Railway roadbed frost heaving disease prevention and control system and method adapting to severe cold climate

Abstract

The invention discloses a railway roadbed frost heaving disease prevention and control system and method adapting to severe cold climate, and belongs to the technical field of seasonal frozen soil engineering.The prevention and control system comprises a plurality of ground source heat pump devices composed of heating units, heat supply pipes, heat collection pipes and detection assemblies, and the heating units are arranged at the slope toe position of a roadbed in the length direction of a railway; the heat supply pipe is laid on a frost heaving development layer of a roadbed, the heat collecting pipes are arranged on stable layers of the roadbed on the two sides of the roadbed, and the heat-carrying agent circularly flows in a pipeline composed of the heat supply pipe, the heating unit and the heat collecting pipes. A temperature sensor, a pressure sensor and a displacement sensor are used for monitoring the roadbed freezing temperature, the heat-carrying agent temperature, the suction and exhaust pressure of a compressor and the deformation amount of a track; and the control assembly receives a signal of the detection assembly and controls the operation mode of the heating unit. According to the method, rapid establishment of the superheat degree of the compressor in the starting stage in the severe cold environment and reasonable control over the exhaust temperature range and the operation mode of the compressor in the normal operation stage can be guaranteed.

Description

Technical Field

[0001] The present invention belongs to the technical field of seasonal frozen soil engineering, and particularly relates to a prevention and control system and method for frost heaving diseases of railway subgrades adapted to severe cold climates. Background Technique

[0002] Frozen soil accounts for more than 70% of China's land area, and the proportion of deep seasonal frozen soil with a freezing depth greater than 1.5 m is about 37%. The areas where it is located are mostly severe cold climate regions. Different from the thaw settlement problems faced by the operation of railways in permafrost regions, the main problem faced by the operation of railways in deep seasonal frozen soil regions is the frost heaving diseases of subgrades in some sections in winter. This is due to the formation of discontinuous water enrichment areas in the subgrade filler under the influence of capillary recharge of local shallow groundwater and precipitation infiltration at individual damaged positions. The freezing and expansion of water will cause uneven frost heaving deformation on the top surface of the subgrade, and then cause the geometric shape of the track to be uneven, endangering the safety of train operation. Conventional prevention and control measures for frost heaving diseases mainly rely on human and physical defenses, including track frost heaving pads, in-situ improvement of subgrades by grouting, replacement of fillers, water prevention and drainage, thermal insulation structures, etc. Their limitation is that the treatment effect is poor and the timeliness is insufficient when facing stubborn and sudden frost heaving, lacking the ability to quickly eliminate frost heaving deformation after it appears, and it is difficult to meet the requirements for treating frost damage at key positions such as transition sections, turnout areas, and curves. For this reason, the railway industry has begun to introduce artificial heating technology to eradicate frost heaving diseases by actively inputting heat and raising the temperature to the frost heaving layer of the subgrade. For example, in the invention patent with the application number CN201820317204.1, a ground source heat pump device for preventing and controlling frost heaving of subgrades in seasonal frozen soil areas is disclosed, which belongs to a heating system that uses geothermal energy as the heat source and a heat pump as the means for heat energy conversion and transmission. In the invention patent with the application number CN202211115741.5, an anti-frost heaving subgrade system and a subgrade heating method are disclosed, which belong to a ground source heat pump system that conducts staged intermittent heating according to the heat load of the subgrade.

[0003] In the above-disclosed patent documents, the heat pump is the key heat energy carrier, and the compressor is the core driving component of the heat pump. Its function is to provide power for the phase change cycle of the heat carrier and the conversion and transmission of heat energy. The heat pump anti-frost heaving system has been successively applied to national trunk railways such as the Qinghai-Tibet Railway, the Lanzhou-Xinjiang Railway, and the Shenyang-Baishan High-Speed Railway in recent years. Railway subgrade frost heaving diseases mostly occur in severe cold climate regions with low environmental temperatures and high frequencies of cold snaps. The instantaneous extreme low temperature in winter can reach about -40°C, and the freezing period lasts from November of each year to April of the following year. The main problems found during the application of the heat pump are as follows: First, from the perspective of heat pump startup, due to the low-temperature environment in winter in the severe cold climate zone, the return gas temperature of the heat carrier at the compressor inlet is too low at the initial stage of heat pump startup, making it difficult to quickly establish a reasonable superheat degree required by the compressor, and the time consumed from startup to normal operation is too long. Second, from the perspective of heat pump operation, due to the low-grade and low-density distribution conditions of geothermal energy in the severe cold climate zone, after the heat pump enters the normal operation state, the heat collection efficiency of geothermal energy will gradually decrease, resulting in a decrease in the gasification rate of the heat carrier in the ground heat collection pipe on the low-pressure side of the heat pump, and the return flow of the heat carrier of the compressor and the flow rate of the heat carrier in the heat supply component on the high-pressure side will decrease accordingly. As a result, adverse consequences such as too high exhaust temperature of the compressor, deterioration of internal lubricating oil and damage of the oil film, and insufficient heating capacity will occur, making it difficult to meet the requirements for preventing subgrade frost heave. When the evaporation pressure of the heat carrier approaches the atmospheric pressure, even negative pressure inside the heat collection component on the low-pressure side and air extraction of the compressor will occur, and the failure damage rate of the compressor will increase sharply. Third, when preventing and controlling subgrade frost heave diseases, the operation control of the heat pump is based on the subgrade temperature and aims to eliminate the frozen state of the subgrade. Blindly increasing the heating capacity requirement causes heat overflow loss in the non-frost heave lesion area, resulting in high energy consumption of the heat pump, imbalance between the use cost and the equipment installation cost, and poor economy.

[0004] In summary, under the extremely cold climate environment, the heat pump widely has limitations such as slow startup speed, short stable operation time, high operation energy consumption, and low long-term life, which limit the practicality of the ground source heat pump technology for the problem of railway subgrade frost heave diseases.

[0005] It can be seen that solving the three problems of low-temperature startup speed, stable operation duration, and operation control energy efficiency of the ground source heat pump system in the severe cold climate environment is the key to improving the practical levels such as timeliness, efficiency, reliability, energy conservation, and economy of the prevention and control effect of railway subgrade frost heave diseases in the severe cold region. Summary of the Invention

[0006] The present invention provides a prevention and control system and method for railway subgrade frost heave diseases suitable for severe cold climates, aiming to solve the technical problems of slow startup speed, short stable operation time, high operation energy consumption, and low long-term life of the compressor, which is the core driving component of the existing ground source heat pump system for railway subgrades, in the severe cold climate environment.

[0007] To achieve the above object, the technical solutions adopted by the present invention are as follows:

[0008] A prevention and control system for railway subgrade frost heave diseases suitable for severe cold climates, the prevention and control system includes a plurality of groups of ground source heat pump devices arranged at intervals along the length direction of the railway subgrade. The ground source heat pump device includes a heating unit, a heat supply pipe, a heat collection pipe, and a detection component. The heat collection pipe is connected to the heat supply pipe through the heating unit. The heating unit is located on the surface of the foundation at the toe of the subgrade slope. The heat supply pipe is horizontally laid in the frost heave development layer of the subgrade and perpendicular to the length direction of the subgrade. The heat collection pipe is vertically located in the lower stable layer of the foundation on both sides of the subgrade.

[0009] The detection component includes a temperature sensor, a pressure sensor, and a displacement sensor. Temperature sensors are provided inside the subgrade, in the middle of the heat collecting pipe, and on the pipeline of the heating unit, respectively for monitoring the harmful freezing temperature of the subgrade and the temperature of the heat carrier in the pipeline; Pressure sensors are provided at the suction port and the discharge port of the compressor of the heating unit for monitoring the suction and discharge pressures of the compressor; The displacement sensor is arranged at the web of the railway track for detecting the deformation of the track. The heating unit, temperature sensor, pressure sensor, and displacement sensor are all connected to the control component.

[0010] Furthermore, the heating unit includes a cabinet and a heating component. The heating component and the control component are both arranged inside the cabinet. The heating component is connected to the heat supply pipe and the heat collecting pipe through pipelines. The heating component can realize the condensation and liquefaction and evaporation and gasification of the heat carrier, respectively for heating the subgrade and absorbing heat from the foundation;

[0011] The heating component includes a compressor, a gas-liquid separator I, a liquid storage tank, a throttler, and a gas-liquid separator II. The discharge port of the compressor is connected to the inlet A of the electromagnetic three-way valve I. The outlet B of the electromagnetic three-way valve I is connected to the inlet of the heat supply pipe. The outlet of the heat supply pipe is connected to the inlet A of the gas-liquid separator I. The liquid outlet B of the gas-liquid separator I is connected to the inlet of the liquid storage tank. The outlet of the liquid storage tank is connected to the inlet A of the electromagnetic three-way valve II. The outlet B of the electromagnetic three-way valve II is connected to the inlet of the throttler. The outlet of the throttler is connected to the inlet of the heat collecting pipe. The outlet of the heat collecting pipe is connected to the inlet A of the gas-liquid separator II. The gas outlet C of the gas-liquid separator II is connected to the inlet A of the electromagnetic three-way valve III. The outlet B of the electromagnetic three-way valve III is connected to the inlet of the return pipe. The outlet of the return pipe is connected to the suction port of the compressor. The return pipe is coiled around the outer shell of the compressor. The above circuit forms the main circulation circuit of the heat carrier;

[0012] It also includes a mixing chamber. The gas outlet C of the gas-liquid separator I is connected to an inlet of the mixing chamber through a connecting pipe. The other inlet of the mixing chamber is connected to the liquid outlet B of the gas-liquid separator II through a connecting pipe. The outlet of the mixing chamber is connected to the pipeline between the gas-liquid separator II and the electromagnetic three-way valve III through a connecting pipe. A one-way valve is provided on each connecting pipe to form the first auxiliary branch of the heat carrier;

[0013] It also includes a compressor superheat rapid boost component including a return pipe and a bypass pipe. The bypass pipe is provided with a heating sleeve on the outside. The inlet of the bypass pipe is connected to the auxiliary port C of the electromagnetic three-way valve I. The outlet of the bypass pipe is connected to the auxiliary port C of the electromagnetic three-way valve III to form the second auxiliary branch of the heat carrier;

[0014] It also includes a compressor exhaust temperature equalization and regulation component, which includes an electromagnetic flow valve and a capillary tube. The electromagnetic flow valve is arranged on the capillary tube. The inlet of the electromagnetic flow valve is connected to the auxiliary port C of the electromagnetic three-way valve II. The outlet of the electromagnetic flow valve is connected to the inlet of the capillary tube. The outlet of the capillary tube is connected to the heat carrier filling port of the compressor, forming a third auxiliary branch of the heat carrier.

