Working method of self-locking sleeve isolation structure for preventing frost pull-out of pile foundations in seasonally frozen soil areas

Abstract

This invention discloses a working method for a self-locking sleeve isolation structure for preventing frost pull-out of pile foundations in seasonally frozen soil areas. The self-locking sleeve isolation structure includes a displacement cylinder and a fixed cylinder. A drive groove is formed on the outer wall of the displacement cylinder, and a first transmission groove is formed inside the fixed cylinder. A first rack is provided in the drive groove, and a first gear is provided in the first transmission groove. A rod-placement box is fixed to the top of the first transmission groove, and a fixed cone is slidably connected inside the rod-placement box. A second rack is fixed to the bottom of the fixed cone. The first gear is connected to the second rack via a gear bevel gear reversing transmission assembly. A through rod is slidably connected inside the fixed cone, and a second limiting block is fixed to the side wall of the through rod. The second limiting block is slidably connected to a limiting groove formed on the rod-placement box. A reinforcing rod is hinged to the through rod, and a first collar is sleeved on the through rod. A second collar is sleeved on the reinforcing rod, and a support rod is hinged to the second collar. The other end of the support rod is hinged to the outside of the first collar. This invention achieves stable and reliable pile foundation isolation and protection.

Description

[0001] This invention application is a divisional application of the parent application "Self-locking sleeve isolation structure and construction method for preventing pile foundation frost pull-out in seasonally frozen soil areas". The application date of the parent application is February 14, 2025, and the application number is 2025101633550. Technical Field

[0002] This invention relates to the field of construction technology for preventing and controlling frost pull-out of pile foundations, and in particular to a self-locking sleeve isolation structure and construction method for preventing frost pull-out of pile foundations in seasonally frozen soil areas. Background Technology

[0003] Frost pull-out is a key issue affecting the stability of lightweight shallow foundations in cold regions, and it remains unresolved. From the perspective of the interaction mechanism between frozen soil and pile foundations, pile foundations are mainly subjected to the combined effects of horizontal frost heave force, normal frost heave force, and tangential frost heave force. In the evolution of pile foundation frost pull-out, the decrease in winter temperature causes the soil to freeze, and the soil around the pile freezes together with the pile foundation, forming a frost heave effect. Under the action of tangential frost heave force, the pile foundation is gradually pulled up. In summer, the increase in temperature causes the soil to thaw, and the shallow thawed soil begins to recede. However, due to the presence of frictional resistance in the deeper soil layers, the pile foundation does not completely recede with the soil, resulting in a certain residual vertical displacement. With the continuous cycle of this process, the amount of frost pull-out accumulates year by year, which may eventually lead to pile foundation instability. Therefore, how to effectively reduce the pile foundation pull-out caused by the accumulation of frost pull-out has become an important problem that urgently needs to be solved in the field of pile foundation mechanics research in cold regions.

[0004] The casing isolation method is a technique that suppresses frost pull-out effects by reducing the interaction between the pile foundation and seasonally frozen soil. It has been widely used due to its advantages such as simple construction, low maintenance costs, and environmental friendliness. The core idea is to install a casing around the pile foundation to isolate it from direct contact with the surrounding sub-frozen soil. This significantly reduces the frost heave friction of the surrounding soil, thereby reducing the tangential frost heave force on the pile foundation, decreasing frost pull-out displacement, and inhibiting the accumulation of frost pull-out. However, under repeated freeze-thaw cycles, the casing is gradually pulled out, and its isolation effect and frost pull-out control efficiency are significantly weakened. Currently, no technology has been reported on optimizing the frost pull-out resistance durability of the pile-outer casing. Therefore, there is an urgent need to develop a new type of casing isolation structure with high durability to ensure the control of frost pull-out effects while meeting long-term engineering life requirements, providing a more reliable technical guarantee for the stability of pile foundations in cold regions. Summary of the Invention

[0005] The purpose of this invention is to address the technical deficiencies in the existing technology by providing a self-locking sleeve isolation structure for preventing the freezing and pulling out of pile foundations in seasonally frozen soil areas.

