A power transmission tower omnidirectional avalanche impact simulation test system and method

Abstract

The present application relates to the field of geological disaster prevention and engineering structure safety evaluation, and discloses a kind of power transmission tower omnidirectional avalanche impact simulation test system and method, the system includes variable gradient avalanche slide bed, embedded omnidirectional rotary test assembly, flexible bridging seal and multi-source heterogeneous stability monitoring unit.Rotary test assembly is installed in the mounting hole of horizontal test section bottom plate, load cover is flush with bottom plate, flexible seal is crossed between mounting hole and cover plate to realize coplanar, the method includes empty load parasitic stiffness calibration, omnidirectional step impact scanning, load decoupling and space-time alignment, comprehensive stability index and tangent stiffness degradation dual discrimination, generate omnidirectional stability radar map, the present application breaks through the blind area limit of discretization fixed angle test, and overcomes the misjudgment risk of single strength index to geometric nonlinear instability through multi-source data fusion.

Description

Technical Field

[0001] This invention relates to the field of geological disaster prevention and engineering structure safety assessment technology, and in particular to a test system and stability assessment method for simulating the multi-angle impact of avalanche particles and fluids on a transmission tower and assessing its omnidirectional instability characteristics. Background Technology

[0002] With the deepening of the national energy strategy, the traversal of ultra-high-voltage transmission lines through steep terrain and harsh climates in high-altitude mountainous areas has become an inevitable trend. In these regions, avalanches are frequent geological disasters, posing a significant threat to transmission towers crossing valleys. As a tall, lattice-structured steel structure, the mechanical properties of transmission towers exhibit significant anisotropy. Unlike cylindrical bridge piers, the projected area, stiffness distribution, and node connection forms of transmission towers differ in the front, side, and diagonal directions. This means that the same amount of avalanche fluid impacting the tower at different angles will produce vastly different base shear forces, overturning moments, and torsional effects. Therefore, accurately assessing the impact response of transmission towers at all angles to prevent catastrophic collapse is a crucial aspect of engineering design.

[0003] Currently, physical model testing is the core method for studying such problems. Simulating an avalanche by releasing granular fluid into a sloped chute, impacting a scaled-down tower model, and measuring the forces involved is the primary basis for obtaining design parameters. However, existing avalanche physical simulation testing techniques still face significant technical bottlenecks in the following three aspects:

[0004] First, discretized fixed-angle testing leads to blind spots in operational conditions. Currently, most testing devices use fixed installation methods, testing only typical angles such as the front or side. The industry generally believes that the impact load directly facing the flow direction is the largest, and therefore the most dangerous condition. However, transmission towers are highly statically indeterminate structures, and their failure modes are controlled by the stability of the compression members. Under frontal impact, the load is usually shared by the two tower legs on the back side, and the structure experiences symmetrical stress with almost no torsional effect, making the structure less prone to failure. However, at certain asymmetric critical orientations, the load easily concentrates on a single tower leg, causing a sharp increase in axial pressure on that leg; simultaneously, the additional torque generated by the asymmetric flow introduces additional shear stress. This coupling effect of axial pressure and torque can easily lead to premature local buckling or overall instability of the tower before the total base shear force reaches its peak. Existing discretized testing methods are inefficient, and more importantly, it is difficult to conduct high-density angular impact tests, easily missing the most dangerous conditions of transmission towers at specific asymmetric angles.

[0005] Secondly, the rotating device causes boundary layer interference and seal failure in the dense flow field of the avalanche bottom layer. Avalanche fluid is a gravity-driven dense particle flow, which exhibits significant stratification during its movement. The dense layer close to the slide surface at the bottom layer has high density and high momentum flux. To achieve variable angle testing, some experimental devices attempt to install the industrial rotary table directly onto the slide bottom plate. However, it is difficult to keep its surface perfectly flush with the slide bottom plate, and there are usually small steps or installation gaps. In high-speed particle flow, even a step protrusion of a few millimeters can produce particle projection effects, while gaps and depressions can induce local cavity vortices, causing boundary layer separation of the avalanche fluid at the bottom of the model, resulting in severe distortion of the monitored base shear force and overturning moment. In addition, fine particles are very likely to get stuck in the gap between the turntable and the slide, causing a sharp increase in the frictional resistance of the rotating mechanism, resulting in an abnormally high motor load, failure to rotate accurately according to the predetermined command, or even mechanical jamming.

[0006] Third, structural criteria based on a single base load have failure problems. Existing experimental systems typically rely solely on force sensors at the bottom to record base reactions. However, transmission towers are highly statically indeterminate flexible structures that exhibit strong geometric nonlinearity under avalanche impacts. Their failure often begins with buckling of local compression members, leading to a sudden change in the overall structural stiffness. Relying solely on the magnitude of the base force cannot identify this stiffness degradation, i.e., the tower body has undergone irreversible large deformation or torsion, but the base force has not yet reached its peak value. Due to the lack of simultaneous monitoring of multi-dimensional response indicators such as the tower top displacement field and the strain of key members, experiments cannot construct a comprehensive instability criterion based on load-displacement-strain, making it highly susceptible to misjudging dynamic instability conditions as safe.

[0007] In summary, there is an urgent need to develop a dedicated testing device and method that integrates zero-disturbance embedded load-bearing, flexible sealing error correction, and multi-source heterogeneous stability monitoring. Summary of the Invention

[0008] To address the aforementioned technical problems, this invention provides a system and method for simulating omnidirectional avalanche impact on transmission towers.

[0009] The omnidirectional avalanche impact simulation test system for transmission towers provided by this invention includes a variable-slope avalanche slide, an embedded omnidirectional rotation test assembly, a flexible bridging seal, and a multi-source heterogeneous stability monitoring unit. The variable-slope avalanche slide includes an acceleration slide section, a flow control section, and a horizontal test section connected in sequence. An embedded mounting countersunk hole is formed on the bottom plate of the horizontal test section. The embedded omnidirectional rotation test assembly is installed within the embedded mounting countersunk hole and includes a bearing cover plate, a six-dimensional force sensor, and an indexing drive mechanism connected in series from top to bottom. The top surface of the bearing cover plate is flush with the upper surface of the bottom plate of the horizontal test section. The flexible bridging seal is an annular flexible film that spans between the wall of the embedded mounting countersunk hole and the outer edge of the bearing cover plate. Its upper surface is coplanar with the upper surface of the bottom plate and the top surface of the bearing cover plate. The multi-source heterogeneous stability monitoring unit includes a six-dimensional force sensor, a non-contact displacement tracking subsystem, and a local strain acquisition subsystem. The three subsystems achieve time-synchronized acquisition through a synchronous trigger controller.

