Railway track bed reinforcement temperature control structure and method in permafrost region and storage medium

Abstract

The application discloses a permafrost region railway track roadbed reinforcing and temperature controlling structure, method and storage medium, and the roadbed reinforcing and temperature controlling structure comprises, from top to bottom, a steel rail, a sleeper, a subgrade surface layer, a subgrade bottom layer and an embankment; a transverse ventilation pipe is arranged below the embankment; a plurality of gravel piles are arranged at the bottom of the transverse ventilation pipe; the pile body of the gravel pile is a porous structure formed by gravel filling and is communicated with the transverse ventilation pipe; the gravel pile at the soft soil foundation layer is wrapped by an economical geogrid; the gravel pile at the future maximum soft layer and the safety reserve layer is wrapped by a high-strength geogrid; and the gravel pile at the permafrost layer is not wrapped. The application adopts the composite wrapped gravel pile reinforcing structure to reinforce the foundation based on the degradation position of the permafrost, simultaneously reduces the deep soil temperature through the temperature controlling structure, maintains the stability of the permafrost layer, and improves the stability of the reinforcement.

Description

Technical Field

[0001] This invention belongs to the field of road auxiliary electronic equipment technology, and relates to a temperature control structure, method and storage medium for reinforcing railway track subgrade in permafrost areas. Background Technology

[0002] The high-speed railway subgrade is a fundamental engineering structure that bears the track structure and train loads, and is a crucial link in ensuring the high-speed, safe, and stable operation of trains. Due to the combined effects of global warming and engineering thermal effects, permafrost degradation is becoming increasingly severe. In particular, the high-ice-content soil layer at the upper limit of permafrost is prone to forming weak interlayers after thawing, significantly increasing the risk of thaw settlement in the subgrade. Simultaneously, under the long-term cyclical action of train dynamic loads, the supergrade and track structure are prone to deformation and settlement, which may lead to structural instability in severe cases, further exacerbating the safety risks during the operation of railway engineering facilities. Summary of the Invention

[0003] To address the aforementioned issues, this invention provides a temperature-controlled reinforcement structure for railway track subgrade in permafrost regions. Based on the degradation location of the permafrost, a composite-encased crushed stone pile reinforcement structure is used to reinforce the foundation. Simultaneously, the temperature-controlled structure reduces the temperature of the deep soil, maintains the stability of the permafrost layer, and enhances the stability of the reinforcement.

[0004] The second objective of this invention is to provide a temperature control method for a temperature-controlled structure for reinforcing railway track subgrade in permafrost regions.

[0005] A third objective of this invention is to provide a computer storage medium.

[0006] The technical solution adopted in this invention is a temperature control structure for reinforcing railway track subgrade in permafrost areas, which includes, from top to bottom, rails, sleepers, subgrade surface layer, subgrade bottom layer and embankment. A transverse ventilation pipe is provided below the embankment, and multiple crushed stone piles are provided at the bottom of the transverse ventilation pipe. The crushed stone piles are porous structures filled with crushed stone and are connected to the transverse ventilation pipe.

[0007] The gravel piles in the soft soil base layer are wrapped with economical geogrids, while the gravel piles in the future maximum weak layer and safety reserve layer are wrapped with high-strength geogrids; the gravel piles in the permafrost layer are not wrapped.

[0008] Furthermore, the transverse ventilation pipe includes a hollow ventilation plate, with multiple first ventilation openings at the lower part of the hollow ventilation plate. A perforated steel plate is installed at each of the first ventilation openings and is fixedly connected to the hollow ventilation plate. The top of the crushed stone pile is in contact with the perforated steel plate. Multiple second ventilation openings are installed on the side of the hollow ventilation plate, with folding dampers installed at each of the second ventilation openings. An air pump is installed inside the hollow ventilation plate, and both the folding dampers and the air pump are connected to the intelligent control system.

[0009] The intelligent control system dynamically controls the opening and closing status of the folding damper, the start and stop status of the air pump, and the air extraction speed based on environmental monitoring data.

[0010] Furthermore, the hollow ventilation panel is equipped with several solid load-bearing columns to share the load of the road surface structure above the transverse ventilation pipe.

[0011] Furthermore, the material of the economical geogrid is polypropylene, polyethylene, or high-density polyethylene, and the node strength depends on the strength of the substrate itself without any additional reinforcement treatment.

[0012] Furthermore, the high-strength geogrid is made of polyester, high-strength polypropylene, or high-strength high-density polyethylene, and the nodes are reinforced by weaving followed by coating curing or welding to improve strength.

[0013] A method for temperature control of a railway track subgrade reinforcement and temperature control structure in permafrost regions includes the following steps:

[0014] S1, Prediction of the depth of weak interlayer under future meteorological scenarios: Calculate the location of the upper limit of permafrost degradation at a fixed time in the future. Calculate the thickness of the future maximum weak layer by the depth difference between the known initial upper limit of permafrost and the calculated location of the upper limit of permafrost degradation. Then, combine the engineering safety level and design requirements to obtain the thickness of the safety reserve layer. The crushed stone piles at the future maximum weak layer and the safety reserve layer are wrapped with high-strength geogrid.

