Foundation pile structure and mounting method

Abstract

The invention relates to the technical field of building construction, in particular to a foundation pile structure and an installation method.The foundation pile structure comprises a pile foundation part and a protection part; the middle part of the pile foundation part is arranged in a frozen soil layer, the upper part of the pile foundation part is arranged above the frozen soil layer, and the lower part of the pile foundation part is arranged below the frozen soil layer; the axial length of the middle of the pile foundation part is larger than that of the lower portion of the pile foundation part, and the axial length of the upper portion of the pile foundation part is smaller than that of the lower portion of the pile foundation part. The protection part is coaxially arranged outside the pile foundation part, and a two-stage protection structure is arranged in the protection part and used for preventing the pile foundation part from corrosion and frost heaving. And the installation cost and the installation difficulty can be reduced by limiting the buried depth of the pile foundation part while the installation stability is guaranteed. And moreover, through the two-stage protection structure of the protection part, corrosion and frost heaving of the pile foundation part can be prevented, and the mounting stability is further improved.

Description

Technical Field

[0001] The invention belongs to the technical field of building construction, and in particular relates to a foundation pile structure and an installation method. Background Art

[0002] The penetration rate of photovoltaic power generation is gradually increasing, especially in high-altitude salt lake areas, where there are a large number of projects where photovoltaic power generation can be actually applied. Based on this, in order to ensure the smooth progress of photovoltaic power generation projects, it is necessary to conduct geological tests and adjust the foundation pile structure of photovoltaic power generation projects accordingly based on the test results.

[0003] The existing foundation pile structure is generally installed by inserting its lower part into the permafrost layer in the high-altitude salt lake area. However, due to the presence of a large number of salt compounds, which are highly corrosive, it is very easy to cause corrosion and damage to the foundation pile structure. In addition, due to the high water content, it is also very easy to freeze. Under the dual influence of corrosion and freeze, over time, the foundation pile structure will loosen and the installation stability of the foundation pile structure will no longer be maintained, thus making photovoltaic power generation ineffective. Although the purpose of improving installation stability can be achieved by deeply burying the foundation pile structure, it is very easy to cause a waste of the length of the foundation pile structure, thereby affecting the installation cost. At the same time, the installation difficulty of an overly long foundation pile structure will also increase accordingly.

[0004] Therefore, it is difficult for the existing foundation pile structure to reduce the cost and installation difficulty while ensuring installation stability. Summary of the invention

[0005] In view of the above problems, the present invention proposes a foundation pile structure and an installation method, wherein a foundation pile structure comprises:

[0006] A pile foundation part, wherein the middle part of the pile foundation part is arranged in the frozen soil layer, the upper part of the pile foundation part is arranged above the frozen soil layer, and the lower part of the pile foundation part is arranged below the frozen soil layer;

[0007] The axial length of the middle part of the pile foundation part is greater than the axial length of the lower part of the pile foundation part, and the axial length of the upper part of the pile foundation part is less than the axial length of the lower part of the foundation part;

[0008] The protection part is coaxially arranged outside the pile foundation part, and a two-level protection structure is arranged inside the protection part to prevent the pile foundation part from corrosion and frost heave.

[0009] In some specific embodiments, the protection portion includes:

[0010] A first protective layer, the first protective layer is disposed to cover the outer periphery of the pile foundation;

[0011] A second protective layer, the second protective layer is disposed on the outer periphery of the first protective layer;

[0012] The second protective layer can dry the pile foundation.

[0013] In some specific embodiments, the pile foundation part includes:

[0014] A first pile body, a second pile body and a third pile body which are coaxially arranged and connected in sequence;

[0015] The second pile body is arranged in the frozen soil layer, the first pile body is arranged above the frozen soil layer, and the third pile body is arranged below the frozen soil layer;

[0016] The axial length H2 of the second pile body is greater than the axial length H3 of the third pile body, and the axial length H1 of the first pile body is less than the axial length H3 of the third pile body.

[0017] In some specific embodiments, the first protective layer is disposed to cover the outer periphery of the second pile body, and two axial ends of the first protective layer are disposed to extend along the axial direction of the second pile body;

[0018] The second protective layer is disposed to cover the outer periphery of the first protective layer, and two axial ends of the second protective layer are extended along the axial direction of the first protective layer.

[0019] In some specific embodiments, the upper end of the first protective layer and the upper end of the second protective layer are respectively flush with the upper end of the second pile body;

[0020] The lower end of the first protective layer and the lower end of the second protective layer are respectively flush with the lower end of the second pile body.

