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

Abstract

The invention discloses a method and device for evaluating the bearing capacity reduction degree of a power transmission tower foundation after lightning stroke action. The method comprises the steps of establishing a function relationship between the wave velocity value change degree and the uniaxial compressive strength change degree of the power transmission tower foundation before and after lightning stroke action; determining an allowable overburden load of the transmission tower foundation numerical model, and respectively establishing a function relationship between the bearing capacity reduction degree and the uniaxial compressive strength change degree of the transmission tower foundation under the action of seismic waves and wind loads according to the allowable overburden load; respectively establishing a function relationship between the wave velocity value change degree and the transmission tower foundation bearing capacity reduction degree under the action of seismic waves and wind loads, and obtaining the transmission tower foundation bearing capacity reduction degree considering the horizontal load influence after the lightning stroke action; and the final bearing capacity reduction degree of the transmission tower foundation is determined according to the wave velocity value change degree of the transmission tower foundation after the actual engineering lightning stroke effect. The method fully considers the influence of the horizontal load effect, and improves the evaluation precision of the reduction degree of the bearing capacity of the transmission tower foundation after the lightning stroke effect.

Description

Technical Field

[0001] The present invention relates to the technical field of power transmission tower foundations, and in particular to a method and device for evaluating the degree of reduction in the bearing capacity of a power transmission tower foundation after a lightning strike. Background Art

[0002] As the demand for electricity continues to rise, the scale and complexity of power transmission project construction are also gradually expanding, especially in the field of long-distance power transmission and high-voltage power transmission. As an important part of the power transmission project, the foundation of the power transmission tower plays an important role in maintaining the stability of the power transmission project. However, the foundation of the power transmission tower, which is exposed to the external environment for a long time, is often threatened by various natural disasters such as lightning strikes, storms, and earthquakes. Among them, lightning strikes are one of the main reasons for the instability of the power transmission tower foundation. Lightning strikes will not only cause certain damage to it, but also reduce the bearing capacity of the power transmission tower foundation.

[0003] Although the transmission tower foundation can continue to serve after a lightning strike, the reduction in bearing capacity will pose a safety hazard to 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 are still major deficiencies in the assessment of the bearing capacity of the tower foundation after a lightning strike. The existing assessment methods are mostly empirical judgments, lacking scientific quantitative analysis tools, and it is difficult to comprehensively and accurately assess the degree of reduction in the bearing capacity of the transmission tower foundation after a lightning strike. Therefore, the research on the assessment method of the bearing capacity of the transmission tower foundation after a lightning strike has important practical significance. Summary of the invention

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

[0005] To achieve the above objectives, the technical solution of the present invention is:

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

[0007] Conduct multiple groups of lightning tests on the transmission tower foundation using different current intensities, and measure the change in the wave velocity value of the transmission tower foundation before and after the lightning strike. Conduct uniaxial compression tests on the transmission tower foundation concrete before and after the lightning strike to obtain the uniaxial compressive strength and the change in uniaxial compressive strength, and establish a functional relationship between the change in wave velocity value and the change in uniaxial compressive strength.

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

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

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

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

[0012] The method of establishing multiple transmission tower foundation numerical models according to multiple groups of lightning strike test results includes:

[0013] A unit numerical model was established in the discrete element software PFC to simulate the uniaxial compression test. The mesoscopic parameters under each group of lightning strike tests were determined by comparing and calibrating the uniaxial compression test curves and uniaxial compressive strength of the transmission tower foundation concrete after lightning strikes in multiple groups of lightning strike tests.

[0014] A variety of transmission tower foundation numerical models are established, and the mesoscopic parameters determined under each set of lightning strike tests are assigned to the particles and contacts of each transmission tower foundation numerical model established.

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

[0016]

[0017] Where F0 is the engineering design load of the transmission tower foundation; F i e is the i-th first critical overburden load;

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

[0019]

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

[0021] The reduction degree of the transmission tower foundation bearing capacity ΔF after the lightning strike considering the influence of horizontal load u for:

[0022] ΔF u ={ΔF e , ΔF w} max ;

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

[0024] The threshold for transmission tower foundation inclination is 0.5%.