[0015] S2 regulates the temperature of the soil around the crushed stone piles through the horizontal ventilation pipe.

[0016] Furthermore, in S1, the method for predicting the depth of weak interlayers under future meteorological scenarios includes the following steps:

[0017] The spatial attenuation characteristics of temperature are described using the penetration depth δ of thermal waves. A one-dimensional temperature distribution formula for railway track subgrade soil in permafrost regions is established as follows:

[0018] (1)

[0019] In the formula: T(x) represents the temperature at a subgrade depth of x; x represents the depth of the subgrade soil, with positive values ​​for vertically downward. It is the depth of heat wave penetration. ; It is the temperature of the subgrade soil at depth x=0, i.e., the surface temperature; α is the relative stable temperature of the soil below the upper limit of the frozen soil; m is the model parameter, calculated from the initial surface temperature and the initial upper limit of the frozen soil; P is the period; α is the thermal diffusivity.

[0020] In the permafrost model, the surface temperature Taking the lowest annual temperature value and considering the impact of global warming, the surface temperature... It can be expressed in the following function form:

[0021] (3)

[0022] In the formula: Indicates surface temperature Function for change over time t; A represents the annual average temperature, M represents the amplitude of the annual temperature variation, ΔT represents the rate of annual temperature increase due to global warming; t represents time;

[0023] Upper limit depth of permafrost Defined as the depth at which the temperature drops to 0°C; T(x) f Substituting 0 into equation (1), we obtain the formula for calculating the upper limit depth of frozen soil:

[0024] (4)

[0025] The simplified formula for calculating the final upper limit depth of permafrost is as follows:

[0026] (5)

[0027] This allows us to determine the upper limit of permafrost degradation location.

[0028] Furthermore, S2 includes the following steps:

[0029] S21, the intelligent control system acquires real-time data of ambient temperature, rainfall, and pressure inside the ventilation duct through the sensing system and stores it in the data storage unit;

[0030] S22, the processor periodically executes control instructions at set time intervals, comparing the current ambient temperature with a set temperature threshold:

[0031] If the ambient temperature is below the temperature threshold, open the folding damper and continue to determine if there is rainfall. If there is no rainfall, keep the folding damper open; if there is rainfall, close the folding damper to prevent rainwater from entering the ventilation duct.

[0032] If the ambient temperature is higher than the temperature threshold, the folding damper is closed; continue to check whether the pressure inside the ventilation duct exceeds the set pressure threshold. If it exceeds the threshold, the air pump is turned off; if it is lower than the threshold, the air pump is started to make the hollow ventilation panel a near-vacuum environment.

[0033] The opening and closing status of the folding damper, the start and stop status of the air pump, and the corresponding execution time are synchronously recorded in the data storage unit.

[0034] Furthermore, the vacuum level inside the hollow ventilation panel is controlled between 100 Pa and 1000 Pa.

[0035] A computer storage medium storing computer program code, which, when executed by a processor, implements the temperature control method described above for a temperature control structure for reinforcing railway track subgrade in permafrost regions.

[0036] The beneficial effects of this invention are:

[0037] This invention predicts the depth of weak interlayers under future meteorological scenarios, taking into account the impact of global warming. Based on the temperature distribution of the roadbed soil, the degradation location of permafrost is determined, and the area between the initial permafrost upper limit and the degradation location is defined as the weak interlayer (i.e., the future maximum weak layer). According to the engineering safety level and design requirements, a reasonable safety factor is determined, and the thickness of the future maximum weak layer is multiplied by this factor to calculate the range of the safety reserve layer thickness.

[0038] This invention employs a composite-wrapped crushed stone pile reinforcement structure to treat the foundation. Based on the calculated thickness range of the weak interlayer and safety reserve layer, different types of geogrids are selected to wrap the crushed stone pile foundation. Economical geogrids are used for wrapping in soft soil base layers, while reinforced geogrids are used for wrapping in the future weakest layer and safety reserve layer. Unwrapped crushed stone sections are used in permafrost layers, thereby achieving efficient integration of the base soil and material properties, which not only meets engineering requirements but also effectively reduces costs.

[0039] This invention constructs an intelligent temperature-controlled transverse ventilation duct-crushed stone pile composite structure. This structure uses an intelligent control system to collect environmental parameters such as temperature, rainfall, and pressure within the ventilation duct in real time, and automatically decides on temperature control measures based on the comprehensive judgment results. In winter, when temperatures are low, the system intelligently controls the opening of the ventilation dampers, utilizing air convection to allow cold air to flow within the ventilation duct and crushed stone piles, effectively reducing the temperature of the deep soil, achieving subgrade temperature control, and maintaining the stability of the permafrost layer. In summer, when temperatures are high, the system intelligently closes the ventilation dampers and activates the air pump to create a near-vacuum environment within the ventilation duct, significantly reducing the heat exchange efficiency between the ventilation duct and the high-temperature outside air. This effectively blocks the transfer of summer heat to the frozen soil, preventing or slowing down permafrost thawing, and improving the long-term stability and operational safety of railway subgrades in permafrost regions. Attached Figure Description

[0040] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0041] Figure 1 This is a schematic diagram of a railway track subgrade reinforcement and temperature control structure in permafrost regions according to an embodiment of the present invention.

