A kind of anti-freeze pull-out pile foundation and construction method thereof

Abstract

The present invention provides a novel frost-resistant pull-out type pile foundation and a construction method thereof, belonging to the technical field of pile foundation engineering in frozen soil areas. The novel frost-resistant pull-out type pile foundation comprises a pile basic body, a geothermal energy conversion system and an intelligent operation control system. The pile basic body is divided into a geothermal energy collection section and a heating section from bottom to top along its height direction; the geothermal energy conversion system is used to extract geothermal energy located in the soil around the geothermal energy collection section and provide heat energy to the heating section; the intelligent operation control system is connected to the geothermal energy conversion system for communication and is used to control the temperature of the geothermal energy collection section and / or the heating section. Through the geothermal energy conversion system, geothermal energy is collected and converted into a high-grade heat source, and heat is actively transferred to the soil around the pile, and the temperature of the soil around the pile is strictly controlled to be above 0°C, fundamentally solving the problem of pile foundation freezing pull-out. The present invention is energy-saving and environmentally friendly, has low energy consumption, and high thermal quality. It also has a deep geothermal energy compensation function to maintain the long-term availability of geothermal energy.

Description

Technical Field

[0001] The invention belongs to the technical field of pile foundation engineering in frozen soil areas, and more specifically, relates to a freeze-resistant pull-out type pile foundation and a construction method thereof. Background Art

[0002] In the construction of infrastructure such as transportation, water conservancy, power transmission, oil and gas pipelines, pile foundations are a common foundation type for structures such as bridges, aqueducts, overhead pipelines, electric towers, and railway electrification columns. The frozen soil area in my country accounts for more than 70% of the land area. The seasonal freezing and melting of the shallow rock and soil around the pile foundation will cause the deterioration of the pile's bearing capacity and its own stability. Among them, frost pull is a typical disease of pile foundations. Field records show that the maximum annual frost pull of pile foundations in deep seasonal frozen soil areas can reach 10-20cm. After the pile foundation is frozen in winter, it cannot be completely pulled back during the spring thaw period. The accumulation year by year causes the pile foundation to arch and tilt, which in turn leads to deformation, fracture and collapse of the upper structure. Therefore, anti-freeze pull design is one of the key issues in pile foundation engineering in frozen soil areas.

[0003] The frozen pullout of the pile body is caused by the change in the relative relationship between the tangential frost heaving force and the pull-out bearing capacity (the sum of the upper load, the pile itself and the friction resistance on the pile side) and the freezing force. The tangential frost heaving force is the control condition for the stability of the pile foundation in deep seasonal freezing areas. The design of the pile foundation for anti-freeze pullout mainly includes two ways: weakening the frost heaving force of the frozen soil layer and increasing the anchoring force of the lower non-frozen soil layer. Among them, the methods for weakening the frost heaving force of the frozen soil layer include the frozen soil layer replacement method, waterproofing and drainage method, insulation method, pile foundation and foundation isolation method, and conical slope foundation method. The methods for increasing the anchoring force of the lower non-frozen soil layer include increasing the length of the straight pile, expanding the bottom pile method, variable diameter pile method, stepped foundation method, and screw pile method.

[0004] In the prior art, although the above-mentioned pile foundation anti-freeze pullout design method is adopted, it is impossible to achieve artificial control of the key disease background of foundation frost heave, and the anti-freeze pullout effect is not ideal. In severely cold and water-rich areas such as shallow underground levels, large freezing depths, and low atmospheric temperatures, the design of existing measures is difficult, and frost pullout diseases caused by pile foundation frost heave still exist. Summary of the invention

[0005] The object of the present invention is to provide a freeze-uplift resistant pile foundation and a construction method thereof, aiming to solve the technical problem of freeze-uplift damage of pile foundations in frozen soil areas caused by frost heaving of the foundation under cold and severe climate conditions.

[0006] To achieve the above object, the technical solution adopted by the present invention is to provide a freeze-resistant pull-out type pile foundation, comprising:

[0007] The pile basic body is divided into a geothermal energy collection section and a heating section from bottom to top along its height direction;

[0008] A geothermal energy conversion system, disposed on the geothermal energy collection section, the heating section and the ground surface, for extracting geothermal energy from the soil surrounding the geothermal energy collection section and providing heat energy to the heating section;

[0009] An intelligent operation control system is communicatively connected with the geothermal energy conversion system and is used to control the temperature of the geothermal energy collection section and the heating section.

[0010] In a possible implementation, the frost-resistant pile foundation further includes:

[0011] The heat storage and cold resistance system for the foundation around the pile is arranged inside the soil around the heating section, and is used to keep the soil foundation around the heating section warm so as to prevent the temperature of the soil foundation from dropping.

[0012] In a possible implementation, the pile basic body includes:

[0013] Steel cage;

[0014] The casing bracket is connected to the upper end of the steel cage, is in a circular shape, has an inner wall connected to the outer wall of the steel cage, and has a hook connected to the outer wall;

[0015] An inner sleeve is sleeved on the outside of the steel cage to surround the steel cage, the inner sleeve is located below the sleeve bracket, and the hook is used to connect with the inner sleeve;

[0016] Concrete is combined and fixedly connected with the steel cage.

[0017] In a possible implementation, the geothermal energy conversion system includes:

[0018] A U-shaped coil, coiled on the outer wall of the inner casing of the geothermal energy collection section, with an inlet and an outlet at both ends, and the U-shaped coil is used to contact the soil around the geothermal energy collection section and conduct heat;

[0019] A spiral coil is coiled on the outer wall of the inner sleeve of the heating section, with an inlet and an outlet at both ends, and the spiral coil is used to contact the soil around the heating section and conduct heat;

[0020] A refrigerant is filled in the U-shaped coil and the spiral coil;

[0021] A throttle valve, the input end of which is connected to the outlet of the spiral coil and the output end of which is connected to the inlet of the U-shaped coil, and the throttle valve is used to change the flow direction of the refrigerant;

[0022] A compressor, wherein the input end is connected to the outlet of the U-shaped coil and the output end is connected to the inlet of the spiral coil. The U-shaped coil, the spiral coil, the throttle valve and the compressor form a circulation loop of the refrigerant. The compressor is used to provide power for the circulation of the refrigerant. The U-shaped coil inhales the low-temperature and low-pressure refrigerant gas, and after being compressed by the compressor, the high-temperature and high-pressure refrigerant gas is pressed into the spiral coil to supply heat to the heating section.

