Pile foundation in permafrost region and construction method thereof

Abstract

The invention discloses a permafrost region pile foundation and a construction method thereof, and relates to the technical field of permafrost region construction.The permafrost region pile foundation is characterized in that a reinforcement cage is arranged in a cast-in-place pile body, and the reinforcement cage and the cast-in-place pile body are coaxially arranged; the first temperature control structure is arranged at one end in the reinforcement cage, the first temperature control structure comprises a plurality of first pipe bodies, the two ends of each first pipe body are fixed to the reinforcement cage, the central axis of each first pipe body is perpendicular to the central axis of the reinforcement cage, and the first pipe bodies are filled with n-hexadecane; the second temperature control structure is arranged at the other end in the reinforcement cage, the second temperature control structure comprises a plurality of second pipe bodies, the two ends of the second pipe bodies are fixed to the reinforcement cage, the central axis of the second pipe bodies is perpendicular to the central axis of the reinforcement cage, and the second pipe bodies are filled with n-tetradecane. The method has the advantages that structural damage caused by frozen soil layer collapse due to temperature influence can be avoided, and structural safety is guaranteed.

Description

Technical Field

[0001] The present invention relates to the technical field of permafrost region construction, and in particular to a permafrost region pile foundation and a construction method thereof. Background Art

[0002] China's permafrost area is an important geographical feature. In recent years, with the development of my country's social economy and national conditions, the construction level of railways, transportation, housing and other construction projects in permafrost areas has gradually improved, and with more stringent ecological and environmental protection requirements, the "bridge instead of road" design model has been widely adopted. This model replaces traditional roadbeds with bridges, thereby reducing direct interference with the ground and protecting the stability of the permafrost.

[0003] The design and construction of pile foundations is a critical issue when carrying out construction projects in permafrost areas. Bored and cast-in-place piles are a common pile foundation design and construction method. They form pile foundations by drilling holes underground and pouring concrete to support the superstructure. However, during the warm season, solar radiation intensity increases significantly, and due to the broader trend of global warming, a large amount of heat is transferred into the permafrost through the pile foundations. Over time, this heat accumulates, causing the permafrost layer to gradually increase in temperature. The permafrost layer is originally frozen and relatively stable, but the heat transferred into the permafrost by the pile foundations has a significant cumulative effect. When the temperature rises to a certain level, the permafrost begins to thaw, which can lead to long-term thaw creep in the pile foundations, causing permafrost collapse, structural damage, and ultimately, building instability.

[0004] In summary, a pile foundation is needed that can avoid affecting the frozen soil structure. Summary of the Invention

[0005] In order to solve the above technical problems, the present invention provides a pile foundation in permafrost areas and a construction method thereof, which can avoid structural damage caused by permafrost collapse due to temperature influence and ensure structural safety.

[0006] The present invention provides a permafrost region pile foundation, comprising: A cast-in-place pile body, wherein a steel cage is provided therein, and the steel cage is coaxially arranged with the cast-in-place pile body; a first temperature control structure disposed at one end of the steel cage, the first temperature control structure comprising a plurality of first tubes, both ends of the plurality of first tubes being fixed to the steel cage, the central axis of the first tubes being perpendicular to the central axis of the steel cage, and the first tubes being filled with n-hexadecane; The second temperature control structure is arranged at the other end of the steel cage. The second temperature control structure includes a plurality of second tube bodies. Both ends of the plurality of second tube bodies are fixed to the steel cage, and the central axis of the second tube body is perpendicular to the central axis of the steel cage. The second tube body is filled with n-tetradecane.

[0007] Preferably, the volumes of n-hexadecane filled in the plurality of first tubes are equal, and the volumes of n-tetradecane filled in the plurality of second tubes are equal.

[0008] Preferably, the plurality of first tube bodies and the plurality of second tube bodies are distributed in the steel cage in a rectangular array.

