Method for calculating anti-overturning bearing capacity of electric pole with assembly type foundation

Abstract

The invention relates to a method for calculating the anti-overturning bearing capacity of an electric pole with an assembly type foundation, and belongs to the technical field of power grid operation and maintenance, and the method comprises the steps: 1, obtaining the data of an electric pole body, and calculating the anti-overturning ultimate bearing capacity F1 of the electric pole body; 2, data of the fabricated foundation are obtained, and the anti-overturning ultimate bearing capacity F2 of the fabricated foundation is calculated; and 3, according to the F1, the F2 and the interaction coefficients corresponding to the F1 and the F2, the overall anti-overturning ultimate bearing capacity F of the electric pole body and the assembly type foundation is calculated. Scientific reference is provided for the electric pole with the assembly type foundation, and design of the electric pole with the assembly type foundation can be assisted.

Description

Technical Field

[0001] The invention relates to a method for calculating the anti-overturning bearing capacity of an electric pole with an assembled foundation, and belongs to the technical field of power grid operation and maintenance. Background Art

[0002] Electric poles can collapse or overturn under the influence of extremely bad weather conditions, such as typhoon weather, and the collapse or overturning of electric poles can cause serious power accidents such as line short circuits and interruptions. The collapse of electric poles on both sides of the road also hinders road traffic.

[0003] In order to avoid overturning and falling of poles due to insufficient bearing capacity of pole foundations in extreme weather, thus causing immeasurable damage to the power grid, the current solution is to install a prefabricated foundation at the bottom of the pole to increase the stability and anti-overturning strength of the pole. However, there is currently no research on the anti-overturning bearing capacity of poles with prefabricated foundations.

[0004] A method for calculating the collapse load of power towers against disaster weather is disclosed in a Chinese invention patent with publication number CN105488732A. The specific steps include collecting data on natural disasters at construction sites of power towers, constructing an extreme value distribution function, calculating the minimum load of power towers against disasters, the total load against natural disasters and selecting data.

[0005] In the calculation steps of the above reference example, the supporting effect of the prefabricated foundation on the pole is not taken into account. Therefore, the calculation of the anti-overturning bearing capacity of the pole with a prefabricated foundation is inaccurate and the error is large. It cannot provide a reference for the pole with a prefabricated foundation, so improvement is urgently needed. Summary of the invention

[0006] In order to overcome the shortcomings of the above-mentioned prior art, the present invention designs a method for calculating the anti-overturning bearing capacity of an electric pole with an assembled foundation, which provides a scientific reference for the electric pole with an assembled foundation and can assist in the design of the electric pole with an assembled foundation.

[0007] In order to achieve the above object, the present invention adopts the following technical solution:

[0008] A method for calculating the anti-overturning bearing capacity of an electric pole with an assembled foundation comprises the following steps:

[0009] Step 1: Obtain the data of the pole body and calculate the ultimate anti-overturning bearing capacity F of the pole body 1 ;

[0010] Step 2: Obtain the data of the prefabricated foundation and calculate the ultimate bearing capacity F of the prefabricated foundation 2 ;

[0011] Step 3: According to F 1 、F2 and F 1 and F 2 The corresponding interaction coefficients are used to calculate the ultimate anti-overturning bearing capacity F of the pole body and the assembled foundation as a whole.

[0012] Furthermore, in step 1, assuming that the soil reaches a limit equilibrium state,

[0013] Among them, m is the soil parameter pressure;

[0014] b 0 =bk 0 , where b is the actual width of the pole body, k 0 is the space enlargement coefficient;

[0015] h t is the buried depth of the pole body;

[0016] Among them, H 0 It is the distance from the point of action of the horizontal force on the upper part of the pole body to the designed ground;

[0017]

[0018] Furthermore, in step 2, the assembled foundation includes a cap and a plurality of pile foundations vertically fixed to the bottom of the cap and buried underground, then F 2 =nη h R ha , where n is the number of piles, R ha is the characteristic value of the horizontal bearing capacity of a single pile, η h is the comprehensive effect coefficient.

[0019] Furthermore, the comprehensive effect coefficient η h The calculation formula is:

[0020] η h =η i η r +η b +η l ;

[0021] η i is the mutual influence effect coefficient of pile foundation;

[0022] η r is the constraint effect coefficient at the top of the pile foundation;

[0023] η l is the horizontal resistance effect coefficient of the lateral soil of the cap;

[0024] η bis the friction effect coefficient of the bottom surface of the cap.

[0025] Furthermore, when the cap is placed on the ground and the side of the cap is not covered with soil, the friction effect coefficient η of the bottom surface of the cap is ignored. b and the horizontal resistance effect coefficient η of the lateral soil of the cap l .

