Construction method of steep slope mountain photovoltaic micro pile foundation under complex geological conditions

Abstract

The invention discloses an abrupt slope mountain photovoltaic micro pile foundation construction method under complex geological conditions, and relates to the technical field of photovoltaic foundation construction. According to the method, in order to solve the problems that the slope of the abrupt-slope mountain land is large, the terrain is complex, large machines are difficult to operate, and the ecological environment is sensitive, the structural form of small-diameter pile groups and chamfered triangular bearing platforms is adopted, the heavy-load unmanned aerial vehicle hoisting technology is combined, and minimally invasive, efficient and green construction is achieved. The core of the method comprises the steps of construction preparation, measurement positioning, hole forming, reinforcement cage and bearing platform reinforcement installation, material transportation based on the heavy-load unmanned aerial vehicle, concrete pouring, maintenance and the like. The method is high in environmental adaptability, capable of overcoming 15-45-degree abrupt slopes and complex geological conditions and greatly reducing earth excavation and vegetation damage, high in structural bearing capacity and low in manufacturing cost, solves the problems that a traditional construction method is low in efficiency, serious in ecological damage and the like, and is suitable for mountain photovoltaic power station projects, particularly suitable for photovoltaic foundation construction of ecological sensitive areas.

Description

Technical Field

[0001] This invention relates to the field of photovoltaic foundation construction technology, specifically to a method for constructing photovoltaic micropile foundations on steep slopes under complex geological conditions. Background Technology

[0002] The demand for land for photovoltaic power generation projects is becoming increasingly scarce, and the construction of photovoltaic power stations is gradually extending to complex terrain areas such as mountains and hills. These areas are typically characterized by steep slopes, dramatic topographic relief, and complex geological conditions (such as abundant interbedded rocks and shallow rock strata), which bring many challenges to the construction of photovoltaic foundations.

[0003] Traditional photovoltaic (PV) support foundations mainly include independent extended foundations and long spiral cast-in-place piles, but they have significant drawbacks in steep mountainous terrain: First, large machinery cannot operate uphill, resulting in poor construction flexibility; second, the large volume of earthwork excavation not only leads to low construction efficiency but also severely damages surface vegetation and the original landform, causing soil erosion and failing to meet green construction requirements; third, the structural stress system is not reasonable enough, and the tensile, compressive, and overturning resistance needs to be improved to address the large wind loads that PV supports bear; fourth, material transportation is difficult, with traditional manual carrying being inefficient, and cableway construction damaging vegetation and being costly. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the existing technology and provide a construction method for photovoltaic micropile foundations on steep slopes under complex geological conditions. This method adopts a structural form of "small-diameter pile group + chamfered triangular pile cap" and combines heavy-duty UAV hoisting technology to effectively solve many problems faced in the construction of photovoltaic foundations on steep slopes.

