A wind power tower pile foundation and construction method for self-weight collapsible loess site

Abstract

The present invention belongs to the technical field of foundation, and more particularly, relates to a wind turbine tower pile foundation and construction method for a self-weight collapsible loess site. The present invention is composed of foundation piles arranged under a foundation pit with a stepped slope, a foundation pedestal for a generator tower arranged on the upper surface of the bottom of the foundation pit, a first layer of backfill soil, hidden scattered water, a second layer of backfill soil, and a surface covering soil layer arranged sequentially from bottom to top around the foundation pedestal for the wind turbine tower. The present invention performs multiple waterproofing protections on the foundation in a large range, reduces the possibility of foundation flooding, reduces resource consumption, and reduces the investment in the foundation of the wind turbine tower. The present invention eliminates the factors of collapsibility through multiple waterproofing, and is safe and economical. The present invention restores the surface and protects the environment. The present invention uses local materials, fully utilizes materials, and saves resources.

Description

Technical Field

[0001] The invention belongs to the technical field of foundation, and in particular relates to a wind power tower pile foundation and a construction method for a deadweight collapsible loess site. Background Art

[0002] When collapsible loess is soaked in water under a certain pressure, the soil structure is quickly destroyed and significant and uneven additional subsidence occurs. Loess that collapses when soaked in water under the pressure of its own weight is called self-weight collapsible loess. The tower of a wind turbine built in such a collapsible loess area should implement the principles of safety, applicability, economic rationality, environmental protection, and resource conservation, carry out foundation treatment, adopt appropriate foundation forms and waterproofing measures, and take into account ecological and environmental protection. This is a difficult problem to solve.

[0003] The foundation of wind turbine towers generally adopts reinforced concrete extended foundation or pile foundation according to the geological conditions. Initial construction experience has been gained by building wind farms in loess sites with self-weight collapsible soil. However, the foundation treatment and foundation structure of wind turbine towers are not yet mature. In loess sites with self-weight collapsible soil, especially when the self-weight collapsible soil layer is thick, pile foundations are generally used to penetrate the collapsible loess layer. The foundation piles not only have to bear the load of the upper wind turbine tower, but also have to consider the downward tension caused by the negative friction resistance of the loess that may collapse due to self-weight. The piles are long, the construction materials are consumed, the economic effect is poor, and the resources are not fully utilized. At the same time, in order to prevent the adverse effects of the self-weight collapse of the loess foundation caused by the infiltration of surface rainwater on the foundation piles, a certain range of the surface around the wind turbine tower is set with concrete or geotextiles and other materials. This makes it impossible for plants to grow in a considerable range around the wind foundation, affecting ecological protection. Summary of the invention

[0004] The present invention provides a wind turbine tower pile foundation and a construction method for a self-weight collapsible loess site. One purpose is to provide a wind turbine tower pile foundation that can take multiple effective waterproof measures over a large range to reduce the possibility of foundation flooding, improve the bearing capacity of the piles, reduce resource consumption, and reduce the investment in the foundation of the wind turbine tower; the second purpose is to provide a wind turbine tower pile foundation that can be waterproof under the ground, restore the surface after the foundation construction is completed, and reduce the impact of the wind turbine tower construction on the fragile local ecological environment.

[0005] To achieve the above object, the technical solution adopted by the present invention is:

[0006] A wind turbine tower pile foundation in a self-weight collapsible loess site comprises at least a foundation pit, and also includes a wind turbine tower foundation pedestal, a second layer of backfill soil, hidden drainage, a first layer of backfill soil and foundation piles; the pit slope of the foundation pit is stepped; the foundation piles are arranged at the lower part of the pit bottom, and the tops of the foundation piles are flush with the pit bottom surface; the wind turbine tower foundation is connected to the pit bottom; the first layer of backfill soil, hidden drainage and the second layer of backfill soil are arranged in sequence from bottom to top around the wind turbine tower foundation pedestal; the upper surface of the bottom pedestal of the wind turbine tower foundation pedestal has an outward and downward slope.

[0007] The wind turbine tower foundation pedestal is a reinforced concrete integrated structure composed of a short cylinder, a frustum and a small cylinder from bottom to top; the upper surface of the hidden water spill is flush with the bottom edge of the frustum, and a gap is provided between the hidden water spill and the wind turbine tower foundation pedestal.

