A power transmission tower catchment area calculation method considering multi-factor influence

Abstract

A method for calculating the water catchment of transmission towers considering the influence of multiple factors includes the following steps: calculating the component shape coefficient; calculating the tower frame filling coefficient; calculating the projected area of ​​rainfall blocked by the tower; calculating the rainfall intensity P at the tower location; determining the rainfall angle α; determining the environmental calibration factor λ; calculating the water catchment of the transmission tower; and verifying the calculation through on-site monitoring. This invention provides a method for calculating the water catchment of transmission towers considering the influence of multiple factors, enabling accurate quantification of the water catchment of transmission towers during rainfall.

Description

Technical Field

[0001] This invention relates to the field of disaster prevention and mitigation for power transmission lines, and in particular to a method for calculating the water catchment of power transmission towers that takes into account the influence of multiple factors. It is mainly used to accurately calculate the amount of rainwater blocked by the tower materials during rainfall, to calculate the slope stability considering the water-blocking effect of the tower, to guide staff on whether it is necessary to improve the tower's anti-water-catchment measures, and thus prevent geological disasters such as landslides around the tower, ensuring the stable and safe operation of the power transmission tower and preventing tower collapse accidents. Background Technology

[0002] Under rainfall conditions, surface runoff and underground seepage interact in the area surrounding the tower foundations of transmission lines, forming a complex three-dimensional hydrodynamic network. Traditional two-dimensional catchment area methods often neglect transmission towers situated on slopes, leading to significant errors in estimating the actual runoff in the tower foundation area. In some locations, heavy rains have caused water accumulation at the tower bases, weakening the soil's mechanical properties. Furthermore, due to flawed catchment design, these towers have been subjected to concentrated runoff erosion during short-duration heavy rainfalls, ultimately resulting in the tower foundations being hollowed out and collapsing.

[0003] Currently, domestic research on water catchment calculation mainly focuses on providing accurate water catchment information for urban stormwater management, watershed planning, and topographic studies.

[0004] For example, Wang Haihan used a visual programming language to analyze and model rainfall runoff to form topographic point clouds. By obtaining the rainfall intensity of the region, he calculated the total precipitation in the runoff area, thus analyzing and calculating runoff in mountainous regions. This method, based on topographic point clouds, focuses on calculating the total macroscopic topographic runoff volume, but does not consider the obstruction and collection effects of man-made structures such as power transmission towers on local rainfall runoff, and cannot quantify the contribution of tower structures to runoff.

[0005] Yang Junyan used computer information technology to perform water catchment calculation and simulation based on three-dimensional surfaces, thus providing a quantitative method for analyzing the scale of water surfaces at the foot of mountains. This method is applicable to the assessment of natural surface water catchment, but it lacks targeted modeling of structural features such as the cross-sectional shape of lattice-type iron tower members and the tower filling rate, making it difficult to calculate the water catchment effect of the iron tower itself.

[0006] You Jinjun proposed a flow calculation method based on the identification of the relationship between the entire inflow (covering surface runoff, water use, and drainage), which calculates and categorizes natural runoff and user drainage separately. This method can improve the accuracy of design flow for water function zones and can also be quickly adjusted according to different cross-sectional divisions. This method is suitable for watershed-scale water resource management, but it does not incorporate the physical characteristics of transmission tower components and local environmental factors, and therefore cannot meet the calculation requirements for water runoff at transmission tower locations.

[0007] However, there is still a lack of methods for calculating water catchment in the construction of iron towers. Literature on iron tower water catchment calculation considers five influencing factors: tower shape, tower height, tower base opening, rainfall intensity, and rainfall angle, deriving formulas for calculating iron tower water catchment. When calculating water catchment volume, the catchment area is divided into two categories: in calm or light wind conditions, the catchment area is simplified to the tower foundation area, with each tower leg collecting 1 / 4 of the total catchment volume; in strong wind conditions, it is simplified to the area of ​​a triangle with the tower base opening as the base and the tower height as the height, with each tower leg collecting 1 / 2 of the total catchment volume. The derived formulas are then used to calculate the iron tower water catchment volume.