[0021] In some specific embodiments, the first pile body, the second pile body and the third pile body are an integrated structure.

[0022] In some specific embodiments, the ratio of the axial length H2 of the second pile body to the axial length H3 of the third pile body is 4:3.

[0023] In some specific embodiments, the material of the first protective layer is resin-based fiber;

[0024] When the first protective layer is wetted, the first protective layer can solidify to isolate the soil in the external frozen soil layer.

[0025] In some specific embodiments, the material of the second protective layer is sandy soil material;

[0026] The second protective layer can drive moisture away from the second pile body, so as to dry the second protective layer.

[0027] A method for installing a foundation pile structure based on the same concept, using the foundation pile structure as described in any of the above specific embodiments, comprises the following steps:

[0028] Drilling to the bottom of the frozen soil layer to form a first hole for inserting the pile foundation, and then re-drilling along the axial direction of the first hole to the bottom of the frozen soil layer to form a second hole for accommodating the pile foundation, wherein the diameter of the second hole is larger than the first hole;

[0029] Arrange a part of the protective structure of the protective part around the outer periphery of the pile foundation part;

[0030] Inserting the pile foundation part, driving the lower part of the pile foundation part to be inserted into the first hole until it abuts against the bottom wall of the first hole;

[0031] Another part of the protection structure of the protection part is filled in the second hole to form a two-level protection structure of the protection part.

[0032] The foundation pile structure of the present invention is provided with a pile foundation part penetrating the frozen soil layer, so that the axial length of the lower part of the pile foundation part inserted below the frozen soil layer is greater than the axial length of the upper part of the pile foundation part located above the frozen soil layer, thereby improving the installation stability. At the same time, the axial length of the lower part of the pile foundation part inserted below the frozen soil layer is less than the axial length of the middle part of the pile foundation part penetrating the frozen soil layer, thereby limiting the depth of the pile foundation part into the ground. While ensuring the installation stability, by limiting the depth of the pile foundation part into the ground, the installation cost and installation difficulty can be reduced. In addition, by means of a two-stage protective structure of the protective part arranged outside the pile foundation part, the pile foundation part can be prevented from corrosion and frost heave, further improving the installation stability.

[0033] The installation method of the foundation pile structure of the present invention has the same beneficial effects as the foundation pile structure described above because it adopts the foundation pile structure described above, so it will not be described in detail here.

[0034] Other features and advantages of the present invention will be described in the following description, and partly become obvious from the description, or be understood by implementing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures pointed out in the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] 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 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.

[0036] Figure 1 A schematic diagram of a foundation pile structure in an embodiment of the present invention is shown;

[0037] Figure 2 A top view of the middle portion of a foundation pile structure in an embodiment of the present invention is shown;

[0038] Figure 3 A flow chart showing a method for installing a foundation pile structure in an embodiment of the present invention is shown.

[0039] In the figure, 100, pile foundation; 110, first pile body; 120, second pile body; 130, third pile body; 200, protection part; 210, first protection layer; 220, second protection layer. DETAILED DESCRIPTION

[0040] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0041] Reference Figure 1 The present invention provides a foundation pile structure, including: a pile foundation part 100 and a protective part 200. The middle part of the pile foundation part 100 is arranged in the frozen soil layer, the upper part of the pile foundation part 100 is arranged above the frozen soil layer, and the lower part of the pile foundation part 100 is arranged below the frozen soil layer. The axial length of the middle part of the pile foundation part 100 is greater than the axial length of the lower part of the pile foundation part 100, and the axial length of the upper part of the pile foundation part 100 is less than the axial length of the lower part of the foundation part. The protective part 200 is coaxially arranged outside the pile foundation part 100, and a two-level protective structure is arranged in the protective part 200 to prevent the pile foundation part 100 from corrosion and frost heave.

