Method for evaluating anti-sliding stability of pile foundation of power transmission tower on slope under rainfall condition

Abstract

This invention discloses a method for evaluating the anti-sliding stability of transmission tower pile foundations on slopes under rainfall conditions. The method decomposes the stability evaluation problem of transmission tower foundations under rainfall-induced landslide conditions into several sub-problems: First, the basic parameters of the slope and future rainfall information released by the meteorological station are obtained to determine the shear strength parameters of the slope soil after rainfall time t. Based on these parameters, a numerical method is used to determine the stability state of the slope. If the slope is unstable, the relative position of the foundation and the potential sliding surface is first determined. If the foundation is above the potential sliding surface, the transmission tower will fail. If the foundation is partially below the potential sliding surface, the rotation angle of the foundation is calculated based on the soil conditions at the bottom of the foundation. The stability of the transmission tower is then determined according to the maximum allowable tilt value of the transmission tower specified in the "Operation Regulations for Overhead Transmission Lines".

Description

Technical Field

[0001] This invention relates to the field of safety assessment technology for transmission tower foundations on slopes under rainfall conditions, and specifically to an evaluation method for the anti-sliding stability of transmission tower pile foundations on slopes under rainfall conditions. Background Technology

[0002] Transmission towers, as a crucial component of power transmission infrastructure, are directly related to the reliability of power supply. Numerous transmission towers have been constructed in mountainous areas of my country prone to frequent rainfall. Rainfall is a significant factor in triggering landslides, which have already caused damage to numerous infrastructure projects, including transmission towers. Therefore, how to provide early warnings of rainfall-induced landslides and rationally assess their impact on various infrastructures remains a hot topic in landslide research. Effectively assessing the impact of rainfall-induced landslides on the stability of transmission towers is of great importance to ensuring the normal operation of the power grid.

[0003] Currently, many scholars both domestically and internationally, when studying rainfall-induced landslides, comprehensively consider information such as slope topography, rainfall data, and satellite positioning to propose corresponding landslide early warning methods. Some researchers use rainfall forecast information and a statistical model established through the Weibull distribution to obtain the probability density of rainfall-induced soil and rock landslides. Based on a theoretical model of landslide-induced tower deformation, they obtain the equivalent impact force acting on the transmission tower and the deflection at the top of the tower. Multiplying the landslide probability density with the probability density of landslide-induced tower deformation yields the probability of transmission line damage. Other researchers integrate information such as BeiDou satellite positioning, numerical weather prediction, and tower structural parameters to construct models for the probability of damage caused by landslide displacement and impact, quantifying the influencing factors. Some researchers have proposed a real-time monitoring device for the stability of transmission tower foundations to ensure the safe operation of transmission lines. These monitoring devices typically require routine inspections twice a month, significantly increasing the workload for monitoring and inspection. Furthermore, the monitoring devices also suffer from high costs in laying and maintaining the lines. Some researchers have proposed establishing a finite element model of the transmission tower-line-foundation coupled system, but this method has problems such as complex modeling and low computational efficiency, and therefore is not suitable for large-scale promotion. Summary of the Invention

[0004] Existing research analyzes the landslide resistance of transmission lines using theoretical models, field monitoring, and detailed numerical models. However, these methods often suffer from drawbacks such as insufficient prediction accuracy, high economic costs, and difficulty in improving computational efficiency. This invention, by acquiring rainfall information, slope parameters, and transmission tower parameters, comprehensively utilizes this information to accurately and rapidly evaluate the anti-slide stability of transmission tower foundations under rainfall conditions. By combining existing theoretical models and numerical analysis methods, a faster and more effective evaluation method for the anti-slide stability of transmission tower pile foundations on slopes under rainfall conditions is found, thus providing a valid reference for the normal operation of transmission towers on slopes.

