A steel pipe composite pile foundation reinforcement structure suitable for frozen soil

Abstract

This utility model relates to a steel pipe composite pile foundation reinforcement structure suitable for frozen soil, comprising a steel pipe composite pile, wherein the pile bottom is located in the permafrost layer, the steel pipe composite pile includes a steel pipe concrete core pile and a cement mixing body, the steel pipe concrete core pile being inserted into the cement mixing body, the cement mixing body being composed of thawed frozen soil and cement slurry uniformly mixed, and a refreezing layer being provided around the cement mixing body. The advantages of this utility model are: it can resist the repeated compression of the pile body by freeze-thaw cycles; it can resist the repeated pull-out effects of freeze-thaw cycles on the pile body; it maintains the strength of the pile body at all times, ensuring that the roadbed does not undergo large deformations; it has high bearing capacity, as the soil friction force is obtained through the surrounding mixing piles, resulting in high bearing capacity of the steel pipe composite pile.

Description

Technical Field

[0001] This utility model relates to the field of frozen soil reinforcement technology, and in particular to a steel pipe composite pile foundation reinforcement structure suitable for frozen soil. Background Technology

[0002] Currently, the main methods for reinforcing frozen soil foundations are thermal insulation and conventional precast piles or bored piles. These methods have the following main problems: 1) Insulation measures cannot completely eliminate the effects of freeze-thaw cycles on frozen soil, especially in high-temperature frozen soil areas where the deformation caused by freeze-thaw cycles is significant.

[0003] 2) Traditional pile foundation construction generates heat, which disrupts the temperature field of the permafrost layer and causes a thawing zone to form around the pile foundation. The thawing zone takes a long time to refreeze, which significantly reduces the bearing capacity of the pile foundation.

[0004] 3) During freeze-thaw cycles, frozen soil freezes and expands, repeatedly exerting significant pressure on the pile foundation and damaging its structure.

[0005] 4) During freeze-thaw cycles, frozen soil expands and undergoes upward expansion deformation, which repeatedly exerts a large pull-out force on the pile foundation. When the pile foundation has weak pull-out strength, it is easy to break the pile.

[0006] 5) After the frozen soil thaws, the side resistance of the piles in the thawed section decreases significantly, and the bearing capacity decreases.

[0007] 6) During freeze-thaw cycles, repeated compression and pulling of the pile foundation gradually reduces its strength, eventually leading to its failure. Summary of the Invention

[0008] The purpose of this invention is to address the shortcomings of the prior art by providing a steel pipe composite pile foundation reinforcement structure suitable for frozen soil. This structure can eliminate the impact of pile foundation construction heat on frozen soil, and during freeze-thaw cycles, it can resist repeated compression and pull-out of frozen soil and cyclical changes in the magnitude of pile body stress, ensuring the service life of the pile foundation while preventing large deformation of the supporting superstructure.

[0009] The objective of this utility model is achieved through the following technical solution: A steel pipe composite pile foundation reinforcement structure suitable for frozen soil is disclosed for foundation reinforcement in frozen soil areas, which include an active layer and a permafrost layer below it. The structure comprises steel pipe composite piles, the pile bottom of which is located within the permafrost layer. Each steel pipe composite pile includes a steel pipe concrete core pile and a cement mixing body. The steel pipe concrete core pile is inserted into the cement mixing body, which is composed of thawed frozen soil and cement slurry uniformly mixed. A refreezing layer is provided around the cement mixing body.

[0010] The steel-concrete composite core pile includes a steel pipe and fine aggregate concrete poured inside the steel pipe.

[0011] The outer wall of the steel pipe is reinforced with ribs.

[0012] The advantages of this utility model are: 1) Steel-concrete composite structures have high compressive and shear strength, and can resist repeated compression of the pile body by freeze-thaw cycles.

[0013] 2) The steel pipe has high tensile strength and can resist the repeated pull-out effects of freeze-thaw cycles on the pile body.

[0014] 3) By increasing the length and friction of the pile body in the permafrost zone, the pile foundation can maintain its strength under the repeated tension and compression of the freeze-thaw cycle, ensuring that the roadbed does not undergo large deformation.

[0015] 4) Steel-concrete composite structures have high bearing capacity. They obtain soil friction through surrounding mixing piles, resulting in high bearing capacity of steel-concrete composite piles. Attached Figure Description

[0016] Figure 1 Construction steps of this utility model Figure I ; Figure 2 Construction steps of this utility model Figure II ; Figure 3 Construction steps of this utility model Figure III ; Figure 4 Construction steps of this utility model Figure IV ; Figure 5 Construction steps of this utility model Figure V ; Figure 6 Construction steps of this utility model Figure VI ; Figure 7 Construction steps of this utility model Figure VII . Detailed Implementation

[0017] The features and other related features of this utility model will be further described in detail below with reference to the accompanying drawings and embodiments, so as to facilitate the understanding of those skilled in the art: like Figure 1-7 As shown in the figure, the markings represent: cement slurry pump 1, grouting hose 2, mixing head 3, hollow steel pipe 4, grouting steel pipe 5, rotary power head 6, frame 7, active layer 8, permafrost layer 9, borehole 10, thawed frozen soil around the borehole 11, air duct 12, cold air collection device 13, thawing ring 14, cement mixing body 15, refreezing layer 16, ribbed 17, fine aggregate concrete 18, and steel pipe 19.