[0042] Specifically, the pile foundation part 100 is vertically penetrated into the frozen soil layer so that the lower part of the pile foundation part 100 can be inserted below the frozen soil layer. At the same time, the middle part of the pile foundation part 100 is located in the frozen soil layer, and the upper part of the frozen soil layer is located above the frozen soil layer. By inserting the pile foundation part 100 below the frozen soil layer, the depth of the pile foundation part 100 into the soil can be increased while completing the installation process, and the installation stability of the pile foundation part 100 can be improved. Among them, the axial length of the lower part of the pile foundation part 100 inserted below the frozen soil layer is greater than the axial length of the upper part of the pile foundation part 100 located above the frozen soil layer, thereby further improving the installation stability of the pile foundation part 100, and the axial length of the lower part of the pile foundation part 100 inserted below the frozen soil layer is less than the axial length of the middle part of the pile foundation part 100 penetrated into the frozen soil layer, thereby limiting the burial depth of the pile foundation part 100, and while providing sufficient frost pullout force and ensuring the installation stability of the pile foundation part 100, by limiting the burial depth of the pile foundation part 100, the installation cost and installation difficulty of the pile foundation part 100 are reduced, and by limiting the burial depth of the pile foundation part 100, the setting length of the pile foundation part 100 itself can be further controlled, thereby reducing the manufacturing cost of the pile foundation part 100. In addition, the protection part 200 is coaxially arranged on the outside of the pile foundation part 100 along the axial direction of the pile foundation part 100, so that the pile foundation part 100 can be isolated from the outside through the protection part 200, thereby avoiding corrosion and frost heave of the pile foundation part 100. Among them, a two-level protection structure is arranged in the protection part 200. The first-level protection structure of the protection part 200 can prevent the corrosive medium containing salt compounds in the soil from penetrating, avoid the pile foundation part 100 from corrosion, and avoid mechanical damage, thereby ensuring the service life of the pile foundation part 100 and improving the installation stability of the pile foundation part 100. The second-level protection structure of the protection part 200 can reduce the water content and moisture content of the surrounding soil, keep the surrounding soil in a dry state, thereby reducing the frost heave effect of the surrounding soil on the pile foundation part 100, ensuring the service life of the pile foundation part 100 and improving the installation stability of the pile foundation part 100.

[0043] In some specific embodiments of the present invention, referring to Figure 1The protection part 200 includes: a first protection layer 210 and a second protection layer 220. The first protection layer 210 is disposed to cover the outer periphery of the pile foundation part 100. The second protection layer 220 is disposed to cover the outer periphery of the first protection layer 210. The second protection layer 220 can dry the pile foundation part 100. Specifically, the first protective layer 210 is disposed around the periphery of the pile foundation part 100 and abuts against the outer wall of the pile foundation part 100, so that the first protective layer 210 forms a first-level protective structure of the protective part 200. The first protective layer 210 can prevent the corrosive medium containing salt compounds in the soil from penetrating, thereby preventing the pile foundation part 100 from being corroded and mechanically damaged. The second protective layer 220 is disposed around the periphery of the first protective layer 210 and abuts against the side of the first protective layer 210 away from the pile foundation part 100, so that the second protective layer 220 forms a second-level protective structure of the protective part 200. The second protective layer 220 can reduce the water content and moisture content of the surrounding soil, so that the surrounding soil is in a dry state, thereby drying the pile foundation part 100, further preventing the pile foundation part 100 from being corroded, and the surrounding soil that remains in a dry state can weaken the frost heave effect of the surrounding soil on the pile foundation part 100. The service life of the pile foundation part 100 is ensured, and the installation stability of the pile foundation part 100 is improved.

[0044] In some specific embodiments of the present invention, referring to Figure 1 The pile foundation part 100 includes: a first pile body 110, a second pile body 120 and a third pile body 130 which are coaxially arranged and connected in sequence. The second pile body 120 is arranged in the frozen soil layer, the first pile body 110 is arranged above the frozen soil layer, and the third pile body 130 is arranged below the frozen soil layer. The axial length H2 of the second pile body 120 is greater than the axial length H3 of the third pile body 130, and the axial length H1 of the first pile body 110 is less than the axial length H3 of the third pile body 130. Specifically, the lower end of the first pile body 110 is connected to the upper end of the second pile body 120, and the lower end of the second pile body 120 is connected to the upper end of the third pile body 130. The first pile body 110, the second pile body 120 and the third pile body 130 are coaxially arranged to form the pile foundation part 100, wherein the first pile body 110 forms the upper part of the pile foundation part 100, the second pile body 120 forms the middle part of the pile foundation part 100, and the third pile body 130 forms the lower part of the pile foundation part 100, so that while ensuring the installation stability, it is convenient to control the axial length of the upper part, the middle part and the lower part of the pile foundation part 100 respectively through the first pile body 110, the second pile body 120 and the third pile body 130, thereby facilitating the restriction of the overall axial length of the pile foundation part 100, while ensuring the installation stability, reducing the installation cost and installation difficulty.

