Spiral anchor foundation suitable for frozen earth area and construction method thereof

Abstract

The spiral anchor foundation suitable for the frozen soil area comprises an upper structure, at least one round steel pipe is connected to the lower portion of the upper structure, an anchor rod is connected to the lower portion of each round steel pipe, a heat insulation device is arranged between the round steel pipes and the anchor rods, and the round steel pipes, the heat insulation device and the anchor rods are fixed together through bolts. And at least one anchor rod is arranged below the superstructure. The spiral anchor foundation suitable for the frozen soil area has the following beneficial effects that heat conduction can be eradicated or reduced, the freeze-thaw effect under the spiral anchor foundation is effectively reduced, the situation that the ecological environment of the frozen soil area is affected and the bearing capacity of the foundation is reduced due to thawing of the frozen soil of the foundation is prevented, and therefore the design reliability level of the spiral anchor foundation is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of power transmission and transformation engineering, and specifically relates to several spiral anchor foundations suitable for frozen soil areas and construction methods thereof. The present invention is suitable for sites with high altitudes, frozen soil layers, good traffic conditions, and convenient access and operation of mechanical equipment. Except for rock and gravel soil, other soil types can be used. Background Art

[0002] Frozen soil refers to various rocks and soils below zero degrees Celsius and containing ice. When constructing engineering buildings and structures in frozen soil areas, the effects of frost heave and thaw settlement must be considered. In addition, in order to protect the ecological environment of frozen soil areas, it is necessary to avoid disturbing the frozen soil as much as possible. At present, independent concrete foundations and pile foundations are often used in domestic engineering construction in frozen soil areas. When pouring concrete foundations, a large amount of hydration heat will be generated, and the excavation range of earthwork is large, which is easy to disturb the frozen soil foundation, have a great impact on the ecological environment of frozen soil areas, and is not conducive to the bearing capacity of the foundation. In addition, concrete foundations require a long maintenance time. The current common practice is to wait for a freeze-thaw cycle before constructing the superstructure, and the construction period is very long.

[0003] The spiral anchor foundation is an anchor structure composed of spiral anchors and upper caps, which mainly uses deep soil to resist the force of the upper structure. The foundation is mainly steel components, prefabricated in factories, and has stable foundation quality. The foundation adopts mechanized construction, with fewer construction processes and simple construction, which can significantly reduce or avoid the use of concrete materials, thereby greatly shortening the construction period. At the same time, there is no need for large-scale excavation during spiral anchor construction, the scope of surface damage is relatively small, and the disturbance to the soil is also small, which can give full play to the inherent strength of the original soil and save foundation materials. Therefore, the use of spiral anchor foundation can well avoid the shortcomings of large hydration heat and long construction period of concrete foundation in frozen soil areas. However, the traditional spiral anchor foundation is a full steel structure, and the thermal conductivity of steel is significantly greater than that of concrete. The upper heat is easily conducted downward along the anchor rod, causing the lower frozen soil to melt, affecting the ecological environment of the frozen soil area, and is not conducive to the foundation bearing. Therefore, it is urgent to propose a new type of spiral anchor foundation that can avoid the heat of the upper structure from being conducted downward along the anchor rod. Summary of the invention

[0004] The technical problem to be solved by the present invention is: how to solve the problem of heat conduction of the upper structure downward along the anchor rod when the existing spiral anchor foundation is applied to frozen soil areas, and to provide several spiral anchor foundations suitable for frozen soil areas and construction methods thereof.

[0005] To solve the above problems, the present invention is achieved through the following technical solutions: The invention discloses a spiral anchor foundation suitable for frozen soil areas, comprising an upper structure, at least one round steel pipe connected to the lower part of the upper structure, each round steel pipe connected to the lower part of the anchor rod, a thermal insulation device arranged between the round steel pipe and the anchor rod, and the round steel pipe, the thermal insulation device and the anchor rod fixed together by bolts.

[0006] At least one anchor rod is arranged below the superstructure.

[0007] The thermal insulation device means that each round steel pipe is connected to the anchor rod through a flange; the flange includes two upper and lower flange bodies, and a thermal insulation device is arranged between the upper and lower flange bodies, and the thermal insulation device refers to a thermal insulation board.

[0008] Two gaskets are arranged between the upper and lower flange bodies, and a heat-insulating plate is arranged between the two gaskets; the upper and lower flange bodies, the two gaskets and the heat-insulating plate are connected by at least one first bolt.

[0009] The backing plate is a steel backing plate, the size of which is larger than the outer diameter of the flange, and a thermal insulation plate is arranged between the two steel backing plates, the size of which is the same as that of the backing plate.

