Cold region pile foundation freeze injury protection method

Abstract

The invention provides a cold region pile foundation freeze injury protection method which comprises the following steps: stacking a plurality of self-expanding fillers in a pit slot in which a pile foundation is arranged, and covering the pit slot with a soil body after the self-expanding fillers are stacked; each self-expansion filler comprises a flexible fabric bag and a soil body in the bag, the flexible fabric bag is filled with the soil body in the bag, each self-expansion filler comprises a flexible section and a self-expansion section, the placing directions of every two adjacent self-expansion fillers are opposite during filling, water absorption mechanisms are arranged on the inner side and the outer side of each self-expansion section respectively, and a plastic plate is arranged on the inner side of each self-expansion section. When the soil body is frozen, the soil body in the self-expansion filler expands, under the constraint effect of the flexible fabric bag, the expansion has a limit and is mainly subjected to horizontal expansion, under the guidance of the inner side plastic plate, the two self-expansion sections move towards the two sides respectively, and the contact effect between the self-expansion sections and the pile foundation is enhanced. On the premise that side friction resistance is not reduced, inhibition of the pile foundation freezing pulling phenomenon is achieved, and the influence of the extreme environment on the pile foundation operation stability is reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of cold region pile foundation frost damage protection, and relates to a cold region pile foundation frost damage protection method, in particular to a method of using a self-expanding filler to weaken the pile foundation frost pullout phenomenon. Background Art

[0002] Frost heave is one of the main diseases faced by cold region engineering. Pile foundations in frozen soil areas often suffer from frost heave instability or damage under multiple freeze-thaw cycles. The frost heave of pile foundations is mainly caused by the tangential frost heave force generated by the soil frost heave deformation being constrained by the pile foundation. When the tangential frost heave force exceeds the sum of the pile foundation's deadweight, upper load and maximum anchoring force, frost heave occurs. With the vigorous development of the Northeast and Northwest regions, the number of accidents and economic property losses caused by pile foundation frost heave are increasing day by day. Therefore, it is of great practical engineering significance to propose a pile foundation structure that can effectively inhibit or even eliminate the frost heave phenomenon.

[0003] The existing solutions for preventing and controlling the freezing and pulling out of pile foundations generally involve structural improvements to the pile foundations. Patents with publication numbers CN114703907A, CN114319463A, and CN116290134A all propose an improved pile foundation that uses solar panels, tarpaulin layers, or rubber sheets to reduce the frictional resistance of the pile-soil side in the freezing and pulling out area, so as to suppress the freezing and pulling out of the pile body. However, the technical solutions of the above patents generally have the problems of being unable to give full play to the bearing capacity of the pile foundation and the easy damage of the additional structure in a low temperature environment. As a common geotechnical material, flexible fabric has a good inhibitory effect on the freezing and thawing phenomenon. Patent publication number CN220364938U proposes a flexible fabric slope protection structure in a seasonally frozen area, which uses phase change materials to enhance the insulation effect of the flexible fabric and effectively suppress the freezing and thawing phenomenon. However, its application scenarios are relatively limited, and there are no reports on its direct use to suppress the freezing and pulling out of pile bodies. Therefore, giving full play to the advantages of flexible fabrics in frozen soil areas to suppress the freezing pullout of pile foundations has extremely strong engineering application value. Summary of the invention

[0004] In view of the problems existing in the prior art, the present invention provides a method for protecting pile foundations from freezing damage in cold regions, which can avoid the occurrence of freezing pullout and reduce the impact of freezing pullout on pile foundations.

[0005] To achieve the above object, the present invention adopts the following technical solutions: The invention provides a method for protecting pile foundations from freezing damage in cold regions. The method comprises the following steps: arranging a plurality of self-expanding fillers in a pit where the pile foundation is arranged; the self-expanding fillers comprise a flexible fabric bag and soil in the bag, wherein the soil in the bag is filled in the flexible fabric bag; the self-expanding filler is in a Y shape, comprising a flexible section and two bifurcated self-expanding sections, wherein the flexible section and the two self-expanding sections are integrally arranged; the plurality of self-expanding fillers are stacked in the pit, and two adjacent self-expanding fillers are placed in opposite directions; in a non-frozen state, the self-expanding fillers are in close contact with the pile foundation, and in a frozen state, the soil in the self-expanding filler expands, thereby enhancing the contact effect with the pile foundation and preventing the pile foundation from freezing.

[0006] Furthermore, plastic plates are respectively arranged on the inner sides of the two self-expanding sections of the self-expanding filler, and the plastic plates of the two self-expanding sections are connected as a whole; the plastic plates are fixedly connected to the flexible fabric bag wall; after the soil is frozen, the soil in the bag expands, and under the guidance of the plastic plates, the two self-expanding sections move to both sides respectively, and the angle between the two self-expanding sections becomes larger.

