A frost heaving resistant pile foundation for installation of a photovoltaic support in a permafrost region and a construction method thereof

Abstract

The application discloses a kind of anti-frost heaving pile foundation for installing photovoltaic support in frozen soil area and its construction method, belong to frozen soil area pile foundation technical field.The anti-frost heaving pile foundation includes photovoltaic support, prefabricated pipe pile, support connecting section, anti-frost heaving section and fixed section, support connecting section is located above prefabricated pipe pile for connecting photovoltaic support and pile foundation;Anti-frost heaving section is filled with anti-frost heaving material to eliminate the influence of soil frost heaving on engineering, and plays the role of anti-soil frost heaving;Fixed section is located at the lower end of prefabricated pipe pile to improve pile body stability and uplift resistance;The construction method includes: hole digging, hole cleaning, pouring core concrete, installing pile shoe positioner, vibration pile planting, installing centering positioner, filling anti-frost heaving material, sleeve and pouring filling core concrete etc.The application solves the problem of time and labor consumption of the original pile around frost heaving soil replacement technology, and the use of prefabricated pipe pile can save the time spent on pile maintenance, thereby speeding up the construction progress.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of pile foundation in frozen soil area, and particularly relates to a pile foundation for resisting frost heaving for installation of a photovoltaic support in a frozen soil area and a construction method thereof. BACKGROUND

[0002] In China, the region rich in light resources generally overlaps with the seasonal frozen soil region in space, and a large number of photovoltaic power station construction projects are located in the high-latitude seasonal frozen soil regions in the northwest and northeast. In these regions, the freezing depth can reach 2-3 m after the temperature decreases in winter, and the frost heaving deformation can be several centimeters or even tens of centimeters. In spring, the thawing of frozen soil will also cause thawing settlement deformation. The photovoltaic support foundation is a structural component that transmits various actions borne by the support structure for installing photovoltaic modules to the foundation. Compared with the foundation of a building structure, the load borne by the photovoltaic support foundation is relatively small, and the photovoltaic support foundation is not conducive to frost heaving resistance in the frozen soil environment. The photovoltaic support foundation often has a large displacement due to frost heaving and thawing settlement, resulting in wave-shaped deformation of the photovoltaic panel and affecting the photovoltaic power generation efficiency. The photovoltaic power station project has a large area and a large number of foundations, and the maintenance cost is high after the foundation is damaged by frost heaving. The safety and economy of the foundation have a great influence on the entire project.

[0003] At present, the photovoltaic support foundation mainly adopts a pile foundation form, mainly including cast-in-place piles and precast piles. The cast-in-place pile is formed by directly forming a hole at the pile position, then placing a steel reinforcement cage in the hole and pouring concrete. Although the cast-in-place pile has strong adaptability to the ground and high bearing capacity, it has the disadvantages of high cost, high energy consumption, and large amount of mud discharge. The precast pile is processed into a shape in a factory and then driven, pressed or vibrated into the soil on site by a pile sinking equipment or drilled into a hole, and then a smaller precast pile is implanted into the hole filled with filling materials (cement soil, cement mortar, concrete, etc.). The precast pile has the advantages of high bearing capacity, low cost, fast construction speed and short construction period. Compared with the cast-in-place pile with the same bearing capacity, the precast pile can greatly reduce the amount of concrete and steel consumption, save a large amount of cement, sand and steel resources, reduce the discharge of "three wastes", and significantly shorten the construction period. The precast pile is widely used in photovoltaic support foundation projects.

[0004] The frost heaving force of the photovoltaic support foundation must be considered in the photovoltaic power station engineering in the seasonal frozen soil area, and an effective pile foundation structure form and construction method must be adopted to reduce or eliminate the frost heaving force, so as to ensure the safety and stability of the photovoltaic support structure in the frozen soil area. When the prefabricated pile is applied as the photovoltaic support foundation in the current seasonal frozen soil area, the upward frost heaving force is generated in the frozen soil layer. In order to resist the frost heaving force of the photovoltaic support foundation, the frost heaving resistance can only rely on the side friction of the pile below the frozen soil layer. Therefore, the pile length is often directly lengthened, which obviously increases the engineering cost and brings difficulties to the construction. Due to the limitation of cost, the traditional frost heaving prevention and control schemes such as the dynamic compaction method, the replacement method and the pile lengthening method have poor feasibility in the photovoltaic power station construction project. Therefore, the frost heaving force in the frozen soil layer can be obviously reduced by adopting appropriate structure and construction method, the cost is reduced, and the safety of the project is improved. SUMMARY

[0005] The purpose of the present application is to provide an anti-frost heaving pile foundation for photovoltaic support installation in frozen soil area and a construction method thereof, which overcomes the problem of time-consuming and labor-consuming of the pile frost heaving soil replacement technology in the prior art, has a reasonable structure, is convenient to construct, can effectively reduce or eliminate the frost heaving force acting on the pile foundation, and ensures the safety and stability of the photovoltaic support structure in the frozen soil area.