[0005] The present invention relates to a construction method for photovoltaic micropile foundations on steep slopes under complex geological conditions, characterized in that the construction method includes the following steps: (1) Construction preparation: Clear the construction access road and set up safety ropes and anti-slip measures on steep slopes to ensure the safety of construction workers; based on the geological survey report, select small drilling equipment such as small pneumatic hand-held impact drills or QZ-150 lightweight down-the-hole drills to adapt to the mountainous working environment. (2) Measurement and positioning: Using RTK or total station for precise positioning, determine the center point of the chamfered triangular foundation and the specific hole positions of the three piles, and mark them with lime or wooden stakes to ensure the accuracy of the relative positions of the three piles, providing accuracy assurance for the subsequent installation of foundation reinforcement and formwork; (3) Hole forming construction: After the drilling rig is in place, a temporary working platform needs to be erected for steep slope sections to ensure the verticality of the drill rod. Drilling should be carried out using a 150mm diameter drill bit, with a drilling depth controlled at 1400mm. Impact drilling should be used when encountering hard rock, and rotary drilling should be used when encountering soil layers. After the borehole reaches the designed depth, high-pressure air or clean water should be used to remove any sediment from the borehole. During the drilling process, the pile diameter should be controlled to be ≥150mm, the pile length ≥1400mm, and the verticality deviation <1%. (4) Installation of reinforcing cage and foundation reinforcement: The prefabricated pile reinforcement cage is placed into the hole and kept centered. The pile reinforcement needs to extend into the pile cap and reliably connect with the pile cap reinforcement to form a whole. The pile cap reinforcement cage adopts a chamfered triangular shape, with two rows of longitudinal reinforcing bars at the top and bottom, and three structural longitudinal bars on each side. The stirrups are optimized into triangular stirrups to adapt to the layout of micro three-pile piles and reduce steel waste. The height of the chamfered triangular pile cap is 500mm, and the depth of the pile cap embedded in the soil is set according to the design requirements. (5) Material transport based on heavy-duty UAVs: Establish an "aerial supply chain": Set up drone logistics distribution centers at the foot of mountains or along gentle slopes, dividing them into "battery charging areas," "material loading areas," and "takeoff buffer zones." The ground at these distribution centers should be hardened or paved with wooden planks to ensure a level deviation of <5°. Set up no-fly zones with electronic fences around substations, high-voltage towers, and residential areas to prevent drones from entering. Use quadcopter, eight-propeller heavy-duty industrial drones with a lifting capacity of 70KG as transport vehicles, implementing "redundant loading" based on the drone's maximum effective payload, setting the single-lift weight to 80%-90% of the rated load, i.e., 25kg-40kg, to cope with the decrease in lift caused by canyon gusts and high altitude. Use high-strength plastic or aluminum alloy hoppers with a self-weight of <3kg for concrete / gravel transportation, equipped with bottom inserts. Pin-type or remote-controlled unloading ports prevent leakage during transportation; long components are hoisted using double-point binding to maintain a horizontal flight attitude; short components are loaded into special high-strength nylon lifting bags; adopting an "AB-point fully autonomous operation mode," the drone is started with one button at the distribution point, automatically flying to above the pile position, hovering at point B, and using a visual positioning system to hover at a height of 5-10 meters above the pile position. Ground receiving personnel, wearing safety helmets, confirm safety via walkie-talkie and then direct the drone to descend to 1-2 meters above the ground; ordinary materials are manually unhooked, while concrete hoppers are directly poured into the formwork by ground personnel opening the bottom valve, achieving "aerial material placement"; each drone is equipped with 4-6 sets of intelligent batteries and 2 high-power supercharged generators to ensure "one flight, two charges," achieving uninterrupted cyclical transportation; (6) Concrete pouring: C25 or C30 fine aggregate concrete is used for pile body grouting. During the pouring process, it should be vibrated to ensure compaction and prevent pile breakage or necking. Remove the laitance and a small amount of soil from the pile top, install the chamfered triangular formwork, and reinforce it firmly. Install the photovoltaic bracket pre-embedded bolts, strictly control the center deviation of the pre-embedded bolts to within ±2mm, and the elevation deviation to within ±5mm. Assign a special person to supervise and prevent displacement during concrete pouring. Pour the foundation concrete and finish the surface. (7) Curing: Curing shall begin within 12 hours after the concrete is poured. Cover with a film and sprinkle with water. The curing time shall be no less than 7 days to ensure that the concrete strength meets the standard. The construction of photovoltaic micropiles can then be completed.

