Ice area double-protection spiral anchor group composite foundation and construction method

Abstract

The invention discloses a spiral anchor group composite foundation with dual protection in an ice region and a construction method, and belongs to the field of ice region engineering, the construction method comprises the following specific steps: I, determining the mounting positions of main anchor rods and auxiliary anchor rods according to an engineering design drawing, and implanting the main anchor rods into the foundation at a vertical or set inclination angle; iI, selecting steel bearing platforms with the number corresponding to that of the main anchor rods, welding round steel pipes at preset positions of the steel bearing platforms, and then adjusting the levelness and the plane position of each steel bearing platform in real time; iII, the flange plates, the base plates and the heat insulation plates are stacked and assembled according to a preset installation sequence, and a transverse heat insulation barrier is constructed; the method can effectively resist the complex load of the ice region, completely eradicate the thaw collapse risk, improve the foundation bearing capacity, improve the construction safety and reliability, and provide an efficient and reliable solution for the energy engineering of the ice region and the frozen soil region.

Description

Technical Field

[0001] This invention relates to the field of ice zone engineering, and in particular to a composite foundation with helical anchor groups for double protection in ice zones and its construction method. Background Technology

[0002] Amid the global energy transition, offshore wind power is rapidly emerging as a key force in clean energy. However, the challenge of supporting complex ice loads on wind turbine foundations in icy waters remains to be overcome. Simultaneously, power transmission and transformation projects in high-latitude icy and permafrost regions, along with the construction of offshore wind turbine foundations, also face significant challenges.

[0003] Existing offshore wind turbine foundations, such as monopile foundations and gravity foundations, exhibit significant drawbacks in ice-covered environments. Monopile foundations are susceptible to large bending moments and displacements due to ice thrust, and long-term ice-induced vibrations can cause structural fatigue damage. While gravity foundations offer relatively good stability, their large size and weight place stringent requirements on seabed geological conditions, resulting in high construction difficulty and costs. Furthermore, offshore wind turbine foundations in ice-covered areas face a dual technical dilemma: the compression, collision, and vibration of sea ice can induce fatigue in the foundation structure, while the heat conduction of traditional steel foundations can lead to the thawing and subsidence of the permafrost layer, threatening ground stability. Existing ice-resistant structures are mostly designed with fixed conical surfaces, making it difficult to adapt to dynamic changes in ice conditions, and there is a lack of systematic solutions for the application of helical anchor foundations in ice-covered and permafrost regions.

[0004] From the perspective of power transmission and transformation engineering and offshore wind power foundation technology, the shortcomings of existing technologies are equally significant. Icing resistance and thermal insulation functions are disconnected; traditional icing-resistant structures do not work in conjunction with permafrost insulation devices, making the insulation layer susceptible to damage from heat transfer. The arrangement of helical anchor groups is unreasonable, easily leading to anchor overload under ice thrust, and the connection points lack ice vibration resistance design. On-site welding in ice-covered areas is inefficient and of questionable quality, and detachable connection structures are prone to loosening under ice vibration. Therefore, we propose a composite foundation with helical anchor groups for dual protection in ice-covered areas and a corresponding construction method. Summary of the Invention

[0005] The purpose of this invention is to address the deficiencies in the existing technology by proposing a composite foundation with dual protection for ice-covered areas and a construction method thereof.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] The construction method of a composite foundation with dual protection against ice conditions using spiral anchor groups is as follows:

[0008] Ⅰ: Determine the installation positions of each main anchor and each auxiliary anchor according to the engineering design drawings, and implant each main anchor vertically or at a set angle into the foundation;

[0009] II: Select the corresponding number of steel bearing platforms for each main anchor rod, and weld round steel pipes at the preset positions of each steel bearing platform, and then adjust the levelness and plane position of each steel bearing platform in real time;

[0010] III: Assemble all flanges, gaskets, and insulation boards in the preset installation sequence to form a transverse thermal insulation barrier;

[0011] IV: Select the corresponding thermal insulation pipe and install it on the exposed section of each round steel pipe, and then select the corresponding outer steel pipe and install it on the outside of each thermal insulation pipe to construct a longitudinal thermal insulation barrier;

[0012] V: After construction is completed, professional equipment is used to test the entire structure for connection quality inspection, thermal insulation performance test, and anchoring and load resistance test.

