Anti-freezing construction method for photovoltaic foundation and support assembly in severe cold area

Abstract

The invention belongs to the field of construction in severe cold areas, and particularly relates to an anti-freezing construction method for a photovoltaic foundation and a support assembly in severe cold areas, which comprises the following steps: step 1, constructing an anti-freezing and anti-thawing foundation; a concrete pipe pile is adopted as a foundation, the length of a pile body is selected according to characteristics of a frost heaving soil area, and the pile body penetrates through a seasonal frozen soil layer to reach a stable bearing stratum; secondly, auxiliary excavation and pile sinking are conducted through frozen soil; a hydraulic hammer is matched with heating equipment to destroy the frozen soil structure, and then a rotary drilling rig is used for hole guiding; step 3, constructing an anti-freezing cable trench; a cable trench is excavated, a heat preservation layer and an anti-seepage film are laid at the trench bottom, a drainage slope is set, and layered backfilling and tamping are carried out after a cold-resistant cable is laid; 4, mounting the low-temperature adaptive bracket and the assembly; selecting a low-temperature-resistant photovoltaic module and a cold-resistant cable; the support is fixed to a pipe pile foundation through the hoop device. Step 5, welding-free grounding construction is carried out; grounding grid laying is carried out by adopting an alloy cold pressing connection process, and a traditional welding process is replaced.

Description

Technical Field

[0001] This invention relates to the field of construction in frigid regions, specifically to a method for anti-freezing construction of photovoltaic foundations and support components in frigid regions. Background Technology

[0002] Against the backdrop of a global energy transition towards cleaner energy, centralized photovoltaic (PV) power generation has become crucial for renewable energy development due to its scale advantages. However, in extremely cold regions, such as the Zhangbei Dam area where temperatures can reach as low as -35°C and permafrost depths can reach several meters, numerous challenges arise for on-site PV construction. Existing technologies suffer from the following deficiencies: ① Foundation construction defects: Traditional shallow foundations are susceptible to frost heave, leading to foundation uplift and damage; concrete sets for longer periods and gains strength more slowly at low temperatures, and there is a lack of targeted antifreeze materials and curing measures, making it difficult to guarantee the quality of foundation construction. ② Permafrost treatment defects: Permafrost excavation often uses conventional mechanical crushing, which easily produces large frozen blocks, and if the foundation is not constructed promptly after excavation, secondary freezing can easily occur; cable trenches and pipe trenches lack effective insulation and drainage measures, and freeze-thaw cycles can easily cause structural damage. ③ Equipment and material compatibility defects: Ordinary PV modules and cables are prone to embrittlement and failure at low temperatures; the support structure is insufficiently designed to withstand wind loads and frost heave, making it difficult to withstand wind and snow disasters; grounding construction uses traditional flat steel welding technology, resulting in unstable welding quality in winter and a tendency for connections to loosen. ④ Construction organization defects: The construction period was not staggered according to the "thaw-freeze" cycle of frozen soil, and most of the winter construction was in the "winter rest period", resulting in serious delays in the construction period; there was insufficient coordination among multiple disciplines, the process was chaotic and overlapping, and the frozen soil excavation area was not backfilled in time after construction, which aggravated the risk of frost heave.

[0003] Therefore, in order to solve the above-mentioned problems, a method for antifreeze construction of photovoltaic foundations and support components in extremely cold regions is proposed. Summary of the Invention

[0004] This invention addresses the aforementioned problems by specifically designing a freeze-thaw resistant construction method for photovoltaic (PV) foundations and support components in frigid regions. It provides freeze-thaw resistant foundation design and construction schemes to ensure foundation penetration through the frozen soil layer, improve the freeze-thaw resistance and curing effect of concrete, and guarantee foundation stability. It optimizes frozen soil excavation and protection processes, improving excavation efficiency, avoiding secondary freezing, and reducing damage to trench structures from freeze-thaw cycles. It optimizes support structure and grounding processes, enhancing the low-temperature adaptability and snow and wind resistance of equipment and materials. Finally, it optimizes the PV construction process in frigid regions, enabling staggered construction schedules and multi-disciplinary collaboration, shortening the construction cycle, and reducing costs.

