Cast-in-situ bored pile protection structure in extra-strong frost heaving area and construction method

Abstract

The invention discloses an extra-strong frost heaving area cast-in-situ bored pile protection structure and a construction method.The extra-strong frost heaving area cast-in-situ bored pile protection structure comprises a forming cylinder body, a displacement cylinder body arranged on the outer side of the forming cylinder body in a sliding and sleeving mode and a fixed cylinder body arranged on the outer side of the forming cylinder body in a sleeving mode, and the fixed cylinder body is located above the displacement cylinder body; the fixed cylinder body is fixed below the seasonal frozen soil through a fixing assembly, and a clamping assembly is arranged between the forming cylinder body and the displacement cylinder body, so that when the forming cylinder body moves upwards to a preset position, the forming cylinder body and the displacement cylinder body are fixed together through the clamping assembly to limit the ascending displacement of the forming cylinder body; a slip ring is arranged at the top of the displacement barrel, a fixing ring with a conical structure is fixed to the bottom of the outer side of the fixing barrel, and the inner circumferential inclined face of the slip ring is in sliding fit with the outer circumferential inclined face of the fixing ring. By means of the displacement of frost heaving and thaw collapse of the formed cylinder, returning of the formed cylinder and application of acting force of anti-frost heaving displacement are achieved, and the generation of the frost heaving amount is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of civil engineering, and in particular to a bored cast-in-place pile protection structure for an extremely strong frost heave zone and a construction method thereof. Background Art

[0002] The extremely severe frost heave zone refers to an area where the volume expands significantly due to water migration and ice crystal formation during the freezing process, and the soil frost heave rate is usually greater than 12%. Due to the significant frost heave phenomenon, the extremely severe frost heave zone poses a great threat to bored cast-in-place pile foundations. Repeated strong freeze-thaw cycles can easily cause engineering diseases such as pile foundation uplift, tilting, and even fracture, seriously affecting the safety and durability of the project. Therefore, how to effectively prevent and control freeze-thaw instability has become the core task of bored cast-in-place pile disaster prevention and mitigation work in extremely severe frost heave zones, and is also a key topic in the research of freeze-thaw deformation prevention and control technology.

[0003] At present, the main prevention and control measures for pile foundation freeze-thaw deformation include casing isolation method, variable cross-section method, coarse particle replacement method and drainage / waterproofing method. However, these methods face many limitations in their practical application in extremely severe frost heave areas. For example, the coarse particle replacement method and drainage / waterproofing method rely on reasonable drainage channels, but extremely severe frost heave areas usually have abundant groundwater and poor drainage conditions, which makes these methods difficult to implement effectively; the casing isolation method has insufficient material durability, and the casing is easy to be pulled out or damaged as the service time increases, and the prevention and control effect is significantly reduced; although the variable cross-section method increases the anchoring force of the pile foundation, it cannot effectively reduce the tangential frost heave force, and the pile body may still break due to excessive frost heave force. In addition, traditional prevention and control measures mostly aim to prevent the pile foundation from deformation at all, and do not consider the problem of pile body freeze-thaw pull-out sufficiently, which makes it difficult to meet the complex engineering needs of extremely severe frost heave areas.

[0004] In view of the above challenges, it is urgent to propose a new bored cast-in-place pile protection structure and construction method suitable for extremely strong frost heave areas, taking into account the prevention and control of freeze-thaw deformation and the protection of the pile body structure, and reducing the difficulty of later maintenance and management in an integrated form. This new solution should fully consider the regional freeze-thaw characteristics, and by optimizing the structural design and construction process, it can not only effectively control the effect of frost heave force on the pile foundation, but also significantly improve the anti-freeze-thaw performance and long-term stability of the pile foundation, providing more reliable technical support for cold region projects. Summary of the invention

[0005] The purpose of the present invention is to provide a bored cast-in-place pile protection structure for a particularly strong frost heave zone in response to the technical defects existing in the prior art, which utilizes the pile-soil isolation structure and the displacement of frost heave and thaw settlement to achieve the purpose of preventing and controlling the frost pullout of the pile foundation and reducing the tangential frost heave force, thereby protecting the bored cast-in-place piles and reducing the risk of engineering diseases.

[0006] The technical solution adopted to achieve the purpose of the present invention is: A bored pile protection structure for a particularly strong frost heave zone comprises a forming cylinder, a displacement cylinder slidably sleeved on the outside of the forming cylinder, and a fixed cylinder sleeved on the outside of the forming cylinder, wherein the fixed cylinder is located above the displacement cylinder, and a fixing assembly is provided on the fixed cylinder to fix the fixed cylinder under seasonal frozen soil through the fixing assembly, wherein: A clamping assembly is provided between the forming cylinder and the displacement cylinder so that when the forming cylinder moves upward to a predetermined position, the forming cylinder and the displacement cylinder are fixed together through the clamping assembly to limit the upward displacement of the forming cylinder; A slip ring is provided on the top of the displacement cylinder, and a fixing ring with a conical structure is fixed on the outer bottom of the fixing cylinder. The inner circumferential inclined surface of the slip ring is slidably matched with the outer circumferential inclined surface of the fixing ring.

[0007] In the above technical solution, a plurality of convex teeth are fixedly connected to the inner circumferential inclined surface of the slip ring, and a plurality of grooves corresponding to the convex teeth are provided on the outer circumferential inclined surface of the fixed ring.