[0015] Furthermore, the suction pipe is selected as a copper pipe with an outer diameter of 10.0 mm, a wall thickness of 1.0 mm, and a length of 2.5 m. The suction pipe is spirally wound around the outer shell of the compressor; the bypass pipe is made of a copper pipe with an outer diameter of 16.0 mm and a wall thickness of 1.0 mm. The bypass pipe inside the heating jacket is spiral. The rated power of the heating jacket is 50 W, and the heating temperature is 40 °C; the capillary tube is made of a copper pipe with an outer diameter of 3.0 mm and a wall thickness of 0.5 mm. The length unit of the capillary tube is cm, and the value is 1 / 5 of the rated power of the compressor.

[0016] Furthermore, the control component includes a PLC controller and a control panel. The temperature sensor, pressure sensor, displacement sensor, throttle, electromagnetic three-way valve I, electromagnetic three-way valve II, electromagnetic three-way valve III, heating jacket, and electromagnetic flow valve are all connected to the PLC controller. The PLC controller, compressor, gas-liquid separator I, and gas-liquid separator II are all connected to the control panel.

[0017] Furthermore, the heat collecting pipe includes a pipe body and a protective cover at its end. The pipe body consists of an outer sleeve pipe and a base pipe from outside to inside. The inner cavity of the base pipe is filled with heat storage material. A heat carrier circulation pipe is spirally wound around the outer surface of the base pipe. Thermal conductive mortar is filled between the base pipe and the outer sleeve pipe. The heat carrier circulation pipe is immersed in the thermal conductive mortar; the heat supply pipe and the heat collecting pipe have the same structure.

[0018] Furthermore, the outer sleeve pipe is a 201 stainless steel pipe with an outer diameter of 114 mm and a wall thickness of 2 mm; the thermal conductive mortar is a metal-based thermal conductive mortar with a thermal conductivity of 2.0 - 2.5 W / (m·K); the thermal conductivity of the heat supply pipe and the heat collecting pipe is higher than that of the subgrade filler. The thermal conductivity of the subgrade filler is 0.5 - 2.0 W / (m·K);

[0019] The heat carrier circulation pipe is selected as a copper pipe with an outer diameter of 6.0 mm and a wall thickness of 0.6 mm; the base pipe is selected as a steel wire mesh skeleton composite PVC pipe with an outer diameter of 75 mm; the heat storage material is silty soil or sandy soil with a moisture content of 20% - 30%;

[0020] The heat carrier is a medium-high temperature heat carrier R134a, whose boiling point is -26.1 °C and critical temperature is 101.1 °C; the filling amount of the heat carrier is in grams and the value is 3.5 times the rated power of the compressor;

[0021] The compressor adopts a fully enclosed single-stage piston compressor with a rated input power of 100 - 600W; the gas-liquid separator I is a gravity sedimentation type separator, and the gas-liquid separator II is a baffle separation type separator; the liquid storage tank adopts an inverted conical tank body, and the throttler adopts an electronic expansion valve.

[0022] Furthermore, the cabinet includes a cabinet body and a base at its bottom. A switchable cabinet door is provided on the front side of the cabinet body, and the interior is divided into three layers by two parallel pallets in the middle. The two pallets are the upper pallet and the lower pallet respectively. The two sides of the upper pallet and the lower pallet are respectively slidably matched with the guide rails on the inner wall of the cabinet body; vertically arranged upper and lower shielding plates are provided on the inner side of the cabinet door. The upper and lower shielding plates are arranged outside the guide rails, and the upper pallet is arranged between the upper and lower shielding plates; the control assembly is arranged on the upper shielding plate, and left and right windows are respectively provided on the left and right side walls of the cabinet body;

[0023] The compressor, electromagnetic three-way valve I, electromagnetic three-way valve II, electromagnetic three-way valve III, liquid storage tank and mixing chamber are arranged on the upper pallet, and the bypass pipe, electromagnetic flow valve, capillary tube, gas-liquid separator I, throttler and gas-liquid separator II are arranged on the lower pallet; the control assembly is arranged on the upper shielding plate.

[0024] The present invention also provides a method for preventing and controlling the frost heaving disease of railway subgrade suitable for severe cold climate, including the following steps:

[0025] 1) Assemble and install the above prevention and control system, and design the layout parameters of the heat supply pipe and the heat collection pipe and the heat supply capacity of the heat production unit;

[0026] Start the ground source heat pump device, and input the design parameters on the control panel of the control assembly; start the compressor, and at the same time open the main circulation loop, and close the second auxiliary branch of the compressor superheat rapid increase component and the third auxiliary branch of the compressor exhaust temperature equalization adjustment component;

[0027] 2) Regularly collect the measured values of the temperature sensors on the subgrade and the displacement sensors on the track at a fixed interval time t of 10 - 30 minutes;

[0028] 3) Calculate the differential frost heaving deformation amount of the track structure, that is, the amplitude of the track unevenness, through the PLC controller of the control assembly, and obtain the average temperature of the subgrade freezing depth and the harmful freezing depth range according to the linear interpolation of the subgrade temperature sensor;

[0029] 4) When the differential frost heaving deformation amount is less than the specified track unevenness management limit value, it indicates that it is in the prevention stage of frost heaving disease; the operation mode control scheme of the ground source heat pump device is as follows:

[0030] According to the weather forecast and the measured data in step 2), with a fixed interval time t of 10 - 30 min, the PLC controller calculates the required heating capacity and obtains the required heat carrier flow rate and the corresponding throttle opening degree.

[0031] The calculation method of the heat carrier flow rate is the heating power of a single heat pump divided by the phase change latent heat value of the heat carrier, and the calculation method of the throttle opening degree is the ratio of the heat carrier flow rate to the maximum allowable flow rate.

[0032] 5) When the differential frost heave deformation amount is greater than the specified management limit value of track unevenness, it indicates that it has entered the rapid post-disaster rectification stage of frost heave damage; the operation mode control scheme of the ground source heat pump device is as follows:

[0033] Open the throttle opening degree to 70% until the differential frost heave deformation amount of the track is reduced within the management limit value, and then resume to the operation mode of step 4).

[0034] Furthermore, in step 4), the operation mode of the ground source heat pump device is adjusted by the operating state of the compressor, and the adjustment logic is as follows:

[0035] 1) Perceive and display the temperature sensors and pressure sensors arranged in the heating unit at a fixed interval of 10 min.

[0036] 2) The PLC controller calculates the evaluation indexes of the compressor, including the compression ratio, suction superheat degree, and discharge superheat degree.

[0037] 3) According to the compressor evaluation indexes, execute the control commands for the compressor superheat rapid increase component and the compressor discharge temperature equalization adjustment component. The specific scheme is as follows:

[0038] ① When the displayed suction superheat degree is lower than 5°C, the PLC controller controls to open the compressor superheat rapid increase component. /

[0039] ② When the displayed compression ratio is greater than 8, the PLC controller controls the compressor discharge temperature equalization adjustment component to perform jet enthalpy increase at a rate of 1 / 200 of the total heat carrier charge per minute.

[0040] ③ When the displayed discharge superheat degree is greater than 20°C, the PLC controller controls the compressor discharge temperature equalization adjustment component to perform liquid injection cooling at a rate of 1 / 100 of the total heat carrier charge per minute.

[0041] The operations in the above steps ①, ②, and ③ are adjusted according to the corresponding compressor evaluation indexes at a fixed interval of 10 min to control the opening and closing of the compressor superheat rapid increase component and the compressor discharge temperature equalization adjustment component.

[0042] Furthermore, in step 1), the longitudinal spacing between the heating pipes of adjacent roadbeds is 2R, and the thermal influence radius of the heating pipe is calculated as follows:

[0043] (1)

[0044] In the formula, T0 is the outer wall temperature of the heating pipe, which is equal to the set value of the exhaust temperature of the compressor, in °C; T f is the target temperature of the roadbed filler, generally taken as the freezing temperature of the filler, in °C; T s is the lowest daily average temperature during the freezing period at the harmful freezing depth of the ordinary roadbed, in °C; K s is the correction coefficient of the roadbed filler, taken as the compaction coefficient of the roadbed, that is, when the roadbed compaction is poor, the thermal influence radius decreases accordingly; a is the thermal diffusivity of the filler, in m 2 / h; τ is the time, in h; H1 is the harmful freezing depth of the roadbed, in m;

[0045] The gauge of the railway is taken as the standard gauge of 1.435 m. The heating pipes on both sides are laid directly below the rails on both sides of the center of the railway line. The length of the heating pipe is calculated as follows:

[0046] (2)

[0047] In the formula, k is the width-to-height ratio of the roadbed slope; b is the shoulder width, in m; B is the ballast width of a single-track railway or the ballast width of the up-line or down-line of a double-track railway, in m;

[0048] The heating capacity of the heating unit is calculated as follows:

[0049] (3)

[0050] In the formula, λ1 is the surface convective heat transfer coefficient, in W / (m 2 ·°C); h is the roadbed height, in m; T a is the daily average temperature; ΔH is the growth rate of the freezing depth of the ordinary roadbed, in m / s; ρ is the density of the roadbed filler, in kg / m 3 ; c is the specific heat capacity of the roadbed filler, in J / (kg·°C);

[0051] The height of the heat collecting pipe is calculated as follows:

[0052] (4)

[0053] In the formula, H2 is the buried depth at the top of the heat carrier circulation pipeline, taken as the maximum natural surface freezing depth, in m; d is the equivalent heat absorption diameter of the stainless steel outer casing for the ground temperature energy, in m; λ2 is the heat transfer coefficient at the contact interface between the stainless steel outer casing and the foundation soil, in W / (m 2 ·°C); T eis the average temperature of the heat carrier circulation pipeline of the ground-based heat collecting pipe, °C; T g is the average ground temperature in the range below the maximum frost depth of the foundation.