[0023] In a possible implementation, the geothermal energy conversion system further includes:

[0024] A plurality of metal corrugated flexible connecting pipes, each of which is provided with a joint at both ends, and the outer wall of the middle portion is wrapped with heat-insulating cotton, and the compressor and the U-shaped coil, the compressor and the spiral coil, the throttle valve and the U-shaped coil, and the throttle valve and the spiral coil are all connected through the metal corrugated flexible connecting pipes;

[0025] The filter has two ends connected to the inlet and outlet of the spiral coil through the metal corrugated flexible connecting pipe, and is used to filter impurities in the refrigerant.

[0026] In a possible implementation, the compressor is connected to a protection box, which is used to fix the compressor and the throttle valve, and to insulate the compressor and the throttle valve from heat, cold, rain and wind.

[0027] In a possible implementation, the geothermal energy conversion system further includes:

[0028] The wind-solar complementary power generation system comprises an electric energy output terminal, wherein the electric energy output terminal is electrically connected to the compressor and is used to supply power to the compressor.

[0029] In a possible implementation, the intelligent operation control system includes:

[0030] A plurality of temperature sensors are respectively arranged inside the soil around the geothermal energy collection section, inside the soil around the heating section, on the ground surface and in the air, and are used to collect soil temperature, ground surface temperature and air temperature information at different positions;

[0031] A data collector, electrically connected to the plurality of temperature sensors, respectively, for receiving temperature data collected by the plurality of temperature sensors;

[0032] A microcomputer controller, electrically connected to the data collector and the compressor, for determining control of the compressor according to the received temperature information at different positions;

[0033] The remote automation control platform is connected to the microcomputer controller via wireless signals and is used for remotely controlling the operation of the microcomputer controller.

[0034] In a possible implementation, the pile surrounding foundation heat storage and cold resistance system includes:

[0035] A plurality of vertical insulation boards are arranged vertically, are arranged inside the soil around the heating section and are arranged around the heating section, and a gap is formed between the vertical insulation boards and the heating section;

[0036] A plurality of horizontal insulation boards are arranged horizontally, are arranged inside the soil around the heating section and are located at the upper ends of the plurality of vertical insulation boards, and the plurality of horizontal insulation boards are arranged around the heating section and form a surrounding structure for the heating section;

[0037] Filler, arranged around the outer periphery of the heating section and located inside the gap, forming a package for the heating section, the filler is located at the lower end of the horizontal insulation board, and the filler is coarse sand or gravel;

[0038] A plurality of phase-change heat storage capsules are arranged inside the filler and are used to reduce the heat transfer rate of the soil around the heating section and to increase the specific heat capacity.

[0039] The beneficial effect of a frost-resistant pile foundation provided by the present invention is that: compared with the prior art, the frost-resistant pile foundation of the present invention includes a pile basic body, a geothermal energy conversion system and an intelligent operation control system, and the pile basic body is divided into a geothermal energy collection section and a heating section from bottom to top along its height direction; the geothermal energy conversion system is arranged in the geothermal energy collection section, the heating section and the surface, and is used to extract the geothermal energy of the soil body around the geothermal energy collection section and provide heat energy to the heating section; the intelligent operation control system is connected to the geothermal energy conversion system and is used to control the temperature of the geothermal energy collection section and the heating section, and through the geothermal energy conversion system, the geothermal energy is collected and converted into a high-grade heat source, and heat is actively transferred to the soil body around the pile, and the temperature of the soil body around the pile is strictly controlled to be above 0°C, that is, the soil body is maintained in a non-frozen state, and the tangential frost heave force is directly and completely eliminated, and the pile foundation frost heave problem is fundamentally solved. At the same time, the present invention is energy-saving and environmentally friendly, has low energy consumption, and high thermal quality, and also has a deep geothermal energy compensation function to maintain the long-term availability of geothermal energy.

[0040] The present invention also provides a construction method for a freeze-resistant pull-out pile foundation, comprising the following steps:

[0041] Constructing a pile basic body so that the pile basic body is divided into a geothermal energy collection section and a heating section from bottom to top;

[0042] constructing a geothermal energy conversion system, so that it is arranged on the geothermal energy collection section, the heating section and the ground surface, so that it absorbs geothermal energy located in the soil around the geothermal energy collection section and provides heat energy to the heating section;

[0043] An intelligent operation control system is constructed so that it is connected to the geothermal energy conversion system for communication and is used to control the temperature of the geothermal energy collection section and the heating section.

[0044] The beneficial effect of a construction method of a frost-resistant and pull-out type pile foundation provided by the present invention is that: compared with the prior art, the construction method of a frost-resistant and pull-out type pile foundation provided by the present invention comprises sequentially constructing a pile basic body, a geothermal energy conversion system and an intelligent operation control system, wherein the pile basic body is sequentially divided into a geothermal energy collection section and a heating section along its height direction from bottom to top; the geothermal energy conversion system is arranged on the geothermal energy collection section, the heating section and the ground surface, and is used to extract geothermal energy located in the soil around the geothermal energy collection section and provide heat energy to the heating section; the intelligent operation control system is communicatively connected with the geothermal energy conversion system and is used to control the temperature of the geothermal energy collection section and the heating section, and through the geothermal energy conversion system, geothermal energy is collected and converted into a high-grade heat source, and heat is actively transferred to the soil around the pile, and the temperature of the soil around the pile is strictly controlled to be above 0°C, that is, the soil is maintained in a non-frozen state, and the tangential frost heave force is directly and completely eliminated, thereby fundamentally solving the freezing and pull-out problem of the pile foundation. At the same time, the present invention is energy-saving and environmentally friendly, has low energy consumption, high thermal quality, and also has the function of deep geothermal energy compensation, thereby maintaining the long-term availability of geothermal energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0046] Figure 1 A structural front view of a freeze-resistant pile foundation provided by an embodiment of the present invention;

[0047] Figure 2 A front view of a pile base structure of a freeze-resistant pile foundation provided by an embodiment of the present invention;

[0048] Figure 3 for Figure 2 A top view of a pile basic structure of a freeze-resistant pull-out type pile foundation provided in;

[0049] Figure 4 for Figure 2 A partial structural stereogram of a pile basic body of a freeze-resistant pull-out type pile foundation provided in;

[0050] Figure 5 for Figure 1 The structural front view of a geothermal energy conversion system and intelligent operation control system with a freeze-resistant pile foundation.