[0010] Specifically, the upper edge of the recessed mounting hole is machined with an annular stationary countersunk platform, and the upper edge of the outer edge of the bearing cover is machined with an annular moving countersunk platform. The outer ring of the flexible bridging seal is embedded in the stationary countersunk platform, and the inner ring is embedded in the moving countersunk platform. The thickness of the flexible bridging seal matches the depth of the stationary countersunk platform and the moving countersunk platform.

[0011] Specifically, the flexible bridging seal is a silicone rubber film, with a polytetrafluoroethylene wear-resistant coating on the side facing the flow field. The height deviation between the top surface of the bearing cover, the upper surface of the flexible bridging seal, and the upper surface of the bottom plate of the horizontal test section is controlled within ±0.1mm.

[0012] Specifically, an embedded fine-tuning mechanism is provided between the bearing cover plate and the six-dimensional force sensor. The embedded fine-tuning mechanism includes multiple sets of precision adjustment pillars evenly distributed to perform micron-level compensation on the vertical height of the bearing cover plate.

[0013] Specifically, the indexing drive mechanism includes a servo drive motor and a reducer, the reducer providing a self-locking holding torque for rigidly locking the bearing cover plate during avalanche fluid impact.

[0014] Specifically, the inclination angle of the acceleration slide section is greater than the internal friction angle of the simulated avalanche material, the flow control section achieves stepless adjustment of the slope through a hydraulic drive mechanism, and arc-shaped transition plates are provided between the acceleration slide section and the flow control section, as well as between the flow control section and the horizontal test section.

[0015] This invention also provides a method for assessing the omnidirectional avalanche impact stability of transmission towers, comprising four steps: no-load calibration and parasitic stiffness modeling, omnidirectional automated step-impact scanning, load decoupling and spatiotemporal alignment of multidimensional data, and quantitative calculation and critical orientation identification of comprehensive stability criteria. By constructing a parasitic stiffness characteristic curve function to dynamically subtract system errors introduced by the sealing components, the comprehensive stability evaluation index is calculated by integrating three-dimensional data of base load, tower top displacement, and main material strain, and a dual discrimination is performed using the tangential stiffness degradation criterion, ultimately generating an omnidirectional stability radar map.

[0016] The beneficial effects of this invention are as follows: First, by achieving omnidirectional step-scan through the embedded omnidirectional rotating test assembly, it overcomes the blind zone limitation of traditional discrete fixed-angle testing, enabling high-resolution traversal of all potential critical instability locations on the transmission tower and accurately capturing anisotropic instability conditions caused by the coupling of high axial pressure on the tower legs and additional fluid torque. Second, through the coplanar design of the double-platform of the flexible bridging seal, it ensures the absolute continuity of the bottom boundary of the horizontal test section while achieving physical isolation of fine particles. Combined with the parasitic stiffness decoupling algorithm to eliminate sealing damping interference, it achieves the unity of realistic flow field construction and high-precision force measurement. Third, through the comprehensive stability evaluation index of multi-source heterogeneous data fusion and tangential stiffness singularity point discrimination, it overcomes the risk of misjudging geometric nonlinear instability by a single strength index, and can identify instability conditions where irreversible large geometric deformation has occurred in advance before the base load reaches its peak. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the overall structure of the system of the present invention.

[0018] Figure 2 This is a cross-sectional view of the embedded omnidirectional rotation test assembly of the present invention.

[0019] Figure 3 This is a schematic diagram of the multi-source heterogeneous monitoring layout of the present invention.

[0020] Figure 4 This is a flowchart of the stability assessment method of the present invention.

[0021] Figure 5 This is an example of a radar image showing the omnidirectional stability of a transmission tower according to the present invention.

[0022] In the diagram: 100—Variable slope avalanche slide; 101—Acceleration slide section; 102—Flow control section; 103—Horizontal testing section; 104—Support adjustment frame; 200—Embedded omnidirectional rotation testing assembly; 21—Slide base plate; 22—Static side landing platform; 51—Bearing cover plate; 52—Flexible bridging seal; 53—Embedded fine-tuning mechanism; 54—Six-dimensional force sensor; 55—Main drive shaft assembly; 56—Planetary reducer; 57—Servo drive motor; 58—Independent vibration isolation base; 300—Scaled-down model of transmission tower; 310—Main material of the model; 320—Top of the model tower; 400—Multi-source heterogeneous stability monitoring unit; 401—High-speed binocular vision camera; 401a—High-reflectivity tracking marker; 402—Miniature resistance strain gauge; 500—Upstream feeding device; 600—Multi-channel synchronous data acquisition instrument. Detailed Implementation

[0023] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0024] like Figure 1 As shown, the omnidirectional avalanche impact simulation test system for transmission towers provided by this invention consists of three subsystems working together: a variable-slope avalanche slide 100, an embedded omnidirectional rotation test assembly 200, and a multi-source heterogeneous stability monitoring unit 400. The functional objective of the entire system is to achieve omnidirectional continuous impact testing and anisotropic failure assessment of a scaled-down model 300 of a lattice-type transmission tower under complex avalanche dynamic environments, while ensuring the flatness of the bottom surface of the horizontal test section and effective protection against the particulate environment.

[0025] like Figure 1 As shown, the variable-slope avalanche slide 100 is the core flow field construction platform of this experimental system. Its purpose is to reconstruct an avalanche particle flow field driven by gravity, with clear energy evolution stages and controllable rheological characteristics. The slide adopts a three-section discontinuous slope design, supported by a high-rigidity truss base, i.e., the support and adjustment frame 104. The functions of each section of the slide are as follows: the acceleration slide section 101 is the energy source of the avalanche flow field. It uses a steep inclination angle to enable the simulated avalanche material to quickly overcome static friction at the moment of release, converting gravitational potential energy into kinetic energy, ensuring that the particle flow reaches a high Froude number flow state within a very short distance. In this embodiment, the acceleration slide section 101 is 2.5m long, with a fixed inclination angle of 50°. The bottom plate is covered with a high-hardness polytetrafluoroethylene coating, and the static friction coefficient is controlled below 0.2 to ensure that the particle material reaches a turbulent state within 0.5s after release. The top of the acceleration slide section 101 is equipped with an upstream feeding device 500, which includes a hopper with a volume of 0.2 cubic meters and a gate release mechanism.