[0006] The method for constructing photovoltaic micropile foundations on steep slopes under complex geological conditions, as described in this invention, has the following advantages: Strong environmental adaptability: This invention uses miniaturized equipment for construction, which can overcome unfavorable conditions such as steep slopes of 15°~45°, soil layers with stones, exposed bedrock and large terrain undulations. It does not require large-scale site leveling, has extremely high construction flexibility, and is suitable for steep mountain slopes under complex geological conditions. Good ecological protection effect: The foundation is small and the amount of earthwork excavation is minimal. Only the topsoil within a 30cm diameter of the pile position is removed, avoiding large-scale damage to surface vegetation and original landforms, and the water and soil conservation effect is good. The rock powder and a small amount of mud produced by drilling are discharged into a special mobile sedimentation tank. Construction waste is centrally treated with "carry-in and carry-out" measures. Dust and noise reduction measures are in place, which meets the requirements of green construction and ecological protection. The structure is rationally stressed and has a high bearing capacity: It utilizes a "tripod" stabilization system formed by three micropiles, combined with a chamfered triangular reinforced concrete pile cap, to connect the three independent piles into a whole. The tensile, compressive, and overturning resistance is significantly enhanced compared to single pile foundations. It is especially suitable for photovoltaic supports that bear large wind loads. Through load transfer, the upper load is evenly transferred to the three micropiles, effectively solving the problems of anti-slippage and anti-overturning on steep slopes. High construction efficiency: Heavy-duty drones are used for material hoisting, establishing an "aerial supply chain" to replace traditional manual carrying or cableway transportation. In conditions with steep slopes and large elevation differences, the material transfer efficiency is increased by 3-5 times, greatly improving construction efficiency. Low cost: Through structural optimization, the foundation is designed as a chamfered triangle and the stirrups are optimized to triangular stirrups. Under the premise of ensuring structural safety, the amount of concrete used is reduced by about 15% and the amount of steel bars is reduced by about 10%. Moreover, the micropile is only 1400mm long, which saves a lot of earthwork excavation, transportation and slope protection costs. The overall labor and machinery costs are reduced by about 20%, resulting in significant economic benefits. Attached Figure Description

[0007] Figure 1 This is a process flow diagram of the present invention. Detailed Implementation