[0006] Another objective of this invention is to provide a working method for the self-locking sleeve isolation structure for preventing frost pull-out of pile foundations in seasonally frozen soil areas.

[0007] Another objective of this invention is to provide a construction method for a self-locking sleeve isolation structure for preventing frost pull-out of pile foundations in seasonally frozen soil areas.

[0008] The technical solution adopted to achieve the purpose of this invention is:

[0009] A self-locking sleeve isolation structure for preventing frost pull-out of pile foundations in seasonally frozen soil areas includes a hollow fixed cylinder and a displacement cylinder that is slidably sleeved inside the fixed cylinder, with the top surface of the fixed cylinder located below the seasonally frozen soil layer.

[0010] The inner wall of the fixed cylinder is provided with one or more first transmission grooves, and the outer wall of the displacement cylinder is provided with one or more drive grooves. The drive grooves and the first transmission grooves are arranged opposite to each other. Each drive groove is equipped with a first rack, and each first transmission groove is equipped with a first gear. When the first rack moves upward, it meshes with the first gear.

[0011] A horizontally extending rod holder is fixed to the top of the first transmission groove. The end opening of the rod holder communicates with an opening formed on the fixed cylinder. A fixed cone is slidably connected inside the rod holder. A second rack is fixed to the side of the fixed cone. The first gear is connected to the second rack via a gear bevel gear reversing transmission assembly.

[0012] The front end of the fixed cone is provided with a second transmission groove, and the through rod is slidably connected in the second transmission groove. The outer end of the through rod passes through the end opening of the second transmission groove, and the inner end of the through rod is connected in the second transmission groove by a first spring. A second limiting block is fixed on the side wall of the through rod. The second limiting block passes through the clearance groove opened on the fixed cone and is slidably connected in the limiting groove opened on the rod holder.

[0013] The end of the through rod extending outside the second transmission groove is hinged with multiple reinforcing rods. The through rod is fitted with a first collar at the position outside the second transmission groove. Each reinforcing rod is fitted with a second collar that slides with it. Each second collar is hinged with a support rod, and the other end of the support rod is hinged to the outside of the first collar.

[0014] In the above technical solution, the bottom of the fixed cylinder is slidably connected to the outside of the displacement cylinder through a slider groove structure.

[0015] In the above technical solution, the second rack is slidably connected to the through groove opened in the side wall of the rod holder.

[0016] In the above technical solution, the through rod is slidably connected to the second transmission groove through a slider and a sliding groove structure.

[0017] In the above technical solution, the gear bevel gear reversing transmission assembly includes a second gear, a third gear, a fourth gear, a first bevel gear, a second bevel gear, and a fifth gear. The second gear is rotatably connected to the side wall of the first transmission groove via a bearing and rod assembly. The third gear meshes with one side of the second gear. The third gear and the first gear are located on opposite sides of the second gear. The third gear meshes with the fourth gear. The fourth gear is coaxially welded with a first bevel gear rotatably connected to the side wall of the first transmission groove. The tooth surface of the first bevel gear meshes with a second bevel gear arranged perpendicular to the first bevel gear. The top of the second bevel gear is welded with a fifth gear rotatably connected to the top wall of the first transmission groove. The fifth gear meshes with the second rack.

[0018] In the above technical solution, the bottom of the first rack is provided with an adjustment component. The adjustment component includes a connecting rod welded to one side of the first rack. A first limiting block is welded to the end of the connecting rod away from the first rack. The first limiting block is slidably connected to a slot formed in the side wall of the displacement cylinder. A plurality of second springs are connected between the first rack and the inner side wall of the drive groove.

[0019] The cross-sectional shape of the teeth of the first rack is trapezoidal, the top surface of the teeth of the first rack is a plane, and the bottom surface of the teeth of the first rack is an inclined plane.

[0020] In the above technical solution, multiple reinforcing rods are distributed in an umbrella shape and hinged to the end of the through rod.

