Test device and method for instability of power transmission tower foundation at river side under extreme load

Abstract

A test apparatus and method for investigating the instability of a power transmission tower foundation located near a river under extreme loads is disclosed. The apparatus comprises a hollow model box with soil and water bodies arranged on its inner bottom wall. The water body is positioned on one side of the soil. The power transmission tower foundation is installed within the soil, and the power transmission tower is connected to the upper side of the foundation. A power transmission line is hinged to the upper side of the tower. Water nozzles are installed on the inner top wall of the model box, and refrigeration and wind power equipment are installed on its side walls. The refrigeration equipment is connected to the power transmission line via copper wires. A potential piping development zone is established within the soil, with one side of the zone connected to the water body. A wave generation system is installed within the water body, positioned relative to the potential piping development zone. The water nozzles, refrigeration equipment, power transmission tower foundation, wind power equipment, and potential piping development zone are connected to a control and monitoring system. This invention not only provides excellent simulation and visualization effects but also achieves high experimental accuracy.

Description

Technical Field

[0001] This invention relates to the field of power transmission tower foundation technology, and in particular to a test device and method for the instability of power transmission tower foundations located near rivers under extreme loads. Background Technology

[0002] With rapid industrialization and urbanization, electricity demand is constantly increasing. In some areas, the power system capacity can no longer meet local needs, and cross-river power transmission projects can provide an effective way to deliver more electricity. When power grid transmission lines cross rivers, the foundations of transmission towers inevitably have to be erected in riverside areas. The stability of these foundations is often affected by hydrological factors, with wave loads being one of the most significant hazards. The impact of waves and the dynamic flow caused by swells erode and wash away the soil around the tower foundation. Long-term erosion and washing can loosen and dissolve the soil, leading to piping, reducing the foundation's bearing capacity, and increasing the risk of instability. Furthermore, waves exert dynamic loads on the tower foundations, causing vibrations and stress concentrations. In severe cases, this can lead to tilting or collapse.

[0003] In addition, transmission towers are often subjected to extreme loads in the natural environment, including wind loads, rain loads, and icing loads. Under extreme loads, transmission towers will bear more horizontal and vertical loads, which will further reduce the stability of the transmission tower foundation.

[0004] Traditional transmission tower foundation design methods do not consider the impact of wave loads and extreme loads on foundation stability, relying solely on empirical formulas and static analysis methods. Therefore, they often cannot accurately predict the instability behavior of transmission tower foundations in riverside areas. Furthermore, there is currently no experimental device that can intuitively demonstrate the instability and failure of transmission tower foundations under wave loads and extreme loads, making it impossible to simulate the actual conditions in riverside areas. Summary of the Invention

[0005] The purpose of this invention is to overcome the defects and problems in the existing technology that cannot accurately simulate the instability behavior of transmission tower foundations in riverside areas, and to provide a test device and method for the instability of transmission tower foundations in riverside locations under extreme loads with good simulation effect.

[0006] To achieve the above objectives, the technical solution of this invention is: a test device for the instability of a transmission tower foundation at a riverside location under extreme loads, comprising a model box, a transmission tower, a transmission tower foundation, a transmission line, and a control and monitoring system. The model box is hollow, and the inner bottom wall of the model box is provided with soil and water. The water is located on one side of the soil. The transmission tower foundation is installed in the soil, and the transmission tower is connected to the upper side of the transmission tower foundation. The transmission line is hinged to the upper side of the transmission tower, and both ends of the transmission line are connected to... Water nozzles are installed on the inner side wall and the inner top wall of the model box. Refrigeration equipment and wind power equipment are installed on the side wall of the model box. The refrigeration equipment is connected to the power transmission line via copper wires. A potential piping development zone is set in the soil. One side of the potential piping development zone is connected to the water body. A wave generation system is set in the water body. The wave generation system is arranged relative to the potential piping development zone. The water nozzles, refrigeration equipment, power transmission tower foundation, wind power equipment, and potential piping development zone are connected to the control and monitoring system.

[0007] The water nozzles are used to generate rainfall and produce rainfall loads;

[0008] The freezing equipment is used to freeze water on the surface of the transmission line into ice and generate an icing load.

[0009] The wind power equipment is used to generate wind and wind load near the power transmission tower;

[0010] The wave generation system is used to generate wave loads in the water body;

[0011] The control and monitoring system is used to adjust the flow rate of water nozzles, adjust the wind intensity in wind power equipment, adjust the freezing intensity of refrigeration equipment, adjust the wave size generated by the wave generation system, monitor the sand output of the potential piping development zone under wave load, and monitor and record the instability state of the transmission tower foundation.

[0012] The control and monitoring system includes a computer, a control unit, an image acquisition device, a stress sensor, a displacement sensor, a vibration sensor, and a tilt sensor. The control unit is connected to a water nozzle, a wind power device, a refrigeration device, and a wave generation system. The computer is connected to the control unit, the image acquisition device, the stress sensor, the displacement sensor, the vibration sensor, and the tilt sensor. The image acquisition device is arranged in the water body and relative to the potential piping development zone. The stress sensor is installed at the bottom of the transmission tower, the displacement sensor is installed on the upper surface of the transmission tower foundation, the vibration sensor is installed on the side surface of the transmission tower foundation, and the tilt sensor is installed at the corner of the transmission tower foundation.