[0026] The flow control section 102, serving as a control channel for flow evolution, is equipped with a hydraulically driven and mechanically locked variable-angle mechanical device, allowing for stepless adjustment within the range of 15° to 35°. By changing the boundary slope, the flow characteristics of the avalanche flow are controlled. Smaller inclination angles can simulate the deceleration process with increased energy dissipation, while larger inclination angles maintain the fluid's permeability, thus providing different impact velocity conditions downstream. In this embodiment, the flow control section 102 is 3.5m long, and its slope is steplessly adjustable via a hydraulic lifting mechanism. An array of mechanical pin holes is provided on the trusses on both sides of the slide, with a positioning hole every 2.5°. After the hydraulic cylinder lifts the slide to a predetermined angle, a high-strength alloy steel pin with a diameter of 20mm is inserted for mechanical locking, eliminating minor vibrations caused by hydraulic oil compression during testing.

[0027] Arc-shaped transition plates are provided between the acceleration slide section 101 and the flow control section 102, as well as between the flow control section 102 and the horizontal test section 103. In this embodiment, the radius of curvature R of the arc-shaped transition plate is 1500mm, and it is made of flexible spring steel. During the slope adjustment process, it naturally bends to form a smooth arc, eliminating the phenomenon of particle bouncing at the corner.

[0028] The horizontal test section 103 serves as a test area for the interaction between the flow field and the structure, simulating the flat terrain at the bottom of a valley. This area must withstand the normal overload when the fluid transitions from the slope to the horizontal section, as well as the subsequent horizontal impact. In this embodiment, the horizontal test section 103 is 3.0m long, and an embedded mounting countersunk hole is provided on the central axis 1.5m from the beginning of the horizontal section. The 1.5m embedding position was chosen because this location represents the stage where the particle flow has entered a fully developed horizontal motion phase after the slope transition, the flow front has not completely stopped, and the flow state has tended to stabilize, which can represent the typical flow field conditions when an avalanche impacts a building.

[0029] To address the instantaneous dynamic load impact from the acceleration slide section 101 and the normal centrifugal force pressure generated when the fluid transitions from the slope to the horizontal section at the slope inflection point, the support and adjustment frame 104 has undergone dynamic optimization design. The support and adjustment frame 104 adopts a combined steel truss structure, with reinforced lateral support members and diagonal braces at the slope inflection point to ensure that the slide slope and structure remain absolutely stable under the impact of avalanche particle flow, avoiding uncontrollable additional disturbances to the flow field caused by slide surface displacement due to structural vibration.

[0030] The entire slide system employs a modular, low-friction slide laid on a high-rigidity truss. The slide base plate is made of 10mm thick 6061-T6 aluminum alloy precision-ground plate, with a surface roughness controlled to Ra≤1.6μm to simulate a low-friction avalanche sliding interface. The effective width of the slide is 0.5m to reduce the influence of sidewall boundary effects on the central flow field. Both side walls are made of 10mm thick high-strength tempered glass to facilitate side-view observation by high-speed cameras.

[0031] like Figure 2 As shown, to achieve the concealed integration of the embedded omnidirectional rotating test assembly 200, a cylindrical through hole is milled in the center of the aluminum alloy base plate, i.e., the slide plate 21, of the horizontal test section 103 as an embedded mounting countersunk hole. In this embodiment, the diameter of the countersunk hole is 420mm, the hole diameter machining tolerance follows the H7 standard, and the outer diameter tolerance of the bearing cover plate 51 is designed to be H6, strictly controlling the theoretical single-sided clearance to about 0.5mm.

[0032] like Figure 2 As shown, to completely eliminate the interference of rotational clearance on the flow field, this embodiment adopts a structural design of bidirectional recessed platform combined with flexible thin film bridging. A precise annular recessed platform, namely the stationary side recessed platform 22, is milled around the upper edge of the mounting hole on the slide plate 21. In this embodiment, the depth of the stationary side recessed platform 22 is designed to be 2.0 mm, and the width is designed to be 15.0 mm. Correspondingly, a symmetrical annular recessed platform with the same depth and width, namely the moving side recessed platform 24, is simultaneously milled around the upper edge of the outer edge of the bearing cover plate 51.

[0033] The flexible bridging seal 52 is an annular flexible film bridging the slide plate 21 and the bearing cover plate 51. Its outer ring is precisely embedded in the stationary side sinking platform 22, and its inner ring is precisely embedded in the moving side sinking platform. In this embodiment, the flexible bridging seal 52 uses a low-hardness silicone rubber with a thickness of 1.9 mm as the substrate. Its extremely low elastic modulus provides excellent shear deformation capability, ensuring that when the bearing cover plate 51 rotates ±180° or experiences slight eccentric vibration, the film can absorb displacement through its own deformation without generating excessive radial reaction force or parasitic torque on the bearing cover plate 51. A 0.1 mm thick polytetrafluoroethylene wear-resistant coating is hot-pressed onto the side of the silicone rubber substrate facing the flow field, reducing the surface dynamic friction coefficient to below 0.1. This resists the cutting wear of high-speed particle flow and minimizes the frictional resistance during particle slippage, significantly improving the signal-to-noise ratio of the system to the weak torsional signals from the transmission tower.

[0034] The flexible bridging seal 52 is fixed to the bottom of the recessed platform on both sides using countersunk screws or industrial-grade high-strength pressure-sensitive adhesive. This bottom fixing method avoids any fasteners being exposed on the flow field surface. After installation, the PTFE wear-resistant coating surface, the upper surface of the slide plate 21, and the top surface of the bearing cover 51 are strictly on the same horizontal plane, with a height deviation controlled within ±0.1mm. This design ensures that the flexible bridging seal 52 maintains a flat bridging state when the bearing cover 51 rotates 360°, ensuring that there is no boundary layer separation interference when the underlying avalanche fluid flows through the test area.

[0035] like Figure 2As shown, the embedded omnidirectional rotation test assembly 200 is designed to provide an integrated device for the scaled-down model 300 of the transmission tower, enabling it to rotate in all directions and accurately sense accumulated impact loads. The assembly consists of a bearing cover 51, an embedded fine-tuning mechanism 53, a six-dimensional force sensor 54, a main drive shaft assembly 55, a planetary reducer 56, a servo drive motor 57, and an independent vibration isolation base 58, connected in series from top to bottom.