[0009] Preferably, both ends of the plurality of first tubes and the plurality of second tubes are provided with sealing members, and the sealing members include: a set screw threadedly connected to the ends of the first tube body and the second tube body; a washer, disposed between the set screw and the end of the first tube body, and between the set screw and the end of the second tube body; A connecting ring is provided on the set screw.

[0010] Preferably, the first tube body and the second tube body are both steel pipes, and the outer walls of the steel pipes are coated with an epoxy coal tar anti-corrosion layer.

[0011] Preferably, it further comprises: a detection structure, which is arranged in the steel cage, and the detection structure comprises: A plurality of temperature measuring probes are evenly arranged in the steel cage, and the plurality of temperature measuring probes are used to detect the temperature of the cast-in-place pile body; The controller is electrically connected to the plurality of temperature measuring probes, and is used to receive temperature signals detected by the temperature measuring probes and determine the working states of the first temperature control structure and the second temperature control structure according to the temperature signals.

[0012] A method for constructing a pile foundation in a permafrost region, using a pile foundation in a permafrost region, comprises the following steps: Drill holes on the pile positions according to design requirements; performing sealing processing on one end of the plurality of first tubes and the plurality of second tubes; Filling n-hexadecane into the first tube bodies, filling n-tetradecane into the second tube bodies, and then sealing the other ends of the first tube bodies and the second tube bodies; Installing the sealed first tube bodies and the second tube bodies in the steel cage; The steel cage is lowered into the drilled hole and then concrete is poured.

[0013] Preferably, a plurality of the first tube bodies and a plurality of the second tube bodies are tied to the steel cage after passing steel wire through the connecting ring.

[0014] Preferably, the plurality of first tubes filled with n-hexadecane are installed in a rectangular array on the steel cage at the junction of the seasonal frozen soil layer and the ground; the plurality of second tubes filled with n-tetradecane are installed in a rectangular array on the steel cage at the junction of the seasonal frozen soil layer and the permafrost layer.

[0015] Preferably, sealing the ends of the first tube body and the second tube body by the sealing member includes the following steps: Wipe dry the connection between the first tube body, the second tube body and the set screw; Fix the washer and tighten the set screw; Structural adhesive is applied along the interfaces between the first tube body, the second tube body and the set screw.

[0016] Compared with the prior art, the present invention discloses a pile foundation in permafrost areas and a construction method thereof, which has the following beneficial effects: This pile foundation can avoid structural damage caused by the collapse of the permafrost layer due to temperature influences, and ensure structural safety. Specifically, heat is transferred to the permafrost layer by setting a first temperature control structure and a second temperature control structure in the steel cage. Phase change materials are filled in the first and second tubes. The phase change materials can absorb and release heat at specific temperatures. Through this characteristic, the heat input and thermal disturbance of the bored pile to the permafrost can be slowed down, thereby ensuring the long-term thermal stability of the pile foundation in the permafrost area. It can not only improve the thermal stability of the pile foundation and reduce the settlement and deformation caused by temperature changes, but also ensure the safety and stability of the building. It has important practical application value for engineering construction in permafrost areas. Moreover, when the first and second tubes are used horizontally, the phase change material can be evenly distributed laterally, ensuring that heat is evenly absorbed and released in different parts of the pile, avoiding local overheating or overcooling, controlling thermal disturbances, and achieving dynamic thermal balance. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. 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 any creative work.

[0018] Figure 1 It is a cross-sectional view of the pile foundation of the present invention.

[0019] Figure 2It is a structural schematic diagram of the pile foundation of the present invention.

[0020] Figure 3 This is a schematic structural diagram of the first tube body of the pile foundation of the present invention.

[0021] Figure 4 Schematic diagram showing comparison of heat transfer rates of the pile foundation of the present invention.

[0022] The meaning of each number in the figure is: 1—cast-in-place pile body, 2—reinforcement cage, 3—first pipe body, 4—seal, 5—n-tetradecane, 6—n-hexadecane, 7—temperature probe, 8—wire, 9—controller, 10—concrete, 11—connecting ring, 12—set screw, 13—washer. DETAILED DESCRIPTION

[0023] A specific embodiment of the present invention is described in detail below with reference to the accompanying drawings, but it should be understood that the protection scope of the present invention is not limited by the specific embodiment.