[0013] The image acquisition device is used to observe and acquire the amount of sand produced in the potential development zone of piping under wave load, and send the amount of sand produced to the computer.

[0014] The displacement sensor is used to acquire the settlement value of the transmission tower foundation and send the settlement value to the computer;

[0015] The vibration sensor is used to acquire the vibration frequency and vibration amplitude of the transmission tower foundation and send the vibration frequency and vibration amplitude to the computer.

[0016] The tilt sensor is used to acquire the tilt of the transmission tower foundation and send the tilt to a computer;

[0017] The stress sensor is used to acquire the stress of the transmission tower and send the stress to a computer;

[0018] The control unit is used to adjust the flow rate of the water nozzles, adjust the wind intensity in the wind power equipment, adjust the freezing intensity of the refrigeration equipment, and adjust the wave size of the wave generation system according to the signals sent by the computer.

[0019] The computer is used to analyze the impact of wave load on the development speed of the potential piping development zone based on the sand output; to analyze the impact of the development of the potential piping development zone on the settlement and tilt of the transmission tower foundation; and to analyze the impact of rainfall load, wind load, and icing load on the stress of the transmission tower, as well as the settlement, vibration frequency, vibration amplitude, and tilt of the transmission tower foundation.

[0020] The wind power equipment includes a fan, a shroud, and a wind bag. The side wall of the model box is provided with multiple air vents spaced vertically. The multiple air vents are arranged horizontally. The fan is located outside the model box and is connected to the control and monitoring system. One end of the wind bag is connected to the output end of the fan, and the other end is connected to the outer side wall of the model box and connected to the multiple air vents. The air inlet end of the shroud is connected to the inner side wall of the model box and connected to the multiple air vents. The air outlet end of the shroud is arranged relative to the transmission tower.

[0021] Two telescopic rods are provided between the wind hood and the inner wall of the model box. The two telescopic rods are respectively connected to the control and monitoring system. One end of each telescopic rod is hinged to the inner wall of the model box. The other end of one telescopic rod is connected to the air inlet end of the wind hood near the upper side, and the other end of the other telescopic rod is connected to the air inlet end of the wind hood near the lower side.

[0022] Two wind power devices are provided, and multiple air vents are opened at intervals along the vertical direction on the left and right side walls of the model box. The two wind power devices are symmetrically arranged on the left and right side walls of the model box.

[0023] The wave generation system includes a rotating shaft, a drive mechanism, and multiple push plates. The rotating shaft is horizontally arranged in the water body. One end of the rotating shaft passes through the side wall of the model box and is connected to the drive mechanism. The multiple push plates are circumferentially distributed on the outer circumferential surface of the rotating shaft and are all located in the water body. The drive mechanism is connected to the control and monitoring system.

[0024] A test method for the instability of a transmission tower foundation located near a river under extreme loads, the test method being applied to a test device for the instability of a transmission tower foundation located near a river under extreme loads, the test method comprising the following steps:

[0025] Step 1: Set up three model boxes. Based on the hydrological and geological survey data of the Linjiang area, obtain the surface elevation, soil physical parameters, and relative height data between the river surface and the land surface. Then, according to the similarity principle and similarity ratio, fill the soil and inject water into each model box. Based on the geographical location, climate conditions, ice thickness observation data, and wave buoy observation data of the Linjiang area, obtain the range values ​​of wind load, rainfall load, ice load, and wave load. Then, according to the similarity principle and similarity ratio, determine the range of various load values ​​to be applied in the test of each model box.

[0026] Step 2: Install the transmission tower foundation in the soil, fix the transmission tower to the transmission tower foundation, hinge the transmission line to the transmission tower, install water sprinklers directly above the model box, install wind power equipment and refrigeration equipment on the side wall of the model box, install a wave generation system at the bottom of the water body in the model box, and set a potential piping development zone in the soil.

[0027] Step 3: In the first model box, the water sprinkler system is activated via the control and monitoring system to simulate rainfall, and the flow rate of the water sprinkler system is adjusted to achieve different intensities of rainfall load; the wind turbine system is activated via the control and monitoring system to simulate wind load, and the power of the wind turbine system is adjusted to achieve different intensities of wind load; the refrigeration system is activated via the control and monitoring system to cause water on the surface of the transmission line to freeze into ice, and the power of the refrigeration system is adjusted to achieve different weights of icing load; the instability values ​​of the transmission tower foundation under rainfall load, wind load, and icing load are recorded via the control and monitoring system.

[0028] Step 4: In the second model box, the wave generation system is started by controlling the monitoring system. The wave generation system drives the water body to generate wave load. The monitoring system monitors and records the amount of sand produced per unit time in the potential piping development zone under the wave load. Then, the influence of the development of the potential piping development zone under the wave load on the settlement and tilt of the transmission tower foundation is analyzed.

[0029] Step 5: In the third model box, start the water sprinkler head, wind power equipment, refrigeration equipment, and wave generation system through the control and monitoring system, and adjust the wind load, rain load, icing load, and wave load to the maximum value. Then, record the instability value of the transmission tower foundation under the action of wind load, rain load, icing load, and wave load through the control and monitoring system, determine the dominant instability failure mode of the transmission tower foundation, and determine the instability failure mode of the transmission tower foundation.