[0036] The bearing cover plate 51 is the contact surface that directly bears the impact and accumulation of avalanche fluid. The scaled-down model 300 of the transmission tower is installed at the center of its top surface via flange bolts. The bearing cover plate 51 is connected to the main drive shaft assembly 55 through the embedded fine-tuning mechanism 53 below. The embedded fine-tuning mechanism 53 consists of three sets of precision differential adjustment supports evenly distributed at 120°. Each set of supports includes a base locking sleeve, a high-strength alloy steel adjusting screw, and an adaptive spherical washer assembly at the top. By slightly rotating the adjusting screw with a torque wrench, micron-level displacement compensation is used to ensure that the top surface of the bearing cover plate 51 and the bottom plate of the horizontal test section 103 are coplanar and flush in three-dimensional space, eliminating local flow distortion caused by height difference at the root of the model. Assembly and debugging follow the standard procedure of coarse positioning, precision measurement, differential correction, and stress locking. During the debugging stage, a bridge-type guide rail is installed on the slide surface, and a digital dial indicator is used to continuously slide and scan across the joint between the slide plate 21 and the bearing cover plate 51. Based on the three-point plane principle, the step difference readings near the three support points are read, and compensation is achieved by slightly rotating the corresponding adjusting screw with a torque wrench. This process employs an iterative convergence method, repeatedly measuring until the step difference at all detection points on the circumference stabilizes within the ±0.1mm threshold range. Finally, while keeping the main screw stationary, the anti-loosening nut is tightened for mechanical locking.

[0037] The six-dimensional force sensor 54 is positioned directly below the bearing cover 51 and above the output end of the indexing drive mechanism. This series mounting method, with the bearing cover 51 connected above and the drive mechanism below, constitutes a force-position decoupled measurement link. The six-dimensional force sensor 54 can simultaneously sense the shear force generated by horizontal impact. and Accumulated gravity and the corresponding overturning moment and and torsional moment This layout effectively isolates the mechanical vibration, bearing friction, and lateral transmission force generated by the servo drive motor 57, ensuring that the collected electrical signals only reflect the true dynamic effects of the avalanche fluid on the scaled-down transmission tower model 300. In this embodiment, the six-dimensional force sensor 54 is a high-rigidity flange-type sensor. and The measuring range is ±2000N. The range is ±5000N to withstand the accumulated weight, torque range , , The value is ±200 N·m. The nonlinearity and hysteresis error are controlled within 0.1%FS, and the sampling frequency is set to 2kHz.

[0038] The indexing drive mechanism employs a combination of a servo drive motor 57 and a planetary reducer 56. In this embodiment, the reduction ratio is set to 1:50. The planetary reducer 56 provides a powerful self-locking torque, ensuring that the bearing cover 51 remains rigidly locked and does not passively deflect during the high-speed horizontal impact of the avalanche fluid. The servo drive motor 57 is responsible for driving the components to perform precise omnidirectional angular steps to meet the requirements for fine-grained searching of critical instability orientations. The servo drive motor 57 provides real-time feedback of the current angular position via an encoder, achieving an angular positioning accuracy better than ±0.05° and a repeatability better than ±0.02°. Before each impact test, after the servo drive motor 57 drives the bearing cover 51 to the target angle, the worm gear self-locking mechanism of the planetary reducer 56 automatically locks it. Even if the bearing cover 51 is subjected to significant horizontal shear force and torque during the fluid impact, the bearing cover 51 will not passively deflect, ensuring that the angular conditions of each impact test are strictly controllable.

[0039] The transmission tower scale model 300 is installed using a standardized flange connection method. The top center of the bearing cover 51 has a pre-drilled array of bolt holes matching the bottom flange of the transmission tower scale model 300. High-strength bolts are used to secure the four main model members 310 (i.e., the base flanges of the tower legs) of the transmission tower scale model 300 to the bearing cover 51. During installation, it is necessary to ensure that the geometric center of the transmission tower scale model 300 coincides with the rotation center of the bearing cover 51 to avoid additional centrifugal torque generated by the eccentric mass during rotation. In this embodiment, the scale ratio of the transmission tower scale model 300 is 1:50, it is assembled using aluminum alloy angle members, the model height is approximately 600mm to 800mm, and the bottom flange width is approximately 200mm.

[0040] An independent vibration isolation base 58 is installed inside the truss of the horizontal test section 103 of the slide, directly below the embedded mounting countersunk hole. The independent vibration isolation base 58 is a reinforced steel instrument chamber that does not directly contact the slide surface, thus physically isolating the high-frequency vibration interference from the avalanche fluid on the base plate. The bottom of the independent vibration isolation base 58 is equipped with a rubber damping pad to absorb the high-frequency micro-vibrations generated when particles impact the slide and transmit them downwards to the servo drive motor 57 and planetary reducer 56, preventing mechanical resonance from affecting the measurement accuracy of the six-dimensional force sensor 54. The independent vibration isolation base 58 is fixed to the foundation or independent base with anchor bolts, maintaining a physical gap with the slide support truss to completely cut off the vibration propagation path.

[0041] like Figure 3As shown, the multi-source heterogeneous stability monitoring unit 400 aims to construct a multi-dimensional sensing system capable of real-time mapping of the entire process of load input, structural response, and stability evolution of a transmission tower under avalanche impact. This monitoring unit includes a base load sensing subsystem, a non-contact displacement tracking subsystem, and a local strain acquisition subsystem.

[0042] The base load sensing subsystem utilizes a six-dimensional force sensor 54 integrated below the bearing cover plate 51 to acquire, in real time at a high sampling rate, the full three-dimensional impact force of the avalanche fluid acting on the scaled-down model 300 of the transmission tower. , , With three-dimensional torque , , This subsystem focuses on monitoring the torsional moment about the vertical axis, which is most destructive to lattice structures. And overturning moment, which serves as a benchmark for assessing external energy input.

[0043] The non-contact displacement tracking subsystem employs a high-speed binocular vision camera 401. In this embodiment, two high-speed industrial cameras are mounted on a rigid crossbeam 2.0m above the slide, with a resolution of 2048×2048, a frame rate of no less than 500fps, and a lens optical axis angle of 45°, covering the entire horizontal test section 103. High-reflectivity polyethylene tracking markers 401a with a diameter of 5mm are affixed to key nodes such as the top 320 of the transmission tower scale model 300, the ends of the crossarms, and the slope change points of the tower body. The three-dimensional coordinates of the markers are tracked in real time using a stereo matching algorithm, with a measurement accuracy better than ±0.1mm, and the lateral drift of the tower top is output in real time. and overall torsion angle .

[0044] The local strain acquisition subsystem uses a half-bridge circuit composed of resistance strain gauges. In this embodiment, the focus is on monitoring the root region of the four main model members 310 of the transmission tower scale model 300, i.e., the tower legs. 120Ω foil-type miniature resistance strain gauges 402 with a grid length of 2mm are symmetrically attached to the inner and outer surfaces of each main model member 310. Since the transmission tower scale model 300 needs to rotate 360°, the strain signal lines converge to a miniature conductive slip ring at the center of the bearing cover 51. The slip ring has more than 12 channels, and the contact resistance fluctuation does not exceed 10mΩ to prevent cable entanglement.