[0007] Furthermore, an inner water absorption mechanism is arranged on the inner side of the self-expanding section; the inner water absorption mechanism comprises an elastic water-permeable coating, a plurality of water-absorbing and swelling particles and a plurality of water-conducting fibers; the elastic water-permeable coating is arranged on the inner side of the plastic plate, and there is an interlayer between the elastic water-permeable coating and the plastic plate, and the water-absorbing and swelling particles are filled inside the interlayer; the water-absorbing and swelling particles expand when absorbing water and shrink when losing water; the two ends of the water-conducting fibers are respectively in contact with the soil in the bag and the water-absorbing and swelling particles.

[0008] Furthermore, the water-swellable particles are of a polyhedral spherical structure, and each face is in the shape of a triangle; the water-swellable particles include a central body and a plurality of triangular frames, the central body is a spherical water-swellable rubber, each triangular frame is fixed on the surface of the central body, two adjacent triangular frames share one edge, and the side length of the triangular frame increases / decreases with the expansion / contraction of the central body; each edge of the triangular frame includes a moving edge and two fixed edges of the same specification, the fixed edges and the moving edges are distributed up and down, and the fixed edges are slidably connected to the moving edges; the fixed edges are connected to the central body, and when the central body absorbs water and expands, the central body drives the two fixed edges to move away from each other along the moving edge; when the central body loses water and shrinks, the central body drives the two fixed edges to move toward each other along the moving edge.

[0009] Furthermore, the fixed edge is provided with a single-ball slider, and correspondingly, the moving edge is provided with a guide rail whose shape and size are mutually compatible with the single-ball slider; both the guide rail and the single-ball slider are magnetic, and the two are in a state of like poles repelling each other, and the single-ball slider is in a magnetic suspension state in the guide rail.

[0010] Furthermore, the plastic plate comprises a perforated plastic water-permeable plate and a water-permeable membrane; the inner side of the perforated plastic water-permeable plate is in contact with the water-absorbing and swelling particles, and the water-permeable membrane is arranged on the outer side of the perforated plastic water-permeable plate.

[0011] Furthermore, an outer water absorption mechanism is arranged on the outer side of the self-expanding section; the outer water absorption mechanism comprises a plurality of water-absorbing rubber monomers with a hexagonal cross-section, and the plurality of water-absorbing rubber monomers are connected to form a honeycomb structure, one side of the honeycomb structure is fixedly connected to the inner wall of the flexible fabric bag, and the other side is in contact with the soil in the bag; a central drainage pipe is arranged at the connection node of three adjacent water-absorbing rubber monomers, and the two ends of the central drainage pipe are respectively connected to the soil in the bag and the inner wall of the flexible fabric bag; a honeycomb outer wall is fixed outside the water-absorbing rubber monomer, and the honeycomb outer wall is a prestressed structure, and the water-absorbing rubber monomer is in a contracted state when not absorbing water.

[0012] Furthermore, the longitudinal section of the water-absorbing rubber monomer is a pentagon formed by combining a rectangle and a triangle up and down, and the convex part of the vertex of the bottom triangle is connected to the soil in the bag.

[0013] Furthermore, the method also includes: opening at least one group of collecting grooves outside the pit, arranging a hollow heat transfer pipe inside the collecting groove, and arranging a hose between the heat transfer pipe and the pit, connecting the heat transfer pipe and the pit through the hose.

[0014] Furthermore, the pit is a single-layer pit or a multi-step pit. When the pit is a multi-step pit, the self-expanding filler is placed from bottom to top. After the self-expanding filler is placed at each step, the step is leveled, and after leveling, the next step operation is continued.

[0015] Furthermore, after the self-expanding filler is placed in the pit, the original soil is used to cover the self-expanding filler to form a covering layer.

[0016] Beneficial effects of the present invention:

[0017] (1) The frost damage protection method for pile foundations in cold regions of the present invention gives full play to the excellent bearing characteristics of the pile foundation and the excellent restraint characteristics and thermal insulation characteristics of the self-expanding filler, raises the freezing front, reduces the freezing and thawing range around the pile, and achieves the weakening of the freezing and pulling phenomenon of the pile foundation. Compared with the traditional protection method, this protection method has the advantages of simple structure, stable operation, and easy availability of materials. It achieves the suppression of the freezing and pulling phenomenon without reducing the side friction resistance, improves the bearing capacity of the pile foundation, reduces the impact of extreme environment on the operation stability of the pile foundation, reduces the construction restrictions, and expands the scope of application.