[0030] The control and monitoring system includes a computer, a control unit, an image acquisition device, a stress sensor, a displacement sensor, a vibration sensor, and a tilt sensor. The control unit is connected to a water nozzle, a wind power device, a refrigeration device, and a wave generation system. The computer is connected to the control unit, the image acquisition device, the stress sensor, the displacement sensor, the vibration sensor, and the tilt sensor via signals. The image acquisition device is arranged in the water body and relative to the potential piping development zone. The stress sensor is installed at the bottom of the transmission tower, the displacement sensor is installed on the upper surface of the transmission tower foundation, the vibration sensor is installed on the side surface of the transmission tower foundation, and the tilt sensor is installed at the corner of the transmission tower foundation.

[0031] The specific steps in step three of the control and monitoring system for recording the instability values ​​of the transmission tower foundation under rainfall load, wind load, and icing load are as follows: The stress of the transmission tower is recorded using stress sensors. The maximum settlement value Δ1 of the transmission tower foundation is recorded using a displacement sensor; the maximum vibration frequency f1 and maximum vibration amplitude A1 of the transmission tower foundation are recorded using a vibration sensor; and the maximum tilt angle θ1 of the transmission tower foundation is recorded using a tilt sensor.

[0032] Data recorded by stress sensors, displacement sensors, vibration sensors, and tilt sensors are transmitted to a computer. The computer then analyzes the impact of different intensities of rainfall loads, wind loads, and icing loads on the stress of the transmission tower, as well as the foundation settlement, vibration frequency, vibration amplitude, and tilt of the transmission tower.

[0033] The specific steps for the control and monitoring system to monitor and record data in step four are as follows:

[0034] By adjusting different wave heights and frequencies through the control unit, the image acquisition device is activated to monitor and record the amount of sand produced in the potential development zone of piping under wave load. The computer analysis then reveals the impact of wave loads of different intensities on the amount of sand produced per unit time in the potential development zone of piping.

[0035] The control unit keeps the wave load generated by the wave generation system constant, records the change curve of sand output over time under the same intensity wave load, records the change curve of settlement value of transmission tower foundation over time under the same intensity wave load through displacement sensor, and records the change curve of inclination of transmission tower foundation over time through tilt sensor.

[0036] Establish the relationship curves between sand discharge volume and settlement and tilt of transmission tower foundation, and analyze the influence of the development of potential piping development zone on settlement and tilt of transmission tower foundation.

[0037] In step five, the specific steps for the control and monitoring system to record and make judgments are as follows:

[0038] The maximum settlement value Δ2 of the transmission tower foundation 6 is recorded using a displacement sensor; the maximum vibration frequency f2 and maximum vibration amplitude A2 of the transmission tower foundation are recorded using a vibration sensor; the maximum tilt angle θ2 of the transmission tower foundation is recorded using a tilt sensor. Based on the settlement value, vibration frequency, vibration amplitude, and tilt angle recorded in steps three and five, the dominant instability failure mode of the transmission tower foundation is determined.

[0039] when When the value exceeds 0.7, it is determined to be an instability failure dominated by extreme loads. When the value is less than 0.3, it is determined to be wave-load-dominated instability failure. When the value is between 0.3 and 0.7, it is determined to be an instability failure dominated by extreme load coupled with wave load;

[0040] in , , , These are the weighting coefficients, and + + + =1;

[0041] Before the end of the test, if Δ2 / 10cm < θ2 / 0.01, the transmission tower foundation is considered to be in an overturning and unstable failure mode; otherwise, it is considered to be in a sliding and unstable failure mode.

[0042] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0043] 1. The present invention provides a test device and method for the instability of transmission tower foundations in riverside locations under extreme loads. By setting up a model box, refrigeration equipment, water nozzles, wind power equipment, a wave generation system, and a control and monitoring system, it can effectively simulate the effects of wind loads, rain loads, icing loads, and wave loads on the stability of transmission tower foundations. The wave generation system allows for the adjustment of wave intensity and frequency, accurately simulating the impact of wave loads on transmission tower foundations in riverside areas, as well as the development of piping in the soil under long-term wave loads. This provides a relatively realistic reflection of the actual situation in riverside areas and visually reproduces the instability behavior of transmission tower foundations in riverside areas under extreme loads, exhibiting excellent visualization effects. Therefore, the present invention has good simulation and visualization effects.

[0044] 2. In the present invention, a test device and method for the instability of transmission tower foundations located near rivers under extreme loads utilizes multiple different sensors to comprehensively monitor the state of the transmission tower foundation under extreme loads. Simultaneously, the intensity of wind load, rain load, icing load, and wave load is adjusted by a control unit to observe and analyze the impact of different loads on the transmission tower foundation. By comprehensively considering four indicators—settlement, vibration frequency, vibration amplitude, and tilt—different dominant instability failure modes of the transmission tower foundation are determined, thereby revealing the dominant causes of instability and facilitating subsequent design and prevention of transmission tower foundation instability. Therefore, the present invention exhibits high experimental accuracy and good simulation results.

[0045] 3. In the present invention, a test device and method for the instability of a transmission tower foundation located near a river under extreme loads is provided. Wind direction is adjusted by setting up telescopic rods, and unidirectional wind and cyclone simulations are achieved by setting up two sets of fans. Rotating the shaft drives the push plates to rotate on the shaft, and the rotation of multiple push plates simulates the effect of waves. Therefore, the present invention has high test accuracy and good simulation effect.