[0005] To achieve the above objectives, the present invention provides a method for anti-freezing construction of photovoltaic foundations and support components in extremely cold regions, comprising the following steps: Step 1: Construction of freeze-thaw resistant foundation; Concrete pipe piles are used as the foundation, with the pile length selected according to the characteristics of the frost-susceptible soil area, and penetrating the seasonally frozen soil layer to reach the stable bearing layer; Antifreeze agents and air-entraining agents are added to the foundation concrete, and electric heat tracing is used for curing; Asphalt-based drag-reducing coating or PVC isolation sleeve is applied to the outer surface of the pipe pile at the depth of the seasonally frozen soil layer to reduce the tangential frost heave bond force of the frozen soil layer on the pile body; Step 2: Frozen soil assisted excavation and pile driving; a hydraulic hammer and heating equipment are used to break the frozen soil structure, followed by a rotary drilling rig to drill a hole, and then a pile driver is immediately organized to drive the pile; after the pile driving is completed, antifreeze thixotropic mud is immediately injected into the annular gap between the pile body and the drill hole to prevent surface water from seeping into the gap and forming an ice lens. Step 3: Construction of antifreeze cable trench; excavate cable trench, lay insulation layer and seepage-proof membrane at the bottom of the trench, set drainage slope, lay cold-resistant cable, and then backfill and compact in layers. Step 4: Install the low-temperature adaptable bracket and components; fix them to the pipe pile foundation using clamps; add wind-resistant connection devices between the bracket and components; Step 5: Weld-free grounding construction; the grounding grid is laid using alloy cold-pressing connection technology, replacing the traditional welding process.

[0006] Furthermore, in step one: the concrete pipe pile penetrates the seasonally frozen soil layer to a depth of at least 2m; the frost resistance grade of the foundation concrete is not lower than F300; a 300mm thick crushed stone cushion layer and a 50mm thick extruded polystyrene insulation board are laid from bottom to top at the foundation; during the electric heat tracing curing process, a phase change energy storage insulation blanket is covered on the concrete surface to utilize the latent heat released by the phase change material to maintain a constant temperature on the concrete surface, reduce the energy consumption of electric heating, and prevent microcracks caused by drastic temperature fluctuations.

[0007] Furthermore, in step two, the specific process flow is as follows: a hydraulic hammer is used to break the frozen soil, and a warming gun is used to heat the surface of the frozen soil layer to a softening depth ≥100mm; a rotary drilling rig is used to drill a pilot hole, the pilot hole depth penetrating the thickness of the frozen soil layer; pile driving is carried out immediately after the pilot hole is completed; the injection height of the antifreeze thixotropic mud should be 200mm lower than the natural ground surface, and graded sand and gravel should be backfilled on top to seal the opening and prevent the mud from overflowing and causing surface pollution.

[0008] Furthermore, in step three, the specific parameters for the construction of the antifreeze cable trench are as follows: excavation depth ≥ 1.2m; a 100mm thick polyurethane foam insulation layer is laid at the bottom of the trench; a drainage slope of ≥ 3% is set at the bottom of the trench; a 1.5mm thick impermeable membrane is laid on both sides of the bottom of the trench; after the cable is laid, the trench is filled with graded sand and gravel, and the top is covered with 300mm thick plain soil and compacted in layers; in the backfill soil layer of the cable trench, a ventilated drainage valve is set every 10 meters to drain the condensate water generated in the trench due to the ground temperature difference, and to prevent it from accumulating, freezing and squeezing the cable.

[0009] Furthermore, in step four: the support structure is made of Q420-B steel, and low-temperature resistant photovoltaic modules and cold-resistant cables are selected; angle steel is added as a diagonal brace; the support structure is bolted, and the "low-temperature torque compensation method" is used when installing the bolts. The tightening torque is corrected by referring to the metal shrinkage coefficient table according to the ambient temperature on the day of construction, and low-temperature resistant anti-loosening conductive grease is applied to the bolt threads; angle steel is added as a diagonal brace; the clamp device is designed to be adjustable, used to adjust the installation elevation of the components when there is a deviation in the foundation position or elevation; the clamp device is lined with a low-temperature resistant rubber damping pad to absorb the small displacements caused by the pipe pile and the support under different thermal expansion coefficients, and to prevent stress concentration and breakage at the hard connection.

