Self-adaptive intelligent ventilation, temperature control and dehumidification system for frozen soil roadbed and regulation and control method

Abstract

The invention belongs to the technical field of frozen soil roadbed engineering and intelligent temperature control, and particularly relates to a self-adaptive intelligent ventilation, temperature control and dehumidification system for a frozen soil roadbed and a regulation and control method. The method comprises the following steps: calculating an input cooling capacity value according to dry-bulb temperature and moisture content of an air pipe inlet and an air pipe outlet; the dehumidification amount is calculated according to the moisture content and the dry air mass flow; air is input into the air pipe according to the input cooling capacity and the dehumidification capacity; detecting temperatures of different depths of the roadbed, and determining depth values of 0 DEG C at different moments; subtracting the depth value at 0 DEG C from a set depth value at 0 DEG C to obtain frozen soil upper limit deviation; if the frozen soil upper limit deviation is larger than the preset threshold value, the input cooling capacity is adjusted, and the annual target and the monthly target of the input cooling capacity are adjusted. According to the method, a roadbed thermal condition rapid calculation system is constructed, inter-year and intra-year dual regulation and control targets are determined, and self-adaptive control is realized.

Description

Technical Field

[0001] This invention belongs to the interdisciplinary field of frozen soil roadbed engineering and intelligent temperature control technology, specifically involving an adaptive intelligent ventilation, temperature control and dehumidification system and control method for frozen soil roadbeds. Background Technology

[0002] In the process of highway construction in permafrost regions, how to protect the underlying permafrost to avoid highway damage is a primary technical problem that needs to be solved.

[0003] Currently, existing frozen soil subgrade cooling technologies are divided into active cooling and passive cooling technologies.

[0004] (1) Stone roadbed In warm seasons, the temperature at the top of the rubble layer is higher than at the bottom, resulting in less heat convection and weakened heat transfer. Conversely, in cold seasons, the temperature at the top is lower than at the bottom, leading to enhanced heat convection and thus creating a "one-way thermal semiconductor" effect that increases cold input and reduces heat input. However, rubble layers require relatively uniform rubble size, which is difficult to control during actual construction. This results in the inclusion of small rubble pieces and the potential for wind and sand accumulation during roadbed operation, thereby reducing its unidirectional heat transfer efficiency.

[0005] (2) Ventilation duct foundation Ventilation duct roadbeds utilize the heat within the roadbed, driven by its own weight and wind, to carry away heat through pipes, thus achieving an active cooling measure to maintain the frozen state of the foundation soil. Embedding ventilation ducts in the roadbed effectively prevents the downward transfer of radiant heat absorbed by the roadbed surface, effectively reducing the ground temperature below the foundation. However, in summer, the ventilation ducts also become channels for hot air circulation, which is very detrimental to protecting the frozen soil. Even with the installation of temperature-controlled dampers, if the roadbed orientation aligns with the prevailing wind direction, the airflow velocity in the ducts is extremely low, making it difficult to achieve a cooling effect.

[0006] (3) Heat pipe roadbed A heat pipe is a passive cooling device that utilizes a low-boiling-point working fluid within its cavity to carry away heat from an evaporation section buried in the roadbed, while a condensation section exposed to the air transfers the heat to the atmosphere, achieving unidirectional heat conduction and lowering the temperature of the frozen soil roadbed. However, the effectiveness of heat pipes is affected by many factors, especially the length of the freezing period. If the freezing period is short and the thawing period is long, and the frozen core has not completely melted before the next winter, then the heat pipe loses its application value. In particular, heat pipes are linear, strong cold sources, which easily lead to temperature inhomogeneity around them, causing a large accumulation of ice water and creating new roadbed defects.

[0007] (4) Diffuse ventilation duct foundation Similar to this technology, both are cooling methods that use forced ventilation duct systems to input cold energy to reduce the roadbed temperature. However, they have the following problems: they cannot reverse the airflow, resulting in the roadbed temperature on the air intake side being significantly lower than that on the air outlet side, thus creating an artificial asymmetric thermal effect; and they cannot verify the input cold energy, which can easily lead to insufficient or excessive cold energy input.

[0008] (5) Insulated board roadbed Insulated subgrade is a passive method of protecting permafrost by using thermal insulation materials embedded within the subgrade, leveraging their high thermal resistance to reduce the entry of atmospheric and anthropogenic heat sources into the permafrost layer. Adding industrial insulation materials to the subgrade increases its thermal resistance without significantly increasing its height, greatly reducing the heat transferred to the soil beneath the insulation layer. This reduces the maximum seasonal thawing depth under the embankment by 1-2 meters, significantly raising the anthropogenic upper limit of permafrost subgrades and contributing to the stability of subgrades in cold regions. However, the positive effect of the insulation layer in reducing heat absorption in the subgrade is not continuous throughout the year. It only exerts its positive effect during the warm season when the outside temperature is higher than the subgrade temperature, causing the temperature gradient to rise. In the cold season, it may even have a negative effect. In other words, this measure is highly time-sensitive in permafrost regions.