[0010] The thermal insulation device refers to: the diameter of the round steel pipe is larger than the diameter of the anchor rod, and the thermal insulation device is arranged between the round steel pipe and the anchor rod. The thermal insulation device is a thermal insulation tube. The size of the thermal insulation tube is slightly larger than the anchor rod and slightly smaller than the round steel pipe of the outer casing. The round steel pipe, the thermal insulation tube and the anchor rod are fastened together by a second bolt (9).

[0011] The material of the thermal insulation device is extruded styrene board, chloroprene rubber board or rock wool.

[0012] The round steel pipes and bolts are wrapped with insulation materials.

[0013] A construction method for a spiral anchor foundation comprises the following steps: Step 1: During construction, the anchor rod of the spiral anchor should be screwed into place first; Step 2: Assemble the flange: Assemble the two gaskets, the insulation plate and the flange body together to form a flange; Step 3: Connect the flange, anchor rod and round steel pipe together and connect them to the upper structure; Step 4: Finally, the upper portion of the round steel pipe exposed above the ground is wrapped with a thermal insulation material to complete the construction of the spiral anchor foundation suitable for frozen soil areas.

[0014] A construction method for a spiral anchor foundation comprises the following steps: Step 1: During construction, the anchor rod of the spiral anchor should be screwed into place first; Step 2: Arrange a thermal insulation pipe outside the anchor rod, arrange a round steel pipe outside the thermal insulation pipe, and fasten the round steel pipe, the thermal insulation pipe and the anchor rod together with a second bolt; Step 3: Weld the round steel pipe to the upper structure; Step 4: Finally, the upper portion of the round steel pipe exposed above the ground is wrapped with a thermal insulation material to complete the construction of the spiral anchor foundation suitable for frozen soil areas.

[0015] Compared with the prior art, the present invention has the following beneficial effects: the spiral anchor foundation suitable for permafrost areas can eliminate or reduce heat conduction, effectively reduce the freeze-thaw effect under the spiral anchor foundation, prevent the melting of frozen soil in the foundation from affecting the ecological environment in the permafrost area, and cause a decrease in the bearing capacity of the foundation, thereby improving the design reliability level of the spiral anchor foundation. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 A schematic diagram of a single-anchor spiral anchor foundation suitable for frozen soil areas provided by the present invention; Figure 2 for Figure 1 Schematic diagram of section 1-1; Figure 3 A schematic diagram of a group-anchor type spiral anchor foundation suitable for frozen soil areas provided by the present invention; Figure 4 for Figure 3 Schematic diagram of section 2-2; Figure 5 A second schematic diagram of a single-anchor helical anchor foundation suitable for frozen soil areas provided by the present invention; Figure 6 for Figure 5 Schematic diagram of section 3-3. DETAILED DESCRIPTION

[0017] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only 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 creative work are within the scope of protection of the present invention.

[0018] In the description of the present invention, it is necessary to understand that the terms "upper", "lower", "front", "back", "left", "right", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0019] The invention discloses a spiral anchor foundation suitable for use in frozen soil areas, comprising an upper structure 7, at least one round steel pipe 1 being connected below the upper structure 7, and an anchor rod 6 being connected below each round steel pipe 1. A thermal insulation device is provided between the round steel pipe 1 and the anchor rod 6, and the round steel pipe 1, the thermal insulation device and the anchor rod 6 are fixed together by bolts.

[0020] Further, when one anchor rod 6 is arranged below the superstructure, it is a single anchor type spiral anchor foundation. When several anchor rods 6 are arranged below the superstructure, it is a group anchor type spiral anchor foundation; when it is a group anchor type spiral anchor foundation, there are several anchor rods 6, and the arrangement angle is a different inclination angle, and the specific angle can be determined according to theoretical calculations and actual site conditions.

[0021] Example 1 The thermal insulation device means that each round steel pipe 1 is connected to the anchor rod 6 through the flange 2. The flange 2 includes two upper and lower flange bodies, and a thermal insulation device is arranged between the upper and lower flange bodies. The thermal insulation device here refers to the thermal insulation board 4.

[0022] Preferably, two gaskets 3 are arranged between the upper and lower flange bodies, and a heat-insulating plate 4 is arranged between the two gaskets 3; the upper and lower flange bodies, the two gaskets 3 and the heat-insulating plate 4 are connected by at least one first bolt 5. In this way, the structure of the flange 2 is: the center is the heat-insulating plate 4, the gaskets 3 are arranged on the upper and lower sides of the heat-insulating plate 4, and the flange bodies are arranged on the upper and lower sides of the gaskets 3. When the first bolt 5 is connected, a bolt hole can be opened at the corresponding position, and the diameter of the bolt hole is slightly larger than the diameter of the first bolt 5. In this case, the axial direction of the first bolt 5 is consistent with the axial direction of the anchor rod 6.