[0046] 4. In the present invention, a test device and method for the instability of transmission tower foundations located near rivers under extreme loads is used. Three model boxes are employed to obtain different data through comparative experiments. The values ​​of wind load, rain load, icing load, and wave load under extreme conditions are recorded in the third model box. This allows for the determination of the dominant instability failure mode of the transmission tower foundation and the identification of its instability failure pattern. This information is then used in subsequent construction engineering design to identify the causes of foundation instability and to implement corresponding protective and reinforcing structures, thereby improving the stability of the transmission tower foundation. Therefore, this invention has high reliability and good simulation results. Attached Figure Description

[0047] Figure 1 This is a schematic diagram of the structure of the test device for the instability of the foundation of a power transmission tower located near the river under extreme loads in this invention.

[0048] Figure 2 yes Figure 1 Enlarged diagram of point A in the middle.

[0049] Figure 3 yes Figure 1 Enlarged diagram of point B in the middle.

[0050] Figure 4 yes Figure 1 Enlarged diagram of point C in the middle.

[0051] Figure 5 This is a connection diagram of the control and monitoring system in this invention.

[0052] Figure 6 This is a connection diagram of the control unit in this invention.

[0053] In the diagram: Model box 1, Control and monitoring system 2, Computer 21, Control unit 22, Image acquisition device 23, Stress sensor 24, Displacement sensor 25, Vibration sensor 26, Tilt sensor 27, Wind power equipment 3, Fan 31, Wind bag 32, Wind cover 33, Telescopic pole 34, Wave generation system 4, Rotating shaft 41, Push plate 42, Drive mechanism 43, Transmission tower 5, Transmission tower foundation 6, Transmission line 7, Soil 8, Potential piping development zone 81, Water body 9, Water nozzle 10, Refrigeration equipment 11, Copper conductor 12, Air outlet 13. Detailed Implementation

[0054] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0055] Example 1:

[0056] See Figures 1 to 6A test device for the instability of a transmission tower foundation located near a river under extreme loads includes a model box 1, a transmission tower 5, a transmission tower foundation 6, a transmission line 7, and a control and monitoring system 2. The model box 1 is hollow inside. Soil 8 and water 9 are arranged on the inner bottom wall of the model box 1. The water 9 is located on one side of the soil 8. The transmission tower foundation 6 is installed in the soil 8. The transmission tower 5 is connected to the upper side of the transmission tower foundation 6. The transmission line 7 is hinged to the upper side of the transmission tower 5. Both ends of the transmission line 7 are connected to the inner side wall of the model box 1. A water spray head 1 is installed on the inner top wall of the model box 1. 0. The side wall of the model box 1 is equipped with a refrigeration device 11 and a wind power device 3. The refrigeration device 11 is connected to the power transmission line 7 through a copper wire 12. A piping potential development zone 81 is set in the soil 8. The piping potential development zone 8 is composed of coarse sand particles with a diameter of 2mm. One side of the piping potential development zone 81 is connected to the water body 9. A wave generation system 4 is set in the water body 9. The wave generation system 4 is arranged relative to the piping potential development zone 81. The water nozzle 10, the refrigeration device 11, the power transmission tower foundation 6, the wind power device 3, the piping potential development zone 81 are connected to the control and monitoring system 2.

[0057] The water nozzle 10 is used to generate rainfall and produce rainfall load;

[0058] The freezing device 11 is used to freeze water on the surface of the power transmission line 7 into ice and generate an ice load.

[0059] The wind power device 3 is used to generate wind and wind load near the transmission tower 5;

[0060] The wave generation system 4 is used to drive the water body 9 to generate wave loads;

[0061] The control and monitoring system 2 is used to adjust the flow rate of the water nozzle 10, adjust the wind intensity in the wind power equipment 3, adjust the freezing intensity of the refrigeration equipment 11, adjust the wave size generated by the wave generation system 4, monitor the amount of sand produced in the potential piping development zone 81 under wave load, and monitor and record the instability state of the transmission tower foundation 6.

[0062] The control and monitoring system 2 includes a computer 21, a control unit 22, an image acquisition device 23, a stress sensor 24, a displacement sensor 25, a vibration sensor 26, and a tilt sensor 27. The control unit 22 is connected to the water nozzle 10, the wind power equipment 3, the refrigeration equipment 11, and the wave generation system 4. The computer 21 is connected to the control unit 22, the image acquisition device 23, the stress sensor 24, the displacement sensor 25, the vibration sensor 26, and the tilt sensor 27. The image acquisition device 23 is arranged in the water body 9 and relative to the potential piping development zone 81. The stress sensor 24 is installed at the bottom of the transmission tower 5. The displacement sensor 25 is installed on the upper surface of the transmission tower foundation 6. The vibration sensor 26 is installed on the side surface of the transmission tower foundation 6. The tilt sensor 27 is installed at the corner of the transmission tower foundation 6.

[0063] The image acquisition device 23 is used to observe and acquire the amount of sand produced in the potential development zone 81 of piping under wave load, and send the amount of sand produced to the computer 21.

[0064] The displacement sensor 25 is used to acquire the settlement value of the transmission tower foundation 6 and send the settlement value to the computer 21;

[0065] The vibration sensor 26 is used to acquire the vibration frequency and vibration amplitude of the transmission tower foundation 6, and send the vibration frequency and vibration amplitude to the computer 21;

[0066] The tilt sensor 27 is used to obtain the tilt of the transmission tower foundation 6 and send the tilt to the computer 21.