[0008] The bottom of the foundation pit is circular and the slope ratio of the foundation pit side slope is 1:0.5.

[0009] The first layer of backfill soil is lime soil or cement soil, and the compaction coefficient is not less than 0.95; the second layer of backfill soil has a compaction coefficient of not less than 0.95 and a dry density of not less than 18kN / m 3 of plain soil.

[0010] The foundation pit slope of the foundation pit adopts two steps, a platform is arranged between the two steps of the foundation pit slope, and the hidden water dispersion is arranged on the platform.

[0011] The hidden flashing is cast with C10 plain concrete, with a thickness of 90-200 mm and a width of 2-4 m. Expansion joints are arranged at intervals along the circumference of the hidden flashing, and the upper surface of the hidden flashing has a slope of 4-7% outward and downward.

[0012] The upper surfaces of the first layer of backfill soil and the second layer of backfill soil both have a slope of 4-7% toward the outside of the foundation.

[0013] The edge of the foundation pit bottom is 0.6 to 1 m away from the bottom edge of the wind turbine tower foundation pedestal.

[0014] It also includes a surface soil layer; the surface soil layer is arranged on the second layer of backfill soil, the thickness of the surface soil layer is 0.8m to 1.0m; the upper surface of the surface soil layer is arranged with a slope downward.

[0015] A construction method for a wind power tower pile foundation on a self-weight collapsible loess site comprises the following steps

[0016] Step 1: Pile construction

[0017] Carry out foundation pile construction and make the top of the foundation pile located at a preset position below the ground;

[0018] Step 2: Excavation of foundation pit

[0019] Excavate a circular foundation pit with a two-step slope. The slope ratio of the two steps is 1:0.5. A foundation pit slope platform is set between the two steps. Preserve the surface soil layer.

[0020] Step 3: Construction of wind turbine tower foundation pedestal

[0021] After the completion of step 2, the foundation pedestal of the wind turbine tower is constructed on the bottom of the foundation pit, and the lower outer edge of the foundation pedestal of the wind turbine tower is 0.6 to 1 m away from the edge of the bottom of the foundation pit;

[0022] Step 4: First backfill

[0023] After step 3 is completed, the first layer of backfill soil with a compaction coefficient of not less than 0.95 is used to perform the first compaction backfill around the foundation pedestal of the wind turbine tower. The first layer of backfill soil is backfilled to the height of the foundation pit slope platform; the upper surface of the first layer of backfill soil has a slope toward the outside of the foundation;

[0024] Step 5: Construction of hidden water

[0025] After step 4 is completed, dark scattered water is poured on the upper surface of the first layer of backfill soil and the foundation pit slope platform; the upper surface of the dark scattered water is flush with the bottom edge of the cone of the wind turbine tower foundation pedestal and the upper surface of the dark scattered water has an outward downward slope; a gap is set between the dark scattered water and the wind turbine tower foundation pedestal, and expansion joints are set at intervals along the dark scattered water; the gap and expansion joint are filled with caulking agent;

[0026] Step 6: Second backfill

[0027] After step 5 is completed, the second layer of backfill soil is compacted layer by layer from the top of the hidden water to the position 0.8m to 1.0m from the top of the foundation pit. The top surface of the second layer of backfill soil has a slope toward the outside of the foundation;

[0028] Step 7: Backfilling of topsoil

[0029] After step six is ​​completed, the surface soil preserved during the excavation of the foundation pit in step two is used to backfill above the compacted second layer of backfill soil to restore the natural surface and revegetate.

[0030] Beneficial effects:

[0031] 1. The present invention uses compacted soil below the surface soil as the first waterproof and drainage measure, uses the outward and downward slope of the cone in the foundation pedestal of the wind turbine tower in combination with hidden water dispersion as the second waterproof and drainage measure, and backfills the surrounding area of ​​the foundation pedestal of the wind turbine tower with ash soil or cement soil as the third waterproof measure, and waterproofs the pile foundation in a larger range, thereby reducing the possibility of waterlogging of the foundation, improving the bearing capacity of the pile foundation, reducing resource consumption, and reducing the investment in the foundation of the wind turbine tower.