[0008] In the above technical solution, the convex tooth is a triangular structure with a flat surface on the side close to the slip ring and a hypotenuse on the side away from the slip ring.

[0009] In the above technical solution, one or more connecting grooves are provided on the inner side wall of the displacement cylinder, and a moving groove corresponding to the position of the connecting groove is provided on the outer side wall of the forming cylinder; The locking assembly comprises a limit block, a cross bar, an extension block, a first connecting rod, a second connecting rod, a third connecting rod and a clamping slot, wherein the cross bar is fixed in the connecting slot, preferably, one end or both ends of the cross bar are respectively welded to the two side walls of the connecting slot, an extension block is rotatably connected to the cross bar, a slot height of the movable slot is greater than a slot height of the connecting slot, a limit block is provided in the movable slot, and a three-link structure is provided on both sides of the limit block, the three-link structure comprises a first connecting rod, a second connecting rod and a third connecting rod, the top end of the third connecting rod is hinged to one end of the limit block, and the bottom end of the third connecting rod is hinged to the bottom of the movable slot, the top end of the first connecting rod is hinged to the other end of the limit block, and the bottom end of the first connecting rod is hinged to the extension block, the top end of the second connecting rod is hinged to the extension block, and the bottom end of the second connecting rod is hinged to the bottom of the movable slot; The clamping groove is arranged on the inner side wall of the displacement cylinder and is located above the connecting groove for the limiting block to be inserted.

[0010] In the above technical solution, the cross section of the limit block is a trapezoid in which the length of the top surface is greater than the length of the bottom surface, and the shape of the slot corresponds to the shape of the limit block.

[0011] In the above technical solution, the fixing assembly includes a reinforcement block detachably connected to the outer wall of the fixed cylinder, a grouting channel is opened above the reinforcement block, the grouting channel is connected to the hollow cavity of the reinforcement block, and a hollow shear block is also connected to the bottom of the reinforcement block. The reinforcement block and the shear block are both annular structures, and the hollow cavity of the reinforcement block is connected to the hollow cavity of the shear block.

[0012] In the above technical solution, the reinforcement block is connected to the top of the fixed cylinder through a buckle.

[0013] In the above technical solution, the bored pile protection structure in the extra-strong frost heave zone further includes an energy storage component, which provides auxiliary force for the settlement and return of the forming cylinder, and the energy storage component includes a positioning block, a first spring, an energy storage groove, a convex ring, a sliding ring, a first concave ring and a second concave ring; The inner wall of the displacement cylinder is also provided with a locking groove, and the locking groove is located below the connecting groove. A locking block is slidably connected in the locking groove. The locking block slides in the locking groove through a slider slide groove structure. A plurality of first springs are connected between the locking block and the locking groove. An energy storage groove corresponding to the position of the locking groove is also provided on the outer side of the forming cylinder. A convex ring is welded on the top of the energy storage groove. A sliding ring is also sleeved in the energy storage groove. The sliding ring can vertically slide relative to the energy storage groove. A first concave ring and a second concave ring are welded on one side of the locking block close to the energy storage groove. The second concave ring is located above the first concave ring. The outer edge of the first concave ring protrudes from the outer edge of the second concave ring, and the concave shape of the first concave ring corresponds to the shape of the bottom end of the sliding ring, and the concave shapes on the upper and lower sides of the second concave ring correspond to the shape of the convex ring.

[0014] Another object of the present invention is to provide a working method of the bored pile protection structure in the particularly strong frost heave zone. The specific technical scheme includes the following steps: during the construction process, the fixed cylinder is fixed below the seasonal frozen soil by a fixing assembly, the top of the forming cylinder passes through the fixed cylinder and is flush with the ground surface, the forming cylinder serves as a casting template for the upper part of the pile foundation, when the temperature drops and the soil around the pile frost heaves, the forming cylinder will be slowly lifted up under the action of the tangential frost heave force; since a displacement cylinder is fitted in the middle of the outer wall of the forming cylinder, the displacement cylinder can slide up and down relative to the forming cylinder until the clamping assembly between the forming cylinder and the displacement cylinder is fixed; After the engaging assembly between the forming cylinder and the displacement cylinder is fixed, the forming cylinder drives the displacement cylinder to rise slowly, and the continuously slowly rising displacement cylinder drives the slip ring to gradually approach the fixing ring. When the slip ring is fitted with the fixing ring, due to the presence of the fixing assembly on the fixing cylinder, the fixing cylinder is difficult to move up and down during frost heave, and has stronger pull-out strength. Therefore, the slip ring will continue to slide on the surface of the fixing ring, and the end of the slip ring will gradually expand as it slides, and the contact area between the slip ring and the side wall of the borehole will gradually increase, and the friction between the slip ring and the side wall of the borehole will also increase accordingly, further enhancing the connection force between the displacement cylinder and the side wall of the borehole, effectively offsetting the tangential frost heave force, slowing down the frost heave of the pile foundation to stop the rise of the pile foundation, and achieving the effect of enhancing the pile foundation's anti-frost heave displacement.

[0015] When the temperature rises in spring and the frozen soil melts, the upward tangential frost heave force on the forming cylinder slowly decreases, and the forming cylinder also slowly descends. The forming cylinder slides down relative to the displacement cylinder, and the engaging assembly disengages at the same time. Therefore, the forming cylinder slides down smoothly, and the displacement cylinder also falls back under the contraction of the slip ring.