[0010] Furthermore, in step five: ACR alloy connectors are used for the connection between component supports and the grounding grid, and the connection is made by cold pressing; ACR alloy connector grounding rings are laid 2m around the transformer, and vertical grounding electrodes are set up to penetrate 2m below the depth of the frozen soil.

[0011] Furthermore, it also includes full-cycle monitoring and dynamic adjustment steps: temperature sensors and displacement sensors are pre-embedded in the support foundation and the bottom of the transformer; a dynamic operation and maintenance model based on frost heave data is constructed. When the displacement sensor data indicates that the foundation has uneven settlement or lifting by more than 3mm, the angle of the photovoltaic module is reversely compensated and adjusted through the adjustable clamp device on the support to ensure the overall flatness of the photovoltaic module array.

[0012] Furthermore, the clamping device includes: an arc-shaped plate, a reinforcing rib, a fixing bolt, and a pad. There are two arc-shaped plates, one of which has the reinforcing rib on its upper part, and the other arc-shaped plate is connected to the arc-shaped plate with the reinforcing rib through a pad and a fixing bolt. The two arc-shaped plates are clamped on the concrete pipe pile.

[0013] Furthermore, in the full-cycle monitoring step, the transmission and processing of sensor detection data are as follows: the temperature sensor and displacement sensor are connected to a wireless data acquisition terminal set up on site via signal lines. The wireless data acquisition terminal establishes a communication connection with the remote monitoring server through a mobile communication network and uploads the collected data packets in encryption. In addition to the base temperature and displacement, the detection data also includes water and heat migration parameters within the frozen soil layer. For this purpose, soil moisture sensors and pore water pressure gauges are added in soil layers at different depths around the foundation. The remote monitoring server calculates the unfrozen water content of the frozen soil layer based on the uploaded soil moisture content change gradient and pore water pressure dissipation data to determine the incubation period of frost heave.

[0014] The full-cycle monitoring process also includes stress and attitude monitoring of the foundation and support structure: fiber optic strain sensors are pre-installed on the main reinforcement bars of the prestressed high-strength concrete pipe pile's steel cage. These fiber optic strain sensors are used to detect the axial tensile stress and bending stress data of the pile body under the action of frost heave force in frozen soil. MEMS dual-axis tilt sensors are installed on the top of the photovoltaic support column to detect the tilt angle data of the photovoltaic support relative to the horizontal plane along the X and Y axes. After receiving the above data, the remote monitoring server compares the real-time tensile stress data with a preset concrete crack resistance threshold and compares the tilt angle data with a preset angle deviation threshold. When any data exceeds the threshold, the server automatically generates an alarm command containing the fault pile number location information and sends it to the mobile terminal of the maintenance personnel.

[0015] In summary, the frost-resistant construction method for photovoltaic foundations and support components in frigid regions of the present invention has the following advantages and beneficial technical effects: 1. This invention utilizes prestressed high-strength concrete pipe piles to penetrate seasonally frozen soil to the stable bearing layer, anchoring the foundation using pile end resistance. Furthermore, the added drag-reducing coating or PVC isolation sleeve effectively severs the tangential frost heave bond between the frozen soil and the pile body. Combined with antifreeze thixotropic mud filling the pile hole gaps, it prevents surface water infiltration and the formation of ice lenses, thus eliminating the risk of "freeze-pull-out." In addition, the electric heat tracing method combined with a phase change energy storage insulation blanket not only ensures the hydration reaction and strength increase of the concrete at low temperatures but also utilizes the latent heat of phase change to reduce micro-cracks caused by temperature fluctuations, keeping the foundation's frost heave deformation at an extremely low level (e.g., ≤3mm), significantly extending the foundation's service life. 2. This invention employs a combined thawing process of hydraulic hammer crushing and warming gun heating, solving the problems of difficult and inefficient excavation of frozen soil. Through the compact process of "immediately driving piles after drilling," combined with the use of antifreeze thixotropic mud, secondary freezing of the borehole walls is effectively prevented. This complete low-temperature construction scheme transforms the traditional "winter break" into an effective construction period, expected to shorten the construction period by more than 30%, enabling staggered construction and early grid connection of photovoltaic projects. 3. Constructing a full-cycle intelligent sensing system to achieve a shift from "passive emergency repair" to "proactive early warning." Unlike traditional manual inspections, this invention establishes a multi-dimensional sensor network encompassing temperature, displacement, stress, attitude, and hydrothermal migration (soil moisture / water pressure). This system can not only capture minute displacements and tilts of the foundation in real time, but also predict frost heave risks and locate hidden damage by monitoring the unfrozen water content of the soil and the internal stress of the pile. Through data analysis and automatic alarms from remote terminals, maintenance personnel can promptly intervene, greatly reducing the difficulty and cost of operation and maintenance throughout the entire lifecycle of the photovoltaic power station. Attached Figure Description