[0006] In order to achieve the above-mentioned purpose, the present application adopts the following technical scheme:

[0007] The anti-frost heaving pile foundation for photovoltaic support installation in frozen soil area comprises a photovoltaic support, a prefabricated pipe pile, a support connecting section, an anti-frost heaving section and a fixing section.

[0008] The support connecting section comprises a steel casing, a pile top end plate, a support bottom plate and a screw rod. The support connecting section is located above the prefabricated pipe pile and is used for connecting the photovoltaic support and the pile foundation. The steel casing is sleeved on the prefabricated pipe pile, and the steel casing is fixedly connected with the pile top end plate. The screw rod is located in the prefabricated pipe pile and penetrates through the reserved hole of the support bottom plate and is exposed above the support bottom plate.

[0009] The anti-frost heaving section comprises an anti-frost heaving layer, a maximum frost depth line and a central positioner. The anti-frost heaving layer is located above the maximum frost depth line. The bottom end of the central positioner is arranged at the position of the maximum frost depth line.

[0010] The fixing section comprises a pile shoe positioner and a pile bottom end plate. The pile shoe positioner is located at the bottom of the prefabricated pipe pile, and the pile shoe positioner is fixedly connected with the pile bottom end plate.

[0011] Further, the inner diameter of the steel casing is greater than the outer diameter of the pile top end plate.

[0012] Further, the support bottom plate is a rectangular steel plate with a reserved hole. The embedding depth of the support bottom plate in the filled core concrete is 1 / 2-2 / 3 of the thickness of the plate.

[0013] Further, the centering positioner comprises an outer cylinder, an inner cylinder and a connecting steel plate, the inner cylinder and the outer cylinder are sleeved, and the inner cylinder and the outer cylinder are connected through the connecting steel plate.

[0014] Further, the outer cylinder and the inner cylinder are of the same height, a gap is reserved between the outer wall of the outer cylinder and the pile hole wall of the pile foundation, the outer diameter of the outer cylinder is the hole diameter of the pile hole minus the reserved gap between the pile hole wall and the outer wall of the outer cylinder; there is a reserved gap between the inner wall of the inner cylinder and the pile outer wall, and the inner diameter of the inner cylinder is the outer diameter of the prefabricated pipe pile plus the reserved gap between the inner wall of the inner cylinder and the pile outer wall.

[0015] Further, the shoe positioner comprises a shoe outer cylinder, a shoe inner cylinder, a shoe connecting steel plate, a bottom plate and a bottom cone tip, the shoe inner cylinder and the shoe outer cylinder are sleeved, the shoe inner cylinder and the shoe outer cylinder are fixedly connected through the shoe connecting steel plate, the bottom cone tip is fixedly connected with the bottom plate, and the pile bottom end plate is fixedly connected with the bottom plate.

[0016] Further, the pile bottom end plate is annular, the outer diameter of the pile bottom end plate is consistent with the diameter of the prefabricated pipe pile, the inner diameter is consistent with the pile diameter of the pile core, and the plate thickness is 10-15mm.

[0017] Further, the anti-frost heaving material 10 is polyurethane foam or EPS foam mixed soil.

[0018] A construction method of an anti-frost heaving pile foundation for installing a photovoltaic support in a frozen soil area comprises the following steps:

[0019] s1, rotary excavating a hole to a designed depth in a to-be-constructed area, the hole diameter is equal to or greater than the pile diameter of the pile foundation by 200-300mm;

[0020] s2, pouring a core insertion concrete into the hole;

[0021] s3, connecting the shoe positioner with the pile bottom end plate to form an integral whole, then pulling the pile body to directly above the hole and aligning the cone tip of the shoe positioner with the center of the hole to preliminarily complete the centering and alignment of the pile body;

[0022] s4, inserting the prefabricated pipe pile into the core insertion concrete;