[0016] Another object of the present invention is to provide a construction method for the bored pile protection structure in the particularly strong frost heave zone. The specific technical solution comprises the following steps: Step S1, excavation: after locating the position of the pile according to the drawing, excavation is performed according to the arrangement position and size of the reinforcement block and the shear block, and after the position and depth of the reinforcement block and the shear block are dug out, the reinforcement block and the shear block are placed; Step S2, drilling holes for the fixed cylinder: after the reinforcement blocks and the shear blocks are placed, a drill bit with the same radius as the fixed cylinder is selected to drill holes with the designed length of the fixed cylinder as the depth; Step S3, drilling a hole for the displacement cylinder: replacing a drill bit with the same radius as the displacement cylinder, and drilling a hole with a designed length of the displacement cylinder as a depth; Step S4, drilling holes for the forming cylinder and the pile foundation: replacing a drill bit with the same radius as the forming cylinder, and drilling holes with the designed depth of the pile foundation as the drilling depth; Step S5, hole quality inspection and acceptance: inspect and accept the quality of the hole to check whether the hole quality is qualified; Step S6, hanging and placing the cylinder: hanging and placing the forming cylinder, the displacement cylinder and the fixed cylinder into the hole in sequence; Step S7, pouring the pile foundation: making a steel cage according to the design requirements, hanging the steel cage into the forming cylinder, then preparing a concrete pouring pipe, hanging the pouring pipe into the forming cylinder, pouring concrete through the pouring pipe, and vibrating the poured concrete in sections during the process; Step S8, pouring reinforcement blocks: finally pouring concrete into the grouting channel to form reinforcement blocks and shear blocks; Step S9, pile foundation maintenance and acceptance: after pouring is completed, the pile foundation is maintained and the pile foundation acceptance is completed; Step S10, shallow backfill: backfill and compact the part above the reinforcement block.

[0017] Compared with the prior art, the present invention has the following beneficial effects: 1. The setting of the snap-fit ​​assembly allows the forming cylinder to rise a certain distance, and then increases the bonding force between the displacement cylinder and the soil as the forming cylinder continues to rise. In cold areas, pile foundations are often affected by tangential frost heave, which causes the pile foundation to have an upward displacement, namely the amount of frost heave. If the pile foundation is subjected to excessive frost heave force, it may crack due to its inability to adapt to this stress, thus affecting its stability and service life. The traditional design of pile foundations that are completely free of frost heave often fails to effectively reduce the frost heave force, but this design avoids this problem by allowing a certain relative displacement of the forming cylinder. When the forming cylinder rises due to frost heave, the snap-fit ​​assembly is used to achieve relative limitation between the displacement cylinder and the forming cylinder, thereby reducing the amount of frost heave, enhancing the stability of the structure during frost heave, and reducing the probability of structural damage; 2. The setting of the energy storage component realizes the efficient release of energy and provides a strong auxiliary force for the return of the forming cylinder. This mechanism can significantly reduce the impact of deep friction on the fall of the forming cylinder during the thawing process. As the frozen soil gradually melts, the physical properties of the soil change, and the deep friction tends to increase, which increases the difficulty of the forming cylinder falling. However, through the clever coordination of the energy storage component and the locking component, the system can provide additional power at critical moments to help the forming cylinder overcome the obstacles of deep friction and smoothly fall to the predetermined position; 3. The volume of frozen soil changes significantly during freezing and thawing, and this volume deformation will exert uneven lateral pressure on the pile body. Especially in seasonal frozen soil areas, this uneven lateral pressure will continue to accumulate as the freeze-thaw cycle continues, eventually causing the pile body to bend and deform. If the deformation is too large, it may even cause the pile body to break, seriously affecting the bearing capacity and service life of the pile foundation. By closely combining the fixing components with the soil, the overall stability of the pile foundation and the surrounding soil is enhanced, and the deformation resistance of the pile foundation is further improved, thereby effectively avoiding the risk of bending, deformation and fracture of the pile body. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is an overall axonometric diagram of the bored cast-in-place pile protection structure in the extra-strong frost heave zone of the present invention.

[0019] Figure 2 It is a front cross-sectional view of the bored cast-in-place pile protection structure in the particularly strong frost heave zone of the present invention.

[0020] Figure 3It is an axonometric cross-sectional view of the bored cast-in-place pile protection structure in the extra-strong frost heave zone of the present invention.

[0021] Figure 4 for Figure 2 An enlarged schematic diagram of point A in the middle, where (a) the limit block is not inserted into the slot, and (b) the limit block is inserted into the slot.

[0022] Figure 5 It is an axonometric schematic diagram of the engaging components in the bored cast-in-place pile protection structure in the extra-strong frost heave zone of the present invention.

[0023] Figure 6 for Figure 2 The enlarged schematic diagram of point B in the figure, where (a) is the initial state after the forming cylinder and the displacement cylinder are assembled, and (b) is the state when the forming cylinder begins to descend.

[0024] Figure 7 It is an axonometric schematic diagram of the energy storage component in the bored cast-in-place pile protection structure in the extra-strong frost heave zone of the present invention.

[0025] Figure 8 for Figure 2 Enlarged schematic diagram of point C in the middle.

[0026] Fig. 9 The present invention is a schematic diagram of the construction process of the bored cast-in-place pile protection structure in the extra-strong frost heave zone.