[0024] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "axial", "radial", "circumferential", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the technical solution of the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention.

[0025] In the description of the present invention, it should be noted that, unless otherwise specified or limited, the term "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be internal communication between two components. For those skilled in the art, the specific meanings of the above terms in this application can be understood by those skilled in the art in specific circumstances.

[0026] Additionally, in the description of the present invention, "plurality" refers to two or more than two. The terms "first" and "second" are used for descriptive purposes only and should not be understood to imply or suggest relative importance or implicitly indicate the number of technical features indicated. Therefore, features specified as "first" or "second" may explicitly or implicitly include one or more of the features.

[0027] Example 1 The embodiment of the present invention provides a pile foundation in permafrost area. Figure 1 、 Figure 2As shown, it includes: a cast-in-place pile body 1, a steel cage 2, a first temperature control structure, and a second temperature control structure. A steel cage 2 is provided in the cast-in-place pile body 1, and the steel cage 2 is coaxially arranged with the cast-in-place pile body 1. When in use, the steel cage 2 is a cylindrical vertical setting. After the steel cage 2 is poured with concrete 10, the cast-in-place pile body 1 is formed; the first temperature control structure is provided in the steel cage 2, and the first temperature control structure is located at the junction of the seasonal frozen soil layer and the ground when in use, that is, it is located at one end of the steel cage 2 close to the ground when in use, and exchanges heat with the junction of the seasonal frozen soil layer and the ground. The first temperature control structure includes a plurality of first tube bodies 3, and the two ends of the plurality of first tube bodies 3 are fixed to the steel cage 2, and the central axis of the first tube body 3 is perpendicular to the central axis of the steel cage 2, that is, the first tube body 3 is horizontally arranged when in use, as shown in FIG. Figure 2 As shown, the first tube body 3 is filled with a phase change material n-hexadecane 6, and the phase change temperature of the phase change material n-hexadecane 6 is about 18 ° C. It is suitable for the junction of the seasonal frozen soil layer and the ground. In the warm season, it absorbs heat near the ground and slows down the transfer of heat to the lower part of the pile foundation; the second temperature control structure is arranged in the steel cage 2. When in use, the second temperature control structure is located at the junction of the seasonal frozen soil layer and the permafrost layer, that is, when in use, it is located at the end of the steel cage 2 away from the ground, and exchanges heat at the junction of the seasonal frozen soil layer and the permafrost layer. The second temperature control structure includes a plurality of second tube bodies, and the two ends of the plurality of second tube bodies are fixed to the steel cage 2, and the central axis of the second tube body is perpendicular to the central axis of the steel cage 2, that is, the second tube body is horizontally arranged when in use. The second tube body is filled with a phase change material n-tetradecane 5, and the phase change temperature of the phase change material n-tetradecane 5 is about 5.5 ° C. It is suitable for the junction of the seasonal frozen soil layer and the permafrost layer, releases heat in the cold season, prevents the permafrost layer from overcooling, and reduces the risk of frost heave. N-hexadecane 6 and n-tetradecane 5 can cover the temperature control requirements of the pile foundation under different depths and temperature conditions. In this embodiment, the first tube body 3 and the second tube body are filled with phase change materials. Phase change materials refer to substances that change shape with temperature and can provide latent heat. In the warm season, the phase change heat absorption process of the phase change material is used to slow down the heat input and thermal disturbance of the bored pile to the permafrost, which can avoid structural damage caused by the collapse of the permafrost layer due to temperature influence and ensure structural safety. At the same time, the first tube body 3 and the second tube body are both arranged horizontally, so that the phase change material can be evenly distributed laterally, ensuring that heat is evenly absorbed and released in different parts of the bored pile body 1, avoiding local overheating or overcooling, performing thermal disturbance control, and achieving dynamic heat balance.