[0021] Another aspect of the present invention includes a method for operating the self-locking sleeve isolation structure for preventing frost pull-out of pile foundations in seasonally frozen soil areas, comprising the following steps:

[0022] The pile foundation is constructed inside the displacement cylinder. When the displacement cylinder is lifted by the tangential frost heave force, the displacement cylinder moves upward, and the first rack also moves upward and meshes with the first gear, driving the first gear to rotate. The first gear drives the second rack to move outward through the gear bevel gear reversing transmission assembly. Then, the second rack drives the fixed cone to move towards the opening end of the rod holder. When the second limiting block contacts the side wall of the limiting groove, the through rod stops moving forward. The fixed cone continues to move forward under the drive of the second rack. At this time, the first spring will be compressed and shortened. The front end of the fixed cone presses against the first collar, causing it to slide outward along the through rod, driving the reinforcing rod to slide outward and break free from the constraint of the rod holder. The umbrella-shaped reinforcing rods pass through the opening on the fixed cylinder and unfold to form an anchor.

[0023] Another aspect of the present invention includes a construction method for the self-locking sleeve isolation structure for preventing frost pull-out of pile foundations in seasonally frozen soil areas, comprising the following steps:

[0024] Step S1: Determine the pile location and the dimensions of the fixed cylinder and the displacement cylinder;

[0025] Step S2: Dig drainage ditches around the construction area or at a suitable location, and use a drilling machine with a drill bit of the same diameter as the fixed cylinder to perform drilling operations. Stop drilling after drilling to the designed depth of the fixed cylinder.

[0026] Step S3: Hoist the fixed cylinder into the borehole formed in step S2, and ensure that the top surface of the fixed cylinder is not higher than the maximum seasonal freezing depth.

[0027] Step S4: Drill a hole using a drill bit with the same diameter as the displacement cylinder. Stop drilling after reaching the designed depth of the pile foundation.

[0028] Step S5, clean the hole;

[0029] Step S6: Inspect and accept the quality of the formed holes;

[0030] Step S7: The displacement cylinder is hoisted into the borehole formed in step S4 and fixed in place;

[0031] Step S8: Lower the steel cage into the hole, then prepare the concrete pouring pipe and lower it into the hole. Before pouring, ensure that the bottom of the pile is clean, free of water and sediment, and then pour concrete using the pouring pipe to complete the pile foundation construction.

[0032] Compared with the prior art, the beneficial effects of the present invention are:

[0033] 1. This invention precisely senses the tangential frost heave displacement experienced by the displacement cylinder in seasonally frozen soil regions, and drives the reinforcing rod to extend and unfold from the opening on the fixed cylinder to form an anchorage. This innovative control structure can significantly reduce the deformation of pile foundations caused by freeze-thaw cycles, thereby greatly improving the stability and durability of the pile foundation. Compared with traditional methods, this technology achieves dynamic monitoring and coordinated automatic control of pile foundation frost heave displacement, reducing potential risks caused by untimely monitoring or inaccurate adjustments.

[0034] 2. Through its cleverly designed adjustment components and first rack, this invention enables the structure to flexibly respond to frost heave displacements of varying sizes and directions, ensuring stable and effective control under diverse and complex freeze-thaw cycles. This design not only improves the precision of control but also significantly enhances the adaptability and flexibility of the structure, making it more suitable for complex and variable seasonal permafrost environments compared to traditional fixed protection methods.

[0035] 3. The inclusion of the through rod, the first spring, and the reinforcing rod further enhances the fixing force of the fixing cone, providing strong support for its fixation. This not only further strengthens the fastening effect of the fixing cone, ensuring the pile foundation remains stable even under extreme freeze-thaw conditions, but also effectively improves the safety and reliability of the overall structure. Compared to the limited fixing force and easy loosening issues of traditional technologies, this technology achieves more stable and reliable pile foundation isolation and protection through automatic adjustment and reinforcement of the fixing mechanism. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0037] Figure 2 This is a schematic front cross-sectional view of the entire invention;

[0038] Figure 3 for Figure 2 Enlarged view of point A in the middle;

[0039] Figure 4 This is a schematic diagram of the meshing of the gear bevel gear reversing transmission assembly of the present invention;

[0040] Figure 5 This is a schematic diagram of the connection structure of the fifth gear, the rod holder, and the through groove in this invention;

[0041] Figure 6 This is an isometric schematic diagram of the fixed cone of the present invention;

[0042] Figure 7 This is a front sectional view of a fixed cone;

[0043] Figure 8 This is a cross-sectional schematic diagram of the connection structure of the through rod, the fixed cone, and the rod holder box.