[0051] Description of reference numerals:

[0052] 1. Pile basic body; 11. Geothermal energy collection section; 12. Heating section; 13. Steel cage; 14. Casing support; 15. Inner casing; 16. Concrete;

[0053] 2. Geothermal energy conversion system; 21. U-shaped coil; 22. Spiral coil; 23. Throttle valve; 24. Compressor; 25. Metal corrugated flexible connecting pipe; 26. Filter; 27. Protection box; 28. Wind-solar hybrid power generation system;

[0054] 3. Intelligent operation control system; 31. Temperature sensor; 32. Data collector; 33. Microcomputer controller; 34. Remote automation control platform;

[0055] 4. Heat storage and cold resistance system of foundation around piles; 41. Vertical insulation board; 42. Horizontal insulation board; 43. Filler; 44. Phase change heat storage capsule. DETAILED DESCRIPTION

[0056] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0057] Please also read Figures 1 to 5 , now a freeze-pull-resistant pile foundation provided by the present invention is described. The freeze-pull-resistant pile foundation includes a pile basic body 1, a geothermal energy conversion system 2 and an intelligent operation control system 3. The pile basic body 1 is divided into a geothermal energy collection section 11 and a heating section 12 from bottom to top along its height direction; the geothermal energy conversion system 2 is arranged on the geothermal energy collection section 11, the heating section 12 and the ground surface, and is used to absorb the geothermal energy of the soil around the geothermal energy collection section 11 and provide heat energy to the heating section 12; the intelligent operation control system 3 is connected to the geothermal energy conversion system 2 for communication and is used to control the temperature of the geothermal energy collection section 11 and the heating section 12.

[0058] The present invention provides a frost-resistant pile foundation. Compared with the prior art, the pile base body 1 is divided into a geothermal energy collection section 11 and a heating section 12 from bottom to top along its height direction; the geothermal energy conversion system 2 is arranged on the geothermal energy collection section 11, the heating section 12 and the ground surface, and is used to extract the geothermal energy of the soil around the geothermal energy collection section 11 and provide heat energy to the heating section 12; the intelligent operation control system 3 is connected to the geothermal energy conversion system 2 and is used to control the temperature of the geothermal energy collection section 11 and the heating section 12. Through the geothermal energy conversion system 2, geothermal energy is collected and converted into a high-grade heat source, and heat is actively transferred to the soil around the pile, and the temperature of the soil around the pile is strictly controlled to be above 0°C, that is, the soil is maintained in a non-frozen state, and the tangential frost heave force is directly and completely eliminated, and the pile foundation frost heave problem is fundamentally solved. At the same time, the present invention is energy-saving and environmentally friendly, has low energy consumption, and high thermal quality, and also has a deep geothermal energy compensation function to maintain the long-term availability of geothermal energy.

[0059] The pile basic body 1 in this embodiment is divided into two sections, namely, a geothermal energy collection section 11 and a heating section 12. The pile basic body 1 is an improved structure based on the pile foundation in the prior art. The geothermal energy conversion system 2 can realize the extraction of geothermal energy and can supply heat to the heating section 12. The intelligent operation control system 3 can realize the control of the operation of the geothermal energy conversion system 2. The intelligent operation control system 3 can control the operation or conversion degree of the geothermal energy conversion system 2, and then control the temperature of the geothermal energy collection section 11 and the heating section 12 respectively.

[0060] Geothermal energy is heat energy generated and stored on the earth, which is the energy that determines the temperature of a substance. The lower part of the pile basic body 1 is placed within the range of geothermal energy, which can achieve energy transfer with geothermal energy. The above-mentioned communication connection can be connected by wireless communication connection in the prior art, such as GPRS, 4G, 5G and other communication connection methods.

[0061] The geothermal energy conversion system 2 is equivalent to the ground source heat pump system in the prior art, including a condenser (heat release function) and an evaporator (heat absorption function). The condenser is located in the pile heating section 12, and the evaporator is located in the geothermal energy collection section 11. The geothermal energy absorbed by the evaporator is conducted to the condenser, which can efficiently collect and improve the geothermal energy. Then, the heating section 12 is artificially and actively heated, so that the temperature of the pile basic body 1 is strictly controlled to be above 0°C in winter, that is, in a non-frozen state, thereby achieving the purpose of fundamentally eliminating the frost heave deformation of the foundation, the tangential frost heave force of the pile foundation, and the frost pullout phenomenon of the pile foundation. The anti-freeze pullout type pile foundation of the present invention collects geothermal energy and converts it into a high-grade artificial heat source through the geothermal energy conversion system 2, and artificially and actively transfers heat to the soil around the pile basic body 1, and strictly controls the temperature of the soil around the pile basic body 1 to be above 0°C, that is, the soil is maintained in a non-frozen state, and the tangential frost heave force is directly and completely eliminated, fundamentally solving the pile foundation frost pullout problem. At the same time, the new pile type is energy-saving and environmentally friendly, has low energy consumption, high thermal quality, and also has the function of deep geothermal energy compensation, maintaining the long-term availability of geothermal energy.

[0062] In some embodiments, see Figures 1 to 5 The frost-resistant pile foundation also includes a heat storage and cold-resistance system 4 around the pile foundation. The heat storage and cold-resistance system 4 around the pile foundation is arranged inside the soil around the heating section 12, and is used to keep the soil foundation around the heating section 12 warm, so as to prevent the temperature of the soil foundation from dropping. In addition to the above-mentioned geothermal energy conversion method to actively heat the soil around the pile base body 1, the use of the heat storage and cold-resistance system 4 around the pile foundation can achieve the insulation of the soil. The two methods cooperate with each other to strictly control the temperature of the pile base body 1 above 0°C in winter.

[0063] In some embodiments, see Figures 1 to 5 The pile basic body 1 includes a steel cage 13, a casing support 14, an inner casing 15 and concrete 16; the casing support 14 is connected to the upper end of the steel cage 13, is in a circular shape, and the inner wall is connected to the outer wall of the steel cage 13, and the outer wall is connected with a hook (not shown in the figure); the inner casing 15 is sleeved on the outside of the steel cage 13 and forms an enclosure for the steel cage 13, the inner casing 15 is located below the casing support 14, and the hook is used to connect with the inner casing 15; the concrete 16 is combined and fixedly connected with the steel cage 13. In this embodiment, the steel cage 13 adopts the existing technology product, and its manufacturing method, specifications, etc. can refer to the existing technology, which will not be described here. After the concrete 16 solidifies, it combines with the steel cage 13 to form an integral unit. The diameter of the inner casing 15 is between the inner diameter of the pile hole (pile diameter) and the outer diameter of the steel cage 13. Generally, the difference between the pile diameter and the diameter of the inner casing 15 is 10-15cm. The casing support 14 is set at the upper end of the steel cage 13, and a hook is set on the outer edge, and the hook is used to connect with the casing.

[0064] Specifically, the steel cage 13 includes longitudinal main bars and stirrups, which are designed and determined according to the standards or specifications related to pile foundations. The casing bracket 14 has an inner edge and an outer edge, and the outer edge and the inner edge are reinforced by steel bars. The concrete 16 determines the corresponding material ratio, vibration process, and strength according to the standards or specifications related to pile foundations.