[0016] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which: Figure 1 This is a schematic diagram of the bracket and components of the present invention. Figure 2 This is a schematic diagram of the structure of the bracket and pipe pile foundation clamp connection device of the present invention; Figure 3 This is a schematic diagram illustrating the connection effect between the ACR alloy connector of the present invention and the photovoltaic bracket; Figure 4 This is a schematic diagram of the structure of the wind-resistant connection of the photovoltaic panel in this invention; Figure 5 This is a schematic diagram of the freeze-thaw resistant basic structure of the present invention.

[0017] The reference numerals in the attached figures are: 1-Clamping device; 11-Arc-shaped plate; 12-Reinforcing rib; 13-Fixing bolt; 14-Plate; 2-Support frame; 21-Photovoltaic panel assembly; 3-Concrete pipe pile; 4-Extruded polystyrene insulation board; 5-Crushed stone cushion layer; 6-Frozen soil layer; 7-ACR alloy connector; Detailed Implementation To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of the embodiments of this invention will be described in more detail below with reference to the accompanying drawings. In the drawings, the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout; the described embodiments are some embodiments of this invention, but not all embodiments; the embodiments and directional terms described below with reference to the accompanying drawings are exemplary and intended to explain this invention, and should not be construed as limiting this invention; all other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention. The parts and equipment all adopt conventional models in the prior art, and the circuit connections adopt conventional connection methods in the prior art, which will not be described in detail here. Contents not described in detail in this specification belong to the prior art known to those skilled in the art. The embodiments of this invention will be described in detail below with reference to the accompanying drawings: like Figure 4 and Figure 5 As shown, it includes the following steps: Step 1: Construction of the freeze-thaw resistant foundation; Concrete pipe piles 3 are used as the foundation, and the length of the pile body is selected according to the characteristics of the frost-susceptible soil area, and it penetrates the seasonally frozen soil layer 6 to reach the stable bearing layer; Antifreeze agent and air-entraining agent are added to the foundation concrete, and electric heat tracing is used for curing; Asphalt-based drag-reducing coating or PVC isolation sleeve is applied to the outer surface of the pipe pile at the depth of the seasonally frozen soil layer to reduce the tangential frost-susceptibility bond force of the frozen soil layer 6 to the pile body; Step 2: Frozen soil assisted excavation and pile driving; a hydraulic hammer and heating equipment are used to break the frozen soil structure, followed by a rotary drilling rig to drill a hole, and then a pile driver is immediately organized to drive the pile; after the pile driving is completed, antifreeze thixotropic mud is immediately injected into the annular gap between the pile body and the drill hole to prevent surface water from seeping into the gap and forming an ice lens. Step 3: Construction of antifreeze cable trench; excavate cable trench, lay insulation layer and seepage-proof membrane at the bottom of the trench, set drainage slope, lay cold-resistant cable, and then backfill and compact in layers. Step 4: Install the low-temperature adapter bracket 2 and component 21; fix it to the pipe pile foundation using clamp device 1; add a wind-resistant connection device between bracket 2 and component 21; Step 5: Weld-free grounding construction; the grounding grid is laid using alloy cold-pressing connection technology, replacing the traditional welding process.

[0018] By using prestressed high-strength concrete pipe piles to penetrate the frozen soil layer to the bearing layer, and in conjunction with pile drag reduction and isolation measures, the mechanical transmission path between the frozen soil and the pile body is effectively cut off, transforming the frost heave destructive force into relative sliding of the soil around the pile. Simultaneously, antifreeze thixotropic mud is used to fill the gaps in the pile holes, blocking the path of surface water seeping down the pile body to form ice lenses, fundamentally eliminating the hidden danger of foundation frost pull-out and ensuring the long-term stability of the photovoltaic support foundation in frigid regions.