[0045] like Figure 4As shown, to ensure the accuracy of causal relationships, all heterogeneous sensors are connected to a multi-channel synchronous data acquisition unit 600. In this embodiment, the acquisition unit is based on a PXIe bus architecture and uses TTL level signals to construct a hardware trigger link. At the instant the gate of the upstream feeding device 500 opens, the multi-channel synchronous data acquisition unit 600 simultaneously sends high-level trigger signals to the acquisition channel of the six-dimensional force sensor 54, the trigger terminal of the high-speed binocular vision camera 401, and the dynamic strain gauge of the micro-resistance strain gauge 402. The system hardware synchronization error is controlled within 10 μs. This hardware-level synchronization mechanism ensures that the load pulse (input) and structural deformation (response) are strictly aligned on a microsecond-level time axis, eliminating analysis errors caused by phase lag. In actual operation, the system performs a synchronization verification before each impact. By applying a known standard impact pulse to the six-dimensional force sensor 54 and simultaneously recording the response start times of the three sensors, the formal impact test can only be conducted after confirming that the time deviation between the three is within a 10 μs tolerance range.

[0046] The following provides a detailed description of each step in the method for assessing the omnidirectional avalanche impact stability of transmission towers provided by this invention. For example... Figure 4 As shown, the method includes the following steps:

[0047] Step 1: System no-load calibration and parasitic stiffness modeling.

[0048] Due to the introduction of the flexible bridging seal 52, the bearing cover 51 will generate a nonlinear resistance torque during rotation due to the shear deformation of the silicone rubber film. To eliminate this systematic error, no-load calibration is required before the actual impact. Under no-load conditions without avalanche simulation material, the servo drive motor 57 is activated to drive the bearing cover 51 to continuously rotate in both directions at a constant low angular velocity of 1.0° / s within the range of 0° to 360° to eliminate the influence of inertial torque. The reason for choosing to scan in both directions is that silicone rubber material has hysteresis characteristics; the elastic rebound torque generated by the film during forward and reverse rotation is not exactly the same. Taking the average value of the forward and reverse directions can effectively eliminate the systematic deviation caused by the hysteresis effect. The multi-channel synchronous data acquisition instrument 600 records the rotation angle at a frequency of 100Hz. Readings from the 54 torque channels of the six-dimensional force sensor After acquiring complete discrete data points of rotation angle and torque, polynomial fitting is performed on the collected discrete data points using the least squares method. The choice of fitting order needs to balance accuracy and the risk of overfitting. In this embodiment, a fourth-order polynomial is used to obtain sufficient fitting accuracy, and the root mean square value of the residual is controlled within 0.05% of the sensor's full scale. Finally, the inherent parasitic stiffness characteristic curve function of the system is constructed. This function will be called in real time during each subsequent impact test to correct the torque signal online.

[0049] Step 2: Omnidirectional automated stepping impact scanning.

[0050] Standard simulated avalanche material was loaded; in this embodiment, a mixture of quartz sand and polyethylene particles with a particle size of 2 to 5 mm was used. The full-circumference scan step angle was set. A total of 72 operating points were tested, ranging from 0°, 5° to 355°. The servo drive motor 57 drove the transmission tower scale model 300 to the target impact angle, and then the self-locking mechanism of the planetary reducer 56 was rigidly locked. The high-speed binocular vision camera 401 was activated, and the gate of the upstream feeding device 500 was opened, releasing a 0.2 cubic meter flow of particles. The fluid reached a velocity of approximately 6 m / s in the acceleration slide section 101 before impacting the transmission tower scale model 300 for approximately 2.5 seconds. The multi-channel synchronous data acquisition instrument 600 synchronously triggered all sensors, recording complete time-history response data. After the impact, the accumulated particles in the horizontal test section 103 were cleaned, and the integrity of the transmission tower scale model 300 was checked to prepare for the next angle test. During the cleaning process, special care must be taken not to touch or change the installation state of the flexible bridging seal 52. Fine particles remaining on the surface of the bearing cover 51 and the flexible bridging seal 52 can be removed by compressed air blowing or vacuum adsorption. After cleaning, the servo drive motor 57 drives the bearing cover plate 51 to rotate one step angle to the next target angle, and the planetary reducer 56 locks again, preparing for the next impact. This cycle repeats until the impact test covering 72 working points with 360° full circumference is completed. The entire omnidirectional scanning process is controlled by an automated control program. The operator only needs to replenish the material and confirm the integrity of the model after each impact, which greatly improves the testing efficiency and ensures the consistency of conditions between various working conditions.

[0051] Step 3: Decoupling and spatiotemporal alignment of multidimensional data loads.

[0052] After the test is completed, for any time... Measured total torque The system automatically reads the current test angle. Corresponding parasitic drag torque Then subtract the values ​​to obtain the true torque. :

[0053] ,

[0054] in: The true torque after decoupling correction represents the actual torsional force exerted by the avalanche fluid on the scaled-down model 300 of the transmission tower around the vertical axis. It is a scalar quantity with a range covering both positive and negative directions (positive values ​​indicate clockwise torsion, and negative values ​​indicate counterclockwise torsion), and is measured in N·m. It is obtained by subtracting the parasitic component from the measured total torque. The technical effect is to eliminate the systematic error introduced by the flexible bridging seal 52 and restore the true torsional signal of the fluid on the model. For the six-dimensional force sensor 54 at time 54 Measured The total torque of the channel, which means the total torsional torque sensed by the sensor, includes the superposition of fluid torque and elastic rebound torque of flexible bridging seal 52. It is a scalar quantity with the unit N·m, and is directly acquired by the six-dimensional force sensor 54. The parasitic stiffness characteristic curve function obtained through step one, no-load calibration, at the rotation angle The value at this point represents the angle of the flexible bridging seal 52 due to shear deformation. The nonlinear resistance torque generated at the point is a scalar quantity in N·m, which is obtained by no-load forward and reverse bidirectional scanning plus least squares polynomial fitting. The technical effect is to establish a mathematical model of the nonlinear mechanical characteristics of the seal for online real-time deduction. This is a time variable, measured in seconds, and its value ranges from the TTL trigger time. Until the moment the impact ends. The current test angle of the cover plate 51 is within the range of [value range missing]. The unit is degrees, which are obtained from the encoder feedback of the servo drive motor 57.