[0065] In some embodiments, see Figures 1 to 5 The geothermal energy conversion system 2 includes a U-shaped coil 21, a spiral coil 22, a refrigerant, a throttle valve 23 and a compressor 24. The U-shaped coil 21 is coiled on the outer wall of the inner casing 15 of the geothermal energy collection section 11, and has an inlet and an outlet at both ends. The U-shaped coil 21 is used to contact the soil around the geothermal energy collection section 11 and is used for heat conduction; the spiral coil 22 is coiled on the outer wall of the inner casing 15 of the heating section 12, and has an inlet and an outlet at both ends. The spiral coil 22 is used to contact the soil around the heating section 12 and is used for heat conduction; the refrigerant is filled in the U-shaped coil 21 and the spiral coil 22; the throttle valve 23 outputs The inlet end is connected to the outlet of the spiral coil 22, and the output end is connected to the inlet of the U-shaped coil 21. The throttle valve 23 is used to change the flow direction of the refrigerant; the input end of the compressor 24 is connected to the outlet of the U-shaped coil 21, and the output end is connected to the inlet of the spiral coil 22. The U-shaped coil 21, the spiral coil 22, the throttle valve 23 and the compressor 24 form a circulation loop of the refrigerant. The compressor 24 is used to provide power for the circulation of the refrigerant. The U-shaped coil 21 inhales low-temperature and low-pressure refrigerant gas, which is compressed by the compressor 24 and then pressed into the spiral coil 22 with high-temperature and high-pressure refrigerant gas to provide heat to the heating section 12. In this embodiment, the U-shaped coil 21 is arranged in a U shape, and the spiral coil 22 is arranged in a spiral shape. Figure 1 As shown in . The U-shaped coil 21 and the spiral coil 22 are attached to the inner sleeve 15 and fixed by a semicircular buckle. The U-shaped coil 21 and the spiral coil 22 can be made of copper tube or aluminum tube, and the inner sleeve 15 can be made of PPE tube or thin-walled stainless steel tube. The inlet and outlet of the U-shaped coil 21 and the spiral coil 22 are equipped with flared joints, and both are fixed at the top of the inner sleeve 15.

[0066] Preferably, the throttle valve 23 is a four-way reversing valve, which functions to change the refrigerant flow direction, switch the pressure and working temperature of the geothermal energy collection section 11 and the heating section 12, and realize the heat compensation function of the geothermal energy conversion system 2 to the deep stable formation in summer. The compressor 24 adopts a closed piston compressor 24, which functions to provide power for the thermodynamic cycle of the geothermal energy conversion system 2, inhale low-temperature and low-pressure refrigerant gas from the geothermal energy collection section 11, and compress it through the operation of the motor of the compressor 24 to drive the piston to press the high-temperature and high-pressure refrigerant gas into the heating section 12 to realize artificial heating. Among them, the throttle valve 23 and the compressor 24 are arranged on the surface.

[0067] In some embodiments, see Figures 1 to 5 The geothermal energy conversion system 2 also includes a plurality of metal corrugated flexible connecting pipes 25 and a filter 26. The two ends of the plurality of metal corrugated flexible connecting pipes 25 are respectively equipped with joints, and the outer wall of the middle part is wrapped with thermal insulation cotton. The compressor 24 and the U-shaped coil 21, the compressor 24 and the spiral coil 22, the throttle valve 23 and the U-shaped coil 21, and the throttle valve 23 and the spiral coil 22 are all connected through the metal corrugated flexible connecting pipe 25; the two ends of the filter 26 are respectively connected to the inlet and outlet of the spiral coil 22 through the metal corrugated flexible connecting pipe 25, which is used to filter impurities in the refrigerant. The function of the filter 26 in this embodiment is to adsorb moisture and impurities in the refrigerant to prevent ice blockage and dirty blockage. The metal corrugated flexible connecting pipe 25 adopts the product in the prior art, which is a connecting pipe, with bell-mouth joints installed at both ends, and the middle pipe body is covered with thermal insulation cotton, which can realize the connection of the above-mentioned cycle. The heat insulation cotton adopts polyurethane direct buried heat insulation pipe, which has the function of heat insulation and cold insulation, preventing heat loss, and protecting the metal corrugated flexible connecting pipe 25 from soil pressure and water erosion. The two end joints of the metal corrugated flexible connecting pipe 25 are connected and sealed by double-butt lock nuts. The filter 26 can adopt existing technology products, or be a multi-stage filter 26.

[0068] Specifically, the refrigerant is a medium-temperature refrigerant, including R22 and R404A, and the heat absorption temperature is controlled between -5°C and 5°C to prevent the ground from frost heaving in the lower stratum of the pile basic body 1 and causing secondary frost pullout of the pile foundation.

[0069] In some embodiments, see Figures 1 to 5 The compressor 24 is connected to a protection box 27, which is used to fix the compressor 24 and the throttle valve 23, and to insulate the compressor 24 and the throttle valve 23 from heat and cold, and to protect them from rain and wind. The protection box 27 has the functions of heat and cold insulation, rain and wind protection, and prevents heat loss during the heat conversion process of the compressor 24. The connection method between the protection box 27 and the compressor 24 and the throttle valve 23 is not limited here.

[0070] In some embodiments, see Figures 1 to 5 The geothermal energy conversion system 2 also includes a wind-solar complementary power generation system 28, which has an electric energy output terminal, which is electrically connected to the compressor 24 and used to supply power to the compressor 24. In order to reduce the power supply of the city electricity to the compressor 24 and save energy, renewable energy is used, that is, the wind-solar complementary power generation system 28 is used to supply power to the compressor 24. The system can adopt existing technology and is composed of a wind turbine, a photovoltaic panel, a battery, and an inverter. The wind turbine and the photovoltaic panel generate direct current and store it in the battery. The inverter converts the direct current in the battery into alternating current and drives the compressor 24 to operate through the power supply wire. Among them, the battery and the inverter are fixed inside the system.

[0071] In some embodiments, see Figures 1 to 5 The intelligent operation control system 3 includes a plurality of temperature sensors 31, a data collector 32, a microcomputer controller 33 and a remote automation control platform 34. The plurality of temperature sensors 31 are respectively arranged inside the soil around the geothermal energy collection section 11, inside the soil around the heating section 12, on the ground surface and in the air, and are respectively used to collect soil temperature, ground surface temperature and air temperature information at different positions; the data collector 32 is respectively electrically connected to the plurality of temperature sensors 31, and is used to receive the temperature data collected by the plurality of temperature sensors 31; the microcomputer controller 33 is respectively electrically connected to the data collector 32 and the compressor 24, and is used to determine the control of the compressor 24 according to the received temperature information at different positions; the remote automation control platform 34 is connected to the microcomputer controller 33 by wireless signals, and is used to remotely control the operation of the microcomputer controller 33.