[0027] 1. Forming cylinder; 2. Fixed cylinder; 3. Displacement cylinder; 4. Fixed ring; 5. Slip ring; 6. Connection groove; 7. Moving groove; 8. Grouting channel; 9. Reinforcement block; 10. Shear block; 11. Limit block; 12. Cross bar; 1201. Extension block; 1202. First connecting rod; 1203. Second connecting rod; 1204. Third connecting rod; 13. Slot; 14. Positioning slot; 15. Positioning block; 16. First spring; 17. Energy storage slot; 18. Convex ring; 19. Sliding ring; 20. First concave ring; 21. Second concave ring; 22. Groove; 23. Convex tooth; 24. Pile foundation. DETAILED DESCRIPTION

[0028] The present invention is further described in detail below in conjunction with specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0029] Example 1 like Figure 1-Figure 8As shown, a bored cast-in-place pile protection structure in a particularly strong frost heave zone comprises a forming cylinder 1, a displacement cylinder 3 slidably sleeved on the outside of the forming cylinder 1, and a fixed cylinder 2 sleeved on the outside of the forming cylinder 1, wherein the fixed cylinder 2 is located above the displacement cylinder 3, and a fixing assembly is provided on the fixed cylinder 2, so as to fix the fixed cylinder 2 under seasonal frozen soil through the fixing assembly, wherein: A clamping assembly is provided between the forming cylinder 1 and the displacement cylinder 3 so that when the forming cylinder 1 moves upward to a predetermined position, the forming cylinder 1 and the displacement cylinder 3 are fixed together through the clamping assembly to limit the upward displacement of the forming cylinder 1; A slip ring 5 is provided on the top of the displacement cylinder 3 , and a fixing ring 4 with a conical structure is fixed (preferably welded) to the outer bottom of the fixing cylinder 2 , and the inner circumferential inclined surface of the slip ring 5 is slidably matched with the outer circumferential inclined surface of the fixing ring 4 .

[0030] During the construction process, the fixed cylinder 2 is fixed under the seasonal frozen soil through a fixing assembly, and the top of the forming cylinder 1 passes through the fixed cylinder 2, and the top of the forming cylinder 1 is flush with the ground surface. The forming cylinder 1 serves as a casting template for the upper part of the pile foundation 24, which can ensure the casting of shallow concrete and the forming of the pile foundation 24, and is convenient for structural construction. Taking a freeze-thaw cycle as an example to describe the structural design of this scheme, when the temperature drops and the soil around the pile produces frost heave, the forming cylinder 1 will be slowly lifted under the action of the tangential frost heave force; because the middle part of the outer wall of the forming cylinder 1 is fitted with a displacement cylinder 3, the displacement cylinder 3 can slide up and down relative to the forming cylinder 1 until the clamping assembly between the forming cylinder 1 and the displacement cylinder 3 is fixed. The setting of the clamping assembly not only allows the displacement cylinder 3 to have a certain upward displacement when it is affected by frost heave, but also ensures that this upward displacement is stable, avoiding excessive displacement or instability of the structure.

[0031] After the locking assembly between the forming cylinder 1 and the displacement cylinder 3 is fixed, the forming cylinder 1 drives the displacement cylinder 3 to rise slowly, and the displacement cylinder 3 that continues to rise slowly will drive the slip ring 5 to gradually approach the fixed ring 4. When the slip ring 5 is fitted with the fixed ring 4, due to the presence of the fixing assembly on the fixed cylinder 2, the fixed cylinder 2 is difficult to move up and down during frost heave, and has a stronger pull-out strength. Therefore, the slip ring 5 will continue to slide on the surface of the fixed ring 4, and the end of the slip ring 5 will gradually expand as it slides, forming a barb effect similar to that of the barb, piercing into the surrounding soil to form a locking effect, and the contact area between the slip ring 5 and the soil on the side wall of the borehole will gradually increase, and the friction between the slip ring 5 and the soil on the side wall of the borehole will also increase accordingly. The more the displacement cylinder 3 is pulled up, the greater the locking or anchoring force and the friction force will be, further enhancing the connection force between the displacement cylinder 3 and the soil on the side wall of the borehole, effectively offsetting the tangential frost heave force, slowing down the frost heave of the pile foundation 24 to stop the rise of the pile foundation 24, and achieving the effect of enhancing the pile foundation 24's anti-frost heave displacement.

[0032] When the temperature rises in spring and the frozen soil melts, the upward tangential frost heave force on the forming cylinder 1 slowly decreases, and the forming cylinder 1 also slowly descends under the action of the negative friction resistance of the thawing soil. The forming cylinder 1 slides down relative to the displacement cylinder 3, and the engaging assembly disengages. Therefore, the forming cylinder 1 will slide down smoothly, and the displacement cylinder 3 will also fall back under the contraction of the slip ring 5. Specifically, during the frost heave period, the inner circumferential inclined surface of the slip ring 5 will not completely detach from the outer circumferential inclined surface of the fixing ring 4 during the expansion process, so as to ensure that the slip ring 5 can shrink smoothly during the melting of the frozen soil.