[0023] s5, after the core insertion concrete is initially set and can better bear the centering positioner, lowering the centering positioner from the top end position of the prefabricated hollow pipe pile to the maximum frost depth position

[0024] s6, filling the anti-frost heaving material;

[0025] s7, waterproofing the pile end and the surrounding side of the pile foundation;

[0026] s8, sequentially connect the pallet, the pull rod and the crossbar to form a core filling mold, and sequentially connect the screw rod, the support bottom plate and the nut to form a support connecting member; the inner wall of the steel casing is welded and connected with the pile top end plate through a welding gun to complete the installation and connection of the steel casing at the pile top position;

[0027] s9, the components assembled in the previous step are poured into a whole through core filling concrete vibration.

[0028] Compared with the prior art, the present application has the following beneficial technical effects:

[0029] The anti-frost heaving pile foundation for installing a photovoltaic support in a frozen soil area comprises a support connecting section, an anti-frost heaving section and a fixing section; the support connecting section comprises a steel casing, an end plate, a support bottom plate and a screw rod; the support connecting section is located above a prefabricated pipe pile and is used for connecting a photovoltaic support and a pile foundation; the inner diameter of the steel casing is larger than the outer diameter of the end plate of the prefabricated pipe pile, and the steel casing is welded and connected with the pile top end plate to improve the shear strength of the pile top end and protect the pile top end, and the steel casing also functions as a pouring mold; the anti-frost heaving layer is located above the maximum frost depth line and between the outer wall of the pile and the wall of the pile hole, and is filled with anti-frost heaving material to eliminate the influence of soil frost heaving on the project and play a role in resisting soil frost heaving; the pile shoe positioner is welded and connected with the pile bottom end plate at the bottom end of the prefabricated pipe pile, is planted into the core filling concrete from the top of the pile hole downwards together with the pile body, forms an integral whole with the core filling concrete around the pile body, plays a role in plugging, guiding and centrally positioning the pile body, and forms an integral whole with the surrounding core filling concrete to significantly improve the stability and anti-pulling force of the pile body.

[0030] Further, the inner diameter of the steel casing is larger than the outer diameter of the pile top end plate, and the shear strength of the pile top end is improved to protect the pile top end, and the steel casing also functions as a pouring mold.

[0031] Further, the depth of the support bottom plate embedded in the core filling concrete is 1 / 2-2 / 3 of the thickness of the support bottom plate, and a more reliable connection strength is provided for the upper connecting member.

[0032] Further, the central positioner comprises an outer cylinder, an inner cylinder and a connecting steel plate, the inner cylinder and the outer cylinder are connected in a sleeve connection, and the inner cylinder and the outer cylinder are connected through the connecting steel plate to reserve sufficient space for the turning up of the core filling concrete during the pile planting process.

[0033] Further, the outer cylinder and the inner cylinder are of the same height, a gap is reserved between the outer wall of the outer cylinder and the wall of the pile hole of the pile foundation, direct contact between the central positioner and the pile hole is avoided as much as possible during the pile planting process to prevent too much soil from the wall of the pile hole from falling and affecting the pile planting process, and a gap is reserved between the inner wall of the inner cylinder and the outer wall of the pile, the inner diameter of the inner cylinder is the outer diameter of the prefabricated pipe pile plus the reserved gap between the inner wall of the inner cylinder and the outer wall of the pile, so that the central positioner can better fall to the frost depth line position during the lowering process.

[0034] The application discloses a pile foundation construction method for anti-frost heaving pile foundation for installing a photovoltaic support in a frozen soil area. BRIEF DESCRIPTION OF DRAWINGS

[0035] Figure 1 It is a pile foundation structure schematic diagram in the embodiment of the application.

[0036] Figure 2 It is a pile foundation filling core mold schematic diagram in the embodiment of the application.

[0037] Figure 3 It is a pile foundation filling core mold top view in the embodiment of the application.

[0038] Figure 4 It is a pile foundation A-A sectional view in the embodiment of the application.

[0039] Figure 5 It is a pile foundation B-B sectional view in the embodiment of the application.

[0040] Figure 6 It is a pile foundation C-C sectional view in the embodiment of the application.

[0041] Figure 7 It is a pile foundation D-D sectional view in the embodiment of the application.

[0042] Figure 8 It is a pile foundation E-E sectional view in the embodiment of the application.

[0043] Figure 9 It is a pile shoe positioner schematic detail view in the embodiment of the application.