[0044] Figure 9 This is a flowchart of the construction method.

[0045] In the diagram: 1. Fixed cylinder; 2. Displacement cylinder; 3. Drive groove; 4. First transmission groove; 5. First rack; 6. Rod holder; 7. Fixed cone; 8. Connecting rod; 9. First limiting block; 10. Second spring; 11. Second rack; 12. Through groove; 13. First gear; 14. Second gear; 15. Third gear; 16. Fourth gear; 17. First bevel gear; 18. Second bevel gear; 19. Fifth gear; 20. Second transmission groove; 21. Through rod; 22. Limiting groove; 23. Second limiting block; 24. First spring; 25. Reinforcing rod; 26. First collar; 27. Second collar; 28. Support rod; 29. ​​Pile foundation; 30. Clearance groove; 31. Opening. Detailed Implementation

[0046] The present invention will be further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0047] Example 1

[0048] like Figures 1-8 As shown, a self-locking sleeve isolation structure for preventing frost pull-out of pile foundations in seasonally frozen soil areas includes a hollow fixed cylinder 1 and a displacement cylinder 2 slidably sleeved inside the fixed cylinder 1; the top surface of the fixed cylinder 1 is located below the seasonally frozen soil layer, the inner diameter of the fixed cylinder 1 is larger than the outer diameter of the displacement cylinder 2, and the displacement cylinder 2 can slide up and down inside the fixed cylinder 1; preferably, the bottom of the fixed cylinder 1 is slidably connected to the outside of the displacement cylinder 2 through a slider groove structure;

[0049] The inner wall of the fixed cylinder 1 is provided with one or more first transmission grooves 4, and the outer wall of the displacement cylinder 2 is provided with one or more drive grooves 3. The drive grooves 3 and the first transmission grooves 4 are arranged opposite to each other. Each drive groove 3 is equipped with a first rack 5, and each first transmission groove 4 is equipped with a first gear 13. When the first rack 5 moves upward, it meshes with the first gear 13. During the freezing process, under the action of tangential freezing force, the displacement cylinder 2 is lifted up and moves upward. The first rack 5 in the drive groove 3 on its outer wall also moves upward. When the first rack 5 moves to the position of contacting the first gear 13, since the first gear 13 and the first rack 5 can mesh, the first rack 5 drives the first gear 13 to start rotating.

[0050] The top of the first transmission groove 4 is fixed with a horizontally extending rod holder 6. The end opening of the rod holder 6 communicates with the opening 31 formed on the fixed cylinder 1. A fixed cone 7 is slidably connected inside the rod holder 6. Preferably, the fixed cone 7 is slidably connected inside the rod holder 6 through a slider groove structure. A second rack 11 is fixed on the side of the fixed cone 7. The first gear 13 is connected to the second rack 11 through a gear bevel gear reversing transmission assembly.

[0051] Preferably, the second rack 11 is slidably connected to a through groove 12 opened in the side wall of the rod holder 6; the opening of the through groove 12 allows space for the gear bevel gear reversing transmission assembly to mesh with the second rack 11. When frost heave occurs, the first rack 5 rises, and through the transmission of the gear bevel gear reversing transmission assembly, the second rack 11 is gradually pushed to move in a straight line along the trajectory of the through groove 12.