[0054] Compared with the prior art, the technical progress achieved by the present invention lies in:

[0055] In the present invention, a number of heating units are arranged at intervals along the length direction of the railway at the toe of the subgrade slope. A heat supply pipe is horizontally laid in the frost heaving development layer of the subgrade, and heat collecting pipes are arranged in the stable layers at the lower parts on both sides of the subgrade. The heat supply pipe is connected to the heat collecting pipe through the heating unit; temperature sensors, pressure sensors and displacement sensors are used to monitor the harmful freezing temperature of the subgrade and the temperature of the heat carrier in the pipeline, monitor the suction and exhaust pressures of the compressor, and detect the deformation of the track respectively; the mixing chamber of the heating component, the superheat rapid increase component of the compressor and the exhaust temperature equalization adjustment component of the compressor respectively form three auxiliary branches, which can guarantee and improve the heating performance of the main circulation loop. By adopting the present invention, it is possible to ensure the rapid establishment of the superheat of the compressor at the start-up stage of the ground-source heat pump device in the severe cold environment, reasonably control the exhaust temperature range and operation mode of the compressor during the normal operation stage, realize the rapid start-up and long-term stable operation of the compressor in the severe cold climate environment, reduce the operation energy consumption, and improve the service life. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] The drawings are used to provide a further understanding of the present invention, and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention, and do not constitute a limitation to the present invention.

[0057] In the drawings:

[0058] Figure 1 is a schematic layout diagram of a railway subgrade frost heaving disease prevention and control system adapted to severe cold climate provided by an embodiment of the present invention inside and outside the railway subgrade;

[0059] Figure 2 is a schematic structural diagram of a ground-source heat pump device in an embodiment of the present invention;

[0060] Figure 3 is Figure 1 a schematic layout diagram of the ground-source heat pump device relative to the railway subgrade in;

[0061] Figure 4 is a schematic structural diagram of a cabinet in an embodiment of the present invention;

[0062] Figure 5 is an external view of a compressor in an embodiment of the present invention;

[0063] Figure 6 is a schematic structural diagram of an electromagnetic three-way valve I in an embodiment of the present invention;

[0064] Figure 7 Schematic structural diagram of the gas-liquid separator I in the embodiment of the present invention;

[0065] Figure 8 Schematic structural diagram of the gas-liquid separator II in the embodiment of the present invention;

[0066] Figure 9 Schematic installation diagram of the bypass pipe in the embodiment of the present invention;

[0067] Figure 10 External view of the pipe body in the embodiment of the present invention;

[0068] Figure 11 is Figure 10 Schematic internal structure diagram of the pipe body in

[0069] Figure 12 is Figure 10 Schematic cross-sectional structure diagram of the pipe body in

[0070] Figure 13 Schematic working principle diagram of the ground source heat pump device in the embodiment of the present invention;

[0071] Figure 14 Schematic structural layout diagram on the upper support plate of the cabinet in the embodiment of the present invention;

[0072] Figure 15 Schematic structural layout diagram on the lower support plate of the cabinet in the embodiment of the present invention;

[0073] Figure 16 Schematic layout diagram of the heating unit in the cabinet in the embodiment of the present invention;

[0074] In the figure:

[0075] 1 - Heating unit, 2 - Heat supply pipe, 3 - Collector pipe, 4 - Roadbed, 5 - Foundation, 6 - Cabinet, 601 - Base, 602 - Cabinet body, 603 - Upper support plate, 604 - Lower support plate, 605 - Upper cover plate, 606 - Lower cover plate, 607 - Left window, 608 - Right window, 7 - Compressor, 701 - Compressor suction port, 702 - Compressor discharge port, 703 - Compressor heat carrier filling port, 8 - Electromagnetic three - way valve I, 801 - Inlet A of electromagnetic three - way valve I, 802 - Outlet B of electromagnetic three - way valve I, 803 - Auxiliary port C of electromagnetic three - way valve I, 9 - Gas - liquid separator I, 901 - Inlet A of gas - liquid separator I, 902 - Liquid outlet B of gas - liquid separator I, 903 - Gas outlet C of gas - liquid separator I, 10 - Liquid storage tank, 11 - Electromagnetic three - way valve II, 1102 - Outlet B of electromagnetic three - way valve II, 1103 - Auxiliary port C of electromagnetic three - way valve II, 12 - Throttle, 13 - Gas - liquid separator II, 1301 - Inlet A of gas - liquid separator II, 1302 - Liquid outlet B of gas - liquid separator II, 1303 - Gas outlet C of gas - liquid separator II, 14 - Electromagnetic three - way valve III, 1401 - Inlet A of electromagnetic three - way valve III, 1403 - Auxiliary port C of electromagnetic three - way valve III, 15 - Return air pipe, 16 - Connecting pipe, 17 - Mixing chamber, 18 - Check valve, 19 - Bypass pipe, 20 - Electric heating sleeve, 21 - Electromagnetic flow valve, 22 - Capillary tube; 26 - Track, 27 - PLC controller, 28 - Control panel, 29 - Pipe body, 30 - Protective cover, 31 - Outer sleeve pipe, 32 - Heat - conducting mortar, 33 - Heat - carrier circulation pipe, 34 - Base pipe, 35 - Heat - storage material. Detailed implementation manners

[0076] The following specific embodiments can be combined with each other, and the same or similar concepts or processes may not be repeated in some embodiments. The embodiments of the present invention will be described below with reference to the accompanying drawings.

[0077] Such as Figure 1 、 Figure 2 And Figure 3As shown in the figure, a prevention and control system for frost heaving diseases of railway subgrades adapted to severe cold climates. The prevention and control system includes several groups of ground source heat pump devices arranged at intervals along the length direction of the railway subgrade 4. The ground source heat pump device includes a heating unit 1, a heat supply pipe 2, a heat collection pipe 3 and a detection component. The heat collection pipe 3 is connected to the heat supply pipe 2 through the heating unit 1. The heating unit 1 is located on the surface of the foundation 5 at the toe of the subgrade 4. The heat supply pipe 2 is horizontally laid in the frost heaving development layer of the subgrade 4 and perpendicular to the length direction of the subgrade 4. The heat collection pipe 3 is vertically located in the lower stable layer of the foundation 5 on both sides of the subgrade 4. The detection component includes a temperature sensor, a pressure sensor and a displacement sensor. Temperature sensors are provided in the subgrade 4, in the middle of the heat collection pipe 3 and on the pipeline of the heating unit 1, respectively, for monitoring the harmful freezing temperature of the subgrade and the temperature of the heat carrier in the pipeline. Pressure sensors are provided at the suction port and the discharge port of the compressor of the heating unit 1 for monitoring the suction and discharge pressures of the compressor. The displacement sensor is arranged at the web of the railway track 26 for detecting the deformation amount of the track 26. The heating unit 1, the temperature sensor, the pressure sensor and the displacement sensor are all connected to the control component.

[0078] In specific design, 5 temperature sensors are designed: The 1st temperature sensor is arranged at the middle position of the heat collection pipe 3 to monitor the evaporation temperature. The 2nd temperature sensor is arranged on the return pipe 15 adjacent to the suction port 701 of the compressor to monitor the return air temperature of the heat carrier entering the compressor. The 3rd temperature sensor is arranged on the pipeline adjacent to the discharge port 702 of the compressor to monitor the discharge air temperature of the heat carrier discharged after the work of the compressor. The 4th temperature sensor is arranged on the top surface of the subgrade 4. The 5th temperature sensor is arranged at the position of the harmful freezing depth of the subgrade.

[0079] 2 pressure sensors are designed: The 1st pressure sensor is arranged on the return pipe 15 of the suction port 701 of the compressor to monitor the suction pressure of the compressor. The 2nd pressure sensor is arranged on the pipeline of the discharge port 702 of the compressor to monitor the discharge pressure of the compressor.

[0080] 2 displacement sensors are designed: The 1st displacement sensor is arranged at the web position of the upper track 26 of the mileage where the heat supply pipe of the subgrade is located. The 2nd displacement sensor is arranged at the web position of the upper track structure in the middle mileage between adjacent heat supply pipes on the same side of the track to monitor the absolute frost heaving amount and the differential frost heaving amount of the track respectively.

[0081] In a specific embodiment of the present invention, as Figures 6 - 8As shown in FIGS. 13 and 16, the heating unit 1 includes a cabinet 6 and a heating component. The heating component and the control component are both arranged in the cabinet 6. The heating component is connected to the heating pipe 2 and the heat collecting pipe 3 through pipelines. The heating component can realize the condensation and liquefaction and evaporation and gasification of the heat carrier, and is respectively used for heating the roadbed 4 and absorbing heat from the ground base 5. The heating component includes a compressor 7, a gas-liquid separator I 9, a liquid storage tank 10, a throttler 12, a gas-liquid separator II 13, a mixing chamber 17, a compressor superheat rapid increase component and a compressor exhaust temperature equalization adjustment component. The exhaust port 702 of the compressor is connected to the inlet A801 of the electromagnetic three-way valve I 8. The outlet B802 of the electromagnetic three-way valve I is connected to the inlet of the heating pipe 2. The outlet of the heating pipe 2 is connected to the inlet A901 of the gas-liquid separator I 9. The liquid outlet B902 of the gas-liquid separator I 9 is connected to the inlet of the liquid storage tank 10. The outlet of the liquid storage tank 10 is connected to the inlet A of the electromagnetic three-way valve II 11. The outlet B1102 of the electromagnetic three-way valve II 11 is connected to the inlet of the throttler 12. The outlet of the throttler 12 is connected to the inlet of the heat collecting pipe 3. The outlet of the heat collecting pipe 3 is connected to the inlet A of the gas-liquid separator II 13. The gas outlet C1303 of the gas-liquid separator II 13 is connected to the inlet A1401 of the electromagnetic three-way valve III 14. The outlet B of the electromagnetic three-way valve III 14 is connected to the inlet of the return pipe 15. The outlet of the return pipe 15 is connected to the suction port 701 of the compressor 7. The return pipe 15 is coiled around the outer shell of the compressor 7, and the above circuit forms the main circulation circuit of the heat carrier.