[0018] (2) The present invention constrains the soil and water absorption structure inside the flexible fabric bag in the frost heave state through the good restraining performance of the self-expanding filler itself. At the same time, the distribution of the self-expanding segment in the self-expanding filler avoids the influence of uneven expansion on the structural strength of the self-expanding filler, thereby avoiding the occurrence of uneven expansion to a certain extent, achieving an increase in the contact stress of the pile-fabric interface, increasing the friction resistance on the pile side, and thus achieving the suppression of the frost pullout phenomenon of the pile foundation.

[0019] (3) The self-expanding section of the self-expanding filler in the present invention is provided with an inner water absorption mechanism and an outer water absorption mechanism, which can absorb the moisture in the soil inside the self-expanding filler, the pile-fabric interface and the fabric-soil interface, induce the migration of the moisture, and rely on the Y-shaped structure of the self-expanding filler to increase the contact area between the self-expanding filler and the pile and soil, accelerate the induced migration rate, achieve a range reduction in the moisture content of the soil, and avoid the occurrence of the pile foundation freeze-pull phenomenon.

[0020] (4) The water-swellable particles of the present invention innovatively introduce a magnetic suspension structure, which makes use of the tension changes of the water-swellable particles at different stages and the restraining force of the elastic water-permeable coating to achieve free expansion and contraction of the water-swellable particles, effectively avoiding the occurrence of lubricant condensation and blockage at the joints of the traditional expansion structure under low temperature conditions, ensuring that the water-swellable particles can still operate normally under the critical freezing temperature of the water body, effectively extending the service life of the structure, and indirectly ensuring the barrier effect of the migration of water from the soil to the pile, thereby achieving long-term suppression of the freeze-pull phenomenon of the pile foundation.

[0021] (5) The present invention is provided with a collecting trough, a heat transfer pipe and a hose, which can realize the collection of water in the pit, ensure that there is no water accumulation in the pit under seasonal melt water and heavy rainfall conditions, ensure the pit is dry, avoid the continuous expansion of the self-expanding section, avoid the phenomenon of long-term immersion of the self-expanding filler, effectively extend the service life of the self-expanding filler, ensure the multi-cycle operation of the internal self-expanding section, and thus ensure the long-term protection of the pile foundation in cold areas. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a schematic diagram of the pile foundation anti-freezing and pulling structure; Figure 2 Schematic diagrams of pile-fabric contact interface state and fabric-soil contact interface state; A is a schematic diagram of pile-fabric contact interface state, and B is a schematic diagram of fabric-soil contact interface state; Figure 3 Schematic diagrams of the cross-section of the self-expanding filler structure in multiple states; A is a schematic diagram of the cross-section of the self-expanding filler structure in the state of not filling the soil, B is a schematic diagram of the cross-section of the self-expanding filler structure in the state of filling the soil, and C is a schematic diagram of the cross-section of the self-expanding filler structure in the frozen state; Figure 4 Schematic diagram of the outer water absorption mechanism of the self-expanding section of the self-expanding filler; A is a schematic diagram of the connection between the outer water absorption mechanism and the flexible fabric bag, B is a schematic diagram of the outer water absorption mechanism in the water absorption state, and C is a schematic diagram of the outer water absorption mechanism in the non-water absorption state; Figure 5 Schematic diagram of the inner water absorption mechanism of the self-expanding section of the self-expanding filler; A is a schematic diagram of the inner and outer connections of the inner water absorption mechanism, B is a schematic diagram of the water absorption and expansion particles, C is a schematic diagram of the connection between the inner water absorption mechanism and the plastic plate, and D is a schematic diagram of the connection between the inner water absorption mechanism and the soil in the bag; Figure 6 Schematic diagram of the triangular framework of water-swelling particles; wherein A is a schematic diagram of the overall structure of the triangular framework of water-swelling particles, B is a schematic diagram of the corner structure of the triangular framework of water-swelling particles, C is a schematic diagram of the triangular framework of water-swelling particles after water absorption, and D is a schematic diagram of the connection structure of the fixed edge and the moving edge; Figure 7 Schematic diagram of the distribution of manifolds and hoses; A is a schematic diagram of the distribution of pile foundations, pits and manifolds, B is a schematic diagram of the connection between hoses and pits, C is a schematic diagram of the connection between hoses and heat transfer pipes, and D is a schematic diagram of the surface part of the heat transfer pipes; The symbols in the accompanying drawings are: 1. Soil outside the bag; 11. Original ground surface; 12. Ground surface after freezing without self-expanding filler; 13. Ground surface after freezing with self-expanding filler; 14. Overburden; 15. Soil inside the bag; 16. Pit; 2. Pile foundation; 3. Self-expanding filler; 31. Flexible section; 311. Flexible fabric bag wall; 32. Self-expanding section; 321. External water absorption mechanism; 322. Internal water absorption mechanism; 3211. Water-absorbing rubber monomer; 3212. Honeycomb outer wall; 32 13. Central drain pipe; 3214. Cavity body; 3221. Elastic water-permeable covering membrane; 32211. Water-conducting fiber; 3222. Water-absorbing and expanding particles; 32221. Fixed edge; 32222. Moving edge; 32223. Guide rail; 32224. Single-bead slider; 3223. Plastic plate; 32231. Plastic water-permeable plate with holes; 32232. Water-permeable membrane; 4. Collecting trough; 41. Hose; 42. Heat transfer tube; m. Freezing front; n. Seasonal freezing depth. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in combination with the embodiments of the present invention and the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0024] The present invention is used for the frost damage protection method of pile foundations in cold regions, which gives full play to the volume expansion characteristics of the self-expanding filler in a high humidity environment, enhances the interaction between the self-expanding filler and the pile body, effectively suppresses the freezing and pulling phenomenon of the pile body without reducing the side friction resistance of the pile body, and reduces the influence of extreme environment on the operation stability of the pile foundation. At the same time, with the help of the thermal insulation characteristics of the self-expanding filler, the temperature change of the soil around the pile is weakened, and the freezing front is lifted, so as to further suppress the freezing and pulling phenomenon of the pile foundation.

