water discharge from the permeable pipe were observed. The injection volume and the water discharge response time were recorded to evaluate the collection and longitudinal conduction efficiency of the infiltration trench. Through linkage testing, the entire system demonstrated continuous and smooth drainage during the test, with no prolonged water accumulation, overflow, or backflow in any part. The drainage path was clear and consistent with the process intent.

[0102] This embodiment describes an active underground drainage method for ice spillage on high-altitude and cold-climate roadbeds. Based on the principles of "dredging, drainage, interception, and guidance," it innovatively proposes a combined prevention and control system that addresses the two core aspects of ice spillage formation: "surface water infiltration" and "meltwater overflow from the frozen layer." This system combines "surface water sealing with a concrete slab ditch and active drainage of deep water through a seepage ditch system." The upper concrete slab ditch effectively blocks the surface water infiltration path, while the lower longitudinal and transverse seepage ditch network (containing permeable pipes and graded pebbles) actively collects and drains meltwater from the frozen layer, achieving an active treatment effect of "sealing above and draining below, water flowing away and ice melting."

[0103] This method addresses the unique engineering environment of high-altitude and frigid regions characterized by low temperatures, hypoxia, intense freeze-thaw cycles, and frequent ice runoff. It centers on "active drainage combined with prevention and control," constructing a three-dimensional prevention and control system that integrates surface sealing of covered ditches with underground drainage through infiltration trenches. Its main features are as follows:

[0104] The prevention and control concept has shifted from passive to proactive: abandoning the traditional passive approach of "interception and accumulation," the proactive drainage mechanism of "sealing above and draining below" blocks the infiltration of surface water at the source and systematically dredges the meltwater in the frozen layer, achieving both symptomatic and radical treatment of the runoff ice water.

[0105] The system is scientifically designed to achieve three-dimensional prevention and control: It is the first to create a combined drainage system with the functions of "covered side ditch + seepage ditch", which actively collects and guides groundwater to be discharged horizontally, forming a three-dimensional prevention and control network of "vertical isolation and horizontal diversion".

[0106] The materials and processes are highly targeted, resulting in outstanding durability: all materials and structures are specifically designed for freeze-thaw environments. The seepage trenches are filled with pebbles (mud content ≤3%) to ensure long-term permeability; flexible seals are used at structural joints to accommodate frost heave deformation. The overall system is freeze-thaw resistant, anti-aging, and has a long service life.

[0107] This method is applicable to high-altitude and cold regions with an elevation of 2000–5000m and a freezing depth ≥1.5m. It is mainly used to prevent ice reflux caused by groundwater inrush or groundwater runoff alteration due to excavation construction (road cuts and semi-fill / semi-cut sections). Through an "upper sealing and lower drainage" system, it effectively intercepts surface water and actively drains meltwater from the frozen layer.

[0108] The core principle of this method is based on an in-depth analysis of the formation mechanism of ice runoff disease, namely the vicious cycle of "water replenishment" and "freezing and drainage." Essentially, it is the result of multi-field coupling of water, heat, and force: In winter, as temperatures drop, the surface freezes from top to bottom, forming a relatively impermeable layer. Below this, the unfrozen aquifer expands due to water phase change and the cross-sectional area decreases, leading to a significant increase in pore water pressure. Ultimately, this pressure overflows at weak points in the roadbed and freezes layer by layer into ice. To fundamentally break this cycle, this method establishes the principle of "source control as the primary approach, combined with drainage," and constructs a two-layer prevention and control system of "rigid surface sealing and active underground drainage."

[0109] Upper sealing – rigid barrier, cutting off vertical supply: C30 precast concrete slab side ditches are set up on the outer side of the roadbed. This structure forms a continuous rigid barrier, effectively intercepting and quickly draining surface runoff and snowmelt, physically blocking the channels for their infiltration to the freezing front, and eliminating the possibility of surface water participating in the freeze-heave cycle from the source.

[0110] Downward drainage – actively guides and releases pore water pressure: a mesh drainage system consisting of “longitudinal main seepage trenches + transverse connecting seepage trenches” is laid below the freezing depth.

[0111] Collection and diversion: The infiltration trench is filled with pebbles (mud content ≤3%) to form a highly efficient reverse filter permeable layer, which actively collects and diverts water from the frozen layer and bedrock fissures within the roadbed area.