[0052] like Figures 7-8The front end of the fixed cone 7 is provided with a second transmission groove 20. The through rod 21 is slidably connected in the second transmission groove 20. The outer end of the through rod 21 passes through the end opening of the second transmission groove 20, and the inner end of the through rod 21 is connected in the second transmission groove 20 through a first spring 24. A second limiting block 23 is fixed on the side wall of the through rod 21. The second limiting block 23 passes through the clearance groove 30 opened on the fixed cone 7 and is slidably connected in the limiting groove 22 opened on the side wall of the rod holder 6. The side of the second limiting block 23 away from the through rod 21 extends out of the limiting groove 22 and is located outside the limiting groove 22.

[0053] One end of the through rod 21 extending outside the second transmission groove 20 is hinged with a plurality of reinforcing rods 25. Preferably, the plurality of reinforcing rods 25 are distributed in an umbrella shape. The portion of the through rod 21 located outside the second transmission groove 20 is fitted with a first collar 26. The first collar 26 is slidably engaged with the through rod 21. Each reinforcing rod 25 is fitted with a second collar 27 that is slidably engaged with it. Each second collar 27 is hinged with a support rod 28. The other end of the support rod 28 is hinged to the outside of the first collar 26.

[0054] The second transmission groove 20 is connected to the extended end of the fixed cone 7. A through rod 21 is slidably connected to the second transmission groove 20 via a slider and a sliding groove structure. A limit groove 22 is provided on the side wall of the rod holder 6. A first spring 24 is fixedly connected to the left end of the through rod 21 by bolts. The left end of the first spring 24 is fixedly connected to the side wall of the second transmission groove 20 by screws. When the fixed cone 7 slowly extends, and the extension reaches a certain distance, the second limit block 23 contacts the side wall of the limit groove 22, causing the through rod 21 to stop moving forward. The fixed cone 7 continues to move forward under the drive of the second rack 11. At this time, the first spring 24 will... When compressed and shortened, the relative displacement is such that the fixed cone 7 extends outward while the through rod 21 remains stationary. The front end of the fixed cone 7 presses against the first ring 26, causing it to slide outward along the through rod 21. This causes the reinforcing rod 25 to slide outward and break free from the constraint of the rod box 6. Several support rods 28 will unfold the several reinforcing rods 25 that were originally contracted and pressed against the through rod 21, thus expanding the reinforcing rods 25 while the fixed cone 7 slowly extends. Finally, the reinforcing rods 25, which are distributed in an umbrella shape, pass through the opening 31 on the fixed cylinder 1 and unfold, forming an anchor. This can strengthen the effect of the fixed cone 7 in limiting the vertical displacement of the fixed cylinder 1 and improve the overall stability of the structure when frost heave occurs.

[0055] Preferably, when the displacement cylinder 2 rises due to frost heave, the tangential vertical displacement of the displacement cylinder 2 caused by frost heave is converted into the horizontal displacement of the second rack 11 by the gear bevel gear reversing transmission assembly provided in the first transmission groove 4, as detailed below. Figure 4The diagram shows the meshing connection. The gear bevel gear reversing transmission assembly includes a second gear 14, a third gear 15, a fourth gear 16, a first bevel gear 17, a second bevel gear 18, and a fifth gear 19. The second gear 14 is rotatably connected to the side wall of the first transmission groove 4 via a bearing and rod assembly. The third gear 15 meshes with one side of the second gear 14. The third gear 15 and the first gear 13 are located on opposite sides of the second gear 14. The third gear 15 meshes with the fourth gear 16. The fourth gear 16 is coaxially welded to the first bevel gear 17, which is rotatably connected to the side wall of the first transmission groove 4. The tooth surface of the first bevel gear 17 meshes with the second bevel gear 18, which is arranged perpendicularly to the first bevel gear 17. The top of the second bevel gear 18 is welded to the fifth gear 19, which is rotatably connected to the top wall of the first transmission groove 4. The fifth gear 19 meshes with the second rack 11.