[0025] Example 1

[0026] The embodiment of the present invention provides a self-expanding filler for protecting pile foundations from freezing damage in cold regions. The self-expanding filler is used to fill the pit 16 where the pile foundation 2 is set to prevent the pile foundation 2 from freezing. Figure 1 .

[0027] Specifically, refer to Figure 2~3 The self-expanding filler 3 includes a flexible fabric bag and a soil body 15 in the bag. The soil body 15 in the bag is filled in the flexible fabric bag. After filling, the self-expanding filler 3 is in a Y shape.

[0028] In this embodiment, the self-expanding filler 3 includes a flexible section 31 and two bifurcated self-expanding sections 32, and the flexible section 31 and the two self-expanding sections 32 are integrally arranged without a breakpoint reconnection portion, and the opening is at the end of the flexible section 31. When filling, a plurality of self-expanding fillers 3 need to be stacked in the pit 16, and the adjacent two self-expanding fillers 3 are placed in opposite directions.

[0029] In this embodiment, the inner sides of the two self-expanding sections 32 of the self-expanding filler 3 are respectively provided with plastic plates 3223, and the plastic plates 3223 of the two self-expanding sections 32 are connected as one body, and the plastic plates 3223 are fixedly connected to the flexible fabric bag wall. The plastic plates 3223 are composite plates, including a perforated plastic water-permeable plate 32231 and a water-permeable membrane 32232 that are attached to each other. Figure 5 The inner side of the perforated plastic water-permeable plate 32231 contacts the water-absorbing and swelling particles 3222, the water-permeable membrane 32232 is arranged on the outer side of the perforated plastic water-permeable plate 32231, and the water-permeable membrane 32232 is fixedly connected to the flexible fabric bag wall. The structure of the perforated plastic water-permeable plate 32231 and the water-permeable membrane 32232 is conducive to the discharge of moisture from the soil 15 in the bag.

[0030] When the soil is not frozen, the self-expanding filler 3 is in close contact with the pile foundation 2, and there is friction between the two, so the pile foundation 2 can give full play to its own bearing performance. When the soil is frozen, the soil 15 in the bag of the self-expanding filler 3 expands. Under the restraining effect of the flexible fabric bag, the expansion is limited and mainly occurs horizontally. Under the guidance of the plastic plate 3223, the two self-expanding sections 32 move to both sides respectively, and the angle between the two self-expanding sections 32 becomes larger, which enhances the contact between the self-expanding filler 3 and the pile foundation 2 and the contact between the self-expanding fillers 3, and suppresses the occurrence of the frozen pull phenomenon of the pile foundation 2.

[0031] The present invention stacks the self-expanding filler 3 in the pit 16, with two adjacent self-expanding fillers 3 placed in opposite directions, and utilizes a Y-shaped structure, which effectively avoids the uneven deformation phenomenon that may occur after the self-expanding filler 3 is stacked, enhances the contact effect between the pile and the self-expanding filler, ensures the long-term effectiveness of the contact between the pile and the self-expanding filler, and at the same time fully utilizes the constraint of the self-expanding filler 3 on the soil 15 in the bag, realizes the dispersion of deformation stress, weakens the influence of frost heave on the pile foundation, and effectively prolongs the service life of the structure.

[0032] Example 2

[0033] This embodiment provides a self-expanding filler for protecting pile foundations from freezing damage in cold regions. The difference from the structure disclosed in Embodiment 1 is that this embodiment is provided with inner water absorption mechanisms 322 on the inner sides of the two self-expanding sections 32 of the self-expanding filler 3 for absorbing moisture from the soil 15 in the bag.