[0033] Preferably, a plurality of convex teeth 23 are fixedly connected to the inner circumferential inclined surface of the slip ring 5, and a plurality of grooves 22 corresponding to the convex teeth 23 are provided on the outer circumferential inclined surface of the fixed ring 4. The convex teeth 23 are triangular structures with a plane on the side close to the slip ring 5 and a hypotenuse on the side away from the slip ring 5. When the slip ring 5 gradually slides and fits the fixed ring 4 following the displacement of the displacement cylinder 3, the plurality of convex teeth 23 will mesh with the plurality of grooves 22 in sequence, and together form a meshing mechanism that follows the rise of the displacement cylinder 3. This gradual meshing method not only ensures the tight connection between the slip ring 5 and the fixed ring 4, but also reduces the risk of falling off due to sudden impact or vibration. In addition, this design has significant advantages in long-term use. Since the meshing between the convex teeth 23 and the grooves 22 is gradual and continuous, the wear between the convex teeth 23 and the grooves 22 will be more uniform. Even after long-term use, the connection between the slip ring 5 and the fixed ring 4 will not fail due to local excessive wear.

[0034] Example 2 This embodiment further illustrates the structure of the engaging assembly.

[0035] like Figure 4As shown, the inner wall of the displacement cylinder 3 is provided with one or more connecting grooves 6, and the outer wall of the forming cylinder 1 is provided with moving grooves 7 corresponding to the positions of the connecting grooves 6, and one set of corresponding connecting grooves 6 and moving grooves 7 is taken as an example for description.

[0036] The engaging assembly includes a limit block 11, a cross bar 12, an extension block 1201, a first connecting rod 1202, a second connecting rod 1203, a third connecting rod 1204 and a card slot 13, wherein the cross bar 12 is fixed in the connecting slot 6, preferably, one end or both ends of the cross bar 12 are respectively welded to the side wall of the connecting slot 6, and the cross bar 12 is rotatably connected with the extension block 1201, preferably, the extension block 1201 is rotatably connected to the cross bar 12 through a bearing, the slot height of the movable slot 7 is greater than the slot height of the connecting slot 6, a limit block 11 is provided in the movable slot 7, and a three-link structure is provided on both sides of the limit block 11, and the three-link structure includes a first connecting rod 1202, a second connecting rod 1203, and a third connecting rod 1204. 1203 and a third connecting rod 1204, the top end of the third connecting rod 1204 is hinged to one end of the limit block 11, and the bottom end of the third connecting rod 1204 is hinged to the bottom of the movable groove 7, the top end of the first connecting rod 1202 is hinged to the other end of the limit block 11, and the bottom end of the first connecting rod 1202 is hinged to the extension block 1201, the top end of the second connecting rod 1203 is hinged to the extension block 1201, and the bottom end of the second connecting rod 1203 is hinged to the bottom of the movable groove 7, and further, a connecting shaft is provided at the end of the extension block 1201, and the bottom end of the first connecting rod 1202 and the top end of the second connecting rod 1203 are respectively hinged on the connecting shaft.

[0037] The locking groove 13 is formed on the inner wall of the displacement cylinder 3 and is located above the connecting groove 6 for the limiting block 11 to be inserted into.

[0038] In addition, in order to make the first connecting rod 1202 produce a pulling force, the top of the second connecting rod 1203 on both sides and the bottom of the first connecting rod 1202 are respectively hinged on the connecting shaft at the end of the extension block 1201, and the inner wall of the displacement cylinder 3 is also provided with a slot 13 located above the connecting groove 6. The position of the limit block 11 corresponds to the position of the slot 13. The slot 13 is located in the moving track of the limit block 11 and can fit with the limit block 11. When the forming cylinder 1 rises due to the frost heave effect, the second connecting rod 1203 and the third connecting rod 1204 will swing with the rise of the forming cylinder 1. In this process, due to the existence of the first connecting rod 1202, the swing displacement of the second connecting rod 1203 and the first connecting rod 1202 will swing with the axis of the cross bar 12 as the center of the circle, so that the limit block 11 gradually approaches the slot 13 along an arc track. Movement. When the limit block 11 is finally inserted into the slot 13 , relative limiting is achieved between the displacement cylinder 3 and the forming cylinder 1 , the relative displacement between the displacement cylinder 3 and the forming cylinder 1 is effectively controlled, and the displacement cylinder 3 will rise along with the rise of the forming cylinder 1 .

[0039] By setting the limit block 11, the upward displacement of the forming cylinder 1 can be controlled. On the one hand, it allows the forming cylinder 1 to have a certain upward displacement (frost heave amount) when subjected to frost heave, thereby avoiding damage to the pile foundation 24 caused by excessive frost pullout force; at the same time, due to the existence of the limit block 11 and the slot 13, this upward displacement is controllable and will not cause excessive displacement or instability of the pile foundation 24. On the other hand, in the thawing stage, the descent of the forming cylinder 1 will cause the limit block 11 to disengage from the slot 13, and the forming cylinder 1 can smoothly return to its original position.