[0019] like Figure 5 As shown, in step one: the concrete pipe pile 3 penetrates the seasonally frozen soil layer 6 to a depth of at least 2m; the frost resistance grade of the foundation concrete is not lower than F300; a 300mm thick crushed stone cushion layer 5 and a 50mm thick extruded polystyrene insulation board 4 are laid from bottom to top at the foundation; during the electric heat tracing curing process, a phase change energy storage insulation blanket is covered on the concrete surface, utilizing the latent heat released by the phase change material to maintain a constant temperature on the concrete surface, reducing the energy consumption of electric heating and preventing micro-cracks caused by drastic temperature fluctuations. The crushed stone cushion layer and the extruded polystyrene insulation board form a foundation insulation layer, reducing heat exchange between the frozen soil layer and the ground. By using a phase change energy storage insulation blanket in conjunction with electric heat tracing, the latent heat release characteristics of the phase change material are utilized to provide a constant temperature curing environment for the concrete, reducing energy consumption while ensuring the microstructural density and frost resistance durability of the concrete at low temperatures.

[0020] like Figure 5As shown, in step two, the specific process flow is as follows: A hydraulic hammer is used to break up the frozen soil, and a warming gun is used to heat the surface of the frozen soil layer, softening it to a depth ≥100mm; a rotary drilling rig is used to drill a pilot hole, penetrating the thickness of the frozen soil layer; pile driving is carried out immediately after the pilot hole is completed; the injection height of the antifreeze thixotropic mud should be 200mm lower than the natural ground level, and graded sand and gravel should be backfilled on top to seal the hole and prevent mud overflow from causing surface pollution. The combined process of hydraulic breaking and local heating softening significantly reduces drilling resistance and improves hole formation efficiency. The compact process of injecting antifreeze thixotropic mud immediately after pilot hole drilling and driving the pile utilizes the thixotropic and non-freezing properties of the mud to support the hole wall and fill the gaps, preventing hole shrinkage and achieving flexible sealing around the pile, thus improving construction continuity. The combined process of hydraulic breaking and local heating softening significantly reduces drilling resistance and improves hole formation efficiency. The compact process of injecting antifreeze thixotropic mud immediately after drilling and then driving the pile utilizes the thixotropic and nonfreeze properties of the mud to support the borehole wall and fill the gaps, which not only prevents borehole shrinkage but also achieves a flexible seal around the pile, thus improving the continuity of construction.

[0021] like Figure 5 As shown, the specific parameters for the construction of the anti-freeze cable trench in step three are as follows: excavation depth ≥ 1.2m; a 100mm thick polyurethane foam insulation layer is laid at the bottom of the trench; a drainage slope of ≥ 3% is set at the bottom of the trench; a 1.5mm thick impermeable membrane is laid on both sides of the bottom of the trench; after the cable is laid, the trench is filled with graded sand and gravel, and the top is covered with 300mm thick plain soil and compacted in layers; in the backfill soil layer of the cable trench, a ventilated drainage valve is installed every 10 meters to drain the condensate water generated by the ground temperature difference in the trench, preventing it from accumulating, freezing, and squeezing the cable. The polyurethane insulation layer and the impermeable membrane form a heat insulation and waterproof barrier. In particular, the setting of the ventilated drainage valve establishes a microclimate regulation mechanism in the trench using the unidirectional conduction principle, which can timely drain the hot and humid gas generated by the geothermal factor, keep the environment in the trench dry, and significantly reduce the risk of the cold-resistant cable insulation layer cracking due to freezing and pressure.