[0008] Example 1: A construction method for photovoltaic micropile foundations on steep slopes under complex geological conditions, comprising the following steps: I. Pre-construction preparation stage (I) Site survey and plan refinement Before construction, a comprehensive and detailed on-site survey was conducted, focusing on key information such as topographic slope, geological stratification, soil and rock properties, distribution of underground obstacles, and sensitive points in the surrounding ecological environment. Taking the Damikou photovoltaic power generation project in Nujiang Prefecture as an example, the project site has an elevation between 1710 and 3250 meters, with significant topographic relief and slopes ranging from 15 to 45 degrees, with some areas exceeding 45 degrees. The area has a complex geological structure, with well-developed faults and strong neotectonic activity. The exposed strata are mainly loose soil and relatively hard to hard rock formations, and there are also adverse geological phenomena such as gullies, rock weathering, and karstification. Based on these survey results, the construction plan was refined, specifying key parameters such as the arrangement density, pile length, and pile diameter of micropiles. For areas with slopes exceeding 35 degrees, an additional plan for the construction of specialized work platforms was developed. Simultaneously, an ecological environment status survey of the construction area was completed, marking the distribution areas of native vegetation and soil and water conservation sensitive zones, providing accurate data for the implementation of subsequent minimally invasive construction and ecological protection measures. (II) Equipment and Material Preparation Equipment Selection and Commissioning: Based on the geological survey report, select suitable miniaturized construction equipment. For drilling equipment, prioritize the QZ-150 lightweight down-the-hole drill or a small pneumatic handheld impact drill; equip with an air compressor with a capacity of 10-20 m³ / min to provide sufficient power for drilling and hole cleaning operations; prepare a 30kW portable generator to ensure stable power supply on site; use a JZC350 concrete mixer for concrete mixing; select a TS06 / V90 total station or RTK for surveying and positioning to ensure positioning accuracy; and use a ZX-50 handheld vibrator for concrete compaction. Material Procurement and Inspection: HPB300 and HRB400 steel bars are selected for the fabrication of pile reinforcement cages and pile cap reinforcement. The pile cap reinforcement needs to be custom-made according to the chamfered triangle structure. C25 or C30 fine aggregate concrete is used, and its aggregate gradation needs to be adapted to the micropile hole size and drone lifting requirements to avoid segregation. Composite wood formwork or standardized steel molds are selected for the formwork, and they need to be customized according to the chamfered triangle size to ensure the strength and sealing of the formwork. For areas with weak soil layers, Φ160mm PVC sleeves can be used for wall protection. (III) Site Arrangement and Safety Protection Construction access roads and work platforms: Clear construction access roads to ensure that small equipment and materials can be transported to the edge of the work area; for work areas with a slope greater than 25°, use steel pipes to build simple horizontal working platforms, drive ground anchors into the bottom of the platforms for fixation, and conduct anti-overturning calculations to ensure that the platform's load-bearing capacity meets the construction requirements. Safety protection facilities: Safety ropes are installed at the edge of the steep slope working area. The safety ropes are made of high-strength steel wire ropes. Construction of a drone logistics distribution center: The center will be set up at the foot of a mountain or along a gentle slope, clearly defining a "battery charging area," a "material loading area," and a "takeoff buffer zone." The ground at the distribution point will be hardened with concrete or paved with wooden planks to ensure a level deviation of less than 5°, providing a stable site for drone takeoff and landing. Electronic fences will be erected around substations, high-voltage towers, and living areas to define no-fly zones. Flight boundaries will be demarcated using a GPS positioning system to prevent drones from accidentally entering dangerous areas when their signals are lost. II. Core Construction Phase (a) Measurement and positioning Precise positioning was achieved using a TS06 / V90 total station or RTK. First, the coordinates of the center point of the chamfered triangular foundation were determined according to the construction drawings. Then, using the center point as a reference, the specific locations of the three micropiles were determined according to the design spacing, with the hole position deviation controlled within ±50mm. After positioning, clear markings were made with lime or wooden stakes, and protective markers were placed around the hole positions to prevent disturbance during construction. Multiple checks were required during the measurement process to ensure the accuracy of the relative positions of the three piles, laying the foundation for the subsequent installation accuracy of the foundation reinforcement and formwork. (2) Hole forming construction Drilling rig positioning: Move the successfully tested drilling rig to the work platform, adjust its position to ensure the drill rod centerline coincides with the hole centerline, and ensure the drill rod verticality deviation is less than 1%. The drilling rig is secured using ground anchors or counterweights to prevent displacement or tilting during drilling. Drilling operation: A 150mm diameter drill bit is used for drilling. The drilling depth is controlled at 1400mm according