Method and device for evaluating degree of reduction in bearing capacity of power transmission tower foundation after lightning strike

Abstract

A lightning stroke effect after power transmission tower foundation bearing capacity reduction degree evaluation method and device, the method comprises the following steps: the function relationship between the wave velocity value change degree of the power transmission tower foundation before and after the lightning stroke effect and the uniaxial compressive strength change degree is established; the allowable overburden load of the power transmission tower foundation numerical model is determined, and the function relationship between the bearing capacity reduction degree of the power transmission tower foundation and the uniaxial compressive strength change degree under the action of the earthquake wave and the wind load is respectively established according to the allowable overburden load; the function relationship between the wave velocity value change degree and the bearing capacity reduction degree of the power transmission tower foundation under the action of the earthquake wave and the wind load is respectively established, and the bearing capacity reduction degree of the power transmission tower foundation after the lightning stroke effect considering the influence of the horizontal load is obtained; the final bearing capacity reduction degree of the power transmission tower foundation is determined according to the wave velocity value change degree of the actual engineering power transmission tower foundation after the lightning stroke effect. The application fully considers the influence of the horizontal load, and improves the evaluation precision of the bearing capacity reduction degree of the power transmission tower foundation after the lightning stroke effect.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power transmission tower foundation, and particularly relates to a method and device for evaluating the reduction degree of the bearing capacity of a power transmission tower foundation after lightning strike. BACKGROUND

[0002] With the continuous rise in demand for electricity, the scale and complexity of power transmission engineering construction are gradually expanding, especially in the field of long-distance power transmission and high-voltage power transmission. As an important part of power transmission engineering, the power transmission tower foundation plays an important role in maintaining the stability of the power transmission engineering. However, the power transmission tower foundation exposed to the external environment for a long time often faces threats from various natural disasters such as lightning strike, storm, earthquake, etc. Among them, lightning strike is one of the main reasons for the instability of the power transmission tower foundation. Lightning strike not only causes certain damage to it, but also reduces the bearing capacity of the power transmission tower foundation.

[0003] Although the power transmission tower foundation can continue to serve after lightning strike, the reduction in bearing capacity poses a potential safety hazard for long-term operation, which not only increases the difficulty of later maintenance and management, but also brings potential risks to the overall safe operation of the power system. At present, there is still a great deficiency in the evaluation of the bearing capacity of the tower foundation after lightning strike, and the existing evaluation methods are mostly experiential judgments, lacking scientific quantitative analysis tools, and it is difficult to comprehensively and accurately evaluate the reduction degree of the bearing capacity of the power transmission tower foundation after lightning strike. Therefore, the research on the evaluation method of the bearing capacity of the power transmission tower foundation after lightning strike has important practical significance. SUMMARY

[0004] The purpose of the present application is to overcome the above-mentioned defects and problems in the prior art, and to provide a method and device for evaluating the reduction degree of the bearing capacity of a power transmission tower foundation after lightning strike, which fully considers the influence of horizontal load, and the evaluation method is more scientific and comprehensive, and more in line with the actual situation, greatly improving the evaluation accuracy.

[0005] To achieve the above purpose, the technical solution of the present application is:

[0006] A method for evaluating the reduction degree of the bearing capacity of a power transmission tower foundation after lightning strike, comprising:

[0007] Multiple lightning tests are conducted on the power transmission tower foundation with different current intensities, and the change degree of wave velocity value of the power transmission tower foundation before and after lightning strike is measured, and uniaxial compression tests are conducted on the concrete of the power transmission tower foundation before and after lightning strike to obtain uniaxial compressive strength and uniaxial compressive strength change degree, and a functional relationship between the change degree of wave velocity value and the uniaxial compressive strength change degree is established;

[0008] According to the results of multiple groups of lightning strike tests, multiple power transmission tower foundation numerical models are established, the overlying load of each power transmission tower foundation numerical model is changed until the stress value of the power transmission tower foundation numerical model reaches the corresponding load of the allowable overlying load when the uniaxial compressive strength is reached;

[0009] The allowable overlying load is applied to the top of each power transmission tower foundation numerical model, and the seismic wave is input at the bottom of the power transmission tower foundation numerical model, and the allowable overlying load is continuously reduced until the allowable overlying load corresponding to the inclination of the power transmission tower foundation numerical model reaching the threshold value under the action of the seismic wave is the first critical overlying load, the bearing capacity reduction degree of the power transmission tower foundation under the action of the seismic wave is calculated according to the first critical overlying load, and a functional relationship between the bearing capacity reduction degree of the power transmission tower foundation under the action of the seismic wave and the uniaxial compressive strength change degree is established; the allowable overlying load is applied to the top of each power transmission tower foundation numerical model, and the wind load is applied to the top of the power transmission tower foundation numerical model at the same time, and the allowable overlying load is continuously reduced until the allowable overlying load corresponding to the inclination of the power transmission tower foundation numerical model reaching the threshold value under the action of the wind load is the second critical overlying load, the bearing capacity reduction degree of the power transmission tower foundation under the action of the wind load is calculated according to the second critical overlying load, and a functional relationship between the bearing capacity reduction degree of the power transmission tower foundation under the action of the wind load and the uniaxial compressive strength change degree is established;