[0026] Furthermore, the mutual influence effect coefficient η of the pile foundation is i The calculation formula is:

[0027]

[0028] Among them, S a / d is the ratio of the center distance of the pile foundation along the direction of horizontal load to the pile diameter of the pile foundation;

[0029] n 1 is the number of piles in each row of pile foundation along the direction of horizontal load action;

[0030] n 2 The number of piles in each row of pile foundation along the direction perpendicular to the horizontal load.

[0031] Furthermore, the horizontal bearing capacity characteristic value R of the single pile ha The calculation formula is:

[0032]

[0033] Among them, EI is the bending stiffness of the pile body of the pile foundation;

[0034] α is the pile-soil deformation coefficient of the pile foundation;

[0035] v x is the horizontal displacement coefficient of the pile top of the pile foundation;

[0036] χ oa It is the allowable value of horizontal displacement of pile top in pile foundation.

[0037] Furthermore, when the bending strength of the pile foundation is used to control χ oa When the value of is oa The calculation formula is:

[0038] Furthermore, in step 3, the calculation formula of F is: F = 0.8k 1 F 1 +0.6k 2 k 3 k 4 F 2 ;

[0039] The interaction coefficients include:

[0040] k 1 is the factor that affects the bearing capacity of the pole body by the pile length of the pile foundation;

[0041] k 2 is the influencing factor of the pile length of the pile foundation on the bearing capacity of the prefabricated foundation;

[0042] k 3 is the influencing factor of the buried depth of the pole body on the bearing capacity of the assembled foundation;

[0043] k 4 It is the influencing factor of the increase of the base size on the bearing capacity of the prefabricated foundation.

[0044] Further, in step 1, S j The following formula must be met:

[0045] S j ≥γ f S 0 , and M j ≥γ f H 0 S 0 ;

[0046] Among them, M i is the ultimate overturning moment of the pole body;

[0047] γ f is the additional sub-item coefficient;

[0048] S 0 It is the horizontal force acting on the upper part of the pole body located on the ground.

[0049] Compared with the prior art, the present invention has the following characteristics and beneficial effects:

[0050] The present invention calculates the anti-overturning ultimate bearing capacity of the pole body and the assembled foundation, simplifies the bearing capacity of the assembled foundation pole into two bearing parts, and takes the stress of the soil around the pole body reaching the limit state as the standard to carry out corresponding calculation research, and finally obtains the ultimate bearing capacity of the pole with the assembled foundation through correction, which has high accuracy and good applicability, meets the engineering requirements, embodies the accuracy and applicability of the calculation method, is used for the calculation of the anti-overturning bearing capacity of the assembled foundation of the pole, and provides corresponding technical support for the new foundation form. DETAILED DESCRIPTION

[0051] The present invention is described in more detail below with reference to the embodiments.

[0052] The method for calculating the anti-overturning bearing capacity of the assembled foundation pole of this embodiment includes the following steps:

[0053] Step 1: Obtain the data of the pole body and calculate the ultimate anti-overturning bearing capacity F of the pole body 1 ;

[0054] Step 2: Obtain the data of the prefabricated foundation and calculate the ultimate bearing capacity F of the prefabricated foundation 2 ;

[0055] Step 3: According to F 1 、F 2 and F 1 and F 2 The corresponding interaction coefficients are used to calculate the ultimate anti-overturning bearing capacity F of the pole body and the assembled foundation as a whole.

[0056] Specifically, in step 1, assuming that the soil reaches a limit equilibrium state, then

[0057] Among them, m is the soil parameter pressure;

[0058] b 0 =bk 0 , where b is the actual width of the pole body, k 0 is the space enlargement coefficient;

[0059] h t is the buried depth of the pole body;

[0060] Among them, H 0 It is the distance from the point of action of the horizontal force on the upper part of the pole body to the designed ground;

[0061] where θ is given by the equation Sure;

[0062] At the same time, θ can also be determined as shown in Table 1 below.

[0063] η θ μ η·μ η θ μ η·μ 0.10 0.784 82.9 8.3 5.00 0.720 11.8 59.1 0.25 0.774 41.3 10.4 6.00 0.718 11.6 69.0 0.50 0.761 25.3 12.7 7.00 0.716 11.3 79.0 1.00 0.746 17.7 17.7 8.00 0.715 11.2 89.2 2.00 0.732 14.1 28.1 9.00 0.714 11.0 99.3 3.00 0.725 12.6 37.8 10.00 0.713 11.0 109.1 4.00 0.722 13.1 48.5

[0064] Table 1

[0065] At the same time, S j The following formula must be met:

[0066] S j ≥γ f S 0 , and M j ≥γ f H 0 S 0 ;

[0067] Among them, M j is the ultimate overturning moment of the pole body;

[0068] γ f is the additional sub-item coefficient;

[0069] S 0 It is the horizontal force acting on the upper part of the pole body located on the ground.