[0005] To solve the above-mentioned technical problems, the present invention is achieved through the following technical solution:

[0006] A method for evaluating the anti-sliding stability of transmission tower foundations on slopes under rainfall conditions includes the following steps:

[0007] Step 1: Based on rainfall information and geological survey data, establish the relationship between rainfall time and the shear strength of slope soil and rock mass using empirical formulas and indoor test methods;

[0008] Step 2: Based on the soil and rock parameters and slope dimensions corresponding to a certain rainfall time, establish a numerical calculation model of the slope, conduct numerical analysis to determine the stability of the slope and obtain the sliding force of the landslide body;

[0009] Step 3: For foundations whose bottom is supported on the soil, the entire foundation is treated as a Winkler elastic foundation beam. The support conditions at the bottom of the foundation are simplified to hinged supports. It is assumed that the relationship between the foundation side and the soil is replaced by a series of independent springs. The subgrade coefficient is determined by the m-method to obtain the rotation angle and displacement of the foundation under the action of the landslide.

[0010] Step 4: For rock-socketed foundations, the portion of the foundation above the sliding surface is simplified as a cantilever beam, and the portion below the sliding surface is considered as a Winkler elastic foundation beam. The rotation angle generated by the foundation is calculated according to Step 3.

[0011] Step 5: Compare the foundation rotation angle and displacement calculated in the above steps with the limits specified in relevant specifications (such as the "Operation Regulations for Overhead Transmission Lines") to determine the anti-slip stability of the transmission tower foundation.

[0012] Furthermore, step 1 specifically includes:

[0013] The influence of water content on shear strength of unsaturated soil is mainly reflected through effective cohesion, internal friction angle and matrix suction. The relationship between shear strength parameters and water content is determined by empirical formulas.

[0014] The formula for the shear strength of unsaturated soil is:

[0015]

[0016]

[0017] In the formula, τ f σ' represents the shear strength of unsaturated soil, in Pa; c represents the total cohesion, in Pa; σ′ represents the effective stress, in Pa. c′ is the internal friction angle of the soil, in °; c′ is the effective cohesion, in Pa; μ s This represents the matric suction of the soil, measured in Pa. The internal friction angle varies with the matrix suction, and the unit is °.

[0018] The fitted curve showing the relationship between the shear strength of unsaturated soil and the matric suction and water content is expressed as follows:

[0019]

[0020]

[0021]

[0022] Where: c is the soil cohesion after rainfall duration t, Pa; w1 is the soil moisture content after rainfall duration t; Let be the internal friction angle of the soil after rainfall duration t; A, B, E, F, G and I are coefficients to be determined.

[0023] Assume the relationship between water content, infiltration intensity, and rainfall duration is as follows:

[0024] w1=ηet+w0

[0025] In the formula, w0 is the initial water content of the soil; η is a parameter to be determined, in mm. -1 e represents rainfall infiltration intensity, mm / s; t represents rainfall duration, s;

[0026] Furthermore, step 2 specifically includes:

[0027] A slope model is established based on actual geological conditions. Soil parameters are input after rainfall duration t, boundary conditions are set, and the stability of the slope is determined by observing the changes in the plastic zone. If the plastic zone extends from the toe of the slope to the top platform, it indicates that the slope is unstable.

[0028] The sliding force of a landslide is calculated by multiplying the horizontal acceleration of each element within the foundation width of the downstream slope at rainfall time t by the element's mass and then summing the results.

[0029]

[0030] In the formula: b and l0 are the foundation width and the embedment depth of the foundation above the sliding surface, respectively, in meters (m); i and a i These are the mass and acceleration of the i-th element within the landslide mass within the affected area, respectively, in kg and m / s². 2 F and q represent the impact force and impact pressure exerted on the foundation, respectively, with units of N and N / m. 2 It is assumed that the impact pressure is uniformly distributed along the burial depth.

[0031] Furthermore, step 3 specifically includes:

[0032] In the horizontal direction, the relationship between the pile and the soil is described using the Winkler foundation beam model, which assumes that a series of springs replace the soil. The foundation deflects under the action of the sliding force F and the horizontal resistance p of the soil, and its deflection differential equation is expressed as:

[0033]

[0034] In the formula, w is the basic deflection; E is the elastic modulus of the basic material; and I is the basic moment of inertia of the cross section.