[0009] (6) Sunshade board roadbed A sunshade subgrade consists of a layer of panels erected on the slopes and sloping rocks of the subgrade to block and reflect the heat from sunlight, preventing the subgrade temperature from rising. Sunshades effectively prevent heat buildup in the surrounding soil, thus protecting the foundation soil from freezing. However, in winter, due to weaker solar radiation, the heat insulation effect of sunshades is not significant; furthermore, due to the drastic influence of the natural surface, the cooling effect of sunshades at the toe of the subgrade slope is extremely minimal.

[0010] Meanwhile, the presence of surface water and groundwater leads to water accumulation on highways, and the uneven slope effect caused by the road's orientation also contributes to highway damage.

[0011] For the former, the main current solution is to construct a drainage system, but this is ineffective in situations where the soil is frozen in winter or the moisture content is not yet saturated. The main solution to the problem of slopes with varying elevations is a single-sided heat pipe system, the problems of which have already been described above.

[0012] In summary, existing methods for preventing and controlling permafrost subgrade diseases mainly involve cooling measures, without humidity control measures. Furthermore, these methods are essentially one-time designs and constructions without subsequent verification, evaluation, and control mechanisms, making it impossible to achieve precise and intelligent temperature and humidity control. Summary of the Invention

[0013] Based on the addition of a ventilation system to the frozen soil roadbed, this invention proposes an adaptive intelligent ventilation, temperature control and dehumidification system and control method for frozen soil roadbed by constructing a collaborative optimization system of "annual cooling capacity total account + unit cooling capacity allocation + dynamic fan control" to achieve continuous improvement and cyclical enhancement.

[0014] Based on the above concepts, the present invention proposes the following technical solutions: On one hand, this invention provides an adaptive intelligent ventilation, temperature control, and dehumidification system for frozen soil roadbeds, including a temperature sensor, a humidity sensor, a processor, a fan, and a ventilation duct network. The temperature sensor is used to collect the dry bulb temperature at the inlet and outlet of the air duct; The humidity sensor is used to collect the moisture content at the inlet and outlet of the air duct; The processor is used to execute an adaptive intelligent ventilation, temperature control, and dehumidification regulation method for frozen soil subgrade, obtain the upper limit deviation of frozen soil, and adjust the regulation target according to the upper limit deviation of frozen soil. A fan is used to input air into the duct based on the input cooling capacity and the dehumidification capacity calculated by the processor; The ventilation duct network adopts a two-wing diagonal ventilation duct network structure, which is arranged along the highway and set between the active layer and the roadbed fill layer. It is used for air input or output, and the ventilation duct is a semi-rigid, multi-layer composite structure. The method includes the following steps: The enthalpy values ​​at the inlet and outlet of the ventilation duct are calculated based on the dry-bulb temperature and moisture content at the inlet and outlet of the duct. The cooling power is calculated based on the enthalpy value at the inlet of the ventilation duct, the enthalpy value at the outlet of the ventilation duct, and the dry air mass flow rate. The input cooling capacity is calculated by integrating the cooling power over a period of time. The dehumidification capacity is calculated based on the moisture content and dry air mass flow rate. Air is input into the duct according to the input cooling capacity and the input dehumidification capacity; The temperature at different depths of the roadbed was measured to determine the depth value of 0℃ at different times; The difference between the depth value at 0℃ and the depth value at 0℃ set in the control target is used to obtain the upper limit deviation of the frozen soil. If the upper limit deviation of the frozen soil exceeds the preset threshold, the input cold energy is adjusted, and the control target is adjusted, including the annual target and monthly target of the input cold energy.

[0015] On the other hand, based on the same concept, this invention also proposes an adaptive intelligent ventilation, temperature control, and dehumidification regulation method for frozen soil roadbeds, comprising the following steps: The enthalpy values ​​at the inlet and outlet of the ventilation duct are calculated based on the dry-bulb temperature and moisture content at the inlet and outlet of the duct. The cooling power is calculated based on the enthalpy value at the inlet of the ventilation duct, the enthalpy value at the outlet of the ventilation duct, and the dry air mass flow rate. The input cooling capacity is calculated by integrating the cooling power over a period of time. The dehumidification capacity is calculated based on the moisture content and dry air mass flow rate. Air is input into the duct according to the input cooling capacity and the input dehumidification capacity; The temperature at different depths of the roadbed was measured to determine the depth value of 0℃ at different times; The difference between the depth value at 0℃ and the depth value at 0℃ set in the control target is used to obtain the upper limit deviation of the frozen soil. If the upper limit deviation of the frozen soil exceeds the preset threshold, the input cold energy is adjusted, and the control target is adjusted, including the annual target and monthly target of the input cold energy.

[0016] Furthermore, the formula for calculating the cooling power is as follows: ; in, It is dry air mass flow rate; and These are the enthalpy values ​​at the inlet and outlet of the ventilation duct, respectively. It refers to the cooling power.

[0017] Furthermore, the formula for calculating enthalpy is: ; Where h represents the enthalpy value, t is the dry-bulb temperature.

[0018] Furthermore, the formula for calculating the moisture content is: ; ; in, It is the moisture content; This is the partial pressure of water vapor; It is the saturated water vapor pressure; It is the total atmospheric pressure; It refers to relative humidity.