[0010] The functional relationship between the wave velocity value change degree and the bearing capacity reduction degree of the power transmission tower foundation under the action of the seismic wave is established according to the functional relationship between the wave velocity value change degree and the uniaxial compressive strength change degree and the functional relationship between the bearing capacity reduction degree of the power transmission tower foundation under the action of the seismic wave and the uniaxial compressive strength change degree; the functional relationship between the wave velocity value change degree and the bearing capacity reduction degree of the power transmission tower foundation under the action of the wind load is established according to the functional relationship between the wave velocity value change degree and the uniaxial compressive strength change degree and the functional relationship between the bearing capacity reduction degree of the power transmission tower foundation under the action of the wind load and the uniaxial compressive strength change degree; the bearing capacity reduction degree of the power transmission tower foundation after lightning strike considering the influence of horizontal load is obtained according to the functional relationship between the wave velocity value change degree and the bearing capacity reduction degree of the power transmission tower foundation under the action of the seismic wave and the functional relationship between the wave velocity value change degree and the bearing capacity reduction degree of the power transmission tower foundation under the action of the wind load;

[0011] The wave velocity value change degree of the power transmission tower foundation after lightning strike in the actual project is obtained, and the final bearing capacity reduction degree of the power transmission tower foundation after lightning strike is determined according to the bearing capacity reduction degree of the power transmission tower foundation after lightning strike considering the influence of horizontal load.

[0012] The multiple power transmission tower foundation numerical models are established according to the results of multiple groups of lightning strike tests, including:

[0013] The unit numerical model is established in the discrete element software PFC to simulate the uniaxial compression test, and the mesoscopic parameters under each lightning test are determined by comparing and calibrating the uniaxial compression test curves and uniaxial compressive strength of the lightning-affected power transmission tower foundation concrete in multiple groups of lightning tests;

[0014] The numerical model of various power transmission tower foundations is established, and the determined mesoscopic parameters under each lightning test are assigned to the particles and contacts of each power transmission tower foundation numerical model established.

[0015] The bearing capacity reduction degree of the power transmission tower foundation under the action of the seismic wave is ΔF i e is:

[0016]

[0017] In the formula, F0 is the engineering design load of the power transmission tower foundation; F i e is the i th first critical overburden load;

[0018] The bearing capacity reduction degree of the power transmission tower foundation under the action of the wind load is ΔF i w is:

[0019]

[0020] In the formula, F i w is the i th second critical overburden load.

[0021] The bearing capacity reduction degree of the power transmission tower foundation under the action of the lightning after considering the influence of the horizontal load is ΔF u is:

[0022] ΔF u ={ΔF e , ΔF w} max ;

[0023] In the formula, ΔF e is the function value of the bearing capacity reduction degree of the power transmission tower foundation under the action of the seismic wave and the uniaxial compressive strength change degree; and ΔF w is the function value of the bearing capacity reduction degree of the power transmission tower foundation under the action of the wind load and the uniaxial compressive strength change degree.

[0024] The threshold of the inclination of the power transmission tower foundation is 0.5%.

[0025] The determination of the final bearing capacity reduction degree of the power transmission tower foundation after the lightning action comprises:

[0026] Record the ratio of the total number of micro-cracks to the number of contacts of the numerical model of the power transmission tower foundation under different lightning tests when the critical overburden load is applied; the critical overburden load is {F i e , F i w} min , wherein F i e is the i th first critical overburden load, F i w is the i th second critical overburden load;

[0027] When the increasing rate r s of the ratio is greater than the increasing rate r u of the uniaxial compressive strength variation, the reduction degree adjustment coefficient β is calculated by the following formula:

[0028] β=1+(r s -r u );

[0029] The final bearing capacity reduction degree of the power transmission tower foundation after lightning action is obtained by multiplying the bearing capacity reduction degree of the power transmission tower foundation after considering the influence of horizontal load by the reduction degree adjustment coefficient.

[0030] The increasing rate r s of the ratio is:

[0031]

[0032] In the formula, α n represents the ratio of the total number of micro-cracks to the number of contacts under the n th group of lightning tests; α 1 represents the ratio of the total number of micro-cracks to the number of contacts under the 1 st group of lightning tests; I n represents the current intensity under the n th group of lightning tests, and I 1 represents the current intensity under the 1 st group of lightning tests, which increases from the first group of lightning tests to the n th group of lightning tests;

[0033] The increasing rate r u of the uniaxial compressive strength variation is:

[0034]

[0035] In the formula, Δσ n represents the uniaxial compressive strength variation under the n th group of lightning tests; Δσ 1 represents the uniaxial compressive strength variation under the 1 st group of lightning tests.

[0036] A device for evaluating the bearing capacity reduction degree of a power transmission tower foundation after lightning action, which is applied to the above-mentioned method, the device comprises:

[0037] The first calculation module is configured to perform multiple lightning strike tests on the power transmission tower foundation with different current intensities, measure the wave velocity value change degree of the power transmission tower foundation before and after lightning strike, perform uniaxial compression tests on the power transmission tower foundation concrete before and after lightning strike to obtain uniaxial compressive strength and uniaxial compressive strength change degree, and establish a functional relationship between the wave velocity value change degree and the uniaxial compressive strength change degree;

[0038] The second calculation module is configured to establish multiple power transmission tower foundation numerical models according to the multiple lightning strike test results, change the overlying load of each power transmission tower foundation numerical model until the stress value of the power transmission tower foundation numerical model reaches the allowable overlying load corresponding to the respective uniaxial compressive strength;