[0035] According to Winkler's assumption, the resistance p of the foundation soil acting on the foundation is expressed by the following formula:

[0036] p = kw

[0037] In the formula: k is the bed coefficient, with units of N / m 3

[0038] It is usually assumed that the horizontal resistance coefficient of the foundation side is k = mx n This invention uses the m-method to solve the foundation deflection. In the m-method, k = mx, and the value of m is recommended according to JGJ 94-2008 "Technical Specification for Building Pile Foundations".

[0039] According to the m-method, the deflection differential equation is expressed as:

[0040]

[0041] make The above expression is then expressed as 'a' is the horizontal deformation coefficient, in meters (m). -1

[0042] The simplified expressions for the displacement and rotation of each section of the foundation are obtained by integrating with a power series as follows:

[0043]

[0044]

[0045] In the formula: w x Basic displacement; Basic turning angle; A x B x Based on the displacement coefficient, The rotation coefficient is based on the values ​​recommended in JGJ 94-2008 "Technical Specification for Building Pile Foundations";

[0046] Furthermore, step 4 specifically includes:

[0047] When the foundation bottom is fixed, the boundary conditions are substituted into the deflection differential equation obtained based on the m-method, and the rotation coefficient is found in the specification.

[0048]

[0049] In the formula: Basic corner; The basic rotation angle coefficient; l0 is the base length above the sliding surface, in meters;

[0050] Furthermore, step 5 specifically includes:

[0051] Relevant standards include the "Operation Regulations for Overhead Transmission Lines," which determine the stability of transmission towers based on the maximum allowable tilt value of transmission towers specified in the "Operation Regulations for Overhead Transmission Lines."

[0052] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0053] 1) The stability problem of transmission tower foundation induced by rainfall-induced landslide is decomposed into the stability problem of slope under rainfall conditions and the effect of landslide on transmission tower foundation. It comprehensively utilizes the advantages of theoretical analysis and numerical analysis methods, realizes the decoupling of complex problems, and has the characteristics of simple analysis process and strong applicability of analysis method.

[0054] 2) Numerical methods are used to determine the stability of the slope during rainfall, monitor the development of the plastic zone of the slope in real time, and use simplified analysis methods to calculate the effect of the sliding body on the transmission tower foundation. Compared with the overall calculation model based on the transmission tower foundation-slope, it has significantly higher computational efficiency.

[0055] 3) Traditional monitoring methods require real-time monitoring and the transmission and comprehensive analysis of large amounts of monitoring data, which leads to significant economic and analytical costs. This invention combines empirical formulas, numerical simulations, and theoretical models, integrating information such as weather forecasts, tower foundation parameters, and slope soil parameters, to achieve a rapid evaluation of the stability of transmission tower foundations on slopes under rainfall conditions. Attached Figure Description

[0056] Figure 1 This is a flowchart of the present invention;

[0057] Figure 2 This is a diagram illustrating the stress distribution of a foundation based on the Winkler beam model, where the bottom of the foundation is considered hinged, using the subgrade coefficient method.

[0058] Figure 3 This is a schematic diagram of the foundation stress based on the Winkler beam model, where the bottom of the foundation is considered as a fixed constraint, using the subgrade coefficient method.

[0059] Figure 4 This is a diagram showing the changes in the plastic zone of a slope under different rainfall durations;

[0060] Figure 5 This is a numerical calculation cloud map of the tower foundation, in which... Figure 5 a is the horizontal displacement contour map calculated by the numerical method for the foundation of tower #1. Figure 5 b is the horizontal displacement cloud diagram calculated by the numerical method for the foundation of tower #2. Detailed Implementation

[0061] To enable those skilled in the art to better understand the technical solutions of the present invention, preferred embodiments of the present invention are described below in conjunction with specific examples. However, it should be understood that the accompanying drawings are for illustrative purposes only and should not be construed as limiting the scope of this patent. For better illustration of this embodiment, some components in the drawings may be omitted, enlarged, or reduced, and do not represent the actual product dimensions. It is understandable that some well-known methods for evaluating the anti-slip stability of transmission tower pile foundations on slopes under rainfall conditions and their descriptions may be omitted in the accompanying drawings. The positional relationships described in the accompanying drawings are for illustrative purposes only and should not be construed as limiting the scope of this patent.