[0023] Furthermore, since the stress-bearing performance of the insulation material is significantly worse than that of the steel structure, in order to ensure the safety of the structure and reduce the stress on the insulation plate 4, the present invention adds a gasket 3 between the flange 2 and the insulation plate 4. The gasket 3 is a steel gasket. The size of the steel gasket 3 should be larger than the outer diameter of the flange 2 to reduce the compressive stress. The insulation plate 4 is arranged between the two steel gaskets, and the size of the insulation plate 4 can be the same as that of the gasket 3.

[0024] The insulation board 4 can be made of extruded styrene board, chloroprene rubber board, rock wool, etc.

[0025] The first bolt 5 and the round steel pipe 1 are wrapped with rock wool to prevent heat transfer between the flange 2. During construction, after the anchor rod 6 of the spiral anchor is screwed in, the round steel pipe 1 is wrapped with thermal insulation materials such as rock wool to prevent absorption of external heat.

[0026] Furthermore, the first bolt 5 is made of a new type of carbon fiber material.

[0027] The construction method of this embodiment includes the following steps: Step 1: During construction, the anchor rod 6 of the spiral anchor should be screwed into place first; Step 2: Assembling the flange 2: Assemble the two gaskets 3, the insulation plate 4 and the flange body together to form the flange 2; Step 3: Connect the flange 2, anchor rod 6 and round steel pipe 1 together, and connect them to the upper structure 7; Step 4: Finally, the upper portion of the round steel pipe 1 exposed above the ground is wrapped with thermal insulation materials such as rock wool to complete the construction of the spiral anchor foundation suitable for frozen soil areas.

[0028] Example 2 The heat-insulating device means: the diameter of the round steel pipe 1 is larger than the diameter of the anchor rod 6, and a heat-insulating device is arranged between the round steel pipe 1 and the anchor rod 6. The heat-insulating device is a heat-insulating tube 8, and the size of the heat-insulating tube 8 is slightly larger than the anchor rod 6 and slightly smaller than the round steel pipe 1 of the jacket, and the round steel pipe 1, the heat-insulating tube 8 and the anchor rod 6 are fastened together by the second bolt 9. At this time, the axial direction of the second bolt 9 is perpendicular to the axial direction of the anchor rod 6.

[0029] The upper structure 7 is connected to the round steel pipe 1 by on-site welding, and the round steel pipe 1 is connected to the insulation pipe 8 and the anchor rod 6 by a second bolt 9. The insulation pipe 8 is located between the round steel pipe 1 and the anchor rod 6, and holes are drilled on the insulation pipe 8 according to the bolt hole positions on the round steel pipe 1 and the anchor rod 6.

[0030] Furthermore, the insulation pipe 8 isolates the upper structure 7 from heat transfer, preventing the melting of the frozen soil of the foundation from causing a decrease in the bearing capacity of the foundation. The material of the insulation pipe 8 can be a tubular structure made of plastic styrene, chloroprene rubber, rock wool, etc.

[0031] Furthermore, since the insulation tube 8 does not directly bear the force of the upper structure, the insulation tube 8 is not easy to be damaged. However, at this time, the second bolt 9 directly bears the force of the upper structure. If the second bolt 9 is wrapped with a heat-insulating material, the heat-insulating material is easily damaged when the second bolt 9 is subjected to force, resulting in a decrease in the heat-insulating capacity. Therefore, the second bolt 9 is made of a new carbon fiber material. The shear performance of the new carbon fiber material is weaker than that of the steel material. In actual use, it should be used after reliable calculation.

[0032] In order to avoid heat conduction from the ground surface as much as possible, the round steel pipe 1 in the present invention is wrapped with thermal insulation materials such as rock wool to avoid absorbing heat from the upper structure as much as possible.

[0033] The construction method of this embodiment is: Step 1: During construction, the anchor rod 6 of the spiral anchor should be screwed into place first; Step 2: a thermal insulation tube 8 is arranged outside the anchor rod 6, a round steel tube 1 is arranged outside the thermal insulation tube 8, and the round steel tube 1, the thermal insulation tube 8 and the anchor rod 6 are fastened together by a second bolt 9; Step 3: Weld the round steel pipe 1 to the upper structure 7; Step 4: Finally, the upper portion of the round steel pipe 1 exposed above the ground is wrapped with thermal insulation materials such as rock wool to complete the construction of the spiral anchor foundation suitable for frozen soil areas.

