Design method and structure of rock area photovoltaic support circular truncated cone foundation

Abstract

The application discloses a design method and structure of a round-truncated-cone-shaped foundation of a photovoltaic support in a rock area, and the method comprises the following steps: S1, determining an implementation area; S2, obtaining a standard value of a downward pressure P, a standard value of an uplift force T, a standard value of a horizontal force V and a bending moment M acting on the round-truncated-cone-shaped foundation; S3, determining initial parameters of the round-truncated-cone-shaped foundation according to the structure of the photovoltaic support and the load acting on the round-truncated-cone-shaped foundation, and combining the design specifications of the foundation slab and the anchor rod; S4, calculating the comprehensive bearing capacity of the round-truncated-cone-shaped foundation according to the initial parameters of the round-truncated-cone-shaped foundation; and S5, checking the parameters of the round-truncated-cone-shaped foundation. The application provides sufficient uplift resistance, horizontal resistance, compression resistance and shearing resistance bearing capacity for the support column of the photovoltaic support by utilizing the stress characteristics of the photovoltaic support structure, ensures the safety of the bearing capacity of the foundation, reduces the foundation engineering cost, and simultaneously shortens the construction period of the integrated construction of the photovoltaic support steel column and the foundation.

Description

Technical Field

[0001] This invention belongs to the field of geotechnical engineering and foundation technology, and particularly relates to a design method and structure for a frustum-shaped foundation for photovoltaic supports in rocky areas. Background Technology

[0002] With the continuous and in-depth implementation of the dual-carbon strategy, photovoltaic power generation projects in my country have become an important part of new energy power generation technology. They receive solar radiation through photovoltaic modules and then convert light energy into electrical energy. Photovoltaic support structures are the structural carriers that support photovoltaic modules. Their foundations are required to have good load-bearing capacity, be quick to construct, adapt to different geological conditions, and have good engineering economics.

[0003] For photovoltaic projects in rocky areas, due to the hardness of the rocks and the fact that most of the rocks are exposed on the surface, conventional engineering methods using bored piles would encounter problems such as drilling difficulties and difficulty in transporting construction machinery. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a design method and structure for a frustum-shaped foundation for photovoltaic (PV) systems in rocky areas. This method increases the foundation's pull-out bearing capacity through the anchoring force of rock anchors within the bedrock; increases the foundation's compressive bearing capacity through the self-weight of the foundation platform, the friction between the outer side of the platform and the soil, and the end resistance of the rock anchors; and increases the horizontal force resistance through the end resistance of the inclined rock anchors and the foundation platform's embedding in the rock. This ensures the frustum-shaped foundation has sufficient bearing capacity, reduces foundation engineering costs, facilitates construction, and shortens the construction period for integrated PV support steel columns and foundations. It is not only highly suitable for PV power station projects in mountainous areas with exposed bedrock but can also adapt to different geological conditions.

[0005] The objective of this invention is achieved through the following technical solution:

[0006] A design method for a frustum-shaped foundation for a photovoltaic support system in rocky areas includes the following steps:

[0007] Step S1: Determine the implementation area;

[0008] Step S2: Obtain the standard values ​​of the downward force P, upward force T, horizontal force V, and bending moment M acting on the frustum-shaped foundation;

[0009] Step S3: Based on the structure of the photovoltaic support and the magnitude of the load acting on the frustum-shaped foundation, and in conjunction with the design specifications of the foundation platform and anchor bolts, determine the initial parameters of the frustum-shaped foundation.

[0010] Step S4: Calculate the comprehensive bearing capacity of the frustum foundation based on the initial parameters of the frustum foundation;

[0011] Step S5: Verify the parameters of the frustum foundation based on its comprehensive bearing capacity;

[0012] If the verification fails, the design parameters of the frustum foundation shall be adjusted and the verification shall be performed again.

[0013] If the verification is successful, the design of the frustum-shaped foundation is complete.

[0014] In one embodiment, step S1 includes:

[0015] The area of ​​multiple intact bedrocks exposed on the surface of the project area is obtained and classified according to their area size. At the same time, the thickness of the shallow soil layer of each intact bedrock is obtained, and the area with a shallow soil layer thickness of less than 300mm and a large area of ​​intact bedrock is selected as the implementation area.

[0016] In one implementation, step S2 includes:

[0017] The structural form of the photovoltaic support is obtained, and its structure is calculated and analyzed according to multiple loads to obtain the standard values ​​of the downward force P, upward force T, horizontal force V, and bending moment M acting on the frustum-shaped foundation.