[0062] like Figure 1-3 As shown, this invention provides a rapid evaluation method for the anti-sliding stability of transmission tower foundations on slopes under rainfall conditions, comprising the following steps:

[0063] Step 1: Based on rainfall information and geological survey data, establish the relationship between rainfall time and the shear strength of slope soil and rock mass using empirical formulas and indoor test methods;

[0064] Step 2: Based on the soil and rock parameters and slope dimensions corresponding to a certain rainfall time, establish a numerical calculation model of the slope, conduct numerical analysis to determine the stability of the slope and obtain the sliding force of the landslide body;

[0065] Step 3: For foundations whose bottom is supported on the soil, the entire foundation is treated as a Winkler elastic foundation beam. The support conditions at the bottom of the foundation are simplified to hinged supports. It is assumed that the relationship between the foundation side and the soil is replaced by a series of independent springs. The subgrade coefficient is determined by the m-method, and the rotation angle and displacement of the foundation under the action of the landslide are obtained.

[0066] Step 4: For the rock-socketed foundation, the part above the sliding surface of the foundation is simplified as a cantilever beam, and the part below the sliding surface is regarded as a Winkler elastic foundation beam. The rotation angle generated by the foundation is calculated according to the deflection differential equation obtained in Step 3.

[0067] Step 5: Compare the foundation rotation angle and displacement calculated in the above steps with the limits specified in relevant specifications (such as the "Operation Regulations for Overhead Transmission Lines") to determine the anti-slip stability of the transmission tower foundation.

[0068] Furthermore, step 1 specifically includes:

[0069] The influence of water content on shear strength of unsaturated soil is mainly reflected through effective cohesion, internal friction angle and matrix suction. The relationship between shear strength parameters and water content is determined by empirical formulas.

[0070] The formula for the shear strength of unsaturated soil is:

[0071]

[0072]

[0073] In the formula, τ f σ' represents the shear strength of unsaturated soil, in Pa; c represents the total cohesion, in Pa; σ′ represents the effective stress, in Pa. c′ is the internal friction angle of the soil, in °; c′ is the effective cohesion, in Pa; μ s This represents the matric suction of the soil, measured in Pa. The internal friction angle varies with the matrix suction, and the unit is °.

[0074] The fitted curve showing the relationship between the shear strength of unsaturated soil and the matric suction and water content is expressed as follows:

[0075]

[0076]

[0077]

[0078] Where: c is the soil cohesion after rainfall duration t, Pa; w1 is the soil moisture content after rainfall duration t; Let be the internal friction angle of the soil after rainfall duration t; A, B, E, F, G and I are coefficients to be determined.

[0079] Assume the relationship between water content, infiltration intensity, and rainfall duration is as follows:

[0080] w1=ηet+w0

[0081] In the formula, w0 is the initial water content of the soil; η is a parameter to be determined, in mm. -1 e represents the rainfall infiltration intensity, mm / s; t represents the rainfall duration, s.

[0082] Furthermore, step 2 specifically includes:

[0083] A slope model is established based on actual geological conditions. Soil parameters are input after rainfall duration t, boundary conditions are set, and the stability of the slope is determined by observing the changes in the plastic zone. If the plastic zone extends from the toe of the slope to the top platform, it indicates that the slope is unstable.

[0084] The sliding force of a landslide is calculated by multiplying the horizontal acceleration of each element within the foundation width of the downstream slope at rainfall time t by the element's mass and then summing the results.

[0085]

[0086] In the formula: b and l0 are the foundation width and the embedment depth of the foundation above the sliding surface, respectively, in meters (m); i and a i These are the mass and acceleration of the i-th element within the landslide mass within the affected area, respectively, in kg and m / s². 2 F and q represent the impact force and impact pressure exerted on the foundation, respectively, with units of N and N / m. 2 It is assumed that the impact pressure is uniformly distributed along the burial depth.