[0056] When the first gear 13 slowly rises and rotates due to engagement with the first rack 5, this rotation is effectively transmitted to the meshing second gear 14. As the second gear 14 rotates, it drives the third gear 15 to rotate as well. The rotation of the third gear 15 then drives the meshing fourth gear 16 to rotate, which directly translates into rotation of the first bevel gear 17. The tooth surfaces of the first bevel gear 17 and the second bevel gear 18 mesh with each other and are arranged perpendicularly. Therefore, when the first bevel gear 17 rotates, it drives the second bevel gear 18 to rotate horizontally. This change in rotation direction is achieved through the special tooth surface shape of the bevel gears, which ensures that torque is transmitted vertically while simultaneously achieving a 90-degree change in rotation direction. Finally, the rotation of the second bevel gear 18 is transmitted to the top fifth gear 19. The fifth gear 19 can rotate freely along with the rotation of the second bevel gear 18, thereby driving the second rack 11 to move horizontally.

[0057] Example 2

[0058] Because the displacement cylinder 2 and the fixed cylinder 1 need to be connected and installed together during the hoisting process, with the fixed cylinder 1 placed first and the displacement cylinder 2 sliding and hoisted within it, and considering that the first rack 5 may easily come into contact with the first gear 13 during this hoisting process, affecting the subsequent frost heave transmission, an adjustment component for adjusting the meshing state of the first rack 5 is designed at the bottom of the first rack 5.

[0059] Specifically, such as Figure 3 As shown, the adjustment assembly includes a connecting rod 8 welded to one side of the first rack 5. A first limiting block 9 is welded to the end of the connecting rod 8 away from the first rack 5. The first limiting block 9 is slidably connected to a slot formed in the side wall of the displacement cylinder 2. A plurality of second springs 10 are connected between the first rack 5 and the inner side wall of the drive groove 3.

[0060] The cross-sectional shape of the teeth of the first rack 5 is trapezoidal. The top surface of the teeth of the first rack 5 is a plane, and the bottom surface of the teeth of the first rack 5 is an inclined plane. Thus, the first rack 5 and the first gear 13 form a one-way meshing. After assembly, when the first rack 5 moves upward, the top plane of the teeth of the first rack 5 contacts the teeth of the first gear 13. The top plane of the teeth of the first rack 5 meshes with the teeth of the first gear 13, which can drive the first gear 13 to rotate. During the assembly process, when the displacement cylinder 2 slides down in the fixed cylinder 1, the first rack 5 moves downward. The bottom inclined plane of the teeth of the first rack 5 contacts the first gear 13, but no effective meshing occurs. The first gear 13 will apply pressure to the bottom inclined plane.

[0061] The elastic force and number of the second spring 10 are determined through preliminary experiments to ensure that the second spring 10 does not contract during the upward movement of the first rack 5, and that the first rack 5 effectively meshes with the first gear 13. When the first rack 5 is assembled and descends, the second spring 10 contracts under the pressure of the first gear 13.

[0062] The adjustment assembly ensures that when the displacement cylinder 2 slides down inside the fixed cylinder 1, the contact between the first rack 5 and the first gear 13 is elastic and controllable. Specifically, when the displacement cylinder 2 is hoisted into the fixed cylinder 1 and slides down along the slide rail, the first gear 13 applies pressure to the bottom inclined surface of the teeth of the first rack 5. Since the bottom of the first rack 5 is connected to the inside of the displacement cylinder 2 through the connecting rod 8 and the first limiting block 9, and the first rack 5 is also connected to the inner wall of the drive groove 3 through several second springs 10, this design allows the second springs 10 to undergo a certain elastic deformation when the first rack 5 is subjected to pressure. In the initial contact stage, the second springs 10 act as a buffer, absorbing part of the impact force and preventing excessive impact force between the first rack 5 and the first gear 13, thereby reducing possible damage or jamming. As the displacement cylinder 2 continues to slide down, the first rack 5 gradually returns to its original position under the elastic force of the second spring 10. During this process, due to the presence of the connecting rod 8 and the first limiting block 9, the first rack 5 is confined within the drive groove 3 and will not completely disengage from its track due to the elastic force of the second spring 10. When the displacement cylinder 2 slides down to the predetermined position, that is, when the first rack 5 and the first gear 13 are completely separated, the entire installation process is completed. At this time, the second spring 10 is in an uncompressed state, ready for subsequent frost heave transmission. The adjustment component can also flexibly cope with frost heave displacements of different sizes and directions.