[0070] Furthermore, in step 2, the assembled foundation includes a cap and a plurality of pile foundations vertically fixed to the bottom of the cap and buried underground, then F 2 =nη h R ha , where n is the number of piles. If n=1, it is a single pile, and if n≥2, it is a group pile. ha is the characteristic value of the horizontal bearing capacity of a single pile, η h is the comprehensive effect coefficient, η h The interaction between the reaction cap and pile foundation and the soil.

[0071] In this embodiment, the pile foundation type is a steel pile, a prefabricated pile, or a cast-in-place pile with a reinforcement ratio of not less than 0.65%.

[0072] Furthermore, the comprehensive effect coefficient η h The calculation formula is:

[0073] η h =η i η r +η b +η l ;

[0074] η i is the mutual influence effect coefficient of pile foundation;

[0075] η r is the constraint effect coefficient at the top of the pile foundation;

[0076] η l is the horizontal resistance effect coefficient of the lateral soil of the cap;

[0077] η b is the friction effect coefficient of the bottom surface of the cap.

[0078] In particular, in practical applications, the cap is placed on the ground and the side of the cap is not covered with soil, so the friction effect coefficient η of the bottom surface of the cap can be ignored. b and the horizontal resistance effect coefficient η of the lateral soil of the cap l , considering only η i and η r impact.

[0079] Furthermore, the mutual influence effect coefficient η of the pile foundation i The calculation formula is:

[0080]

[0081] Among them, S a / d is the ratio of the center distance of the pile foundation along the direction of horizontal load to the pile diameter of the pile foundation;

[0082] n 1 is the number of piles in each row of pile foundation along the direction of horizontal load action;

[0083] n 2 The number of piles in each row of pile foundation along the direction perpendicular to the horizontal load.

[0084] Specifically, the constraints of the pile top of the pile foundation in the pedestal have two states: free and embedded. The free state can make the bending moment of the pile top of the pile foundation zero and the horizontal displacement slightly larger, while the embedded state can make the horizontal displacement of the pedestal smaller and the bending moment of the pile top of the pile foundation slightly larger.

[0085] Therefore, η r The values ​​of displacement control and bending control are shown in Table 2 below:

[0086] Conversion depth αh 2.4 2.6 2.8 3.0 3.5 ≥4.0 Displacement control 2.58 2.34 2.20 2.13 2.07 2.05 Intensity Control 1.44 1.57 1.71 1.82 2.00 2.07

[0087] Table 2

[0088] Furthermore, the horizontal bearing capacity characteristic value R of the single pile ha The calculation formula is:

[0089]

[0090] Among them, EI is the bending stiffness of the pile body of the pile foundation;

[0091] α is the pile-soil deformation coefficient of the pile foundation;

[0092] v x is the horizontal displacement coefficient of the pile top of the pile foundation;

[0093] Specifically, v x Please select from Table 3:

[0094]

[0095] Table 3

[0096] χ oa is the allowable value of the horizontal displacement of the pile top of the pile foundation, and the displacement of the pile foundation is used to control the oa The value of .

[0097] Furthermore, χ oa There are two control criteria, namely the displacement of the pile foundation and the bending strength of the pile foundation. When the bending strength of the pile foundation is used to control χ oa When the value of is oa The calculation formula is:

[0098]

[0099] In particular, in Table 2 and Table 3, the converted depth αh is the converted depth of the pile length of the pile foundation, specifically:

[0100]

[0101] Among them, b p is the calculated width of the pile foundation;

[0102] m is the proportional coefficient of foundation coefficient along the depth, kN / m 4 ;

[0103] h is the length of the pile foundation.

[0104] Furthermore, in step 3, the calculation formula of F is: F = 0.8k 1 F 1 +0.6k 2 k 3 k 4 F 2 ;

[0105] The interaction coefficients include:

[0106] k 1 is the factor that affects the bearing capacity of the pole body by the pile length of the pile foundation;

[0107] k 2 is the influencing factor of the pile length of the pile foundation on the bearing capacity of the prefabricated foundation;

[0108] k 3 is the influencing factor of the buried depth of the pole body on the bearing capacity of the assembled foundation;

[0109] k 4 is the influencing factor of the increase of the cap size on the bearing capacity of the prefabricated foundation;

[0110] Specifically, as shown in Table 4 below, the interaction coefficient is obtained by numerical simulation:

[0111]

[0112] Table 4.