[0025] Determining the degree of reduction in the ultimate bearing capacity of the transmission tower foundation after a lightning strike includes:

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

[0027] When the rate of increase of the ratio is r s Greater than the rate of increase of the uniaxial compressive strength change r u When , the reduction adjustment coefficient β is calculated using the following formula:

[0028] β=1+(r s -r u );

[0029] The reduction degree of the transmission tower foundation bearing capacity after lightning strike considering the influence of horizontal load is multiplied by the reduction degree adjustment coefficient to obtain the final reduction degree of the transmission tower foundation bearing capacity after lightning strike.

[0030] The rate of increase of the ratio r s for:

[0031]

[0032] In the formula, α n represents the ratio of the total number of microcracks to the number of contacts under the nth group of lightning tests; α1 represents the ratio of the total number of microcracks to the number of contacts under the first group of lightning tests; I n I represents the current intensity under the nth group of lightning tests, I1 represents the current intensity under the first group of lightning tests, and the current intensity increases from the first group of lightning tests to the nth group of lightning tests;

[0033] The rate of increase of the uniaxial compressive strength change is r u for:

[0034]

[0035] In the formula, Δσ n It represents the variation of uniaxial compressive strength under the nth group of lightning strike tests; Δσ1 represents the variation of uniaxial compressive strength under the first group of lightning strike tests.

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

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

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

[0039] The third calculation module is used to apply the allowable overburden load to the top of each transmission tower foundation numerical model, input the seismic wave at the bottom of the transmission tower foundation numerical model, and continuously reduce the allowable overburden load until the inclination of the transmission tower foundation numerical model under the action of the seismic wave reaches a threshold value. The allowable overburden load corresponding to the threshold value is the first critical overburden load, and the reduction degree of the transmission tower foundation bearing capacity under the action of the seismic wave is calculated according to the first critical overburden load, and the function of the reduction degree of the transmission tower foundation bearing capacity under the action of the seismic wave and the change degree of the uniaxial compressive strength is established. numerical relationship; applying the allowable overburden load to the top of each transmission tower foundation numerical model, and applying the wind load to the top of the transmission tower foundation numerical model at the same time, and continuously reducing the allowable overburden load until the inclination of the transmission tower foundation numerical model under the wind load reaches the threshold value, and the allowable overburden load corresponding to the threshold value is the second critical overburden load, and the reduction degree of the transmission tower foundation bearing capacity under the wind load is calculated according to the second critical overburden load, and the functional relationship between the reduction degree of the transmission tower foundation bearing capacity under the wind load and the change degree of the uniaxial compressive strength is established;

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

[0041] The module for determining the degree of reduction in bearing capacity is used to obtain the degree of change in the wave velocity value of the transmission tower foundation after a lightning strike in an actual project, and to determine the degree of reduction in the final bearing capacity of the transmission tower foundation after a lightning strike based on the degree of reduction in the bearing capacity of the transmission tower foundation considering the influence of horizontal loads after a lightning strike.

[0042] A device for evaluating the reduction degree of bearing capacity of a transmission tower foundation after a lightning strike, comprising a memory and a processor;

[0043] The memory is used to store computer program code and transmit the computer program code to the processor;

[0044] The processor is used to execute the method according to the instructions in the computer program code.

[0045] A computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the method described above is implemented.

[0046] Compared with the prior art, the present invention has the following beneficial effects:

[0047] In a method and device for evaluating the degree of reduction in the bearing capacity of a transmission tower foundation after a lightning strike of the present invention, the method first determines the relationship between the change in wave velocity value before and after the lightning strike and the change in uniaxial compressive strength, and then uses a numerical simulation method to determine the allowable overlying load. Considering that the transmission tower foundation will be subjected to earthquake load and wind load in the process of continuing service after the lightning strike, based on the inclination threshold index, the critical overlying load is determined by adjusting the allowable overlying load, and the reduction in the bearing capacity of the transmission tower foundation under the influence of earthquake and wind load is further determined, and the relationship between the reduction in the bearing capacity of the transmission tower foundation and the change in uniaxial compressive strength is established. The method fully considers the influence of horizontal load, and the evaluation method is more scientific and comprehensive, more in line with the actual situation, and greatly improves the evaluation accuracy. At the same time, the relationship between the change of wave velocity value and the reduction of the bearing capacity of the transmission tower foundation is established. By measuring the change of the wave velocity value of the transmission tower foundation after the lightning strike, the reduction of the bearing capacity of the transmission tower foundation is calculated. This method has the advantages of simple operation, fast and convenient, and provides a quantitative method for evaluating the reduction of the bearing capacity of the transmission tower foundation after the lightning strike, which has great application value to actual projects. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 The present invention is a flow chart of a method for evaluating the reduction degree of the bearing capacity of a transmission tower foundation after a lightning strike.