[0022] like Figure 1 and Figure 5As shown, bracket 2 is made of Q420-B steel, and uses low-temperature resistant photovoltaic modules 21 and cold-resistant cables; angle steel is added as a diagonal brace; bracket 2 is bolted, and the "low-temperature torque compensation method" is used when installing the bolts. The tightening torque is corrected by referring to the metal shrinkage coefficient table based on the ambient temperature on the construction day, and low-temperature resistant anti-loosening conductive paste is applied to the bolt threads; angle steel is added as a diagonal brace; the clamp device 1 is designed to be adjustable to adjust the installation elevation of the components when there are deviations in the foundation position or elevation; the inner side of the clamp device 1 is lined with a low-temperature resistant rubber damping pad to absorb the small displacements caused by different thermal expansion coefficients between the pipe pile and the bracket, preventing stress concentration and fracture at the hard connection. The low-temperature torque compensation method eliminates the influence of temperature changes on the preload, preventing bolt breakage or loosening. The low-temperature resistant rubber damping pad forms an elastic buffer layer between the foundation and the bracket, effectively absorbing relative displacement and vibration energy, avoiding brittle fracture at the hard connection, and improving the fatigue life of the structure in low-temperature and strong-wind environments.

[0023] like Figure 3 As shown, in step five: ACR alloy connectors (7) are used for the connection between component supports and the grounding grid, and are connected by cold pressing; ACR alloy connector (7) grounding rings are laid 2m around the transformer, and vertical grounding electrodes are set up to penetrate 2m below the depth of the frozen soil. The cold pressing connection process of ACR alloy connectors uses physical mechanical interlocking instead of hot processing. The construction process is not affected by air temperature and wind speed, and the contact resistance of the connection point is stable and the corrosion resistance is strong, ensuring the electrical continuity and safety of the grounding system throughout its entire life cycle.

[0024] It also includes full-cycle monitoring and dynamic adjustment steps: temperature and displacement sensors are pre-embedded in the support foundation and at the bottom of the transformer; a dynamic operation and maintenance model based on frost heave data is constructed. When the displacement sensor data indicates that the foundation has experienced uneven settlement or heave exceeding 3mm, the angle of the photovoltaic modules is adjusted in reverse through the adjustable clamp device on the support to ensure the overall flatness of the photovoltaic module array. A closed loop from "monitoring" to "execution" is constructed. Once a small displacement within the allowable range of the foundation is detected, the posture of the support can be corrected through the adjustable clamp device to ensure that the photovoltaic module array always remains on the design plane, preventing physical damage to the modules caused by structural deformation.

[0025] like Figure 2 As shown, the clamping device 1 includes: an arc-shaped plate 11, a reinforcing rib 12, a fixing bolt 13, and a pad 14. There are two arc-shaped plates 11. One of the arc-shaped plates 11 has a reinforcing rib 12 on its upper part. The other arc-shaped plate 11 is connected to the arc-shaped plate 11 with the reinforcing rib 12 through the pad 14 and the fixing bolt 13. The two arc-shaped plates 11 are clamped on the concrete pipe pile 3.

[0026] In the full-cycle monitoring process, the transmission and processing of sensor data are as follows: Temperature and displacement sensors are connected to a wireless data acquisition terminal set up on-site via signal lines. The wireless data acquisition terminal establishes a communication connection with a remote monitoring server through a mobile communication network, encrypting and uploading the collected data packets. In addition to base temperature and displacement, the detection data also includes water and heat migration parameters within the permafrost layer. Therefore, soil moisture sensors and pore water pressure gauges are added to soil layers at different depths around the foundation. The remote monitoring server calculates the unfrozen water content in the permafrost layer based on the uploaded soil moisture content change gradient and pore water pressure dissipation data to determine the incubation period for frost heave. By monitoring the soil moisture gradient and pore water pressure, the migration path of water within the permafrost layer can be visualized. Before water accumulates into ice lenses and causes damage, an early warning can be issued via the remote server, providing a time window for intervention measures such as drainage and achieving source control of frost damage.

[0027] The full-cycle monitoring process also includes stress and attitude monitoring of the foundation and support structures: Fiber Bragg grating (FBG) strain sensors are pre-installed on the main reinforcement bars of the prestressed high-strength concrete pipe pile's steel cage. These FBG strain sensors detect axial tensile stress and bending stress data of the pile body under the action of frost heave force in frozen soil. MEMS dual-axis tilt sensors are installed on the top of the photovoltaic support column to detect the X-axis and Y-axis tilt angle data of the photovoltaic support relative to the horizontal plane. After receiving the above data, the remote monitoring server compares the real-time tensile stress data with a preset concrete crack resistance threshold and the tilt angle data with a preset angle deviation threshold. When either data exceeds the threshold, the server automatically generates an alarm command containing the fault pile number location information and sends it to the mobile terminal of the maintenance personnel. The FBG sensor can accurately capture stress changes inside the pile body, preventing the pipe pile from breaking before it is pulled out. The MEMS tilt sensor enables digital perception of the structural attitude. The combination of these two technologies enables quantitative assessment and precise positioning of the photovoltaic support system's health status, significantly improving the intelligent operation and maintenance level of the power station.