[0055] Using the TTL trigger edge as the time zero point The 5kHz mechanical data was downsampled to 1kHz, the 1kHz visual displacement data was directly aligned, and the 5kHz strain data was downsampled to 1kHz. All these data were then aligned to a 1ms time axis to form a standardized four-dimensional dataset. This dataset includes the corrected base load. and Horizontal displacement at the top of the tower and twist angle and strain of key main materials During downsampling, an anti-aliasing low-pass filter is used to ensure that the high-frequency sampled signal does not exhibit spectral aliasing distortion after frequency reduction. At the data processing terminal, the base load curve, visual displacement curve, and strain time history curve are precisely aligned based on a unified timestamp. This allows for accurate location of the tower top torsion angle and main material strain corresponding to the moment of abrupt change in base load, thus completing a comprehensive determination of the structural instability critical point.

[0056] Step 4: Quantitative calculation of comprehensive stability criteria and identification of critical orientation.

[0057] Based on the aligned data, the system calculates the comprehensive stability evaluation index at each time step. And based on a dual criterion, determine whether the current angle belongs to the critical disaster-causing orientation. Comprehensive stability evaluation index. The calculation formula is:

[0058] ,

[0059] in: for The comprehensive stability evaluation index at time t is the reciprocal measure of the comprehensive safety margin of a 300-scale transmission tower model under avalanche impact. It is a dimensionless scalar with a value range of [value missing]. ,when This indicates that the structure has reached its design limit in terms of strength or deformation. It is obtained through weighted synthesis calculation of the base shear term, tower top displacement term, and main material strain term. The technical effect is to unify the mapping of three heterogeneous physical quantities into a single evaluation scale to achieve comprehensive judgment.

[0060] for The generalized shear force at the base, measured by the six-dimensional force sensor 54 at any given time, represents the resultant force exerted by the avalanche fluid on the scaled-down model 300 of the transmission tower in the horizontal plane. It is a scalar quantity with a value range of [missing value]. The unit is N, through Synthesized, among which and The six-dimensional force sensor 54 is respectively in and The real-time reading of the direction is a technical effect that characterizes the intensity of the horizontal resultant force of the fluid impact.

[0061] The preset structural ultimate bearing capacity refers to the maximum horizontal shear force that the scaled-down model 300 of the transmission tower can withstand under static analysis or standard calculation. It is a positive constant in N and is determined by structural mechanics methods based on the material yield strength and section properties of the scaled-down model 300 of the transmission tower. The technical effect is to provide a normalized benchmark for the shear force term.

[0062] for The horizontal displacement modulus of the tower top, measured at constant time by the non-contact displacement tracking subsystem, i.e., the high-speed binocular vision camera 401, represents the resultant displacement of the tower top 320 relative to the base in the horizontal plane. It is a scalar quantity with a value range of [value missing]. The unit is mm. The resultant displacement in the horizontal plane is obtained by solving the three-dimensional coordinates of the marker points through a stereo matching algorithm. The technical effect is to characterize the degree of lateral displacement and deformation of the overall structure.

[0063] The maximum allowable displacement threshold is determined based on structural design specifications. It means the maximum lateral displacement of the top of the transmission tower allowed by the engineering specifications. It is a normal number in mm and is determined according to the displacement limit of highly flexible structures in the transmission tower design specifications. The technical effect is to provide a normalized benchmark for the displacement term.

[0064] for The real-time axial micro-strain of the root region of the key compression main member, namely the model main member 310, is measured by the local strain acquisition subsystem, namely the micro resistance strain gauge 402. It means the linear strain of the key tower leg member under axial force. It is a dimensionless scalar with a value range covering positive and negative (positive value is tensile strain, negative value is compressive strain). It is directly measured by the strain gauge bridge circuit. The technical effect is to monitor whether the member is close to yielding or has local buckling precursors at the micro level.

[0065] The yield strain limit of the model material is the strain value corresponding to the yield point of the material used in the 300-scale transmission tower model. It is a positive constant, dimensionless, and obtained by tensile testing of materials. Its technical effect is to provide a normalized reference for the strain term.

[0066] , , These are the dimensionless weighting coefficients for the base shear force, tower top displacement, and main material strain terms, respectively. They represent the relative importance of each of the three indicators in the comprehensive evaluation, and are normal values ​​with a range of [value missing]. ( ), subscript The values ​​of correspond to the three physical dimensions of shear force, displacement, and strain, respectively. Their specific values ​​depend on the structural stiffness characteristics of the transmission tower under test and satisfy the constraint conditions. The technical effect is that the comprehensive index can be flexibly adjusted according to the stiffness distribution characteristics of different tower types to match the most sensitive failure modes.

[0067] The system iterates through the impact process and determines the current angle as the critical instability position when any of the following conditions are met:

[0068] Condition one is that the strength or deformation exceeds the limit, that is, at any time... This indicates that the structure has reached its design limit in terms of strength or deformation.

[0069] Condition two is geometric stiffness failure. Real-time calculation of the tangent stiffness of the base torque-tower top torsion angle curve:

[0070] ,

[0071] in: Let be the torsional tangential stiffness, which represents the instantaneous stiffness of a structure against torsional deformation about its vertical axis. It is a scalar quantity with a range of values ​​of 1000. The unit is N·m / rad, obtained by calculating the instantaneous slope of the load-deformation curve. Its technical effect is to characterize the structure's instantaneous resistance to deformation in the torsional direction. This indicates that the structural stiffness matrix tends to be singular. The torsional torque about the vertical axis is a scalar quantity in N·m, which is directly measured by the six-dimensional force sensor 54. The overall torsion angle at the top of the tower is a scalar quantity in rad, calculated by the non-contact displacement tracking subsystem through the rotational displacement of the tracking marker points. (Subscript) This indicates that the stiffness measure corresponds to the direction of the torsional degree of freedom.

[0072] And the tangent stiffness of the base shear force-horizontal displacement curve:

[0073] ,

[0074] in: Let be the lateral tangential stiffness, which represents the instantaneous stiffness of a structure against horizontal lateral displacement. It is a scalar quantity with a range of values ​​of [value missing]. The unit is N / mm, which is obtained by calculating the instantaneous slope of the base shear force-horizontal displacement curve. The technical effect is to characterize the instantaneous resistance to deformation of the structure in the lateral displacement direction. The base generalized shear force is expressed in N. This represents the horizontal displacement at the top of the tower, in mm. (Subscript) This indicates that the stiffness measure corresponds to the direction of the lateral displacement degree of freedom.