[0112] Pressure release and directional drainage: A φ200mm HDPE permeable pipe (open area ≥15%) is laid at the bottom of the infiltration trench to provide a low-pressure drainage channel for the accumulated pore water, and to orderly guide harmful groundwater to natural gullies or designated drainage areas outside the roadbed area, thereby eliminating the internal driving force for groundwater to overflow and freeze.

[0113] Collaborative maintenance ensures long-term effectiveness: Through openable covers and inspection wells spaced 30 meters apart, the system enables full-cycle visual monitoring and convenient maintenance of drainage channels, ensuring the continuous and reliable function of the prevention and control system under long-term freeze-thaw cycles.

[0114] Table 1. Relevant data for the project area.

[0115] Table 2 Required Materials List

[0116] Table 3 Required Mechanical Gauges

[0117] Table 4 Required Labor Force

[0118] Quality control measures

[0119] To ensure the effectiveness and long-term durability of the "active underground drainage of ice flow in high-altitude and cold-weather roadbeds" method, a refined quality control system should be established throughout the entire process of investigation, construction, and acceptance. Specific measures are as follows:

[0120] Construction preparation stage control

[0121] (1) Before construction, it is necessary to verify whether the location of the seepage ditch matches the actual water point (spring, seepage surface), the maximum frost depth line and the longitudinal slope of the route, based on the geological survey report and on-site reconnaissance, and to estimate and verify the water catchment volume on-site.

[0122] (2) Raw Material Access and Control Points: All incoming materials must meet the requirements of high-altitude freeze-thaw environments. Gravel and medium-coarse sand: Each 500m³ constitutes an inspection batch. On-site sieving and gradation testing are conducted, and the mud content (≤3%) is strictly controlled. Weathered gravel is strictly prohibited. HDPE permeable pipes: Check the factory certificate of conformity, ring stiffness (≥SN8), and porosity (20%). Randomly cut pipe sections on-site for drop hammer impact testing. Geotextile: Verify its unit area mass (≥250g / ㎡), vertical permeability coefficient, and frost crack resistance.

[0123] Key process control during construction

[0124] (1) Excavation and foundation quality control: Ensure accurate excavation cross-section and solid foundation. Use surveying instruments to monitor the excavation edge line, depth, and slope throughout the process. Foundation acceptance is conducted using light dynamic penetration testing or compaction monitoring. Over-excavation is strictly prohibited. After replacement of weak foundation, the compaction degree must be ≥93%.

[0125] (2) Special control of pipeline installation and sealing: Ensure accurate slope of permeable pipe and absolute sealing of connection. During installation, measure the bottom elevation of the pipe with a level every 5 meters. Before backfilling, conduct water flow test in sections to find any leaks and make timely repairs. Slope deviation ≤ ±0.2%, and keep video records.

[0126] (3) Quality control of filter layer and backfill: Ensure clear gradation of filter layer and compacted backfill to prevent fine soil intrusion and blockage. Layer thickness and materials: On-site measurement and inspection of the thickness of medium and coarse sand layer, geotextile layer and gravel layer. Allowable deviation of each layer thickness ±2cm. Gravel layer compaction degree ≥95%. Geotextile laying must be flat and undamaged, with an overlap width ≥20cm.

[0127] System functional acceptance control

[0128] Control Point: To ultimately verify the overall effectiveness of the "top sealing and bottom drainage" system. Test Method: Following the procedures specified in the "System Linkage Debugging" section of this method, a full-system simulated water flow test was conducted. Groundwater was able to quickly collect through the infiltration ditch system and drain smoothly from the outlet, with no water accumulation, siltation, or backflow within the system. The debugging report contained detailed data, and the conclusion was satisfactory.

[0129] Safety measures

[0130] Safety Management System and Specific Measures

[0131] Organizational structure and education briefing

[0132] Organizational safeguards: A safety production leading group was established, with the project manager as the primary person in charge, and full-time safety officers and on-site technicians serving as part-time safety personnel under the group, forming a grid-based management system.

[0133] Education and Responsibility: Before entering the site, all personnel will receive three levels of safety training, with a focus on working in cold environments, risks associated with special processes, and emergency response. Safety responsibility agreements will be signed with all employees, clearly defining their safety responsibilities.