[0042] Figure 2 This is a schematic diagram of the structure of the intelligent temperature-controlled horizontal ventilation duct in an embodiment of the present invention.

[0043] Figure 3 This is a block diagram of the execution logic of the processor control instructions in an embodiment of the present invention.

[0044] 1. Rail, 2. Sleeper, 3. Subgrade surface layer, 4. Subgrade bottom layer, 5. Embankment, 6. Folding ventilation door, 7. Transverse ventilation pipe, 8. Crushed stone pile, 9. Economic geogrid, 10. Soft soil base layer, 11. Initial frozen soil upper limit, 12. High-strength geogrid, 13. Future maximum weak layer, 14. Safety reserve layer, 15. Frozen soil upper limit degradation location, 16. Permafrost layer, 17. Hollow ventilation board, 18. First ventilation opening, 19. Perforated steel plate, 20. Solid bearing column, 21. Second ventilation opening, 22. Air pump. Detailed Implementation

[0045] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0046] A temperature-controlled structure for reinforcing railway track subgrade in permafrost regions, such as Figure 1 As shown, from top to bottom, the components are: 1. Rail, 2. Sleeper, 3. Subgrade surface layer, 4. Subgrade bottom layer, 5. Embankment, 6. Folding ventilation door, 7. Transverse ventilation pipe, 8. Crushed stone pile, 9. Economic geogrid, 10. Soft soil base layer, 11. Initial frozen soil upper limit, 12. High-strength geogrid, 13. Future maximum weak layer, 14. Safety reserve layer, 15. Frozen soil upper limit degradation location, 16. Permafrost layer.

[0047] The crushed stone pile 8 is located below the intelligent temperature-controlled transverse ventilation pipe 7. The crushed stone pile 8 is composed of crushed stone, soil, and air gaps, which has good air permeability and provides an effective channel for cold air to flow inside the roadbed. According to the differences in the mechanical properties of the soil, the crushed stone pile foundation is compositely wrapped with a "rigid and flexible" design concept. An economical geogrid 9 is used for wrapping the soft soil base layer 10, a high-strength geogrid 12 is used for wrapping the future maximum weak layer 13 and the safety reserve layer 14, and an unwrapped crushed stone section is used in the permafrost layer 16, thus making the crushed stone pile 8 a composite wrapped crushed stone pile foundation structure.

[0048] The design principle of the composite-wrapped crushed stone pile foundation structure is as follows: Utilizing the method of predicting the depth of weak interlayers under future weather scenarios, combined with the engineering safety level and design requirements, the upper limit degradation position 15 of the frozen soil at a certain future time is calculated. The area between the initial upper limit of the frozen soil 11 and the upper limit degradation position 15 is the future maximum weak layer 13. Therefore, the thickness of the future maximum weak layer 13 can be calculated by the depth difference between the known initial upper limit of the frozen soil 11 and the calculated upper limit degradation position 15. The thickness of the future maximum weak layer 13 is then multiplied by a safety factor to calculate the thickness of the safety reserve layer 14, which is located below the future maximum weak layer 13.

[0049] In the soft soil base course 10, a geogrid with moderate strength and cost, such as a plastic geogrid, is used to wrap the gravel piles 8. In the future maximum weak layer 13 and the safety reserve layer 14, a higher strength geogrid, such as a steel-plastic geogrid, is used to wrap the gravel piles 8, and steel reinforcement hoops are used where necessary to enhance the lateral restraint of the gravel pile foundation, prevent lateral deformation, and avoid thaw settlement in the future maximum weak layer 13. Due to the high strength of the frozen soil, unwrapped gravel sections are used in the permafrost layer 16 to achieve efficient integration of the base soil and material properties, meeting engineering requirements while effectively reducing costs.

[0050] Economic geogrids (9) specifically refer to geogrid products that meet basic reinforcement functions, have low cost, and are suitable for general loads or non-critical parts. Common materials include polypropylene, polyethylene, and high-density polyethylene. Structurally, they are mostly manufactured using stretching or weaving processes. The strength of the joints mainly depends on the strength of the substrate itself, without additional reinforcement treatment. The manufacturing process is relatively simple, and the production cost is low.

[0051] High-strength geogrid 12 refers to products with higher mechanical properties (especially tensile strength and modulus) compared to economical geogrids, suitable for high-load or critical components. Common materials include polyester, high-strength polypropylene, and high-strength high-density polyethylene. Structurally, they are mostly manufactured using warp knitting or welding processes. The strength of the joints is improved by coating and curing after weaving or by welding reinforcement, and the material itself has higher strength than economical geogrids.