[0075] When the instantaneous stiffness value of 10 consecutive sampling points decreases to the initial elastic stiffness less than 5% (i.e.) When this occurs, the system automatically determines that the structure has buckled and become unstable. The slope of the linear elastic segment of the load-deformation curve in the initial stage of impact represents the original stiffness benchmark value of the structure within the elastic range. At this point, although the base load may not have reached its peak, the structure has already lost its ability to resist deformation, manifesting as overall overturning or torsional buckling. Ten consecutive sampling points are chosen as the judgment window because at a sampling rate of 1kHz, ten points correspond to a 10ms time window, which can filter out false stiffness drops caused by transient noise and respond promptly to real instability events. The 5% stiffness threshold is derived from practical experience in structural dynamics: when the tangential stiffness drops below 5% of the initial stiffness, the structure has entered the post-buckling stage, and the deformation is irreversible. Even if the external load subsequently decreases or disappears, the structure cannot recover to its original configuration. This criterion overcomes the hysteresis of traditional methods that rely solely on the peak value of the base reaction force. In the process of geometrically nonlinear instability, the singularity of the structural stiffness matrix occurs before the peak force, meaning that the structure's load-bearing capacity has been substantially lost due to the large deformation effect, but the external force sensor has not yet recorded the force decrease. Therefore, the tangent stiffness degradation criterion can detect instability earlier than the peak force criterion, and has a significant early warning advantage.

[0076] like Figure 5 As shown, based on the above dual criteria, the system evaluates 72 operating points. Peak values ​​are statistically analyzed to generate an omnidirectional stability radar map of the transmission tower. This map displays the maximum values ​​in each direction from 0° to 360° in polar coordinates. value. The direction of the prominent peak value indicates the critical anisotropic instability location of the transmission tower. In the diagram, The iso-circles form the critical instability threshold line. The region where the value curve exceeds the threshold line is the instability over-limit region, while the region where the curve lies within the threshold line is the safe region. This can be achieved by comparing different directions. The magnitude and distribution pattern of peak values ​​can provide a direct indication of the most vulnerable azimuth angles of a transmission tower. For example, for a typical four-corner steel lattice transmission tower, because its lateral stiffness in the diagonal direction is significantly lower than that in the frontal and lateral directions, radar patterns often show peak values ​​around 45°, 135°, 225°, and 315°. These directions, representing the peak values, are the critical anisotropic instability locations for this tower type, and are also key directions that require attention in disaster-resistant reinforcement design. When a certain azimuth angle appears... The value spike is accompanied by tangential stiffness. or When the azimuth drops sharply, this azimuth angle is identified as the most unfavorable disaster-causing azimuth angle, indicating that under avalanche impact at this angle, the transmission tower is most prone to premature instability due to the coupling effect of high axial pressure on the tower legs and additional torque from the fluid.

[0077] This invention integrates the embedded omnidirectional rotary test assembly 200 into the horizontal test section 103 of the variable-slope avalanche slide 100. Utilizing the coplanar bridging structure of the double-platform of the flexible bridging seal 52, mechanical gaps and steps are eliminated at the physical interface, ensuring that the dense flow state at the bottom layer is unaffected by boundary layer separation when the high-speed particle flow passes through the test area, thus constructing realistic avalanche flow field boundary conditions. A six-dimensional force sensor 54 is connected in series between the bearing cover 51 and the indexing drive mechanism in a force-position decoupling measurement link, effectively isolating the force measurement signal from drive motor vibration and bearing friction. The multi-source heterogeneous stability monitoring unit 400 constructs a full-scale sensing system from macroscopic overall deformation to microscopic local buckling through deep fusion of three layers of data: base load, tower top displacement field, and strain of key members. It is particularly noteworthy that, as a tall, flexible structure, the lateral displacement generated by the transmission tower under lateral horizontal forces couples with its own gravity to produce an additional overturning moment, i.e., the P-Delta effect in structural dynamics. This effect makes the actual stress condition of the structure more unfavorable than predicted by first-order linear analysis, manifested as a gradual decrease in the slope of the load-displacement curve, i.e., the tangential stiffness, as displacement increases. When the tangential stiffness drops to zero, the structure reaches the buckling critical point, after which any small external disturbance will lead to uncontrollable large deformations. This invention addresses this by integrating stability evaluation indices. The dual discrimination of the tangential stiffness degradation criterion can accurately capture the singularity of the stiffness matrix caused by the P-Delta effect, breaking through the traditional single criterion that relies solely on the hysteresis of the peak value of the base reaction force. It realizes the accurate characterization of the geometric nonlinear instability evolution process of the lattice transmission tower structure, and can identify the critical condition of irreversible instability of the structure in advance when the base load has not yet reached the ultimate peak value.

[0078] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of the claims of the present invention.

Claims

1. A simulation test system for omnidirectional avalanche impact on transmission towers, characterized in that, include: A variable slope avalanche slide (100) includes an acceleration slide section (101), a flow control section (102), and a horizontal test section (103) connected in sequence. The bottom plate of the horizontal test section (103) is provided with embedded mounting countersunk holes. An embedded omnidirectional rotation test assembly (200) is installed in the embedded mounting countersunk hole and includes a bearing cover plate (51), a six-dimensional force sensor (54) and an indexing drive mechanism connected in series from top to bottom. The top surface of the bearing cover plate (51) is flush with the top surface of the bottom plate of the horizontal test section (103). The bearing cover plate (51) is used to install a scaled-down model of the transmission tower (300). The indexing drive mechanism drives the bearing cover plate (51) to rotate in steps within the range of 0° to 360°. The flexible bridging seal (52) is an annular flexible film that spans between the wall of the embedded mounting countersunk hole and the outer edge of the bearing cover plate (51). The upper surface of the flexible bridging seal (52) is coplanar with the upper surface of the bottom plate of the horizontal test section (103) and the top surface of the bearing cover plate (51). The multi-source heterogeneous stability monitoring unit (400) includes the six-dimensional force sensor (54), a non-contact displacement tracking subsystem, and a local strain acquisition subsystem. The non-contact displacement tracking subsystem is used to monitor the tower top displacement and torsion angle of the scaled-down model (300) of the transmission tower in real time. The local strain acquisition subsystem is used to monitor the strain of key members of the scaled-down model (300) of the transmission tower. The three subsystems achieve time-synchronized acquisition through a synchronous trigger controller. The upper edge of the recessed mounting hole is machined with an annular stationary countersunk platform (22), and the upper edge of the outer edge of the bearing cover plate (51) is machined with an annular moving countersunk platform (24). The outer ring of the flexible bridging seal (52) is embedded in the stationary countersunk platform (22), and the inner ring is embedded in the moving countersunk platform (24). The thickness of the flexible bridging seal (52) matches the depth of the stationary countersunk platform (22) and the moving countersunk platform (24).