to the design requirements. If the bedrock is shallow, the drilling depth can be adjusted appropriately according to the rock penetration depth requirements. During the drilling process, the drilling method is selected according to the properties of the rock and soil. When encountering hard rock, percussion drilling is used, and the percussion frequency is controlled at 30-50 times / min. When encountering soil or loose gravel layers, rotary drilling is used, and the rotation speed is controlled at 50-80 r / min. During the drilling process, the rock and soil layering, drilling speed, and obstacles encountered are recorded in real time. If underground obstacles cannot be avoided and the hole position needs to be shifted, the design unit's consent must be obtained, and the measurement and positioning must be re-performed. Hole cleaning: After the hole reaches the designed depth, high-pressure air or clean water is used for hole cleaning. When using an air compressor, the air duct is inserted into the bottom of the hole, and the high-pressure airflow blows upwards from the bottom of the hole, carrying away the sediment and rock powder inside the hole. If clean water is used, clean water needs to be injected and discharged multiple times until the thickness of the sediment at the bottom of the hole meets the specifications, generally controlled within 50mm. After the hole cleaning is completed, the hole position, hole depth, hole diameter, and verticality are inspected. Only after the inspection is passed can the next process be carried out. (III) Fabrication and Installation of Reinforcing Cage Reinforcing cage fabrication: The pile body reinforcing cage is fabricated according to the design dimensions. The main reinforcement uses HRB400 steel bars with a diameter determined according to design requirements, generally 12-16mm. The stirrups use HPB300 steel bars with a diameter of 6-8mm and a spacing of 100-200mm. The length of the reinforcing cage is slightly longer than the pile length, with a reserved anchorage length for extending into the pile cap, generally not less than 30d (d is the diameter of the main reinforcement). The pile cap reinforcing cage adopts a chamfered triangular shape, with two rows of longitudinal reinforcing bars at the top and bottom, and three structural longitudinal bars on each side. The stirrups are optimized to triangular stirrups with a spacing of 75mm to adapt to the layout of micro-pile three-pile structures and reduce steel waste. During the fabrication of the reinforcing cage, the cutting length, bending angle, and binding quality of the reinforcing bars are strictly controlled to ensure that the dimensional deviations of the reinforcing cage meet the specifications, and the thickness of the protective layer of the main reinforcement is controlled at 50mm. Reinforcing cage installation: The pile reinforcing cage is placed into the hole using a combination of manual labor and drone hoisting. During hoisting, the reinforcing cage is kept vertical to avoid collision with the hole wall and causing collapse. After the reinforcing cage is placed in the hole, its position is adjusted to ensure it is centered. The top of the reinforcing cage is fixed to a temporary support at the hole opening with lifting rods to prevent the reinforcing cage from floating or shifting during concrete pouring. The pile reinforcing bars must extend into the pile cap and be reliably connected to the pile cap reinforcing bars by binding or welding to form an integral load-bearing system. (iv) Material transport based on heavy-duty UAVs Unitized packaging of materials: Concrete / aggregate is loaded into hoppers made of high-strength plastic or aluminum alloy. The hoppers weigh less than 3kg and their capacity is determined based on the weight of a single drone lift, generally 25-40kg. The bottom of the hopper is equipped with a pin-type or remote-controlled unloading port to ensure no leakage during transportation. Long rods, such as bracket purlins, are lifted using double-point binding. The spacing between binding points is determined based on the length of the rod, generally 1.5-2m, to maintain a horizontal flight attitude. Short components, such as embedded parts and cement bags, are packed into special high-strength nylon lifting bags. The bags are securely sealed to prevent scattering during transportation. Drone flight operations: A quadcopter, eight-propeller heavy-duty industrial drone with a lifting capacity of 70KG, such as the T70, is used to implement a "fully autonomous operation mode at point A and B". After the pilot loads the materials at the distribution point (point A), the drone is started with one button. The drone automatically flies to the pile position (point B) according to the preset route. During the flight, the drone uses a visual positioning system to adjust its attitude in real time to avoid obstacles such as high-voltage lines and communication base stations. The drone hovers 5-10 meters above the pile position. Ground personnel wearing safety helmets confirm safety with the pilot via walkie-talkie and then direct the drone to descend to 1-2 meters above the ground. For ordinary materials, manual assistance is used for unloading. For concrete hoppers, ground personnel open the bottom valve to directly inject concrete into the hole or formwork, achieving "aerial material placement". Circular transport support: Each drone is equipped with 4-6 sets of smart batteries and 2 high-power supercharged generators to achieve a "fly once, charge twice" cycle mode; the battery charging area is equipped with dedicated personnel to be responsible for battery replacement and charging to ensure uninterrupted drone operation; at the same time, a dedicated meteorological observer is set up on site to monitor wind speed and weather changes in real time. When the wind speed exceeds level 5 or encounters severe