This article mainly introduces the characteristics and application scope of ground-based photovoltaic power station independent foundation, strip foundation, precast pile foundation, bored pile foundation, steel spiral pile foundation.
I. Essentials of photovoltaic power station foundation and support design
Basic design
The loads acting on the basis of the photovoltaic module support mainly include the self-weight of the bracket and the photovoltaic module, wind load, snow load, temperature load, and seismic load. Among them, the wind load is mainly used for control. Therefore, the foundation should be designed to ensure the stability of the foundation under the wind load. Under the wind load, the foundation may have damage such as uplift and fracture. The foundation design should be able to ensure this effect. No damage occurs under force.
Connection design
The connections between the supports can be welded or bolted.
Bolted connections have a strong adaptability to structural deformation, small amount of steel and convenient production, fast and convenient construction and installation; welding and construction are slower, and steel plates need to be embedded in the foundation, and the amount of steel is large; Welders need a long-distance construction power supply to enter the site, and on-site welding is greatly affected by weather.
Independent foundation
Features of the independent foundation:
The form is simple, and the amount of excavation and backfill is large.
It requires less geological conditions and simple construction methods.
After excavation, there is no collapse of the foundation groove wall, and the formation rate of the foundation groove is high.
During the construction, the formwork is processed and formed at one time, which can be reused multiple times. The method of use is simple and can effectively increase the amount of pouring on a daily basis. During the construction process, the amount of earth excavation, the amount of concrete poured, the amount of reinforcing steel and the mechanical labor costs are small, and the economic benefits are obvious.
Scope of application:
It is suitable for photovoltaic power station projects with poor geological conditions that cannot meet the construction of cast-in-situ piles.
The construction soil layer generally contains blocks with a particle size greater than 10 mm, and the block content is high.
Second, the strip foundation
Features of the strip foundation:
The buried depth of the foundation can be relatively shallow, but the amount of excavation and backfill is large, and the amount of concrete is relatively large.
Scope of application:
This type of foundation is mostly used in flat uniaxial photovoltaic supports with poor foundation bearing capacity and high requirements for uneven settlement.
By setting up foundation beams between the front and rear pillars of the photovoltaic support, the center of gravity of the foundation is transferred between the front and rear pillars, and the foundation anti-overturning arm is added, which can resist the overturning moment of the photovoltaic support caused by wind load only by its own weight; The soil has a large contact area and is suitable for areas where the site is flat and the groundwater level is low. Because the base surface area is relatively large, it is generally buried between 200-300mm.
3. Precast pile foundation
Prefabricated piles are various materials and various forms of piles (such as wooden piles, concrete square piles, prestressed concrete pipe piles, steel piles, etc.) made at the factory or construction site. The piles are driven into and pressed by sinking equipment. Into or vibrate into the soil. The prefabricated piles used in China's construction industry are mainly two types: concrete prefabricated piles and steel piles.
Precast pile features:
It can be produced in batches, and the construction speed is fast. There is no filling and digging in the construction, and only simple field leveling is needed. However, when static pressure or hammering equipment is used to squeeze the pile into the soil, the pile is prone to fracture, and the top of the pile needs to be reinforced with reinforced mesh to increase the cost, and the verticality is not easy to guarantee.
Advantages: the production cost of precast piles is low, the reinforcement ratio is small, steel is saved, the hollow piles are environmentally friendly, the diameter is large, the specific surface area is large, the unilateral concrete has a large bearing capacity, the construction is simple, and the technical difficulty is low.
Disadvantages: The squeezing effect of precast piles is negative in a saturated cohesive soil, which can cause quality accidents such as broken piles and the necking of cast-in-situ piles. For squeezed soil precast concrete piles and steel piles, it will cause the pile body to float, reduce the bearing capacity, and increase Settlement; it is positive in loose soil and unsaturated fill, and it will play the role of densification and increase bearing capacity.
Application scope of the precast pile:
Mostly used for silty soil, cohesive soil, filling soil, collapsible loess, etc.
4. Bored pile foundation
Features of Bored Pile Foundation:
The whole formation is more convenient, the elevation of the top surface of the foundation can be adjusted according to the terrain, and the elevation of the top surface is easy to control. The amount of concrete reinforcement is small, the excavation is small, the construction is fast, and the original vegetation is destroyed at a low cost. However, there are holes and pouring on-site for concrete, which has higher requirements on the soil layer.
Application scope of the bored pile:
Applicable to silt with certain compactness or plastic and hard plastic silty clay. Suitable for general filling, cohesive soil, silt, sand, etc. It is not suitable for loose sandy soil layers, and the cobblestones or crushed stones with hard soil may not be easy to form holes.
Five, steel spiral pile foundation
After the 1880s, as an alternative pile-type spiral pile with unique advantages, it was widely used in the United States, Australia, and Europe and other countries, which can meet various engineering requirements such as compression resistance, resistance to pullout and resistance to horizontal forces.
Construction characteristics of spiral pile
A metal or non-metallic pipe pile or column pile with spiral blades is screwed into the ground with special equipment, and the top of the pile is connected to the load. Its advantages are fast and convenient construction, greatly shortening the construction period, environmentally friendly, environmentally friendly, and the destruction of vegetation can be implemented under various climatic conditions including northern winter, which can facilitate migration and recycling.
Anti-corrosion (durability) measures for spiral piles
1. The surface is coated with the anticorrosive layer. At present, the most widely used anti-corrosion measures for spiral piles used in photovoltaic power stations in China are to apply high-standard hot-dip zinc alloy coatings to the inside and outside of steel piles. After testing its adhesion using cutting hammer method, it has been proven reliable and effective. The on-site practice also proves that the alloy coating can be kept basically intact after being subjected to friction between construction screwing and soil.
2. Increase the corrosion allowance, that is, increase the wall thickness of the steel. The specifications of the spiral pile shaft steel pipe widely used in photovoltaic projects are outer diameter 76mm and wall thickness 4mm, even if it is buried in soil according to JG J94. The maximum corrosion amount of the steel pile on one side in the design life of 25 years is 1.25mm. After considering the corrosion amount, the tensile and compressive load that the pile body can still bear is about 130kN, which is much larger than the tensile or Compressive load (about 20kN)
Send feedback
History