2. The system according to claim 1, characterized in that, The flexible bridging seal (52) is a silicone rubber film, and its side facing the flow field is covered with a polytetrafluoroethylene wear-resistant coating. The height deviation between the top surface of the bearing cover plate (51), the upper surface of the flexible bridging seal (52), and the upper surface of the bottom plate of the horizontal test section (103) is controlled within ±0.1mm.

3. The system according to claim 1, characterized in that, An embedded fine-tuning mechanism (53) is provided between the bearing cover plate (51) and the six-dimensional force sensor (54). The embedded fine-tuning mechanism (53) includes multiple sets of precision adjustment pillars evenly distributed, which are used to compensate the vertical height of the bearing cover plate (51) at the micrometer level.

4. The system according to claim 1, characterized in that, The indexing drive mechanism includes a servo drive motor (57) and a reducer (56), the reducer (56) providing a self-locking holding torque for rigidly locking the bearing cover plate (51) during avalanche fluid impact.

5. The system according to claim 1, characterized in that, The inclination angle of the acceleration slide section (101) is greater than the internal friction angle of the simulated avalanche material. The flow control section (102) achieves stepless adjustment of the slope through a hydraulic drive mechanism. Arc-shaped transition plates are provided between the acceleration slide section (101) and the flow control section (102) as well as between the flow control section (102) and the horizontal test section (103).

6. A method for evaluating the omnidirectional avalanche impact stability of a transmission tower using the system described in any one of claims 1-5, characterized in that, Includes the following steps: Step 1, System No-Load Calibration and Parasitic Stiffness Modeling: Under no-load conditions without avalanche simulation material, drive the bearing cover plate (51) to rotate and scan within the range of 0° to 360°, and record the flexible bridging seal (52) at different rotation angles. The parasitic torque generated by elastic rebound is used to construct the inherent parasitic stiffness characteristic curve function of the system. ; Step 2, Omnidirectional Automated Stepping Impact Scan: Set Step Length and Angle Drive the scaled-down model (300) of the transmission tower to the target impact angle, lock the bearing cover plate (51), release the standard equivalent of avalanche simulation fluid to impact the scaled-down model (300) of the transmission tower, and simultaneously trigger all sensors to record complete time history response data; Step 3, Load decoupling and spatiotemporal alignment of multidimensional data: for any time... Measured total torque Subtracting the current test angle Corresponding parasitic drag torque To obtain the true torque : ， in: The actual torque after decoupling correction, in units of This characterizes the actual torsional effect exerted by avalanche fluid on a scaled model of a transmission tower. For a six-dimensional force sensor at time The measured total torque, in units of This includes the superposition of fluid torque and system parasitic torque; The parasitic stiffness characteristic curve function obtained through step one, no-load calibration, at the rotation angle The value at the location, in units of This characterizes the nonlinear resistance torque generated by shear deformation in flexible bridging seals. For time variables, the unit is ; The current test angle of the cover plate is within the range of [value range missing]. The unit is degrees (°). The corrected base load data, tower top displacement data and main material strain data are synchronized and aligned on a unified time axis to construct a multidimensional dataset with one-to-one correspondence between load, displacement and strain. Step 4: Quantitative calculation and critical orientation identification of comprehensive stability criteria: Calculate the comprehensive stability evaluation index. : ， in: for The comprehensive stability evaluation index at time step is a dimensionless number. This indicates that the structure has reached its design limits in terms of strength or deformation; for Generalized shear force of the base measured by a six-dimensional force sensor at any time, in units of ,pass Synthesize to obtain; and Six-dimensional force sensors at and Real-time reading of direction. The preset structural ultimate bearing capacity, in units of The yield strength and cross-sectional properties of the material are determined based on the scaled-down model of the transmission tower; for The horizontal displacement modulus at the top of the tower, measured by the non-contact displacement tracking subsystem at constant time, in units of ; The maximum allowable displacement threshold is determined based on structural design specifications, and the unit is 1. ; for The real-time axial micro-strain of the key compression material, measured by the local strain acquisition subsystem, is dimensionless. is the yield strain limit of the model material, which is a dimensionless number obtained from material mechanics experiments; , , These are the dimensionless weighting coefficients for the base shear term, tower top displacement term, and main material strain term, respectively, with values ​​ranging from [value range missing]. Its specific value depends on the structural stiffness characteristics of the transmission tower under test, and satisfies ; The current angle is determined to be a critical instability azimuth when any of the following conditions are met: Condition 1: Strength or deformation exceeds limits: at any time ; Condition 2, Geometric stiffness failure: Real-time calculation of the tangential stiffness of the base torque versus tower top torsion angle curve. and the tangential stiffness of the base shear force versus horizontal displacement curve When the instantaneous stiffness value of a continuously preset number of sampling points decreases to the initial elastic stiffness... When the value is below the preset ratio, the structure is judged to have buckling instability; in: Torsional tangential stiffness, unit: It characterizes the instantaneous ability of a structure to resist torsional deformation; Torsional moment about the vertical axis, in units of It is directly measured by a six-dimensional force sensor; The overall twist angle at the top of the tower, in units of The value is obtained by the non-contact displacement tracking subsystem. The lateral tangential stiffness is expressed in units of . It characterizes the instantaneous ability of a structure to resist lateral displacement; The elastic stiffness reference value in the initial stage of impact is determined by the slope of the linear elastic segment of the load-deformation curve; when or When this occurs, it indicates that the structural stiffness matrix tends to be singular, resulting in geometric nonlinear instability; Repeat steps two through four until a 360° omnidirectional scan is completed, generating an omnidirectional stability radar map of the transmission tower and accurately pinpointing the most unfavorable azimuth angle that causes the transmission tower to experience anisotropic critical instability.

7. The method according to claim 6, characterized in that, In step one, the bearing cover plate (51) is driven to perform continuous rotational scanning in both forward and reverse directions within the range of 0° to 360° at a constant low angular velocity. The collected rotation angle-torque discrete data points are then fitted using a polynomial method with the least squares method to construct the parasitic stiffness characteristic curve function. .

8. The method according to claim 7, characterized in that, In step three, a TTL level trigger signal is used as the time zero point. Mechanical data, visual displacement data, and strain data with different sampling rates are uniformly downsampled onto the same frequency time axis to form a standardized multidimensional dataset.

9. The method according to claim 8, characterized in that, In step four, the preset number is 10 consecutive sampling points, and the preset ratio is the initial elastic stiffness. 5%; the omnidirectional stability radar map is displayed in polar coordinates. Maximum in each direction value, The direction of the prominent peak value is the critical anisotropic instability orientation of the scaled-down model of the transmission tower.

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