[0008] Existing methods for calculating water catchment generally focus on lateral water catchment analysis, primarily applied to macro-level scenarios such as urban stormwater management and watershed planning. For example, they utilize terrain point cloud modeling and 3D surface simulation techniques to achieve overall water catchment assessment. However, these methods lack targeted optimization for the water catchment characteristics of specific engineering structures such as power transmission towers, failing to integrate key factors like the physical characteristics of tower components, such as member shape and tower fill ratio. This makes it difficult to accurately quantify the local water catchment effect of the tower. Furthermore, existing methods for calculating tower water catchment also have significant shortcomings, considering only a few macro-level parameters such as tower shape and height, resulting in low calculation accuracy and a lack of experimental correction. Summary of the Invention

[0009] The technical problem to be solved by the present invention is to provide a method for calculating the water catchment of transmission towers that takes into account the influence of multiple factors, so as to achieve accurate quantification of the water catchment of transmission towers during rainfall.

[0010] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: A method for calculating the water catchment of transmission towers considering the influence of multiple factors includes the following steps: Step 1: Calculate the component shape coefficient ; Step 2: Calculate the tower frame filling coefficient ; Step 3: Calculate the projected area of ​​the rain-blocking tower; Step 4: Calculate the rainfall intensity P at the tower location; Step 5: Determine the rainfall angle α; Step 6: Determine the environmental calibration factor λ; Step 7: Calculate the water catchment volume of the transmission tower; Step 8: Verify through on-site monitoring.

[0011] In step 1, the circular cross-section rod... Values steel rods Values η is the shielding coefficient that takes into account the mutual interference between tower members.

[0012] In step 3, the transmission tower is divided into n segments from bottom to top, and the projected area of ​​each segment of the transmission tower that blocks rainfall is... and the projected area of ​​the entire iron tower blocking rainfall. The formulas (1) and (2) are used for calculation; (1); (2); In the formula: This refers to the filling coefficient of the iron tower structure. To calculate the height of the segment; The calculations are for the top and bottom widths of the tower body.

[0013] In step 5, the rainfall angle is determined based on wind conditions: 0° in windless conditions and 0° in windy conditions. The value is obtained through calculation using a formula; The standard value of wind load perpendicular to the raindrop surface is calculated using the following formula: (3); (4); In the formula: The standard value of wind load is the wind direction perpendicular to the surface of the raindrop; This is the coefficient for wind pressure height variation; The projected area of ​​the raindrop subjected to wind pressure; The reference wind pressure standard value; The average diameter of the raindrop; Reference wind pressure standard value The calculation formula is: (5); In the formula: The wind speed is based on a reference height of 10m; The formula for calculating the weight of a raindrop is: (6); In the formula: The weight of the raindrop; It is the acceleration due to gravity; The formula for calculating the weight of a raindrop is: (7); In the formula: The density of raindrops is the same as the density of pure water; The volume of the raindrop; The formula for calculating raindrop volume is: (8); Calculate the angle of rainfall under windy conditions The angle of rainfall in windy conditions is: (9).

[0014] In step 6, considering the non-uniformity of wind direction and speed around the transmission tower, as well as the influence of obstructions on the water catchment of the transmission tower, a calibration factor λ for the water catchment environment of the transmission tower is introduced, with λ ranging from 0.18 to 0.26.

[0015] In step 7, the water collection volume at the transmission tower location is... (10).

[0016] In step 8, the water catchment monitoring device is used to monitor the test tower location in real time, and the measured water catchment data and rainfall data of the transmission tower during the test are obtained. The obtained raw data are sorted and screened, and the actual data measured by the field test are used for calibration and correction.

[0017] The water collection monitoring device includes a rain trough that surrounds the four legs of the power transmission tower. One side of the rain trough is connected to the measuring water tank via a flow guide channel. A Parshall flume is installed inside the measuring water tank. A rigid frame is installed above the Parshall flume, and an ultrasonic probe is installed on the rigid frame. The ultrasonic probe is electrically connected to a flow meter.

[0018] The base platform and bottom of the measuring tank should be kept level.

[0019] The water flow rate is: ; In the formula: Q is the flow rate; H is the liquid level height; K and n are constants related to the throat width; The water level height H is: ; In the formula: D is the distance from the probe to the bottom of the channel; A is the speed of the ultrasonic wave in the air; t is the time difference between the ultrasonic wave transmission and reception; H is the liquid level in the Parshall flume.