[0087] Furthermore, step 3 specifically includes:

[0088] In the horizontal direction, the relationship between the pile and the soil is described using the Winkler foundation beam model, which assumes that a series of springs replace the soil. The foundation deflects under the action of the sliding force F and the horizontal resistance p of the soil, and its deflection differential equation is expressed as follows:

[0089]

[0090] In the formula, w is the basic deflection; E is the elastic modulus of the basic material; and I is the basic moment of inertia of the cross section.

[0091] According to Winkler's assumption, the resistance p of the foundation soil acting on the foundation is expressed by the following formula:

[0092] p = kw

[0093] In the formula: k is the bed coefficient, with units of N / m 3

[0094] It is usually assumed that the horizontal resistance coefficient of the foundation side is k = mx n This invention uses the m-method to solve the foundation deflection. In the m-method, k = mx, and the value of m is recommended according to JGJ 94-2008 "Technical Specification for Building Pile Foundations".

[0095] According to the m-method, the deflection differential equation is expressed as:

[0096]

[0097] make The above expression is then expressed as 'a' is the horizontal deformation coefficient, in meters (m). -1

[0098] The simplified expressions for the displacement and rotation of each section of the foundation are obtained by integrating with a power series as follows:

[0099]

[0100]

[0101] In the formula: w x Basic displacement; Basic turning angle; A x B x Based on the displacement coefficient, The rotation coefficient is based on the values ​​recommended in JGJ 94-2008 "Technical Specification for Building Pile Foundations".

[0102] Furthermore, step 4 specifically includes:

[0103] When the foundation bottom is fixed, the boundary conditions are substituted into the deflection differential equation obtained based on the m-method, and the rotation coefficient is found in the specification.

[0104]

[0105] In the formula: Basic corner; The basic rotation coefficient; l0 is the basic length above the sliding surface, in meters.

[0106] Furthermore, step 5 specifically includes:

[0107] Compare the angle of the foundation top calculated in steps 3 and 4 with the maximum tilt angle specified in the "Operation Regulations for Overhead Transmission Lines": the maximum tilt angle for towers with a height of 50m and above is 0.5%, and the maximum tilt angle for towers with a height of less than 50m is 1.0%.

[0108] The following is in conjunction with the appendix Figure 4-5 The present invention will be further described in detail with reference to specific embodiments to facilitate a clear understanding of the present invention, but these embodiments do not constitute a limitation on the present invention.

[0109] The stability of a transmission tower in a certain area was evaluated and tested using the method disclosed in this invention. This area is located in a subtropical rainy region, and the foundation type is pile foundation. The surface parameters around the transmission tower are shown in Table 1 below.

[0110] Table 1

[0111]

[0112] The parameters of the rock at the bottom of the foundation are shown in Table 2 below:

[0113] Table 2

[0114] <![CDATA[γ / (kN / m 3 )]]> E / (GPa) ν 30000 30 0.2

[0115] The soil within the foundation depth range of the transmission towers is mainly plastic cohesive soil with a liquid limit of about 50%. The bottom of the foundation of tower #1 is located above the soil, while tower #2 has a rock-embedded foundation. The basic parameters are shown in Table 3 below:

[0116] Table 3

[0117]

[0118] After continuous low-intensity rainfall, the soil absorbs moisture and its shear strength decreases, creating a potential sliding surface on the slope. The foundation is located below the potential sliding surface, and the soil beneath the foundation remains unchanged.

[0119] The relationship between rainfall time t and soil shear strength is established using the parameters in the table above:

[0120] w1 = 1.5 × 10 -7 t+0.21

[0121] c = -18.4w1 + 448.4

[0122]

[0123] Table 4 shows the shear strength of soil on slopes affected by rainfall.

[0124]

[0125] like Figure 4As shown, the plastic zone extends from the bottom to the top platform as the rainfall duration increases, and the plastic zone is completely connected when the rainfall time reaches 33 hours. Secondly, the trend of slope top displacement with time step can be observed. When the rainfall time is 33 hours, the slope top displacement is in an unstable state.

[0126] The equivalent load F of the soil portion within the foundation width of the upstream slope is 1507 kN. For tower #1 in Table 2, the foundation is an excavation-backfill type foundation. The soil around and at the bottom of the foundation is mainly gravelly soil. According to JGJ 94-2008 "Technical Specification for Building Pile Foundations", the horizontal resistance coefficient m of the foundation soil can be taken as 8MN / m. 4 .