[0034] Specifically, refer to Figure 5 In this embodiment, the inner water absorption mechanism 322 includes an elastic water-permeable coating 3221, a plurality of water-absorbing and swellable particles 3222, and a plurality of water-conducting fibers 32211. The elastic water-permeable coating 3221 is an elastic water-permeable film with a certain tensile strength, which is arranged on the inner side of the plastic plate 3223 (i.e., the side facing the soil 15 in the bag) and connected to the soil 15 in the bag, and there is an interlayer between the elastic water-permeable coating 3221 and the plastic plate 3223, and the water-absorbing and swellable particles 3222 are filled in the interlayer and present a particle flow state. The water-absorbing and swellable particles 3222 absorb water and shrink when they lose water. The water-conducting fibers 32211 are arranged on the elastic water-permeable covering film 3221, and are in contact with the soil 15 in the bag and the water-absorbing and expanding particles 3222 respectively, thereby increasing the migration rate of moisture from the soil 15 in the bag to the water-absorbing and expanding particles 3222, and laterally blocking the migration of moisture between the pile and the soil, thereby reducing the moisture content between the self-expanding filler 3 and the pile foundation 2, thereby preventing the pile foundation 2 from freezing.

[0035] In the present invention, the elastic water-permeable coating 3221 utilizes its own elastic properties to constrain the internal water-absorbing and expanding particles 3222, effectively avoiding soil pollution caused by the water-absorbing and expanding particles 3222 scattering into the soil, ensuring the polarized distribution of water inside the expanding filler, and effectively reducing the moisture content of the soil inside the expanding filler.

[0036] Example 3

[0037] This embodiment provides a self-expanding filler for protecting pile foundations from freezing damage in cold regions. The difference from the structure disclosed in Example 2 is that this embodiment describes the structure of the water-absorbing and expanding particles 3222 in detail.

[0038] Specifically, refer to Figure 6 In this embodiment, the water-swelling particle 3222 is a polyhedral spherical structure, and each face is a triangle. The water-swelling particle 3222 includes a central body and a plurality of triangular frames (the triangular frame material is a strong fatigue-resistant material with rigidity). The central body is a spherical water-swelling rubber. Each triangular frame is fixed on the surface of the central body. Two adjacent triangular frames share one side, and the side length of the triangular frame increases / decreases with the expansion / contraction of the central body, that is, the triangular frame is a triangular block unit that can be deformed with the expansion of the central body, and its shape does not change after complete deformation.

[0039] In this embodiment, each side of the triangular frame includes a moving side 32222 and two fixed sides 32221 of the same length. In the unexpanded state, the two fixed sides 32221 are connected, the fixed sides 32221 and the moving side 32222 are distributed up and down, and the fixed sides 32221 and the moving side 32222 are slidably connected. The fixed sides 32221 are connected to the central body (a connecting block is provided at the end of the fixed side 32221, the length of the connecting block is not less than the thickness of the moving side 32222, and the fixed sides 32221 are connected to the central body through the connecting block). When the central body absorbs water and expands, the central body drives the two fixed sides 32221 to move away from each other along the moving side 32222; when the central body loses water and shrinks, the central body drives the two fixed sides 32221 to move toward each other along the moving side 32222.

[0040] In this embodiment, the fixed edge 32221 is provided with a single-ball slider 32224, and correspondingly, the moving edge 32222 is provided with a guide rail 32223 whose shape and size are mutually adapted to the single-ball slider 32224. Both the guide rail 32223 and the single-ball slider 32224 are magnetic, and the two are in a state of repelling each other with the same poles. The single-ball slider 32224 is in a magnetic suspension state in the guide rail 32223. This magnetic suspension connection technology can effectively realize the normal contraction and expansion of the overall structure in the low temperature environment of the frozen soil area, and at the same time reduce the failure rate of the structure operation process in the frozen soil environment.

[0041] In the present invention, the water-swelling particles 3222 squeeze the external triangular frame through the outward tension formed by the internal central body (spherical water-swelling rubber) after absorbing water and swelling, causing the triangular frame to deform, thereby causing the water-swelling particles 3222 to expand outward. At the same time, after losing water, under the squeezing action of the elastic water-permeable coating 3221, the deformed triangular frame returns to its original state, and the water-swelling particles 3222 return to their initial state. This structure effectively avoids the occurrence of mutual adhesion of the water-swelling particles 3222 after expansion, prevents the cracking and spreading of rubber under low temperature conditions, prolongs the service life of the structure, and effectively blocks the migration of water between the pile and the soil. At the same time, compared with the soil, the water-swelling particles 3222 have better thermal insulation performance, which indirectly slows down the temperature change of the soil around the pile.