[0044] Figure 10 It is a pile head schematic detail view in the embodiment of the application.

[0045] In the diagram, 1—Photovoltaic support; 2—Nut; 3—Support base plate; 4—Crossbar; 5—Steel casing; 6—Tie rod; 7—Core-filling concrete; 8—Screw rod; 9—Support plate; 10—Frost-resistant material; 11—Precast pipe pile; 12—Maximum frost depth line; 13—Pile core; 14—Intercalated concrete; 15—Pile hole; 16—Pile shoe locator; 16—1. Pile shoe outer cylinder; 16—2. Pile shoe connecting steel plate; 16—3. Pile shoe inner cylinder; 16 —4. Base plate; 16—5. Bottom cone tip; 17—Support connecting section; 18—Frost heave resistant section; 19—Fixing section; 20—1. Pile top plate; 20—2. Pile bottom plate; 21—Centering locator; 21—1. Outer cylinder; 21—2. Inner cylinder; 21—3. Internal filling material; 21—4. Connecting steel plate; 22—Ground surface; 23—1. Plain concrete cushion layer; 23—2. Polyurethane waterproof coating; 23—3. Waterproof membrane; 24—Soil around the pile. Detailed Implementation

[0046] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0047] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0048] The present invention provides an anti-frost heave pile foundation for photovoltaic bracket installation, comprising a bracket connection section 17, an anti-frost heave section 18, and a fixing section 19;

[0049] The support connection section 17 includes a steel casing 5, a pile top plate 20-1, a support base plate 3, and a screw rod 8. The support connection section 17 is located above the precast pipe pile 11 and is used to connect the photovoltaic support 1 and the pile foundation. The steel casing 5 is sleeved on the precast pipe pile 11 and is fixedly connected to the pile top plate 20-1 to improve the shear strength of the pile top and protect the pile top. It also serves as a casting mold. The screw rod 8 is placed inside the precast pipe pile 11, passes through the reserved hole in the support base plate 3, protrudes above the support base plate 3, and is cast into a whole with the filling concrete 7. The screw rod 8 is U-shaped.

[0050] The frost-resistant section 18 includes an frost-resistant layer, a maximum frost line 12, and a centering locator 21. The frost-resistant section 18 is located below the ground surface 22 and above the maximum frost line 12. The frost-resistant layer is located above the maximum frost line 12 and is filled with frost-resistant material 10. Through the compressibility of the frost-resistant material 10 when the soil frosts, the impact of soil frost heave on the project is eliminated, and the frost-resistant locator 21 is located at the maximum frost line 12.

[0051] The fixed section 19 includes a pile shoe locator 16 and a pile bottom end plate 20-2. The fixed section 19 is located below the frost-resistant section 19. The pile shoe locator 16 is located at the bottom of the precast pipe pile 11. The pile shoe locator 16 is welded to the pile bottom end plate 20-2 and is inserted into the core concrete 14 from the top of the pile hole 15 along with the pile body. It forms an integral whole with the core concrete 14 around the pile body. The two work together to seal and guide the pile body and center the pile body. It forms an integral whole with the surrounding core concrete 14, which significantly improves the stability and pull-out resistance of the pile body.

[0052] Specifically, the steel casing 5 is a seamless steel pipe with a wall thickness of 5-10mm. Its inner diameter is 2-3mm larger than the outer diameter of the pile top plate 20-1. It is welded to the pile top plate 20-1 to improve the shear strength of the pile top and protect the pile top. It also serves as a casting mold.

[0053] The support base plate 3 is a rectangular steel plate with pre-drilled holes, with a thickness of 10-20mm. The depth of the embedded core concrete 7 is 1 / 2-2 / 3 of the plate thickness, providing a more reliable connection strength for the upper connecting components.

[0054] The support connection section also includes a core filling mold, which includes a crossbar 4, a tie rod 6, and a support plate 9. The crossbar 4 is welded to the top plate 20-1 of the pile. The tie rod 6 is located between the crossbar 4 and the support plate 9, and is connected to the crossbar 4 and the support plate 9 at the top and bottom, respectively. The support plate 9 is located 0.3-0.5m below the ground elevation 22. The crossbar 4, tie rod 6, and support plate 9 are welded together in sequence to form a casting mold inside the precast pipe pile 11 for pouring the core filling concrete 7.