[0018] The multiple loads include engineering wind load, snow load, the self-weight load of the photovoltaic support, and seismic action.

[0019] In one implementation, step S3 includes:

[0020] The bending moment M is converted into the tensile or pull-out axial force borne by the anchor rod. The inclination angle, size, and anchorage depth of the anchor rod are determined according to the magnitude of the force. The size of the foundation cap is then determined according to the inclination angle of the anchor rod. The initial parameters of the frustum-shaped foundation are obtained by combining the minimum spacing requirements of the anchor rods and the minimum size requirements of the foundation cap.

[0021] In one implementation, step S4 includes:

[0022] Calculate the pull-out bearing capacity Ta of the foundation cap based on its self-weight and the pull-out force of the rock anchor; calculate the horizontal bearing capacity Va of the foundation cap based on the earth pressure in the active and passive zones of the foundation cap and the shear force of the anchor; calculate the compressive bearing capacity Pa of the foundation cap based on the external skin friction of the foundation cap and the end resistance of the anchor; calculate the flexural bearing capacity Ma of the foundation cap based on its bending force.

[0023] In one implementation, step S5 includes:

[0024] Compare the magnitudes of tensile bearing capacity Ta and the standard value of upward pull force T, horizontal bearing capacity Va and the standard value of horizontal force V, compressive bearing capacity Pa and the standard value of downward force P, and bending bearing capacity Ma and the standard value of bending moment M.

[0025] The design of the frustum-shaped anchor rod is completed only when T≤Ta, V≤Va, P≤Pa, and M≤Ma occur simultaneously.

[0026] The present invention also provides a structure for a frustum-shaped foundation for a photovoltaic support in rocky areas, comprising a frustum-shaped foundation platform and an anchor rod that is inclined and anchored into the foundation rock. The steel column of the photovoltaic support is inserted into the foundation platform, and the anchor rod is connected to the steel column. The anchor rod is set in the foundation platform and integrally cast with the foundation platform.

[0027] In one embodiment, a reinforcing frame is also provided within the foundation cap, the reinforcing frame including reinforcing steel bars extending in the vertical direction and in the horizontal direction respectively.

[0028] In one embodiment, the anchor bolts are evenly spaced along the circumference of the steel column.

[0029] In one embodiment, the bottom of the foundation cap is embedded in the foundation rock.

[0030] The beneficial effects of this invention are as follows:

[0031] The foundation cap adopts a frustum-shaped structure, and the anchor rods are in the form of oblique anchor rods. This ensures that the foundation shape conforms to the direction of the internal forces acting on the photovoltaic support steel column, solving the problem of the minimum punching shear protection safety distance for rock anchor rods within the foundation cap. This minimizes the amount of engineering materials used while ensuring the foundation's bearing capacity. This invention fully utilizes the inherent properties of bedrock. The anchoring force of the anchor rods within the bedrock increases the foundation's pull-out bearing capacity. The self-weight of the foundation cap, the friction between the outer side of the cap and the soil, and the end resistance of the rock anchor rods increase the foundation's compressive bearing capacity. The end resistance of the oblique rock anchor rods and the embedding of the foundation cap into the bedrock increase the horizontal force bearing capacity, ensuring that the foundation has sufficient bearing capacity. This reduces the cost of foundation engineering, facilitates construction, and shortens the construction period for the integrated construction of the photovoltaic support steel column and foundation. It is not only highly suitable for mountain photovoltaic power station projects with intact exposed bedrock but can also adapt to different geological conditions. Attached Figure Description

[0032] The invention will now be described in more detail with reference to embodiments and the accompanying drawings.

[0033] Figure 1 A flowchart illustrating the design method of the present invention is shown;

[0034] Figure 2 The diagram shows a frustum-shaped foundation and photovoltaic support of the present invention after installation.

[0035] Figure 3 A schematic diagram of the frustum-shaped base of the present invention is shown;

[0036] Figure 4 This shows a schematic diagram of the frustum-shaped foundation of the present invention in another direction;

[0037] In the accompanying drawings, the same parts use the same reference numerals. The drawings are not to scale.

[0038] Figure label:

[0039] 1-Foundation platform, 2-Photovoltaic support, 11-Anchor hole, 12-Anchor, 13-Reinforcing steel bar, 21-Steel column. Detailed Implementation

[0040] The invention will now be further described with reference to the accompanying drawings.