[0134] Safety measures for special high-altitude environments

[0135] Personnel Health and Protection: Establish a high-altitude health screening and dynamic monitoring system, and equip personnel with cold-weather clothing, goggles, portable oxygen cylinders, and sun protection products. Set up on-site emergency medical points and develop and practice emergency plans for altitude sickness, frostbite, etc.

[0136] Equipment safety: Select specialized equipment adapted to high-altitude, low-pressure environments. Strictly implement winter maintenance, use diesel fuel of -35# or higher and antifreeze, and enforce the winter shutdown procedure of "draining water, labeling, and storing" to prevent equipment from freezing and starting risks.

[0137] Safety control of key processes

[0138] Excavation and slope stabilization: Strictly adhere to the procedure of "excavating one section, supporting one section, and backfilling one section," and strictly prohibit over-excavation and undercutting. Implement a combination of automated monitoring and manual inspection of the road cut slopes (no less than twice daily). If any exceedances are detected, immediately halt work, evacuate personnel, and implement counter-pressure measures.

[0139] Confined space operations: Before entering inspection wells, deep ditches, etc., it is essential to strictly implement the requirement of having a dedicated person continuously monitor the area and equipping it with emergency rescue equipment.

[0140] Construction traffic safety: Strict adherence to safety operating procedures is required throughout the construction process. The work control area must be properly designated with warning zones (≥1000m), transition zones, buffer zones, work areas, and termination zones, and must be equipped with complete and conspicuous safety signs, traffic barriers, and nighttime warning lights. All construction personnel must wear reflective vests, and construction vehicles must travel along designated routes to ensure effective separation between the work area and traffic lanes.

[0141] Seasonal and Specialized Safety Risk Prevention and Control

[0142] Anti-slip and fall prevention: In icy and snowy weather, promptly remove accumulated ice and snow from work surfaces, passageways, and ladders, and install anti-slip facilities. Sturdy guardrails and safety nets must be installed for work near edges and in ditches.

[0143] Electricity and Fire Prevention: In high-altitude and cold regions, power lines should be laid in accordance with regulations, and antifreeze and explosion-proof electrical equipment should be used. Unauthorized wiring and connections are strictly prohibited. Sufficient fire-fighting equipment should be provided in living areas and oil and material storage areas.

[0144] Environmental protection measures

[0145] Water and frozen soil protection: Construction wastewater shall be treated by sedimentation and oil separation to meet discharge standards or be recycled. Direct discharge into the conservation area is strictly prohibited. Optimize processes to reduce thermal disturbance to the frozen soil layer. The stripped topsoil shall be centrally cured and used for subsequent revegetation.

[0146] Dust and solid waste control: Dust control measures such as watering and covering are adopted; construction waste is disposed of in a classified manner.

[0147] Ecological restoration: After construction, the temporary land occupied should be leveled in a timely manner, and vegetation should be restored using the original topsoil to ensure harmony with the surrounding environment.

[0148] Resource conservation

[0149] Material optimization and utilization

[0150] The project focuses on three dimensions: optimized material utilization, long-term maintenance-free design, and ecological protection. By adopting prefabricated C30 concrete slab covers for the side ditches and standardized permeable pipes, on-site processing losses are reduced, and material utilization is increased by approximately 15%.

[0151] Minimal environmental disturbance

[0152] By precisely locating groundwater diversion paths, large-scale excavation is avoided; construction wastewater achieves a 90% sedimentation and recycling rate, and all topsoil is cured and reused, maximizing the protection of native vegetation and water systems in the high-altitude ecological conservation area. Its resource-saving benefits encompass materials, energy consumption, labor, and ecology, providing a technological model for sustainable highway construction in high-altitude regions.

[0153] Economic benefits

[0154] The project implemented an active underground drainage method for ice flow in high-altitude and cold-weather roadbeds, ensuring that the roadbed and pavement were not damaged. The treated route was 3056 meters long, with 3383 meters of drainage trenches. The initial construction cost was 2.1323 million yuan, but the long-term economic benefits are significant. By eliminating ice flow at its source, the project avoided potential huge losses such as traffic disruptions, accident handling, and major road repairs caused by ice flow, greatly improving road traffic safety and operational efficiency, and enhancing the overall economic benefits throughout the road's lifecycle.

