A calculation method applied to a micro pile foundation of a photovoltaic support structure

Abstract

The application provides a kind of applied to photovoltaic support structure micropile foundation calculation method, it is related to new energy equipment field, including: obtaining the vertical ultimate bearing capacity standard value Q Muk Of micropile, the vertical compressive bearing capacity of micropile is calculated according to Q Muk ; Corresponding to the standard combination of action, the horizontal force H MiK Acting on the top of micropile is obtained, the vertical uplift bearing capacity of micropile is calculated according to H MiK ; Confirm the horizontal load characteristic value of micropile and the overall stability of micropile against overturning;The structural strength of micropile is judged based on the vertical compressive bearing capacity of micropile, the vertical uplift bearing capacity of micropile, the horizontal load characteristic value of micropile and the overall stability of micropile against overturning, the application discloses a kind of applied to photovoltaic support structure micropile foundation calculation method.The method overcomes the shortcomings of long pile length caused by the existing calculation method, which causes engineering waste.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of new energy equipment, in particular to a calculation method applied to a micro pile foundation of a photovoltaic support structure. BACKGROUND

[0002] The photovoltaic support structure is firm and reliable, can withstand atmospheric corrosion, wind load and other external effects, can achieve maximum use effect with minimum installation cost, has reliable maintenance, and meanwhile, factors such as cost reasonableness are considered. The selection and design of a good stable and low-cost foundation are key components of the entire structure design.

[0003] The micro pile foundation system has the advantages of large overall rigidity, small pile top displacement, and automatic adjustment of the internal force of the structure itself to maintain stability and safety under complex and variable external loads. When the bending stiffness of the cantilever support single pile cannot meet the deformation control requirements due to large excavation depth or weak soil layer, the cold-bending thin-walled steel system of the pile foundation is often used. In the existing calculation method, the overturning safety factor of the calculated pile structure is often small, which does not meet the requirements of the specification, and the length of the micro pile needs to be increased, while the overturning damage of the micro pile is very rare in actual engineering. Therefore, in order to meet the requirements of the specification, the length of the pile needs to be increased in the calculation method of the overall anti-overturning stability safety factor of the micro pile foundation in the existing technology, which causes waste. SUMMARY

[0004] The purpose of the present application is to provide a calculation method applied to a micro pile foundation of a photovoltaic support structure, which can more accurately calculate the overall anti-overturning stability safety factor of the micro pile.

[0005] In order to achieve the above-mentioned purpose, the present application provides the following technical scheme: a calculation method applied to a micro pile foundation of a photovoltaic support structure, comprising: obtaining a vertical ultimate bearing capacity standard value Q Muk of the micro pile, calculating a vertical compression bearing capacity of the micro pile according to Q Muk ; obtaining a horizontal force H MiK acting on the pile top of the micro pile corresponding to the standard combination of actions, calculating a vertical uplift bearing capacity of the micro pile according to H MiK ; confirming a horizontal load characteristic value of the micro pile and an overall anti-overturning stability of the micro pile; and judging the structural strength of the micro pile based on the vertical compression bearing capacity of the micro pile, the vertical uplift bearing capacity of the micro pile, the horizontal load characteristic value of the micro pile and the overall anti-overturning stability of the micro pile.

[0006] Further, the vertical compression bearing capacity of the micro pile comprises: a pile top average vertical force N Mk, the maximum vertical force N at the pile top of the micro pile under the standard combination of load effect and eccentric vertical force Mkmax , the average vertical force N at the pile top of the micro pile under the standard combination of seismic effect and load effect MEk , the maximum vertical force N at the pile top of the micro pile under the standard combination of seismic effect and load effect MEkmax ;

[0007] wherein,

[0008] N Mk ≤ R (1)

[0009] N Mkmax ≤ 1.2R (2)

[0010] N MEk ≤ 1.25R (3)

[0011] N Mkmax ≤ 1.5R (4)

[0012] R = Q Muk / K (5)

[0013] R is the single-pile vertical compressive ultimate bearing capacity characteristic value of the micro pile, and K is a safety factor.

[0014] Further, Q Muk = Q Msk + Q Mpk (6)

[0015] wherein, the Q Msk is the total ultimate side resistance of the micro pile, and the Q Mpk is the total ultimate end resistance standard value of the micro pile.

[0016] Further,

[0017] Q Msk = u∑ qsik l i (7)

[0018] wherein, q sik is the ultimate side resistance standard value of the i-th layer of soil around the micro pile estimated by the static sounding specific penetration resistance value, l i is the thickness of the i-th layer of soil around the micro pile, and u is the circumference of the micro pile.