[0082] As shown in Figure 7 , 13 FIGS., the gas outlet C903 of the gas-liquid separator I 9 is connected to the liquid outlet B1302 of the gas-liquid separator II 13 through the mixing chamber 17. The gas outlet C903 of the gas-liquid separator I 9 is connected to an inlet of the mixing chamber 17 through a connecting pipe 16. The other inlet of the mixing chamber 17 is connected to the liquid outlet B of the gas-liquid separator II 13 through a connecting pipe 16. The outlet of the mixing chamber 17 is connected to the pipeline between the gas-liquid separator II 13 and the electromagnetic three-way valve III 14 through a connecting pipe 16. One-way valves 18 are provided on all 3 connecting pipes 16 to prevent the backflow of the heat carrier caused by the pressure difference, thereby forming the first auxiliary branch of the heat carrier. The beneficial effects of the first auxiliary branch are as follows:

[0083] On the one hand, during the operation of the prevention and control system, the residual gaseous heat carrier after the heat carrier in the roadbed heating pipe releases heat and condenses is separated by gas-liquid separator I9 and can be directly mixed with the residual liquid heat carrier after evaporation and absorption in the foundation 5 heat collecting pipe, separated by gas-liquid separator II13. Leveraging the high temperature and high pressure of the gaseous heat carrier separated by gas-liquid separator I9, the low-temperature and low-pressure liquid heat carrier separated by gas-liquid separator II13 is directly vaporized and enters the main circulation of compressor 7, avoiding damage caused by "liquid hammer" in the compressor. On the other hand, during compressor shutdown, the pressure balance between the high-pressure and low-pressure sides of the heating component can be accelerated, reducing the pressure differential resistance when the compressor is restarted, which is conducive to quickly entering normal operation.

[0084] The compressor superheat rapid increase component includes a return air pipe 15 and a bypass pipe 19. The compressor superheat rapid increase component is divided into a passive part and an active part. The passive part refers to the return air pipe 15 in the main circulation loop of the heating component; the active part refers to: the bypass pipe 19 and the heating jacket 20 outside it. Figure 6 、 9 As shown, bypass pipe 19 is connected as follows: its inlet is connected to auxiliary port C803 of electromagnetic three-way valve I8, and its outlet is connected to auxiliary port C1403 of electromagnetic three-way valve III14, forming a second auxiliary branch for the heat carrier. Its operating principle is to return the refrigerant discharged from the compressor through the bypass pipe to the return air pipe, where it re-enters the compressor, thereby increasing the return air temperature and, in turn, the compressor superheat. The beneficial effects of this second auxiliary branch are as follows:

[0085] At the initial stage of compressor startup, the bypass pipe is opened to suppress the heat carrier flow and heat dissipation on the high-pressure side of the main circuit of the heating cycle. Assisted by electric heating compensation, the problem of the heating component being unable to quickly establish compressor superheat and the startup taking too long due to the low ambient temperature is solved.

[0086] The bypass pipe 19 is constructed from a copper tube with an outer diameter of 16.0 mm and a wall thickness of 1.0 mm. The bypass pipe 19 is spirally shaped within the heating jacket 20. The heating jacket 20 is rated for 50W and a heating temperature of 40°C. The heating jacket and the solenoid valves at both ends of the bypass pipe open and close in tandem. Compared to other connecting pipes and the return air pipe, the bypass pipe has the largest diameter to reduce the extended resistance to the gaseous heat carrier's migration, allowing it to quickly form a closed bypass branch with the compressor, quickly establishing the required superheat and shortening compressor startup time. The bypass pipe is threadedly connected to the electromagnetic three-way valves I and III, allowing for flexible disassembly and installation for ease of installation and maintenance.

[0087] The compressor exhaust temperature balance adjustment component includes an electromagnetic flow valve 21 and a capillary tube 22. Figure 13As shown, the electromagnetic flow valve 21 is disposed on the capillary tube 22, and the electromagnetic flow valve 21 is disposed at the inlet end of the capillary tube 22. The inlet of the electromagnetic flow valve 21 is connected to the auxiliary port C1103 of the electromagnetic three-way valve II 11. The outlet of the electromagnetic flow valve 21 is connected to the inlet of the capillary tube 22. The outlet of the capillary tube 22 is connected to the heat carrier filling port 703 of the compressor 7, forming a third auxiliary branch of the heat carrier. Its working principle is: The liquid heat carrier in the liquid storage tank is directly shunted to the compression chamber of the compressor through the electromagnetic flow valve, increasing the heat carrier inside the compressor, which helps to solve the problem of too high exhaust temperature of the compressor caused by the low gasification rate of the heat carrier inside the ground heat collecting tube and the small return air volume or even air extraction in the compressor in extremely cold environments. The beneficial effects of the third auxiliary branch are as follows:

[0088] The combined scheme of the electromagnetic flow valve and the capillary tube is adopted, which has both flow regulation and phase state regulation capabilities, and can flexibly complete two types of compressor state regulation methods, namely jet enthalpy increase and liquid injection cooling, according to the compressor state. The principle is that, on the one hand, according to the compressor exhaust temperature level, the electromagnetic flow valve can be used to control the heat carrier shunt flow; on the other hand, the capillary tube can be used to control the phase state of the heat carrier when it enters the compression. Specifically, by adjusting the diameter and length of the capillary tube, when the heat carrier shunt flow is small, the heat carrier will be completely gasified after passing through the capillary tube, which is "jet enthalpy increase", helping to directly increase the mass flow rate of the heat carrier in the main cycle, thereby increasing the heating capacity and indirectly reducing the exhaust temperature and compression ratio of the compressor, improving the operating state of the compressor; when the shunted heat carrier increases, the heat carrier will become a gas-liquid mixture after passing through the capillary tube, playing a role in increasing the return air volume to the compressor and absorbing heat by liquid gasification to cool down; when the shunted heat carrier continues to increase, the proportion of the liquid heat carrier further increases, which is "liquid injection cooling", playing a role in quickly cooling the compressor, and the control intensity of the compressor exhaust temperature and compression ratio gradually increases.

[0089] During specific production, the flow rate adjustment range of the electromagnetic flow valve 21 per minute is 1 / 200 to 1 / 20 of the heat carrier filling amount; the capillary tube is made of a copper tube with an outer diameter of 3.0 mm and a wall thickness of 0.5 mm, and the unit of the length of the capillary tube is cm, and the value is 1 / 5 of the rated power of the compressor. For example, if the rated input power of the compressor is 200 W, then the length of the capillary tube is 40 cm.

[0090] As Figure 5As shown in the figure, the suction pipe 15 is a copper pipe with an outer diameter of 10.0 mm, a wall thickness of 1.0 mm, and a length of 2.5 m. The suction pipe is spirally wound around the outer shell of the compressor. Its working principle is that before the gaseous heat carrier in the ground heat collecting pipe enters the compressor inlet, it further absorbs the heat of the compressor outer shell, thereby increasing the gaseous temperature. The beneficial effect of the suction pipe 15 is that by using the main circulation loop of the heating component, without adding additional control links, it can continuously achieve the effects of increasing the superheat degree at the compressor suction port and reducing the temperature of power units such as the internal motor of the compressor, thus preventing the compressor exhaust temperature from being too high and the compression ratio from being too large. In fact, it is the passive part of the compressor superheat rapid increase component of the present invention.

[0091] In specific design, the compressor 7 adopts a fully enclosed single-stage piston compressor with a rated input power of 100 - 600 W. Its characteristics are simple structure, small lubricating oil consumption, long tolerance time for overload, light load, and no load, and it is more adaptable to extremely cold environments and the vibration environment on the side of the railway line.

[0092] The gas-liquid separator I 9 is a gravity settling type separator, with the main function of degassing. The purpose is to separate the gaseous heat carrier when the heat carrier enters the liquid storage tank, avoiding the influence of the liquid heat carrier carrying gas on the pressure reduction effect of the throttle in the main circulation loop of the heating component and the low-pressure side pressure, and ensuring the gasification heat absorption efficiency of the heat carrier on the low-pressure side.

[0093] The gas-liquid separator II 13 is a baffle separation type separator, with the main function of liquid removal. The purpose is to separate the liquid heat carrier in the return gas, avoiding liquid slugging damage to the compressor caused by the return gas carrying liquid.

[0094] The liquid storage tank 10 adopts an inverted conical tank body, which on the one hand plays a role in redundant adjustment of the heat carrier, and on the other hand is beneficial to maintaining the pressure required for the heat carrier to flow out of the liquid storage tank. The volume of the liquid storage tank is taken as 1.5 times the volume of the liquid heat carrier filling.

[0095] The throttle 12 adopts an electronic expansion valve, which can continuously and finely adjust the opening of the expansion valve and the heat carrier flow rate, improving the operating performance of the heat system under variable working conditions. The selection basis of the electronic expansion valve is that when the opening is 70%, it corresponds to the maximum heat carrier flow rate of the compressor. The beneficial effect of the combined use of the liquid storage tank and the electronic expansion valve is that the injected heat carrier does not have to all participate in the heating cycle, but can flexibly adjust the heat carrier circulation amount according to the target heating capacity and heating temperature through the electronic expansion valve.

[0096] Each component of the main circulation loop of the heating component is connected by a copper pipe with an outer diameter of 8.0 mm and a wall thickness of 1.0 mm. The connection method is welding and it is not flexibly detachable, aiming to increase the stability of the equipment in the vibration environment beside the roadbed. The copper pipe is installed in a high-density rubber and plastic insulation pipe with an outer diameter of 30 mm and an inner diameter of 8 mm, aiming to reduce the heat loss along the way during the heating cycle in extremely cold climate environments.