[0052] The structure of the intelligent temperature-controlled horizontal ventilation duct 7 is as follows: Figure 2 As shown, the structure includes a hollow ventilation panel 17, with several first ventilation openings 18 at the bottom. Perforated steel plates 19 are installed at each of the first ventilation openings 18 and are fixedly connected to the hollow ventilation panel 17. To ensure structural load-bearing capacity, several solid load-bearing columns 20 are installed inside the hollow ventilation panel 17 to share the load of the road surface structure above the transverse ventilation pipe 7, ensuring structural stability and road safety.

[0053] The perforated steel plate 19 is located at the top of the crushed stone pile 8, and the two are in direct contact without any additional manual connection. This structural design allows the load at the bottom of the transverse ventilation pipe 7 to be evenly transferred to the top of the crushed stone pile 8 through the perforated steel plate 19. The perforations on the steel plate ensure unobstructed airflow, achieving ventilation and heat dissipation functions, while also taking into account load-bearing and force transmission functions. Thus, while maintaining good air permeability, it ensures the overall stress stability and structural safety between the transverse ventilation pipe 7 and the crushed stone pile 8.

[0054] The hollow ventilation panel 17 has several second ventilation openings 21 on its side. Folding dampers 6 are installed at the second ventilation openings 21. An air pump 22 is installed inside the transverse ventilation pipe 7. Both the folding dampers 6 and the air pump 22 are connected to the intelligent control system. The intelligent control system dynamically controls the opening and closing status of the folding dampers 6 and the start and stop status of the air pump 22 based on environmental monitoring data.

[0055] The intelligent control system integrates a sensing system, a data acquisition system, electronic equipment, computer storage media, and solar power supply equipment.

[0056] The sensing system includes: a temperature sensor for real-time monitoring of ambient temperature, a tipping bucket rain gauge for monitoring rainfall, and a pressure sensor for monitoring the pressure inside the hollow ventilation panel.

[0057] The electronic device includes a memory (for storing instructions to be executed by a processor) and a processor, which executes intelligent control instructions for the folding damper and air pump according to a set program logic.

[0058] The computer storage medium is used to store program logic, data collected by sensors, and execution data on the opening and closing status of the folding damper 6 and the start and stop status of the air pump 22.

[0059] A method for temperature control of a railway track subgrade reinforcement and temperature control structure in permafrost regions includes the following steps:

[0060] S1, Prediction of the depth of weak interlayers under future meteorological scenarios;

[0061] The spatial attenuation characteristics of temperature are described using the penetration depth δ of thermal waves. A one-dimensional temperature distribution formula for railway track subgrade soil in permafrost regions is established as follows:

[0062] (1)

[0063] In the formula: T(x) represents the temperature at a subgrade depth of x; x represents the depth of the subgrade soil, with positive values ​​for vertically downward. It is the depth of heat wave penetration. This reflects the temperature decay characteristics with depth. It is the temperature of the subgrade soil at depth x=0. That is, the surface temperature. It is the relative stable temperature of the soil below the upper limit of the frozen soil. m is a model parameter, calculated from the initial surface temperature and the initial upper limit of the frozen soil.

[0064] In equation (1), based on the preliminary survey data, the relative stable temperature of the soil below the upper limit of the frozen soil can be determined. Thermal wave penetration depth It can be calculated based on the thermophysical parameters of the soil layers. When the initial surface temperature... and the initial upper limit of the permafrost (the depth value at this location can be denoted as...). The temperature at the upper limit of the permafrost is 0 ℃, which means... When the parameter is known, only the parameter remains in equation (1). Since it is an unknown quantity, it can be obtained by substituting it into the known conditions mentioned above. The value of .

[0065] After taking into account the effects of global warming, the initial surface temperature The parameters will change accordingly. Given that the penetration depth of the heat wave is... The relative stable temperature of the soil below the upper limit of the frozen soil The given constant is denoted as . Substituting the given parameters into equation (1), the upper limit depth of the final frozen soil when the temperature is 0℃ can be calculated.

[0066] P is the period (e.g., one year, i.e., 365 × 24 × 3600 s). α is the thermal diffusivity, used to describe the thermal conductivity of a material, defined as the rate at which temperature diffuses through the material per unit time, calculated as follows:

[0067] (2)

[0068] In the formula: It is the thermal conductivity of the material (unit: W / (m·K)). It is the density of the material (unit: kg / m³). It is the specific heat capacity of the material (unit: J / (kg·K)).

[0069] In the permafrost model, the surface temperature Taking the lowest annual temperature value and considering the impact of global warming, the surface temperature... It can be expressed in the following function form:

[0070] (3)

[0071] In the formula: Indicates surface temperature The function represents the change of temperature over time t; A represents the annual average temperature, M represents the amplitude of the annual temperature change, ΔT represents the rate of annual temperature increase due to global warming, t represents time (unit: year), and ΔTt represents the amount of temperature increase due to global warming after t years.