[0155] Table 5 Economic Benefit Analysis (Yuan / m)

[0156] Social benefits

[0157] This method significantly improves driving safety and reliability on highways in high-altitude and cold regions, effectively ensuring the smooth flow of goods transportation, people's travel, and emergency rescue channels in border areas. As a key technological guarantee for international transportation corridors, its application strongly supports cross-border logistics efficiency and the implementation of national strategies. Simultaneously, by protecting the permafrost environment and reducing ecological disturbance, this method promotes harmonious coexistence between engineering and the natural environment, and provides a replicable technological model for similar regions, possessing broad social demonstration value.

[0158] Application Examples

[0159] The third contract section of the G315 Topa-Turugart Port Highway Project is located in Wuqia County, Kizilsu Kyrgyz Autonomous Prefecture, Xinjiang. The highway is classified as a Class I highway. The third contract section is 32.664 km long, with a design speed of 100 km / h and a roadbed width of 26 m. The section from K106+000 to K111+500 is situated in a seasonally frozen soil area at an altitude of 3600-3800 m, and is also a high-altitude water conservation ecological protection zone with dense vegetation and high soil moisture content. Due to topographical constraints and ecological red lines, the design route partially utilized excavation sections. Construction disrupted the original balance, cut off interlayer water flow channels, and caused icing in the roadbed.

[0160] This method was specifically applied in the third section of the G315 Topa-Turugart highway construction project in Kizilsu Kyrgyz Autonomous Prefecture. In this project, the method was used to treat a 3056-meter section of the road with 3383 meters of infiltration trenches. Surface runoff was effectively intercepted, and deep groundwater was systematically drained through the infiltration trench system. After a complete freeze-thaw cycle, the previously severely ice-laden sections were completely eliminated, the roadbed structure remained stable, and no frost heave or spring frost heave occurred on the pavement, significantly reducing maintenance costs. This case demonstrates the effectiveness of this method under complex hydrogeological conditions in cold regions, providing a reliable technical example and engineering practice experience for highway construction and maintenance in similar environments.

[0161] The above-disclosed embodiments are merely one or more preferred embodiments of this application and should not be construed as limiting the scope of this application. Those skilled in the art can understand that all or part of the processes for implementing the above embodiments and equivalent changes made in accordance with the claims of this application still fall within the scope of this application.

Claims

1. A method for active underground drainage of ice flow in high-altitude and cold-weather roadbeds, characterized in that, Includes the following steps: Complete data collection and site survey, conduct water property analysis and meltwater volume estimation, and then carry out special planning for the drainage system; Conduct surveying and setting out, mark the axis of the seepage ditch and the excavation boundary line according to the design coordinates, set control stakes and mark the excavation depth and base elevation; Excavation of seepage trenches; Substrate treatment to ensure a solid base; Construction of cast-in-place concrete at the bottom of the seepage trench; Inspection well construction; Several seepage holes are machined on one side of the top surface of the PE200mm double-wall corrugated pipe before it is laid into the seepage trench. The seepage trenches were backfilled in layers; Construction of covered ditch; Installation of seepage trench outlets; System integration and acceptance.

2. The active underground drainage method for ice flow in high-altitude and cold-weather roadbeds as described in claim 1, characterized in that, In the steps of surveying and setting out, marking the seepage ditch axis and excavation boundary line according to the design coordinates, setting control stakes and marking the excavation depth and base elevation: Using surveying instruments, the axis of the seepage ditch and the excavation boundary line are laid out according to the design coordinates. Control stakes are set every 5m to mark the excavation depth and the elevation of the concrete foundation base. The longitudinal main pipe is set on one side of the mountain or the side of the water direction. The longitudinal slope is set at 3% according to the route design, and the transverse pipe is set at 3%. Suitable drainage points and crossing structures are selected for setting.

3. The active underground drainage method for ice flow in high-altitude and cold-weather roadbeds as described in claim 2, characterized in that, In the steps of excavating a seepage trench: The excavation depth is 3 meters, and the excavator is used for layered slope excavation to avoid over-excavation; the base is cleaned manually.