[0097] The heat carrier is selected as the medium-high temperature heat carrier R134a, whose boiling point is -26.1 °C and critical temperature is 101.1 °C. The advantage for the scenario of preventing and controlling roadbed frost heaving diseases is that through the pressure adjustment on the low-pressure side and high-pressure side in the main circulation loop of the heating component, the heat exchange temperature can be autonomously adjusted. The heat absorption temperature of the geothermal collector pipe (the evaporation temperature at the middle position) is generally set at -10 to -20 °C, and in extreme cases, it can be reduced to about -25 °C, ensuring the collection efficiency of the heating component for low-grade geothermal energy in extremely cold environments; the target heating temperature T0 (the exhaust gas temperature of the compressor) of the roadbed heating pipe is generally set at 60 to 80 °C, and in extreme cases, it can be increased to about 100 °C, ensuring the timeliness of heating and preventing frost heaving of the roadbed. The two are in a negative correlation. When the throttle opening is smaller, that is, the heat carrier circulation volume is lower, the heat absorption temperature of the geothermal collector pipe is lower, and the exhaust gas temperature of the compressor is higher, but the heating capacity is smaller; when the throttle opening gradually increases, that is, the heat carrier circulation volume increases, the heat absorption temperature of the geothermal collector pipe gradually increases, the exhaust gas temperature of the compressor gradually decreases, but the heating capacity gradually increases.

[0098] For the determination method of the filling amount of the heat carrier R134a, the present invention adopts an empirical value-taking method that comprehensively considers the internal volume of the main circulation loop of the heating component and the maximum exhaust gas volume of the compressor during the equipment trial production and application process, and takes it as 3.5 times the rated input power of the compressor. For example, if the rated input power of the compressor is 200 W, then the filling amount of the heat carrier is 700 g.

[0099] During the operation of the above heating component, the compressor exhaust port 702, the heating pipe 2, the gas-liquid separator I9, and the liquid storage tank 10 are the high-pressure side, and the working pressure range is 1.2 - 1.8 MPa; the compressor suction port 702, the gas-liquid separator II13, the collector pipe 3, and the throttle 12 are the low-pressure side, and the working pressure range is 150 - 250 kPa. Its working principle is: the heat carrier repeats the closed cycle of compression - condensation and liquefaction - throttling and pressure reduction - evaporation and gasification - compression driven by the compressor, uses the work done by the compressor to achieve efficient heat conversion, and uses the latent heat of phase change of the heat carrier to achieve efficient heat collection and transfer. Condensation and liquefaction and evaporation and gasification respectively realize the functions of heating the roadbed and absorbing heat from the foundation, corresponding to the heating pipe located on the roadbed and the collector pipe located on the foundation respectively.

[0100] When the above-mentioned ground source heat pump device is applied in an extremely cold climate environment, it mainly ensures the safe operation of the compressor. The first evaluation index of the compressor operation state is the superheat degree of heat absorption, and its reasonable range is 5-8°C. The calculation method is the difference between the compressor suction temperature and the evaporator inlet temperature. The first problem faced by the roadbed ground source heat pump system in an extremely cold environment is that the suction superheat degree is too low during the start-up stage, which will cause the compressor suction temperature to be too low, the suction volume to be small or even air extraction, resulting in the compressor being unable to enter the normal operation state.

[0101] The second evaluation index of the compressor operation state is the superheat degree of exhaust temperature, and its reasonable range is 0-20°C. The calculation method is the difference between the compressor exhaust temperature and the exhaust temperature target value. The second problem faced by the roadbed ground source heat pump system in a severe cold environment is that the exhaust superheat degree is too high during the operation stage, resulting in high-temperature alarms of the compressor, carbonization of lubricating oil, damage to the oil film and damage to the whole machine, and the normal state can only be maintained for a short time. The main reason for the too high exhaust temperature is caused by the too low suction volume of the compressor in an extremely cold environment and the low heat dissipation rate of the motor during light load or no load, resulting in deterioration of the internal lubricating oil of the compressor, damage to the oil film and damage to the motor.

[0102] The third evaluation index of the compressor operation state is the compression ratio, which refers to the ratio of the compressor discharge port pressure to the suction port pressure. The reasonable range of the compression ratio is 3-8. When the heat carrier return air volume is too low, the compression ratio is small, which is called light load or no load, which is the main problem caused by the extremely cold environment of the roadbed ground source heat pump system. When the heat carrier return air volume is large, the compression ratio is large, which is called overload, caused by too large a throttle opening and poor heat dissipation of the roadbed heating pipe. The third problem faced by the roadbed ground source heat pump device in a severe cold environment is that the heat carrier flow rate is not adjusted according to the actual heating demand of the roadbed, resulting in excessive energy consumption of the compressor.

[0103] In a specific embodiment of the present invention, as Figure 4 shown, the control component includes a PLC controller 27 and a control panel 28. The temperature sensor, pressure sensor, displacement sensor, throttle 12, electromagnetic three-way valve I 8, electromagnetic three-way valve II 11, electromagnetic three-way valve III 14, heating sleeve 20, and electromagnetic flow valve 21 are all connected to the PLC controller 27. The PLC controller 27, compressor 7, gas-liquid separator I 9, and gas-liquid separator II 13 are all connected to the control panel 28. The PLC controller 27 is used to store and execute logical operations and operation instructions, and is connected to the aforementioned throttle, electromagnetic three-way valve, electromagnetic flow valve, electric heating sleeve, temperature sensor, pressure sensor, and displacement sensor. The connection method is that the aforementioned components are integrated into a wiring terminal, and the wiring terminal is then connected to the PLC controller. The control panel 28 includes a ground source heat pump operation mode setting area and a compressor operation state adjustment area. The PLC controller is connected to the control panel. Preferably, the control panel uses an HMI configuration screen.

[0104] In a specific embodiment of the present invention, as Figures 10 - 12 shown, the heat collecting pipe 3 includes a pipe body 29 and a protective cover 30 at its end. The pipe body 29 includes an outer sleeve pipe 31 and a base pipe 34 from outside to inside. The inner cavity of the base pipe 34 is filled with a heat storage material 35. A heat carrier circulation pipe 33 is spirally wound around the outer surface of the base pipe 34. A heat conduction mortar 32 is filled between the base pipe 34 and the outer sleeve pipe 31. The heat carrier circulation pipe 33 is immersed in the heat conduction mortar 32. The heat supply pipe 2 and the heat collecting pipe 3 have the same structure.

[0105] During specific production, the outer sleeve pipe 31 is made of 201 stainless steel pipe with an outer diameter of 114 mm and a wall thickness of 2 mm. Embedding it in the stress working area of the subgrade bed can also ensure the subgrade bearing performance requirements. At the same time, the embedded structure is corrosion-resistant, ensuring long-term durability.

[0106] The heat conduction mortar 32 is a metal-based heat conduction mortar with a thermal conductivity of 2.0 - 2.5 W / (m·K). The beneficial effects are as follows: In terms of the heat transfer path, the heat conduction coefficients of the subgrade heat supply pipe and the ground heat collecting pipe are slightly higher than that of the subgrade filler (generally 0.5 - 2.0 W / (m·K)). On the one hand, it is beneficial to maintain a coordinated heat transfer performance with the soil body, maintain a continuous temperature gradient during the heat transfer process, and prevent the heat dissipation condensation rate of the heat carrier circulation pipeline from being low and the poor heat supply effect of the subgrade. On the other hand, it prevents the excessive difference in the heat conduction performance between the pipe body and the soil body, resulting in the phenomenon of cold and heat accumulation and overflow loss at the contact interface position. [[ID=IO]]

[0107] The heat carrier circulation pipe 33 is selected as a copper pipe with an outer diameter of 6.0 mm and a wall thickness of 0.6 mm, and is spirally wound around the PVC base pipe. The method for determining the length is as follows: The length base number of the heat carrier circulation pipeline of the ground heat collecting pipe is 15 m, and then it is increased by 1 / 20 of the rated input power of the compressor. For example, for a compressor with a rated input power of 300 W, the length of the heat carrier circulation pipeline of the corresponding ground heat collecting pipe is 30 m. The purpose of this design is to shorten the heat dissipation along - path length of the subgrade heat supply pipe, which is beneficial to reducing the overall evaporation temperature level and improving the heat absorption efficiency of the ground geothermal energy. While the length base number of the heat carrier circulation pipeline of the subgrade heat supply pipe is 20 m, and then it is increased by 1 / 10 of the rated input power of the compressor. For example, for a compressor with a rated input power of 300 W, the length of the heat carrier circulation pipeline of the corresponding ground heat collecting pipe is 50 m. The purpose of this design is to increase the heat dissipation along - path length of the subgrade heat supply pipe, fully dissipate heat, and is beneficial to improving the overall circulation efficiency of the heat pump and the anti - freezing and swelling effect of the subgrade heat supply.

[0108] The base pipe 34 selects a wire-mesh framework composite PVC pipe with an outer diameter of 75 mm to play a role in fixing and supporting the copper pipe for the heat-carrying agent circulation pipeline; the heat storage material 35 adopts silt or sand with a moisture content of 20% - 30%. The purpose is that after the heating component stops operating, the ground collector pipe can continue to collect geothermal energy relying on the residual heat collection temperature gradient, improving the heat collection conditions when the heat pump restarts; the roadbed heating pipe can continue to supply heat to the roadbed relying on the residual heating temperature gradient, improving the ductility of the heating performance of the heating component, which is conducive to providing conditions for the compressor shutdown protection.

[0109] During specific production, as Figure 4 shown, the cabinet 6 includes a cabinet body 602 and a base 601 at its bottom. A switchable cabinet door is provided on the front side of the cabinet body 602, and the interior is divided into three layers by two parallel support plates in the middle. The two support plates are the upper support plate 603 and the lower support plate 604 respectively. The two sides of the upper support plate 603 and the lower support plate 604 are respectively slidably matched with the guide rails on the inner wall of the cabinet body 602, facilitating installation and disassembly; vertically arranged upper shielding plate 605 and lower shielding plate 606 are provided on the inner side of the cabinet door. The upper shielding plate 605 and the lower shielding plate 606 are arranged outside the guide rails, and the upper support plate 603 is arranged between the upper shielding plate 605 and the lower shielding plate 606; the control component is arranged on the upper shielding plate 605. Left window 607 and right window 608 are respectively provided on the left and right side walls of the cabinet body 602, and the left window 607 and the right window 608 are correspondingly arranged on both sides of the lower shielding plate 606. The upper shielding plate 605 and the lower shielding plate 606 are used to shield the components on the upper support plate 603 and the lower support plate 604 to prevent external dust from entering and affecting the operation of the equipment. During specific production, a stainless steel weather-resistant cabinet is selected for the cabinet, with dimensions of length × width × height = 50 cm × 50 cm × 50 cm. The upper support plate, the lower support plate, the upper shielding plate, the lower shielding plate and the cabinet are of an assembled structure, enabling flexible disassembly and assembly.