[0067] The stress sensor 24 is used to acquire the stress of the transmission tower 5 and send the stress to the computer 21;

[0068] The control unit 22 is used to adjust the flow rate of the water nozzle 10, adjust the wind intensity in the wind power device 3, adjust the freezing intensity of the refrigeration device 11, and adjust the wave size of the wave generation system 4 according to the signals sent by the computer 21.

[0069] The computer 21 is used to analyze the impact of wave load on the development speed of the potential piping development zone 81 based on the amount of sand produced; to analyze the impact of the development of the potential piping development zone 81 on the settlement and tilt of the transmission tower foundation 6; and to analyze the impact of rainfall load, wind load, and icing load on the stress of the transmission tower 5 and the settlement, vibration frequency, vibration amplitude, and tilt of the transmission tower foundation 6.

[0070] A test method for the instability of a transmission tower foundation located near a river under extreme loads, the test method being applied to a test device for the instability of a transmission tower foundation located near a river under extreme loads, the test method comprising the following steps:

[0071] Step 1: Set up three model boxes 1. Based on the hydrological and geological survey data of the Linjiang area, obtain the surface elevation, soil physical parameters, and relative height data between the river surface and the land surface. Then, according to the similarity principle and similarity ratio, fill the soil 8 and inject water into each model box 1. Based on the geographical location, climate conditions, ice thickness observation data, and wave buoy observation data of the Linjiang area, obtain the range values ​​of wind load, rainfall load, ice load, and wave load. Then, according to the similarity principle and similarity ratio, determine the range of various load values ​​to be applied in the test of each model box 1.

[0072] Step 2: Install the transmission tower foundation 6 in the soil 8, fix the transmission tower 5 to the transmission tower foundation 6, hinge the transmission line 7 to the transmission tower 5, install the water nozzle 10 directly above the model box 1, install the wind power equipment 3 and the refrigeration equipment 11 on the side wall of the model box 1, install the wave generation system 4 at the bottom of the water body 9 in the model box 1, and set the potential piping development zone 81 in the soil 8;

[0073] Step 3: In the first model box 1, the water sprinkler head 10 is activated by the control and monitoring system 2 to simulate rainfall. Different intensities of rainfall load are achieved by adjusting the flow rate of the water sprinkler head 10. The wind power equipment 3 is activated by the control and monitoring system 2 to simulate wind load. Different intensities of wind load are achieved by adjusting the power of the wind power equipment 3. The freezing equipment 11 is activated by the control and monitoring system 2 to cause the water on the surface of the transmission line 7 to freeze into ice. Different weights of icing load are achieved by adjusting the power of the freezing equipment 11. The stress of the transmission tower is recorded by the stress sensor 24. The maximum settlement value Δ1 of the transmission tower foundation 6 is recorded by displacement sensor 25; the maximum vibration frequency f1 and maximum vibration amplitude A1 of the transmission tower foundation 6 are recorded by vibration sensor 26; and the maximum tilt angle θ1 of the transmission tower foundation 6 is recorded by tilt sensor 27.

[0074] The data recorded by stress sensor 24, displacement sensor 25, vibration sensor 26, and tilt sensor 27 are transmitted to computer 21. Computer 21 analyzes the influence of different intensities of rainfall load, different intensities of wind load, and different weights of icing load on the stress of transmission tower 5, as well as the settlement value, vibration frequency, vibration amplitude, and tilt of transmission tower foundation 6.

[0075] Step 4: In the second model box 1, the wave generation system 4 is started by the control and monitoring system 2. The wave generation system 4 drives the water body 9 to generate wave load. The control unit 22 adjusts different wave heights and wave frequencies, and the image acquisition device 23 is turned on to monitor and record the amount of sand produced in the potential piping development zone 81 under the action of wave load. The computer 21 analyzes the effect of wave loads of different intensities on the amount of sand produced in the potential piping development zone 81 per unit time.

[0076] The control unit 22 keeps the wave load generated by the wave generation system 4 constant, records the change curve of the sand output over time under the same intensity wave load, and records the change curve of the sand output over time under the same intensity wave load through the displacement sensor 25, and records the change curve of the settlement value of the transmission tower foundation 6 over time under the same intensity wave load through the tilt sensor 27.

[0077] Establish the relationship curve between sand discharge and settlement and tilt of transmission tower foundation 6, and analyze the influence of the development of the potential piping development zone 81 on the settlement and tilt of transmission tower foundation 6.

[0078] Step 5: In the third model box 1, start the water nozzle 10, wind power equipment 3, refrigeration equipment 11, and wave generation system 4 through the control and monitoring system 2, and adjust the wind load, rainfall load, icing load, and wave load to their maximum values. Stop the test when one of the following conditions is met, and the transmission tower foundation 6 is determined to be in an unstable state: the value monitored by the tilt sensor 27 reaches 1% or the value monitored by the displacement sensor 25 reaches 10cm; the maximum settlement value Δ2 of the transmission tower foundation 6 is recorded by the displacement sensor 25; the maximum vibration frequency f2 and the maximum vibration amplitude A2 of the transmission tower foundation are recorded by the vibration sensor 26; the maximum tilt angle θ2 of the transmission tower foundation 6 is recorded by the tilt sensor 27. Based on the settlement value, vibration frequency, vibration amplitude, and tilt angle in Step 3 and Step 5, determine the dominant instability failure mode of the transmission tower foundation 6:

[0079] when When the value exceeds 0.7, it is determined to be an instability failure dominated by extreme loads. When the value is less than 0.3, it is determined to be wave-load-dominated instability failure. When the value is between 0.3 and 0.7, it is determined to be an instability failure dominated by extreme load coupled with wave load;

[0080] in , , , These are the weighting coefficients, and + + + =1;

[0081] Before the end of the test, if Δ2 / 10cm < θ2 / 0.01, the transmission tower foundation is considered to be in an overturning and unstable failure mode; otherwise, it is considered to be in a sliding and unstable failure mode.