[0039] The third calculation module is configured to apply the allowable overlying load to the top of each power transmission tower foundation numerical model, input a seismic wave at the bottom of the power transmission tower foundation numerical model, and continuously reduce the allowable overlying load until the allowable overlying load corresponding to the inclination of the power transmission tower foundation numerical model reaching a threshold value under the action of the seismic wave is the first critical overlying load, calculate the bearing capacity reduction degree of the power transmission tower foundation under the action of the seismic wave according to the first critical overlying load, and establish a functional relationship between the bearing capacity reduction degree of the power transmission tower foundation under the action of the seismic wave and the uniaxial compressive strength change degree; apply the allowable overlying load to the top of each power transmission tower foundation numerical model, and simultaneously apply a wind load to the top of the power transmission tower foundation numerical model, and continuously reduce the allowable overlying load until the allowable overlying load corresponding to the inclination of the power transmission tower foundation numerical model reaching a threshold value under the action of the wind load is the second critical overlying load, calculate the bearing capacity reduction degree of the power transmission tower foundation under the action of the wind load according to the second critical overlying load, and establish a functional relationship between the bearing capacity reduction degree of the power transmission tower foundation under the action of the wind load and the uniaxial compressive strength change degree;

[0040] The fourth calculation module is configured to establish a functional relationship between the wave velocity value change degree and the bearing capacity reduction degree of the power transmission tower foundation under the action of the seismic wave according to the functional relationship between the wave velocity value change degree and the uniaxial compressive strength change degree and the functional relationship between the bearing capacity reduction degree of the power transmission tower foundation under the action of the seismic wave and the uniaxial compressive strength change degree; establish a functional relationship between the wave velocity value change degree and the bearing capacity reduction degree of the power transmission tower foundation under the action of the wind load according to the functional relationship between the wave velocity value change degree and the uniaxial compressive strength change degree and the functional relationship between the bearing capacity reduction degree of the power transmission tower foundation under the action of the wind load and the uniaxial compressive strength change degree; and obtain the bearing capacity reduction degree of the power transmission tower foundation after lightning strike considering the influence of horizontal load according to the functional relationship between the wave velocity value change degree and the bearing capacity reduction degree of the power transmission tower foundation under the action of the seismic wave and the functional relationship between the wave velocity value change degree and the bearing capacity reduction degree of the power transmission tower foundation under the action of the wind load;

[0041] The bearing capacity reduction degree determination module is used for obtaining the wave velocity value change degree of the power transmission tower foundation after lightning strike, and determining the final bearing capacity reduction degree of the power transmission tower foundation after lightning strike according to the bearing capacity reduction degree of the power transmission tower foundation after lightning strike considering the influence of horizontal load.

[0042] A lightning strike after power transmission tower foundation bearing capacity reduction degree evaluation device, comprising a memory and a processor;

[0043] The memory is used for storing computer program codes and transmitting the computer program codes to the processor;

[0044] The processor is used for executing the above-mentioned method according to the instructions in the computer program codes.

[0045] A computer readable storage medium, the computer readable storage medium has a computer program stored thereon, the computer program is executed by a processor to realize the above-mentioned method.

[0046] Compared with the prior art, the beneficial effects of the present application are:

[0047] In the lightning strike after power transmission tower foundation bearing capacity reduction degree evaluation method and device, the relationship between the wave velocity value change degree and the uniaxial compressive strength change degree before and after lightning strike is determined first, then the numerical simulation method is used to determine the allowable overburden load, considering that the power transmission tower foundation will also be subjected to seismic load and wind load during the service process after lightning strike, the critical overburden load is determined by adjusting the allowable overburden load based on the inclination threshold index, the bearing capacity reduction degree of the power transmission tower foundation under the influence of seismic action and wind load is further determined, and the relationship between the bearing capacity reduction degree of the power transmission tower foundation and the uniaxial compressive strength change degree is established. The method fully considers the influence of horizontal load, the evaluation method is more scientific and comprehensive, and is more in line with the actual situation, so that the evaluation precision is greatly improved. At the same time, the relationship between the wave velocity value change degree and the bearing capacity reduction degree of the power transmission tower foundation is established, the bearing capacity reduction degree of the power transmission tower foundation is calculated by measuring the wave velocity value change degree of the power transmission tower foundation after lightning strike, which has the advantages of simple operation, quickness and convenience, provides a quantitative method for lightning strike after power transmission tower foundation bearing capacity reduction degree evaluation, and has great application value for actual engineering. BRIEF DESCRIPTION OF DRAWINGS

[0048] Figure 1 It is a flow chart of the lightning strike after power transmission tower foundation bearing capacity reduction degree evaluation method.

[0049] Figure 2 It is a structural block diagram of the lightning strike after power transmission tower foundation bearing capacity reduction degree evaluation device.

[0050] Figure 3 is a structural block diagram of a lightning strike effect after power transmission tower foundation bearing capacity reduction degree evaluation device. DETAILED DESCRIPTION

[0051] The application is further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0052] Reference Figure 1 , the application provides a lightning strike effect after power transmission tower foundation bearing capacity reduction degree evaluation method, comprising:

[0053] S1, a plurality of lightning tests are carried out on the power transmission tower foundation by using different current intensities, and the wave velocity value change degree Δv of the power transmission tower foundation before and after lightning strike is measured by using an ultrasonic wave velocity meter i , and uniaxial compression tests are carried out on the power transmission tower foundation concrete before and after lightning strike to obtain the uniaxial compressive strength and the uniaxial compressive strength change degree Δσ i , and the functional relationship Δσ = f(Δv) between the wave velocity value change degree Δv i and the uniaxial compressive strength change degree Δσ i is established.

[0054] Before implementing the method, meteorological, seismic and geological data of the power transmission tower foundation erection area required for evaluation are obtained, mainly including lightning data information, site wind load information, soil layer physical parameters and site seismic wave information.

[0055] Specifically, a laboratory model test box consistent with the actual engineering conditions is designed according to the similarity ratio principle, a plurality of model test boxes are established according to the obtained lightning data information to set up a plurality of different intensity simulation current working conditions, and lightning tests are carried out on the power transmission tower foundation.