[0013] As a further aspect of the present invention, the specific steps for embedding each main anchor rod into the foundation at a vertical or predetermined angle in step I are as follows:

[0014] S1.1: Mark the preset installation points of each main anchor in the construction area according to the engineering design drawings, and distribute each auxiliary anchor in a triangular array around each main anchor, with the distance between each auxiliary anchor and each main anchor being 1.5 to 2 times the diameter of each main anchor. Mark the preset installation points of each auxiliary anchor around each main anchor.

[0015] S1.2: Weld anchor plates to the lower part of each main anchor and each auxiliary anchor, and at the same time, the blades of each anchor plate are perpendicular to the axis of each corresponding main anchor and each auxiliary anchor. Then, insert each main anchor with the anchor plate welded on it into the preset installation point at a vertical angle or a set angle.

[0016] S1.3: Adjust the verticality or tilt angle deviation of each auxiliary anchor rod according to the angle at which each main anchor rod is inserted, and then insert each auxiliary anchor rod into the preset installation point with the corresponding verticality or tilt angle deviation.

[0017] As a further aspect of the present invention, the specific steps for real-time adjustment of the levelness and planar position of the steel foundation in step II are as follows:

[0018] S2.1: Select the number of steel bearing platforms corresponding to each main anchor rod according to the engineering design drawings, and mark the welding position of the round steel pipe at the bottom of each steel bearing platform. The number and position of each round steel pipe correspond one-to-one with each main anchor rod and each auxiliary anchor rod.

[0019] S2.2: Weld round steel pipes at the marked welding positions, and then use lifting equipment to hoist each steel bearing platform above each main anchor rod. Adjust the level and plane position of each steel bearing platform in real time so that the lower end of each round steel pipe is aligned with the top of each main anchor rod and each auxiliary anchor rod, and the deviation is within the preset range.

[0020] As a further aspect of the present invention, the specific steps for constructing the transverse thermal barrier in step III are as follows:

[0021] S3.1: Select a preset number of flanges, gaskets, insulation plates and first bolts, and according to the preset installation sequence, stack each flange, gasket and insulation plate at the lower end of each round steel pipe and the top of each main anchor and auxiliary anchor. Among them, the insulation plate is made of extruded polystyrene board and the gasket is made of wear-resistant steel.

[0022] S3.2: Insert each first bolt through the reserved holes of each flange, each gasket and each insulation plate, and tighten each first bolt by pre-setting graded pre-tightening. Then fill the bolt hole gaps of the first bolts with silicone rubber sealant to construct a transverse thermal insulation barrier.

[0023] As a further aspect of the present invention, the specific steps for constructing the longitudinal thermal insulation barrier in step IV are as follows:

[0024] S4.1: Select a preset number of insulation pipes, outer steel pipes and second bolts, and measure the actual length and diameter of the exposed section of each round steel pipe. Then check whether the specifications of each insulation pipe and each outer steel pipe are compatible with the diameter of the exposed section of each round steel pipe.

[0025] S4.2: Cut each insulation pipe according to the actual length of the exposed section of each round steel pipe, then align each insulation pipe with the exposed section of each round steel pipe and gently insert it. During the insertion process, keep each insulation pipe coaxial with each round steel pipe. After each insulation pipe is in place, check its fit with each round steel pipe.

[0026] S4.3: Cut each outer steel pipe according to the length of the exposed section of each round steel pipe, then use a hoist to vertically lift each outer steel pipe, control the axis of each outer steel pipe to coincide with the axis of each insulation pipe, put each outer steel pipe on the outside of each insulation pipe, and then fasten each outer steel pipe to each flange with the second bolt.

[0027] As a further aspect of the present invention, the specific steps for testing the entire structure using specialized equipment to perform connection quality testing, thermal insulation performance testing, and anchoring and load-bearing capacity testing in step V are as follows:

[0028] S5.1: Use a torque wrench to test the torque value of each first bolt and each second bolt according to the random sampling principle, and compare the torque value of each first bolt and each second bolt with the preset torque value. If the torque value of any first bolt or second bolt exceeds the deviation range, it is necessary to tighten it again and re-inspect. After that, check whether each insulation pipe and each outer steel pipe is damaged or displaced.