[0020] This invention generally focuses on lateral water catchment analysis at the macroscopic topographic scale, lacking specific optimization for the concrete engineering structure of transmission towers. This results in an inability to accurately quantify the local water catchment effect of the towers. This invention addresses this by introducing core parameters such as the tower frame infill coefficient and component shape coefficient, allowing the model to directly relate to the specific structural characteristics of the tower. This shifts the focus from macroscopic watershed analysis to water catchment calculation specific to transmission towers, achieving the fundamental goal of computational preparation. Secondly, by introducing the tower frame infill coefficient and component shape coefficient, the physical characteristics of the tower itself are quantified. The infill coefficient uses differentiated values ​​based on the type of narrow-base towers (those with narrow bases and those with wide bases) and is corrected considering the influence of gusset plates. The component shape coefficient distinguishes between circular cross-section members and steel members to accurately reflect the differences in water catchment of different shaped components. Simultaneously, a projection area calculation method based on the segmented height and top and bottom width parameters of the tower body is used to accurately capture the spatial geometric characteristics of complex tower structures. Regarding environmental factors, the model system integrates rainfall intensity levels and rainfall angle parameters affected by wind speed and direction. It also innovatively introduces an environmental calibration factor, determined through fitting field test data. This factor corrects calculation deviations caused by complex environmental conditions such as irregular changes in wind speed and direction, significantly improving the agreement between theoretical calculations and measured data. Finally, the constructed comprehensive calculation formula achieves accurate quantification of water catchment in transmission towers, providing reliable technical support for slope stability assessment and protection engineering design. This includes factors such as tower frame filling coefficient, component shape coefficient, rainfall angle parameters, and environmental calibration factors.

[0021] This invention provides a method for calculating the water catchment of transmission towers that considers the influence of multiple factors, and has the following technical advantages: 1) The method for calculating the water catchment of transmission towers introduces the shape coefficient of the tower components, which reasonably considers the effect of the cross section of the transmission tower members on the collection of rainfall, as well as the difference in the collection of rainfall between transmission towers with circular cross section members and those with steel section members. This makes the calculation method applicable to both angle steel towers and steel pipe towers.

[0022] 2) The method for calculating the water catchment of transmission towers introduces the projected area of ​​rain-blocking. By calculating the tower outline area and the width of the windward side in segments, the influence of tower materials and node plates on rain-blocking is reasonably considered. Furthermore, the difference between narrow-base towers and wide-base towers is distinguished, reflecting the spatial geometric characteristics of the tower structure. This solves the problem of the traditional water catchment calculation method that simply equates the tower to a triangle.

[0023] 3) An environmental calibration factor correction method for water catchment calculation was proposed. The range of environmental calibration factor values ​​was determined through field monitoring test data, which effectively corrected the non-uniformity of wind direction and wind speed around the transmission tower, as well as the impact of obstructions on the water catchment of the transmission tower.

[0024] 4) A formula for calculating the rainfall angle has been established, which is more scientific and reasonable in taking into account the influence of wind on the tilt of the rainfall angle and the water runoff from the iron tower. Attached Figure Description

[0025] The present invention will be further described below with reference to the accompanying drawings and embodiments: Figure 1 This is a schematic diagram of the rainfall angle under windy conditions according to the present invention.

[0026] Figure 2 This is a schematic diagram of the water catchment monitoring device in this invention. Detailed Implementation

[0027] A method for calculating the water catchment of transmission towers considering the influence of multiple factors includes the following steps: Step 1: Calculate the component shape coefficient

[0028] The calculated shape factor of the member is used to correct for the differences in water collection characteristics between members with different cross-sectional shapes. For members with circular cross-sections, the value is taken as... The value of the steel member is taken as follows . or The values ​​are shown in Table 1, with intermediate values ​​obtained using linear interpolation; among them, b To calculate the segment width, h To calculate the height of the segment; or The value of the shielding coefficient, which takes into account the mutual interference between tower members, and the tower's fill factor are considered. and the aspect ratio of the segments b / w For details, please refer to Table 1.

[0029] Table 1

[0030] Step 2: Calculate the tower frame filling coefficient

[0031] The tower frame filling coefficient characterizes the density of the tower structure. Different benchmark values ​​are used according to the tower type: 0.2-0.3 for narrow-base tower body and tower head, and 0.15-0.2 for wide-base tower body. Furthermore, considering the influence of gusset plates, a correction factor of 1.2 is applied to narrow-base towers, and a correction factor of 1.1 is applied to wide-base towers.

[0032] Step 3: Calculate the projected area of ​​the tower blocking rainfall. The transmission tower is divided into n segments (n=1, 2, 3...) from bottom to top. The projected area of ​​each segment of the transmission tower that blocks rainfall is... and the projected area of ​​the entire iron tower blocking rainfall. The formulas (1) and (2) are used for calculation.