weather such as heavy rain or dense fog, the drone hoisting operation will be stopped immediately to ensure flight safety. (v) Concrete pouring Pile body concrete pouring: C25 or C30 fine aggregate concrete is transported by drone for pile body pouring. A layered pouring method is adopted, with each layer's height controlled within 500mm. A ZX-50 handheld vibrator is used for compaction, with vibration points spaced no more than 300mm apart, and a vibration time of 20-30 seconds, until the concrete surface shows a layer of slurry and no air bubbles emerge, ensuring the concrete is compacted and free from pile breakage or necking. During the pouring process, the concrete pouring height is measured in real time to ensure the pile body concrete is poured to the design elevation. Foundation concrete pouring: After the pile body concrete is poured, before it initially sets, remove the laitance and a small amount of soil from the pile top. The foundation embedment depth should be in accordance with the design requirements, generally 100-200mm. Install chamfered triangular formwork, and seal the formwork joints with sealant to prevent grout leakage. The formwork is reinforced with steel pipe supports and tie bolts to ensure its stability. Install the photovoltaic bracket embedded bolts, strictly controlling the center deviation of the embedded bolts to within ±2mm and the elevation deviation to within ±5mm. During concrete pouring, assign a dedicated person to monitor the process to prevent the embedded bolts from shifting. Use drones to hoist and pour concrete for the foundation. During the pouring process, pour continuously from one side of the foundation to the other, vibrate to compact, and finish and smooth the surface promptly after pouring. (vi) Curing and demolding Curing should begin within 12 hours of concrete pouring, using a method of covering with plastic film and sprinkling water to keep the concrete surface moist, with a curing time of no less than 7 days. During the curing period, avoid collisions between construction machinery and the foundation, and do not pile heavy objects on the foundation platform. The formwork can only be removed when the concrete strength reaches more than 75% of the design strength. During the formwork removal process, avoid violent dismantling to prevent damage to the edges and corners of the foundation platform and the embedded bolts. After the formwork is removed, the foundation surface should be cleaned and the appearance quality of the foundation should be inspected. If defects such as honeycomb or pitting are found, they should be repaired in a timely manner. III. Construction and Acceptance Stage (a) Quality Inspection Appearance quality inspection: Inspect the pile position deviation, pile verticality, pile cap size and appearance quality of the micropile foundation. The pile position deviation shall not exceed 100mm, the pile verticality deviation shall be less than 1%, the pile cap size deviation shall be controlled within ±10mm, and the foundation surface shall be free of obvious cracks, honeycomb, holes and other defects. Strength and density testing: Concrete test blocks are retained as required. Each group of test blocks is cured for 28 days according to standard and then subjected to compressive strength test. The test results must meet the design strength grade requirements. The density of the pile concrete is tested. If necessary, low strain testing method is used to test the integrity of the pile body to ensure that there are no quality problems such as broken piles or necking. Pull-out bearing capacity test: After the project is completed, the foundations shall be randomly selected according to the proportion for pull-out bearing capacity test. The number of selected foundations shall not be less than 1% of the total number of foundations and not less than 3 groups. The test shall adopt the slow sustained load method, and the load shall be applied to 1.5 times the design pull-out load or until the foundation fails. The test results shall meet the design wind pull-out resistance requirements. (II) Safety and Environmental Protection Acceptance Safety facility acceptance: Check whether the safety protection facilities at the construction site are intact, whether safety ropes, work platforms, warning signs, etc. meet the specifications, whether the safety management measures for drone hoisting are implemented in place, and whether the emergency plan is operable; Environmental protection measures acceptance: Verify the soil and water conservation situation, check whether the rock powder and mud generated from drilling are discharged into a dedicated mobile sedimentation tank, and whether there is any turbid water flowing into rivers; check the backfilling and revegetation of the construction disturbance area, and whether grass seeds such as tall fescue and ryegrass adapted to the local climate are sown on the exposed surface; check whether the construction waste is centrally disposed of according to the "bring in and take out" principle, and whether it is buried in the mountain; test whether the dust and noise at the construction site meet the environmental protection standards; (III) Completion Acceptance Collect and organize all technical data from the entire construction process, including construction drawings, survey reports, equipment commissioning records, material inspection reports, construction logs, quality inspection reports, and safety and environmental protection acceptance records, to form complete as-built documentation. Organize a final acceptance inspection involving the construction unit, contractor, supervision unit, and other relevant parties, conducting a comprehensive assessment of the project's quality, safety, and environmental protection aspects. Upon successful inspection, sign the final acceptance report, and the project is officially handed over for use.