[0055] The frost-resistant layer is located above the maximum frost depth line 12 and is situated between the outer wall of the pile and the wall of the pile hole 15. The frost-resistant layer is filled with frost-resistant material 10. Through the compressibility of the frost-resistant material 10 when the soil frosts, the impact of soil frost heave on the project is eliminated, and the frost-resistant material 10 plays a role in resisting soil frost heave. The frost-resistant material 10 is polyurethane foam or EPS foam mixed soil, etc., and the filling method is from bottom to top.

[0056] The centering locator 21 includes an outer cylinder 21-1, an inner cylinder 21-2, and a connecting steel plate 21-4, which enhances the centering and positioning function of the pile. The inner cylinder 21-2 and the outer cylinder 21-1 are connected by three connecting steel plates 21-4 welded together at 120° to each other. This provides sufficient space for the upward turning of the core concrete 14 during the pile planting process. The outer cylinder 21-1 and the inner cylinder 21-2 are of the same height, with a height of 200-300mm and a wall thickness of 10-15mm. A gap is reserved between the wall of pile hole 15 and the outer wall of outer cylinder 21-1. The outer diameter of outer cylinder 21-1 is the diameter of pile hole 15 minus the reserved gap between the wall of pile hole 15 and the outer wall of outer cylinder 21-1. The reserved gap between the wall of pile hole 15 and the outer wall of outer cylinder 21-1 is 20-30mm. This gap is designed to avoid direct contact between the centering locator 21 and pile hole 15 during pile planting, so as to prevent excessive soil from falling off the wall of pile hole 15 and affecting pile planting. The process involves a pre-reserved gap between the inner wall of the inner cylinder 21-2 and the outer wall of the pile. The inner diameter of the inner cylinder 21-2 is the outer diameter of the precast pipe pile 11 plus the pre-reserved gap between the inner wall of the inner cylinder 21-2 and the outer wall of the pile. The pre-reserved gap between the inner wall of the inner cylinder 21-2 and the outer wall of the pile is 5-10mm. This gap allows the centering locator 21 to fall more effectively to the frost depth line during the lowering process. The connecting steel plate 21-4 is a 10-15mm thick steel plate.

[0057] The hollow part inside the centering locator 21 is pre-filled with internal filling material 21-3 to prevent uneven filling of the anti-frost heave material 10 at the maximum frost depth line 12 due to the setting of the centering locator 21, thus better ensuring the realization of the anti-frost heave function. The internal filling material 21-3 inside the locator is the same material as the anti-frost heave material 10 filled in the anti-frost heave layer. The centering locator 21 is placed downwards from the pile head to the maximum frost depth line 12 1-2 hours after the lower concrete has initially set, avoiding the problem of the centering locator 21 sinking into the concrete due to insufficient concrete strength, and further ensuring the realization of the pile body centering positioning function. The precast pipe pile 11 of the anti-frost heave section 18 needs to be coated with asphalt or industrial petroleum jelly on its outer wall before pile driving. This can effectively protect the precast pipe pile 11 from the corrosion of the working environment and reduce the frictional resistance around the pile. Then it is inserted into the pile hole 15 and comes into contact with the anti-frost heave material 10 around the pile body to work together.