[0110] As Figure 14 、 15 、16 shown, the compressor 7, electromagnetic three-way valve I 8, electromagnetic three-way valve II 11, electromagnetic three-way valve III 14, liquid storage tank 10 and mixing chamber 17 are arranged on the upper support plate 603, and the bypass pipe 19, electromagnetic flow valve 21, capillary tube 22, gas-liquid separator I 9, throttle 12 and gas-liquid separator II 13 are arranged on the lower support plate 604; the control component is arranged on the upper shielding plate 605.

[0111] The specific assembly process of the above-mentioned ground-source heat pump device is as follows:

[0112] Step 1, respectively install and fix the components on the upper support plate, the lower support plate and the upper shielding plate.

[0113] Step 2: Push the upper support plate into the upper guide rail inside the cabinet and push the lower support plate into the lower guide rail inside the cabinet respectively.

[0114] Step 3: Connect the inlets and outlets of the compressor superheat rapid increase component on the lower support plate to the auxiliary port C of the electromagnetic three-way valve I and III, and connect the inlets and outlets of the compressor exhaust temperature equalization and regulation component to the auxiliary port C of the electromagnetic three-way valve II and the heat carrier filling port of the compressor respectively.

[0115] Step 4: Extend the two ports where the upper support plate is connected to the ground heat collecting pipe, that is, the outlet of the throttle 12 and the inlet A1301 of the gas-liquid separator II, to the left window of the lower shield and protrude; extend the two ports where the upper support plate is connected to the roadbed heating pipe, that is, the outlet B802 of the electromagnetic three-way valve I and the inlet A901 of the gas-liquid separator I, to the right window of the lower shield and protrude, so as to be connected to the ground heat collecting pipe and the roadbed heating pipe respectively.

[0116] Step 5: Connect the terminal to the PLC controller and fix the upper shield at the end of the cabinet guide rail. Thus, the production of the heating unit is completed and it can be used after being transported to the site.

[0117] The heating components are installed in the cabinet in units. The heating unit adopts a split structure, with high integration and disassembly efficiency, and is easy to assemble, overhaul, replace and upgrade. The heating component is the core functional part of the ground source heat pump device. The compressor superheat rapid increase component and the compressor exhaust temperature equalization and regulation component are detachable and freely combinable accessory structures, which can be shipped out of the factory after being integrated with the heating component into an overall product, or can be added as enhanced structures to the heating units that have been installed and applied on site.

[0118] Compared with the prior art, on the basis of the traditional ground source heat pump heating cycle components, the present invention adds a compressor superheat rapid increase component and a compressor exhaust temperature equalization and regulation component, enabling the heating unit to adapt to the severe cold climate environment, avoiding respectively the phenomenon of too slow start-up speed caused by insufficient suction superheat of the compressor during the start-up stage, and the phenomenon of too low compressor return gas volume and too high exhaust temperature caused by poor ground geothermal energy conditions, ensuring the operation reliability and long-term life of the ground source heat pump system, and improving the weather resistance. The heating unit adopts a double-layer unitized structure scheme, and the whole set of equipment is modular and unitized designed, which is easy to assemble, disassemble, overhaul, replace and upgrade. It also has an electromechanical integrated control component with the functions of operation state monitoring and regulation control, with high automation degree. It provides calculation and design methods for key contents such as the layout parameters of the roadbed heating pipe, the heating capacity of the heating unit, and the layout parameters of the ground heat collecting pipe, realizes the quantitative matching of the roadbed frost heave disease scenario, and improves the reliability. Generally, it solves the technical problems such as poor weather resistance and low operation reliability faced by the roadbed ground source heat pump system in the extreme cold climate environment.

[0119] The present invention also provides a method for preventing and controlling the frost heaving disease of railway subgrades adapted to severe cold climates, including the following steps:

[0120] 1) Assemble and install the above prevention and control system, and design the layout parameters of the heat supply pipes and heat collection pipes and the heat supply capacity of the heating unit;

[0121] Install the above ground source heat pump device at the location of the frost heaving disease of the subgrade. The specific construction content is as follows:

[0122] The first item: On-site installation of the subgrade heat supply pipe.

[0123] The layout form is: Horizontally arranged at a certain spacing in the frost heaving layer of the subgrade, perpendicular to the line direction. The layout parameters include: the body length, the vertical burial depth (the distance between the center line of the subgrade heat supply pipe and the top surface of the subgrade), and the longitudinal spacing. The values of the layout parameters are calculated and designed according to the specific frost heaving disease scenario of the subgrade.

[0124] The installation plan is: The first step, before the on-site construction, prepare the stainless steel outer casing and the heat carrier circulation pipeline in advance, and complete the filling and sealing of the heat storage material in the PVC base pipe. The second step, enter the site for construction and implant the stainless steel outer casing. For operating subgrades, use the method of mechanical drilling with a down-the-hole drill or a spiral drill. If the hole collapses seriously during the drilling process, in order to ensure the safe operation of the trains on the line, use the follow-the-hole drilling method; for newly built subgrades, use the method of directly burying by mechanical or manual grooving at the corresponding burial depth. The third step, insert the pre-prepared heat carrier circulation pipeline into the stainless steel outer casing.

[0125] The second item: On-site installation of the ground heat collection pipe.

[0126] The layout form is: In contrast to the position of the subgrade heat supply pipe, vertically arranged in the ground outside the toe of the subgrade slope. The distance from the toe of the slope should be kept more than 3m to prevent interference with the subgrade during the drilling construction and the heat collection process. The layout parameters include the height of the ground heat collection pipe body and the burial depth of the top of the heat carrier circulation pipeline. The values of the layout parameters are calculated and designed according to the heat supply performance of the ground source heat pump and the distribution conditions of the ground temperature energy.

[0127] The installation plan is: Similar to the subgrade heat supply pipe, the difference is that for both operating subgrades and newly built subgrades, the stainless steel outer casing is implanted by mechanical drilling.

[0128] The third item: On-site installation of the heating unit.

[0129] The layout form is: arranged on the foundation at the toe of the subgrade slope at a certain interval. The design parameter of the heating unit is the rated heating capacity, which is calculated and designed according to the specific subgrade frost heaving disease scenario and the subgrade heating pipe layout scheme. On the basis of clarifying the rated heating capacity of the ground source heat pump system, the selection methods of various components such as compressors are well-known in the industry and will not be elaborated here.

[0130] The installation scheme is as follows: Step 1, prepare the heating unit in advance before entering the construction site. Step 2, level the foundation after entering the site and pour a concrete foundation with dimensions of length × width × height = 70 cm × 70 cm × 20 cm. Step 3, fix the base at the bottom of the cabinet using expansion bolts and ensure the base is level to guarantee the normal operating conditions of the internal moving parts of the compressor. Step 4, place the cabinet on the base.

[0131] The fourth item: commissioning of the ground source heat pump device.

[0132] Step 1, connect the main circulation loop of the heating component, connect the heating unit, the ground collector pipe, and the subgrade heating pipe according to the aforementioned combination method, and wrap all the exposed connecting pipes with high-density rubber and plastic insulation pipes, and the outside of the rubber and plastic insulation pipes is protected by anti-aging PVC pipes. Step 2, turn on the power supply, operate the throttle valve, the three-way solenoid valve, and the electromagnetic flow valve to all open, test that they operate normally, and then close the auxiliary port C of the three-way solenoid valve II. Step 3, evacuate the inside of the heating component through a vacuum pump at the heat carrier filling port of the compressor. Step 4, inject the rated mass of liquid heat carrier into the pipeline of the heating unit through the heat carrier filling port. Step 5, restore the threaded connection between the heat carrier filling port of the compressor and the capillary outlet. Step 6, conduct a trial operation of the heating unit, set relevant parameters and observe the operating status through the control panel until it is normal. Step 7, inject heat-conducting mortar into the subgrade heating pipe and the ground collector pipe.

[0133] The design of the above ground source heat pump device includes the following contents:

[0134] The first item, calculation and design of the heating pipe layout parameters;

[0135] The calculation and design method for the vertical burial depth of the heat supply pipe in the subgrade is as follows: Through on-site exploration and monitoring of the frost heaving disease sites in the subgrade, the harmful freezing depth of the subgrade is obtained, which is the vertical burial depth of the heat supply pipe in the subgrade. The beneficial effect of this value-taking scheme is to form a heat barrier layer at the position of the harmful freezing depth. First, it prevents the continuous increase of the freezing depth of the subgrade in severe cold weather and realizes the prevention of frost heaving diseases. Second, it allows the subgrade above the harmful freezing depth to freeze, reducing the ineffective output of heat. Third, it increases the soil temperature and heat storage capacity in the range below the harmful freezing depth, enhancing the potential of the subgrade to resist extreme strong cooling weather such as cold snaps. At the same time, it is also necessary to ensure that the minimum value of the vertical burial depth of the heat supply pipe in the subgrade is 40 cm, aiming to avoid the concentrated distribution area of the additional stress of the train load on the subgrade.