[0056] The wave velocity value change degree Δv i is:

[0057]

[0058] In the formula, v0 is the wave velocity value of the power transmission tower foundation before lightning strike; v i is the wave velocity value of the power transmission tower foundation after lightning strike, i = 1, 2, 3,..., n, and n represents the nth lightning test.

[0059] The uniaxial compressive strength change degree Δσ i is:

[0060]

[0061] In the formula, σ0 is the uniaxial compressive strength of the power transmission tower foundation before lightning strike; σ i is the uniaxial compressive strength of the power transmission tower foundation after lightning strike.

[0062] Specifically, the function relationship Δσ = f (Δv) can be Δσ = k1 (Δv). The wave velocity value change degree Δv i and the uniaxial compressive strength change degree Δσ i of the data obtained by the lightning test are input into the Origin software, and the function relationship Δσ = k1 (Δv) is obtained by using the built-in command of the software for function fitting.

[0063] S2, a plurality of power transmission tower foundation numerical models are established according to a plurality of lightning test results, the overlying load of each power transmission tower foundation numerical model is changed, and the overlying load corresponding to the stress value of the power transmission tower foundation numerical model reaching the respective uniaxial compressive strength is the allowable overlying load.

[0064] S3, the allowable overlying load is applied to the top of each power transmission tower foundation numerical model, the seismic wave is input at the bottom of the power transmission tower foundation numerical model, and the allowable overlying load is continuously reduced until the allowable overlying load corresponding to the inclination of the power transmission tower foundation numerical model reaching the threshold value under the action of the seismic wave is the first critical overlying load F i e , the power transmission tower foundation bearing capacity reduction degree ΔF i e under the action of the seismic wave is calculated according to the first critical overlying load, and the function relationship ΔF i e = g (Δσ) between the uniaxial compressive strength change degree Δσ i and the power transmission tower foundation bearing capacity reduction degree ΔF e is established. i w S4, the allowable overlying load is applied to the top of each power transmission tower foundation numerical model, the wind load is applied to the top of the power transmission tower foundation numerical model at the same time, and the allowable overlying load is continuously reduced until the allowable overlying load corresponding to the inclination of the power transmission tower foundation numerical model reaching the threshold value under the action of the wind load is the second critical overlying load F i w , the power transmission tower foundation bearing capacity reduction degree ΔF i w under the action of the wind load is calculated according to the second critical overlying load, and the function relationship ΔF i = h (Δσ) between the uniaxial compressive strength change degree Δσ w and the power transmission tower foundation bearing capacity reduction degree ΔF e is established.

[0065] In this embodiment, the threshold value of the inclination of the power transmission tower foundation is 0.5%.

[0066] Specifically, the function relationship ΔF e=k2(Δσ). The reduction in the bearing capacity of the transmission tower foundation under seismic wave action, ΔF, is calculated. i e and uniaxial compressive strength variation Δσ i The data is input into the Origin software, and the function relationship ΔF is obtained by using the software's built-in commands to perform function fitting. e = k2(Δσ).

[0067] Functional relationship ΔF w =h(Δσ) can be ΔF w =k3(Δσ). The reduction in the bearing capacity ΔF of the transmission tower foundation under wind load is calculated. i w and uniaxial compressive strength variation Δσ i The data is input into the Origin software, and the function relationship ΔF is obtained by using the software's built-in commands to perform function fitting. w =k3(Δσ).

[0068] S4. Based on the wave velocity change Δv i Variation of uniaxial compressive strength Δσ i The functional relationship between them is Δσ=f(Δv), and the reduction in the bearing capacity of the transmission tower foundation under seismic wave action is ΔF. i e Variation of uniaxial compressive strength Δσ i The functional relationship ΔF e =g(Δσ) establishes the wave velocity variation Δv i The reduction in bearing capacity ΔF of transmission tower foundation under seismic wave action i e The functional relationship ΔF e = g[f(Δv)]; based on the change in wave velocity Δv i Variation of uniaxial compressive strength Δσ i The functional relationship between them is Δσ=f(Δv), and the reduction in the bearing capacity of the transmission tower foundation under wind load is ΔF. i w Variation of uniaxial compressive strength Δσ i The functional relationship ΔF w =h(Δσ) establishes the wave velocity variation Δv i Reduction in bearing capacity ΔF of transmission tower foundation under wind load i w The functional relationship ΔF w =h[f(Δv)]; based on the wave velocity change Δv i The reduction in bearing capacity ΔF of transmission tower foundation under seismic wave action i e The functional relationship ΔF eg[f(Δv)], and the wave velocity value variation degree Δv i and the wind load acting on the power transmission tower foundation i w the function relationship ΔF w h[f(Δv)], to obtain the power transmission tower foundation bearing capacity reduction degree ΔF u {ΔF e , ΔF w} max .

[0069] Specifically, the function relationship ΔF e g[f(Δv)] can be ΔF e k2k1(Δv). The data of the power transmission tower foundation bearing capacity reduction degree ΔF i e and the wave velocity value variation degree Δv i are input into the Origin software, and the function relationship ΔF e k2k1(Δv) is obtained by using the built-in command of the software for function fitting.

[0070] The function relationship ΔF w h[f(Δv)] can be ΔF w k3k1(Δv). The data of the power transmission tower foundation bearing capacity reduction degree ΔF i w and the wave velocity value variation degree Δv i are input into the Origin software, and the function relationship ΔF w k3k1(Δv) is obtained by using the built-in command of the software for function fitting.