[0072] Upper limit depth of permafrost Defined as the depth at which the temperature drops to 0°C. According to the temperature distribution formula, T(x) f Substituting 0 into equation (1), we can obtain the formula for calculating the upper limit depth of frozen soil:

[0073] (4)

[0074] The simplified formula for calculating the final upper limit depth of permafrost is as follows:

[0075] (5)

[0076] Existing mainstream techniques for calculating the upper limit degradation location of permafrost mostly rely on solving partial differential equations or conducting numerical simulations based on physical processes. These methods involve large computational loads, time-consuming solutions, and are sensitive to boundary conditions and material parameters, making them unsuitable for rapid application in engineering fields. The formula (5) proposed in this embodiment of the invention is a simple prediction method that significantly reduces computational complexity and time consumption while maintaining reasonable engineering accuracy. It facilitates the rapid and convenient estimation of the upper limit degradation location of permafrost during engineering design and construction. It also enables reliable estimation results even when parameters are incomplete or computational resources are limited. Furthermore, it reduces the dependence on detailed initial / boundary conditions and high-density numerical grids, thereby reducing the workload of on-site data acquisition and numerical solution.

[0077] The calculation formula for the upper limit depth of permafrost was verified using data from existing technology 1 (Dong Yuanhong, Peng Hui, Luo Tao, et al. Characteristics of permafrost degradation in typical sections along the proposed Qinghai-Tibet Expressway over the next 50 years under the background of climate warming [J]. Catastrophology, 2019, 34(S1):20-25). The thermophysical parameters of the soil layers in areas A and B along the Qinghai-Tibet Expressway are shown in Table 1.

[0078] Table 1 Thermophysical parameters of soil layers

[0079]

[0080] The IPCC (Intergovernmental Panel on Climate Change) predicts that the global average temperature will increase by 1.4 to 5.8°C in the 21st century. Table 2 shows the warming rates corresponding to the three climate change scenarios predicted in the IPCC report.

[0081] Table 2. Warming rates corresponding to different climate change scenarios

[0082]

[0083] Table 3 shows the surface temperature conditions and permafrost upper limit in regions A and B in 2014.

[0084] Table 3. Surface temperature conditions and initial permafrost limit in 2014

[0085]

[0086] Taking region A as an example to demonstrate the verification process, the initial surface temperature conditions and initial permafrost upper limit in region A in 2014 were as follows: To better reflect the effects of freeze-thaw cycles, the period P is set to six months, i.e., P = 0.5 × 365 × 24 × 3600 seconds. The relative stable temperature of the soil below the upper limit of the frozen soil is taken as... According to literature, the annual minimum temperature conditions in region A are as follows:

[0087]

[0088] First, substitute the initial value to calculate the parameter m. The calculation process is as follows:

[0089]

[0090]

[0091]

[0092] The calculation yielded m=0.523m. Then, based on the warming rate under different climate change scenarios in Table 2, the upper limit depth of permafrost after 50 years was calculated using formula (5), and the results are shown in Table 4.

[0093] Table 4. Predicted upper limits of permafrost in 2064 under different warming rates

[0094]

[0095] Table 4 shows the numerical prediction values ​​for the upper limit depth of permafrost predicted using the numerical calculation method in prior art 1. The data in Table 4 shows that the upper limit value of permafrost in 2064 calculated using the prediction formula is close to the numerical prediction results in the literature, indicating that the formula calculation method has high accuracy. Note: During the verification process, it was found that when the thermal wave penetration depth is close to the initial upper limit depth of permafrost, a reduction factor needs to be multiplied by the thermal wave penetration depth; otherwise, the calculation results may have a large deviation. The calculated upper limit of permafrost many years later can be regarded as the degradation location of permafrost, and the area between the initial upper limit of permafrost and the degradation location can be regarded as the future maximum weak layer. To ensure project safety, a reasonable safety factor is determined according to the project safety level and design requirements. Multiplying the thickness of the future maximum weak layer by this safety factor yields the thickness range of the safety reserve layer.

[0096] The safety factor generally ranges from 1.2 to 2.0. The specific value should consider the following two factors: First, the type and importance of the project; critical projects should use a higher safety factor, while general projects can appropriately choose a lower one. Second, the complexity of the geological environment; the greater the uncertainty of the permafrost degradation process, the higher the safety factor should be. The specific value should be reasonably adjusted based on the project's risk assessment results and engineering experience to ensure that the design has sufficient safety margins and meets the actual engineering needs.

[0097] S2, temperature is controlled through intelligent temperature-controlled horizontal ventilation duct 7;

[0098] S21, the intelligent control system acquires real-time data of ambient temperature, rainfall, and pressure inside the ventilation duct through the sensing system and stores it in the data storage unit.