[0045] In some specific embodiments of the present invention, referring to Figure 1, the first pile body 110, the second pile body 120 and the third pile body 130 are an integrated structure. That is, when manufacturing the first pile body 110, the second pile body 120 and the third pile body 130, the first pile body 110, the second pile body 120 and the third pile body 130 can be processed separately, so as to facilitate the control of the axial lengths of the upper part, the middle part and the lower part of the pile foundation part 100. After processing, the first pile body 110, the second pile body 120 and the third pile body 130 are connected in sequence by welding or other processes, so that the first pile body 110, the second pile body 120 and the third pile body 130 form an inseparable integrated structure, which is convenient for installation and improves the installation stability after installation.

[0046] In some specific embodiments of the present invention, referring to Figure 1 The first protective layer 210 is disposed on the outer periphery of the second pile body 120, and the two axial ends of the first protective layer 210 are extended along the axial direction of the second pile body 120. The second protective layer 220 is disposed on the outer periphery of the first protective layer 210, and the two axial ends of the second protective layer 220 are extended along the axial direction of the first protective layer 210. Specifically, the first protective layer 210 is coaxially coated on the outer wall of the second pile body 120, and the two axial ends of the first protective layer 210 are extended up and down along the axial direction of the second pile body 120, so that the second pile body 120 can be completely coated in the first protective layer 210. The second protective layer 220 is coaxially coated on the side of the first protective layer 210 away from the second pile body 120, that is, the outer side, and the two ends of the second protective layer 220 in the axial direction are also extended up and down along the axial direction of the second pile body 120, so that the first protective layer 210 coated with the second pile body 120 can be completely coated in the second protective layer 220, so that the second pile body 120 can be indirectly completely coated in the second protective layer 220. Because the second pile body 120 is penetrated in the frozen soil layer, the second pile body 120 is most disturbed by the frozen soil layer. The first protective layer 210 and the second protective layer 220 can completely isolate the second pile body 120 from the soil of the frozen soil layer, thereby preventing the second pile body 120 from being affected by corrosion and frost heave, ensuring the service life of the pile foundation part 100 including the second pile body 120, and improving the installation stability of the pile foundation part 100 including the second pile body 120. Durable duration.

[0047] In some specific embodiments of the present invention, referring to Figure 1, the upper end of the first protective layer 210 and the upper end of the second protective layer 220 are respectively flush with the upper end of the second pile body 120. The lower end of the first protective layer 210 and the lower end of the second protective layer 220 are respectively flush with the lower end of the second pile body 120. Specifically, because the second pile body 120 is only arranged in the frozen soil layer, the upper end of the first protective layer 210 and the upper end of the second protective layer 220 are both extended to the top of the frozen soil layer along the axial direction of the second pile body 120, and the lower end of the first protective layer 210 and the lower end of the second protective layer 220 are both extended to the bottom of the frozen soil layer along the axial direction of the second pile body 120, so that the second pile body 120 can be directly or indirectly covered to avoid being affected by the frozen soil layer. At the same time, it can also avoid the upper end or lower end of the first protective layer 210 and the second protective layer 220 from extending to the first pile body 110 or the third pile body 130, avoiding waste due to the excessive length of the first protective layer 210 and the second protective layer 220.

[0048] It should be noted that the pile foundation 100 is most obviously affected by the corrosion and frost heave of the soil in the frozen soil layer. If the upper end or the lower end of the first protective layer 210 and the second protective layer 220 is extended to the first pile body 110 or the third pile body 130, the increase in material cost and installation difficulty will not be worth the gain.

[0049] In some specific embodiments of the present invention, referring to Figure 1 , the ratio between the axial length H2 of the second pile body 120 and the axial length H3 of the third pile body 130 is 4:3. Specifically, for example, when the thickness of the frozen soil layer, i.e., the axial length H2 of the second pile body 120, is 2.0 m, the axial length H3 of the third pile body 130 can be 1.5 m. While ensuring the installation stability, the overall length of the pile foundation part 100 can be greatly reduced, thereby greatly reducing the investment in the installation construction project, reducing the installation cost and installation difficulty.