Claims

1. A construction method for photovoltaic micropile foundations on steep slopes under complex geological conditions, characterized in that, Includes the following steps: (1) Construction preparation: Clear the construction access road, set up safety ropes and anti-slip measures in steep slope sections, and select small drilling equipment according to the geological survey report; (2) Measurement and positioning: Use RTK or total station to accurately locate the center point of the chamfered triangular foundation and the specific hole positions of the three piles, and mark them with lime or wooden stakes; (3) Hole construction: The drilling rig is positioned and a temporary working platform is set up. Drilling is carried out using a 150mm diameter drill bit. The drilling depth is controlled at 1400mm. When encountering hard rock, impact drilling is used, and when encountering soil, rotary drilling is used. After the hole is formed, high-pressure air or clean water is used to clean the hole. (4) Installation of reinforcement cage and pile cap reinforcement: The pre-made pile reinforcement cage is placed into the hole and kept in the center. The pile reinforcement extends into the pile cap and is reliably connected to the pile cap reinforcement. The pile cap reinforcement cage adopts a truncated triangular shape. The longitudinal reinforcement is set in two rows at the top and bottom, and three structural longitudinal reinforcements are set on each side. The stirrups are triangular stirrups. (5) Material transportation based on heavy-duty UAVs: Set up UAV logistics distribution centers at the foot of mountains or along gentle slopes, divide functional areas and set up electronic fences, implement "redundant loading" according to the maximum effective payload of UAVs, and use AB point fully autonomous flight mode to hoist materials such as steel cages, concrete, and steel bars. Each UAV is equipped with 4-6 sets of smart batteries and 2 high-power supercharged generators to achieve uninterrupted cyclic transportation. (6) Concrete pouring: C25 or C30 fine stone concrete is used to pour the pile body and vibrate it to make it dense. The corner-cut triangular template and photovoltaic bracket pre-embedded bolts are installed. The foundation concrete is poured and the surface is finished and smoothed. (7) Curing: Cover the concrete with a film and sprinkle water for curing within 12 hours after the concrete is poured. The curing time shall not be less than 7 days.

2. The construction method for photovoltaic micropile foundations on steep slopes under complex geological conditions as described in claim 1, characterized in that, The small drilling equipment mentioned in step (1) is a small pneumatic hand-held impact drill or a QZ-150 lightweight down-the-hole drill.

3. The construction method for photovoltaic micropile foundations on steep slopes under complex geological conditions as described in claim 1, characterized in that, In step (3), the pile diameter deviation shall not be less than 150 mm, the pile length deviation shall not be less than 1400 mm, and the verticality deviation shall not be less than 1%.

4. The construction method for photovoltaic micropile foundations on steep slopes under complex geological conditions as described in claim 1, characterized in that, In step (4), the height of the chamfered triangular foundation is 500mm, and the depth of the foundation embedded in the soil is set according to the design requirements.

5. The construction method for photovoltaic micropile foundations on steep slopes under complex geological conditions as described in claim 1, characterized in that, The drone mentioned in step (5) is a quadcopter-eight-propeller heavy-duty industrial drone with a lifting weight of 70KG. The weight of a single lift is 80%-90% of the rated load, i.e., 25kg-40kg.

6. The construction method for photovoltaic micropile foundations on steep slopes under complex geological conditions as described in claim 1, characterized in that, In step (5), concrete / sand and gravel transportation uses high-strength plastic or aluminum alloy hoppers with a self-weight of <3kg, and the bottom is equipped with a pin-type or remote-controlled unloading port; long rods are hoisted by double-point binding, and short components are put into special high-strength nylon hanging bags.

7. The construction method for photovoltaic micropile foundations on steep slopes under complex geological conditions as described in claim 1, characterized in that, In step (5), the drone hovers 5-10 meters above the pile position. After the ground receiving personnel confirm that it is safe, it descends to 1-2 meters above the ground. Ordinary materials are manually unhooked, and concrete hoppers are directly poured into the formwork by the ground personnel opening the bottom valve.

8. The construction method for photovoltaic micropile foundations on steep slopes under complex geological conditions as described in claim 1, characterized in that, In step (6), the center deviation of the pre-embedded bolts is controlled within ±2mm, and the elevation deviation is controlled within ±5mm.

Images