In-situ dismantling method for power transmission tower

Abstract

The invention discloses a power transmission tower in-situ dismantling method which comprises the following steps that an iron tower is divided into a plurality of tower sections, a main material of the iron tower is held by a hoop assembly, the hoop assembly is connected with a portal frame through four tackle blocks to form a fixing system of an iron tower lifting base plane, and a winch is connected with a ground anchor through a pull rod. The pulley block is connected with the hoop assembly and can apply pulling force or releasing force to the hoop assembly; the method comprises the following steps of: dismantling an iron tower section by section from bottom to top by adopting an inverted dismantling method, loosening anchor screws of the iron tower, starting all winches, slowly pulling the iron tower to leave the ground, dismantling the lowest tower section, pulling out the tower sections by adopting a rail type heavy-load AGV (Automatic Guided Vehicle), and hoisting the dismantled tower sections out of a construction area by a crane, so that high-altitude operation is not needed, and the danger coefficient is low; under the control of the system, the purpose of simply, safely and efficiently disassembling the tower is achieved, the construction process is greatly simplified, the working efficiency is improved, and the time and danger of high-altitude operation are reduced.

Description

Technical Field

[0001] This invention relates to the field of power transmission tower technology, and specifically to a method for in-situ dismantling of power transmission towers. Background Technology

[0002] In recent years, with the adjustment of the power grid structure, some old lines have completed their service life and need to be rebuilt or upgraded, resulting in a large number of decommissioned lines. These lines suffer from years of disrepair, aging of towers, conductors, and major components, and are also susceptible to external damage, making them a weak link in power grid safety management. Furthermore, with rapid urban development, some transmission lines have become obstacles to engineering projects, railways, highways, subways, and shipping, requiring timely relocation or dismantling to make way for urban development. Faced with the challenges brought by a large number of decommissioned lines and rapid urban development, how to assemble transmission towers in a simple, safe, and efficient manner is a practical issue that the power industry urgently needs to address.

[0003] Currently, in my country's power industry, the traditional methods for dismantling transmission towers mainly include cutting and dismantling, and crane lifting and dismantling. The cutting method requires determining the tower's tilting direction based on the site conditions, removing the steel wire ropes and ground anchors on one side of the tilt direction, then using an oxy-acetylene torch to cut the outrigger closest to the steel wire ropes on the other side, tightening the steel wire ropes to allow the tower to fall slowly. After the tower falls, the tower materials are then dismantled from top to bottom. This method has a high risk factor, makes it difficult to control the tower's tilting direction, requires a large site area, and incurs high compensation costs.

[0004] The crane-lifting dismantling method involves dismantling in sections from top to bottom. One section is dismantled, then another is lifted away, and so on until all sections are dismantled. This method requires working at heights, is extremely dangerous, and is very expensive and difficult to implement. For tall and heavy towers, extremely large cranes with very high tonnage are needed, requiring long assembly times, demanding specific environmental conditions, and even slight settlement of the lifting foundation can severely affect the displacement of the tower's top, making implementation significantly more difficult. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of existing technologies by providing a method for in-situ dismantling of power transmission towers, thereby solving the problems mentioned in the background art.

[0006] To achieve this objective, the present invention adopts the following technical solution:

[0007] A method for in-situ dismantling of power transmission towers includes the following steps:

[0008] S1. Calculate the downward pressure on the tower, design the bearing capacity of the gantry frame based on the downward pressure, and determine the burial depth of the ground anchor.

[0009] S2. Perform a wind load stress analysis on the entire tower and calculate the optimal prestress of the guy wires;

[0010] S3. The main tower structure is secured with clamping assemblies. The clamping assemblies are connected to the gantry frame via four pulley blocks to form a fixed system for the tower lifting base. The winches are connected to the ground anchors via pull bars and to the clamping assemblies via pulley blocks, enabling the application of tension or release force to the clamping assemblies. The pulley blocks are connected to the gantry frame via tension sensors, which transmit the tension load of each leg of the tower and the load of the entire gantry frame to the control system in real time. The control system then adjusts the working status of each winch in real time.

[0011] S4. Install acceleration sensors on each of the four legs of the tower. The acceleration sensors transmit the real-time data to the control system. The control system calculates the corresponding tilt angle value and smooths and filters the tilt angle data. At the same time, it quickly determines the winch closest to the highest point of the platform in the current state, calculates the difference in the position of other winches reaching the highest point, and drives the corresponding winch to perform rope winding or unwinding operations so that all the legs of the tower are at the same height.

[0012] S5. A Bayesian fusion algorithm using a Kalman filter is used to fuse data from multiple sensors to obtain more reliable data information.

[0013] S6. Divide the tower into multiple sections and dismantle it section by section from bottom to top using the reverse dismantling method. Loosen the anchor bolts of the tower, start all the winches, and slowly pull the tower off the ground. Dismantle the bottom section, use a rail-mounted heavy-duty AGV to pull the section out, and then use a crane to lift the dismantled section out of the construction area. The winches slowly lower the remaining tower, and then move the clamp assembly up one section to hold the remaining main tower material. Repeat the above operation to dismantle the tower.

[0014] S7. During the tower dismantling operation, the tension of the guy wires is adjusted according to the wind protection requirements and the tower's tilt condition, so that the tower as a whole can achieve self-balance.