[0072] In this embodiment, the temperature sensors 31 located inside the soil around the heating section 12 are arranged at a vertical spacing of 0.3 meters, and the temperature sensors 31 located inside the soil around the geothermal energy collection section 11 are arranged at a vertical spacing of 0.5 meters. The number of temperature sensors 31 on the surface is one, and the number of temperature sensors 31 located in the air is one, which is located in the air and is used to detect the temperature in the air environment. It can be set on a wind turbine, such as Figure 1 As shown in . The temperature sensor 31 is a thermal resistor temperature sensor 31 with an accuracy of 0.1°C. The data collector 32 is an electronic device in the prior art, which is used to collect temperature signal data and can also realize signal transmission. The microcomputer controller 33 provides two operation control modes: (1) timed intermittent operation mode; (2) constant temperature operation mode, and the constant temperature reference standard is the average value of the temperature data collected by the temperature sensor 31 of the geothermal energy collection section 11. The microcomputer controller 33 has additional compressor 24 protection functions such as delayed start, high temperature shutdown protection, and low temperature start preheating. The remote automation control platform 34 controls the operation of the microcomputer controller 33 through the wireless communication connection method in the prior art, that is, sends instructions to the microcomputer controller 33 to preset the operation mode of the geothermal energy conversion system 2.

[0073] In some embodiments, see Figures 1 to 5The pile surrounding foundation heat storage and cold resistance system 4 includes a plurality of vertical insulation boards 41, a plurality of horizontal insulation boards 42, a filler 43 and a plurality of phase change heat storage capsules 44. The plurality of vertical insulation boards 41 are arranged vertically, are arranged inside the soil around the heating section 12 and are arranged around the heating section 12, and a gap is formed between the vertical insulation boards 41 and the heating section 12; the plurality of horizontal insulation boards 42 are arranged horizontally, are arranged inside the soil around the heating section 12 and are located between the plurality of vertical insulation boards. At the upper end of the temperature plate 41, a plurality of horizontal insulation plates 42 are arranged around the heating section 12 and form a surrounding structure for the heating section 12; a filler 43 is arranged around the outer periphery of the heating section 12 and is located inside the gap to form a wrapping for the heating section 12, and the filler 43 is located at the lower end of the horizontal insulation plate 42, and the filler 43 is coarse sand or gravel; a plurality of phase change thermal storage capsules 44 are arranged inside the filler 43, which are used to reduce the heat transfer rate of the soil around the heating section 12 and to increase the specific heat capacity.

[0074] Preferably, the vertical insulation board 41 adopts a vacuum insulation board with a thermal conductivity of 0.002 to 0.004 W / (m·K). The horizontal insulation board 42 adopts an extruded polystyrene insulation board (XPS board) with a thermal conductivity of 0.028 to 0.030 W / (m·K) and a compressive strength greater than 300 kPa. It has a certain bearing capacity to prevent damage by surface covering and other loads. The vertical insulation board 41 and the horizontal insulation board 42 are used as the insulation and cold-insulating boundaries of the artificial temperature control range around the pile basic body 1 (pile periphery). When the soil around the pile is frost-heaving sensitive fine-grained soil such as silt and silty clay, the soil within the artificial temperature control range around the pile is replaced with non-frost-heaving sensitive soil. When the artificial temperature control range around the pile is above the groundwater level, coarse sand or gravel is used; when the artificial temperature control range around the pile is partially or completely below the groundwater level, gravel must be used. When the soil around the pile is replaced with coarse sand or gravel, the specific heat capacity of the soil is low. When severe cold weather comes, the foundation cools down relatively quickly. At this time, a certain amount of phase change thermal storage capsules 44 are added. The phase change material inside the phase change thermal storage capsules 44 is paraffin, and the thermal conductivity of paraffin is 0.12W / (m·K). The phase change temperature is between 0 and 5°C, which can effectively reduce the heat transfer rate of the soil around the pile and increase the specific heat capacity, thereby enhancing the inertia and climate sensitivity of the soil around the pile.

[0075] Preferably, two adjacent vertical insulation boards 41 or horizontal insulation boards 42 are connected by snap-fit ​​connection. The volume ratio of the phase change thermal storage capsule 44 is 5% to 10%.

[0076] The frost-resistant pull-out pile foundation of the present invention has both mechanical bearing and thermal regulation functions. The pile base body 1 is a bored cast-in-place pile. It is determined according to the natural freezing depth and the geothermal energy resource conditions of the stable stratum of the foundation. The pile foundation can be a friction pile or an end-bearing pile. The mechanical bearing function and the geothermal energy conversion function do not interfere with each other. The geothermal energy conversion system 2 is essentially a special-shaped heat pump, which is a heat-raising device that efficiently utilizes low-grade thermal energy. The working principle of the heat pump is the reverse Carnot cycle. It consumes only a small amount of electrical energy and can efficiently extract 4 to 7 times the amount of electrical energy from the environmental medium (soil, etc.), which becomes a high-temperature heat source after system conversion. Due to the large temperature difference between the heat exchanger and the surrounding medium, the heat collection efficiency of the heat pump is much higher than the natural temperature difference heat transfer efficiency of the medium and the heat collection efficiency of the heat pipe. The heat pump has a low power consumption rate and can be driven and operated by an off-grid wind and solar power generation complementary system. It is controlled by a remote controller according to the established operation mode, has self-driving and automatic operation functions, and requires less manual maintenance.

[0077] In winter, when the temperature drops and the soil around the piles shows a tendency to frost heave, the geothermal energy conversion system 2 starts to operate, efficiently collects the geothermal energy of the non-frozen stable strata below the pile and improves its thermal grade, and then transfers it to the strata around the pile foundation, promptly compensating for the heat dissipation of the soil under the action of atmospheric air convection, preventing the soil temperature from dropping and the soil from freezing and expanding, thereby eradicating the frost heave phenomenon.

[0078] Beneficial effects: Through the geothermal energy conversion system 2, geothermal energy is collected and converted into high-grade artificial heat source, and heat is actively transferred to the soil around the pile, and the temperature of the soil around the pile is strictly controlled to be above 0°C, that is, the soil is maintained in a non-frozen state, and the tangential frost heave force is directly and completely eliminated, fundamentally solving the pile foundation freeze pull problem. At the same time, the new pile type (referring to the present invention) is energy-saving and environmentally friendly, has low energy consumption, high thermal quality, and also has the function of deep geothermal energy compensation, maintaining the long-term availability of geothermal energy.