[0040] Preferably, the cross section of the stopper 11 is a trapezoidal structural block with a top surface length greater than a bottom surface length, and the shape of the slot 13 corresponds to the shape of the stopper 11. After the forming cylinder 1 rises to the position where the stopper 11 is inserted into the slot 13, the displacement cylinder 3 can synchronously follow the forming cylinder 1 to rise. As a detachable connection point, the stopper 11 plays a vital role in the system. It mainly bears the tangential forces from the displacement cylinder 3 and the forming cylinder 1. These forces continue to act during the frost heave process, requiring the stopper 11 to have sufficient strength and stability. The trapezoidal structure design with a horizontal top surface and inclined sides of the stopper 11, on the one hand, the trapezoidal structure with a horizontal top surface can more effectively resist the downward cutting force, ensuring that in extreme cases, such as a sudden increase in load or external impact, the stopper 11 can still remain stable, enhance the overall rigidity and durability of the structure, and avoid failure of prevention and control. On the other hand, the inclined design of the side brings another significant advantage: it makes it easier for the stopper 11 to be inserted into the slot 13. The inclined side surface can guide the limit block 11 to gradually go deeper along the entrance of the slot 13 until it is completely fitted. This design not only simplifies the installation process and improves work efficiency, but also ensures a close fit between the limit block 11 and the slot 13, reducing potential risks caused by looseness or misalignment. In addition, due to the inclined design of the side surface, the limit block 11 can distribute stress more evenly when subjected to tangential force, reducing fatigue damage caused by stress concentration. This means that even under harsh working conditions, the limit block 11 can maintain its original mechanical properties, providing strong support for the stable operation of the pile foundation 24 system.

[0041] Example 3 This embodiment further illustrates the structure of the fixing assembly.

[0042] The fixing assembly includes a reinforcement block 9 which is detachably connected to the outer wall of the fixed cylinder 2. Preferably, the reinforcement block 9 is connected to the top of the fixed cylinder 2 by a snap buckle. A grouting channel 8 is opened above the reinforcement block 9. The grouting channel 8 is connected to the hollow cavity of the reinforcement block 9. A hollow shear block 10 is also connected to the bottom of the reinforcement block 9. The reinforcement block 9 and the shear block 10 are both annular structures. The top of the shear block 10 is welded to the bottom of the reinforcement block 9, and the hollow cavity of the reinforcement block 9 is connected to the hollow cavity of the shear block 10.

[0043] On the one hand, after the pile foundation 24 is poured, the reinforcement block 9 and the shear block 10 are poured through the grouting channel 8. The presence of the reinforcement block 9 further enhances the bearing capacity of the fixed cylinder 2, so that it can better resist the influence of the uneven horizontal frost heave force of the pile foundation 24. The main function of the shear block 10 is to enhance the stability of the structure in the horizontal direction, especially when the pile foundation 24 is subjected to the uneven horizontal frost heave force, it can effectively prevent the structure from tilting and failing due to the uneven horizontal frost heave force. On the other hand, even if a large tangential frost heave force is generated between the pile foundation 24 and the forming cylinder 1, due to the reinforcement design of the fixed cylinder 2 and the presence of the grouting reinforcement layer, these friction forces are not enough to make the fixed cylinder 2 rise. Therefore, this design not only improves the stability of the pile foundation 24 under frost heave conditions, but also ensures the reliability and durability of the entire structural system in extreme environments.

[0044] Concrete and other materials are poured into the grouting channel 8, which will further fill and solidify the reinforcement block 9 and the shear block 10. The reinforcement block 9 is hollow and fixed to the outer wall of the fixed cylinder 2. Its existence can enhance the structural strength of the fixed cylinder 2. The hollow, annular shear block 10 can significantly improve the stability of the overall structure in the shear direction, especially when the pile foundation 24 is subjected to horizontal frost heave force. The combination of the reinforcement block 9 and the shear block 10 can effectively prevent the structure from tilting, thereby ensuring the stability and durability of the entire prevention and control structure.

[0045] Example 4 In order to reduce the risk of the deep frictional resistance affecting the falling of the forming cylinder 1 during the melting and sinking process, an energy storage component is provided in this embodiment, and the energy storage component provides auxiliary force for the sinking and returning of the forming cylinder 1. The energy storage component includes a positioning block 15, a first spring 16, an energy storage groove 17, a convex ring 18, a sliding ring 19, a first concave ring 20 and a second concave ring 21. Specifically: The inner wall of the displacement cylinder 3 is also provided with a locking groove 14, and the locking groove 14 is located below the connecting groove 6. A locking block 15 is slidably connected in the locking groove 14. Preferably, two locking blocks 15 are provided, and each locking block 15 slides in the locking groove 14 through a slider slide groove structure. A plurality of first springs 16 are connected between the locking block 15 and the locking groove 14. Preferably, the two ends of the first spring 16 are respectively welded to the corresponding locking block 15 and the inner wall of the locking groove 14. The outer side of the forming cylinder 1 is also provided with an energy storage groove 17 corresponding to the position of the locking groove 14, and a convex ring 18 is welded on the top of the energy storage groove 17. A sliding ring 19 is also sleeved in the energy storage groove 17, and the sliding ring 19 can slide vertically relative to the energy storage groove 17 In coordination, the first concave ring 20 and the second concave ring 21 are welded on one side of the positioning block 15 close to the energy storage groove 17. The second concave ring 21 is located above the first concave ring 20, and the outer edge of the first concave ring 20 protrudes from the outer edge of the second concave ring 21. The concave shape of the first concave ring 20 corresponds to the shape of the bottom end of the sliding ring 19, and the concave shapes on the upper and lower sides of the second concave ring 21 correspond to the shape of the convex ring 18, so that the convex ring 18 can push the second concave ring 21 when the forming cylinder 1 moves up and down to the position against the second concave ring 21. The positioning block 15 is displaced in the direction away from the convex ring 18 by the interaction force between the second concave ring 21 and the convex ring 18, and the first spring 16 is compressed so that the convex ring 18 can pass over the second concave ring 21 up and down.