[0028] In the warm season, the phase change heat absorption process of the phase change material is utilized to slow down the heat input and thermal disturbance of the bored pile to the permafrost, thereby avoiding structural damage caused by the collapse of the frozen soil layer due to temperature influence, and ensuring structural safety. Moreover, the first tube body 3 and the second tube body are horizontally arranged so that the phase change material can be evenly distributed laterally, ensuring that heat is evenly absorbed and released in different parts of the pile, avoiding local overheating or overcooling, controlling thermal disturbance, and achieving dynamic heat balance. By setting a detection structure for temperature measurement, the thermal disturbance range is controlled to ensure that the frozen soil layer does not rise excessively due to hydration heat, ensuring that the interface is in a frozen state, and maintaining the bearing capacity of the pile foundation. This pile foundation can avoid structural damage caused by the collapse of the frozen soil layer due to temperature influence, and ensure structural safety. Specifically, by setting the first temperature control structure and the second temperature control structure in the steel cage 2 to transfer heat to the frozen soil layer, the first tube body 3 and the second tube body are filled with phase change material, which can absorb and release heat at a specific temperature. Through this characteristic, the heat input and thermal disturbance of the bored pile to the permafrost can be slowed down, thereby ensuring the long-term thermal stability of the pile foundation in the permafrost area. It can not only improve the thermal stability of pile foundations and reduce settlement and deformation caused by temperature changes, but also ensure the safety and stability of buildings. It has important practical application value for engineering construction in permafrost areas.

[0029] Furthermore, the volumes of n-hexadecane 6 filled in the plurality of first tubes 3 are equal, and the volumes of n-tetradecane 5 filled in the plurality of second tubes are equal. The equal volumes of phase change material in the first tubes 3 and the second tubes ensure uniform thermal stress distribution in each first tube 3 and the second tube during heat absorption and heat release, thereby achieving uniform heat regulation throughout.

[0030] Furthermore, multiple first tube bodies 3 and multiple second tube bodies are distributed in a rectangular array in the steel cage 2. The first tube body 3 and the second tube body can cover the transverse cross-section of the cast-in-place pile body 1 through the rectangular array arrangement, reducing heat transfer along the longitudinal direction of the pile body and reducing thermal disturbance to the permafrost.

[0031] like Figure 3As shown, further, seals 4 are provided at both ends of the plurality of first tubes 3 and the plurality of second tubes. The seals 4 are used to seal the phase change material within the first tubes 3 and the second tubes, and the seals 4 have the same structure. This embodiment provides a specific structure of the seal 4. Taking the first tube 3 as an example, the seal on the first tube 3 includes: a set screw 12, a washer 13, and a connecting ring 11. The set screw 12 is threadedly connected to the end of the first tube 3, thereby sealing the end of the first tube 3. The diameter of the rod portion of the set screw 12 matches the inner diameter of the first tube 3, thereby sealing the end of the first tube 3. In this embodiment, the inner diameter of the first tube 3 is approximately 20 cm to 30 cm. The washer 13 is disposed between the set screw 12 and the end of the first tube 3. The washer 13 abuts the set screw 12 and the end of the first tube 3, respectively, achieving a tighter connection and further enhancing the sealing effect. The connecting ring 11 is disposed on the set screw 12 to facilitate fixing the position of the first tube 3. The structure of the sealing member 4 connected to the first tube body 3 is also applicable to the connection with the second tube body.

[0032] Furthermore, both the first tube body 3 and the second tube body are steel pipes, and are made of stainless steel for enhanced protection. On the one hand, the steel pipe has a certain rigidity, which can support the overall structure, enhance structural strength, and share the lateral tensile stress caused by frost heave. On the other hand, the steel material has good thermal conductivity, which facilitates the phase change heat absorption and release of the phase change material, thereby improving heat transfer. In addition, the inner wall of the steel pipe in this embodiment is passivated to reduce electrochemical corrosion. The outer surface of the steel pipe is coated with an epoxy coal tar anti-corrosion layer to resist chloride ion corrosion in concrete. In this embodiment, both n-hexadecane 6 and n-tetradecane 5 are preferably high-stability phase change materials, and high-purity normal alkanes are selected. They have the characteristics of stable chemical properties, long phase change cycle life (phase change cycle number >10,000 times), no supercooling precipitation, and good compatibility with steel pipes.