[0058] The pile shoe locator 16 includes an outer cylinder 16-1, an inner cylinder 16-3, a connecting steel plate 16-2, a base plate 16-4, and a bottom cone tip 16-5, which adds the function of centering and positioning the pile body. The outer cylinder 16-1 of the pile shoe is a hollow cylinder with an arc-shaped bottom (the arc angle α should preferably be 15°-30°). The outer cylinder 16-1 is formed by welding the bottom of a cylindrical steel plate to the top of an arc-shaped cylindrical steel plate (the arc angle α should preferably be 15°-30°). The thickness of both the cylindrical and arc-shaped steel plates is 10-15 mm. The height ratio of the arc-shaped and cylindrical steel plates in the vertical direction should preferably be 1 / 10-1 / 15. The inner cylinder 16-3 of the pile shoe is a hollow cylinder made of round steel plate (the plate thickness is 10-15 mm). The inner cylinder 16-3 is the same as the outer cylinder 16-1. The pile shoe has a height (preferably 200-300mm). The inner cylinder 16-3 and outer cylinder 16-1 are welded together by a connecting steel plate 16-2. The connecting steel plate 16-2 is a trapezoidal steel plate (gradient equal to the arc α, 15°-30°, plate thickness 10-15mm). The bottom plate 16-4 is welded to the bottom of the inner cylinder 16-3. The bottom plate 16-4 is a solid cylinder made of round steel plate (plate thickness 10-15mm). The pile bottom end plate 20-2 is welded to the bottom plate 16-4. The pile bottom end plate 20-2 is a ring-shaped steel plate made of steel. The outer diameter of the bottom end plate 20-2 of the pile is the same as the diameter of the precast pipe pile 11, and the inner diameter is the same as the diameter of the pile core 13. The plate thickness is 10-15mm. The bottom cone tip 16-5 is welded to the bottom plate 16-4. The bottom cone tip 16-5 is a hollow cone (the cone angle β should be 30°-60°). The bottom cone tip 16-5 is made of steel plate (plate thickness is 10-15mm). The setting of the bottom cone tip 16-5 allows the pile body to be better inserted into the core concrete 14 during the pile planting process, and allows the core concrete 14 to better flow upward through the space reserved by the pile shoe locator 16. The bottom cone tip 16-5 is high. The degree is tan(90°﹣0.5*cone angle β)*the horizontal distance from the welding connection position of the bottom plate 16-4 and the bottom cone tip 16-5 to the center of the pipe pile. The height of the pile shoe locator 16 is the height of the outer cylinder 16-1 of the pile shoe + the height of the bottom cone tip 16-5. After the pile shoe locator 16 is welded to the precast pipe pile 11, it is inserted into the core concrete 14 from the top of the pile hole 15 along with the pile body, and forms an integral whole with the core concrete 14 around the pile body. The two work together to seal and guide, as well as center the pile body, and form an integral whole with the surrounding core concrete 14, which significantly improves the stability and pull-out resistance of the pile body.

[0059] The core concrete 14 is fine aggregate concrete.

[0060] This invention also provides a construction method for frost-resistant pile foundations for photovoltaic support installation in seasonally frozen soil areas, comprising the following steps:

[0061] Step 1: Rotary drilling: Dry drilling is carried out in the soil layer using the auger bit of the drilling rig to drill a hole to the designed depth. The hole diameter is greater than or equal to the pile diameter by 200mm-300mm.

[0062] Step 2, Hole Cleaning: After replacing the auger bit of the drilling rig with a hole cleaning bit, use the drilling rig to clean up the soil clods that have fallen to the bottom of the hole due to excavation and the residue caused by rotary drilling at the bottom of the hole;

[0063] Step 3: Pouring the core concrete 14: Use a concrete pump truck to pour the core concrete 14 into the hole through the tremie pipe. The required amount of concrete should be determined in advance by calculating the volume of the precast pipe pile 11 below the maximum frost depth line 12 and the resulting rise in the core concrete 14 after the pile is installed. This ensures that the height of the core concrete 14 after the pile is installed is below the maximum frost depth line 12. It should be noted that a height difference of 5-10cm should be reserved between the core concrete 14 and the maximum frost depth line 12 to ensure that the antifreeze material 10 is fully filled in the antifreeze layer.

[0064] Step 4: Install the pile shoe locator 16 and center it: Weld the pile shoe locator 16 to the bottom end plate 20-2 of the pile with a welding gun to form a whole, thereby realizing the addition of the pile body centering and positioning function. Then, pull the pile body to the top of the pile hole with the mechanical arm of the construction machine and make the cone tip of the pile shoe locator 16 aligned with the center of the pile hole, thus completing the initial centering and positioning of the pile body.

[0065] Step 5, Vibration Pile Installation: Based on Step 4, the construction machine repeatedly presses and pulls the precast pipe pile 11, slowly inserting it into the core concrete 14. This ensures that the pile body drives the core concrete 14 around the pile to vibrate together during the pile installation process, so that the core concrete 14 around the pile is fully vibrated and promotes a tight bond between the core concrete 14 around the pile and the pile body. It should be noted that before the pile installation, the precast pipe pile 11 of the anti-frost heave section 18 should be coated with asphalt or industrial petroleum jelly.

[0066] Step Six: Install the centering locator 21: Based on Step Five, after the concrete has initially set for 1-2 hours and has reached a certain strength to support the centering locator 21, the inner cylinder 21-2 of the centering locator 21 is placed on the top of the precast hollow pipe pile 11. The pile is then slowly lowered from the top of the precast hollow pipe pile 11 to the maximum frost depth line 12 using a rope. This significantly enhances the centering and positioning function of the pile body, avoids the problem of uneven filling of the anti-frost heave material 10 due to the tilt of the pile body, and ensures the realization of the anti-frost heave function of the pile body.