[0071] S5, using an ultrasonic wave velocity meter to measure and obtain the wave velocity value variation degree of the power transmission tower foundation after lightning action in an actual project, and determining the final bearing capacity reduction degree of the power transmission tower foundation after lightning action according to the power transmission tower foundation bearing capacity reduction degree considering the horizontal load effect after lightning action.

[0072] Specifically, in an actual project, the power transmission tower foundation bearing capacity reduction degree considering the horizontal load effect after lightning action is calculated according to the formula ΔF e g[f(Δv)], ΔF w h[f(Δv)], and ΔF u {ΔF e , ΔF w} max

[0073] ​The application firstly determines the relationship between the wave velocity value change degree and the uniaxial compressive strength change degree after lightning action by physical test method, then determines the allowable overburden load by numerical simulation method, and considering that the power transmission tower foundation will also be subjected to seismic load and wind load action in the process of continuing service after lightning action, the critical overburden load is determined by adjusting the allowable overburden load based on the inclination threshold index, the bearing capacity reduction degree of the power transmission tower foundation under the influence of seismic action and wind load is further determined, and the relationship between the bearing capacity reduction degree of the power transmission tower foundation and the uniaxial compressive strength change degree is established, the method fully considers the influence of horizontal load, the evaluation method is more scientific and comprehensive, and is more in line with the actual situation, so that the evaluation precision is greatly improved. Meanwhile, the application establishes the relationship between the wave velocity value change degree and the bearing capacity reduction degree of the power transmission tower foundation, the bearing capacity reduction degree of the power transmission tower foundation can be calculated by measuring the wave velocity value change degree of the power transmission tower foundation after lightning action, and the application has the advantages of simple operation, quickness and convenience, provides a quantitative method for the bearing capacity reduction degree evaluation of the power transmission tower foundation after lightning action, and has great application value for actual engineering.

[0074] Further, a plurality of power transmission tower foundation numerical models are established according to a plurality of lightning test results, including:

[0075] A unit numerical model is established in the discrete element software PFC to simulate the uniaxial compression test, and the mesoscopic parameters under each lightning test are determined by comparison and calibration with the uniaxial compression test curve and uniaxial compressive strength of the power transmission tower foundation after lightning action in the plurality of lightning tests.

[0076] A plurality of power transmission tower foundation numerical models are established, and the determined mesoscopic parameters under each lightning test are assigned to the particles and contacts of each power transmission tower foundation numerical model.

[0077] Further, the bearing capacity reduction degree ΔF of the power transmission tower foundation under the action of seismic wave is: i e F0 is the engineering design load of the power transmission tower foundation; F

[0078]

[0079] F0 is the engineering design load of the power transmission tower foundation; F i e The i-th first critical overburden load is:

[0080] The bearing capacity reduction degree ΔF of the power transmission tower foundation under the action of wind load is: i w F0 is the engineering design load of the power transmission tower foundation; F

[0081]

[0082] F0 is the engineering design load of the power transmission tower foundation; F i wThe i th first critical overburden load.

[0083] Further, the degree of reduction of the ultimate bearing capacity of the power transmission tower foundation after lightning stroke is determined, comprising:

[0084] The ratio of the total number of micro-cracks to the number of contacts of the numerical model of the power transmission tower foundation under different lightning tests when the critical overburden load is applied is recorded; the critical overburden load is {F i e , F i w} min , F i e The i th first critical overburden load, F i w The i th second critical overburden load;

[0085] When the increasing rate r s of the ratio is greater than the increasing rate r u of the uniaxial compressive strength, it is indicated that the deformation characteristic of the power transmission tower after lightning stroke is poorer than the strength characteristic, and the reduction degree adjustment coefficient β is calculated by the following formula:

[0086] β = 1 + (r s -r u );

[0087] The degree of reduction of the ultimate bearing capacity of the power transmission tower foundation after lightning stroke is obtained by multiplying the reduction degree of the bearing capacity of the power transmission tower foundation after lightning stroke considering the influence of horizontal load by the reduction degree adjustment coefficient.

[0088] Further, the increasing rate r s of the ratio is:

[0089]

[0090] In the formula, α n represents the ratio of the total number of micro-cracks to the number of contacts under the n th group of lightning tests; α 1 represents the ratio of the total number of micro-cracks to the number of contacts under the 1 st group of lightning tests; I n represents the current intensity under the n th group of lightning tests, and I 1 represents the current intensity under the 1 st group of lightning tests, which is increased from the 1 st group of lightning tests to the n th group of lightning tests;

[0091] The increasing rate r u of the uniaxial compressive strength is:

[0092]

[0093] In the formula, Δσ nrepresents the uniaxial compressive strength variation degree under the n-th group of lightning strike test; and Δσ1 represents the uniaxial compressive strength variation degree under the first group of lightning strike test.

[0094] The application considers the deformation performance of the power transmission tower foundation after lightning strike while evaluating the reduction degree of bearing capacity, and although the power transmission tower foundation can continue to bear after lightning strike, a large number of cracks have been generated in the interior of the power transmission tower foundation, that is, a large damage has been generated, and there is a certain risk in long-term service. Therefore, by comparing the ratio of the total number of microcracks to the contact number and the growth rate of the uniaxial compressive strength variation degree with the increase rate of the uniaxial compressive strength variation degree, the reduction degree adjustment coefficient of the bearing capacity of the power transmission tower foundation is introduced, the reduction degree of the bearing capacity is corrected to obtain the final reduction degree of the bearing capacity of the power transmission tower foundation, which is safe in engineering evaluation, thereby ensuring the reliability and practicability of the evaluation result.