[0113] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the term "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0115] Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

Claims

1. A method for calculating the anti-overturning bearing capacity of an electric pole with an assembled foundation, characterized in that: The steps include: Step 1, obtaining the data of the pole body and calculating the anti-overturning ultimate bearing capacity F1 of the pole body; Step 2, obtaining the data of the prefabricated foundation and calculating the anti-overturning ultimate bearing capacity F2 of the prefabricated foundation; Step 3: Calculate the ultimate anti-overturning bearing capacity F of the pole body and the assembled foundation as a whole according to F1, F2 and the interaction coefficients corresponding to F1 and F2.

2. The method for calculating the anti-overturning bearing capacity of a pole with an assembled foundation according to claim 1 is characterized in that: In step 1, it is assumed that the soil has reached a limit equilibrium state. Among them, m is the soil parameter pressure; b0=bk0, where b is the actual width of the pole body and k0 is the space enlargement coefficient; h t is the buried depth of the pole body; Where H0 is the distance from the point of action of the horizontal force on the upper part of the pole body to the designed ground; 3. The method for calculating the anti-overturning bearing capacity of a pole with an assembled foundation according to claim 2 is characterized in that: In step 2, the assembled foundation includes a cap and a plurality of pile foundations vertically fixed to the bottom of the cap and buried underground, then F2 = nη h R ha , where n is the number of piles, R ha is the characteristic value of the horizontal bearing capacity of a single pile, η h is the comprehensive effect coefficient.

4. The method for calculating the anti-overturning bearing capacity of a pole with an assembled foundation according to claim 3 is characterized in that: The comprehensive effect coefficient η h The calculation formula is: or h =the i or r +n b +n l ; η i is the mutual influence effect coefficient of pile foundation; η r is the constraint effect coefficient at the top of the pile foundation; η l is the horizontal resistance effect coefficient of the lateral soil of the cap; η b is the friction effect coefficient of the bottom surface of the cap.

5. The method for calculating the anti-overturning bearing capacity of a pole with an assembled foundation according to claim 4 is characterized in that: When the cap is placed on the ground and the side of the cap is not covered with soil, the friction effect coefficient η of the bottom surface of the cap is ignored. b and the horizontal resistance effect coefficient η of the lateral soil of the cap l .

6. The method for calculating the anti-overturning bearing capacity of a pole with an assembled foundation according to claim 4 is characterized in that: The mutual influence effect coefficient η of the pile foundation i The calculation formula is: Among them, S a / d is the ratio of the center distance of the pile foundation along the direction of horizontal load to the pile diameter of the pile foundation; n1 is the number of piles in each row of pile foundation along the direction of horizontal load action; n2 is the number of piles in each row of pile foundation along the direction of vertical horizontal load.

7. The method for calculating the anti-overturning bearing capacity of a pole with an assembled foundation according to claim 3 is characterized in that: The characteristic value of the horizontal bearing capacity of a single pile R ha The calculation formula is: Among them, EI is the bending stiffness of the pile body of the pile foundation; α is the pile-soil deformation coefficient of the pile foundation; v x is the horizontal displacement coefficient of the pile top of the pile foundation; χ oa It is the allowable value of horizontal displacement of pile top in pile foundation.

8. The method for calculating the anti-overturning bearing capacity of a pole with an assembled foundation according to claim 7 is characterized in that: When the bending strength of the pile foundation is used to control X oa When the value of oa The calculation formula is:

9. The method for calculating the anti-overturning bearing capacity of a pole with an assembled foundation according to claim 1 is characterized in that: In step 3, the calculation formula of F is: F=0.8k1F1+0.6k2k3k4F2; The interaction coefficients include: k1 is the factor that affects the pile length of the pile foundation on the bearing capacity of the pole body; k2 is the influencing factor of the pile length of the pile foundation on the bearing capacity of the prefabricated foundation; k3 is the influencing factor of the buried depth of the pole body on the bearing capacity of the assembled foundation; k4 is the influencing factor of the increase in the size of the pedestal on the bearing capacity of the prefabricated foundation.

10. The method for calculating the anti-overturning bearing capacity of a pole with an assembled foundation according to claim 2 is characterized in that: In step 1, S j The following formula must be met: S j ≥γ f S0, and M j ≥γ f H0S0; Among them, M j is the ultimate overturning moment of the pole body; γ f is the additional sub-item coefficient; S0 is the horizontal force acting on the upper part of the pole body on the ground.

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