[0082] Example 2:

[0083] The basic content is the same as in Example 1, except that:

[0084] See Figures 1 to 3 The wind power equipment 3 includes a fan 31, a wind cover 33, and a wind bag 32. The side wall of the model box 1 is provided with multiple air vents 13 spaced apart in the vertical direction. The multiple air vents 13 are arranged horizontally. The fan 31 is located outside the model box 1 and is connected to the control and monitoring system 2. One end of the wind bag 32 is connected to the output end of the fan 31, and the other end is connected to the outer side wall of the model box 1 and connected to the multiple air vents 13. The air inlet end of the wind cover 33 is connected to the inner bottom wall of the model box 1 and connected to the multiple air vents 13. The air outlet end of the wind cover 33 is arranged relative to the transmission tower 5. Two telescopic rods 34 are provided between the wind cover 33 and the inner wall of the model box 1. The two telescopic rods 34 are respectively connected to the control and monitoring system 2. One end of each telescopic rod 34 is hinged to the inner wall of the model box 1. The other end of one telescopic rod 34 is connected to the upper air inlet of the wind cover 33, and the other end of the other telescopic rod 34 is connected to the lower air inlet of the wind cover 33. Two wind power devices 3 are provided. Multiple air vents 13 are opened at intervals along the vertical direction on the left and right side walls of the model box 1. The two wind power devices 3 are symmetrically arranged on the left and right side walls of the model box 1.

[0085] Example 3:

[0086] See Figure 4 and Figure 5 The wave generation system 4 includes a rotating shaft 41, a driving mechanism 43, and multiple push plates 42. The rotating shaft 41 is horizontally arranged in the water body 9. One end of the rotating shaft 41 passes through the side wall of the model box 1 and is connected to the driving mechanism 43. The multiple push plates 42 are circumferentially distributed on the outer circumferential surface of the rotating shaft 41 and are all located in the water body 9. The driving mechanism 43 is connected to the control and monitoring system 2.

Claims

1. A test device for the instability of transmission tower foundations located near a river under extreme loads, characterized in that: The system includes a model box (1), a transmission tower (5), a transmission tower foundation (6), a transmission line (7), and a control and monitoring system (2). The model box (1) is hollow inside. The bottom wall of the model box (1) is provided with soil (8) and water (9). The water (9) is located on one side of the soil (8). The transmission tower foundation (6) is installed in the soil (8). The transmission tower (5) is connected to the upper side of the transmission tower foundation (6). The transmission line (7) is hinged to the upper side of the transmission tower (5). The two ends of the transmission line (7) are connected to the inner wall of the model box (1). A water spray nozzle (10) is installed on the inner top wall of the model box (1). The model box (1) is equipped with a refrigeration device (11) and a wind power device (3) on its side wall. The refrigeration device (11) is connected to the power transmission line (7) through a copper wire (12). A potential piping development zone (81) is set in the soil (8). One side of the potential piping development zone (81) is connected to the water body (9). A wave generation system (4) is set in the water body (9). The wave generation system (4) is arranged relative to the potential piping development zone (81). The water nozzle (10), the refrigeration device (11), the power transmission tower foundation (6), the wind power device (3), the potential piping development zone (81) are connected to the control and monitoring system (2). The water nozzle (10) is used to generate rainfall and produce rainfall load; The freezing equipment (11) is used to condense water on the surface of the transmission line (7) into ice and generate an ice load; The wind power equipment (3) is used to generate wind and generate wind load near the transmission tower (5); The wave generation system (4) is used to drive the water body (9) to generate wave loads; The control and monitoring system (2) is used to adjust the flow rate of the water nozzle (10), adjust the wind intensity in the wind power equipment (3), adjust the freezing intensity of the refrigeration equipment (11), adjust the wave size generated by the wave generation system (4), monitor the sand output of the potential development zone (81) under wave load, and monitor and record the instability state of the transmission tower foundation (6).