[0019] Furthermore, the dehumidification capacity calculation method involves integrating the first dehumidification capacity over a period of time, and the formula for calculating the first dehumidification capacity is: ; in, It is the first dehumidification capacity. It is dry air mass flow rate. This refers to the dehumidification capacity at the duct inlet. It is the dehumidification capacity of the air duct outlet.

[0020] Furthermore, the annual targets for adjusting cooling capacity include: The annual comparison difference is obtained by subtracting the depth value at 0℃ in the previous year from the preset annual depth value at 0℃. If the annual comparison difference exceeds 0.5m, the cooling capacity input value for the following year will be adjusted accordingly, with an adjustment range of ±2%. If the annual comparison difference exceeds 1m, the cooling input value for the following year will be adjusted accordingly, with an adjustment range of ±5%. Otherwise, the cooling input value of the previous year will be used as the cooling input value of the next year.

[0021] Furthermore, the monthly targets for adjusting cooling capacity include: The monthly comparison difference is obtained by subtracting the monthly depth value at 0℃ from the preset monthly depth value at 0℃. If the monthly comparison difference exceeds 0.5m, the cooling input value for the next month will be adjusted by ±5%.

[0022] Furthermore, it also includes regulating the moisture content within the ductwork by ventilating the ducts. Ventilation conditions include: The temperature inside the duct has reached the expected value, but the moisture content inside the duct exceeds the standard and accumulates. and, The subgrade soil temperature is above 5℃ and the ambient temperature is not higher than the average temperature of the subgrade soil, and the relative humidity of the air is <60%.

[0023] Furthermore, it also includes methods for determining and compensating for outstanding cooling loads: The difference between the required cooling capacity and the input cooling capacity value is calculated to obtain the cooling capacity difference value. If the cooling capacity difference value is greater than or equal to the cooling capacity threshold, the compensation method is triggered. The specific methods for triggering compensation include: the planned cooling capacity for the next day = the baseline for the current day + the difference in cooling capacity, and the planned cooling capacity for the next day is achieved by extending the ventilation time of the input cooling air; the planned cooling capacity for the current day is used as the baseline for the current day, and the cooling capacity deficit is the cooling capacity deficit.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows: The present invention establishes a numerical model of annual-daily dual-cycle ground-atmosphere coupled heat exchange for permafrost roadbeds on the Qinghai-Tibet Plateau, in order to determine the human upper limit control target for protecting permafrost (the human upper limit is not lower than the natural upper limit). Based on the calculated control target and relevant data of the Qinghai-Tibet Plateau engineering corridor, the design reference for temperature control, dehumidification, and cold energy input under different permafrost occurrence conditions and climatic environment conditions is determined. Attached Figure Description

[0025] Figure 1 This is a flowchart of the operation of the present invention; Figure 2This is a curve diagram of the artificial upper limit control target of the present invention; Figure 3 This is the heat control measure of the present invention; Figure 4 This is a roadbed structure diagram of the present invention; Figure 5 This is a schematic diagram of the ventilation duct layout of the present invention; Figure 6 This is a three-dimensional layout diagram of the ventilation duct of the present invention; Figure 7 This is a layout diagram of the temperature measuring device of the present invention; Figure 8 This is a schematic diagram of the ventilation system of the present invention.

[0026] The diagram is marked as follows: 1-Gravelly clay layer, 2-Silty clay layer, 3-Active layer, 4-Subgrade fill layer, 5-Semi-rigid base layer, 6-Asphalt pavement layer, 7-Symmetrical ventilation pipe with two wings, 8-Air inlet, 9-Air outlet, 10-Shoulder, 11-Slope protection, 12-Temperature sensor, 13-Temperature and humidity sensor, 14-Upper limit of frozen soil, 15-Natural surface, 16-Temperature measuring cable. Detailed Implementation

[0027] To facilitate understanding of the present invention, a more complete description will be given below with reference to the accompanying drawings. Preferred embodiments of the invention are shown in the drawings. However, the invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the invention.

[0028] In the description of this invention, it should be understood that the terms "upper", "lower", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0029] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the term "set up" and the like should be interpreted broadly. For example, it can mean fixedly connected, detachably connected, or integrally connected. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0030] Furthermore, in the description of this invention, the terms "first," "second," etc., are used only for distinguishing descriptions and should not be construed as indicating or implying relative importance. Of course, such terms can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in a sequence other than those illustrated or described herein.

[0031] It should also be noted that although the order of steps is mentioned in the method description, in some cases, steps may be performed in a different order than that described here, and this should not be interpreted as a restriction on the order of steps.

[0032] This invention proposes an adaptive intelligent ventilation, temperature control, and dehumidification system and control method for frozen soil roadbeds. For example... Figure 1 The flowchart of the regulation method described in this invention establishes a rapid calculation system for roadbed thermal conditions based on a numerical model of land-atmosphere coupled heat transfer on the Tibetan Plateau, setting dual regulation targets for both interannual and intra-annual periods. The interannual target is based on the assumption that the upper limit of anthropogenic permafrost within a 20-year cycle is close to the natural upper limit. The intra-annual target is achieved through the dynamic coupling of temperature difference and cooling hours. The optimized allocation of cooling capacity is determined through a modular design to establish a cooling input parameter system for permafrost zones in different climate zones.