[0049] Figure 2 The present invention is a structural block diagram of a device for evaluating the degree of reduction in the bearing capacity of a transmission tower foundation after a lightning strike.

[0050] Figure 3 The present invention is a structural block diagram of a device for evaluating the degree of reduction in the bearing capacity of a transmission tower foundation after a lightning strike. DETAILED DESCRIPTION

[0051] The present invention is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0052] See also Figure 1 The present invention provides a method for evaluating the reduction degree of the bearing capacity of a transmission tower foundation after a lightning strike, comprising:

[0053] S1. Conduct multiple lightning tests on the transmission tower foundation using different current intensities, and use an ultrasonic wave velocity meter to measure the change in the wave velocity value Δv of the transmission tower foundation before and after the lightning strike. i , and the uniaxial compression test of the transmission tower foundation concrete before and after the lightning strike was performed to obtain the uniaxial compressive strength and the uniaxial compressive strength change Δσ i , and establish the wave velocity value change Δv i Variation of uniaxial compressive strength Δσ i The functional relationship between them is Δσ=f(Δv).

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

[0055] Specifically, a laboratory model test box that is consistent with actual engineering conditions is designed based on the similarity ratio principle. A variety of simulated current conditions of different intensities are set up according to the acquired lightning data information and multiple model test boxes are established to carry out lightning strike tests on the foundations of transmission towers.

[0056] Wave velocity change Δv i for:

[0057]

[0058] Where v0 is the wave velocity value of the transmission tower foundation before the lightning strike; v i is the wave velocity value of the transmission tower foundation after lightning strike, i=1, 2, 3, ..., n, where n represents the nth group of lightning strike tests.

[0059] Uniaxial compressive strength variation Δσ i for:

[0060]

[0061] Where σ0 is the uniaxial compressive strength of the transmission tower foundation before lightning strike; σ i It is the uniaxial compressive strength of the transmission tower foundation after lightning strike.

[0062] Specifically, the functional relationship Δσ=f(Δv) can be Δσ=k1(Δv). The wave velocity value change Δv obtained by the lightning test i and the uniaxial compressive strength variation Δσ i The data was input into the Origin software, and the function was fitted using the built-in commands of the software to obtain the functional relationship Δσ=k1(Δv).

[0063] S2. Establish multiple transmission tower foundation numerical models based on multiple groups of lightning test results, and change the overlying load of each transmission tower foundation numerical model until the load corresponding to the stress value of the transmission tower foundation numerical model reaches the respective uniaxial compressive strength as the allowable overlying load.

[0064] S3, applying the allowable overburden load to the top of each transmission tower foundation numerical model, inputting the seismic wave at the bottom of the transmission tower foundation numerical model, and continuously reducing the allowable overburden load until the inclination of the transmission tower foundation numerical model under the action of the seismic wave reaches the threshold value, and the corresponding allowable overburden load is the first critical overburden load F i e , according to the first critical overburden load, the reduction degree of the transmission tower foundation bearing capacity under the action of earthquake waves is calculated as ΔF i e , and establish the reduction degree of transmission tower foundation bearing capacity ΔF under the action of earthquake waves i e Variation of uniaxial compressive strength Δσ i Functional relationship ΔF e = g(Δσ); the allowable overburden load is applied to the top of each transmission tower foundation numerical model, and the wind load is applied to the top of the transmission tower foundation numerical model, and the allowable overburden load is continuously reduced until the inclination of the transmission tower foundation numerical model under the wind load reaches the threshold. The corresponding allowable overburden load is the second critical overburden load F i w , according to the second critical overburden load, the reduction degree of the transmission tower foundation bearing capacity under wind load is calculated as ΔF i w , and establish the reduction degree of transmission tower foundation bearing capacity under wind load ΔF i w Variation of uniaxial compressive strength Δσ i Functional relationship ΔF w =h(Δσ).

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

[0066] Specifically, the functional relationship ΔF e =g(Δσ) can be ΔF e= k2(Δσ). The transmission tower foundation bearing capacity reduction degree ΔF obtained under the action of earthquake waves i e and the uniaxial compressive strength variation Δσ i The data was input into Origin software, and the function relationship ΔF was obtained by using the built-in command of the software for function fitting. e =k2(Δσ).