[0034] For the convenience of construction, a small part of the soil layer may need to be excavated during construction. When backfilling here, mixed sand, gravel and other materials can be used. Construction can only be continued after the compaction index reaches the design requirements.

[0035] As an improvement of the technical solution, the size, thickness, and material of the insulation board 4 and insulation tube 8 used in the spiral anchor foundation suitable for frozen soil areas can be determined according to the actual situation on site. In view of this, any modification or variation of the size, thickness, and material of the insulation board 4 and insulation tube 8 is deemed to be within the protection scope of the patent of this invention.

[0036] The above is only a preferred embodiment of the present invention. It should be pointed out that for those skilled in the art, several changes and improvements can be made without departing from the overall concept of the present invention, which should also be regarded as the scope of protection of the present invention.

Claims

1. A screw anchor foundation suitable for frozen soil areas, comprising a superstructure (7), characterized in that: At least one round steel pipe (1) is connected below the upper structure (7), and each round steel pipe (1) is connected below an anchor rod (6). A thermal insulation device is provided between the round steel pipe (1) and the anchor rod (6), and the round steel pipe (1), the thermal insulation device and the anchor rod (6) are fixed together by bolts.

2. The spiral anchor foundation suitable for frozen soil areas according to claim 1 is characterized in that: At least one anchor rod (6) is arranged below the superstructure (7).

3. The spiral anchor foundation suitable for frozen soil areas according to claim 1 is characterized in that: The thermal insulation device refers to: each round steel pipe (1) is connected to the anchor rod (6) through a flange (2); the flange (2) includes two upper and lower flange bodies, and a thermal insulation device is arranged between the upper and lower flange bodies, and the thermal insulation device refers to a thermal insulation board (4).

4. The spiral anchor foundation suitable for frozen soil areas according to claim 3 is characterized in that: Two gaskets (3) are arranged between the upper and lower flange bodies, and a thermal insulation plate (4) is arranged between the two gaskets (3); the upper and lower flange bodies, the two gaskets (3) and the thermal insulation plate (4) are connected by at least one first bolt (5).

5. The spiral anchor foundation suitable for frozen soil areas according to claim 3 is characterized in that: The backing plate (3) is a steel backing plate, the size of which is larger than the outer diameter of the flange (2), and a thermal insulation plate (4) is arranged between the two steel backing plates, the size of which is the same as that of the backing plate (3).

6. The spiral anchor foundation suitable for frozen soil areas according to claim 1, characterized in that: The thermal insulation device refers to: the diameter of the round steel pipe (1) is larger than the diameter of the anchor rod (6); the thermal insulation device is arranged between the round steel pipe (1) and the anchor rod (6); the thermal insulation device is a thermal insulation pipe (8); the size of the thermal insulation pipe (8) is slightly larger than the anchor rod (6) and slightly smaller than the outer sleeve of the round steel pipe (1); and the round steel pipe (1), the thermal insulation pipe (8) and the anchor rod (6) are fastened together by a second bolt (9).

7. The spiral anchor foundation suitable for frozen soil areas according to claim 1 is characterized in that: The material of the thermal insulation device is extruded styrene board, chloroprene rubber board or rock wool.

8. The spiral anchor foundation suitable for frozen soil areas according to claim 1 is characterized by: The round steel pipe (1) and the bolts are wrapped with heat insulating material.

9. A method for constructing the spiral anchor foundation according to claim 4, comprising the following steps: Step 1: During construction, the anchor rod (6) of the spiral anchor should be screwed into place first; Step 2: Assembling the flange (2): Assemble the two gaskets (3), the insulation plate (4) and the flange body together to form the flange (2); Step 3: Connect the flange (2), anchor rod (6) and round steel pipe (1) together, and connect them to the upper structure (7); Step 4: Finally, the upper portion of the round steel pipe (1) exposed above the ground is wrapped with a thermal insulation material to complete the construction of the spiral anchor foundation suitable for frozen soil areas.

10. A method for constructing the spiral anchor foundation according to claim 6, comprising the following steps: Step 1: During construction, the anchor rod (6) of the spiral anchor should be screwed into place first; Step 2: a thermal insulation tube (8) is arranged outside the anchor rod (6), a round steel tube (1) is arranged outside the thermal insulation tube (8), and the round steel tube (1), the thermal insulation tube (8) and the anchor rod (6) are fastened together using a second bolt (9); Step 3: Welding the round steel pipe (1) to the upper structure (7); Step 4: Finally, the upper portion of the round steel pipe (1) exposed above the ground is wrapped with a thermal insulation material to complete the construction of the spiral anchor foundation suitable for frozen soil areas.

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