[0029] S5.2: Use an infrared thermometer to measure the temperature of the exposed section of each round steel pipe, the outer wall of each outer steel pipe, and the top of each main anchor and auxiliary anchor. Apply a simulated heat source to the top of each steel foundation and record the temperature of the exposed section of each round steel pipe, the outer wall of each outer steel pipe, and the top of each main anchor and auxiliary anchor after 1 hour. If the temperature at any point is within the preset range, it indicates that the heat has not been conducted longitudinally along the round steel pipe to the anchor and the frozen soil area.

[0030] S5.3: Record the temperature changes in the surrounding permafrost area to verify the insulation system's ability to control short-term temperature fluctuations. Set the number of data collections per month and monitor continuously for one year. If the annual temperature fluctuation is ≤0.3℃ / year, it indicates that the insulation layer thickness and sealing effect meet the expected requirements. Otherwise, an optimization plan will be developed.

[0031] S5.4: The slow-speed sustained load method is used to apply the load by using an anchor pull-out tester. Each load level is 10% of the set pull-out bearing capacity. Each load level is maintained for 1 hour after application. The pull-out amount of each main anchor and each auxiliary anchor is recorded. When the load reaches 1.5 times the design pull-out bearing capacity, if the pull-out amount of each main anchor and each auxiliary anchor does not exceed the preset range and there is no obvious plastic deformation, the pull-out bearing capacity of each main anchor and each auxiliary anchor is deemed to be qualified. Otherwise, it is deemed unqualified, and the corresponding main anchor and each auxiliary anchor are reworked.

[0032] S5.5: Tightly attach the shear bearing capacity testing device and each main anchor rod and each auxiliary anchor rod, and apply load in stages of 10% of the preset shear bearing capacity, maintaining each load for 30 minutes. Record the horizontal displacement of each main anchor rod and each auxiliary anchor rod. When the load reaches 1.2 times the design shear bearing capacity, if the horizontal displacement of each main anchor rod or each auxiliary anchor rod is outside the preset range and there are no obvious signs of damage, the shear bearing capacity is deemed qualified. Otherwise, the welding strength of each anchor plate to each main anchor rod and each auxiliary anchor rod needs to be checked.

[0033] S5.6: Apply horizontal loads to the foundation using ice thrust simulation loading equipment, and load in 5 levels according to the preset load size. Then monitor the horizontal displacement and vibration amplitude of the steel bearing platform, and monitor the stress distribution of the entire structure. If the stress distribution of the entire structure exceeds the preset range, it is determined to be non-compliant. Adjust the anchor group layout or strengthen the elastic buffer device, and retest until it is qualified.