[0033] Example 1 An adaptive intelligent ventilation, temperature control, and dehumidification regulation method for frozen soil roadbeds, the flowchart of which is as follows: Figure 1 As shown, it includes the following steps: The enthalpy values ​​at the inlet and outlet of the duct are calculated based on the dry-bulb temperature and moisture content at the inlet and outlet of the duct. The cooling power is calculated based on the enthalpy value at the duct inlet, the enthalpy value at the duct outlet, and the dry air mass flow rate. The input cooling capacity is calculated by integrating the cooling power over a period of time. The dehumidification capacity is calculated based on the moisture content and dry air mass flow rate. Air is input into the duct according to the input cooling capacity and the input dehumidification capacity; The temperature at different depths of the roadbed was measured to determine the depth value of 0℃ at different times; The difference between the depth value at 0℃ and the depth value at 0℃ set in the control target is used to obtain the upper limit deviation of the frozen soil. If the upper limit deviation of the frozen soil exceeds the preset threshold, the input cold energy is adjusted, and the control target is adjusted, including the annual target and monthly target of the input cold energy.

[0034] To determine the subsequent input cooling capacity, this invention installs a high-precision air temperature and humidity sensor at both the duct inlet and outlet to measure and calculate the expected cooling capacity and dehumidification capacity removed. 1. Parameter Measurement (1) Measurement parameters: Inlet and outlet dry bulb temperatures ( , (unit: °C) and relative humidity ( , ,unit:%).

[0035] (2) Auxiliary parameters: atmospheric pressure (Pa, usually taken as standard atmospheric pressure 101325Pa) and duct volume flow rate (Q, unit: m³ / s).

[0036] 2. Moisture content calculation: The formula for calculating moisture content is derived from the equation of state for an ideal gas mixture, which is widely used in fields such as engineering thermodynamics and HVAC.

[0037] ; ; in, It is the moisture content, in g / kg; This is the partial pressure of water vapor, Pa; It is the saturated water vapor pressure, Pa; It is the total atmospheric pressure; It refers to relative humidity.

[0038] 3. Enthalpy calculation: Calculate the enthalpy values ​​at the inlet and outlet respectively. and The formula for calculating the enthalpy of moist air is:

[0039] Enthalpy value, kJ / kg; d is the dry-bulb temperature, and d is the moisture content.

[0040] The formula for calculating the enthalpy of moist air represents the total energy of moist air (sensible heat + latent heat), and is commonly used in thermodynamic analysis, air conditioning systems, and drying processes. This formula can be divided into two parts: This indicates that dry air is heated from 0°C to a certain temperature. The required calories.

[0041] It represents the total enthalpy (including heat of phase change and sensible heat) of water vapor contained in a unit mass of dry air.

[0042] The calculation formula for cooling power is derived from the law of conservation of energy for moist air. It is an energy analysis tool for the "air handling process" in HVAC and refrigeration engineering. Its core logic is that "the enthalpy difference of a change in the state of moist air corresponds to the power of energy transfer." Based on the principle of energy conservation, the cooling process involves moist air releasing heat (enthalpy decrease) as it passes through the equipment. The cooling power of the equipment is equal to the decrease in enthalpy of the moist air per unit time. Therefore:

[0043]

[0044]

[0045] Cooling power, kW; Dry air mass flow rate, kg / s; Dry air density, kg / m3; : Gas constant for dry air; Enthalpy of imported air; Enthalpy of air at the outlet; Volumetric flow rate, m³ / s; T: Absolute temperature, K; Water vapor partial pressure; Total pressure of moist air.

[0046] These three equations together describe the process of calculating the cooling power achieved through airflow: 1. Calculate the dry air density 2. Calculate the dry air mass flow rate. 3. Calculate the cooling power .

[0047] 5. Input cooling capacity calculation The input cooling capacity is the integral of the cooling power over time:

[0048] Total cooling capacity, kJ; t is the cooling power; t is time.

[0049] 6. Dehumidification capacity calculation Dehumidification capacity is calculated by multiplying the difference in moisture content by the dry air mass flow rate. ; in, This refers to the dehumidification capacity at the duct inlet. This refers to the dehumidification capacity at the duct outlet. It is dry air mass flow rate. This refers to the dehumidification capacity.

[0050] Total dehumidification capacity is the integral of dehumidification capacity over time: ; This invention focuses on precise temperature control while also considering effective dehumidification of the roadbed. It emphasizes the basic control concept of "human intervention in the loop" to achieve the "flat and stable" upper limit of human intervention for frozen soil roadbeds. "Flat" refers to the uniformity of the temperature field in space, and "stable" refers to the stability of the upper limit of human intervention over time. At the same time, it aims to reduce the effects of water and ice accumulation in the roadbed by achieving the goal of temperature control and dehumidification.

[0051] To avoid relying solely on weather conditions and to realize the fundamental control concept of "human intervention in the loop," this invention continuously monitors, verifies, and adjusts the system. ①Annual verification: Based on the temperature monitoring data of boreholes on both sides of the road, the middle of the road and the natural surface, determine the upper limit of permafrost in each location to verify whether the target has been achieved in the previous year; ② Annual verification: Based on the temperature monitoring data of boreholes on both sides of the road, the middle of the road, and the natural surface, predict whether the corresponding control targets can be achieved and make adjustments in advance; ③ Use moisture sensors embedded in the roadbed to monitor the moisture content of the roadbed and determine whether the dehumidification effect has achieved the target.