2. The test device for the instability of a transmission tower foundation at a riverside location under extreme loads as described in claim 1, characterized in that: The control and monitoring system (2) includes a computer (21), a control unit (22), an image acquisition device (23), a stress sensor (24), a displacement sensor (25), a vibration sensor (26), and a tilt sensor (27). The control unit (22) is connected to the water nozzle (10), the wind power equipment (3), the refrigeration equipment (11), and the wave generation system (4), respectively. The computer (21) is connected to the control unit (22), the image acquisition device (23), the stress sensor (24), and the displacement sensor (25), respectively. The vibration sensor (26) and the tilt sensor (27) are connected together. The image acquisition device (23) is arranged in the water body (9) and relative to the potential development zone (81) of piping. The stress sensor (24) is installed at the bottom of the transmission tower (5). The displacement sensor (25) is installed on the upper surface of the transmission tower foundation (6). The vibration sensor (26) is installed on the side surface of the transmission tower foundation (6). The tilt sensor (27) is installed at the corner of the transmission tower foundation (6). The image acquisition device (23) is used to observe and acquire the amount of sand produced in the potential development zone (81) of piping under wave load, and send the amount of sand produced to the computer (21); The displacement sensor (25) is used to acquire the settlement value of the transmission tower foundation (6) and send the settlement value to the computer (21); The vibration sensor (26) is used to acquire the vibration frequency and vibration amplitude of the transmission tower foundation (6) and send the vibration frequency and vibration amplitude to the computer (21); The tilt sensor (27) is used to obtain the tilt of the transmission tower foundation (6) and send the tilt to the computer (21); The stress sensor (24) is used to acquire the stress of the transmission tower (5) and send the stress to the computer (21); The control unit (22) is used to adjust the flow rate of the water nozzle (10), adjust the wind intensity in the wind power device (3), adjust the freezing intensity of the refrigeration device (11), and adjust the wave size of the wave generation system (4) according to the signal sent by the computer (21). The computer (21) is used to analyze the impact of wave load on the development speed of the potential development zone (81) of piping based on the amount of sand produced; to analyze the degree of influence of the development of the potential development zone (81) of piping on the settlement and tilt of the transmission tower foundation (6); and to analyze the degree of influence of rainfall load, wind load, and icing load on the stress of the transmission tower (5) and the settlement, vibration frequency, vibration amplitude and tilt of the transmission tower foundation (6).

3. The test device for the instability of a transmission tower foundation at a riverside location under extreme loads as described in claim 1, characterized in that: The wind power equipment (3) includes a fan (31), a wind cover (33), and a wind bag (32). The side wall of the model box (1) is provided with multiple air outlets (13) spaced apart in the vertical direction. The multiple air outlets (13) are arranged horizontally. The fan (31) is located outside the model box (1) and is connected to the control and monitoring system (2). One end of the wind bag (32) is connected to the output end of the fan (31), and the other end is connected to the outer side wall of the model box (1) and connected to the multiple air outlets (13). The air inlet end of the wind cover (33) is connected to the inner side wall of the model box (1) and connected to the multiple air outlets (13). The air outlet end of the wind cover (33) is arranged relative to the power transmission tower (5).

4. The test device for the instability of a transmission tower foundation at a riverside location under extreme loads as described in claim 3, characterized in that: Two telescopic rods (34) are provided between the wind cover (33) and the inner wall of the model box (1). The two telescopic rods (34) are respectively connected to the control and monitoring system (2). One end of the two telescopic rods (34) is respectively hinged to the inner wall of the model box (1). The other end of one telescopic rod (34) is connected to the air inlet end of the wind cover (33) near the upper side, and the other end of the other telescopic rod (34) is connected to the air inlet end of the wind cover (33) near the lower side.

5. The test device for the instability of a transmission tower foundation at a riverside location under extreme loads as described in claim 3, characterized in that: Two wind power devices (3) are provided. Multiple air vents (13) are opened at intervals along the vertical direction on the left and right side walls of the model box (1). The two wind power devices (3) are symmetrically arranged on the left and right side walls of the model box (1).

6. The test device for the instability of a transmission tower foundation at a riverside location under extreme loads as described in claim 1, characterized in that: The wave generation system (4) includes a rotating shaft (41), a driving mechanism (43), and multiple push plates (42). The rotating shaft (41) is horizontally arranged in the water body (9). One end of the rotating shaft (41) passes through the side wall of the model box (1) and is connected to the driving mechanism (43). The multiple push plates (42) are circumferentially distributed on the outer circumferential surface of the rotating shaft (41) and are all located in the water body (9). The driving mechanism (43) is connected to the control and monitoring system (2).

7. A test method for the instability of transmission tower foundations located near a river under extreme loads, characterized in that: The test method is applied to the test device for the instability test of a transmission tower foundation located near a river under extreme loads as described in claim 1. The test method includes the following steps: Step 1: Set up three model boxes (1). Based on the hydrological and geological survey data of the Linjiang area, obtain the surface elevation, soil physical parameters, and relative height data between the river surface and the ground surface. Then, according to the similarity principle and similarity ratio, fill the soil (8) and inject water in each model box (1). Based on the geographical location, climate conditions, ice thickness observation data, and wave buoy observation data of the Linjiang area, obtain the range values ​​of wind load, rainfall load, ice load, and wave load. Then, according to the similarity principle and similarity ratio, determine the range of various load values ​​to be applied in the test of each model box (1). Step 2: Install the transmission tower foundation (6) in the soil (8), fix the transmission tower (5) to the transmission tower foundation (6), hinge the transmission line (7) to the transmission tower (5), install water nozzles (10) directly above the model box (1), install wind power equipment (3) and refrigeration equipment (11) on the side wall of the model box (1), install wave generation system (4) at the bottom of the water body (9) in the model box (1), and set up a potential piping development zone (81) in the soil (8); Step 3: In the first model box (1), the water nozzle (10) is started by the control and monitoring system (2) to simulate rainfall. Different intensities of rainfall load are achieved by adjusting the flow rate of the water nozzle (10); the wind power equipment (3) is started by the control and monitoring system (2) to simulate wind load. Different intensities of wind load are achieved by adjusting the power of the wind power equipment (3); the freezing equipment (11) is started by the control and monitoring system (2) to cause the water on the surface of the transmission line (7) to freeze into ice. Different weights of ice load are achieved by adjusting the power of the freezing equipment (11); the instability value of the transmission tower foundation (6) under rainfall load, wind load, and ice load is recorded by the control and monitoring system (2). Step 4: In the second model box (1), the wave generation system (4) is started by the control and monitoring system (2). The wave generation system (4) drives the water body (9) to generate wave load. The control and monitoring system (2) monitors and records the amount of sand produced per unit time in the potential development zone (81) of piping under the action of wave load. Then, the influence law of the development of the potential development zone (81) of piping under the action of wave load on the settlement value and tilt of the transmission tower foundation (6) is analyzed. Step 5: In the third model box (1), start the water nozzle (10), wind power equipment (3), refrigeration equipment (11), and wave generation system (4) through the control and monitoring system (2), and adjust the wind load, rain load, icing load, and wave load to the maximum value. Then, record the instability value of the transmission tower foundation (6) under the action of wind load, rain load, icing load, and wave load through the control and monitoring system (2), determine the dominant instability failure mode of the transmission tower foundation (6), and determine the instability failure mode of the transmission tower foundation (6).