[0033] (1); (2); In the formula: This refers to the filling coefficient of the iron tower structure. This is used to calculate the height of the segment. The calculations are for the top and bottom widths of the tower body.

[0034] Step 4: Calculate the rainfall intensity P at the tower location.

[0035] The rainfall intensity at the tower location is obtained based on data from the meteorological monitoring equipment at the tower location.

[0036] Step 5: Determine the rainfall angle α.

[0037] The angle of rainfall is determined based on wind conditions; in windless conditions, the angle of rainfall is taken as 0°, and in windy conditions, the angle of rainfall is... The values ​​are obtained through calculation using a formula. The standard value of the wind load perpendicular to the raindrop surface is calculated using the following formula: (3); (4); In the formula: The standard value of wind load is the wind direction perpendicular to the surface of the raindrop; This is the coefficient for wind pressure height variation; The projected area of ​​the raindrop subjected to wind pressure; This is the benchmark wind pressure standard value.

[0038] The average diameter of the raindrop is taken from Table 2.

[0039] Table 2

[0040] Reference wind pressure standard value The calculation formula is: (5); In the formula: The wind speed is based on a reference height of 10m.

[0041] The formula for calculating the weight of a raindrop is: (6); In the formula: The weight of the raindrop; This is the acceleration due to gravity.

[0042] The formula for calculating the weight of a raindrop is: (7); In the formula: The density of raindrops is the same as the density of pure water; Let be the volume of the raindrop (considered as a sphere); The formula for calculating raindrop volume is: (8); Calculate the angle of rainfall under windy conditions The angle of rainfall in windy conditions is: (9); Step 6: Determine the environmental calibration factor λ.

[0043] To improve the accuracy of water catchment calculations, considering the non-uniformity of wind direction and speed around transmission towers, as well as the impact of obstructions on water catchment, a calibration factor λ for the water catchment environment of transmission towers is introduced.

[0044] Based on on-site water catchment monitoring experiments and the calculation and analysis of monitoring data, the recommended value for the environmental calibration factor λ is 0.18 to 0.26.

[0045] Step 7: Calculate the water catchment of the transmission tower.

[0046] The invention has been verified through on-site monitoring and the results are consistent with expectations.

[0047] By substituting all the determined parameters into the following formula, the water catchment volume of the corresponding transmission tower location can be calculated.

[0048] (10); A water catchment monitoring device was used to monitor the test tower site in real time, acquiring measured water catchment data and rainfall data for the transmission tower during the test. The obtained raw data was then processed and screened. Because there is currently limited research on water catchment in transmission towers both domestically and internationally, and no comprehensive method for calculating water catchment in transmission towers exists, the water catchment calculation method proposed in this invention still needs to be calibrated and corrected using actual data measured in field tests.

[0049] The formula for calculating catchment volume before introducing environmental calibration factors is as follows: (11); The water collection monitoring device includes rain troughs 1, constructed around the four bases of the tower according to the terrain. Starting from the outlet of the rain troughs 1, a guide channel 2 is constructed, sloping downwards and connecting at its end to a horizontal measuring trough 3. A standard-sized Parshall flume 4 is installed inside the measuring trough 3. All gaps between the Parshall flume 4 and the measuring trough 3 are densely filled with cement mortar to ensure that all the diverted water flows uniquely through the throat section of the Parshall flume. A rigid frame 5 is erected above the contraction section of the Parshall flume 4, and an ultrasonic probe 6 is installed on the rigid frame 5. The probe of the ultrasonic probe 6 faces the water surface in the trough below, and the ultrasonic probe 6 is connected to a flow meter 7.

[0050] Water level: ; In the formula: D: Distance from the ultrasonic probe 6 to the bottom of the channel (unit: A: Speed ​​of ultrasound in air (unit: ); t: Time difference between ultrasonic wave transmission and reception (unit: H: Liquid level height in the Parshall flume (unit: ).

[0051] The flow meter 7 has a built-in formula for calculating the water catchment flow rate as follows: ; Where: Q: flow rate (unit: H: Liquid level height (unit: K and n are constants related to the width of the throat.

[0052] The measured runoff volume and rainfall intensity, as well as the calculated runoff volume and environmental calibration factor before correction, are partially read and shown in Table 3.

[0053] Table 3

[0054] As can be seen from the data in Table 3, the environmental calibration factor l The measured values ​​ranged from 0.18 to 0.26. The theoretically calculated values ​​before correction were generally higher than the measured values, indicating a significant influence of environmental factors. Therefore, the introduction of... l It can then be effectively calibrated; l The value fluctuates slightly with the intensity of rainfall, but remains stable overall.