[0052] This monitoring, verification, and adjustment system employs adaptive learning control technology, implemented through automated control software. After several years of operation and the accumulation of substantial data, it should be able to achieve machine learning and adaptive adjustment. Based on the predicted upper limit of frozen soil output from the model, a PID control algorithm for the ventilation system is designed to achieve adaptive adjustment of temperature boundary conditions, thereby ensuring the frozen soil subgrade remains stable and at the upper limit set by human intervention.

[0053] This invention uses a specific engineering project as a case study to illustrate the process. The designed separated roadbed pavement has a width of 13.25m and a standard roadbed height of 3m. I. System Initialization Preset parameters are read: upper limit of natural permafrost 2.5m, daily predetermined cooling capacity 36kJ / m², which serves as the daily benchmark for calculating the predetermined cooling capacity for the following day. The initial estimated period for conduction of cooling capacity is 0:00-8:00 on the same day (ambient temperature is more than 5℃ lower than the roadbed temperature). Historical temperature data for the same period are loaded into the LSTM model (average low temperature period is 7-8 hours).

[0054] II. Real-time Data Monitoring (Monthly Monitoring Data) Soil temperature field: The temperature of the underlying frozen soil at the center of the roadbed measured by the shoulder temperature sensor is -1.0℃, and the temperature of the active layer is 6℃.

[0055] Duct temperature and humidity: Inlet dry bulb temperature -5℃, relative humidity 50%; outlet dry bulb temperature 2℃, relative humidity 80%.

[0056] Actual ventilation time: 0:00-5:00, a total of 5 hours (originally planned for 8 hours), but the number of hours that can conduct cooling was reduced by 3 hours due to the increase in temperature.

[0057] III. Calculate the input cooling capacity and dehumidification capacity. Calculate according to the formula (Unit: g / kg); ; in, It is the moisture content; It is the partial pressure of water vapor; The partial pressure of saturated water vapor. It is the total atmospheric pressure; It refers to relative humidity; Therefore, the calculation shows that: Imported moisture content: =1.66g / kg; Export moisture content: =4.24g / kg; Dehumidification capacity: d2-d1=2.58g / kg; (Default is 1 kg / s) Enthalpy h (kJ / kg) is the sum of sensible heat and latent heat (simplified calculation: take the inlet enthalpy). =-2kJ / kg, enthalpy at the outlet =10kJ / kg, the difference is derived based on temperature and humidity): =12kJ / kg; Cooling power: =0.144kW; Calculate the actual input cooling capacity ( Based on the fundamental conversion relationship between energy and power: =

[0058] (t is the ventilation duration, in seconds); Actual cooling input; Cooling capacity; t: Ventilation duration, unit: seconds.

[0059] t = 8 hours = 28800 seconds; =24kJ / m 2 Calculate the outstanding amount of cooling capacity ( ): = ; IV. Assessment and Compensation Mechanism for Cold Air Debt Cooling load deficit (12kJ / m²>0) triggers compensation mechanism ("Failure to achieve the target on the day is recorded as cooling load deficit, which will be made up for by increasing cooling load in the future").

[0060] Other indicators were checked simultaneously: the measured upper limit of frozen soil was 2.45m (0.05m difference from the target of 2.5m, which did not exceed the 0.5m threshold); the moisture content was 14% (below the threshold of 15%, which did not exceed the standard).

[0061] To address the shortfall in cooling capacity, the plan is to make up for it the following day during the low-temperature period (estimated 0:00-9:00, temperature difference > 5℃, capable of conducting cooling for 9 hours): the planned cooling capacity for the next day = the daily baseline of 36kJ / m² + the shortfall of 12kJ / m² = 48kJ / m², which will be made up by extending ventilation by 1 hour (total 9 hours).

[0062] V. Upper Limit Control and Temperature and Humidity Control According to the upper limit control target, such as Figure 2 As shown, dual regulation will be implemented both intra-year and inter-year. Specific regulation targets and cooling capacity allocation are as follows: Figure 2 and Figure 3 As shown. Figure 2 It is a target curve chart with an artificially set upper limit. The upper limit of this chart is used as a basis for judgment, thereby providing better data support for this system. Figure 3 It is a heat control measure.

[0063] Annual control: Temperature measuring cables are laid in the center hole of the roadbed, with a temperature measuring point set every 0.5m. The deepest temperature measuring point is located 2m below the natural upper limit of the frozen soil. The ground temperature at each point is monitored in real time through the temperature measuring cables. The 0℃ position (i.e. the melting depth at that time) is determined by linear interpolation. The control target is compared with that determined by (1)① once a month. If the difference exceeds 0.5m, the cold input for the following month is adjusted accordingly (the adjustment range is ±5%). Otherwise, the planned cold input is maintained.