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

[0068] S4, according to the change of wave velocity value △v i Variation of uniaxial compressive strength Δσ i The functional relationship between Δσ=f(Δv) and the reduction degree of the bearing capacity of the transmission tower foundation under the action of earthquake waves ΔF i e Variation of uniaxial compressive strength Δσ i Functional relationship ΔF e =g(Δσ) to establish the wave velocity value change Δv i The reduction degree of transmission tower foundation bearing capacity under earthquake wave ΔF i e Functional relationship ΔF e =g|f(Δv)]; according to the change of wave velocity value Δv i Variation of uniaxial compressive strength △σ i The functional relationship between Δσ=f(Δv) and the reduction degree of the bearing capacity of the transmission tower foundation under wind load ΔF i w Variation of uniaxial compressive strength △σ i Functional relationship ΔF w =h(Δσ) to establish the wave velocity value change Δv i The reduction degree of transmission tower foundation bearing capacity under wind load ΔF i w Functional relationship ΔF w =h|f(△v)]; according to the change of wave velocity value Δv i The reduction degree of transmission tower foundation bearing capacity under earthquake wave ΔF i e Functional relationship ΔF e=g[f(Δv)], and the wave velocity change Δv i The reduction degree of transmission tower foundation bearing capacity under wind load ΔF i w Functional relationship ΔF w = h[f(△v)], and the reduction degree of the transmission tower foundation bearing capacity after lightning strike considering the influence of horizontal load is obtained. u ={△F e , △F w} max .

[0069] Specifically, the functional relationship ΔF e =g|f(△v)] can be ΔF e = k2k1(△v). The transmission tower foundation bearing capacity reduction degree ΔF obtained under the action of earthquake waves i e and the wave velocity variation △v i The data was input into Origin software, and the function relationship ΔF was obtained by using the built-in command of the software for function fitting. e =k2k1(△v).

[0070] Functional relationship ΔF w =h[f(△v)|can be ΔF w = k3k1(△v). The transmission tower foundation bearing capacity under wind load is reduced by ΔF i w and the wave velocity change Δv i The data was input into Origin software, and the function relationship ΔF was obtained by using the built-in command of the software for function fitting. w =k3k1(△v).

[0071] S5. Use an ultrasonic velocimeter to measure and obtain the change in the wave velocity value of the transmission tower foundation after lightning strike in actual projects, and determine the degree of reduction in the final bearing capacity of the transmission tower foundation after lightning strike based on the reduction in the bearing capacity of the transmission tower foundation considering the influence of horizontal load after lightning strike.

[0072] Specifically, in actual engineering, according to the formula ΔF e =g[f(△v)], ΔF w =h[f(Δv)] and ΔF u ={ΔF e , ΔF w} max Calculate the reduction in the bearing capacity of the transmission tower foundation after lightning strike considering the influence of horizontal load.

[0073] The present invention first uses a physical test method to determine the relationship between the change in wave velocity value and the change in uniaxial compressive strength after a lightning strike, and then uses a numerical simulation method to determine the allowable overburden load. Considering that the transmission tower foundation will also be subjected to earthquake load and wind load in the process of continuing to serve after a lightning strike, the critical overburden load is determined by adjusting the allowable overburden load based on the inclination threshold index, and the reduction in the bearing capacity of the transmission tower foundation under the influence of earthquake and wind load is further determined, and the relationship between the reduction in the bearing capacity of the transmission tower foundation and the change in uniaxial compressive strength is established. The method fully considers the influence of horizontal loads, and the evaluation method is more scientific and comprehensive, more in line with actual conditions, and greatly improves the evaluation accuracy. At the same time, the present invention establishes the relationship between the change in wave velocity value and the reduction in the bearing capacity of the transmission tower foundation, and can infer the reduction in the bearing capacity of the transmission tower foundation by measuring the change in wave velocity value of the transmission tower foundation after a lightning strike. It has the advantages of simple operation, quickness and convenience, and provides a quantitative method for evaluating the reduction in the bearing capacity of the transmission tower foundation after a lightning strike, which has great application value for actual projects.