[0099] S22, the processor periodically executes control instructions at set time intervals, the program logic is as follows: Figure 3 As shown, compare the current ambient temperature with the set temperature threshold: (1) If the ambient temperature is lower than the temperature threshold, open the folding damper 6 and continue to determine whether there is rainfall. If there is no rainfall, keep the folding damper 6 open. If there is rainfall, close the folding damper 6 to prevent rainwater from entering the ventilation duct. (2) If the ambient temperature is higher than the temperature threshold, close the folding damper 6. Continue to determine whether the pressure inside the ventilation duct exceeds the set pressure threshold. If it exceeds the threshold, turn off the air pump 22; if it is lower than the threshold, start the air pump 22.

[0100] The opening and closing status of the folding damper 6, the start and stop status of the air pump 22, and the corresponding execution time are synchronously recorded in the data storage unit, which facilitates subsequent data analysis and strategy optimization.

[0101] The pile body of crushed stone pile 8 is filled with crushed stone and has a porous structure with interconnected pores. In summer, the surface air temperature rises, causing the soil temperature to rise. Even in winter, although the surface air temperature drops significantly, the temperature of the deep soil in the roadbed remains significantly higher than the surface air temperature. This is because soil has a large heat capacity and thermal inertia, making the response of deep soil to air temperature changes more slow. Furthermore, vertically, the surface layer of soil is more affected by air temperature changes and cools down faster in winter, while the deep soil is less affected by surface cooling and its temperature drops more slowly, forming a significant temperature gradient. Therefore, the temperature of the deep soil in the roadbed is significantly higher than the surface air temperature in winter.

[0102] When the temperature is low in winter, the system intelligently controls the opening of the folding air door 6, using air convection to introduce cold air into the hollow ventilation plate 17. The cold air can then flow through the first ventilation opening 18 inside the hollow ventilation plate 17 and the crushed stone pile 8, and continuously exchange heat with the roadbed soil (this heat exchange is driven by the temperature difference between the cold air and the soil, and the temperature difference range generally depends on the surface air temperature and soil temperature in winter, usually from several degrees Celsius to more than ten degrees Celsius), effectively reducing the temperature of the deep soil, achieving the purpose of cooling the roadbed, realizing roadbed temperature control, and maintaining the stability of the permafrost layer.

[0103] When summer temperatures are high, the system intelligently closes the folding damper 6 and starts the air pump 22 to extract air, creating a near-vacuum environment (vacuum degree controlled between 100Pa and 1000Pa) inside the ventilation duct (i.e., inside the hollow ventilation plate 17). In the near-vacuum environment, gas molecules are extremely rare (very few in number), resulting in a significant reduction in heat conduction. This significantly reduces the heat exchange efficiency between the ventilation duct and the outside high-temperature air, effectively blocking the transfer of summer heat to the frozen soil in winter, avoiding or slowing down the thawing of permafrost, and improving the long-term stability and operational safety of railway subgrade in permafrost areas.

[0104] This intelligent control system enables real-time automated control of ventilation pipe dampers and air pumps in railway track subgrades in permafrost regions, ensuring temperature control safety and energy consumption optimization for railway track subgrades in permafrost areas.

[0105] Compacted soil significantly reduces the gas permeability coefficient by decreasing the effective porosity and disrupting pore connectivity. Under freezing conditions, pore water freezes, further sealing the airflow channels and significantly reducing gas permeability. Therefore, even if the hollow ventilation plate 17 remains connected to the crushed stone pile 8, the compacted soil surrounding the crushed stone pile 8 can still act as a "natural" flow barrier, limiting gas leakage through the interface. As long as the effective pumping speed of the vacuum pump 22 (the net gas extraction capacity of the vacuum pump 22 at the target working pressure) is greater than the total leakage flow generated by the connecting channel and the surrounding soil, the system can establish and maintain the expected steady-state negative pressure field, achieving vacuuming of the hollow ventilation plate 17. For conditions with coarser soil particles or requiring higher vacuum levels, a thin, thermally conductive plastic film or air-tight membrane can be added to the outside of the composite-wrapped crushed stone pile 8 to further reduce leakage and improve airtight reliability. Cold air flows inside the hollow ventilation plate 17 and the crushed stone pile 8, and continuously exchanges heat with the subgrade soil. This heat exchange is driven by the temperature difference between the cold air and the soil. The temperature difference range generally depends on the surface air temperature and soil temperature in winter, and is usually several degrees Celsius to more than ten degrees Celsius.

[0106] During the system vacuuming phase, the pumping speed of pump 22 is... It can be represented as:

[0107]

[0108] In the formula, This indicates the system gas leakage rate, which is the amount of air entering the system from the outside through interfaces or gaps per unit time. This represents the gas extraction rate required to achieve an increased negative pressure in a system without considering gas leakage. This is based on the principles of vacuum technology. It can be approximately calculated using the following formula:

[0109]

[0110] In the formula, This indicates the total volume of the horizontal ventilation pipe 7 and the crushed stone pile 8 system. and These represent the initial pressure and the target pressure of the system, respectively. Indicates the duration of air extraction. Once determined, the primary objective in calculating the pumping rate of the air pump 22 is to obtain the system's gas leakage rate, which can be determined through on-site pumping tests. Under steady-state conditions, the system pressure no longer changes, and the air flow rate pumped by the air pump 22 can be considered equal to the system leakage rate. .