[0033] Among them, Figure 4 The figure shows a schematic diagram comparing the heat transfer rate of the pile foundation of this embodiment with the heat transfer rate of the existing ordinary pile foundation. According to the figure, it can be concluded that the temperature fluctuation range of the pile foundation of this embodiment is: -5℃~18℃; the temperature fluctuation range of the existing ordinary pile foundation is: -5℃~30℃; it can be seen that the temperature control effect of the pile foundation of this embodiment is improved by 34%, which can reduce the risk of thermal stress cracks. The peak temperature of the pile foundation of this embodiment is 18℃, and the peak temperature of the existing ordinary pile foundation is 30℃, which is 40% lower than the existing one, which can significantly reduce the risk of thermal melting of frozen soil. The pile foundation of this embodiment uses a layered temperature control design of phase change materials to significantly reduce the temperature fluctuation of the pile body, reduce thermal disturbance to the frozen soil, and meet the engineering durability requirements in harsh environments.

[0034] Example 2 As a further improvement scheme based on Example 1, it further includes: a detection structure is set in the steel cage 2, and the temperature is measured by setting the detection structure to control the thermal disturbance range, ensure that the frozen soil layer does not rise excessively due to hydration heat, ensure that the interface is in a frozen state, and maintain the bearing capacity of the pile foundation. The detection structure includes: multiple temperature probes 7 and a controller 9. Multiple temperature probes 7 are evenly arranged in the steel cage 2, and multiple temperature probes 7 are used to detect the temperature of the cast-in-place pile body 1. In this embodiment, multiple temperature probes 7 are vertically set at the top, middle, and bottom of the steel cage 2, and the wires 8 connecting the temperature probes 7 are fixed to the steel cage 2 with insulating tape; the controller 9 is electrically connected to the multiple temperature probes 7, that is, the other end of the wire 8 is connected to the controller 9. The controller 9 is a concrete temperature recorder that can display the temperature detected by the temperature probe 7 in real time. By setting the detection structure to measure temperature and control the thermal disturbance range, it is ensured that the frozen soil layer does not rise excessively due to hydration heat, ensure that the interface is in a frozen state, and maintain the bearing capacity of the pile foundation. The controller 9 is used to receive the temperature signal detected by the temperature probe 7 and determine the working status of the first temperature control structure and the second temperature control structure based on the temperature signal. The temperature probe 7 is used to realize real-time temperature monitoring and feedback to the controller 9. The controller 9 can record the measured temperature and issue an early warning for subsequent concrete pouring and use to ensure the stability of the frozen soil. Specifically: (1) Verify whether the heat absorption and release of the phase change material effectively suppress the temperature rise, that is, verify whether the pile foundation is working effectively. (2) When pouring concrete, a large amount of hydration heat is generated. The temperature probe 7 can monitor whether the temperature change caused by this heat exceeds the frozen soil tolerance threshold to avoid short-term thermal disturbances during the construction period causing thawing and settling. (3) Continuously monitor the temperature of the pile body to ensure that the phase change material can still effectively maintain the frozen state of the frozen soil during many years of operation to prevent long-term creep damage. The above-mentioned detected temperature information can provide early warning information to construction personnel or operation and maintenance management personnel so that manual intervention measures can be taken in time. For example, during the construction phase, measures such as suspending pouring and adjusting the concrete mix ratio, such as adding retarders, lowering the mold entry temperature, temporarily covering the piles with insulation materials, and increasing ventilation and heat dissipation, can be taken to reduce the hydration heat peak and transfer rate. During the operation and maintenance phase, measures such as checking drainage around the piles to avoid hydrothermal erosion, assessing the surface cover, such as vegetation and insulation panels, can be taken to ensure they are intact. During extreme warm seasons, auxiliary heat dissipation measures, such as temporarily adding awnings, can be taken. Long-term strategies include analyzing the long-term performance of phase change materials based on continuous monitoring data to provide an optimized basis for the design of subsequent pile foundation projects in the same area, such as adjusting the type, dosage, and burial depth of phase change materials. Furthermore, in this embodiment, the controller 9 has a built-in phase change material performance attenuation algorithm model that uses long-term temperature monitoring data to determine whether the phase change interval has shortened or disappeared.