[0067] Step 7: Fill with anti-frost heave material 10: Based on step 6, fill and vibrate the anti-frost heave material 10 into the pile hole from bottom to top to form an anti-frost heave layer, ensuring that the anti-frost heave material 10 is filled from the maximum frost depth line 12 to the ground surface.

[0068] Step 8, Waterproofing: After step 7 is completed, a 100mm thick ring-shaped plain concrete pad 23-1 should be laid within 300mm of the perimeter of the pipe pile end. Then, a waterproof membrane 23-3 should be laid on the smoothed plain concrete pad 23-1. Finally, polyurethane waterproof coating 23-2 should be applied to the laid waterproof membrane 23-3 with a brush to form a 2-3mm thick polyurethane waterproof layer. A ring of waterproof sealant should be applied to the interface between the plain concrete pad 23-1 and the pile end with a brush. It should be noted that the polyurethane coating needs to be applied in multiple coats. The next coat should be applied only after the previous polyurethane waterproof coating 23-2 has dried.

[0069] Step 9: Install the bracket connecting components and the core filling mold: After step 8 is completed, first weld the support plate 9, tie rod 6, and cross bar 4 together in sequence using a welding gun to form the core filling mold, and then connect the screw 8, bracket base plate 3, and nut 2 together in sequence to form the bracket connecting components.

[0070] Step 10, Sleeve: Weld the inner wall of the steel casing 5 to the top plate 20-1 of the pile using a welding gun to complete the installation and connection of the steel casing 5 at the top of the pile, thereby improving the shear strength at the top of the pile.

[0071] Step 11, Pouring the core-filling concrete 7: The components assembled in Steps 9 and 10 are poured into a whole by manually transporting and vibrating the core-filling concrete 7.

[0072] This invention provides a simple, rationally designed, and conveniently constructed anti-frost heave pile foundation for photovoltaic support installation in permafrost regions, effectively improving construction efficiency. It employs a vibratory pile planting method, allowing precast pipe piles to be vibrated and inserted into the pile holes simultaneously, ensuring sufficient compaction of the surrounding core concrete during the planting process, promoting better interlocking and operation between the pile body and the surrounding core concrete. An improvement on the traditional pile planting method involves filling the pile holes from the maximum frost depth line to the ground surface with an anti-frost heave material to form an anti-frost heave layer. Utilizing the compressibility of the anti-frost heave material during soil frost heave, the impact of soil frost heave on the project is eliminated. This solves the time-consuming and labor-intensive problem of replacing frost-susceptible soil around the piles using traditional methods. Furthermore, the use of precast pipe piles saves time spent on pile curing, thereby increasing efficiency. Accelerated construction progress; by adding steel casings at the pile heads and using them as casting molds and support connectors to pour the core-filling concrete to form a whole, the shear strength of the pile heads is improved; the improvement of the pile shoe locator adds a new function of centering the pile body to its original function of sealing and diverting, which minimizes the tilting of the precast pipe piles during the pile planting process, and the arc design of the pile shoe locator also ensures that the pile body can be smoothly implanted during the pile planting process; the setting of the centering locator, on the one hand, significantly enhances the function of centering the pile body by aligning with the pile shoe locator at two points and is more conducive to ensuring the quality of the project, and on the other hand, the anti-frost heave material pre-filled in the centering locator also ensures that the maximum frost depth line of the anti-frost heave function is achieved.