[0063] Example 3

[0064] like Figure 9As shown, a construction method for a self-locking sleeve isolation structure for preventing frost pull-out of pile foundations in seasonally frozen soil areas is carried out based on the self-locking sleeve isolation structure for preventing frost pull-out of pile foundations in seasonally frozen soil areas described in Examples 1-3, including the following steps:

[0065] Step S1, Measurement and Layout for Pile Positioning: Based on the design drawings, the pile positions are precisely laid out to ensure accuracy. Simultaneously, the dimensions of the fixed cylinder 1 and the displacement cylinder 2 are accurately designed and manufactured according to the actual drawings. This step ensures the accuracy and efficiency of subsequent construction, avoids construction delays or quality problems caused by dimensional discrepancies, improves construction precision, reduces errors, and lays a solid foundation for subsequent construction.

[0066] Step S2, Drilling the fixed cylinder 1: After the layout is completed, dig drainage ditches around the construction area or at suitable locations. The direction of the drainage ditches should be consistent with the low-lying areas to ensure that rainwater can flow in smoothly. Lay gravel or sand at the bottom of the drainage ditches to increase water permeability and ensure that surface water cannot flow into the holes during drilling, thus affecting the drilling quality. Then, use a drilling machine with a drill bit of the same diameter as the fixed cylinder 1 to perform drilling operations. After drilling to the designed depth of the fixed cylinder 1, stop drilling to ensure that the fixed cylinder 1 can be accurately installed in the predetermined position, prevent surface water from affecting the drilling quality, and ensure the accuracy of the installation position of the fixed cylinder 1.

[0067] Step S3, hoisting and placing the fixed cylinder 1: hoist the fixed cylinder 1 into the borehole formed in step S2, and ensure that the top surface of the fixed cylinder 1 is not higher than the maximum seasonal frost depth, so as to ensure the stability and accuracy of the fixed cylinder 1 and provide support for subsequent construction.

[0068] Step S4, Drilling of Displacement Cylinder 2: The drilling rig is fitted with a drill bit of the same diameter as the displacement cylinder 2 to drill the displacement cylinder 2. Drilling is stopped after reaching the designed depth for fixing the displacement cylinder 2. This ensures that the displacement cylinder 2 can be accurately installed in the predetermined position, providing space for subsequent installation of the displacement cylinder 2 and ensuring the accuracy of the installation position. Drilling continues until the designed depth of pile foundation 29 is reached, and then drilling is stopped.

[0069] Step S5, Hole Cleaning: After step S4 is completed, hole cleaning is performed to remove the sediment from the bottom of the pile and ensure thorough cleaning.

[0070] Step S6, Hole Formation Inspection and Acceptance: Inspect and accept the quality of the formed holes to check whether the quality of the formed holes is qualified.

[0071] Step S7, hoisting and lowering displacement cylinder 2: hoist displacement cylinder 2 into the hole and ensure its position is accurate.

[0072] Step S8, pile construction: Fabricate a steel cage according to the design requirements, hoist the steel cage into the hole, then prepare a concrete grouting pipe, hoist the grouting pipe into the hole, before grouting, ensure that the bottom of the pile is clean, free of water and sediment, and then use the grouting pipe to pour concrete to complete the pile foundation 29 construction.