[0136] The calculation and design method for the longitudinal spacing of the heat supply pipe in the subgrade along the railway direction is as follows: On the basis of determining the burial depth of the heat supply pipe in the subgrade, using the heat influence radius calculation formula, as shown in formula (1), calculate the increasing law of the heat influence radius of the heat supply pipe in the subgrade with time. Take the R value corresponding to 2 days and 48 hours as the expected prevention and control range of a single heat supply pipe in the subgrade facing frost heaving diseases. Then, the longitudinal spacing between adjacent heat supply pipes in the subgrade is 2R. The calculation of the heat influence radius of the heat supply pipe is as follows:

[0137] (1)

[0138] In the formula, T0 is the outer wall temperature of the heat supply pipe, which is equal to the set value of the exhaust temperature of the compressor, °C; T f is the target temperature of the subgrade filler, generally taken as the freezing temperature of the filler, °C; T s is the lowest daily average temperature during the freezing period at the harmful freezing depth of the ordinary subgrade, °C; K s is the correction coefficient of the subgrade filler, taken as the compaction coefficient of the subgrade. That is, when the subgrade compaction is poor, the heat influence radius decreases accordingly; a is the thermal diffusivity of the filler, m 2 / h; τ is the time, h; H1 is the harmful freezing depth of the subgrade, m;

[0139] The calculation and design method for the length of the heat supply pipe body in the subgrade is as follows: On the basis of determining the burial depth of the heat supply pipe in the subgrade, calculate the length of the heat supply pipe. Referring to the standard gauge of 1.435 m of China's railways, the heat supply pipes on both sides are laid directly below the rails on both sides of the center of the railway line. The calculation of the length of the heat supply pipe is as follows:

[0140] (2)

[0141] In the formula, k is the width-height ratio of the subgrade slope; b is the shoulder width, m; B is the width of the ballast bed of a single-track railway or the width of the ballast bed of the up-line or down-line of a double-track railway, m;

[0142] Second, the calculation and design of the heating capacity of the heating unit;

[0143] The heating capacity of each heating unit is calculated as follows:

[0144] (3)

[0145] In the formula, λ1 is the surface convective heat transfer coefficient, W / (m 2 ·°C); h is the subgrade height, m; T a is the daily average temperature; ΔH is the growth rate of the freezing depth of the ordinary subgrade, m / s; ρ is the density of the subgrade filler, kg / m 3 ; c is the specific heat capacity of the subgrade filler, J / (kg·°C);

[0146] The third item is the calculation and design of the arrangement parameters of the heat collecting pipes in the foundation;

[0147] The method for determining the buried depth of the top of the heat carrier circulation pipeline of the ground heat collecting pipe is as follows: through on-site exploration and monitoring of the foundation near the frost heaving disease area of the subgrade, determine the maximum freezing depth of the foundation, which is the buried depth H2 of the top of the heat carrier circulation pipeline.

[0148] The calculation of the body height of the ground heat collecting pipe is as follows:

[0149] (4)

[0150] In the formula, H2 is the buried depth of the top of the heat carrier circulation pipeline, taking the maximum freezing depth of the natural ground surface, m; d is the equivalent heat absorption diameter of the stainless steel outer sleeve pipe for the ground temperature energy, m; λ2 is the heat transfer coefficient at the contact interface between the stainless steel outer sleeve pipe and the foundation soil, W / (m 2 ·°C); T e is the average temperature of the heat carrier circulation pipeline of the ground heat collecting pipe, °C; T g is the average ground temperature in the range below the maximum freezing depth of the foundation.

[0151] Start the ground source heat pump device and input the design parameters of the above-mentioned heating components on the control panel; power on the compressor to start, and at the same time open all the valves on the main circulation return path, while the valves on the second auxiliary branch of the compressor superheat rapid increase component and the third auxiliary branch of the compressor exhaust temperature equalization adjustment component remain closed.

[0152] 2) Perceive and display the measured values of the 2 temperature sensors arranged on the subgrade and the 2 displacement sensors arranged on the track at a fixed interval of 30 minutes.

[0153] 3) The PLC controller calculates the differential frost heave deformation amount of the track structure, that is, the amplitude of the unevenness of the track, and obtains the average temperature of the subgrade freezing depth and the harmful freezing depth range through linear interpolation of the subgrade temperature sensor.

[0154] 4) When the differential frost heave deformation is less than the management limit of track unevenness specified in the "General Speed Railway Line Repair Rules" (TG / GW 102) or the "High-Speed Railway Line Maintenance Rules" (National Railway Equipment Supervision Regulation

[2023] No. 15), it indicates that it is in the prevention stage of frost heave diseases; the operation mode control scheme of the ground source heat pump device is as follows:

[0155] According to the weather forecast and the measured data in step 2), the PLC controller calculates the required heating capacity at a fixed interval of 30 minutes; then the PLC controller calculates the required heat carrier flow rate and the corresponding throttle valve opening according to the required heating capacity (i.e., Q calculated by formula (3)).

[0156] The calculation method of the heat carrier flow rate is to divide the heating capacity required by a single heat pump by the phase change latent heat value of the heat carrier. The phase change latent heat of R134a is 215.6 kJ / kg. The calculation method of the throttle valve opening is the ratio of the heat carrier flow rate to the maximum allowable flow rate.

[0157] 5) When the differential frost heave deformation is greater than the management limit of track unevenness specified in the "General Speed Railway Line Repair Rules" (TG / GW 102) or the "High-Speed Railway Line Maintenance Rules" (National Railway Equipment Supervision Regulation

[2023] No. 15), it indicates that it has entered the post-disaster rapid rectification stage of frost heave diseases; the operation mode control scheme of the ground source heat pump device is as follows:

[0158] Open the throttle valve to 70% until the differential frost heave deformation of the track is reduced within the management limit, and then resume the operation mode in step 4).

[0159] The beneficial effects of the above design are: Select the compressor and fill the heat carrier according to the maximum load. Through the on-site measured results of the subgrade temperature and deformation, the throttle valve opening and the heat carrier flow rate can be flexibly adjusted for different subgrade frost heave disease sections or the disease degrees of the same frost heave disease section at different times, realizing the dynamic matching of the heat pump operation mode and the subgrade frost heave disease degree, and solving the problems of large heat overflow loss and high compressor energy consumption when the conventional control is solely based on the subgrade temperature.

[0160] In step 4), the operation mode of the ground source heat pump device is adjusted through the operating state of the compressor, and the control process and adjustment logic are:

[0161] 1) Perceive and display the 3 temperature sensors and 2 pressure sensors arranged in the heating unit at a fixed interval of 10 minutes;

[0162] 2) The PLC controller calculates 3 compressor evaluation indicators, including compression ratio, suction superheat degree, and discharge superheat degree;

[0163] 3) According to the compressor evaluation index, execute the control commands for the compressor superheat rapid increase component and the compressor exhaust temperature balance adjustment component. The specific scheme is as follows:

[0164] ① When the displayed suction superheat is lower than 5°C, the PLC controls the valve of the compressor superheat rapid increase component to open; ② When the displayed compression ratio is greater than 8, the PLC controls the electromagnetic flow valve of the compressor exhaust temperature balance adjustment component to perform jet enthalpy increase at a rate of 1 / 200 of the total refrigerant charge per minute; ③ When the displayed discharge superheat is greater than 20°C, the PLC controls the electromagnetic flow valve of the compressor exhaust temperature balance adjustment component to perform liquid injection cooling at a rate of 1 / 100 of the total refrigerant charge per minute. The operations in the second and third categories are prioritized by the third category. The above operations are adjusted for the opening and closing of the compressor superheat rapid increase component and the compressor exhaust temperature balance adjustment component at a fixed interval of 10 minutes according to the corresponding compressor operating state indicators.

[0165] The beneficial effect of this design is that it can accurately adjust the actions of each control valve according to the real-time state of the compressor, improve the problems of difficult establishment of suction superheat and long startup time in the startup stage of the compressor in a severe cold climate environment, as well as the problems of low gasification rate of the ground heat collecting pipe, small compressor return air volume, and high exhaust temperature in the normal operation stage, comprehensively improve the startup performance and operation performance of the compressor, and enhance the low-temperature heating performance.

[0166] Finally, it should be noted that the above are only the preferred embodiments of the present invention and are not used to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the scope of protection of the claims of the present invention.

Claims

1. A prevention and control system for frost heaving diseases of railway subgrades adapted to severe cold climates, characterized in that: The prevention and control system includes several groups of ground source heat pump devices arranged at intervals along the length direction of the railway subgrade. The ground source heat pump device includes a heating unit, a heat supply pipe, a heat collection pipe, and a detection component. The heat collection pipe is connected to the heat supply pipe through the heating unit. The heating unit is located on the surface of the foundation at the toe of the subgrade slope. The heat supply pipe is horizontally laid in the frost heave development layer of the subgrade. The heat collection pipe is located in the lower stable layer of the foundation on both sides of the subgrade. The detection component includes a temperature sensor, a pressure sensor, and a displacement sensor. Temperature sensors are provided in the subgrade, in the middle of the heat collection pipe, and on the pipeline of the heating unit, respectively, for monitoring the harmful freezing temperature of the subgrade and the temperature of the heat carrier in the pipeline. Pressure sensors are provided at the suction port and the discharge port of the compressor of the heating unit for monitoring the suction and discharge pressures of the compressor. The displacement sensor is arranged at the web of the railway track for detecting the deformation of the track. The heating unit, the temperature sensor, the pressure sensor, and the displacement sensor are all connected to the control component.

2. The prevention and control system for frost heaving diseases of railway subgrades adapted to severe cold climates according to claim 1, wherein: The heating unit includes a cabinet and a heating component. The heating component and the control component are both arranged in the cabinet. The heating component is connected to the heat supply pipe and the heat collection pipe through pipelines. The heating component can realize the condensation and liquefaction and the evaporation and gasification of the heat carrier, respectively for heating the subgrade and absorbing heat from the foundation. The heating component includes a compressor, a gas-liquid separator I, a liquid storage tank, a throttler, and a gas-liquid separator II. The discharge port of the compressor is connected to the inlet A of the electromagnetic three-way valve I. The outlet B of the electromagnetic three-way valve I is connected to the inlet of the heat supply pipe. The outlet of the heat supply pipe is connected to the inlet A of the gas-liquid separator I. The liquid outlet B of the gas-liquid separator I is connected to the inlet of the liquid storage tank. The outlet of the liquid storage tank is connected to the inlet A of the electromagnetic three-way valve II. The outlet B of the electromagnetic three-way valve II is connected to the inlet of the throttler. The outlet of the throttler is connected to the inlet of the heat collection pipe. The outlet of the heat collection pipe is connected to the inlet A of the gas-liquid separator II. The gas outlet C of the gas-liquid separator II is connected to the inlet A of the electromagnetic three-way valve III. The outlet B of the electromagnetic three-way valve III is connected to the inlet of the return pipe. The outlet of the return pipe is connected to the suction port of the compressor, forming the main circulation loop of the heat carrier. It also includes a mixing chamber. The gas outlet C of the gas-liquid separator I is connected to one inlet of the mixing chamber through a connecting pipe. The other inlet of the mixing chamber is connected to the liquid outlet B of the gas-liquid separator II through a connecting pipe. The outlet of the mixing chamber is connected to the pipeline between the gas-liquid separator II and the electromagnetic three-way valve III through a connecting pipe. A one-way valve is provided on each connecting pipe, forming the first auxiliary branch of the heat carrier. It also includes a compressor superheat rapid increase component, including a return pipe and a bypass pipe. The bypass pipe is provided with a heating sleeve on the outside. The inlet of the bypass pipe is connected to the auxiliary port C of the electromagnetic three-way valve I. The outlet of the bypass pipe is connected to the auxiliary port C of the electromagnetic three-way valve III, forming the second auxiliary branch of the heat carrier. It further includes a compressor exhaust temperature equalization and regulation component, which includes an electromagnetic flow valve and a capillary tube. The electromagnetic flow valve is arranged on the capillary tube. The inlet of the electromagnetic flow valve is connected to the auxiliary port C of the electromagnetic three-way valve II. The outlet of the electromagnetic flow valve is connected to the inlet of the capillary tube. The outlet of the capillary tube is connected to the heat carrier filling port of the compressor, forming a third auxiliary branch of the heat carrier.