[0034] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0035] According to the engineering design drawings, the preset installation points of each main anchor rod are marked in the construction area, and each auxiliary anchor rod is distributed in a triangular array around each main anchor rod, with a spacing of 1.5 to 2 times the diameter of each main anchor rod. Then, the preset installation points of each auxiliary anchor rod are marked synchronously. At the same time, anchor plates are welded at the lower parts of each main anchor rod and each auxiliary anchor rod. Each main anchor rod with an anchor plate is vertically or implanted at a set inclination angle into the points. After each auxiliary anchor rod is adjusted to the corresponding angle according to the angle of each main anchor rod, it is implanted. Then, the welding positions of circular steel pipes are marked at the bottom of each steel bearing platform. After welding, each steel bearing platform is hoisted above each main anchor rod by a lifting device, and the levelness and plane position of each steel bearing platform are adjusted in real time to align the lower ends of each circular steel pipe with the tops of each main anchor rod and each auxiliary anchor rod. Then, a preset number of flange plates, wear-resistant backing plates, extruded polystyrene board insulation boards, and first bolts are stacked and assembled at the lower ends of each circular steel pipe and the tops of each main anchor rod and each auxiliary anchor rod. Then, each first bolt is tightened in stages to construct a transverse insulation barrier. The lengths and diameters of the exposed sections of each circular steel pipe are measured, and each insulation pipe and each outer sleeve steel pipe are cut according to the actual lengths of the exposed sections of each circular steel pipe. Each insulation pipe is coaxially sleeved on the exposed section of each circular steel pipe and the fit is checked. A lifting hoist is used to vertically lift each outer sleeve steel pipe and sleeve it after its axis coincides with that of each insulation pipe. Each outer sleeve steel pipe is fastened to each flange plate through second bolts. Subsequently, the torques of the first bolts and the second bolts are sampled and detected. If they exceed the deviation range, they need to be re-fastened and re-inspected. The states of each insulation pipe and each outer sleeve steel pipe are further checked, and the temperature of the corresponding parts is measured with an infrared thermometer. A simulated heat source is added for 1 hour to verify that the heat is not longitudinally conducted. At the same time, the short-term temperature change in the frozen soil area is monitored. Data is collected monthly for 1 year in the long term. If the annual fluctuation is ≤0.3°C, it is qualified. The anchor rod pullout tester is used to load to 1.5 times the design pullout force. If the pullout amount is qualified and there is no plastic deformation, the pullout resistance meets the standard. The shear resistance is loaded to 1.2 times the design value. If the displacement is qualified and there is no damage, the shear resistance is qualified. The ice thrust device is used to load in 5 levels, and the displacements, vibrations, and structural stresses of each steel bearing platform are monitored. If it exceeds the preset value, the anchor group or buffer device is adjusted until it is qualified. It can effectively resist the complex loads in the ice area, eliminate the risk of thaw settlement, improve the bearing capacity of the foundation, and at the same time improve the construction safety and reliability, providing an efficient and reliable solution for energy projects in ice areas and frozen soil areas. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The drawings are used to provide a further understanding of the present invention and constitute a part of the specification. They are used together with the embodiments of the present invention to explain the present invention and do not constitute a limitation to the present invention.

[0037] Figure 1 It is a flow block diagram of the spiral anchor group composite foundation and construction method for double protection in ice areas proposed by the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS ​​​​​​The construction method of a composite foundation with dual protection for helical anchor groups in icy areas is as follows:

[0040] The installation positions of each main anchor and each auxiliary anchor are determined according to the engineering design drawings, and each main anchor is implanted into the foundation vertically or at a set angle.

[0041] Specifically, according to the engineering design drawings, the preset installation points of each main anchor rod are marked in the construction area, and each auxiliary anchor rod is distributed in a triangular array around each main anchor rod, with the distance between each auxiliary anchor rod and each main anchor rod being 1.5 to 2 times the diameter of each main anchor rod. The preset installation points of each auxiliary anchor rod are marked around each main anchor rod. Anchor plates are welded to the lower part of each main anchor rod and each auxiliary anchor rod, and the blades of each anchor plate are perpendicular to the axis of the corresponding main anchor rod and each auxiliary anchor rod. Then, each main anchor rod with the welded anchor plate is inserted into the preset installation point vertically or at a set angle. The verticality or angle deviation of each auxiliary anchor rod is adjusted according to the angle of insertion of each main anchor rod. Finally, each auxiliary anchor rod is inserted into the preset installation point with the corresponding verticality or angle deviation.

[0042] Select the corresponding number of steel bearing platforms for each main anchor rod, and weld round steel pipes at the preset positions of each steel bearing platform. Then, adjust the levelness and planar position of each steel bearing platform in real time.

[0043] Specifically, based on the engineering design drawings, select the number of steel bearing platforms corresponding to each main anchor rod, and mark the welding positions of the round steel pipes on the bottom of each steel bearing platform. The number and position of each round steel pipe correspond one-to-one with each main anchor rod and each auxiliary anchor rod. Weld the round steel pipes at the marked welding positions, and then use lifting equipment to hoist each steel bearing platform above each main anchor rod. Adjust the level and plane position of each steel bearing platform in real time so that the lower end of each round steel pipe is aligned with the top of each main anchor rod and each auxiliary anchor rod, and the deviation is within the preset range.

[0044] Example 2

[0045] Reference Figure 1 The construction method of a composite foundation with dual protection for helical anchor groups in icy areas is as follows:

[0046] The flanges, gaskets, and insulation boards are stacked and assembled in a preset installation sequence to form a transverse thermal insulation barrier.