[0095] Referring to Figure 2 A device for evaluating the reduction degree of the bearing capacity of a power transmission tower foundation after lightning strike, which is applied to the method for evaluating the reduction degree of the bearing capacity of a power transmission tower foundation after lightning strike, and comprises:

[0096] A first calculation module is configured to perform multiple groups of lightning strike tests on the power transmission tower foundation by using different current intensities, measure the wave velocity value variation degree of the power transmission tower foundation before and after lightning strike, perform uniaxial compression test on the concrete of the power transmission tower foundation before and after lightning strike to obtain the uniaxial compressive strength and the uniaxial compressive strength variation degree, and establish a functional relationship between the wave velocity value variation degree and the uniaxial compressive strength variation degree.

[0097] A second calculation module is configured to establish multiple numerical models of the power transmission tower foundation according to the results of the multiple groups of lightning strike tests, change the overlying load of each numerical model of the power transmission tower foundation until the stress value of the numerical model of the power transmission tower foundation reaches the corresponding load of the allowable overlying load when the uniaxial compressive strength is reached.

[0098] The third calculation module is configured to apply the allowable overburden load to the top of each power transmission tower foundation numerical model, input the seismic wave at the bottom of the power transmission tower foundation numerical model, and continuously reduce the allowable overburden load until the corresponding allowable overburden load when the inclination of the power transmission tower foundation numerical model under the action of the seismic wave reaches a threshold value is a first critical overburden load, calculate the bearing capacity reduction degree of the power transmission tower foundation under the action of the seismic wave according to the first critical overburden load, and establish a functional relationship between the bearing capacity reduction degree of the power transmission tower foundation under the action of the seismic wave and the uniaxial compressive strength variation degree; the allowable overburden load is applied to the top of each power transmission tower foundation numerical model, and at the same time, the wind load is applied to the top of the power transmission tower foundation numerical model, and the allowable overburden load is continuously reduced until the corresponding allowable overburden load when the inclination of the power transmission tower foundation numerical model under the action of the wind load reaches a threshold value is a second critical overburden load, the bearing capacity reduction degree of the power transmission tower foundation under the action of the wind load is calculated according to the second critical overburden load, and a functional relationship between the bearing capacity reduction degree of the power transmission tower foundation under the action of the wind load and the uniaxial compressive strength variation degree is established;

[0099] The fourth calculation module is configured to establish a functional relationship between the wave velocity value variation degree and the bearing capacity reduction degree of the power transmission tower foundation under the action of the seismic wave according to the functional relationship between the wave velocity value variation degree and the uniaxial compressive strength variation degree and the functional relationship between the bearing capacity reduction degree of the power transmission tower foundation under the action of the seismic wave and the uniaxial compressive strength variation degree; a functional relationship between the wave velocity value variation degree and the bearing capacity reduction degree of the power transmission tower foundation under the action of the wind load is established according to the functional relationship between the wave velocity value variation degree and the uniaxial compressive strength variation degree and the functional relationship between the bearing capacity reduction degree of the power transmission tower foundation under the action of the wind load and the uniaxial compressive strength variation degree; and the bearing capacity reduction degree of the power transmission tower foundation under the action of lightning considering the influence of horizontal load is obtained according to the functional relationship between the wave velocity value variation degree and the bearing capacity reduction degree of the power transmission tower foundation under the action of the seismic wave and the functional relationship between the wave velocity value variation degree and the bearing capacity reduction degree of the power transmission tower foundation under the action of the wind load.

[0100] The bearing capacity reduction degree determination module is configured to obtain the wave velocity value variation degree of the power transmission tower foundation after the action of lightning in an actual engineering, and determine the final bearing capacity reduction degree of the power transmission tower foundation after the action of lightning according to the bearing capacity reduction degree of the power transmission tower foundation under the action of lightning considering the influence of horizontal load.

[0101] Referring to Figure 3 The application also provides a lightning action power transmission tower foundation bearing capacity reduction degree evaluation device, which comprises a memory and a processor.

[0102] The memory is configured to store computer program codes and transmit the computer program codes to the processor.

[0103] The processor is configured to execute the above-mentioned lightning stroke tower foundation bearing capacity reduction degree evaluation method according to the instructions in the computer program code.

[0104] The application further provides a computer readable storage medium, wherein the computer readable storage medium stores a computer program, and the computer program is executed by a processor to implement the above-mentioned lightning stroke tower foundation bearing capacity reduction degree evaluation method.

[0105] Generally, the computer instructions used to implement the method of the application can be carried by any combination of one or more computer readable storage media. The non-transitory computer readable storage medium can include any computer readable medium except a signal transiting in a transitory manner.

[0106] The computer readable storage medium can be, for example but not limited to, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, device or apparatus, or any combination of the above. More specific examples (non-exhaustive list) of the computer readable storage medium include an electrical connection having one or more wires, a portable computer diskette, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the above. In this application, the computer readable storage medium can be any tangible medium that contains or stores a program that can be used by or in connection with an instruction execution system, apparatus or device.

[0107] The computer program code used to implement the application can be written in one or more programming languages or combinations of languages including object oriented programming languages such as Java, Smalltalk, C++ or conventional procedural programming languages such as the "C" programming language or similar programming languages. In particular, Python language suitable for neural network computing and platform frameworks based on TensorFlow, PyTorch, etc. can be used. The program code can execute entirely on the user's computer, partly on the user's computer, as a stand-alone software package, partly on the user's computer and partly on a remote computer or entirely on the remote computer or server. In the latter scenario, the remote computer can be connected to the user's computer through any type of network, including a local area network (LAN) or a wide area network (WAN), or the connection can be made to an external computer (for example, through the Internet using an Internet Service Provider).