[0064] Interannual adjustment: The final adjustment result of the previous year's artificial upper limit is compared with the natural upper limit. If the difference exceeds 0.5m, the cooling input value for the next year is adjusted accordingly (adjustment range is ±2%). 0.5m is the first judgment threshold; if the difference is greater than 0.5m, the cooling input is increased by 2%, and if the difference is less than 0.5m, the cooling input is decreased by 2%. If the difference exceeds 1m, the adjustment range is ±5%, that is, 1m is the second judgment threshold; if the difference is greater than 1m, the cooling input is increased by 2%, and if the difference is less than 1m, the cooling input is decreased by 2%. Otherwise, the cooling input allocation scheme of the previous year is used as the input scheme for the next year.

[0065] Temperature and humidity control Moisture regulation within the road: If moisture concentration does occur, the timing of air intake can be adjusted by judging the air moisture content, that is, ventilation should be given more consideration when the air is dry. If the road surface temperature has reached the expected value, but the moisture content is excessive or even accumulates, the timing of the ventilation fan input can be adjusted. During the warm season (when the roadbed soil temperature is above 5°C), when the ambient temperature is not higher than the average temperature of the roadbed soil but the relative humidity is low (<60%), ventilation can be carried out to remove more moisture from the roadbed soil.

[0066] Temperature uniformity: The main concern is the attenuation of cooling and dehumidification effect of airflow along the pipe length. It is proposed to improve this by adjusting the airflow speed.

[0067] VI. Duct Structure Design Roadbed structure diagram as follows Figure 4 As shown, Figure 4 The bottom layer is a gravelly clay layer 1, followed by a silty clay layer 2, an active layer 3, and then a subgrade fill layer 4 on top of the active layer 3. Above the subgrade fill layer 4, a semi-rigid base course 5 and an asphalt pavement layer 6 are laid out. Ventilation ducts are installed on the subgrade structure, as shown in the schematic diagram below. Figure 5 As shown in the diagram, the three-dimensional layout of the ventilation ducts is as follows: Figure 6 As shown, the hardware architecture of the ventilation system includes a two-wing symmetrical ventilation duct network layout 7. Using CFD design methods and engineering practice verification, a three-dimensional numerical simulation model of the ventilation duct subgrade considering convective heat transfer boundary conditions was constructed. Wind speed correction was implemented for the airflow parameters of ventilation systems with different pipe diameters. By comparing and analyzing the control stability index and operational economic parameters of the ventilation system under multiple operating conditions, the engineering applicability of different pipe diameter schemes was systematically evaluated. Finally, an optimal parameter matching scheme balancing technical performance and economic indicators was established: the ventilation system adopts a two-wing diagonal ventilation duct network architecture, with one ventilation system arranged every 20m along the highway direction, and a ventilation duct spacing of 2m. The 0.12m pipe diameter ventilation system was ultimately determined as the ideal ventilation system for a 3m high mechanical ventilation duct subgrade. Two-wing symmetrical ventilation ducts 7 are installed between the air inlet 8, air outlet 9, active layer 3, and subgrade fill layer 4. The two-wing symmetrical ventilation duct 7 is a semi-rigid, multi-layered composite structure, consisting of the following components from the inside out: Inner lining (corrosion-resistant, flow-guiding layer): Materials: Polytetrafluoroethylene (PTFE) coated fiber cloth, stainless steel wire mesh support layer (strength layer); Materials: 316L stainless steel (low temperature resistant, corrosion resistant) woven wire mesh, breathable fiber woven layer (breathable temperature control layer); Materials: Composite fiber woven fabric (must meet requirements for moisture permeability, frost resistance, and weather resistance), outer protective layer (weather-resistant and anti-aging layer); Materials: Coating: Polyvinyl chloride (PVC); Additional protection: puncture-resistant nonwoven fabric (such as polypropylene PP nonwoven fabric).

[0068] VII. Sensor and Cable Arrangement Figure 7 For the arrangement of various sensors, temperature sensors 12 are horizontally deployed in the movable layer 3 below the symmetrical ventilation ducts 7 on both sides. Temperature sensors 12 are deployed within the area of ​​the road shoulder 10 and the road surface area between the two road shoulders 10. Based on the on-site route direction and roadbed morphology, a ventilation monitoring unit is set up approximately every 1000m. The road shoulders 10 are flanked by slope protection 11. Along the direction of the ventilation duct, sensors are embedded in the roadbed soil at the inlet, middle, and outlet sides, respectively. The average value is taken as the average soil temperature. Ventilation begins when the ambient temperature (ventilation duct inlet temperature) is lower than the average soil temperature; otherwise, the fan is shut down.

[0069] Ventilation begins when the ambient temperature is more than 5°C below the interior temperature of the roadbed. The fans are turned off once the predetermined cooling capacity is achieved each day. If the target cooling capacity is not achieved on a given day, it is recorded as a cooling capacity deficit, which will be made up for later by increasing the cooling capacity.

[0070] Temperature and humidity sensors 13 are arranged in the air inlet 8 and air outlet 9 to measure the temperature and humidity of the air at the inlet and outlet, thereby calculating the sensible heat and latent heat removed. The sum of the two is the cooling capacity, i.e., the enthalpy difference between the inlet and outlet humid air, and the dehumidification capacity is also calculated. If it is found that the temperature inside the road has reached the expected value, but the moisture content inside the road exceeds the standard or even accumulates, the timing of the fan input can be adjusted. That is, ventilation can be carried out during the warm season (when the temperature of the roadbed soil is higher than 5°C) when the ambient temperature is not higher than the average temperature of the roadbed soil but the relative humidity is low (<60%), so as to achieve the purpose of ventilation removing more moisture from the roadbed soil.