Claims

1. A frost-resistant pile foundation for photovoltaic support installation in permafrost regions, characterized in that, It includes a photovoltaic support (1), a precast pipe pile (11), a support connection section (17), a frost-resistant section (18), and a fixing section (19). The support connection section (17) includes a steel casing (5), a pile top plate (20-1), a support bottom plate (3), and a bolt (8); the steel casing (5) is sleeved on the precast pipe pile (11), and the steel casing (5) is fixedly connected to the pile top plate (20-1); the bolt (8) is located inside the precast pipe pile (11), passes through the reserved hole in the support bottom plate (3), and protrudes above the support bottom plate (3); The support connection section (17) also includes a core filling mold, which includes a crossbar (4), a tie rod (6) and a support plate (9); the crossbar (4) is welded to the top plate (20-1) of the pile; the tie rod (6) is set between the crossbar (4) and the support plate (9), and is connected to the crossbar (4) and the support plate (9) at the top and bottom respectively; The frost-resistant section (18) includes an frost-resistant layer, a maximum frost depth line (12), and a centering locator (21); the frost-resistant layer is located above the maximum frost depth line (12); the bottom of the centering locator (21) is located at the position of the maximum frost depth line (12); The fixed section (19) includes a pile shoe locator (16) and a pile bottom end plate (20-2). The pile shoe locator (16) is located at the bottom of the precast pipe pile (11) and is fixedly connected to the pile bottom end plate (20-2). The support base plate (3) is a rectangular steel plate with pre-drilled holes. The depth to which the support base plate (3) is embedded in the core-filling concrete (7) is 1 / 2 to 2 / 3 of the thickness of the support base plate (3). The centering positioner (21) includes an outer cylinder (21-1), an inner cylinder (21-2), and a connecting steel plate (21-4). The inner cylinder (21-2) and the outer cylinder (21-1) are sleeved together, and the inner cylinder (21-2) and the outer cylinder (21-1) are connected by the connecting steel plate (21-4). The outer cylinder (21-1) and the inner cylinder (21-2) are of the same height. There is a gap between the outer wall of the outer cylinder (21-1) and the wall of the pile hole (15) of the pile foundation. The outer diameter of the outer cylinder (21-1) is the diameter of the pile hole (15) minus the gap between the wall of the pile hole (15) and the outer wall of the outer cylinder (21-1). There is a gap between the inner wall of the inner cylinder (21-2) and the outer wall of the pile. The inner diameter of the inner cylinder (21-2) is the outer diameter of the precast pipe pile (11) plus the gap between the inner wall of the inner cylinder (21-2) and the outer wall of the pile. The pile shoe locator (16) includes an outer cylinder (16-1), an inner cylinder (16-3), a connecting steel plate (16-2), a base plate (16-4), and a bottom cone (16-5). The inner cylinder (16-3) is sleeved with the outer cylinder (16-1). The inner cylinder (16-3) and the outer cylinder (16-1) are fixedly connected by the connecting steel plate (16-2). The bottom cone (16-5) is fixedly connected with the base plate (16-4). The bottom end plate (20-2) is fixedly connected with the base plate (16-4).

2. The anti-frost heave pile foundation for photovoltaic support installation in permafrost areas according to claim 1, characterized in that, The inner diameter of the steel casing (5) is larger than the outer diameter of the pile top plate (20-1).

3. The anti-frost heave pile foundation for photovoltaic support installation in permafrost areas according to claim 1, characterized in that, The bottom end plate (20-2) of the pile is circular. The outer diameter of the bottom end plate (20-2) is the same as the diameter of the precast pipe pile (11), and the inner diameter is the same as the diameter of the pile core (13). The plate thickness is 10-15mm.

4. The anti-frost heave pile foundation for photovoltaic support installation in permafrost areas according to claim 1, characterized in that, The anti-frost heave material (10) is polyurethane foam or EPS foam mixed soil.

5. A construction method for anti-frost heave pile foundations for photovoltaic support installation in permafrost regions, based on the anti-frost heave pile foundation for photovoltaic support installation in permafrost regions as described in claim 1, characterized in that... Includes the following steps: s1. Rotary drilling is carried out in the area to be constructed to the design depth, and the diameter of the drilled hole is 200-300mm larger than the diameter of the pile foundation. s2, pour core concrete into the hole (14); s3. Connect the pile shoe locator (16) to the bottom end plate (20-2) of the pile and form a whole. Then pull the pile body to the top of the pile hole and make the cone tip of the pile shoe locator (16) align with the center of the pile hole to initially complete the centering and alignment of the pile body. s4. Insert the precast pipe pile (11) into the core concrete (14); s5. After the core concrete (14) has initially set to a level that can better support the centering locator (21), the centering locator (21) is lowered from the top of the precast hollow pipe pile (11) to the position of the maximum frost depth line (12). s6, Fill with anti-frost heave material (10); s7. Waterproofing treatment is applied to the periphery of the pile ends of the pile foundation; s8. Connect the support plate (9), tie rod (6), and cross bar (4) in sequence to form a core filling mold. Then connect the screw (8), bracket base plate (3), and nut (2) in sequence to form a bracket connection component. Weld the inner wall of the steel casing (5) to the top plate (20-1) of the pile using a welding gun to complete the installation connection of the steel casing (5) at the top of the pile. s9. The components assembled in the previous step are poured into a whole by vibrating and tamping the core-filling concrete (7).

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