[0035] Among them, the other structures of this embodiment are consistent with those of Example 1, and are just optimizations made to Example 1.

[0036] Example 3 An embodiment of the present invention provides a method for constructing a pile foundation in a permafrost region, comprising the following steps: Step 1: Drill holes at the pile position according to the design requirements, which is the location where the steel cage 2 will be lowered; Step 2: Seal one end of the plurality of first tubes 3 and the plurality of second tubes using a sealing member 4; Step 3: n-hexadecane 6 is loaded into the plurality of first tube bodies 3 through the unsealed end, and n-tetradecane 5 is loaded into the plurality of second tube bodies through the unsealed end, and then the other ends of the plurality of first tube bodies 3 and the plurality of second tube bodies are sealed by the sealing member 4, so that the first tube bodies 3 and the second tube bodies are well sealed to prevent leakage of the phase change material; Step 4: Install the sealed multiple first tubes 3, multiple second tubes and multiple temperature probes 7 in the steel cage 2; Step 5: Lower the steel cage 2 into the drilled hole and pour concrete 10. The concrete 10 is self-compacting concrete, which can automatically fill the gaps between steel bars and pile holes, reduce defects such as honeycombs and holes, improve impermeability and freeze-thaw resistance, and have a lower hydration heat peak than ordinary concrete, reducing the risk of frozen soil thawing.

[0037] Furthermore, multiple first tube bodies 3 and multiple second tube bodies are tied to the steel cage 2 after passing steel wire through the semicircular connecting ring 11, so as to fix the position of the first tube body 3.

[0038] Furthermore, sealing the ends of the first tube body 3 and the second tube body includes the following steps: Step 1: Dry the connection between the first tube 3, the second tube and the set screw 12; Step 2: Fix the washer 13 and tighten the set screw 12; Step 3: Apply structural adhesive along the interfaces between the first tube 3 , the second tube and the set screw 12 .

[0039] The advantage of the present invention is that the pile foundation can avoid structural damage caused by the collapse of the permafrost layer due to temperature influence, thereby ensuring structural safety. Specifically, heat is transferred to the permafrost layer by arranging the first temperature control structure and the second temperature control structure in the steel cage. The first tube body and the second tube body are filled with phase change materials. The phase change materials can absorb and release heat at a specific temperature. Through this characteristic, the heat input and thermal disturbance of the bored pile to the permafrost can be slowed down, thereby ensuring the long-term thermal stability of the pile foundation in the permafrost area. It can not only improve the thermal stability of the pile foundation and reduce the settlement and deformation caused by temperature changes, but also ensure the safety and stability of the building, and has important practical application value for engineering construction in permafrost areas. Moreover, when the first tube body and the second tube body are used horizontally, the phase change material can be evenly distributed laterally, ensuring that heat is evenly absorbed and released in different parts of the pile, avoiding local overheating or overcooling, performing thermal disturbance control, and achieving dynamic thermal balance.

[0040] The above disclosures are only a few specific embodiments of the present invention. However, the embodiments of the present invention are not limited thereto. Any changes that can be conceived by those skilled in the art should fall within the scope of protection of the present invention.