[0074] Furthermore, multiple transmission tower foundation numerical models were established based on multiple groups of lightning test results, including:

[0075] A unit numerical model was established in the discrete element software PFC to simulate the uniaxial compression test. The mesoscopic parameters under each group of lightning strike tests were determined by comparing and calibrating the uniaxial compression test curves and uniaxial compressive strength of the transmission tower foundation concrete after lightning strikes in multiple groups of lightning strike tests.

[0076] A variety of transmission tower foundation numerical models are established, and the mesoscopic parameters determined under each set of lightning strike tests are assigned to the particles and contacts of each transmission tower foundation numerical model established.

[0077] Furthermore, the reduction degree of the bearing capacity of the transmission tower foundation under the action of earthquake waves is ΔF i e for:

[0078]

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

[0080] Reduction degree of transmission tower foundation bearing capacity under wind load ΔF i w for:

[0081]

[0082] In the formula, F i wis the i-th second critical overburden load.

[0083] Furthermore, the degree of reduction in the ultimate bearing capacity of the transmission tower foundation after the lightning strike is determined, including:

[0084] Record the ratio of the total number of microcracks to the number of contacts in the numerical model of the transmission tower foundation when the critical overburden load is applied under different lightning tests; the critical overburden load is {F i e , F i w} min , where F i e is the ith first critical overburden load, F i w is the i-th second critical overburden load;

[0085] When the rate of increase of the ratio, s, is greater than the rate of increase of the change of the uniaxial compressive strength, u, it means that the deformation characteristics of the transmission tower after lightning strike are poor compared with the strength characteristics. The reduction adjustment coefficient β is calculated by the following formula:

[0086] β=1+(r s -r u );

[0087] The reduction degree of the transmission tower foundation bearing capacity after lightning strike considering the influence of horizontal load is multiplied by the reduction degree adjustment coefficient to obtain the final reduction degree of the transmission tower foundation bearing capacity after lightning strike.

[0088] Furthermore, the rate of increase of the ratio r S for:

[0089]

[0090] In the formula, α n represents the ratio of the total number of microcracks to the number of contacts under the nth group of lightning tests; α1 represents the ratio of the total number of microcracks to the number of contacts under the first group of lightning tests; I n I represents the current intensity under the nth group of lightning tests, I1 represents the current intensity under the first group of lightning tests, and the current intensity increases from the first group of lightning tests to the nth group of lightning tests;

[0091] The rate of increase of the change in uniaxial compressive strength r u for:

[0092]

[0093] In the formula, Δσ n It represents the variation of uniaxial compressive strength under the nth group of lightning strike tests; Δσ1 represents the variation of uniaxial compressive strength under the first group of lightning strike tests.

[0094] The present invention considers the deformation performance of the transmission tower foundation after the lightning strike while evaluating the degree of bearing capacity reduction. Although the transmission tower foundation can continue to bear the load after the lightning strike, many cracks have been generated inside it, that is, it has been severely damaged, and there is a certain risk in long-term service. Therefore, by comparing the ratio of the total number of microcracks to the number of contacts and its growth rate with the increase rate of the uniaxial compressive strength change, an adjustment coefficient for the degree of bearing capacity reduction of the transmission tower foundation is introduced, and the degree of bearing capacity reduction is corrected to obtain the final degree of bearing capacity reduction of the transmission tower foundation. This is safer in engineering evaluation, thereby ensuring the credibility and practicality of the evaluation results.

[0095] See also Figure 2 A device for evaluating the degree of reduction in the bearing capacity of a transmission tower foundation after a lightning strike, which is applied to the above-mentioned method for evaluating the degree of reduction in the bearing capacity of a transmission tower foundation after a lightning strike, and the device comprises:

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

[0097] The second calculation module is used to establish multiple transmission tower foundation numerical models according to multiple groups of lightning test results, and change the overlying load of each transmission tower foundation numerical model until the load corresponding to the stress value of the transmission tower foundation numerical model reaches the respective uniaxial compressive strength as the allowable overlying load;

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

[0099] The fourth calculation module is used to establish a functional relationship between the wave velocity change and the reduction of the bearing capacity of the transmission tower foundation under the action of earthquake waves according to the functional relationship between the wave velocity change and the uniaxial compressive strength change and the functional relationship between the reduction of the bearing capacity of the transmission tower foundation under the action of earthquake waves and the uniaxial compressive strength change; establish a functional relationship between the wave velocity change and the reduction of the bearing capacity of the transmission tower foundation under wind load according to the functional relationship between the wave velocity change and the uniaxial compressive strength change and the uniaxial compressive strength change; obtain the reduction of the bearing capacity of the transmission tower foundation after lightning strike considering the influence of horizontal load according to the functional relationship between the wave velocity change and the reduction of the bearing capacity of the transmission tower foundation under earthquake waves and the wave velocity change and the reduction of the bearing capacity of the transmission tower foundation under wind load;