[0047] Specifically, a predetermined number of flanges, gaskets, insulation plates, and first bolts are selected, and according to a predetermined installation sequence, each flange, gasket, and insulation plate is stacked and assembled at the lower end of each round steel pipe and the top of each main anchor rod and each auxiliary anchor rod. Among them, the insulation plate is made of extruded polystyrene board, and the gasket is made of wear-resistant steel. Each first bolt is inserted through the reserved holes of each flange, gasket, and insulation plate, and each first bolt is tightened by predetermined graded pre-tightening. Then, the bolt hole gaps of the first bolts are filled with silicone rubber sealant to construct a transverse thermal insulation barrier.

[0048] Select the corresponding insulation pipe and install it on the exposed section of each round steel pipe, and then select the corresponding outer steel pipe and install it on the outside of each insulation pipe to construct a longitudinal insulation barrier.

[0049] Specifically, select a predetermined number of insulation pipes, outer steel pipes, and second bolts, and measure the actual length and diameter of the exposed section of each round steel pipe. Then check whether the specifications of each insulation pipe and each outer steel pipe are compatible with the diameter of the exposed section of each round steel pipe. Cut each insulation pipe according to the actual length of the exposed section of each round steel pipe, then align each insulation pipe with the exposed section of each round steel pipe and gently insert it. During the insertion process, keep each insulation pipe and each round steel pipe coaxial. After each insulation pipe is in place, check its fit with each round steel pipe. Cut each outer steel pipe according to the length of the exposed section of each round steel pipe, then use a hoist to vertically lift each outer steel pipe, controlling the axis of each outer steel pipe to coincide with the axis of each insulation pipe. Insert each outer steel pipe onto the outside of each insulation pipe, and then fasten each outer steel pipe to each flange with the second bolt.

[0050] After construction is completed, professional equipment is used to test the entire structure for connection quality inspection, thermal insulation performance test, and anchoring and load resistance test.

[0051] Specifically, torque wrenches were used to randomly sample and measure the torque values ​​of each first and second bolt. These values ​​were then compared to preset torque values. If the torque value of any first or second bolt exceeded the deviation range, it needed to be retightened and re-inspected. Afterward, the insulation pipes and outer steel pipes were checked for damage or displacement. Infrared thermometers were used to measure the temperature of the exposed sections of each round steel pipe, the outer walls of each outer steel pipe, and the tops of each main and auxiliary anchor rod. A simulated heat source was applied to the top of each steel foundation for 1 hour, and the temperatures of the exposed sections of each round steel pipe and the outer walls of each outer steel pipe were recorded. The temperature of the wall, as well as the tops of each main anchor and auxiliary anchor, is recorded. If the temperature at any point is within the preset range, it indicates that heat has not been conducted longitudinally along the circular steel pipe to the anchor and frozen soil area. Temperature changes in the surrounding frozen soil area are recorded to verify the insulation system's ability to control short-term temperature fluctuations. Monthly data collection is set, and monitoring continues for one year. If the annual temperature fluctuation is ≤0.3℃ / year, it indicates that the insulation layer thickness and sealing effect meet the expected requirements; otherwise, an optimization plan is developed. A slow-maintaining load method is used with an anchor pull-out tester, with each load level being 10% of the set pull-out bearing capacity. After each load level is applied, a maintenance load is applied. Hold the load for 1 hour and record the pull-out of each main anchor and auxiliary anchor. When the load reaches 1.5 times the design pull-out bearing capacity, if the pull-out of each main anchor and auxiliary anchor does not exceed the preset range and there is no obvious plastic deformation, the pull-out bearing capacity of each main anchor and auxiliary anchor is deemed qualified; otherwise, it is deemed unqualified, and the corresponding main anchor and auxiliary anchor are reworked. The shear bearing capacity testing device is then tightly fitted to each main anchor and auxiliary anchor, and the load is applied in stages of 10% of the preset shear bearing capacity, with each load maintained for 30 minutes. The horizontal displacement of each main anchor and auxiliary anchor is recorded. When the load reaches 1.5 times the design shear bearing capacity... If the horizontal displacement of each main anchor or auxiliary anchor exceeds the preset range when the load is 1.2 times the bearing capacity, and there are no obvious signs of damage, the shear bearing capacity is deemed qualified. Otherwise, the welding strength of each anchor plate to each main anchor and each auxiliary anchor needs to be checked. A horizontal load is applied to the foundation using an ice thrust simulation loading device, and the load is applied in 5 levels according to the preset load size. The horizontal displacement and vibration amplitude of the steel foundation are then monitored, and the stress distribution of the entire structure is monitored. If the stress distribution of the entire structure exceeds the preset range, it is deemed unqualified. The anchor group layout is adjusted or the elastic buffer device is strengthened, and the test is repeated until it is qualified.