[0019] Q Mpk = q pk A p (8)

[0020] wherein, q pkis a standard value of the ultimate end resistance of the micropile, and Ap is an area of a pile end of the micropile.

[0021] Further, a vertical uplift bearing capacity of the micropile

[0022] wherein T uk is a standard value of the ultimate vertical uplift bearing capacity of the micropile, N k is a base pile uplift force of the micropile calculated by load standard combination, G p is a self-weight of the micropile, when the micropile has a portion located below a groundwater level, G p is a buoyant weight of the micropile.

[0023] Further, a horizontal load characteristic value R Ha ≥ H MiK of the micropile.

[0024] wherein H Mik is a horizontal force acting on a pile top of the micropile corresponding to an acting standard combination.

[0025] Further, an overall anti-overturning stability of the micropile is determined by an ultimate overturning force S j of the micropile and an ultimate overturning moment M j of the micropile.

[0026]

[0027]

[0028] wherein m is a soil pressure parameter weighted value of the micropile, b0 is a calculation width of a pile foundation of the micropile, h t is a buried depth of the micropile, γ f is a basic additional partial coefficient determined by an environment of the micropile, S0 is a horizontal force design value of the micropile, μ is an ultimate overturning bearing coefficient of the micropile, H0 is a pile foundation ground level height of the micropile, and η is a ratio of a distance of a horizontal acting force of a pile top of the micropile from a design ground level to a buried depth of the micropile foundation.

[0029] Further,

[0030]

[0031]

[0032] b0 = bK0 (14)

[0033]

[0034] wherein, θ is the included angle between the foundation pressure diffusion line and the vertical line, K0 is the space increase coefficient of the pile foundation of the micro pile, m i is the soil pressure parameter of the i th soil layer where the micro pile is located, h i is the buried depth of the i th soil layer where the micro pile foundation is located, b is the actual width of the pile foundation of the micro pile.

[0035] Further,

[0036]

[0037] wherein, β is the equivalent internal friction angle weighted value of the micro pile, ξ is the lateral pressure coefficient weighted value of the soil where the micro pile is buried.

[0038] Further,

[0039]

[0040]

[0041] wherein, the β i is the equivalent internal friction angle of the i th soil layer where the micro pile is located, the ξ i is the lateral pressure coefficient of the i th soil layer where the micro pile is located.

[0042] It can be analyzed that the application discloses a calculation method applied to a micro pile foundation of a photovoltaic support structure, analyzes and deduces corresponding model stress conditions and analytic formulas. The method overcomes the defects of long pile length caused by the existing calculation method and causes engineering waste. The micro pile foundation structure mechanical performance and stability parameters calculated by the application supplement the calculation content in the prior art, and more safe and effective design results can be obtained. BRIEF DESCRIPTION OF DRAWINGS

[0043] The drawings accompanying the specification provide further understanding of the application, and the illustrative embodiments thereof, together with explanations, serve to explain the application, and do not constitute an improper limitation on the application. Among them:

[0044] Figure 1 The stress calculation diagram of an embodiment of the application.

[0045] Figure 2 The stress schematic diagram of the foundation vertical compression of the micro pile of an embodiment of the application.

[0046] Figure 3 The stress-displacement relationship diagram of the micro pile of an embodiment of the application. DETAILED DESCRIPTION

[0047] The present application will be described in detail below with reference to the attached drawings and embodiments. Various examples are provided by way of explanation of the present application and are not intended to limit the present application. In fact, those skilled in the art will appreciate that modifications and variations to the present application can be made without departing from the spirit or scope of the application. For example, features shown or described as part of one embodiment can be used in another embodiment to yield still a further embodiment. It is therefore intended that the present application encompass such modifications and variations as come within the scope of the appended claims and their equivalents.

[0048] In the description of the present application, the terms "longitudinal", "transverse", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", and the like indicate the orientation or positional relationship shown in the drawings based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and do not require the present application to be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application. The terms "connected", "connected", "provided" used in the present application should be understood broadly, for example, it can be fixedly connected or detachably connected; it can be directly connected or indirectly connected through an intermediate part; it can be wired electrically connected, wirelessly electrically connected, or wirelessly communicated, and the specific meaning of the above terms can be understood by those skilled in the art according to the specific circumstances.

[0049] One or more examples of the present application are shown in the accompanying drawings. The detailed description uses numerical and letter designations to refer to features in the drawings. Like or similar designations in the drawings and description have been used to label like or similar parts of the present application. As used herein, the terms "first", "second", "third", and "fourth" and the like can be used interchangeably to distinguish one component from another and are not intended to signify location or importance of the individual components.