[0100] The module for determining the degree of reduction in bearing capacity is used to obtain the degree of change in the wave velocity value of the transmission tower foundation after a lightning strike in an actual project, and to determine the degree of reduction in the final bearing capacity of the transmission tower foundation after a lightning strike based on the degree of reduction in the bearing capacity of the transmission tower foundation considering the influence of horizontal loads after a lightning strike.

[0101] See also Figure 3 , the present invention also provides a device for evaluating the degree of reduction in the bearing capacity of a transmission tower foundation after a lightning strike, including a memory and a processor;

[0102] The memory is used to store computer program code and transmit the computer program code to the processor;

[0103] The processor is used to execute the above-mentioned method for evaluating the degree of reduction in the bearing capacity of the foundation of a transmission tower after a lightning strike according to the instructions in the computer program code.

[0104] The present invention also provides a computer-readable storage medium having a computer program stored thereon. When the computer program is executed by a processor, the method for evaluating the degree of reduction in the bearing capacity of a transmission tower foundation after a lightning strike as described above is implemented.

[0105] Generally speaking, the computer instructions for implementing the method of the present invention may be carried in any combination of one or more computer-readable storage media. Non-transitory computer-readable storage media may include any computer-readable media, except for the signal itself that is temporarily propagating.

[0106] The computer-readable storage medium may be, for example, but not limited to, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, device or device, or any combination thereof. More specific examples of computer-readable storage media (a non-exhaustive list) include: an electrical connection with one or more wires, a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EKROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination thereof. In the present invention, a computer-readable storage medium may be any tangible medium containing or storing a program that may be used by or in conjunction with an instruction execution system, device, or device.

[0107] Computer program code for performing the operation of the present invention can be written in one or more programming languages ​​or a combination thereof, including object-oriented programming languages ​​such as Java, Smalltalk, C++, and conventional procedural programming languages ​​such as "C" or similar programming languages, in particular, Python suitable for neural network computing and platform frameworks based on TensorFlow, PyTorch, etc. can be used. The program code can be executed entirely on the user's computer, partially on the user's computer, as an independent software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In the case of a remote computer, the remote computer can be connected to the user's computer or to an external computer (for example, using an Internet service provider to connect via the Internet) through any type of network, including a local area network (LAN) or a wide area network (WAN).