[0046] The initial state after the forming cylinder 1 and the displacement cylinder 3 are assembled is as follows: Figure 6 As shown in (a), the convex ring 18 is located below the second concave ring 21, and the edge of the first concave ring 20 abuts against the outer wall of the sliding ring 19. When the forming cylinder 1 rises, the convex ring 18 passes over the second concave ring 21 upward, and the sliding ring 19 moves upward until it exceeds the first concave ring 20. Figure 6As shown in (b), when the forming cylinder 1 begins to descend, the sliding ring 19 also descends, and the sliding ring 19 passes through the second concave ring 21 and the first concave ring 20 in sequence. Since the outer edge of the first concave ring 20 protrudes from the outer edge of the second concave ring 21, the sliding ring 19 can easily pass through the second concave ring 21, but when it encounters the first concave ring 20, it will be limited by it and maintain the same horizontal plane with the first concave ring 20 and remain relatively still. When the convex ring 18 reaches the position of the second concave ring 21 and contacts the second concave ring 21, the positioning block 15 is displaced in the direction away from the convex ring 18 by the interaction force between the second concave ring 21 and the convex ring 18. This change causes the first concave ring 20 to also displace synchronously, thereby losing the limiting effect on the sliding ring 19. At this time, under the action of its own gravity, the sliding ring 19 falls rapidly and hits the inner bottom wall of the energy storage groove 17, realizing efficient energy release, providing auxiliary force for the return of the forming cylinder 1, ensuring the stable fall and return of the forming cylinder 1, and reducing the amount of frozen pull. In the process of melting and sinking, the risk of the deep frictional resistance affecting the fall of the forming cylinder 1 can be reduced. The energy storage component can adapt to different melting and sinking speeds and displacements, thereby improving the adaptability and stability of the entire prevention and control structure.

[0047] Example 5 As attached Fig. 9 As shown, a method for constructing a bored cast-in-place pile protection structure in an extremely strong frost heave zone is constructed based on the bored cast-in-place pile protection structure in an extremely strong frost heave zone described in any one of Examples 1-3, comprising the following steps: Step S1, excavation: after locating the position of the pile according to the drawing, excavation is performed according to the arrangement position and size of the reinforcement block 9 and the shear block 10, and after the position and depth of the reinforcement block 9 and the shear block 10 are dug out, the reinforcement block 9 and the shear block 10 are placed; Step S2, drilling holes for the fixed cylinder 2: after the reinforcement block 9 and the shear block 10 are placed, a drill bit with the same radius as the fixed cylinder 2 is selected, and a hole is drilled with the designed length of the fixed cylinder 2 as the depth; Step S3, drilling a hole for the displacement cylinder 3: replacing a drill bit with the same radius as the displacement cylinder 3, and drilling a hole with a designed length of the displacement cylinder 3 as a depth; Step S4, drilling holes for the forming cylinder 1 and the pile foundation 24: replace the drill bit with the same radius as the forming cylinder 1, and drill holes with the designed depth of the pile foundation 24 as the drilling depth; Step S5, hole quality inspection and acceptance: inspect and accept the quality of the hole to check whether the hole quality is qualified; Step S6, hanging and placing the cylinders: hanging and placing the forming cylinder 1, the displacement cylinder 3 and the fixed cylinder 2 into the hole in sequence; Step S7, pouring the pile foundation 24: making a steel cage according to the design requirements, hanging the steel cage into the forming cylinder 1, and then preparing a concrete pouring pipe, hanging the pouring pipe into the forming cylinder 1, pouring concrete through the pouring pipe, and vibrating the poured concrete in sections during the process; Step S8, reinforcement block pouring: finally pouring concrete into the grouting channel 8 to cast the reinforcement block 9 and the shear block 10 into shape; Step S9, maintenance and acceptance of the pile foundation 24: after pouring, the pile foundation 24 is maintained and the acceptance of the pile foundation 24 is completed; Step S10, shallow backfill: backfill and compact the portion above the reinforcement block 9.

[0048] The above is only a preferred embodiment of the present invention. It should be pointed out that, for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A bored pile protection structure for extremely strong frost heave areas, characterized in that: It includes a forming cylinder, a displacement cylinder slidably sleeved on the outside of the forming cylinder, and a fixed cylinder sleeved on the outside of the forming cylinder, wherein the fixed cylinder is located above the displacement cylinder, and a fixing assembly is provided on the fixed cylinder to fix the fixed cylinder below the seasonal frozen soil through the fixing assembly, wherein: A clamping assembly is provided between the forming cylinder and the displacement cylinder so that when the forming cylinder moves upward to a predetermined position, the forming cylinder and the displacement cylinder are fixed together through the clamping assembly to limit the upward displacement of the forming cylinder; A slip ring is provided on the top of the displacement cylinder, and a fixing ring with a conical structure is fixed on the outer bottom of the fixing cylinder. The inner circumferential inclined surface of the slip ring is slidably matched with the outer circumferential inclined surface of the fixing ring.

2. The protective structure for bored piles in extremely strong frost heave areas according to claim 1, characterized in that: A plurality of convex teeth are fixedly connected to the inner circumferential inclined surface of the slip ring, and a plurality of grooves corresponding to the convex teeth are provided on the outer circumferential inclined surface of the fixed ring.

3. The protective structure for bored piles in extremely strong frost heave areas according to claim 2, characterized in that: The convex teeth are triangular structures with a flat surface on one side close to the slip ring and a hypotenuse on the other side away from the slip ring.