[0042] Example 4

[0043] This embodiment provides a self-expanding filler for protecting pile foundations from freezing damage in cold regions. The difference from the structure disclosed in Embodiment 3 is that this embodiment is provided with outer water absorption mechanisms 321 on the outer sides of the two self-expanding sections 32 of the self-expanding filler 3 for absorbing moisture from the soil 15 in the bag.

[0044] Specifically, refer to Figure 4 In this embodiment, the outer water absorption mechanism 321 includes a plurality of water-absorbing rubber monomers 3211, and the plurality of water-absorbing rubber monomers 3211 are connected to form a honeycomb structure, and one side of the honeycomb structure is bonded to the inner wall of the flexible fabric bag. The cross section of the water-absorbing rubber monomer 3211 is a hexagon, and the longitudinal section is a pentagon formed by a combination of a rectangle and a triangle, and the convex part of the vertex of the bottom triangle is connected to the soil 15 in the bag, which can effectively increase the contact area between the water-absorbing rubber monomer 3211 and the soil 15 in the bag, and can use the excellent buffering performance of rubber to effectively avoid the damage to the bag structure caused by the uneven stress generated by the deformation of the soil 15 in the bag due to the influence of the environment, and effectively extend the service life of the flexible fabric.

[0045] In this embodiment, a central drainage pipe 3213 is provided at the connection node of three adjacent water-absorbing rubber monomers 3211, and two ends of the central drainage pipe 3213 are respectively connected to the soil 15 in the bag and the inner wall of the flexible fabric bag.

[0046] In this embodiment, a honeycomb outer wall 3212 is fixed outside the water-absorbing rubber monomer 3211, and the honeycomb outer wall 3212 is a prestressed structure. In the non-water-absorbing state, the water-absorbing rubber monomer 3211 is in a contracted state, and due to the contraction effect, a number of cavities 3214 are formed in the honeycomb structure. When the water-absorbing rubber monomer 3211 absorbs water and expands, the honeycomb outer wall 3212 is affected by the outward expansion effect generated by the water-absorbing rubber monomer 3211, and the stress state of the honeycomb outer wall 3212 tends to the deformation threshold. After continuing to absorb water and expand, the outward tension of the water-absorbing rubber monomer 3211 is greater than the prestress threshold of the honeycomb outer wall 3212, and the honeycomb outer wall 3212 becomes a hexagonal honeycomb structure, and the cavities 3214 disappear. After the water-absorbing rubber monomer 3211 is dehydrated, the honeycomb outer wall 3212 returns to the non-water-absorbing state structure.

[0047] In this embodiment, the cavity 3214 exists when the water-absorbing rubber monomer 3211 has not absorbed water, and disappears after the water-absorbing rubber monomer 3211 has absorbed water. The cavity 3214 cooperates with the central drainage pipe 3213 to effectively ensure that the internal moisture of the self-expanding filler 3 in the absence of precipitation is transported outward, thereby avoiding the expansion and cracking damage caused by the self-expanding filler 3 being over-saturated with water in the continuous rainfall state.

[0048] The present invention utilizes the property of the water-absorbing rubber monomer 3211 that expands after absorbing water, and arranges water-absorbing layer belts at different parts of the bag body, thereby effectively achieving the step-by-step expansion of the self-expanding filler 3 and avoiding the destruction of the self-expanding filler 3 caused by short-term high stress.

[0049] Example 5

[0050] This embodiment provides a method for protecting pile foundation from freezing damage in cold regions, which can prevent and control the freezing-extraction phenomenon of pile foundation, and includes the following steps: Step 1: Arrange the pile foundation according to the designed marked position. The pile foundation can be cast-in-place piles or precast piles.

[0051] Step 2: With the pile foundation as the center, excavate the pit according to the designed size, open four collecting grooves 4 outside the pit 16 (the depth of the collecting groove 4 is greater than the pit depth), and the four collecting grooves 4 are arranged in a cross shape with the pile foundation as the center. Adjacent collecting grooves 4 are independent of each other, and the pit 16 and the collecting groove 4 are both located above the freezing front. Figure 7 .

[0052] Step 3: a heat transfer tube 42 with a hollow interior is arranged in the collecting tank 4, and a hose 41 is buried between the heat transfer tube 42 and the collecting tank 4. One end of the hose 41 is connected to the corner of the pit 16 (the pit 16 has a certain inclination angle), and the other end is connected to the heat transfer tube 42 (a hole is provided on the side wall of the heat transfer tube 42). The hose 41 is buried at a certain downward inclination angle. Figure 7 .

[0053] Step 4: The soil generated by the on-site construction is retained and dried. After drying, debris is removed from the soil and the soil is dried and placed aside for later use.

[0054] Step 5: Fill the dried soil into the flexible fabric bag to obtain the self-expanding filler 3 disclosed in Example 4.