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

[0109] Although the embodiments of the present invention have been shown and described above, it should be understood that the above embodiments are exemplary and should not be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A method for evaluating the reduction degree of bearing capacity of a transmission tower foundation after a lightning strike, characterized in that: include: Conduct multiple groups of lightning tests on the transmission tower foundation using different current intensities, and measure the change in the wave velocity value of the transmission tower foundation before and after the lightning strike. Conduct uniaxial compression tests on the transmission tower foundation concrete before and after the lightning strike to obtain the uniaxial compressive strength and the change in uniaxial compressive strength, and establish a functional relationship between the change in wave velocity value and the change in uniaxial compressive strength. According to the results of multiple groups of lightning strike tests, multiple transmission tower foundation numerical models are established, and the overlying load of each transmission tower foundation numerical model is changed until the load corresponding to the stress value of the transmission tower foundation numerical model reaches the respective uniaxial compressive strength is the allowable overlying load; The allowable overburden load is applied to the top of each transmission tower foundation numerical model, the seismic wave is input at the bottom of the transmission tower foundation numerical model, and the allowable overburden load is continuously reduced until the inclination of the transmission tower foundation numerical model under the action of the seismic wave reaches the threshold value. The allowable overburden load corresponding to the threshold value is the first critical overburden load. The reduction degree of the bearing capacity of the transmission tower foundation under the action of the seismic wave is calculated according to the first critical overburden load, and the functional relationship between the reduction degree of the bearing capacity of the transmission tower foundation under the action of the seismic wave and the change degree of the uniaxial compressive strength is established; The overburden load is allowed to be applied to the top of each transmission tower foundation numerical model, and the wind load is applied to the top of the transmission tower foundation numerical model at the same time, and the allowed overburden load is continuously reduced until the inclination of the transmission tower foundation numerical model under the wind load reaches a threshold value. The allowed overburden load corresponding to the threshold value is the second critical overburden load. The reduction degree of the transmission tower foundation bearing capacity under the wind load is calculated according to the second critical overburden load, and a functional relationship between the reduction degree of the transmission tower foundation bearing capacity under the wind load and the change degree of the uniaxial compressive strength is established; According to the functional relationship between the wave velocity value change and the uniaxial compressive strength change, and the functional relationship between the reduction of the bearing capacity of the transmission tower foundation under the action of earthquake waves and the uniaxial compressive strength change, a functional relationship between the wave velocity value change and the reduction of the bearing capacity of the transmission tower foundation under the action of earthquake waves is established; according to the functional relationship between the wave velocity value change and the uniaxial compressive strength change, and the functional relationship between the reduction of the bearing capacity of the transmission tower foundation under the action of wind load and the uniaxial compressive strength change, a functional relationship between the wave velocity value change and the reduction of the bearing capacity of the transmission tower foundation under the action of wind load is established; according to the functional relationship between the wave velocity value change and the reduction of the bearing capacity of the transmission tower foundation under the action of earthquake waves, and the functional relationship between the wave velocity value change and the reduction of the bearing capacity of the transmission tower foundation under the action of wind load, the reduction of the bearing capacity of the transmission tower foundation after lightning strike considering the influence of horizontal load is obtained; The change of the wave velocity value of the transmission tower foundation after the lightning strike in the actual project is obtained, and the degree of reduction in the final bearing capacity of the transmission tower foundation after the lightning strike is determined according to the reduction in the bearing capacity of the transmission tower foundation considering the influence of horizontal load after the lightning strike.

2. The method for evaluating the reduction degree of the foundation bearing capacity of a transmission tower after a lightning strike according to claim 1 is characterized in that: The method of establishing multiple transmission tower foundation numerical models according to multiple groups of lightning strike test results includes: A unit numerical model was established in the discrete element software PFC to simulate the uniaxial compression test. The mesoscopic parameters under each group of lightning strike tests were determined by comparing and calibrating the uniaxial compression test curves and uniaxial compressive strength of the transmission tower foundation concrete after lightning strikes in multiple groups of lightning strike tests. A variety of transmission tower foundation numerical models are established, and the mesoscopic parameters determined under each set of lightning strike tests are assigned to the particles and contacts of each transmission tower foundation numerical model established.

3. The method for evaluating the reduction degree of the foundation bearing capacity of a transmission tower after a lightning strike according to claim 1 is characterized in that: The reduction degree of the bearing capacity of the transmission tower foundation under the action of the earthquake wave ΔF i e for: Where F0 is the engineering design load of the transmission tower foundation; F i e is the i-th first critical overburden load; The reduction degree of the bearing capacity of the transmission tower foundation under the wind load is ΔF i w for: In the formula, F i w is the i-th second critical overburden load.

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

5. The method for evaluating the reduction degree of the bearing capacity of the transmission tower foundation after a lightning strike according to claim 1 is characterized in that: The threshold value for the transmission tower foundation inclination is 0.5%.

6. The method for evaluating the reduction degree of the bearing capacity of the transmission tower foundation after a lightning strike according to claim 1 is characterized in that: Determining the degree of reduction in the ultimate bearing capacity of the transmission tower foundation after a lightning strike includes: Record the ratio of the total number of microcracks to the number of contacts in the numerical model of the transmission tower foundation when the critical overburden load is applied under different lightning tests; the critical overburden load is {F i e , F i w } min , where F i e is the ith first critical overburden load, F i w is the i-th second critical overburden load; When the rate of increase of the ratio is r s Greater than the rate of increase of the uniaxial compressive strength change r u When , the reduction adjustment coefficient β is calculated using the following formula: β＝1+(r s -r u )； The reduction degree of the transmission tower foundation bearing capacity after lightning strike considering the influence of horizontal load is multiplied by the reduction degree adjustment coefficient to obtain the final reduction degree of the transmission tower foundation bearing capacity after lightning strike.