[0032] 2. The present invention restores the ground surface and protects the environment. The present invention adopts a waterproofing method combining a cone in the foundation of the wind turbine tower and hidden water dispersion, which changes the existing method of waterproofing the ground surface. After the foundation construction is completed, the surface soil is restored with the preserved surface soil to adapt to plant growth and reduce the impact of wind turbine tower construction on the fragile ecological environment.

[0033] 3. The present invention uses local materials to save resources. The present invention uses the existing foundation as the rammed soil with a certain waterproof property for counterweight setting, and uses the excavated soil from the foundation pit as the source of the plain soil, lime soil or cement soil rammed soil waterproof material, and also uses the surface soil preserved during excavation as the material for restoring the surface, so as to facilitate vegetation reconstruction.

[0034] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention and implement it according to the contents of the specification, the following is a detailed description of the preferred embodiments of the present invention in conjunction with the accompanying 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 drawings required for use in the embodiments 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.

[0036] Figure 1 It is a schematic diagram of the structure of the present invention.

[0037] In the figure: 1-wind turbine tower pile foundation pedestal; 2-surface soil layer; 3-second backfill soil layer; 4-slope of foundation pit; 5-hidden water; 6-asphalt mortar caulking; 7-first backfill soil layer; 8-bottom of foundation pit; 9-foundation piles; 10-natural surface. DETAILED DESCRIPTION

[0038] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only 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.

[0039] Embodiment 1:

[0040] according to Figure 1 A wind turbine tower pile foundation in a self-weight collapsible loess site shown in the figure comprises at least a foundation pit, and also includes a wind turbine tower foundation pedestal 1, a second layer of backfill soil 3, hidden drainage 5, a first layer of backfill soil 7 and foundation piles 9; the foundation pit slope 4 of the foundation pit is stepped; the foundation piles 9 are arranged at the lower part of the foundation pit bottom 8 of the foundation pit, and the tops of the foundation piles 9 are flush with the surface of the foundation pit bottom 8; the wind turbine tower foundation pedestal 1 is connected to the foundation pit bottom 8; the first layer of backfill soil 7, hidden drainage 5 and the second layer of backfill soil 3 are arranged in sequence from bottom to top around the wind turbine tower foundation pedestal 1; the upper surface of the bottom pedestal of the wind turbine tower foundation pedestal 1 has an outward and downward slope.

[0041] In actual use, firstly, the foundation piles 9 are constructed, and the tops of the foundation piles 9 are located at a preset position below the ground; then, a circular foundation pit is excavated with a foundation pit bottom 8, and the foundation pit slope 4 is stepped, the slope ratio of the foundation pit slope 4 is 1:0.5, and a foundation pit slope platform is provided between the stepped foundation pit slopes 4; then, the wind turbine tower foundation pedestal 1 is constructed on the foundation pit bottom 8, and the lower outer edge of the wind turbine tower foundation pedestal 1 is 0.6 to 1 m away from the edge of the foundation pit bottom 8; after the wind turbine tower foundation pedestal 1 is built, a first layer of backfill soil 7 of ash soil or cement soil with a compaction coefficient of not less than 0.95 is used around the wind turbine tower foundation pedestal 1 for the first time for compaction and backfilling, and the first layer of backfill soil 7 is compacted and backfilled. Backfill to the height of the foundation pit slope platform; the upper surface of the first backfill soil 7 has a slope toward the outside of the foundation; then, cast and construct hidden spillway 5 on the upper surface of the first layer of backfill soil 7 and the foundation pit slope platform; the upper surface of the hidden spillway 5 is flush with the bottom edge of the cone of the wind turbine tower foundation pedestal 1 and the upper surface of the hidden spillway 5 has an outward and downward slope; a gap is provided between the hidden spillway 5 and the wind turbine tower foundation pedestal 1, and expansion joints are provided at intervals along the hidden spillway 5; the gaps and expansion joints are filled with caulking agent; after the hidden spillway 5 is built, the second layer of backfill soil 3 is used to compact in layers from the top of the hidden spillway 5 to the position 0.8m to 1.0m from the top of the foundation pit, and the top surface of the second layer of backfill soil 3 has a slope toward the outside of the foundation.