[0111] On-site air extraction test procedure:

[0112] 1. Connect the air pump 22 and close the second vent 21;

[0113] 2. Start the vacuum pump 22 to reduce the system pressure to the target negative pressure;

[0114] 3. By adjusting the pumping speed of the air pump 22, maintain the system pressure near the target negative pressure for 5-10 minutes until the system pressure tends to stabilize. ;

[0115] 4. Record the pumping rate of the air pump 22 at this time. ,at this time That is equal to the system gas leakage rate. .

[0116] The system gas leakage rate was calculated. Then, the pumping rate can be controlled in stages:

[0117] Vacuuming stage: The speed of pump 22 is as follows The system is designed to achieve the target negative pressure within a specified time.

[0118] During the constant vacuum phase: During steady-state operation, the pumping capacity of pump 22 only needs to compensate for the leakage, i.e. To maintain stable negative pressure in the system.

[0119] In practical applications, excessively high pumping rates can lead to increased energy consumption and may cause leaks at the pipe pile interfaces or particle disturbance in the crushed stone piles 8. Insufficient pumping rates, on the other hand, can result in insufficient negative pressure and a low vacuum, thus weakening the vacuum insulation effect. To avoid these problems, the deviation between the measured and set pressure values ​​within the ventilation pipe and crushed stone pile system can be periodically checked. When the deviation is large, the system gas leakage rate can be recalculated according to the above test procedures, and the pumping rate of the pump 22 can be adjusted accordingly to ensure efficient and stable system operation.

[0120] This invention simplifies the multiphysics (thermal-phase transition-mechanical) coupling problem into a simple predictive form applicable to engineering, meeting the needs of rapid decision-making on-site while ensuring necessary computational accuracy. The intelligent temperature-controlled transverse ventilation duct can controllably switch between two mutually exclusive operating conditions: "winter ventilation and heat exchange" and "summer near-vacuum heat resistance." To achieve this function, the structure and operating strategy must consider two aspects: ensuring the connectivity and unobstructed flow of the ventilation channel under ventilation conditions; and under heat resistance conditions, the intelligent control system automatically makes decisions based on real-time monitoring data, precisely executing operating strategies such as damper closure, pump 22 startup, and pumping speed control to establish and maintain the required near-vacuum environment. While meeting the requirements of reinforced load-bearing and temperature control functions, and considering economy, a layered "rigid-flexible" grille wrapping strategy is proposed to achieve an optimal balance between mechanical strength and cost. An integrated sensing-control-energy system that enables adaptive operation on-site solves the engineering challenges of long-term monitoring, control reliability, and energy supply in harsh environments.

[0121] The temperature control method for the railway track subgrade reinforcement and temperature control structure in permafrost regions described in this invention, if implemented as a software functional module and sold or used as an independent product, can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this invention, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the temperature control method for the railway track subgrade reinforcement and temperature control structure in permafrost regions described in this invention. The aforementioned readable storage medium can be a USB flash drive, external hard drive, read-only memory (ROM), random access memory (RAM), magnetic disk, or optical disk, or any other readable storage medium capable of storing program code.

[0122] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention are included within the scope of protection of the present invention.

Claims

1. A temperature control method for a temperature-controlled structure for reinforcing railway track subgrade in permafrost regions, characterized in that, A temperature control structure for reinforcing railway track subgrade in permafrost areas is provided. From top to bottom, it includes rails (1), sleepers (2), subgrade surface layer (3), subgrade bottom layer (4) and embankment (5). A transverse ventilation pipe (7) is provided below the embankment (5). Multiple crushed stone piles (8) are provided at the bottom of the transverse ventilation pipe (7). The crushed stone piles (8) are porous structures filled with crushed stone and are connected to the transverse ventilation pipe (7). The gravel piles (8) at the soft soil base layer (10) are wrapped with economic geogrid (9), and the gravel piles (8) at the future maximum weak layer (13) and safety reserve layer (14) are wrapped with high-strength geogrid (12); the gravel piles (8) at the permafrost layer (16) are not wrapped. The transverse ventilation pipe (7) includes a hollow ventilation plate (17), with multiple first ventilation openings (18) at the bottom of the hollow ventilation plate (17). A perforated steel plate (19) is provided at the first ventilation opening (18), and the perforated steel plate (19) is fixedly connected to the hollow ventilation plate (17). The top of the crushed stone pile (8) is in contact with the perforated steel plate (19). Multiple second ventilation openings (21) are provided on the side of the hollow ventilation plate (17), and a folding air door (6) is provided at the second ventilation opening (21). An air pump (22) is provided inside the hollow ventilation plate (17), and both the folding air door (6) and the air pump (22) are connected to the intelligent control system. The intelligent control system dynamically controls the opening and closing status of the folding damper (6), the start and stop status of the air pump (22), and the air extraction speed based on environmental monitoring data. The hollow ventilation panel (17) is provided with several solid bearing columns (20) to share the load of the road surface structure above the transverse ventilation pipe (7); Includes the following steps: S1, Prediction of the depth of the weak interlayer under future meteorological scenarios, calculate the upper limit degradation position of the frozen soil at a fixed time in the future (15), calculate the layer thickness of the future maximum weak layer (13) by the depth difference between the known initial upper limit of frozen soil (11) and the calculated upper limit degradation position of frozen soil (15), and then combine the engineering safety level and design requirements to obtain the layer thickness of the safety reserve layer (14); the crushed stone piles (8) at the future maximum weak layer (13) and the safety reserve layer (14) are wrapped by high-strength geogrid (12); S2, temperature regulation of the soil around the crushed stone pile (8) is achieved through the transverse ventilation pipe (7).