[0071] Temperature measuring cables 16 are laid in the center hole of the roadbed, with a temperature measuring point set every 0.5m. The natural ground surface 15, the upper limit of the frozen soil 14, and the temperature measuring cables 16 are marked sequentially. The deepest temperature measuring point on the natural ground surface is arranged 2m below the upper limit of the frozen soil 14. The ground temperature at each point is monitored in real time through the temperature measuring cables 16. The 0℃ position (i.e., the thawing depth at that moment) is determined by linear interpolation, thereby adjusting the cold input of the system.

[0072] The above methods facilitate continuous monitoring, verification, and adjustment of the system, embodying the "human-in-the-loop" concept.

[0073] Figure 8To address this, a schematic diagram of a ventilation system was invented, illustrating the core architecture and operational logic of an intelligent temperature control and dehumidification ventilation system for permafrost subgrades. The system, centered on an intelligent monitoring platform, integrates a pipeline wind speed and temperature monitoring module, a subgrade temperature field, multi-location temperature sensors on the foundation, and a human-controlled upper limit for stability. Dynamic cooling capacity adjustment is achieved through the linkage of reversible variable frequency fans and coolers. Its operation is driven by wind speed and direction data; ventilation is activated when the ambient temperature falls below the subgrade temperature threshold. Cooling capacity input is precisely controlled through comprehensive calculation of sensible and latent heat. The intelligent monitoring system, relying on machine learning algorithms, performs real-time analysis of remotely collected soil temperature gradient and humidity data, optimizing fan start-up and shutdown strategies and cooling capacity distribution schemes to ensure a balanced transverse temperature field (temperature difference <0.5℃) and stable longitudinal permafrost upper limit for the subgrade. Through a closed-loop control system of "monitoring-calculation-execution-feedback," the system achieves coordinated operation of the ventilation network (including a wind speed correction module), cooling devices, and foundation thermal stability, ultimately achieving full-section thermal balance and moisture migration control in the permafrost subgrade. The system is equipped with an adaptive learning module, which uses an LSTM neural network to train on historical data and continuously optimize the cooling allocation strategy.

[0074] Compared with traditional control methods, the advantages of the control method of this invention are shown in Table 1.

[0075] Table 1. Comparison of the control method of this invention and the traditional control method.

[0076] This invention provides an intelligent ventilation control system and method for frozen soil subgrade with closed-loop regulation of annual cooling supply. Based on the addition of a ventilation system to the frozen soil subgrade, it achieves a leapfrog innovation in temperature control and dehumidification technology by constructing a collaborative optimization system of "annual cooling supply ledger + unit cooling supply allocation + dynamic fan control". This temperature control, dehumidification, and ventilation system and method for frozen soil subgrade utilizes the PDCA (Deming cycle) concept from management science to achieve continuous improvement and cyclical enhancement. This invention establishes a numerical model for annual-daily dual-cycle ground-atmosphere coupled heat exchange in permafrost roadbeds on the Qinghai-Tibet Plateau, to determine the human-controlled upper limit for permafrost protection (with an anthropogenic upper limit not lower than the natural upper limit): Based on the calculated control targets and relevant data from the Qinghai-Tibet Plateau engineering corridor, a modular design reference for the temperature control and dehumidification interface cold input is determined under different permafrost conditions and climatic environments.

[0077] Finally, it should be noted that the embodiments described in the above description are merely preferred practices of the invention and should not be construed as limiting the scope of the invention. Equivalent substitutions for the technical solutions described in the foregoing embodiments do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the invention, and all such substitutions should be covered within the scope of the claims and specification of the invention.

Claims

1. An adaptive intelligent ventilation, temperature control, and dehumidification system for frozen soil roadbeds, characterized in that, Includes temperature sensors, humidity sensors, processors, fans, and ventilation ductwork. The temperature sensor is used to collect the dry bulb temperature at the inlet and outlet of the air duct; The humidity sensor is used to collect the moisture content at the inlet and outlet of the air duct; The processor is used to execute an adaptive intelligent ventilation, temperature control, and dehumidification regulation method for frozen soil subgrade, obtain the upper limit deviation of frozen soil, and adjust the regulation target according to the upper limit deviation of frozen soil. A fan is used to input air into the duct based on the input cooling capacity and the dehumidification capacity calculated by the processor; The ventilation duct network adopts a two-wing diagonal ventilation duct network structure, which is arranged along the highway and set between the active layer and the roadbed fill layer. It is used for air input or output, and the ventilation duct is a semi-rigid, multi-layer composite structure. The method includes the following steps: The enthalpy values ​​at the inlet and outlet of the ventilation duct are calculated based on the dry-bulb temperature and moisture content at the inlet and outlet of the duct. The cooling power is calculated based on the enthalpy value at the inlet of the ventilation duct, the enthalpy value at the outlet of the ventilation duct, and the dry air mass flow rate. The input cooling capacity is calculated by integrating the cooling power over a period of time. The dehumidification capacity is calculated based on the moisture content and dry air mass flow rate. Air is input into the duct according to the input cooling capacity and the input dehumidification capacity; The temperature at different depths of the roadbed was measured to determine the depth value of 0℃ at different times; The difference between the depth value at 0℃ and the depth value at 0℃ set in the control target is used to obtain the upper limit deviation of the frozen soil. If the upper limit deviation of the frozen soil exceeds the preset threshold, the input cold energy is adjusted, and the control target is adjusted, including the annual target and monthly target of the input cold energy.