[0127] Basic horizontal deformation coefficient

[0128] The corner of the foundation of tower #1

[0129]

[0130] The corner of the foundation of tower #2

[0131]

[0132] According to the operation standards for towers and foundations in the "Operation Regulations for Overhead Transmission Lines", the maximum allowable tilt of angle steel towers and straight towers of 50m and above is 0.5%, and the maximum allowable tilt of towers below 50m is 1%.

[0133] Therefore, under these rainfall conditions, the tilt of the foundations of towers #1 and #2 exceeds the allowable value specified in the regulations. Power grid maintenance personnel should pay attention to the landslide risks around the towers and keep track of changes in the landslide status in the area.

[0134] To verify the accuracy of this invention in calculating the rotation angle of transmission tower foundations on a rainfall-affected slope, a slope-based transmission tower foundation model was established using ABAQUS to verify the theoretical calculation results. The rotation angles of tower foundations #1 and #2 under rainfall were calculated. The results are shown in Table 5 below, and the numerical calculation cloud diagrams of the tower foundations are as follows. Figure 5 As shown.

[0135] Table 5

[0136]

[0137] In summary, this invention discloses a rapid evaluation method for the anti-sliding stability of transmission tower foundations under rainfall-induced landslide conditions. The method decomposes the stability evaluation problem of transmission tower foundations under rainfall-induced landslide conditions into several sub-problems: First, the basic parameters of the slope and future rainfall information released by the meteorological station are obtained to determine the shear strength parameters of the slope soil after rainfall time t. Based on these parameters, numerical methods are used to determine the stability state of the slope. If the slope is unstable, the relative position of the foundation and the potential sliding surface is first determined. If the foundation is above the potential sliding surface, the transmission tower will fail. If part of the foundation is below the potential sliding surface, the rotation angle of the foundation is calculated based on the soil conditions at the bottom of the foundation. The stability of the transmission tower is then determined according to the maximum allowable tilt value of the transmission tower specified in the "Operation Regulations for Overhead Transmission Lines".

[0138] The above description is merely a preferred embodiment of the present invention, but the present invention is not limited to the specific embodiments described above. Those skilled in the art can make various modifications, additions, or substitutes with similar methods without departing from the principles of the present invention, and these should also be considered within the scope of protection of the present invention.

Claims

1. A method for evaluating the anti-sliding stability of transmission tower pile foundations on slopes under rainfall conditions, characterized in that, include: Step 1: Based on rainfall information and geological survey data, establish the relationship between rainfall time and the shear strength of slope soil and rock mass using empirical formulas and indoor test methods; Step 2: Based on the soil and rock parameters and slope dimensions corresponding to the rainfall time, establish a numerical calculation model of the slope, conduct numerical analysis to determine the stability of the slope and obtain the sliding force of the landslide body. Step 3: For foundations whose bottom is supported on the soil, the entire foundation is treated as a Winkler elastic foundation beam. The support conditions at the bottom of the foundation are simplified to hinged supports. It is assumed that the relationship between the foundation side and the soil is replaced by a series of independent springs. The subgrade coefficient is determined by the m-method to obtain the rotation angle and displacement of the foundation under the action of the landslide. Step 4: For the rock-socketed foundation, the part of the foundation above the sliding surface is simplified as a cantilever beam, and the part of the foundation below the sliding surface is regarded as a Winkler elastic foundation beam. The rotation angle generated by the foundation is calculated according to Step 3. Step 5: Compare the foundation rotation angle and displacement calculated in the above steps with the limits specified in the relevant specifications to determine the anti-slip stability of the transmission tower foundation.