[0073] The above description is only a preferred embodiment of the present invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A working method for preventing pile frost heaving in a seasonally frozen ground area by using a self-locking casing isolation structure, characterized in that, The self-locking casing isolation structure for preventing pile foundation frost heaving in the seasonally frozen soil area comprises a hollow fixed cylinder and a displacement cylinder slidingly sleeved in the fixed cylinder, and the top surface of the fixed cylinder is located below the seasonally frozen soil layer; One or more first transmission grooves are arranged on the inner wall of the fixed cylinder, one or more driving grooves are arranged on the outer wall of the displacement cylinder, the driving grooves and the first transmission grooves are arranged in pairs, each first transmission groove is equipped with a first gear, and each driving groove is equipped with a first rack. A transversely extending rod setting box body is fixed to the top of the first transmission groove, the end opening of the rod setting box body is communicated with an opening formed in the fixed cylinder, a fixed cone is slidingly connected in the rod setting box body, a second rack is fixed to the side surface of the fixed cone, and the first gear is drivingly connected with the second rack through a gear umbrella wheel reversing transmission assembly. A second transmission groove is formed in the front end of the fixed cone, a through rod is slidingly connected in the second transmission groove, the outer end of the through rod is arranged to pass out of the end opening of the second transmission groove, the inner end of the through rod is connected to the second transmission groove through a first spring, a second limiting block is fixed to the side wall of the through rod, the second limiting block passes through an avoiding groove formed in the fixed cone and is slidingly connected in a limiting groove formed in the rod setting box body. A plurality of reinforcing rods are hinged to one end of the through rod extending out of the second transmission groove, a first sleeve is sleeved on the position of the through rod outside the second transmission groove, a second sleeve is sleeved on each reinforcing rod in sliding fit, the second sleeve is hinged with a support rod, and the other end of the support rod is hinged to the outside of the first sleeve. The working method comprises the following steps: When the pile foundation is constructed in the displacement cylinder, the displacement cylinder is pulled up under the action of tangential frost heaving force, the displacement cylinder is displaced upward, the first rack is also displaced upward, the first rack is engaged with the first gear, the first gear is driven to rotate, the first gear drives the second rack to move outward through the gear umbrella wheel reversing transmission assembly, then the second rack drives the fixed cone to move to the opening end of the rod setting box body, when the second limiting block contacts with the side wall of the limiting groove, the through rod stops moving forward, the fixed cone continues to move forward under the driving of the second rack, at this time, the first spring is compressed and shortened, the first sleeve is pushed out along the through rod under the pushing of the front end of the fixed cone, the reinforcing rods are pushed out of the constraint of the rod setting box body, the umbrella-shaped reinforcing rods pass out of the opening of the fixed cylinder and are unfolded, and anchoring is formed.

2. The method of claim 1, wherein, The bottom of the fixed cylinder is slidingly connected to the outside of the displacement cylinder through a sliding block and a sliding groove structure.

3. The method of claim 1, wherein, The second rack is slidingly connected in a through groove formed in the side wall of the rod setting box body.

4. The method of claim 1, wherein, The through rod is slidingly connected in the second transmission groove through a sliding block and a sliding groove structure.

5. The method of claim 1, wherein, The gear umbrella wheel reversing transmission assembly comprises a second gear, a third gear, a fourth gear, a first bevel gear, a second bevel gear and a fifth gear, the second gear is rotationally connected to the first transmission groove side wall through a bearing and a rod assembly, one side of the second gear is engaged with the third gear, the third gear and the first gear are respectively located on opposite sides of the second gear, the third gear is engaged with the fourth gear, the fourth gear is coaxially welded with the first bevel gear which is rotationally connected with the first transmission groove side wall, the tooth surface of the first bevel gear is engaged with the second bevel gear which is arranged perpendicularly to the first bevel gear, the top of the second bevel gear is welded with the fifth gear which is rotationally connected with the first transmission groove top wall, and the fifth gear is engaged with the second rack.

6. The method of claim 1, wherein, The bottom of the first rack is provided with an adjusting assembly, the adjusting assembly comprises a connecting rod welded on one side of the first rack, a first limiting block is welded on one end of the connecting rod away from the first rack, the first limiting block is slidingly connected in a slot formed in the side wall of the displacement cylinder body, and a plurality of second springs are connected between the first rack and the inner side wall of the driving groove. The cross section shape of the tooth of the first rack is trapezoidal, the top surface of the tooth of the first rack is a plane, and the bottom surface of the tooth of the first rack is an inclined surface.

7. The method of claim 1, wherein the step of operating the engine comprises operating the engine at a temperature of 2000C or greater. A plurality of reinforcing rods are hingedly connected to the end of the through rod in an umbrella shape.

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