Claims

1. A composite foundation with helical anchor groups and construction method for dual protection in icy areas, characterized in that, The specific steps of this construction method are as follows: Ⅰ: Determine the installation positions of each main anchor and each auxiliary anchor according to the engineering design drawings, and implant each main anchor vertically or at a set angle into the foundation; II: Select the corresponding number of steel bearing platforms for each main anchor rod, and weld round steel pipes at the preset positions of each steel bearing platform, and then adjust the levelness and plane position of each steel bearing platform in real time; III: Assemble all flanges, gaskets, and insulation boards in the preset installation sequence to form a transverse thermal insulation barrier; IV: Select the corresponding thermal insulation pipe and install it on the exposed section of each round steel pipe, and then select the corresponding outer steel pipe and install it on the outside of each thermal insulation pipe to construct a longitudinal thermal insulation barrier; V: After construction is completed, professional equipment is used to test the entire structure for connection quality inspection, thermal insulation performance test, and anchoring and load resistance test.

2. The composite foundation and construction method for dual protection in ice-affected areas using spiral anchor groups as described in claim 1, characterized in that, The specific steps for inserting each main anchor rod into the foundation vertically or at a predetermined angle, as described in step I, are as follows: S1.1: Mark the preset installation points of each main anchor in the construction area according to the engineering design drawings, and distribute each auxiliary anchor in a triangular array around each main anchor, with the distance between each auxiliary anchor and each main anchor being 1.5 to 2 times the diameter of each main anchor. Mark the preset installation points of each auxiliary anchor around each main anchor. S1.2: Weld anchor plates to the lower part of each main anchor and each auxiliary anchor, and at the same time, the blades of each anchor plate are perpendicular to the axis of each corresponding main anchor and each auxiliary anchor. Then, insert each main anchor with the anchor plate welded on it into the preset installation point at a vertical angle or a set angle. S1.3: Adjust the verticality or tilt angle deviation of each auxiliary anchor rod according to the angle at which each main anchor rod is inserted, and then insert each auxiliary anchor rod into the preset installation point with the corresponding verticality or tilt angle deviation.

3. The composite foundation and construction method for dual protection in ice-affected areas using spiral anchor groups as described in claim 2, characterized in that, The specific steps for adjusting the levelness and planar position of the steel foundation in real time as described in step II are as follows: S2.1: Select the number of steel bearing platforms corresponding to each main anchor rod according to the engineering design drawings, and mark the welding position of the round steel pipe at the bottom of each steel bearing platform. The number and position of each round steel pipe correspond one-to-one with each main anchor rod and each auxiliary anchor rod. S2.2: Weld round steel pipes at the marked welding positions, and then use lifting equipment to hoist each steel bearing platform above each main anchor rod. Adjust the level and plane position of each steel bearing platform in real time so that the lower end of each round steel pipe is aligned with the top of each main anchor rod and each auxiliary anchor rod, and the deviation is within the preset range.

4. The composite foundation and construction method for dual protection in ice-affected areas using spiral anchor groups as described in claim 3, characterized in that, The specific steps for constructing the transverse thermal barrier described in step III are as follows: S3.1: Select a preset number of flanges, gaskets, insulation plates and first bolts, and according to the preset installation sequence, stack each flange, gasket and insulation plate at the lower end of each round steel pipe and the top of each main anchor and auxiliary anchor. Among them, the insulation plate is made of extruded polystyrene board and the gasket is made of wear-resistant steel. S3.2: Insert each first bolt through the reserved holes of each flange, each gasket and each insulation plate, and tighten each first bolt by pre-setting graded pre-tightening. Then fill the bolt hole gaps of the first bolts with silicone rubber sealant to construct a transverse thermal insulation barrier.