[0018] Example: Figures 1 to 7 As shown, the steel pipe composite pile foundation reinforcement structure suitable for frozen soil in this embodiment can be widely used in various frozen soil foundation treatment projects and has broad application prospects. In this embodiment, the frozen soil area includes an active layer 8 and a permafrost layer 9, wherein the active layer 8 is located above the permafrost layer 9. The active layer 8 refers to the stratum that thaws in summer and freezes in winter, while the permafrost layer 9 refers to the stratum that is frozen all year round.

[0019] The steel pipe composite pile foundation reinforcement structure suitable for frozen soil in this embodiment includes the following specific steps during construction: 1) such as Figure 1 As shown, a drilling rig is used to drill a hole to the designed pile length, forming borehole 10. The diameter of borehole 10 can be slightly smaller than the designed pile diameter, but it must meet the pipe diameter requirements of the subsequently inserted steel pipe 19.

[0020] 2) such as Figure 2 As shown, a steel pipe 19 is inserted into the borehole 10. This steel pipe 19 is a hollow steel pipe. Hot water is injected to heat the frozen soil around the borehole, causing it to thaw and form thawed frozen soil 11. The thawing range of the frozen soil around the borehole is larger than the designed pile diameter.

[0021] 3) such as Figure 3 As shown, this is a construction tool for erecting steel pipe composite piles. The tool includes a rotary power head 6, which is mounted on a frame 7.

[0022] 4) such as Figure 4 As shown, the rotary power head 6 can rotate under power drive. The rotary power head 6 holds the hollow steel pipe 4 and rotates it, causing the mixing head 3 at the bottom of the hollow steel pipe 4 to rotate and cut the soil. Simultaneously, the cement slurry pump 1 sprays cement slurry into the mixing head 3 through the grouting hose 2 and the grouting steel pipe 5. The thawed frozen soil 11 around the hole is fully mixed with the cement slurry under the mixing head 3 to form a cement mixture 15. At the same time, the frame 7 drives the steel pipe 4 and the mixing head 3 to sink and mix in the soil. If remixing is required, the frame 7 can also drive the steel pipe 4 and the mixing head 3 to move up and down repeatedly to complete the remixing. When the pile length is long, the hollow steel pipe 4 can be extended section by section during construction. The construction of the hollow steel pipe 4 and the cement mixture 15 should be completed before winter as much as possible.

[0023] 5) such as Figure 5As shown, after the hollow steel pipe 4 and cement mixing body 15 are constructed, during winter, a venting pipe 12 is placed inside the hollow steel pipe 4 to the bottom of the pipe. A trumpet-shaped cold air collection device 13 is installed at the top of the venting pipe 12. At this time, due to the low surface temperature (-10 to -30℃), strong winds, and long wind duration in the frozen soil area during winter, the cold air from the surface is introduced into the hollow steel pipe 4 through the venting pipe 12 as a cold source, continuously and significantly reducing the thawing zone 14 and the temperature of the frozen soil around the hollow steel pipe 4. The thawing zone 14 refers to the portion of the frozen soil around the hole that is larger than the designed pile diameter in step 2) above.

[0024] 6) For example Figure 6 As shown, through the continuous cooling of the air pipe 12, after a period of time, the hollow steel pipe 4 at a low temperature is frozen, and the thawed frozen soil 11 around the hole, including the melting zone 14, is re-frozen to form a re-frozen layer 16. Moreover, the temperature of the frozen soil around the pile is also lower than its constant temperature.

[0025] 7) For example Figure 7 As shown, fine aggregate concrete 18 is poured into the hollow steel pipe 4 to form a rigid-flexible composite pile with a steel-concrete core and a cement mixing body 15 around it. The melting zone 14 around the pile is eliminated, and the foundation in the frozen soil area is reinforced through this steel-concrete composite pile. In this embodiment, to further improve the connection performance between the core pile and the cement mixing body 15, several reinforcing ribs 17 are uniformly provided on the outer wall of the hollow steel pipe 4.

[0026] Although the above embodiments have described the concept and embodiments of the present invention in detail with reference to the accompanying drawings, those skilled in the art will recognize that various improvements and modifications can still be made to the present invention without departing from the scope of the claims, and therefore will not be elaborated here.

Claims

1. A steel pipe composite pile foundation reinforcement structure suitable for frozen soil, used for foundation reinforcement in frozen soil areas, the frozen soil area comprising an active layer and an underlying permafrost layer, characterized in that: The invention includes steel pipe composite piles, the pile bottom of which is located in the permafrost layer. The steel pipe composite pile includes a steel pipe concrete core pile and a cement mixing body. The steel pipe concrete core pile is inserted into the cement mixing body, which is composed of thawed frozen soil and cement slurry after uniform mixing. A refreezing layer is provided around the cement mixing body.

2. The steel pipe composite pile foundation reinforcement structure suitable for frozen soil according to claim 1, characterized in that: The steel-concrete composite core pile includes a steel pipe and fine aggregate concrete poured inside the steel pipe.

3. The steel pipe composite pile foundation reinforcement structure suitable for frozen soil according to claim 2, characterized in that: The outer wall of the steel pipe is reinforced with ribs.

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