[0055] Step 6, arrange the self-expanding fillers 3 in layers in the pit 16. When placing, the self-expanding fillers 3 of the upper and lower adjacent layers are placed in opposite directions, that is, the end of the flexible segment 31 of the self-expanding filler 3 distributed in the pth layer is closely connected to the pile foundation 2, and the ends of the two self-expanding segments 32 of the self-expanding fillers 3 distributed in the p+1 layer and the p-1 layer are closely connected to the pile foundation 2. In addition, the placement directions of two adjacent self-expanding fillers 3 in the same horizontal layer are also opposite. If the pit 16 is a multi-step pit, the self-expanding filler 3 is placed from bottom to top. After the self-expanding filler 3 is placed at each step, the step is leveled, and the next step operation is continued after the leveling is completed.

[0056] Step 7: After the self-expanding filler 3 is placed in the pit, the self-expanding filler 3 is connected to the pile foundation 2, and the original soil is used to cover the self-expanding filler 3 to form a covering layer 14. The height of the soil around the pile after repair is lower than the height of the groove of the collecting trough 4.

[0057] Reference Figure 1 Under normal conditions, the soil surface is in the original ground surface state 11. Under negative temperature conditions, the water in the soil freezes and expands, and the soil surface presents a frozen ground surface state 12 without self-expanding filler. After the soil around the pile is replaced with self-expanding filler 3, the soil surface presents a frozen ground surface state 13 covered with self-expanding filler under negative temperature conditions. Figure 1 It can be seen that compared with the solution of filling the pit around the pile with soil, the solution of filling the pit around the pile with the self-expanding filler 3 of the present invention can suppress the freezing and pulling phenomenon of the pile foundation.

[0058] The single-step or multi-step structural design of the pit of the present invention forms a single or multiple pile-soil spacing distances, which effectively reduces the construction excavation volume while ensuring the barrier of water migration and the mitigation of temperature changes. At the same time, the pit 16 design with a certain inclination angle greatly improves the drainage efficiency and avoids water retention.

[0059] The present invention can effectively drain the accumulated water generated by seasonal melt water or external precipitation in the pit 16 by providing a hose 41 and a heat transfer tube 42, and can evaporate the accumulated water by solar heating, thereby avoiding the flexible self-expanding filler 3 from being in a soaked state for a long time, thereby ensuring the strength of the self-expanding filler 3 during use, and further ensuring the effect of inhibiting the freeze-pullout phenomenon of the pile foundation, effectively extending the service life of the entire system.

[0060] The present invention uses a flexible fabric bag to fill the soil to obtain a self-expanding filler 3, and replaces all or part of the soil between the ground and the soil freezing front, breaking the original single weak surface of stiffness difference, forming multiple stiffness difference surfaces, enhancing the contact effect of the pile bag, and giving full play to the strong water absorption characteristics of the flexible fabric to form a moisture barrier around the pile. The freezing pullout phenomenon of the pile foundation in cold areas is suppressed from multiple aspects such as enhancing the contact effect, dispersing deformation stress, blocking moisture migration, and slowing down temperature changes.

[0061] The above are only preferred embodiments of the present invention, and the protection scope of the present invention is not limited to the above embodiments. All technical solutions under the concept of the present invention belong to the protection scope of the present invention. It should be pointed out that for ordinary technicians in this technical field, some improvements and modifications without departing from the principle of the present invention should be regarded as the protection scope of the present invention.

Claims

1. A method for protecting pile foundation from freezing damage in cold regions, characterized in that: A plurality of self-expanding fillers (3) are arranged in a pit (16) where a pile foundation (2) is arranged; The self-expanding filler (3) comprises a flexible fabric bag and soil (15) in the bag, wherein the soil (15) in the bag is filled inside the flexible fabric bag; the self-expanding filler (3) is Y-shaped, comprising a flexible section (31) and two bifurcated self-expanding sections (32), wherein the flexible section (31) and the two self-expanding sections (32) are integrally arranged; a plurality of self-expanding fillers (3) are stacked in the pit (16), and two adjacent self-expanding fillers (3) are placed in opposite directions; In a non-frozen state, the self-expanding filler (3) is in close contact with the pile foundation (2); in a frozen state, the soil in the self-expanding filler (3) expands, thereby enhancing the contact effect with the pile foundation (2) and preventing the pile foundation (2) from freezing.

2. The cold region pile foundation frost damage protection method according to claim 1 is characterized in that: Plastic plates (3223) are respectively arranged inside the two self-expanding sections (32) of the self-expanding filler (3), and the plastic plates (3223) of the two self-expanding sections (32) are connected together as a whole; The plastic plate (3223) and the flexible fabric bag wall are fixed to each other. After the soil is frozen, the soil (15) in the bag expands, and under the guidance of the plastic plate (3223), the two self-expanding sections (32) move to both sides respectively, and the angle between the two self-expanding sections (32) increases.