[0079] The design method of the frost-resistant pull-out type pile foundation of the present invention is as follows:

[0080] The geothermal energy collection, conversion and transmission system embedded in the pile foundation does not affect the conventional bearing capacity design of the pile foundation. Therefore, the design of the pile foundation body 1 and the design of the geothermal energy collection, conversion and transmission system are carried out separately.

[0081] Step 1: First, according to the relevant design specifications of the pile foundation, combined with the pile top design load and foundation conditions, the pile foundation design is carried out, including pile diameter, pile length, steel cage 13 parameters, and concrete 16 grade.

[0082] Step 2: Determine the thermophysical parameters and initial temperature of frost heave strata and stable strata through indoor experiments and on-site thermal response tests, and calculate the earth's heat flux density and geothermal energy reserve level.

[0083] Step 3: Determine the temperature control range of artificial heating in the ground around the pile foundation.

[0084] The design standards are as follows: First, determine the increase rule of the radial heat diffusion radius of the pile foundation to the surrounding foundation over time under the condition of artificial heating of the pile foundation, and take the heat diffusion radius corresponding to one day of heating as the horizontal temperature control range; second, determine the maximum freezing depth of the foundation around the pile in winter, and the freezing depth is the vertical temperature control range, that is, the heat storage and cold resistance boundary. Third, the temperature control space range is replaced with coarse-grained soil filler that is not sensitive to frost heave 43.

[0085] Step 4: Based on climatic conditions, calculate the hourly heat load and maximum instantaneous heat load of the soil within the artificial temperature control range of the pile foundation.

[0086] The factors affecting heat load mainly include atmospheric temperature, atmospheric wind speed, solar irradiance, and terrain shielding. The target control temperature of the ground surface is 0℃, and the calculation method is as follows: first, the air convection heat exchange of the ground surface around the pile is calculated by combining the temperature control plane range around the pile, the hourly air temperature, and the comprehensive heat exchange coefficient of the ground surface; second, the surface radiation heat gain is calculated by combining the solar radiation heat conversion coefficient; third, the sum of the air convection heat exchange and the radiation heat gain is multiplied by the heat load coefficient, the hourly heat load time history curve is calculated, and the maximum instantaneous heat load is determined.

[0087] Step 5: Heat pump system design. The design standard for heating capacity is 1.5 times the maximum instantaneous heat load. According to the design heating capacity value, select the compressor 24 type and theoretical heating capacity.

[0088] Step 6: Select the diameter and material of the pipes used in the heat exchanger, and match the corresponding lengths of pipes for the heat collection section and the heating section 12, as well as the throttle valve 23 model, filter 26 model, and refrigerant filling amount according to the selected compressor 24 model exhaust volume.

[0089] Step 7: Determine the diameter of the inner casing 15 of the heating section 12 and the spacing between the spiral coils 22 according to the pile foundation diameter, freezing depth, and the length of the heating section 12 pipeline.

[0090] Step 8: Determine the spacing of the U-shaped coils 21 according to the depth of the pile foundation in the stable soil layer, the geothermal energy storage conditions of the stable stratum, and the length of the pipeline of the geothermal energy collection section 11.

[0091] Step 9: Design the operation control mode of the heat conversion system based on the hourly heat load of the soil around the pile foundation.

[0092] Step 10: Calculate the system power consumption according to the power consumption of the compressor 24 and the system operation control mode, and match the off-grid wind-solar complementary power generation system 28 with the corresponding power generation capacity.

[0093] The present invention also provides a construction method for a frost-resistant pull-out pile foundation, which comprises the following steps in sequence:

[0094] Constructing a pile basic body 1 so that the pile basic body 1 is divided into a geothermal energy collection section 11 and a heating section 12 from bottom to top;

[0095] Constructing a geothermal energy conversion system 2, so that it is arranged on the geothermal energy collection section 11, the heating section 12 and the ground surface, so that it absorbs geothermal energy in the soil around the geothermal energy collection section 11 and provides heat energy to the heating section 12;

[0096] An intelligent operation control system 3 is constructed so as to be communicatively connected with the geothermal energy conversion system 2 and used to control the temperature of the geothermal energy collection section 11 and the heating section 12 .

[0097] The beneficial effect of a construction method of a frost-resistant pull-out type pile foundation provided by the present invention is that: compared with the prior art, the construction method of a frost-resistant pull-out type pile foundation provided by the present invention comprises sequentially constructing a pile basic body 1, a geothermal energy conversion system 2 and an intelligent operation control system 3, wherein the pile basic body 1 is sequentially divided into a geothermal energy collection section 11 and a heating section 12 along its height direction from bottom to top; the geothermal energy conversion system 2 is arranged on the geothermal energy collection section 11, the heating section 12 and the ground surface, and is used to extract geothermal energy located in the soil around the geothermal energy collection section 11 and provide heat energy to the heating section 12; the intelligent operation control system 3 is communicatively connected with the geothermal energy conversion system 2 and is used to control the temperature of the geothermal energy collection section 11 and the heating section 12, and through the geothermal energy conversion system 2, geothermal energy is collected and converted into a high-grade heat source, and heat is actively transferred to the soil around the pile, and the temperature of the soil around the pile is strictly controlled to be above 0°C, that is, the soil is maintained in a non-frozen state, and the tangential frost heave force is directly and completely eliminated, thereby fundamentally solving the pile foundation freeze pull-out problem. At the same time, the present invention is energy-saving and environmentally friendly, has low energy consumption, high thermal quality, and also has the function of deep geothermal energy compensation, thereby maintaining the long-term availability of geothermal energy.

[0098] In some embodiments, the construction method is specifically as follows: the construction of the pile basic body 1 includes making a steel cage 13, making a geothermal energy collection section 11 and a heating section 12, etc. The specific structure can be found in the above description. The construction of the geothermal energy conversion system 2 includes making a heat exchanger, docking the metal corrugated flexible connecting pipe 25, and performing a sealing check. In the pressure test, the heat exchanger should be tight and leak-proof, and be able to withstand the vibration pressure of the pile foundation concrete 16 during the construction period and the working pressure of the heat pump. Those that fail to meet the requirements must be reinstalled until they meet the requirements. When making the pile basic body 1, the pile foundation is drilled (dug) and the mud wall is protected. The borehole deflection rate should not be greater than 0.5%. During the drilling process of the drilling rig, measuring instruments such as gyro inclinometers and orienteering instruments are used at any time to control and detect the quality of the borehole. When the steel cage 13 is placed, the concrete 16 is poured, the end of the metal corrugated flexible connecting pipe 25 is exposed and protected, and the concrete 16 is cured. After the concrete 16 is cured, a trench is dug around the pile foundation with a depth greater than 0.5 meters of freezing depth. The vertical insulation board 41 is buried, non-frost expansion soil is replaced, the horizontal insulation board 42 is arranged, and the temperature sensor 31 is arranged. The facilities located on the surface of the geothermal energy conversion system 2 are installed. The wind-solar hybrid power generation system 28 is installed and electrified. The heat pump system is evacuated and filled with refrigerant. Finally, the system is debugged and tested.