2. An adaptive intelligent ventilation, temperature control, and dehumidification regulation method for frozen soil roadbeds, characterized in that, Includes the following steps: The enthalpy values ​​at the inlet and outlet of the ventilation duct are calculated based on the dry-bulb temperature and moisture content at the inlet and outlet of the duct. The cooling power is calculated based on the enthalpy value at the inlet of the ventilation duct, the enthalpy value at the outlet of the ventilation duct, and the dry air mass flow rate. The input cooling capacity is calculated by integrating the cooling power over a period of time. The dehumidification capacity is calculated based on the moisture content and dry air mass flow rate. Air is input into the duct according to the input cooling capacity and the input dehumidification capacity; The temperature at different depths of the roadbed was measured to determine the depth value of 0℃ at different times; The difference between the depth value at 0℃ and the depth value at 0℃ set in the control target is used to obtain the upper limit deviation of the frozen soil. If the upper limit deviation of the frozen soil exceeds the preset threshold, the input cold energy is adjusted, and the control target is adjusted, including the annual target and monthly target of the input cold energy.

3. The adaptive intelligent ventilation, temperature control, and dehumidification regulation method for frozen soil roadbed as described in claim 2, characterized in that, The formula for calculating the cooling power is: ； in, It is dry air mass flow rate; and These are the enthalpy values ​​at the inlet and outlet of the ventilation duct, respectively. It refers to the cooling power.

4. The adaptive intelligent ventilation, temperature control, and dehumidification regulation method for frozen soil roadbed as described in claim 2, characterized in that, The formula for calculating enthalpy is: ； Where h represents the enthalpy value, t is the dry-bulb temperature.

5. The adaptive intelligent ventilation, temperature control, and dehumidification regulation method for frozen soil roadbed as described in claim 2, characterized in that, The formula for calculating the moisture content is: ； ； in, It is the moisture content; This is the partial pressure of water vapor; It is the saturated water vapor pressure; It is the total atmospheric pressure; It refers to relative humidity.

6. The adaptive intelligent ventilation, temperature control, and dehumidification regulation method for frozen soil roadbed as described in claim 2, characterized in that, The dehumidification capacity is calculated by integrating the first dehumidification capacity over a period of time. The formula for calculating the first dehumidification capacity is as follows: ； in, It is the first dehumidification capacity. It is dry air mass flow rate. This refers to the dehumidification capacity at the duct inlet. It is the dehumidification capacity of the air duct outlet.

7. The adaptive intelligent ventilation, temperature control, and dehumidification regulation method for frozen soil roadbed as described in claim 2, characterized in that, The annual targets for adjusting cooling capacity include: The annual comparison difference is obtained by subtracting the depth value at 0℃ in the previous year from the preset annual depth value at 0℃. If the annual comparison difference exceeds 0.5m, the cooling capacity input value for the following year will be adjusted accordingly, with an adjustment range of ±2%. If the annual comparison difference exceeds 1m, the cooling input value for the following year will be adjusted accordingly, with an adjustment range of ±5%. Otherwise, the cooling input value of the previous year will be used as the cooling input value of the next year.

8. The adaptive intelligent ventilation, temperature control, and dehumidification regulation method for frozen soil roadbed as described in claim 2, characterized in that, The monthly targets for adjusting cooling capacity include: The monthly comparison difference is obtained by subtracting the monthly depth value at 0℃ from the preset monthly depth value at 0℃. If the monthly comparison difference exceeds 0.5m, the cooling input value for the next month will be adjusted by ±5%.

9. An adaptive intelligent ventilation, temperature control, and dehumidification regulation method for frozen soil roadbeds as described in any one of claims 2-8, characterized in that, This also includes regulating moisture within the ductwork by ventilating the ducts. Ventilation conditions include: The temperature inside the duct has reached the expected value, but the moisture content inside the duct exceeds the standard and accumulates. and, The subgrade soil temperature is above 5℃ and the ambient temperature is not higher than the average temperature of the subgrade soil, and the relative humidity of the air is <60%.

10. An adaptive intelligent ventilation, temperature control, and dehumidification regulation method for frozen soil roadbeds as described in any one of claims 2-8, characterized in that, It also includes methods for determining and compensating for outstanding cooling loads: The difference between the required cooling capacity and the input cooling capacity value is calculated to obtain the cooling capacity difference value. If the cooling capacity difference value is greater than or equal to the cooling capacity threshold, the compensation method is triggered. The specific methods for triggering compensation include: the planned cooling capacity for the next day = the baseline for the current day + the difference in cooling capacity, which is achieved by extending the ventilation time of the input cooling air to reach the planned cooling capacity for the next day; The daily pre-set cooling capacity is used as the benchmark for that day, and any shortfall in cooling capacity is considered a shortfall in cooling capacity.

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