[0050] In some specific embodiments of the present invention, the material of the first protective layer 210 is resin-based fiber. When the first protective layer 210 is wetted, the first protective layer 210 can be cured to isolate the soil in the external frozen soil layer. Specifically, the first protective layer 210 can be a flexible resin-based fiber reinforced protective belt. The flexible resin-based fiber reinforced protective belt is a finished product, and it has its own adhesiveness, which is convenient for installation. During the installation process, the first protective layer 210 can be flexibly coated on the outer wall of the second pile body 120 of the pile foundation part 100, and then the pile foundation part 100 coated with the first protective layer 210 is lowered into the ground until the second pile body 120 of the pile foundation part 100 and the first protective layer 210 are completely in the frozen soil layer. The first protective layer 210 is not affected by outdoor weather conditions, and its own adhesiveness facilitates the coating and attachment setting, and it will immediately react and solidify into a dense structure after being wetted by water spray, so that the second pile body 120 is isolated from the soil in the external frozen soil layer, thereby avoiding the influence of the floating of the groundwater level. The installation and construction is convenient, the plasticity is good, the cost is low and it is environmentally friendly. It can effectively prevent the infiltration of corrosive media containing salt compounds and mechanical damage for a long time, and protect the second pile body 120 of the pile foundation part 100 from being corroded by corrosive ions.

[0051] Furthermore, the radial thickness of the first protective layer 210 is 2.0 mm, so that the dense structure formed by curing in water can meet the following requirements:

[0052] Scratch resistance ≤500um, wear resistance ≤7mg / 100mr, longitudinal tensile strength ≥284Mpa.

[0053] In some specific embodiments of the present invention, the material of the second protective layer 220 is sandy soil material. The second protective layer 220 can drive moisture away from the second pile body 120, and is used to dry the second protective layer. Specifically, the second protective layer 220 can be medium-coarse sand, which has poor water retention and strong water permeability, and can greatly reduce the water content and moisture content of the surrounding soil, so that the surrounding soil of the pile foundation part 100 can be kept relatively dry even in severe winter, thereby reducing the frost heave effect of the surrounding soil.

[0054] Through frost heave test simulation, under the same environmental conditions, by replacing silty soil with medium-coarse sand, the strong frost heave level can be reduced to a weak frost heave level, thereby significantly reducing the frost pullout force generated by soil frost heave on the pile foundation 100, ensuring the effectiveness of limiting the length of the pile foundation 100, and further providing a basis for reducing the cost of the pile foundation 100. At the same time, the soil of medium-coarse sand is relatively loose and can undergo corresponding natural deformation after being squeezed by the frost heave of the surrounding soil, thereby reducing the frost heave force while preventing the first protective layer 210 from being adversely affected by external forces.

[0055] Reference Figure 3The present invention also provides a method for installing a foundation pile structure, which adopts a foundation pile structure as described in any of the above-mentioned specific embodiments, and includes the following steps: drilling to the bottom of the frozen soil layer to form a first hole for inserting the pile foundation part 100, and then re-drilling to the bottom of the frozen soil layer along the axial direction of the first hole to form a second hole for accommodating the pile foundation part 100, wherein the diameter of the second hole is larger than the first hole. A part of the protective structure of the protective part 200 is arranged around the outer periphery of the pile foundation part 100. The pile foundation part 100 is lowered, and the lower part of the pile foundation part 100 is driven to be inserted into the first hole until it abuts against the bottom wall of the first hole. Another part of the protective structure of the protective part 200 is filled in the second hole to form a two-level protective structure of the protective part 200.

[0056] Specifically, a first hole for inserting the pile foundation 100 is formed by drilling a hole to the bottom of the frozen soil layer through a drilling tool, and then a second hole is drilled along the axial direction of the first hole to the bottom of the frozen soil layer to form a second hole for accommodating the pile foundation 100, wherein the diameter of the second hole is larger than the first hole, so that the first pile body 110 of the pile foundation 100 is inserted through the first hole, and the second pile body 120 of the pile foundation 100 is accommodated through the second hole. Figure 2 , the first protective layer 210 of the protective part 200 is coaxially wound on the outer periphery of the second pile body 120, so that the second protective layer 220 can completely cover the outer wall of the second pile body 120. The pile foundation part 100 is lowered, and the lower end of the first pile body 110 is driven to be inserted into the first hole until the end surface of the bottom end of the first pile body 110 abuts against the bottom wall of the first hole. At this time, the end surface of the upper end of the first pile body 110 and the end surface of the lower end of the second pile body 120 are flush with the bottom wall of the second hole, and the first protective layer 210 is located in the second hole and there is a gap between the first protective layer 210 and the inner wall of the second hole. Medium-coarse sand is filled into the gap between the first protective layer 210 and the inner wall of the second hole until it is filled, thereby forming a second protective layer 220 that completely covers the outer side of the first protective layer 210, and a two-level protective structure of the protective part 200 is formed by the first protective layer 210 and the second protective layer 220.