[0028] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for frost-resistant construction of photovoltaic foundations and support components in extremely cold regions, characterized in that, Includes the following steps: Step 1: Construction of freeze-thaw resistant foundation; Concrete pipe piles (3) are used as the foundation, the length of the pile body is selected according to the characteristics of the frost-susceptible soil area, and it penetrates the seasonally frozen soil layer (6) to reach the stable bearing layer; Antifreeze and air-entraining agent are added to the foundation concrete and cured by electric heat tracing; asphalt-based drag-reducing coating or PVC isolation sleeve is applied to the outer surface of the pipe pile at the depth of the seasonal frozen soil layer to reduce the tangential frost heave bond force of the frozen soil layer (6) on the pile body. Step 2: Frozen soil assisted excavation and pile driving; a hydraulic hammer and heating equipment are used to break the frozen soil structure, followed by a rotary drilling rig to drill a hole, and then a pile driver is immediately organized to drive the pile; after the pile driving is completed, antifreeze thixotropic mud is immediately injected into the annular gap between the pile body and the drill hole to prevent surface water from seeping into the gap and forming an ice lens. Step 3: Construction of antifreeze cable trench; excavate cable trench, lay insulation layer and seepage-proof membrane at the bottom of the trench, set drainage slope, lay cold-resistant cable, and then backfill and compact in layers. Step 4: Install the low-temperature adapter bracket (2) and component (21); fix it to the pipe pile foundation through the clamp device (1); add a wind-resistant connection device between the bracket (2) and component (21); Step 5: Weldless grounding construction; the grounding grid is laid using alloy cold pressing connection technology.

2. The method for frost-resistant construction of photovoltaic foundations and support components in frigid regions according to claim 1, characterized in that, In step one: the concrete pipe pile (3) penetrates the seasonally frozen soil layer (6) to a depth of at least 2m; the frost resistance grade of the foundation concrete is not lower than F300; a 300mm thick crushed stone cushion layer (5) and a 50mm thick extruded polystyrene insulation board (4) are laid from bottom to top at the foundation; during the electric heat tracing curing process, a phase change energy storage insulation blanket is covered on the concrete surface, and the latent heat released by the phase change material is used to maintain the constant temperature of the concrete surface, reduce the energy consumption of electric heating and prevent microcracks caused by drastic temperature fluctuations.

3. The method for frost-resistant construction of photovoltaic foundations and support components in extremely cold regions according to claim 1, characterized in that, In step two, the specific process flow is as follows: a hydraulic hammer is used to break the frozen soil, and a warming gun is used to heat the surface of the frozen soil layer to a softening depth of ≥100mm; a rotary drilling rig is used to drill a pilot hole, the pilot hole depth of which penetrates the thickness of the frozen soil layer; pile driving is carried out immediately after the pilot hole is completed; the injection height of the antifreeze thixotropic mud should be 200mm lower than the natural ground level, and graded sand and gravel should be backfilled on top to seal the opening and prevent the mud from overflowing and causing surface pollution.

4. The method for frost-resistant construction of photovoltaic foundations and support components in frigid regions according to claim 1, characterized in that, In step three, the specific parameters for the construction of the antifreeze cable trench are as follows: excavation depth ≥ 1.2m; a 100mm thick polyurethane foam insulation layer is laid at the bottom of the trench; a drainage slope of ≥ 3% is set at the bottom of the trench; a 1.5mm thick impermeable membrane is laid on both sides of the bottom of the trench; after the cable is laid, the trench is filled with graded sand and gravel, and the top is covered with 300mm thick plain soil and compacted in layers; in the backfill soil layer of the cable trench, a ventilated drainage valve is set every 10 meters to drain the condensate water generated in the trench due to the ground temperature difference, and to prevent it from accumulating, freezing and squeezing the cable.