5. The composite foundation and construction method for dual protection in ice-affected areas using spiral anchor groups as described in claim 2, characterized in that, The specific steps for constructing the longitudinal thermal barrier described in step IV are as follows: S4.1: Select a preset number of insulation pipes, outer steel pipes and second bolts, and measure the actual length and diameter of the exposed section of each round steel pipe. Then check whether the specifications of each insulation pipe and each outer steel pipe are compatible with the diameter of the exposed section of each round steel pipe. S4.2: Cut each insulation pipe according to the actual length of the exposed section of each round steel pipe, then align each insulation pipe with the exposed section of each round steel pipe and gently insert it. During the insertion process, keep each insulation pipe coaxial with each round steel pipe. After each insulation pipe is in place, check its fit with each round steel pipe. S4.3: Cut each outer steel pipe according to the length of the exposed section of each round steel pipe, then use a hoist to vertically lift each outer steel pipe, control the axis of each outer steel pipe to coincide with the axis of each insulation pipe, put each outer steel pipe on the outside of each insulation pipe, and then fasten each outer steel pipe to each flange with the second bolt.

6. The composite foundation and construction method for dual protection in ice-affected areas using spiral anchor groups as described in claim 4, characterized in that, The specific steps for testing the entire structure using specialized equipment in step V to inspect connection quality, thermal insulation performance, and anchorage and load-bearing capacity are as follows: S5.1: Use a torque wrench to test the torque value of each first bolt and each second bolt according to the random sampling principle, and compare the torque value of each first bolt and each second bolt with the preset torque value. If the torque value of any first bolt or second bolt exceeds the deviation range, it is necessary to tighten it again and re-inspect. After that, check whether each insulation pipe and each outer steel pipe is damaged or displaced. S5.2: Use an infrared thermometer to measure the temperature of the exposed section of each round steel pipe, the outer wall of each outer steel pipe, and the top of each main anchor and auxiliary anchor. Apply a simulated heat source to the top of each steel foundation and record the temperature of the exposed section of each round steel pipe, the outer wall of each outer steel pipe, and the top of each main anchor and auxiliary anchor after 1 hour. If the temperature at any point is within the preset range, it indicates that the heat has not been conducted longitudinally along the round steel pipe to the anchor and the frozen soil area. S5.3: Record the temperature changes in the surrounding permafrost area to verify the insulation system's ability to control short-term temperature fluctuations. Set the number of data collections per month and monitor continuously for one year. If the annual temperature fluctuation is ≤0.3℃ / year, it indicates that the insulation layer thickness and sealing effect meet the expected requirements. Otherwise, an optimization plan will be developed. S5.4: The slow-speed sustained load method is used to apply the load by using an anchor pull-out tester. Each load level is 10% of the set pull-out bearing capacity. Each load level is maintained for 1 hour after application. The pull-out amount of each main anchor and each auxiliary anchor is recorded. When the load reaches 1.5 times the design pull-out bearing capacity, if the pull-out amount of each main anchor and each auxiliary anchor does not exceed the preset range and there is no obvious plastic deformation, the pull-out bearing capacity of each main anchor and each auxiliary anchor is deemed to be qualified. Otherwise, it is deemed unqualified, and the corresponding main anchor and each auxiliary anchor are reworked. S5.5: Tightly attach the shear bearing capacity testing device and each main anchor rod and each auxiliary anchor rod, and apply load in stages of 10% of the preset shear bearing capacity, maintaining each load for 30 minutes. Record the horizontal displacement of each main anchor rod and each auxiliary anchor rod. When the load reaches 1.2 times the design shear bearing capacity, if the horizontal displacement of each main anchor rod or each auxiliary anchor rod is outside the preset range and there are no obvious signs of damage, the shear bearing capacity is deemed qualified. Otherwise, the welding strength of each anchor plate to each main anchor rod and each auxiliary anchor rod needs to be checked. S5.6: Apply horizontal loads to the foundation using ice thrust simulation loading equipment, and load in 5 levels according to the preset load size. Then monitor the horizontal displacement and vibration amplitude of the steel bearing platform, and monitor the stress distribution of the entire structure. If the stress distribution of the entire structure exceeds the preset range, it is determined to be non-compliant. Adjust the anchor group layout or strengthen the elastic buffer device, and retest until it is qualified.

Images