[0041] Example 1

[0042] This invention provides a design method for a frustum-shaped foundation for photovoltaic supports in rocky areas, such as... Figure 1 As shown, it includes the following steps;

[0043] Step S1: Determine the implementation area based on geological conditions and on-site construction conditions; obtain the area of ​​multiple intact bedrocks exposed on the surface of the project area and classify them according to their area size; at the same time, obtain the thickness of the shallow soil layer of each intact bedrock; and select the area with a shallow soil layer thickness of less than 300mm and a large area of ​​intact bedrock as the implementation area.

[0044] Step S2: Obtain the standard values ​​of the downward force P, upward force T, horizontal force V, and bending moment M acting on the frustum-shaped foundation;

[0045] Specifically, in step S2, the structural form of the photovoltaic support is first obtained, and its structure is calculated and analyzed according to multiple loads to obtain the standard value of the downward pressure P, the standard value of the upward force T, the standard value of the horizontal force V, and the bending moment M acting on the frustum-shaped foundation.

[0046] The multiple loads include engineering wind load, snow load, the self-weight load of the photovoltaic support and seismic action;

[0047] Step S3: Based on the structure of the photovoltaic support and the magnitude of the load acting on the frustum-shaped foundation, according to the principle of structural mechanics equilibrium, and in conjunction with the design specifications of the foundation platform and anchor rods, determine the initial parameters of the frustum-shaped foundation.

[0048] Specifically, the bending moment M is converted into the tensile or pull-out axial force borne by the anchor rod. The inclination angle, size, and anchorage depth of the anchor rod are determined according to the magnitude of the force. The size of the foundation cap is then determined according to the inclination angle of the anchor rod. The initial parameters of the frustum-shaped foundation are obtained by combining the minimum spacing requirements of the anchor rods and the minimum size requirements of the foundation cap.

[0049] Step S4: Calculate the overall bearing capacity of the frustum-shaped foundation;

[0050] Specifically, the tensile bearing capacity Ta of the foundation cap is calculated based on its self-weight and the pull-out force of the rock anchor; the horizontal bearing capacity Va of the foundation cap is calculated based on the earth pressure in the active and passive zones of the foundation cap and the shear force of the anchor; the compressive bearing capacity Pa of the foundation cap is calculated based on the external skin friction of the foundation cap and the end resistance of the anchor; and the bending bearing capacity Ma of the foundation cap is calculated based on its bending force.

[0051] Step S5: Verify the parameters of the frustum foundation based on its comprehensive bearing capacity;

[0052] Specifically, compare the magnitudes of the pull-out bearing capacity Ta and the standard value of the pull-out force T, the horizontal bearing capacity Va and the standard value of the horizontal force V, the compressive bearing capacity Pa and the standard value of the downward force P, and the flexural bearing capacity Ma and the standard value of the bending moment M.

[0053] When T≤Ta, V≤Va, P≤Pa and M≤Ma are simultaneously satisfied, the design of the frustum-shaped anchor rod is completed.

[0054] If any of the bearing capacities does not meet the requirements, the design parameters of the frustum-shaped foundation are adjusted according to the comparison results, and then recalculated and compared with the standard values ​​until T≤Ta, V≤Va, P≤Pa and M≤Ma are simultaneously satisfied, thus completing the design of the frustum-shaped anchor.

[0055] It should be noted that due to the specifications for pier foundations, such as the minimum spacing between anchor bolts and the minimum dimensions of the pier, there are corresponding regulations. This means that after initially calculating the parameters of the truncated cone foundation, such as the pier dimensions, anchor bolt inclination angle, anchorage depth, and anchor bolt dimensions based on the internal forces, the foundation requirements may not be met. In this case, the parameters need to be fine-tuned. Under the premise of meeting the specifications, the calculations should be checked. It is possible that the overall bearing capacity does not meet the standard requirements. In this case, further adjustments need to be made based on the actual results until the overall bearing capacity of the truncated cone foundation meets the standard requirements. Once the design of the truncated cone foundation is completed, the photovoltaic support can be fixed at the location of the determined construction area.