Claims

1. A pile foundation in permafrost areas, characterized in that: include: A cast-in-place pile body (1) is provided with a steel cage (2) therein, wherein the steel cage (2) is coaxially arranged with the cast-in-place pile body (1); A first temperature control structure is arranged at one end of the steel cage (2), the first temperature control structure comprising a plurality of first tubes (3), both ends of the plurality of first tubes (3) being fixed to the steel cage (2), and the central axis of the first tubes (3) being perpendicular to the central axis of the steel cage (2), and the first tubes (3) being filled with n-hexadecane (6); A second temperature control structure is arranged at the other end of the steel cage (2), the second temperature control structure comprising a plurality of second tubes, both ends of the plurality of second tubes being fixed to the steel cage (2), and the central axis of the second tubes being perpendicular to the central axis of the steel cage (2), and the second tubes being filled with n-tetradecane (5).

2. The permafrost area pile foundation according to claim 1, characterized in that: The volumes of n-hexadecane (6) filled in the plurality of first tubes (3) are equal, and the volumes of n-tetradecane (5) filled in the plurality of second tubes are equal.

3. The permafrost area pile foundation according to claim 1, characterized in that: The plurality of first tube bodies (3) and the plurality of second tube bodies are distributed in the steel cage (2) in a rectangular array.

4. The permafrost area pile foundation according to claim 1, characterized in that: Both ends of the plurality of first tubes (3) and the plurality of second tubes are provided with sealing members (4), the sealing members comprising: A set screw (12) threadedly connected to the ends of the first tube (3) and the second tube; A washer (13) is arranged between the set screw (12) and the end of the first tube (3), and between the set screw (12) and the end of the second tube; A connecting ring (11) is arranged on the set screw (12).

5. The permafrost area pile foundation according to claim 1, characterized in that: The first tube body (3) and the second tube body are both steel tubes, and the outer walls of the steel tubes are coated with an epoxy coal tar anti-corrosion layer.

6. The permafrost area pile foundation according to claim 1, characterized in that: Also includes: A detection structure is arranged in the steel cage (2), and the detection structure comprises: A plurality of temperature measuring probes (7) are evenly arranged in the steel cage (2), and the plurality of temperature measuring probes (7) are used to detect the temperature of the cast-in-place pile body (1); A controller (9) is electrically connected to the plurality of temperature measuring probes (7), and the controller (9) is used to receive temperature signals detected by the temperature measuring probes (7), and to determine the working states of the first temperature control structure and the second temperature control structure based on the temperature signals.

7. A method for constructing a pile foundation in permafrost areas, using the pile foundation in permafrost areas according to any one of claims 1 to 6, characterized in that: The following steps are involved: Drill holes on the pile positions according to design requirements; Performing sealing treatment on one end of the plurality of first tubes (3) and the plurality of second tubes; n-hexadecane (6) is loaded into a plurality of the first tube bodies (3), n-tetradecane (5) is loaded into a plurality of the second tube bodies, and then the other ends of the plurality of the first tube bodies (3) and the plurality of the second tube bodies are sealed; Installing the sealed plurality of first tube bodies (3) and the sealed plurality of second tube bodies in the steel cage (2); The steel cage (2) is lowered into the drilled hole and then concrete (10) is poured.

8. The method for constructing a pile foundation in permafrost areas according to claim 7, wherein: A plurality of the first tube bodies (3) and a plurality of the second tube bodies are tied to the steel cage (2) after passing steel wire through the connecting ring (11).

9. The method for constructing a pile foundation in permafrost areas according to claim 7, wherein: The plurality of first tubes (3) filled with n-hexadecane (6) are installed in a rectangular array on the steel cage (2) at the junction of the seasonal frozen soil layer and the ground; the plurality of second tubes (5) filled with n-tetradecane (5) are installed in a rectangular array on the steel cage (2) at the junction of the seasonal frozen soil layer and the permafrost layer.

10. The method for constructing a pile foundation in permafrost areas according to claim 7, characterized in that: Sealing the ends of the first tube body (3) and the second tube body by means of the sealing member (4) comprises the following steps: Wipe dry the connection between the first tube body (3), the second tube body and the set screw (12); Fix the washer (13) and tighten the set screw (12); Structural adhesive is applied along the interfaces between the first tube body (3), the second tube body and the set screw (12).

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