8. The method for testing the instability of a transmission tower foundation at a riverside location under extreme loads as described in claim 7, characterized in that: The control and monitoring system (2) includes a computer (21), a control unit (22), an image acquisition device (23), a stress sensor (24), a displacement sensor (25), a vibration sensor (26), and a tilt sensor (27). The control unit (22) is connected to a water nozzle (10), a wind power device (3), a refrigeration device (11), and a wave generation system (4). The computer (21) communicates with the control unit (22), the image acquisition device (23), the stress sensor (24), and the displacement sensor (25) via signals. 25) Vibration sensor (26) and tilt sensor (27) are connected. The image acquisition device (23) is arranged in the water body (9) and relative to the potential development zone (81) of piping. The stress sensor (24) is installed at the bottom of the transmission tower (5). The displacement sensor (25) is installed on the upper surface of the transmission tower foundation (6). The vibration sensor (26) is installed on the side surface of the transmission tower foundation (6). The tilt sensor (27) is installed at the corner of the transmission tower foundation (6). The specific steps for the control and monitoring system (2) in step three to record the instability values ​​of the transmission tower foundation (6) under rainfall load, wind load, and icing load are as follows: the stress of the transmission tower is recorded by the stress sensor (24). The maximum settlement value Δ1 of the transmission tower foundation (6) was recorded by displacement sensor (25); the maximum vibration frequency f1 and maximum vibration amplitude A1 of the transmission tower foundation (6) were recorded by vibration sensor (26); and the maximum tilt θ1 of the transmission tower foundation (6) was recorded by tilt sensor (27). The data recorded by the stress sensor (24), displacement sensor (25), vibration sensor (26), and tilt sensor (27) are transmitted to the computer (21). The computer (21) analyzes the influence of different intensities of rainfall load, different intensities of wind load, and different weights of icing load on the stress of the transmission tower (5) and the settlement, vibration frequency, vibration amplitude, and tilt of the transmission tower foundation (6).

9. The method for testing the instability of a transmission tower foundation at a riverside location under extreme loads as described in claim 8, characterized in that: The specific steps for the control and monitoring system (2) to monitor and record in step four are as follows: By adjusting different wave heights and wave frequencies through the control unit (22), the image acquisition device (23) is turned on to monitor and record the amount of sand produced in the potential development zone (81) of piping under wave load. The computer (21) analyzes the effect of wave loads of different intensities on the amount of sand produced in the potential development zone (81) of piping per unit time. The wave load generated by the wave generation system (4) is kept constant by the control unit (22), and the change curve of the sand output under the same intensity wave load is recorded. At the same time, the settlement value of the transmission tower foundation (6) under the same intensity wave load is recorded by the displacement sensor (25), and the inclination of the transmission tower foundation (6) under the same intensity wave load is recorded by the tilt sensor (27). Establish the relationship curve between the amount of sand produced and the settlement and inclination of the transmission tower foundation (6), and analyze the influence of the development of the potential development zone (81) of piping on the settlement and inclination of the transmission tower foundation (6).

10. The method for testing the instability of a transmission tower foundation at a riverside location under extreme loads as described in claim 8, characterized in that: In step five, the specific steps for the control and monitoring system (2) to record and judge are as follows: The maximum settlement value Δ2 of the transmission tower foundation (6) is recorded by displacement sensor (25); the maximum vibration frequency f2 and maximum vibration amplitude A2 of the transmission tower foundation are recorded by vibration sensor (26); the maximum tilt angle θ2 of the transmission tower foundation (6) is recorded by tilt sensor (27). Based on the settlement value, vibration frequency, vibration amplitude and tilt angle in steps three and five, the dominant instability failure mode of the transmission tower foundation (6) is determined: when When the value exceeds 0.7, it is determined to be an instability failure dominated by extreme loads. When the value is less than 0.3, it is determined to be wave-load-dominated instability failure. When the value is between 0.3 and 0.7, it is determined to be an instability failure dominated by extreme load coupled with wave load; in , , , These are the weighting coefficients, and + + + =1; Before the end of the test, if Δ2 / 10cm < θ2 / 0.01, the transmission tower foundation is considered to be in an overturning and unstable failure mode; otherwise, it is considered to be in a sliding and unstable failure mode.

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