[0056] This embodiment provides a design method for a frustum-shaped foundation for photovoltaic (PV) systems in rocky areas. It fully utilizes the inherent properties of the bedrock, increasing the foundation's pull-out bearing capacity through the anchoring force of rock anchors within the bedrock; increasing the foundation's compressive bearing capacity through the self-weight of the foundation platform, the friction between the outer side of the platform and the soil, and the end resistance of the rock anchors; and increasing the horizontal force bearing capacity through the end resistance of the inclined rock anchors and the foundation platform's embedding in the rock. This ensures the foundation has sufficient bearing capacity, reduces foundation engineering costs, facilitates construction, and shortens the construction period for integrated PV support steel columns and foundations. It is not only highly suitable for PV power station projects in mountainous areas with exposed bedrock but can also adapt to various geological conditions.

[0057] Example 2

[0058] This embodiment provides a structure for a frustum-shaped foundation of a photovoltaic support 2 in a rocky area, including a frustum-shaped foundation platform 1 and an anchor rod 12 that is inclined and anchored into the foundation rock. The steel column 21 of the photovoltaic support 2 is inserted into the foundation platform 1, and the anchor rod 12 is connected to the steel column 21. The anchor rod 12 is set in the foundation platform 1 and is integrally cast with the foundation platform 1.

[0059] Furthermore, a reinforcing frame is also provided inside the foundation cap 1, which includes reinforcing steel bars 13 extending in the vertical direction and in the horizontal direction respectively.

[0060] Furthermore, the bottom of the foundation cap 1 is embedded in the foundation rock;

[0061] Specifically, the anchor bolts 12 are driven into the holes 11 at a certain angle, and the anchor bolts 12 are set inside the holes 11 and extend above the ground from the holes 11. In the reinforced frame, the dimensions of the reinforcing steel bars 13 extending vertically are... The dimensions of the horizontally extending reinforcing steel bar 13 are as follows: Depending on the magnitude of the force, the number of anchor bolts 12 can be set to 3 or 4, with multiple anchor bolts 12 evenly spaced along the circumference of the steel column 21;

[0062] The top outer diameter of the foundation cap 1 is set between 400-600mm, and the bottom outer diameter is set between 700-800mm. The concrete grade is not lower than C30. When the wind load of the project is large, a larger thickness should be set to increase the self-weight to resist the upward force. The grade of the reinforcing steel is not lower than HRB300, the grade of the anchor rod 12 steel is not lower than HRB400, and the height of the truncated cone-shaped foundation cap is between 500-600mm.

[0063] It should be noted that the foundation cap 1 is a solid reinforced concrete frustum structure. This structural form allows for a larger contact area between the foundation and the soil with less concrete, ensuring sufficient bearing capacity. At the same time, it fully utilizes the inherent properties of the bedrock. The anchoring force of the anchor rods 12 within the bedrock increases the foundation's pull-out bearing capacity. The self-weight of the foundation cap 1, the friction between the outer side of the cap and the soil, and the end resistance of the rock anchor rods 12 increase the foundation's compressive bearing capacity. The end resistance of the inclined rock anchor rods 12 and the embedding of the foundation cap 1 into the rock increase the horizontal force bearing capacity, ensuring sufficient bearing capacity of the foundation. This reduces the cost of foundation engineering, facilitates construction, and shortens the construction period for the integrated construction of the photovoltaic support 2 steel column 21 and the foundation. It is not only very suitable for mountain photovoltaic power station projects with complete exposed bedrock, but also adaptable to different geological conditions.

[0064] Example 3

[0065] This embodiment is a practical application of a frustum-shaped foundation for a photovoltaic support system in a rocky area in a mountainous photovoltaic power station in South China.

[0066] Specifically, in a section of the mountain photovoltaic power station, a large area of ​​intact bedrock is exposed. A frustum-shaped foundation platform is used. The outer diameter of the top of foundation platform 1 is 426mm, the outer diameter of the bottom is 577mm, the rock embedment depth is 100mm, and the diameter of the anchor bolts is... The anchor bolt has a horizontal inclination angle of 77°, and the total height of foundation cap 1 is 500mm (excluding the length of the anchor bolt).

[0067] In the description of this invention, it should be understood that the terms "upper", "lower", "bottom", "top", "front", "rear", "inner", "outer", "left", "right", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0068] While the invention has been described herein with reference to specific embodiments, it should be understood that these embodiments are merely examples of the principles and applications of the invention. Therefore, it should be understood that many modifications can be made to the exemplary embodiments, and other arrangements can be designed without departing from the spirit and scope of the invention as defined by the appended claims. It should be understood that different dependent claims and features described herein can be combined in ways different from those described in the original claims. It is also understood that features described in conjunction with individual embodiments can be used in other described embodiments.