[0050] As shown in Figure 1 According to an embodiment of the present application, a calculation method applied to a photovoltaic support structure micro pile foundation is provided, the micro pile generally refers to a cast-in-place pile with a pile diameter less than 400mm, a slenderness ratio greater than 30, and a drilling, strong reinforcement and pressure grouting construction process, comprising:

[0051] Obtaining the standard value Q of the vertical ultimate bearing capacity of the micro pile Muk , calculating the vertical compressive bearing capacity of the micro pile according to Q Muk ;

[0052] Obtaining the horizontal force H acting on the top of the micro pile corresponding to the standard combination of the action MiK , calculating the vertical uplift bearing capacity of the micro pile according to H MiK ;

[0053] Confirm the horizontal load characteristic value of the micro pile and the overall anti-overturning stability of the micro pile;

[0054] Determine the structural strength of the micro pile based on the vertical compressive bearing capacity of the micro pile, the vertical uplift bearing capacity of the micro pile, the horizontal load characteristic value of the micro pile and the overall anti-overturning stability of the micro pile.

[0055] The overall calculation diagram is shown in Figure 1 , wherein F0(H MiK ) is the design value of the horizontal bearing capacity (shear resistance), which is calculated by the actual design standard.

[0056] Preferably, the vertical compressive bearing capacity of the micro pile includes: the average vertical force N Mk at the pile top of the micro pile under the action of the load effect standard combination axial vertical force, the maximum vertical force N Mkmax at the pile top of the micro pile under the action of the load effect standard combination eccentric vertical force, the average vertical force N MEk at the pile top of the micro pile under the action of the seismic effect and the load effect standard combination, and the maximum vertical force N MEkmax at the pile top of the micro pile under the action of the seismic effect and the load effect standard combination.

[0057] , wherein,

[0058] N Mk ≤R (1)

[0059] N Mkmax ≤1.2R (2)

[0060] N MEk ≤1.25R (3)

[0061] N Mkmax ≤1.5R (4)

[0062] R=Q Muk / K (5)

[0063] R is the single-pile vertical compressive ultimate bearing capacity characteristic value of the micro pile, and K is a safety factor, which is generally 2.

[0064] Preferably, Q Muk =Q Msk +Q Mpk (6)

[0065] , wherein Q Msk is the total ultimate side resistance of the micro pile, and Q Mpk is the total ultimate end resistance standard value of the micro pile.

[0066] The specific compressive analysis of the micro pile is shown in Figure 2 and Figure 3 , wherein QMαk is the static friction resistance (kN) of the micro pile, S is the displacement of the micro pile, a2 is the vertical ultimate bearing capacity standard value change curve of the micro pile, b2 is the vertical total ultimate side resistance standard value change curve of the micro pile, c2 is the vertical total ultimate tip resistance standard value change curve of the micro pile, ① is the vertical ultimate bearing capacity standard value of the micro pile, ② is the vertical total ultimate side resistance failure point of the micro pile, and ③ is the vertical total ultimate tip resistance limit failure point of the micro pile.

[0067] Preferably, Q Msk = u∑q sik l i (7)

[0068] wherein q sik is the ultimate side resistance standard value of the i-th layer of soil around the micro pile estimated by the static sounding specific penetration resistance value of the micro pile, l i is the thickness of the i-th layer of soil around the micro pile, and u is the circumference of the micro pile.

[0069] Q Mpk = Q pk A p (8)

[0070] wherein q pk is the ultimate tip resistance standard value of the micro pile, A p is the tip area of the micro pile, and A p = (d^ 2 ) / 4, D = the diameter of the micro pile.

[0071] Preferably, the vertical uplift bearing capacity of the micro pile is

[0072] wherein T uk is the vertical uplift ultimate bearing capacity standard value of the micro pile, N k is the base pile uplift force of the micro pile calculated according to the load standard combination, G p is the self-weight of the micro pile, G p is the buoyant weight of the micro pile when the micro pile has a portion below the groundwater level.

[0073] Preferably, the horizontal load characteristic value R Ha of the micro pile is greater than H MiK .

[0074] wherein H MiK is the horizontal force acting on the top of the micro pile corresponding to the standard combination of the action.

[0075] Preferably, the overall overturning stability of the micro pile is determined by the limit overturning force S j of the micro pile and the limit overturning moment M j of the micro pile.