[0042] The present invention uses the compacted soil below the surface soil as the first waterproof and drainage measure, uses the outward and downward slope of the cone in the foundation pedestal of the wind turbine tower frame in combination with hidden water dispersion as the second waterproof and drainage measure, uses the first layer of backfill soil 7 backfilled around the foundation pedestal of the wind turbine tower frame as the third waterproof measure, and performs waterproof protection on the pile foundation in a larger range, thereby reducing the possibility of foundation flooding, improving the bearing capacity of the foundation piles, reducing resource consumption, and reducing the investment in the foundation of the wind turbine tower frame.

[0043] Embodiment 2:

[0044] according to Figure 1 The wind turbine tower pile foundation shown in the embodiment of the present invention is different from the embodiment 1 in that the wind turbine tower foundation pedestal 1 is an integrated reinforced concrete structure composed of a short cylinder, a frustum and a small cylinder from bottom to top; the upper surface of the hidden water spill 5 is flush with the bottom edge of the frustum, and a gap is provided between the hidden water spill 5 and the wind turbine tower foundation pedestal 1.

[0045] In actual use, the wind turbine tower foundation pedestal 1 adopts this technical solution, which can effectively drain the top surface of the wind turbine tower foundation pedestal 1. The frustum edge of the wind turbine tower foundation pedestal 1 is flush with the upper surface of the dark water 5, so that the water of the wind turbine tower foundation pedestal 1 is drained to the far end of the wind turbine tower foundation pedestal 1, effectively reducing the possibility of foundation flooding.

[0046] In specific applications, the gap between the hidden diffuser 5 and the foundation pedestal 1 of the wind turbine tower is 10 mm wide and is caulked with asphalt mastic.

[0047] In specific applications, the cone of the wind turbine tower foundation pedestal 1 can be set with a slope of 4 to 7%, and the slope value can also be specifically set as needed to facilitate drainage.

[0048] Embodiment three:

[0049] according to Figure 1 The wind turbine tower pile foundation in the self-weight collapsible loess site shown is different from the first embodiment in that the bottom of the foundation pit is circular and the slope ratio of the foundation pit side slope 4 is 1:0.5.

[0050] In actual use, the foundation pit adopts this technical solution, which makes the electric foundation pit more stable and better ensures the uniform effect of foundation drainage.

[0051] Embodiment 4:

[0052] according to Figure 1The wind turbine tower pile foundation in a self-weight collapsible loess site shown in the figure is different from the first embodiment in that: the first layer of backfill soil 7 is lime soil or cement soil, and the compaction coefficient is not less than 0.95; the second layer of backfill soil 3 has a compaction coefficient of not less than 0.95 and a dry density of not less than 18kN / m 3 of plain soil.

[0053] In actual use, the first layer of backfill soil 7 and the second layer of backfill soil 3 adopt this technical solution, which effectively ensures the waterproofness of the backfill soil. The source of the rammed earth material in the first layer of backfill soil 7 and the second layer of backfill soil 3 is taken from the soil excavated from the foundation pit, which saves resources and reduces the investment in the foundation of the wind turbine tower.

[0054] Embodiment five:

[0055] according to Figure 1 The wind turbine tower pile foundation shown in the self-weight collapsible loess site is different from the embodiment 1 in that the foundation pit slope 4 of the foundation pit adopts two steps, a platform is arranged between the two steps of the foundation pit slope 4, and the hidden water dispersion 5 is arranged on the platform.

[0056] In actual use, the foundation pit adopts two steps, and the hidden water dispersion 5 is set on the platform, so that the water on the wind turbine tower foundation pedestal 1 can be effectively drained to the far end of the foundation, reducing the possibility of foundation flooding and improving the bearing capacity of the foundation piles 9.

[0057] Embodiment six:

[0058] according to Figure 1 The wind turbine tower pile foundation for a self-weight collapsible loess site shown in the figure is different from the fifth embodiment in that the dark scattered water 5 is cast with C10 plain concrete, the thickness of the dark scattered water 5 is 90-200 mm, and the width is 2-4 m; expansion joints are arranged at intervals along the dark scattered water 5 in the annular direction, and the upper surface of the dark scattered water 5 has a slope of 4-7% outward and downward.