[0108] The above device and non-transitory computer readable storage medium can refer to the specific description of the method and beneficial effects of evaluating the reduction degree of the foundation bearing capacity of the power transmission tower after lightning stroke, which will not be described here.

[0109] Although the embodiments of the present application have been shown and described above, it should be understood by those skilled in the art that the above embodiments are exemplary and cannot be interpreted as limiting the present application, and those skilled in the art can make changes, modifications, replacements and variations to the above embodiments within the scope of the present application.

Claims

1. A method for evaluating the degree of reduction in the bearing capacity of a power transmission tower foundation after a lightning stroke, characterized by, The method comprises the following steps: a plurality of lightning strike tests are carried out on the power transmission tower foundation by using different current intensities, the wave velocity value change degree of the power transmission tower foundation before and after lightning strike is measured, uniaxial compression tests are carried out on the power transmission tower foundation concrete before and after lightning strike to obtain the uniaxial compressive strength and the uniaxial compressive strength change degree, and a functional relationship between the wave velocity value change degree and the uniaxial compressive strength change degree is established; a plurality of power transmission tower foundation numerical models are established according to the results of the plurality of lightning strike tests, the overlying load of each power transmission tower foundation numerical model is changed, and the overlying load corresponding to the stress value of the power transmission tower foundation numerical model reaching the respective uniaxial compressive strength is the allowable overlying load; the allowable overlying load is applied to the top of each power transmission tower foundation numerical model, the seismic wave is input at the bottom of the power transmission tower foundation numerical model, and the allowable overlying load is continuously reduced until the allowable overlying load corresponding to the inclination of the power transmission tower foundation numerical model reaching a threshold value under the action of the seismic wave is the first critical overlying load, the bearing capacity reduction degree of the power transmission tower foundation under the action of the seismic wave is calculated according to the first critical overlying load, and a functional relationship between the bearing capacity reduction degree of the power transmission tower foundation under the action of the seismic wave and the uniaxial compressive strength change degree is established; the allowable overlying load is applied to the top of each power transmission tower foundation numerical model, the wind load is applied to the top of the power transmission tower foundation numerical model at the same time, and the allowable overlying load is continuously reduced until the allowable overlying load corresponding to the inclination of the power transmission tower foundation numerical model reaching a threshold value under the action of the wind load is the second critical overlying load, the bearing capacity reduction degree of the power transmission tower foundation under the action of the wind load is calculated according to the second critical overlying load, and a functional relationship between the bearing capacity reduction degree of the power transmission tower foundation under the action of the wind load and the uniaxial compressive strength change degree is established; a functional relationship between the wave velocity value change degree and the bearing capacity reduction degree of the power transmission tower foundation under the action of the seismic wave is established according to the functional relationship between the wave velocity value change degree and the uniaxial compressive strength change degree and the functional relationship between the bearing capacity reduction degree of the power transmission tower foundation under the action of the seismic wave and the uniaxial compressive strength change degree; a functional relationship between the wave velocity value change degree and the bearing capacity reduction degree of the power transmission tower foundation under the action of the wind load is established according to the functional relationship between the wave velocity value change degree and the uniaxial compressive strength change degree and the functional relationship between the bearing capacity reduction degree of the power transmission tower foundation under the action of the wind load and the uniaxial compressive strength change degree; and the bearing capacity reduction degree of the power transmission tower foundation after lightning strike considering the influence of horizontal load is obtained according to the functional relationship between the wave velocity value change degree and the bearing capacity reduction degree of the power transmission tower foundation under the action of the seismic wave and the functional relationship between the wave velocity value change degree and the bearing capacity reduction degree of the power transmission tower foundation under the action of the wind load; the wave velocity value change degree of the power transmission tower foundation after lightning strike in an actual project is obtained, and the final bearing capacity reduction degree of the power transmission tower foundation after lightning strike is determined according to the bearing capacity reduction degree of the power transmission tower foundation after lightning strike considering the influence of horizontal load.

2. The method according to claim 1, wherein The method comprises the following steps: The uniaxial compression test is simulated by establishing a unit numerical model in the discrete element software PFC, and the mesoscopic parameters under each lightning test are determined by comparing and calibrating the uniaxial compression test curves and the uniaxial compressive strength of the lightning-affected power transmission tower foundation concrete in multiple groups of lightning tests; Multiple power transmission tower foundation numerical models are established, and the determined mesoscopic parameters under each lightning test are assigned to the particles and contacts of each power transmission tower foundation numerical model.

3. The method according to claim 1, wherein the threshold of the inclination of the power transmission tower foundation is 0.5%. The degree of reduction of the bearing capacity of the power transmission tower foundation under the action of the seismic wave is ΔF i e F is: In the formula, F0 is the engineering design load of the power transmission tower foundation; F i e is the i-th first critical overburden load; The wind load acting on the power transmission tower foundation bearing capacity reduction degree ΔF i w F = In the formula, F i w is the ith second critical overburden load.

4. The method for evaluating the reduction degree of the bearing capacity of a power transmission tower foundation after lightning stroke according to claim 1, characterized in that, The bearing capacity reduction degree ΔF of the power transmission tower foundation considering the horizontal load effect after the lightning stroke u is: ΔF u = {ΔF e , ΔF w} max ; In the formula, ΔF e is a function value of the reduction degree of the bearing capacity of the power transmission tower foundation and the uniaxial compressive strength variation degree under the action of seismic waves; ΔF w is a function value of the reduction degree of the bearing capacity of the power transmission tower foundation and the uniaxial compressive strength variation degree under the action of wind load.