[0076]

[0077]

[0078] wherein m is the soil pressure parameter weighted value of the micropile, b0 is the calculated width of the pile foundation of the micropile, h t is the embedded depth of the micropile, γ f is the basis additional partial coefficient determined according to the environment of the micropile, S0 is the design value of the horizontal force of the micropile, μ is the ultimate overturning bearing coefficient of the micropile, H0 is the height of the pile foundation of the micropile out of the ground, η is the ratio of the distance of the horizontal action force at the top of the micropile to the design ground and the embedded depth of the micropile foundation, γ f is determined according to the actual environment of the pile foundation of the micropile, and b and h t are determined according to the actual situation of the design drawing; the number of soil layers where the pile foundation of the micropile is located, the groundwater depth, the unit weight γ and the saturated unit weight γb of each soil layer are determined according to the recommended values of the physical and mechanical properties of the stratum provided by the geotechnical engineering investigation, wherein the groundwater index parameters are assumed to be the related parameters of the current layer for simplified calculation. The β i and ξ i are determined according to the information of the soil name, weathering degree provided by the project geotechnical engineering investigation, and then the mi of each soil layer is calculated according to the soil pressure theory.

[0079]

[0080]

[0081] b0=bK0 (14)

[0082]

[0083] wherein θ is the included angle between the foundation pressure diffusion line and the vertical line, K0 is the space increase coefficient of the pile foundation of the micropile, m i is the soil pressure parameter of the i-th soil layer where the micropile is located, h i is the embedded depth of the i-th soil layer where the micropile foundation is located, according to the existing photovoltaic support structure design method, the value of θ can be obtained from the equation: The results are derived according to the following calculation method: let a1=1、 , and the virtual root of the discriminant is determined, let:

[0084] A=b1 2 -3a1c1, B=b1c1-9a1d1, C=c1 2 -3b1d1

[0085] , that is: Discriminant: Δ = B 2 -4AC > 0, from the above, its total discriminant has one real root and two unequal imaginary roots:

[0086]

[0087]

[0088]

[0089] Y1 = Ab1 + 1.5a1 Y2 = Ab1 + 1.5a1

[0090] Here, the real root x1 is retained as the solution of θ value.

[0091] Preferably,

[0092] Wherein, β is the equivalent internal friction angle weighting value of the micro pile, ξ is the soil lateral pressure coefficient weighting value received by the micro pile, and b is the actual width of the pile foundation of the micro pile.

[0093] Preferably,

[0094]

[0095] Wherein, β i is the equivalent internal friction angle of the i-th soil layer where the micro pile is located, and ξ i is the soil lateral pressure coefficient of the i-th soil layer where the micro pile is located.

[0096] Taking the actual situation of a certain project as an example, Table 1 is the performance table of the soil layer where the micro pile is located, and the design parameters of the micro pile are as follows: the actual width of the pile foundation of the micro pile b = 250 mm, the design value of the horizontal force S0 = 4.420 kN, the environmental determination basis additional partial coefficient of the micro pile γf = 1.10, the height of the pile foundation of the micro pile out of the ground H0 = 0.60 m, the buried depth of the micro pile ht = 1.500 m, the number of soil layers is 1, and the groundwater depth is -10.000 m. Through Table 2, the horizontal shear and overturning stability of the micro pile of the project can be obtained.

[0097] Table 1 Performance table of soil layer

[0098] Layer number Layer thickness Density Saturated density Equivalent internal friction Earth side pressure Earth pressure parameter (m) (kN / m 3 )]]> (kN / m 3 )]]> Resistance angle β (°) Force coefficient ξ m(kN / m 3 )]]> 1 5.00 19.00 —— 30.0 0.60 57.00

[0099] Table 2 Comparison table of horizontal shear and overturning stability of micro pile

[0100] —— Horizontal shear (kN) Anti-overturning stability (kN) Horizontal force bearing value / limit overturning force standard value 4.889 4.862 Additional sub-horizontal force 4.420 5.289 Conclusion Satisfy Not satisfy

[0101] Compared with the prior art, the application of the application proposes a calculation method applied to the micro pile foundation of the photovoltaic support structure, and analyzes and deduces the corresponding model stress condition and analytical formula. The method overcomes the defect that the pile length is too long and causes engineering waste caused by the existing calculation method. The mechanical properties and stability parameters of the micro pile foundation structure calculated by the application supplement the calculation content in the prior art, and a more safe and effective design result can be obtained.

[0102] The above only describes the preferred embodiments of the application and is not intended to limit the application. For those skilled in the art, the application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. within the spirit and principle of the application shall be included in the protection scope of the application.