2. The method for evaluating the anti-sliding stability of the pile foundation of the power transmission tower on the slope under rainfall conditions according to claim 1, characterized in that: In step 1, the influence of the water content of unsaturated soil on shear strength is mainly reflected through effective cohesion, internal friction angle and matrix suction. The relationship between shear strength parameters and water content is determined by empirical formulas. The formula for the shear strength of unsaturated soil is: In the formula, τ f σ' represents the shear strength of unsaturated soil, in Pa; c represents the total cohesion, in Pa; σ′ represents the effective stress, in Pa. c′ is the internal friction angle of the soil, in °; c′ is the effective cohesion, in Pa; μ s This represents the matric suction of the soil, measured in Pa. The internal friction angle varies with the matrix suction, in degrees. The fitted curve showing the relationship between the shear strength of unsaturated soil and the matric suction and water content is expressed as follows: Where: c is the soil cohesion after rainfall duration t, Pa; w1 is the soil moisture content after rainfall duration t; Let be the internal friction angle of the soil after rainfall duration t; A, B, E, F, G, and I are coefficients to be determined. Assume the relationship between water content, infiltration intensity, and rainfall duration is as follows: w1=ηet+w0 In the formula, w0 is the initial water content of the soil; η is a parameter to be determined, in mm. -1 e represents the rainfall infiltration intensity in mm / s; t represents the rainfall duration in seconds.

3. The method for evaluating the anti-sliding stability of transmission tower pile foundations on slopes under rainfall conditions as described in claim 1, characterized in that: In step 2, a slope model is established based on the actual geological conditions. Soil parameters after rainfall duration t are input, boundary conditions are set, and the stability of the slope is determined by observing the changes in the plastic zone. If the plastic zone extends from the toe of the slope to the top platform, it indicates that the slope is unstable. The sliding force of a landslide is calculated by multiplying the horizontal acceleration of each element within the foundation width of the downstream slope at rainfall time t and then summing the results, i.e.: In the formula: b and l0 are the foundation width and the embedment depth of the foundation above the sliding surface, respectively, in meters (m); i and a i These are the mass and acceleration of the i-th element within the landslide mass within the affected area, respectively, in kg and m / s². 2 F and q represent the impact force and impact pressure exerted on the foundation, respectively, with units of N and N / m. 2 It is assumed that the impact pressure is uniformly distributed along the burial depth.

4. The method for evaluating the anti-sliding stability of the pile foundation of the power transmission tower on the slope under rainfall conditions according to claim 1, characterized in that: In step 3, the relationship between the pile and the soil in the horizontal direction is described using the Winkler foundation beam model. This method assumes that a series of springs replace the soil and the foundation. The foundation deflects under the action of the sliding force F and the horizontal resistance p of the soil, and its deflection differential equation is expressed as: In the formula, w is the basic deflection; E is the elastic modulus of the basic material; and I is the basic moment of inertia of the cross section. According to Winkler's assumption, the resistance p of the foundation soil acting on the foundation is expressed by the following formula: p = kw wherein: k is the coefficient of the base, in N / m 3 ; The m-method is used to solve the foundation deflection. In the m-method, k = mx. According to the recommended values ​​for m in JGJ 94-2008 "Technical Code for Building Pile Foundations", the deflection differential equation can be expressed as follows: Let then the above expression is a is the horizontal deformation coefficient in m -1 ; The simplified expressions for the displacement and rotation of each section of the foundation are obtained by integrating with a power series as follows: In the formula: w x The basic displacement; Basic turning angle; A x B x Based on the displacement coefficient, The rotation coefficient is based on the values ​​recommended in JGJ 94-2008 "Technical Specification for Building Pile Foundations".

5. The method for evaluating the anti-sliding stability of transmission tower pile foundations on slopes under rainfall conditions as described in claim 1, characterized in that: In step 4, considering the bottom of the foundation as a fixed end, the boundary conditions are substituted into the deflection differential equation obtained based on the m-method, and the rotation coefficients in the specification are looked up: In the formula: Basic corner; The basic rotation coefficient; l0 is the basic length above the sliding surface, in meters.

6. The method for evaluating the anti-sliding stability of the pile foundation of the power transmission tower on the slope under rainfall conditions according to claim 1, characterized in that: In step 5, the relevant regulations include the "Operation Regulations for Overhead Transmission Lines". Based on the maximum allowable tilt value of the transmission tower specified in the "Operation Regulations for Overhead Transmission Lines", the stability of the transmission tower is determined.

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