2. The temperature control method for a temperature-controlled structure for reinforcing railway track subgrade in permafrost regions according to claim 1, characterized in that, The method for predicting the depth of weak interlayers under future meteorological scenarios in S1 includes the following steps: The spatial attenuation characteristics of temperature are described using the penetration depth δ of thermal waves. A one-dimensional temperature distribution formula for railway track subgrade soil in permafrost regions is established as follows: （1） In the formula: T(x) represents the temperature at a subgrade depth of x; x represents the depth of the subgrade soil, with positive values ​​for vertically downward. It is the depth of heat wave penetration. ; It is the temperature of the subgrade soil at depth x=0, i.e., the surface temperature; α is the relative stable temperature of the soil below the upper limit of the frozen soil; m is the model parameter, calculated from the initial surface temperature and the initial upper limit of the frozen soil; P is the period; α is the thermal diffusivity. In the permafrost model, the surface temperature Taking the lowest annual temperature value and considering the impact of global warming, the surface temperature... It can be expressed in the following function form: （3） In the formula: Indicates surface temperature; Function for change over time t; A represents the annual average temperature, M represents the amplitude of the annual temperature variation, ΔT represents the rate of annual temperature increase due to global warming; t represents time; Upper limit depth of permafrost Defined as the depth at which the temperature drops to 0°C; T(x) f Substituting 0 into equation (1), we obtain the formula for calculating the upper limit depth of frozen soil: （4） The simplified formula for calculating the final upper limit depth of permafrost is as follows: （5） Thus, the upper limit of permafrost degradation position is obtained (15).

3. The temperature control method for a temperature-controlled structure for reinforcing railway track subgrade in permafrost regions according to claim 1, characterized in that, S2 includes the following steps: S21, the intelligent control system acquires real-time data of ambient temperature, rainfall, and pressure inside the ventilation duct through the sensing system and stores it in the data storage unit; S22, the processor periodically executes control instructions at set time intervals, comparing the current ambient temperature with a set temperature threshold: If the ambient temperature is below the temperature threshold, the folding damper (6) is opened, and the system continues to determine whether there is rainfall. If there is no rainfall, the folding damper (6) is kept open. If there is rainfall, the folding damper (6) is closed to prevent rainwater from entering the ventilation duct. If the ambient temperature is higher than the temperature threshold, the folding damper (6) is closed; continue to judge whether the pressure in the ventilation duct exceeds the set pressure threshold. If it exceeds the threshold, the air pump (22) is turned off; if it is lower than the threshold, the air pump (22) is started, so that the hollow ventilation plate (17) is in a near-vacuum environment. The opening and closing status of the folding damper (6), the start and stop status of the air pump (22), and the corresponding execution time are synchronously recorded in the data storage unit.

4. The temperature control method for a railway track subgrade reinforcement and temperature control structure in permafrost regions according to claim 3, characterized in that, The vacuum level inside the hollow ventilation panel (17) is controlled between 100 Pa and 1000 Pa.

5. The temperature control method for a temperature-controlled structure for reinforcing railway track subgrade in permafrost regions according to claim 1, characterized in that, The economic geogrid (9) is made of polypropylene, polyethylene or high-density polyethylene, and the node strength depends on the strength of the substrate itself without any additional reinforcement treatment.

6. The temperature control method for a railway track subgrade reinforcement and temperature control structure in permafrost regions according to claim 1, characterized in that, The high-strength geogrid (12) is made of polyester, high-strength polypropylene or high-strength high-density polyethylene, and the nodes are reinforced by weaving, coating curing or welding to improve strength.

7. A computer storage medium storing computer program code, characterized in that, The computer program code, when executed by a processor, implements a temperature control method for a temperature-controlled structure for reinforcing railway track subgrade in permafrost regions as described in any one of claims 1-6.

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