4. The underground active drainage construction method for ice flow in high-altitude and cold-weather roadbeds as described in claim 3, characterized in that, In the process of substrate treatment to ensure the substrate is solid: After the seepage trench is excavated, the base is compacted using a wheeled excavator with a hydraulic plate compactor; if the base is soft soil, it is replaced with 30cm thick gravel and compacted to the design requirements.

5. The active underground drainage construction method for ice flow in high-altitude and cold-weather roadbeds as described in claim 4, characterized in that, In the process of constructing cast-in-place concrete at the bottom of the seepage trench: For template installation, wooden or steel templates are used, the inside is coated with release agent and fixed, and sponge strips are pasted at the template joints to prevent grout leakage. Concrete pouring is carried out using tanker trucks for transportation and manual vibration, following the principle of pouring in layers from low to high, and the surface is then smoothed.

6. The active underground drainage construction method for ice flow in high-altitude and cold-weather roadbeds as described in claim 5, characterized in that, In the steps of manhole construction: Based on the longitudinal pipe diameter and for ease of daily inspection and maintenance, the inspection well is set to a diameter of 1 meter and a height of 3 meters. The pipe section adopts C30 reinforced concrete precast pipe body with internal steel ladder. During prefabrication, drainage pipe holes are reserved according to the longitudinal and transverse PE 200mm corrugated pipe positions. After installation, an 8cm polyurethane insulation board is installed 1 meter below the pipe section at the inspection well opening to isolate cold air in winter.

7. The active underground drainage construction method for ice flow in high-altitude and cold-weather roadbeds as described in claim 6, characterized in that, In the step of machining several seepage holes on one side of the top surface of a PE200mm double-wall corrugated pipe and then laying it into the seepage trench: A seepage hole is processed on one side of the top surface of the PE200mm double-wall corrugated pipe. The diameter of the seepage hole is 2cm and the spacing is controlled at 5-10cm to form a semi-arc permeable pipe. For pipeline laying, perforated corrugated pipes are installed according to the planned slope with the perforated side facing upwards. The bottom of the pipe is partially enclosed with concrete. Pipe section connections use socket joints, and the joints are sealed with rubber sealing rings and tightly wrapped with permeable geotextile. The perforated corrugated pipe is wrapped with permeable geotextile to ensure complete coverage of the perforated area.

8. The active underground drainage method for ice flow in high-altitude and cold-weather roadbeds as described in claim 7, characterized in that, In the process of backfilling the seepage trench in layers: Medium-coarse sand was used to backfill the sides of the pipeline, symmetrically from both sides of the pipeline, and compacted with a plate vibrator until it was flush with the top surface of the concrete foundation. A second layer of geotextile is laid, and the permeable geotextile is fully covered with a medium-coarse sand layer, with the edges wrapped up to the top of the seepage ditch. For gravel filling, clean 30-50mm gravel is filled in layers, each layer is 30cm, and compacted using a hydraulic plate rammer with an excavator. A 20cm space is left on the top surface. For the top sealing and roadbed backfilling, coarse sand is used for the top sealing, followed by a 20cm thick layer of medium-coarse sand, and the surface is leveled and compacted. Geogrid laying: The geogrid is fully laid along the longitudinal direction of the seepage ditch, with a width of 4m, and is compacted together with the subgrade fill.

9. The active underground drainage construction method for ice flow in high-altitude and cold-weather roadbeds as described in claim 8, characterized in that, In the construction steps of the cover ditch: A precast concrete side ditch with a cover plate is set on one side of the road cut section. The side ditch is arranged with a width of 80cm and a height of 80cm. The top elevation of the side ditch cover plate is controlled to connect smoothly with the cross slope of the hard shoulder, so as to facilitate smooth and unobstructed road surface drainage.

10. The active underground drainage method for ice flow in high-altitude and cold-weather roadbeds as described in claim 9, characterized in that, In the steps of setting up the seepage trench outlet: According to the longitudinal and transverse seepage trenches arranged in a comb pattern, and based on their longitudinal slope and the characteristics of the site, the drainage should be directed to a location 10-20 meters away from the route. Inspection wells should be set at the nodes, and 3-5 drainage pipes should be installed at the same time. The drainage pipes should be permeable pipes with open sections. The drainage pipes should be covered with an insulation layer around them and topped with backfilled rubble stones to ensure that the backfill of the drainage pipes is more than 3 meters deep.

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