Claims

1. A method for calculating the water catchment of transmission towers considering the influence of multiple factors, characterized in that, Includes the following steps: Step 1: Calculate the component shape coefficient ; Step 2: Calculate the tower frame filling coefficient ; Step 3: Calculate the projected area of ​​the rain-blocking tower; Step 4: Calculate the rainfall intensity P at the tower location; Step 5: Determine the rainfall angle α; Step 6: Determine the environmental calibration factor λ; Step 7: Calculate the water catchment volume of the transmission tower; Step 8: Verify through on-site monitoring.

2. The method for calculating the water catchment of transmission towers considering the influence of multiple factors as described in claim 1, characterized in that: In step 1, the circular cross-section rod... Values steel rods Values , η It is the shielding coefficient that takes into account the mutual interference between the tower members.

3. The method for calculating the water catchment of transmission towers considering the influence of multiple factors as described in claim 1, characterized in that: In step 3, the transmission tower is divided into n segments from bottom to top, and the projected area of ​​each segment of the transmission tower that blocks rainfall is... and the projected area of ​​the entire iron tower blocking rainfall. The formulas (1) and (2) are used for calculation. In the formula: This refers to the filling coefficient of the iron tower structure. To calculate the height of the segment; The calculations are for the top and bottom widths of the tower body.

4. The method for calculating the water catchment of transmission towers considering the influence of multiple factors as described in claim 1, characterized in that: In step 5, the rainfall angle is determined based on wind conditions: 0° in windless conditions and 0° in windy conditions. The value is obtained through calculation using a formula; The standard value of wind load perpendicular to the raindrop surface is calculated using the following formula: In the formula: The standard value of wind load is the wind direction perpendicular to the surface of the raindrop; This is the wind pressure height variation coefficient; The projected area of ​​the raindrop subjected to wind pressure; The reference wind pressure standard value; The average diameter of the raindrop; Reference wind pressure standard value The calculation formula is: In the formula: The wind speed is based on a reference height of 10m; The formula for calculating the weight of a raindrop is: In the formula: The weight of the raindrop; It is the acceleration due to gravity; The formula for calculating the weight of a raindrop is: In the formula: The density of raindrops is the same as the density of pure water; The volume of the raindrop; The formula for calculating raindrop volume is: Calculate the angle of rainfall under windy conditions The angle of rainfall in windy conditions is: 。 5. The method for calculating the water catchment of transmission towers considering the influence of multiple factors as described in claim 1, characterized in that: In step 6, considering the non-uniformity of wind direction and speed around the transmission tower, as well as the influence of obstructions on the water catchment of the transmission tower, a calibration factor λ for the water catchment environment of the transmission tower is introduced, with λ ranging from 0.18 to 0.

26.

6. The method for calculating the water catchment of transmission towers considering the influence of multiple factors according to claim 1, characterized in that: In step 7, the water collection volume at the transmission tower location is: 。 7. The method for calculating the water catchment of transmission towers considering the influence of multiple factors as described in claim 1, characterized in that: In step 8, the water catchment monitoring device is used to monitor the test tower location in real time, and the measured water catchment data and rainfall data of the transmission tower during the test are obtained. The obtained raw data are sorted and screened, and the actual data measured by the field test are used for calibration and correction.

8. The method for calculating the water catchment of transmission towers considering the influence of multiple factors as described in claim 1, characterized in that: The water collection monitoring device includes a rain trough (1), which surrounds the four tower feet of the power transmission tower. One side of the rain trough (1) is connected to the measuring water tank (3) through a guide channel (2). A Parshall flume (4) is installed inside the measuring water tank (3). A rigid frame (5) is installed above the Parshall flume (4). An ultrasonic probe (6) is installed on the rigid frame (5). The ultrasonic probe (6) is electrically connected to a flow meter (7).

9. The method for calculating the water catchment of transmission towers considering the influence of multiple factors as described in claim 8, characterized in that: The base platform and bottom of the measuring tank (3) should be kept level.

10. The method for calculating the water catchment of transmission towers considering the influence of multiple factors as described in claim 8, characterized in that: The water flow rate is: In the formula: Q is the flow rate; H is the liquid level height; K and n are constants related to the throat width; The water level height H is: In the formula: D is the distance from the probe to the bottom of the channel; A is the speed of the ultrasonic wave in the air; t is the time difference between the ultrasonic wave transmission and reception; H is the liquid level in the Parshall flume.

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