Claims

1. A calculation method for micropile foundations applied to photovoltaic support structures, characterized in that, include: Obtain the standard value Q of the vertical ultimate bearing capacity of the micropile. Muk According to Q Muk The vertical compressive bearing capacity of the micropiles was calculated; When the standard combination of forces is obtained, the horizontal force H acting at the top of the micropile is obtained. Mik According to H Mik The vertical pull-out bearing capacity of the micropiles was calculated; Confirm the horizontal load characteristic value of the micropile and the overall overturning stability of the micropile; The structural strength of the micropile is determined based on its vertical compressive bearing capacity, vertical tensile bearing capacity, horizontal load characteristic value, and overall overturning stability.

2. The calculation method for micropile foundations applied to photovoltaic support structures according to claim 1, characterized in that, The vertical compressive bearing capacity of the micropile includes: the average vertical force N at the top of the micropile under the action of the axial vertical force of the standard combination of load effects. Mk The maximum vertical force N at the top of the micropile under the standard combination of load effects and eccentric vertical force. Mkmax The average vertical force N at the top of the micropile under the standard combination of seismic action effect and load effect. MEk The maximum vertical force N at the top of the micropile under the standard combination of seismic action effect and load effect. MEkmax ; in, H Mk ≤R (1) N Mkmax ≤1.2R (2) Q MEk ≤1.25R (3) N MEkmax ≤1.5R (4) R=Q Muk / K(5) R is the characteristic value of the vertical compressive ultimate bearing capacity of a single micropile, and K is the safety factor.

3. The calculation method for micropile foundations applied to photovoltaic support structures according to claim 2, characterized in that, Q Muk =Q Msk +Q Mpk (6) Wherein, Q Msk Q represents the total ultimate lateral resistance of the micropile. Mpk This is the standard value of the total ultimate end resistance of the micropile.

4. The calculation method for micropile foundations applied to photovoltaic support structures according to claim 3, characterized in that, Q Msk =u∑q sik l i (7) Where, q sik The standard value of the ultimate lateral resistance of the i-th layer of soil around the micropile, estimated by the static cone penetration resistance ratio, is l. i The thickness of the i-th layer of soil on the side of the micropile is given by denoted as denoted as denoted as u, and the perimeter of the micropile is given as denoted as u. Q Mpk =q pk A p (8) Where, q pk Ap is the standard value of the ultimate end resistance of the micropile, and Ap is the end area of ​​the micropile.

5. The calculation method for micropile foundations applied to photovoltaic support structures according to claim 1, characterized in that, Vertical uplift bearing capacity of the micropiles Among them, T uk N is the standard value of the vertical pull-out ultimate bearing capacity of the micropile. k G is the pile pull-out force of the micropile calculated according to the standard load combination. p G represents the self-weight of the micropillar, and when the micropillar has a portion located below the groundwater level. p The buoyancy weight of the micropile is given.

6. The calculation method for micropile foundations applied to photovoltaic support structures according to claim 1, characterized in that, The characteristic value of the horizontal load of the micropile is R. Ha ≥H MiK ; Among them, H MiK The horizontal force acting on the top of the micropile in accordance with the standard combination of actions.

7. The calculation method for micropile foundations applied to photovoltaic support structures according to claim 1, characterized in that, Through the ultimate overturning force S of the micropillar j and the ultimate overturning moment M of the micropile j Determine the overall overturning stability of the micropiles; Where m is the weighted value of the earth pressure parameter of the micropile, b0 is the calculated width of the micropile foundation, and h t γ represents the embedment depth of the micropiles. f An additional partial factor is determined for the environment in which the micropile is located. S0 is the design value of the horizontal force of the micropile, μ is the ultimate overturning bearing coefficient of the micropile, H0 is the height of the micropile foundation above the ground, and η is the ratio of the distance of the horizontal force at the top of the micropile from the design ground to the embedment depth of the micropile foundation.

8. The calculation method for micropile foundations applied to photovoltaic support structures according to claim 7, characterized in that, b0=bK0 (14) Where θ is the angle between the ground pressure diffusion line and the vertical line, K0 is the spatial magnification factor of the micropile foundation, and m i h is the earth pressure parameter of the i-th soil layer where the micropiles are located. i denoted as , where is the embedment depth of the i-th soil layer where the micropile foundation is located, and b is the actual width of the micropile foundation.

9. The calculation method for micropile foundations applied to photovoltaic support structures according to claim 8, characterized in that, Wherein, β is the weighted value of the equivalent internal friction angle of the micropile, and ξ is the weighted value of the lateral pressure coefficient of the soil in which the micropile is embedded.

10. The calculation method for micropile foundations applied to photovoltaic support structures according to claim 9, characterized in that, Wherein, the β i ξ is the equivalent internal friction angle of the i-th soil layer where the micropillar is located. i The soil lateral pressure coefficient of the i-th soil layer where the micropiles are located.

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