5. The method for frost-resistant construction of photovoltaic foundations and support components in frigid regions according to claim 1, characterized in that, In step four: the bracket (2) is made of Q420-B steel, and low-temperature photovoltaic modules (21) and cold-resistant cables are selected; angle steel is added as a diagonal brace; the bracket (2) is bolted, and the "low-temperature torque compensation method" is used when installing the bolts. The metal shrinkage coefficient table is consulted according to the ambient temperature on the day of construction to correct the tightening torque, and low-temperature anti-loosening conductive paste is applied to the bolt threads; the clamp device (1) is designed to be adjustable, and is used to adjust the installation elevation of the components when there is a deviation in the foundation position or elevation; the clamp device (1) is lined with a low-temperature rubber damping pad, which is used to absorb the small displacement generated by the pipe pile and the bracket under different thermal expansion coefficients, and prevent stress concentration and breakage at the hard connection.

6. The method for frost-resistant construction of photovoltaic foundations and support components in extremely cold regions according to claim 1, characterized in that, In step five: ACR alloy connectors (7) are used to connect the component supports and the grounding grid, and cold pressing is used to connect them; ACR alloy connectors (7) grounding rings are laid 2m around the transformer box, and vertical grounding electrodes are set up to penetrate 2m below the depth of the frozen soil.

7. The method for frost-resistant construction of photovoltaic foundations and support components in extremely cold regions according to claim 1, characterized in that, It also includes full-cycle monitoring and dynamic adjustment steps: pre-embed temperature sensors and displacement sensors in the support foundation and the bottom of the transformer; build a dynamic operation and maintenance model based on frost heave data, and when the displacement sensor data indicates that the foundation has uneven settlement or rise of more than 3mm, the angle of the photovoltaic module is reversely compensated and adjusted by the adjustable clamp device on the support to ensure the overall flatness of the photovoltaic module array.

8. The method for frost-resistant construction of photovoltaic foundations and support components in extremely cold regions according to claim 5, characterized in that, The clamping device (1) includes: an arc plate (11), a reinforcing rib (12), a fixing bolt (13), and a pad (14). There are two arc plates (11), one of which is provided with the reinforcing rib (12) on its upper part, and the other arc plate (11) is connected to the arc plate (11) with the reinforcing rib (12) through the pad (14) and the fixing bolt (13). The two arc plates (11) are clamped on the concrete pipe pile (3).

9. The method for frost-resistant construction of photovoltaic foundations and support components in extremely cold regions according to claim 7, characterized in that, In the full-cycle monitoring process, the transmission and processing of sensor detection data are as follows: The temperature sensor and displacement sensor are connected to a wireless data acquisition terminal set up on site via signal lines. The wireless data acquisition terminal establishes a communication connection with a remote monitoring server through a mobile communication network and uploads the collected data packets in encryption. In addition to the base temperature and displacement, the detection data also includes water and heat migration parameters within the frozen soil layer. To this end, soil moisture sensors and pore water pressure gauges are added to soil layers at different depths around the base. The remote monitoring server calculates the unfrozen water content of the frozen soil layer based on the uploaded soil moisture content change gradient and pore water pressure dissipation data to determine the incubation period of frost heave.

10. The method for frost-resistant construction of photovoltaic foundations and support components in frigid regions according to claim 7, characterized in that, The full-cycle monitoring process also includes stress and attitude monitoring of the foundation and support structure: fiber optic strain sensors are pre-installed on the main reinforcement bars of the prestressed high-strength concrete pipe pile's steel cage. These fiber optic strain sensors are used to detect the axial tensile stress and bending stress data of the pile body under the action of frost heave force in frozen soil. MEMS dual-axis tilt sensors are installed on the top of the photovoltaic support column to detect the tilt angle data of the photovoltaic support relative to the horizontal plane along the X and Y axes. After receiving the above data, the remote monitoring server compares the real-time tensile stress data with a preset concrete crack resistance threshold and compares the tilt angle data with a preset angle deviation threshold. When any data exceeds the threshold, the server automatically generates an alarm command containing the fault pile number location information and sends it to the mobile terminal of the maintenance personnel.

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