Claims

1. A design method for a frustum-shaped foundation for a photovoltaic support system in rocky areas, characterized in that, Includes the following steps: Step S1: Determine the implementation area; Step S2: Obtain the standard values ​​of the downward force P, upward force T, horizontal force V, and bending moment M acting on the frustum-shaped foundation; Step S3: Based on the structure of the photovoltaic support and the magnitude of the load acting on the frustum-shaped foundation, and in conjunction with the design specifications of the foundation platform and anchor rods, determine the initial parameters of the frustum-shaped foundation. Convert the bending moment M into the tensile or pull-out axial force borne by the anchor rods. Determine the inclination angle, size, and anchoring depth of the anchor rods based on the magnitude of the force. Then, determine the size of the foundation platform based on the inclination angle of the anchor rods. Combine the minimum spacing requirements of the anchor rods and the minimum size requirements of the foundation platform to obtain the initial parameters of the frustum-shaped foundation. Step S4: Calculate the comprehensive bearing capacity of the frustum foundation based on the initial parameters of the frustum foundation. Calculate the pull-out bearing capacity Ta of the foundation cap based on the self-weight of the foundation cap and the pull-out force of the rock anchor. Calculate the horizontal bearing capacity Va of the foundation cap based on the earth pressure in the active and passive zones of the foundation cap and the shear force of the anchor. Calculate the compressive bearing capacity Pa of the foundation cap based on the outer skin friction of the foundation cap and the end resistance of the anchor. Calculate the flexural bearing capacity Ma of the foundation cap based on its bending force. Step S5: Based on the comprehensive bearing capacity of the frustum foundation, verify the parameters of the frustum foundation, and compare the magnitudes of the tensile bearing capacity Ta and the standard value of the uplift force T, the horizontal bearing capacity Va and the standard value of the horizontal force V, the compressive bearing capacity Pa and the standard value of the downward force P, and the bending bearing capacity Ma and the standard value of the bending moment M. The design of the frustum-shaped anchor rod is completed only when T≤Ta, V≤Va, P≤Pa, and M≤Ma occur simultaneously. If the verification fails, the design parameters of the frustum foundation shall be adjusted and the verification shall be performed again. If the verification is successful, the design of the frustum-shaped foundation is complete.

2. The design method for a frustum-shaped foundation for a photovoltaic support in rocky areas according to claim 1, characterized in that, Step S1 includes: The area of ​​multiple intact bedrocks exposed on the surface of the project area is obtained and classified according to their area size. At the same time, the thickness of the shallow soil layer of each intact bedrock is obtained, and the area with a shallow soil layer thickness of less than 300mm and a large area of ​​intact bedrock is selected as the implementation area.

3. The design method for a frustum-shaped foundation for a photovoltaic support in rocky areas according to claim 1, characterized in that, Step S2 includes: The structural form of the photovoltaic support is obtained, and its structure is calculated and analyzed according to multiple loads to obtain the standard values ​​of the downward force P, upward force T, horizontal force V, and bending moment M acting on the frustum-shaped foundation. The multiple loads include engineering wind load, snow load, the self-weight load of the photovoltaic support, and seismic action.

4. A structure for a frustum-shaped foundation for a photovoltaic support system in rocky areas, employing the design method for a frustum-shaped foundation for a photovoltaic support system in rocky areas as described in any one of claims 1 to 3, characterized in that... It includes a foundation platform with a frustum-shaped structure and anchor rods anchored into the foundation rock in an inclined state. The steel column of the photovoltaic support is inserted into the foundation platform, and the anchor rod is connected to the steel column. The anchor rod is set in the foundation platform and is integrally cast with the foundation platform.

5. The structure of a frustum-shaped foundation for a photovoltaic support in rocky areas according to claim 4, characterized in that, The foundation cap is also equipped with a reinforcing frame, which includes reinforcing steel bars extending vertically and horizontally.

6. The structure of a frustum-shaped foundation for a photovoltaic support in rocky areas according to claim 5, characterized in that, The anchor bolts are evenly spaced along the circumference of the steel column.

7. The structure of a frustum-shaped foundation for a photovoltaic support in rocky areas according to claim 4, characterized in that, The bottom of the foundation platform is embedded in the foundation rock.

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