3. The cold region pile foundation frost damage protection method according to claim 2 is characterized in that: An inner water absorption mechanism (322) is provided inside the self-expanding section (32); The inner water absorption mechanism (322) comprises an elastic water-permeable covering membrane (3221), a plurality of water-absorbing and swelling particles (3222), and a plurality of water-conducting fibers (32211); The elastic water-permeable covering film (3221) is arranged on the inner side of the plastic plate (3223), and there is an interlayer between the elastic water-permeable covering film (3221) and the plastic plate (3223), and the water-absorbing and swelling particles (3222) are filled inside the interlayer; the water-absorbing and swelling particles (3222) absorb water and expand, and lose water and shrink; The water-conducting fibers (32211) are in contact with the soil (15) in the bag and the water-absorbing and swelling particles (3222) respectively.

4. The cold region pile foundation frost damage protection method according to claim 3 is characterized in that: The water-swelling particle (3222) is a multi-faceted spherical structure, and each face is in the shape of a triangle. The water-swelling particle (3222) comprises a central body and a plurality of triangular frames. The central body is a spherical water-swelling rubber. Each triangular frame is fixed on the surface of the central body. Two adjacent triangular frames share one side, and the side length of the triangular frame increases / decreases as the central body expands / contracts. Each side of the triangular frame includes a moving side (32222) and two fixed sides (32221) of the same specification, the fixed sides (32221) and the moving sides (32222) are distributed up and down, and the fixed sides (32221) and the moving sides (32222) are slidably connected; The fixed edges (32221) are connected to the central body. When the central body absorbs water and expands, the central body drives the two fixed edges (32221) to move away from each other along the moving edge (32222); when the central body loses water and shrinks, the central body drives the two fixed edges (32221) to move toward each other along the moving edge (32222).

5. The method for protecting pile foundation from freezing damage in cold regions according to claim 4, characterized in that: The fixed edge (32221) is provided with a single-ball slider (32224), and correspondingly, the movable edge (32222) is provided with a guide rail (32223) whose shape and size are mutually compatible with the single-ball slider (32224); The guide rail (32223) and the single-ball slider (32224) are both magnetic, and the two are in a state of repelling each other with the same poles. The single-ball slider (32224) is in a state of magnetic suspension in the guide rail (32223).

6. The method for protecting pile foundation from freezing damage in cold regions according to claim 2, characterized in that: The plastic plate (3223) comprises a perforated plastic water-permeable plate (32231) and a water-permeable membrane (32232) which are attached to each other; The inner side of the perforated plastic water-permeable plate (32231) is in contact with the water-absorbing and swelling particles (3222), and the water-permeable membrane (32232) is arranged on the outer side of the perforated plastic water-permeable plate (32231).

7. The cold region pile foundation frost damage protection method according to claim 1 is characterized in that: An outer water absorption mechanism (321) is provided on the outer side of the self-expanding section (32); The outer water absorption mechanism (321) comprises a plurality of water-absorbing rubber monomers (3211) having a hexagonal cross section, wherein the plurality of water-absorbing rubber monomers (3211) are connected to form a honeycomb structure, wherein one side of the honeycomb structure is fixedly connected to the inner wall of the flexible fabric bag, and the other side is in contact with the soil (15) in the bag; a central drainage pipe (3213) is provided at the connection node of three adjacent water-absorbing rubber monomers (3211), and the two ends of the central drainage pipe (3213) are respectively connected to the soil (15) in the bag and the inner wall of the flexible fabric bag; A honeycomb outer wall (3212) is fixed outside the water-absorbing rubber monomer (3211), and the honeycomb outer wall (3212) is a prestressed structure. In a non-water-absorbing state, the water-absorbing rubber monomer (3211) is in a contracted state.

8. The cold region pile foundation frost damage protection method according to claim 7 is characterized in that: The longitudinal section of the water-absorbing rubber monomer (3211) is a pentagon formed by combining a rectangle and a triangle up and down, and the convex part of the vertex of the bottom triangle is connected to the soil (15) in the bag.

9. The cold region pile foundation frost damage protection method according to claim 1, characterized in that: The method further comprises: At least one group of collecting grooves (4) is provided outside the pit (16), a heat transfer pipe (42) with a hollow interior is provided inside the collecting groove (4), and a hose (41) is provided between the heat transfer pipe (42) and the pit (16), and the heat transfer pipe (42) is connected to the pit (16) through the hose (41).

10. The cold region pile foundation frost damage protection method according to claim 1, characterized in that: The pit (16) is a single-layer pit or a multi-step pit. When the pit (16) is a multi-step pit, the self-expanding filler (3) is placed from bottom to top. After the self-expanding filler (3) is placed at each step, the step is leveled. After the leveling is completed, the next step operation is continued.

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