[0059] In actual use, the expansion joint has a width of 10 mm and is caulked with asphalt cement. The hidden water dispersion 5 adopts the technical solution to ensure the safety of the present invention under different temperature environments.

[0060] The upper surface of the dark water sprinkling 5 is provided with an outward downward slope, so that the effect of draining water to the far end of the foundation is better. The thickness of the dark water sprinkling 5 and the outward downward slope of the upper surface of the dark water sprinkling 5 can also be set according to actual needs.

[0061] Embodiment seven:

[0062] according to Figure 1The wind turbine tower pile foundation in a self-weight collapsible loess site shown is different from the first embodiment in that the upper surfaces of the first layer of backfill soil 7 and the second layer of backfill soil 3 both have a slope of 4-7% toward the outside of the foundation.

[0063] In actual use, the first layer of backfill soil 7 and the second layer of backfill soil 3 adopt this technical solution, so that the water on the wind turbine tower foundation pedestal 1 can be effectively discharged to the far end of the wind turbine tower foundation pedestal 1, effectively reducing the possibility of foundation flooding.

[0064] The slope of the upper surface of the first layer of backfill soil 7 and the second layer of backfill soil 3 toward the outside of the foundation can also be set according to actual needs.

[0065] Embodiment eight:

[0066] according to Figure 1 The wind turbine tower pile foundation shown in the self-weight collapsible loess site is different from the first embodiment in that the edge of the foundation pit bottom 8 is 0.6 to 1 m away from the bottom edge of the wind turbine tower foundation pedestal 1.

[0067] In actual use, the foundation pit bottom 8 adopts this technical solution, which not only makes the construction convenient, but also expands the area of ​​water dispersion.

[0068] Embodiment nine:

[0069] according to Figure 1 The wind turbine tower pile foundation shown in the self-weight collapsible loess site is different from the embodiment 1 in that it also includes a surface covering layer 2; the surface covering layer 2 is arranged on the second layer of backfill soil 3, and the thickness of the surface covering layer 2 is 0.8m to 1.0m; the upper surface of the surface covering layer 2 is provided with a slope downward.

[0070] In actual use, a surface covering soil layer 2 is laid on the second layer of backfill soil 3. The source of the surface covering soil layer 2 is the surface soil preserved when the foundation pit is excavated. The natural surface 10 enables local plants to adapt quickly and grow rapidly, which is conducive to vegetation reconstruction and effectively reduces the impact of wind turbine tower construction on the fragile ecological environment.

[0071] The upper surface of the ground cover layer 2 is provided with a downward slope to reduce the downward infiltration of water.

[0072] Embodiment ten:

[0073] A construction method for a wind power tower pile foundation on a self-weight collapsible loess site comprises the following steps

[0074] Step 1: Construction of foundation pile 9

[0075] Carry out foundation pile 9 construction, and make the top of foundation pile 9 be located at a preset position under the ground; Step 2: Excavate foundation pit

[0076] Excavate a circular foundation pit with a foundation pit bottom 8, and make the foundation pit slope 4 into two steps, the slope ratio of the two steps is 1:0.5, and a foundation pit slope platform is set between the two steps to connect; preserve the surface soil layer;

[0077] Step 3: Construction of wind turbine tower foundation pedestal 1

[0078] After step 2 is completed, the wind turbine tower foundation pedestal 1 is constructed on the foundation pit bottom 8, and the lower outer edge of the wind turbine tower foundation pedestal 1 is 0.6 to 1 m away from the edge of the foundation pit bottom 8;

[0079] Step 4: First backfill

[0080] After step 3 is completed, the first layer of backfill soil 7 of lime soil or cement soil with a compaction coefficient of not less than 0.95 is used for the first tamping backfill around the wind turbine tower foundation pedestal 1, and the first layer of backfill soil 7 is backfilled to the height of the foundation pit slope platform; the upper surface of the first backfill soil 7 has a slope toward the outside of the foundation;