5. The method for evaluating the reduction degree of the bearing capacity of a power transmission tower foundation after lightning stroke according to claim 1, characterized in that, The method further comprises:

6. The method for evaluating the reduction degree of the bearing capacity of a power transmission tower foundation after lightning stroke according to claim 1, characterized in that, The final bearing capacity reduction degree of the lightning-affected power transmission tower foundation is determined by multiplying the bearing capacity reduction degree of the lightning-affected power transmission tower foundation under the horizontal load by the reduction degree adjustment coefficient. Record the ratio of the total number of micro-cracks to the total number of contacts of the numerical model of the power transmission tower foundation under different lightning tests when the critical overburden load is applied; the critical overburden load is {F i e , F i w} min , wherein F i e is the i th first critical overburden load, F i w is the i th second critical overburden load; When the rate of increase r s of the ratio is greater than the rate of increase r u of the uniaxial compressive strength variation, the reduction degree adjustment coefficient β is calculated using the following equation: β＝1+(r s -r u )； 7. The method according to claim 6, wherein the method further comprises: The device is applied to the method according to any one of claims 1-7, and the device comprises: The rate of increase r of said ratio s is: In the formula, α n represents the ratio of the total number of microcracks to the number of contacts under the n-th group of lightning tests; α1represents the ratio of the total number of microcracks to the number of contacts under the first group of lightning tests; I n represents the current intensity under the n-th group of lightning tests, and I1represents the current intensity under the first group of lightning tests, the current intensity being increased from the first group of lightning tests to the n-th group of lightning tests. The rate of increase r of the uniaxial compressive strength variation degree u is: where Δσ n represents the uniaxial compressive strength variation degree under the nth group of lightning tests; Δσ1represents the uniaxial compressive strength variation degree under the first group of lightning tests.

8. A lightning stroke effect post-tower foundation bearing capacity reduction degree evaluation device characterized by, The first calculation module is configured to perform multiple groups of lightning tests on the power transmission tower foundation by using different current intensities, measure the wave velocity value change degree of the power transmission tower foundation before and after lightning, perform uniaxial compression tests on the concrete of the power transmission tower foundation before and after lightning to obtain the uniaxial compressive strength and the uniaxial compressive strength change degree, and establish a functional relationship between the wave velocity value change degree and the uniaxial compressive strength change degree; The second calculation module is configured to establish multiple power transmission tower foundation numerical models according to the results of the multiple groups of lightning tests, change the overlying load of each power transmission tower foundation numerical model, and stop until the stress value of the power transmission tower foundation numerical model reaches the overlying load corresponding to the uniaxial compressive strength, which is the allowable overlying load; The third calculation module is configured to apply the allowable overlying load to the top of each power transmission tower foundation numerical model, input the seismic wave at the bottom of the power transmission tower foundation numerical model, and continuously reduce the allowable overlying load until the allowable overlying load corresponding to the inclination threshold of the power transmission tower foundation numerical model under the action of the seismic wave is the first critical overlying load, calculate the bearing capacity reduction degree of the power transmission tower foundation under the action of the seismic wave according to the first critical overlying load, and establish a functional relationship between the bearing capacity reduction degree of the power transmission tower foundation under the action of the seismic wave and the uniaxial compressive strength change degree; the third calculation module is further configured to apply the allowable overlying load to the top of each power transmission tower foundation numerical model, apply the wind load to the top of the power transmission tower foundation numerical model at the same time, and continuously reduce the allowable overlying load until the allowable overlying load corresponding to the inclination threshold of the power transmission tower foundation numerical model under the action of the wind load is the second critical overlying load, calculate the bearing capacity reduction degree of the power transmission tower foundation under the action of the wind load according to the second critical overlying load, and establish a functional relationship between the bearing capacity reduction degree of the power transmission tower foundation under the action of the wind load and the uniaxial compressive strength change degree. ​ The fourth calculation module is configured to establish a function relationship between the wave velocity value change degree and the foundation bearing capacity reduction degree under the action of the seismic wave according to a function relationship between the wave velocity value change degree and the uniaxial compressive strength change degree and a function relationship between the foundation bearing capacity reduction degree and the uniaxial compressive strength change degree under the action of the seismic wave; establish a function relationship between the wave velocity value change degree and the foundation bearing capacity reduction degree under the action of the wind load according to a function relationship between the wave velocity value change degree and the uniaxial compressive strength change degree and a function relationship between the foundation bearing capacity reduction degree and the uniaxial compressive strength change degree under the action of the wind load; and obtain the foundation bearing capacity reduction degree of the transmission tower under the action of the lightning strike considering the influence of the horizontal load according to the function relationship between the wave velocity value change degree and the foundation bearing capacity reduction degree under the action of the seismic wave and the function relationship between the wave velocity value change degree and the foundation bearing capacity reduction degree under the action of the wind load. The bearing capacity reduction degree determination module is configured to obtain the wave velocity value change degree of the transmission tower foundation after the action of the lightning strike in an actual project, and determine the final foundation bearing capacity reduction degree of the transmission tower after the action of the lightning strike according to the foundation bearing capacity reduction degree of the transmission tower under the action of the lightning strike considering the influence of the horizontal load. 9.A device for evaluating the foundation bearing capacity reduction degree of a transmission tower after the action of a lightning strike, comprising: a memory and a processor; the memory is configured to store computer program codes and transmit the computer program codes to the processor; the processor is configured to execute the method according to any one of claims 1 to 7 according to the instructions in the computer program codes.

10. A computer-readable storage medium, characterized in that, The computer program is stored on the computer readable storage medium, and the computer program is executed by the processor to implement the method according to any one of claims 1 to 7.

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