[0099] The operation control modes of the freeze-resistant pull-out pile foundation of the present invention are:

[0100] Control mode of anti-freeze pull function:

[0101] 1) In winter, from a preventive perspective, when the foundation around the piles begins to freeze, the ON / OFF timed intermittent operation mode is adopted, with a start-stop cycle of 3 hours and a unit duration of 0.5 hours. The operation control principle of the heat pump is:

[0102] When the heat load is 0% to 20% of the maximum heat load, the start-stop time ratio is set to 0.5h:2.5h.

[0103] When the heat load is 20% to 40% of the maximum heat load, the start-stop time ratio is set to 1.0h:2.0h.

[0104] When the heat load is 40% to 60% of the maximum heat load, the start-stop time ratio is set to 1.5h:1.5h.

[0105] When the heat load is 60% to 80% of the maximum heat load, the start-stop time ratio is set to 2.0h:1.0h.

[0106] When the heat load is 80% to 100% of the maximum heat load, the start-stop time ratio is set to 2.5h:0.5h.

[0107] 2) When the weather forecast predicts extremely low temperatures, the system should be set to continuous operation mode from the perspective of post-disaster emergency rescue.

[0108] 3) According to the temperature monitoring results, when negative temperature appears in the freezing depth range of the upper part of the pile, the geothermal energy conversion system 2 adopts the continuous operation mode to quickly supply heat to the soil around the pile to thaw.

[0109] 4) According to the temperature monitoring results, when the soil around the stable stratum under the pile body has negative temperature, it is set to the constant temperature operation mode, that is, when the boundary temperature of the geothermal energy collection section 11 is lower than 0°C, the geothermal energy conversion system 2 is shut down to prevent the pile foundation stable stratum from freezing and heaving to generate tangential freezing and heaving force, causing secondary disasters. After the ground temperature is restored to positive temperature by the surrounding geothermal heat flow, the thermal energy conversion system is restarted.

[0110] Control mode of foundation heating function:

[0111] In summer, June and July, when the atmospheric temperature is high, the heat exchanger on the upper part of the pile foundation is turned into an evaporator and the heat exchanger on the lower part of the pile foundation is turned into a condenser through the four-way reversing valve. The heat pump operation control mode is set to 2.0h:1.0h, which accelerates the transfer of shallow geothermal energy to deep stable formations and increases the temperature level of deep stable formations before winter. At the same time, the temperature of the shallow formation can be naturally replenished and restored in August.

[0112] The beneficial effects of the present invention are:

[0113] (1) The present invention has the dual functions of mechanical bearing and thermal regulation. Without affecting the bearing performance, it can efficiently collect geothermal energy from the stable stratum below the pile foundation and convert it into an artificial heat source to heat the stratum above the pile foundation, strictly controlling the heat balance and temperature change of the stratum above the pile body. Compared with the existing anti-freeze pull measures that can only passively weaken the frost heave force or increase the anchoring force, the pile base body 1 can actively maintain the temperature of the soil around the pile at above 0°C, that is, in a non-frozen state, fundamentally eliminating the tangential frost heave force, thereby solving the problem of pile body frost pull, which is more proactive and effective.

[0114] (2) Geothermal energy conversion system 2 is a special-shaped heat pump specially designed for bored piles. The heat pump adopts direct expansion heat exchange mode, and the refrigerant directly exchanges heat with the pile body. The heat exchange temperature difference is large, the geothermal energy collection efficiency is high, the heat source heating temperature is high, the heating coefficient is large, and the energy consumption is low. Geothermal energy conversion system 2 is driven and operated by a small off-grid wind-solar complementary power generation system 28. The power generation system is green and low-carbon, and the entire system is completely driven by renewable energy. After being put into operation, it can realize self-driving operation independently without manual supervision. Geothermal energy conversion system 2 is a closed circulation system, which is not affected by various harsh environmental conditions such as external atmospheric temperature, humidity, foundation moisture content, etc. It has a long service life, good durability, and low maintenance workload.

[0115] (3) The geothermal energy conversion system 2 is jointly controlled by a microcomputer controller 33 and a remote automation control platform 34. The microcomputer controller 33 can preset the system operation control mode, and can intelligently calculate the heat load based on the measured temperature data of the foundation around the piles, and adjust the operation mode of the geothermal energy conversion system 2 accordingly. At the same time, the remote automation control platform 34 can remotely operate the operation of the geothermal energy conversion system 2 based on weather forecasts, on-site emergencies, etc. The geothermal energy conversion system 2 has remote automation monitoring, intelligent decision-making functions, safety warning and emergency response functions.