[0081] Step 5: Construction of hidden water 5

[0082] After step 4 is completed, a hidden water spill 5 is poured on the upper surface of the first layer of backfill soil 7 and the foundation pit slope platform; the upper surface of the hidden water spill 5 is flush with the bottom edge of the cone of the wind turbine tower foundation pedestal 1 and the upper surface of the hidden water spill 5 has an outward downward slope; a gap is provided between the hidden water spill 5 and the wind turbine tower foundation pedestal 1, and expansion joints are provided at intervals along the hidden water spill 5; the gap and the expansion joint are filled with a caulking agent;

[0083] Step 6: Second backfill

[0084] After step 5 is completed, the second layer of backfill soil 3 is compacted layer by layer from the top of the hidden water dispersion 5 to the position 0.8m to 1.0m from the top of the foundation pit, and the top surface of the second layer of backfill soil 3 has a slope toward the outside of the foundation;

[0085] Step 7: Backfilling of topsoil

[0086] After step 6 is completed, the surface soil preserved during the excavation of the foundation pit in step 2 is used to backfill above the compacted second layer of backfill soil 3 to restore the natural surface and revegetate.

[0087] The present invention uses the compacted soil below the surface soil as the first waterproof and drainage measure, uses the outward and downward slope of the cone in the foundation pedestal of the wind turbine tower frame combined with hidden water as the second waterproof and drainage measure, and backfills the surrounding area of ​​the foundation pedestal of the wind turbine tower frame as the third waterproof measure. The pile foundation is waterproofed over a large range, which reduces the possibility of foundation flooding, improves the bearing capacity of the pile foundation, reduces resource consumption, and reduces the investment in the foundation of the wind turbine tower frame. The present invention restores the surface and protects the environment. The present invention adopts a waterproof method that combines the cone in the foundation pedestal of the wind turbine tower frame and hidden water, which changes the existing method of waterproofing the surface. After the foundation construction is completed, the surface soil is used to restore the surface to adapt to plant growth and reduce the impact of wind turbine tower construction on the fragile ecological environment. The present invention uses local materials and saves resources. The present invention utilizes the existing foundation as the rammed earth with a counterweight to have a certain waterproof property, and uses the excavated soil from the foundation pit as the source of the plain soil, ash soil or cement soil rammed earth waterproof material, and also utilizes the surface soil preserved during excavation as the material for restoring the surface, so as to facilitate vegetation reconstruction.

[0088] 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, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

[0089] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0090] In addition, the descriptions of "first", "second", etc. in the present invention are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of the features.

[0091] In the absence of conflicts, technicians in this field can combine the relevant technical features in the above examples according to actual conditions to achieve corresponding technical effects. The specific combinations are not described here one by one.

[0092] The above are only preferred embodiments of the present invention. The present invention will not be limited to the embodiments shown herein, but should conform to the widest scope consistent with the principles and novel features disclosed herein. Any simple modification, equivalent changes and modifications made to the above embodiments according to the technical essence of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A wind power tower pile foundation on a self-weight collapsible loess site, comprising at least a foundation pit, characterized in that: It also comprises a wind turbine tower foundation pedestal (1), a second layer of backfill soil (3), hidden water dispersion (5), a first layer of backfill soil (7) and foundation piles (9); the foundation pit side slope (4) of the foundation pit is stepped; the foundation piles (9) are arranged at the lower part of the foundation pit bottom (8) of the foundation pit, and the top of the foundation piles (9) is flush with the surface of the foundation pit bottom (8); the wind turbine tower foundation pedestal (1) is connected to the foundation pit bottom (8); the first layer of backfill soil (7), hidden water dispersion (5) and the second layer of backfill soil (3) are arranged in sequence from bottom to top around the wind turbine tower foundation pedestal (1); the upper surface of the bottom pedestal of the wind turbine tower foundation pedestal (1) has an outward and downward slope; The wind turbine tower foundation pedestal (1) is a reinforced concrete integrated structure consisting of a short cylinder, a frustum and a small cylinder in order from bottom to top; the upper surface of the hidden water diffuser (5) is flush with the bottom edge of the frustum, and a gap is provided between the hidden water diffuser (5) and the wind turbine tower foundation pedestal (1); The foundation pit slope (4) of the foundation pit adopts two steps, a platform is arranged between the two steps of the foundation pit slope (4), and the hidden water dispersion (5) is arranged on the platform; The hidden sprinkler (5) is cast with C10 plain concrete, and has a thickness of 90 to 200 mm and a width of 2 to 4 m. Expansion joints are arranged at intervals along the circumference of the hidden sprinkler (5), and the upper surface of the hidden sprinkler (5) has a slope of 4 to 7% outward and downward.