3. The railway subgrade frost heave disease prevention and control system adapted to severe cold climate according to claim 2, characterized in that: The return air pipe is a copper pipe with an outer diameter of 10.0 mm, a wall thickness of 1.0 mm, and a length of 2.5 m. The return air pipe is spirally wound around the outer shell of the compressor; the bypass pipe is a copper pipe with an outer diameter of 16.0 mm and a wall thickness of 1.0 mm. The bypass pipe inside the heating jacket is spiral. The rated power of the heating jacket is 50 W, and the heating temperature is 40 °C; the capillary tube is a copper pipe with an outer diameter of 3.0 mm and a wall thickness of 0.5 mm. The length unit of the capillary tube is cm, and the value is 1 / 5 of the rated power of the compressor.

4. The prevention and control system for frost heaving diseases of railway subgrades adapted to severe cold climates according to claim 2, wherein: The control component includes a PLC controller and a control panel. The temperature sensor, pressure sensor, displacement sensor, throttle, electromagnetic three-way valve I, electromagnetic three-way valve II, electromagnetic three-way valve III, heating jacket, and electromagnetic flow valve are all connected to the PLC controller. The PLC controller, compressor, gas-liquid separator I, and gas-liquid separator II are all connected to the control panel.

5. A prevention and control system for frost heaving diseases of railway subgrades adapted to severe cold climates according to claim 2, characterized in that: The heat collecting tube includes a tube body and a protective cover at its end. The tube body consists of an outer sleeve tube and a base tube from outside to inside. The inner cavity of the base tube is filled with heat storage material. The outer surface of the base tube is spirally wound with a heat carrier circulation tube. Thermal conductive mortar is filled between the base tube and the outer sleeve tube. The heat carrier circulation tube is immersed in the thermal conductive mortar; The heating pipe and the heat collecting tube have the same structure.

6. The prevention and control system for frost heaving diseases of railway subgrades adapted to severe cold climates according to claim 5, characterized in that: The outer sleeve tube is a 201 stainless steel tube with an outer diameter of 114 mm and a wall thickness of 2 mm. The thermal conductive mortar is a metal-based thermal conductive mortar with a thermal conductivity of 2.0 - 2.5 W / (m·K); The heat carrier circulation tube is a copper pipe with an outer diameter of 6.0 mm and a wall thickness of 0.6 mm; the base tube is a wire mesh skeleton composite PVC pipe with an outer diameter of 75 mm; the heat storage material is silty soil or sandy soil with a moisture content of 20% - 30%; The heat carrier is a medium-high temperature heat carrier R134a. The filling amount unit of the heat carrier is g, and the value is 3.5 times the rated power of the compressor; The compressor is a fully enclosed single-stage piston compressor with a rated input power of 100 - 600 W; the gas-liquid separator I is a gravity sedimentation type separator, and the gas-liquid separator II is a baffle separation type separator; the liquid storage tank adopts an inverted conical tank body, and the throttle adopts an electronic expansion valve.

7. A prevention and control system for frost heaving diseases of railway subgrades adapted to severe cold climates according to claim 2, characterized in that: The cabinet includes a cabinet body and a base at its bottom. A switchable cabinet door is provided on the front side of the cabinet body. The interior is divided into 3 layers by two parallel trays in the middle. The two trays are the upper tray and the lower tray respectively; upper and lower shielding plates are vertically provided on the inner side of the cabinet door. Left and right windows are respectively provided on the left and right side walls of the cabinet body; The compressor, electromagnetic three-way valve I, electromagnetic three-way valve II, electromagnetic three-way valve III, liquid storage tank and mixing chamber are arranged on the upper support plate, and the bypass pipe, electromagnetic flow valve, capillary tube, gas-liquid separator I, throttle and gas-liquid separator II are arranged on the lower support plate; the control component is arranged on the upper cover plate.

8. A method for preventing and controlling the frost heaving disease of railway subgrade adapted to severe cold climate, characterized in that, It includes the following steps: 1) Assemble and install the prevention and control system as described in any one of claims 2-7, and design the layout parameters of the heat supply pipe and the heat collection pipe and the heat supply capacity of the heating unit; Start the ground source heat pump device and input the design parameters on the control panel of the control component; Start the compressor, simultaneously open the main circulation loop, and close the second auxiliary branch of the compressor superheat rapid increase component and the third auxiliary branch of the compressor exhaust temperature equalization adjustment component; 2) Regularly collect the measured values of the temperature sensors on the subgrade and the displacement sensors on the track at a fixed interval time t of 10-30 minutes; 3) Calculate the differential frost heave deformation amount of the track structure, that is, the vertical irregularity amplitude of the track, through the PLC controller of the control component, and obtain the average temperature of the subgrade freezing depth and the harmful freezing depth range according to the linear interpolation of the subgrade temperature sensor; 4) When the differential frost heave deformation amount is less than the specified track vertical irregularity management limit value, it indicates that it is in the prevention stage of frost heave diseases; the operation mode control scheme of the ground source heat pump device is as follows: According to the weather forecast and the measured data in step 2), at a fixed interval time t of 10-30 minutes, the PLC controller calculates the required heat supply capacity and obtains the required heat carrier flow rate and the corresponding throttle opening; The calculation method of the heat carrier flow rate is the heating power of a single heat pump divided by the phase change latent heat value of the heat carrier, and the calculation method of the throttle opening is the ratio of the heat carrier flow rate to the maximum allowable flow rate; 5) When the differential frost heave deformation amount is greater than the specified track vertical irregularity management limit value, it indicates that it has entered the rapid post-disaster remediation stage of frost heave diseases; the operation mode control scheme of the ground source heat pump device is as follows: Open the throttle to 70% until the differential frost heave deformation amount of the track is reduced to within the management limit value, and then resume the operation mode of step 4).

9. A method for preventing and controlling the frost heaving disease of railway subgrade adapted to severe cold climate according to claim 8, characterized in that: In step 4), the operation mode of the ground source heat pump device is adjusted through the operating state of the compressor, and the adjustment logic is as follows: 1) Sense and display the temperature sensors and pressure sensors arranged in the heating unit at a fixed interval of 10 minutes; 2) Calculate the evaluation indexes of the compressor by PLC control, including compression ratio, suction superheat and exhaust superheat; 3) According to the compressor evaluation indexes, execute the control commands for the compressor superheat rapid increase component and the compressor exhaust temperature equalization adjustment component, and the specific scheme is as follows: ① When the displayed suction superheat is lower than 5°C, the compressor superheat rapid increase component is controlled by PLC to open; ② When the displayed compression ratio is greater than 8, the compressor exhaust temperature equalization adjustment component is controlled by PLC to perform jet enthalpy increase at a rate of 1 / 200 of the total heat carrier charge per minute. ③When the displayed superheat of exhaust is greater than 20°C, the PLC controls the compressor exhaust temperature equalization adjustment component to perform liquid injection cooling at a rate of 1 / 100 of the total refrigerant charge per minute. The operations of the above steps ①, ②, and ③ are all at a fixed interval of 10 minutes, and the opening and closing of the compressor superheat rapid increase component and the compressor exhaust temperature equalization adjustment component are adjusted according to the corresponding compressor evaluation indicators.

10. A method for preventing and controlling the frost heaving disease of railway subgrade adapted to severe cold climate according to claim 8, characterized in that: In step 1), the longitudinal spacing of the heating pipes between adjacent roadbeds is 2R, and the thermal influence radius of the heating pipes is calculated as follows: （1） where, T0 is the outer wall temperature of the heating pipe, °C; T f is the target temperature of the subgrade filler, °C; T s is the lowest daily average temperature during the freezing period at the harmful freezing depth of the ordinary subgrade, °C; K s is the correction coefficient of the subgrade filler, taken as the compaction coefficient of the subgrade; a is the thermal diffusivity of the filler, m 2 / h; τ is the time, h; H1 is the harmful freezing depth of the subgrade, m; The gauge of the railway is taken as the standard gauge of 1.435 m. The heating pipes on both sides are laid directly below the rails on both sides of the railway line center. The length of the heating pipes is calculated as follows: （2） In the formula, k is the width-height ratio of the roadbed slope; b is the shoulder width, m; B is the width of the single-track railway ballast bed or the width of the single-track ballast bed of the double-track railway's up-line or down-line, m; The heating capacity of the heating unit is calculated as follows: （3） where λ1 is the ground surface convective heat transfer coefficient, W / (m 2 ·°C); h is the subgrade height, m; T a is the daily average temperature; ΔH is the growth rate of the freezing depth of the ordinary subgrade, m / s; ρ is the density of the subgrade filler, kg / m 3 ; c is the specific heat capacity of the subgrade filler, J / (kg·°C); The height of the heat collecting pipe is calculated as follows: （4） Wherein, H2 is the buried depth at the top of the heat carrier circulation pipeline, taking the maximum natural ground freezing depth, m; d is the equivalent heat absorption diameter of the stainless steel outer casing pipe for geothermal energy, m; λ2 is the heat transfer coefficient at the contact interface between the stainless steel outer casing pipe and the foundation soil, W / (m 2 ·°C); T e is the average temperature of the heat carrier circulation pipeline of the ground heat collector, °C; T g is the average ground temperature in the range below the maximum ground freezing depth.

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