[0057] The difference between the depth of the first hole and the depth of the second hole is the axial length H1 of the first pile body 110, and the depth of the second hole is the axial length H2 of the second pile body 120. In addition, the diameter of the first hole is the diameter of the pile foundation 100, and the diameter of the first hole is 150 mm or more. The diameter of the second hole is 300 mm or more, so that the difference between the diameter of the first hole and the diameter of the second hole is greater than 150 mm, and the difference of 150 mm is the reserved space for setting the first protective layer 210 and the second protective layer 220.

[0058] Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent substitutions for some of the technical features therein; and these modifications or substitutions do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A foundation pile structure, characterized in that: include: A pile foundation part (100), wherein the middle part of the pile foundation part (100) is arranged in a frozen soil layer, the upper part of the pile foundation part (100) is arranged above the frozen soil layer, and the lower part of the pile foundation part (100) is arranged below the frozen soil layer; The axial length of the middle part of the pile foundation part (100) is greater than the axial length of the lower part of the pile foundation part (100), and the axial length of the upper part of the pile foundation part (100) is less than the axial length of the lower part of the foundation part; A protection part (200) is coaxially arranged outside the pile foundation part (100), and a two-level protection structure is arranged inside the protection part (200) to prevent the pile foundation part (100) from corrosion and frost heave.

2. The foundation pile structure according to claim 1, characterized in that: The protection part (200) comprises: A first protective layer (210), the first protective layer (210) being disposed to cover the outer periphery of the pile foundation part (100); A second protective layer (220), the second protective layer (220) being disposed to cover the outer periphery of the first protective layer (210); The second protective layer (220) can dry the pile foundation part (100).

3. The foundation pile structure according to claim 2, characterized in that: The pile foundation part (100) comprises: A first pile body (110), a second pile body (120) and a third pile body (130) which are coaxially arranged and connected in sequence; The second pile body (120) is arranged in a frozen soil layer, the first pile body (110) is arranged above the frozen soil layer, and the third pile body (130) is arranged below the frozen soil layer; The axial length H2 of the second pile body (120) is greater than the axial length H3 of the third pile body (130), and the axial length H1 of the first pile body (110) is less than the axial length H3 of the third pile body (130).

4. The foundation pile structure according to claim 3, characterized in that: The first protective layer (210) is disposed to cover the outer periphery of the second pile body (120), and two axial ends of the first protective layer (210) are extended along the axial direction of the second pile body (120); The second protective layer (220) is disposed to cover the outer periphery of the first protective layer (210), and two axial ends of the second protective layer (220) are extended along the axial direction of the first protective layer (210).

5. The foundation pile structure according to claim 4, characterized in that: The upper end of the first protective layer (210) and the upper end of the second protective layer (220) are respectively flush with the upper end of the second pile body (120); The lower end of the first protective layer (210) and the lower end of the second protective layer (220) are respectively flush with the lower end of the second pile body (120).

6. The foundation pile structure according to any one of claims 3 to 5, characterized in that: The first pile body (110), the second pile body (120) and the third pile body (130) are an integrated structure.

7. The foundation pile structure according to any one of claims 3 to 5, characterized in that: The ratio between the axial length H2 of the second pile body (120) and the axial length H3 of the third pile body (130) is 4:

3.

8. The foundation pile structure according to any one of claims 3 to 5, characterized in that: The material of the first protective layer (210) is resin-based fiber; When the first protective layer (210) is wetted, the first protective layer (210) can solidify to isolate the soil in the external frozen soil layer.

9. The foundation pile structure according to any one of claims 3 to 5, characterized in that: The material of the second protective layer (220) is sandy soil; The second protective layer (220) can drive moisture away from the second pile body (120), so as to dry the second protective layer (220).

10. A method for installing a foundation pile structure, using the foundation pile structure according to any one of claims 1 to 9, characterized in that: The following steps are involved: Drilling to the bottom of the frozen soil layer to form a first hole for inserting a pile foundation part (100), and then re-drilling along the axial direction of the first hole to the bottom of the frozen soil layer to form a second hole for accommodating the inserted pile foundation part (100), wherein the diameter of the second hole is larger than that of the first hole; A partial protection structure of the protection part (200) is arranged around the outer periphery of the pile foundation part (100); Inserting the pile foundation part (100) and driving the lower part of the pile foundation part (100) to be inserted into the first hole until it contacts the bottom wall of the first hole; Another part of the protection structure of the protection part (200) is filled in the second hole to form a two-level protection structure of the protection part (200).

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