2. A wind turbine tower pile foundation for a self-weight collapsible loess site as claimed in claim 1, characterized in that: The bottom of the foundation pit is circular and the slope ratio of the foundation pit side slope (4) is 1:0.

5.

3. A wind turbine tower pile foundation for a self-weight collapsible loess site as claimed in claim 1, characterized in that: The first layer of backfill soil (7) is lime soil or cement soil, and has a compaction coefficient of not less than 0.95; the second layer of backfill soil (3) is plain soil, and has a compaction coefficient of not less than 0.95 and a dry density of not less than 18 kN / m³.

4. A wind turbine tower pile foundation for a self-weight collapsible loess site as claimed in claim 1, characterized in that: The upper surfaces of the first layer of backfill soil (7) and the second layer of backfill soil (3) both have a slope of 4 to 7% toward the outside of the foundation.

5. The wind turbine tower pile foundation for a self-weight collapsible loess site according to claim 1, characterized in that: The edge of the foundation pit bottom (8) is 0.6 to 1 m away from the bottom edge of the wind turbine tower foundation support (1).

6. A wind turbine tower pile foundation for a self-weight collapsible loess site as claimed in claim 1, characterized in that: It also includes a surface soil layer (2); the surface soil layer (2) is arranged on the second layer of backfill soil (3); the thickness of the surface soil layer (2) is 0.8m to 1.0m; and the upper surface of the surface soil layer (2) is provided with a downward slope.

7. A construction method for a wind power tower pile foundation on a self-weight collapsible loess site, characterized in that: The following steps are included Step 1: Construction of foundation piles (9) Carrying out foundation pile (9) construction, and making the top of the foundation pile (9) be located at a preset position below the ground; Step 2: Excavation of foundation pit Excavating a circular foundation pit with a foundation pit bottom (8), and making the foundation pit slope (4) in two steps, the slope ratio of the two steps is 1:0.5, and a foundation pit slope platform is set between the two steps to connect; preserving the surface soil layer; Step 3: Construction of wind turbine tower foundation (1) After step 2 is completed, the wind turbine tower foundation pedestal (1) is constructed on the foundation pit bottom (8), and the lower outer edge of the wind turbine tower foundation pedestal (1) is 0.6 to 1 m away from the edge of the foundation pit bottom (8); Step 4: First backfill After step 3 is completed, a first layer of backfill soil (7) of lime soil or cement soil with a compaction coefficient of not less than 0.95 is used to perform a first compaction backfill around the wind turbine tower foundation pedestal (1), and the first layer of backfill soil (7) is backfilled to the height of the foundation pit slope platform; the upper surface of the first layer of backfill soil (7) has a slope toward the outside of the foundation; Step 5: Construction of hidden water (5) After step 4 is completed, a hidden water spill (5) is poured on the upper surface of the first layer of backfill soil (7) and the foundation pit slope platform; the upper surface of the hidden water spill (5) is flush with the bottom edge of the cone of the wind turbine tower foundation pedestal (1) and the upper surface of the hidden water spill (5) has an outward downward slope; a gap is provided between the hidden water spill (5) and the wind turbine tower foundation pedestal (1), and expansion joints are provided at intervals along the hidden water spill (5); the gap and the expansion joint are filled with a caulking agent; Step 6: Second backfill After step 5 is completed, the second layer of backfill soil (3) is compacted layer by layer from the top of the hidden water dispersion (5) to a position 0.8m to 1.0m from the top of the foundation pit, and the top surface of the second layer of backfill soil (3) has a slope toward the outside of the foundation; Step 7: Backfilling of topsoil After step 6 is completed, the surface soil preserved during the excavation of the foundation pit in step 2 is used to backfill the compacted second layer of backfill soil (3) to restore the natural surface and revegetate.

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