7. The method for evaluating the reduction degree of the foundation bearing capacity of a transmission tower after a lightning strike according to claim 6 is characterized in that: The rate of increase of the ratio r s for: In the formula, α n represents the ratio of the total number of microcracks to the number of contacts under the nth group of lightning tests; α1 represents the ratio of the total number of microcracks to the number of contacts under the first group of lightning tests; I n I represents the current intensity under the nth group of lightning tests, I1 represents the current intensity under the first group of lightning tests, and the current intensity increases from the first group of lightning tests to the nth group of lightning tests; The rate of increase of the uniaxial compressive strength change is r u for: In the formula, Δσ n It represents the variation of uniaxial compressive strength under the nth group of lightning strike tests; Δσ1 represents the variation of uniaxial compressive strength under the first group of lightning strike tests.

8. A device for evaluating the reduction degree of bearing capacity of a transmission tower foundation after a lightning strike, characterized in that: The device is applied to the method described in any one of claims 1 to 7, and the device comprises: The first calculation module is used to perform multiple groups of lightning strike tests on the transmission tower foundation using different current intensities, and measure the change of the wave velocity value of the transmission tower foundation before and after the lightning strike, and perform a uniaxial compression test on the transmission tower foundation concrete before and after the lightning strike to obtain the uniaxial compressive strength and the change of the uniaxial compressive strength, and establish a functional relationship between the change of the wave velocity value and the change of the uniaxial compressive strength; The second calculation module is used to establish multiple transmission tower foundation numerical models according to multiple groups of lightning test results, and change the overlying load of each transmission tower foundation numerical model until the load corresponding to the stress value of the transmission tower foundation numerical model reaches the respective uniaxial compressive strength as the allowable overlying load; The third calculation module is used to apply the allowable overburden load to the top of each transmission tower foundation numerical model, input the seismic wave at the bottom of the transmission tower foundation numerical model, and continuously reduce the allowable overburden load until the inclination of the transmission tower foundation numerical model under the action of the seismic wave reaches a threshold value. The allowable overburden load corresponding to the threshold value is the first critical overburden load, and the reduction degree of the transmission tower foundation bearing capacity under the action of the seismic wave is calculated according to the first critical overburden load, and the function of the reduction degree of the transmission tower foundation bearing capacity under the action of the seismic wave and the change degree of the uniaxial compressive strength is established. numerical relationship; applying the allowable overburden load to the top of each transmission tower foundation numerical model, and applying the wind load to the top of the transmission tower foundation numerical model at the same time, and continuously reducing the allowable overburden load until the inclination of the transmission tower foundation numerical model under the wind load reaches the threshold value, and the allowable overburden load corresponding to the threshold value is the second critical overburden load, and the reduction degree of the transmission tower foundation bearing capacity under the wind load is calculated according to the second critical overburden load, and the functional relationship between the reduction degree of the transmission tower foundation bearing capacity under the wind load and the change degree of the uniaxial compressive strength is established; The fourth calculation module is used to establish a functional relationship between the wave velocity change and the reduction of the bearing capacity of the transmission tower foundation under the action of earthquake waves according to the functional relationship between the wave velocity change and the uniaxial compressive strength change and the functional relationship between the reduction of the bearing capacity of the transmission tower foundation under the action of earthquake waves and the uniaxial compressive strength change; establish a functional relationship between the wave velocity change and the reduction of the bearing capacity of the transmission tower foundation under wind load according to the functional relationship between the wave velocity change and the uniaxial compressive strength change and the uniaxial compressive strength change; obtain the reduction of the bearing capacity of the transmission tower foundation after lightning strike considering the influence of horizontal load according to the functional relationship between the wave velocity change and the reduction of the bearing capacity of the transmission tower foundation under earthquake waves and the wave velocity change and the reduction of the bearing capacity of the transmission tower foundation under wind load; The module for determining the degree of reduction in bearing capacity is used to obtain the degree of change in the wave velocity value of the transmission tower foundation after a lightning strike in an actual project, and to determine the degree of reduction in the final bearing capacity of the transmission tower foundation after a lightning strike based on the degree of reduction in the bearing capacity of the transmission tower foundation considering the influence of horizontal loads after a lightning strike.

9. A device for evaluating the reduction degree of bearing capacity of a transmission tower foundation after a lightning strike, characterized in that: including memory and processor; The memory is used to store computer program code and transmit the computer program code to the processor; The processor is configured to execute the method according to any one of claims 1 to 7 according to instructions in the computer program code.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the method according to any one of claims 1 to 7 is implemented.

Images