[0116] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A frost-resistant pull-out pile foundation, characterized in that: include: The pile basic body is divided into a geothermal energy collection section and a heating section from bottom to top along its height direction; A geothermal energy conversion system, disposed on the geothermal energy collection section, the heating section and the ground surface, for extracting geothermal energy from the soil surrounding the geothermal energy collection section and providing heat energy to the heating section; An intelligent operation control system, which is in communication with the geothermal energy conversion system and is used to control the temperature of the geothermal energy collection section and the heating section; Also includes: The pile surrounding foundation heat storage and cold resistance system is arranged inside the soil surrounding the heating section and is used to keep the soil foundation surrounding the heating section warm to prevent the soil foundation temperature from dropping; The pile basic body comprises: Steel cage; The casing bracket is connected to the upper end of the steel cage, is in a circular shape, has an inner wall connected to the outer wall of the steel cage, and has a hook connected to the outer wall; The inner sleeve is made of a PPE tube or a thin-walled stainless steel tube, which is sleeved outside the steel cage and surrounds the steel cage. The difference between the diameter of the inner sleeve and the diameter of the pile foundation is 10-15 cm. The inner sleeve is located below the sleeve bracket, and the hook is used to connect with the inner sleeve; Concrete, fixedly connected to the steel cage assembly; The geothermal energy conversion system comprises: A U-shaped coil, coiled on the outer wall of the inner casing of the geothermal energy collection section, with an inlet and an outlet at both ends, and the U-shaped coil is used to contact the soil around the geothermal energy collection section and conduct heat; A spiral coil is coiled on the outer wall of the inner sleeve of the heating section, with an inlet and an outlet at both ends, and the spiral coil is used to contact the soil around the heating section and conduct heat; The refrigerant adopts a medium-temperature refrigerant, the heat absorption temperature of which is controlled between -5 and 5°C, and is filled inside the U-shaped coil and the spiral coil; The throttle valve adopts a four-way reversing valve, the input end of which is connected to the outlet of the spiral coil and the output end of which is connected to the inlet of the U-shaped coil. The four-way reversing valve is used to change the flow direction of the refrigerant when the geothermal energy conversion system compensates heat to the deep stable formation in summer; A compressor, the input end of which is connected to the outlet of the U-shaped coil and the output end of which is connected to the inlet of the spiral coil. The U-shaped coil, the spiral coil, the throttle valve and the compressor form a circulation loop of the refrigerant. The compressor is used to provide power for the circulation of the refrigerant. The U-shaped coil inhales the low-temperature and low-pressure refrigerant gas, and after being compressed by the compressor, the high-temperature and high-pressure refrigerant gas is pressed into the spiral coil to supply heat to the heating section. The intelligent operation control system comprises: A plurality of temperature sensors are respectively arranged inside the soil around the geothermal energy collection section, inside the soil around the heating section, on the ground surface and in the air, and are used to collect soil temperature, ground surface temperature and air temperature information at different positions; A data collector, electrically connected to the plurality of temperature sensors, respectively, and used for receiving temperature data collected by the plurality of temperature sensors; A microcomputer controller is electrically connected to the data collector and the compressor, respectively, and is used to determine the control of the compressor according to the received temperature information at different positions; the microcomputer controller provides two operation control modes: a timed intermittent operation mode and a constant temperature operation mode, and the constant temperature reference standard is the average value of the temperature data collected by the temperature sensor of the geothermal energy collection section; A remote automation control platform, connected to the microcomputer controller by wireless signals, for remotely controlling the operation of the microcomputer controller; Control mode of anti-freeze pull function: 1) In winter, from a preventive perspective, when the foundation around the piles begins to freeze, the ON / OFF timed intermittent operation mode is adopted, with a start-stop cycle of 3 hours and a unit duration of 0.5 hours; the operation control principle of the heat pump is: When the heat load is 0% to 20% of the maximum heat load, the start-stop time ratio is set to 0.5h:2.5h; When the heat load is 20% to 40% of the maximum heat load, the start-stop time ratio is set to 1.0h:2.0h; When the heat load is 40% to 60% of the maximum heat load, the start-stop time ratio is set to 1.5h:1.5h; When the heat load is 60% to 80% of the maximum heat load, the start-stop time ratio is set to 2.0h:1.0h; When the heat load is 80% to 100% of the maximum heat load, the start-stop time ratio is set to 2.5h:0.5h; 2) When the weather forecast predicts extremely low temperatures, the system should be set to continuous operation mode from the perspective of post-disaster emergency rescue; 3) According to the temperature monitoring results, when negative temperature appears in the freezing depth range of the upper part of the pile, the geothermal energy conversion system adopts the continuous operation mode to quickly supply heat to the soil around the pile to thaw; 4) According to the temperature monitoring results, when the soil around the stable stratum under the pile body has negative temperature, it is set to the constant temperature operation mode, that is, when the boundary temperature of the geothermal energy collection section is lower than 0℃, the geothermal energy conversion system is shut down to prevent the frost heave of the stable stratum of the pile foundation from generating tangential frost heave force and causing secondary disasters; after the ground temperature is restored to positive temperature by the surrounding geothermal heat flow, the thermal energy conversion system is restarted; Control mode of foundation heating function: In summer, in June and July, when the atmospheric temperature is high, the heat exchanger on the upper part of the pile foundation is converted into an evaporator and the heat exchanger on the lower part of the pile foundation is converted into a condenser through a four-way reversing valve; the heat pump operation control mode is set to 2.0h:1.0h, which accelerates the transfer of shallow geothermal energy to deep stable formations and increases the temperature level of deep stable formations before winter; at the same time, the temperature of the shallow formation can be naturally replenished and restored in August; The pile surrounding foundation heat storage and cold resistance system comprises: A plurality of vertical insulation boards, which are vacuum insulation boards, are arranged vertically, are arranged inside the soil around the heating section and are arranged around the heating section, and a gap is formed between the vertical insulation boards and the heating section; A plurality of horizontal insulation boards, which are extruded polystyrene insulation boards, are arranged horizontally, are arranged inside the soil around the heating section and are located at the upper ends of the plurality of vertical insulation boards, and the plurality of horizontal insulation boards are arranged around the heating section and form a surrounding structure for the heating section; Filler, arranged around the outer periphery of the heating section and located inside the gap, forming a package for the heating section, the filler is located at the lower end of the horizontal insulation board, and the filler is coarse sand or gravel; A plurality of phase-change heat storage capsules, the internal phase-change material of which is paraffin, the thermal conductivity of paraffin is 0.12W / (m·K), the phase-change temperature is between 0 and 5°C, and they are arranged inside the filler to reduce the heat transfer rate of the soil around the heating section and to increase the specific heat capacity. The volume proportion of the phase-change heat storage capsules is 5% to 10%.

2. A freeze-resistant pile foundation as claimed in claim 1, characterized in that: The geothermal energy conversion system further comprises: A plurality of metal corrugated flexible connecting pipes, each of which is provided with a joint at both ends, and the outer wall of the middle portion is wrapped with heat-insulating cotton, and the compressor and the U-shaped coil, the compressor and the spiral coil, the throttle valve and the U-shaped coil, and the throttle valve and the spiral coil are all connected through the metal corrugated flexible connecting pipes; The filter has two ends connected to the inlet and outlet of the spiral coil through the metal corrugated flexible connecting pipe, and is used to filter impurities in the refrigerant.

3. A freeze-resistant pile foundation as claimed in claim 1, characterized in that: The compressor is connected to a protection box, which is used to fix the compressor and the throttle valve, and to insulate the compressor and the throttle valve from heat, cold, rain and wind.

4. A freeze-resistant pile foundation as claimed in claim 1, characterized in that: The geothermal energy conversion system further comprises: The wind-solar complementary power generation system comprises an electric energy output terminal, wherein the electric energy output terminal is electrically connected to the compressor and is used to supply power to the compressor.

5. A construction method for a freeze-resistant pull-out pile foundation as claimed in any one of claims 1 to 4, characterized in that: The following steps are involved: Constructing a pile basic body so that the pile basic body is divided into a geothermal energy collection section and a heating section from bottom to top; constructing a geothermal energy conversion system, so that it is arranged on the geothermal energy collection section, the heating section and the ground surface, so that it absorbs geothermal energy located in the soil around the geothermal energy collection section and provides heat energy to the heating section; An intelligent operation control system is constructed so that it is connected to the geothermal energy conversion system for communication and is used to control the temperature of the geothermal energy collection section and the heating section.

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