4. The protective structure for bored piles in extremely strong frost heave areas according to claim 1, characterized in that: The inner wall of the displacement cylinder is provided with one or more connecting grooves, and the outer wall of the forming cylinder is provided with a moving groove corresponding to the position of the connecting grooves; The engaging assembly comprises a limit block, a cross bar, an extension block, a first connecting rod, a second connecting rod, a third connecting rod and a card slot, wherein the cross bar is fixed in the connecting slot, an extension block is rotatably connected to the cross bar, a slot height of the movable slot is greater than a slot height of the connecting slot, a limit block is arranged in the movable slot, and a three-link structure is arranged on both sides of the limit block, the three-link structure comprises a first connecting rod, a second connecting rod and a third connecting rod, the top end of the third connecting rod is hinged to one end of the limit block, and the bottom end of the third connecting rod is hinged to the bottom of the movable slot, the top end of the first connecting rod is hinged to the other end of the limit block, and the bottom end of the first connecting rod is hinged to the extension block, the top end of the second connecting rod is hinged to the extension block, and the bottom end of the second connecting rod is hinged to the bottom of the movable slot; The clamping groove is arranged on the inner side wall of the displacement cylinder and is located above the connecting groove for the limiting block to be inserted.

5. The protective structure for bored piles in extremely strong frost heave areas as claimed in claim 4, characterized in that: The cross section of the limit block is a trapezoid in which the length of the top surface is greater than the length of the bottom surface, and the shape of the slot corresponds to the shape of the limit block.

6. The protective structure for bored piles in extremely strong frost heave areas according to claim 4, characterized in that: The fixing assembly comprises a reinforcing block detachably connected to the outer side wall of the fixing cylinder, a grouting channel is provided above the reinforcing block, and the grouting channel is communicated with the hollow cavity of the reinforcing block.

7. The protective structure for bored piles in extremely strong frost heave areas according to claim 6, characterized in that: The bottom of the reinforcement block is also connected to a hollow shear block. Both the reinforcement block and the shear block are annular structures. The hollow cavity of the reinforcement block is communicated with the hollow cavity of the shear block.

8. The protective structure for bored piles in extremely strong frost heave areas according to claim 6, characterized in that: The reinforcement block is connected to the top of the fixed cylinder through a buckle.

9. The protective structure for bored piles in extremely strong frost heave areas according to claim 1, characterized in that: It also includes an energy storage component, which provides auxiliary force for the sinking and returning of the forming cylinder, and the energy storage component includes a positioning block, a first spring, an energy storage groove, a convex ring, a sliding ring, a first concave ring and a second concave ring; The inner wall of the displacement cylinder is also provided with a locking groove, and the locking groove is located below the connecting groove. A locking block is slidably connected in the locking groove. The locking block slides in the locking groove through a slider slide groove structure. A plurality of first springs are connected between the locking block and the locking groove. An energy storage groove corresponding to the position of the locking groove is also provided on the outer side of the forming cylinder. A convex ring is welded on the top of the energy storage groove. A sliding ring is also sleeved in the energy storage groove. The sliding ring can vertically slide relative to the energy storage groove. A first concave ring and a second concave ring are welded on one side of the locking block close to the energy storage groove. The second concave ring is located above the first concave ring. The outer edge of the first concave ring protrudes from the outer edge of the second concave ring, and the concave shape of the first concave ring corresponds to the shape of the bottom end of the sliding ring, and the concave shapes on the upper and lower sides of the second concave ring correspond to the shape of the convex ring.

10. The construction method of the bored pile protection structure in the super strong frost heave zone according to claim 1, characterized in that: The following steps are involved: Step S1, excavation of reinforcement blocks: after locating the position of the pile according to the drawing, excavation is performed according to the arrangement position and size of the reinforcement blocks and shear blocks, and after the position and depth of the reinforcement blocks and shear blocks are dug out, the reinforcement blocks and shear blocks are placed; Step S2, drilling holes for the fixed cylinder: after the reinforcement blocks and the shear blocks are placed, a drill bit with the same radius as the fixed cylinder is selected to drill holes with the designed length of the fixed cylinder as the depth; Step S3, drilling a hole for the displacement cylinder: replacing a drill bit with the same radius as the displacement cylinder, and drilling a hole with a designed length of the displacement cylinder as a depth; Step S4, drilling holes for the forming cylinder and the pile foundation: replacing a drill bit with the same radius as the forming cylinder, and drilling holes with the designed depth of the pile foundation as the drilling depth; Step S5, hole quality inspection and acceptance: inspect and accept the quality of the hole to check whether the hole quality is qualified; Step S6, hanging and placing the cylinder: hanging and placing the forming cylinder, the displacement cylinder and the fixed cylinder into the hole in sequence; Step S7, pouring the pile foundation: making a steel cage according to the design requirements, hanging the steel cage into the forming cylinder, then preparing a concrete pouring pipe, hanging the pouring pipe into the forming cylinder, pouring concrete through the pouring pipe, and vibrating the poured concrete in sections during the process; Step S8, pouring reinforcement blocks: finally pouring concrete into the grouting channel to form reinforcement blocks and shear blocks; Step S9, pile foundation maintenance and acceptance: after pouring is completed, the pile foundation is maintained and the pile foundation acceptance is completed; Step S10, shallow backfill: backfill and compact the part above the reinforcement block.

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