[0015] As a preferred method for in-situ dismantling of power transmission towers, step S1 specifically includes:

[0016] S11. Calculate the downward pressure on the tower:

[0017]

[0018]

[0019] In the formula This is the initial stress of the upper tension wire. This is the initial stress of the lower layer of guy wire. The weight of the tower itself;

[0020] S12. Calculate the vertical bearing capacity of a single pile of the gantry frame:

[0021]

[0022] In the formula Where L is the ultimate lateral resistance, h is the circumference of the circular pile, and h is the soil layer thickness. This is the standard value of the limiting side resistance. This is the soil liquefaction reduction factor;

[0023] Calculate the total ultimate lateral resistance of a single pile of the gantry crane in each soil layer:

[0024]

[0025] Calculate the limiting end resistance:

[0026]

[0027] In the formula This is the standard value of the extreme end resistance. This represents the cross-sectional area of ​​the foundation pile;

[0028] Calculate the design value of total side drag:

[0029]

[0030] In the formula This is the partial factor for the vertical bearing capacity resistance of the pile foundation;

[0031] Calculate the design value of the end resistance:

[0032]

[0033] Calculate the design value of the vertical bearing capacity of the foundation pile:

[0034]

[0035] In the formula This is the partial factor for the vertical bearing capacity resistance of the pile foundation;

[0036] S13. Determine the burial depth of the ground anchor:

[0037]

[0038]

[0039] In the formula The soil volume for the ground anchor pull-out resistance. For soil density, Let be the safety factor for the pull-out resistance of the ground anchor, 'a' be the angle between the direction of the force on the ground anchor and the ground surface, and 'd' be the width of the ground anchor. Where is the length of the ground anchor, and h is the burial depth of the ground anchor. For soil pull-out angle.

[0040] As a preferred method for in-situ dismantling of power transmission towers, step S2 specifically includes:

[0041] S21. Calculate the magnitude of the wind load on the tower:

[0042]

[0043] In the formula This is the standard value of wind load. Basic wind pressure, This is the wind pressure height variation coefficient. This is the wind load shape coefficient. This is the wind load adjustment factor. The calculated value of the projected area to withstand wind pressure;

[0044] S22. Calculate the moment at the base of the tower, and obtain the corresponding calculated values ​​according to different wind load combinations:

[0045]

[0046] In the formula Let q be the moment of the wind load on the lifting root, q be the wind load of each segment, and h be the height of the center of gravity of each wind load relative to the root of the tower.

[0047] When calculating the wind load on the tower in segments, This is the algebraic sum of the moments of each wind load on its root.

[0048] S23. Determine the wind speed corresponding to the wind pressure according to the wind force classification standard;

[0049] S24. Based on the reference standard for prestressed guy wires and combined with the above stress analysis of the tower, the optimal prestress of the guy wires is determined.

[0050] As a preferred method for in-situ dismantling of transmission towers, the specific calculation process for the tilt angle value in step S4 is as follows:

[0051] S41. Calculate the roll angle and pitch angle of each tower leg:

[0052]

[0053]

[0054] In the formula The roll angle of the object's posture is the rotation angle around the X-axis. The pitch angle of the object's posture is the rotation angle around the Y-axis. , , These are the triaxial acceleration components measured by the accelerometer;

[0055] S42. Calculate the tilt angle of the iron tower relative to the natural gravity axis:

[0056]

[0057] Convert the above radian values ​​to natural angle values.

[0058] As a preferred method for in-situ dismantling of power transmission towers, the specific process of smoothing and filtering the tilt angle data in step S4 is as follows:

[0059] S43. The accelerometer reads the acceleration values ​​of the three axes at millisecond intervals and calculates the aforementioned angle values ​​in real time to obtain a data sequence of tilt angle values. Then, a Kalman filter is used to iterate through the tilt angle value sequence to predict the tilt angle value.

[0060]

[0061] In the formula, X is the predicted value of the state at time k based on the information at time k-1, A is the state transition matrix, and B is the control input matrix. For the control input at time k, initially set A=1 in the formula. =0;

[0062] S44. Calculate the covariance of the predicted tilt angle values:

[0063]

[0064] In the formula Let be the covariance matrix of the predicted state at time k. Let Q be the covariance matrix of the optimal state estimate at time k-1, and let Q be the system noise covariance matrix.

[0065] S45. Update Kalman coefficients:

[0066]

[0067] In the formula Let H be the Kalman gain at time k, H be the observation matrix, and R be the observation noise covariance matrix. Initially, H is set to 1 in the formula.

[0068] S46. Calculate the current optimal value and the covariance of the optimal value:

[0069]

[0070]

[0071] In the formula Let k be the observation value at time k;

[0072] S47. After iterating through all the data in the data sequence, the effective tilt angle value after filtering can be obtained.

[0073] As a preferred method for in-situ dismantling of power transmission towers, step S5 specifically includes:

[0074] S51. Based on the system's dynamic model, use the sensor's state estimate and covariance estimate from the previous moment to predict the sensor's state and covariance at the current moment; when new detection data is obtained, calculate the Kalman gain according to the update equation, and then update the state estimate and covariance estimate.

[0075] S52. Calculate the weights of each Kalman filter result:

[0076]

[0077] In the formula This is the covariance estimate of the Kalman filter at time k;

[0078] S53. Bayesian fusion using weighted averaging:

[0079]

[0080]

[0081] In the formula These are the estimated states after fusion. This is the estimated value of the fused covariance.

[0082] As a preferred method for in-situ dismantling of power transmission towers, step S7 specifically includes:

[0083] S71. Calculate the operating tension of the guy wires on the windward and leeward sides under different guy wire prestresses:

[0084]

[0085] In the formula For the dynamic coefficient, Let H be the moment of wind load on the base of the tower, and H be the height of the guy wire point from the ground. The angle between the wind direction and the guy wire. The angle between the guy wire and the ground;

[0086] S72. Adjust the tension of the guy wires according to different guy wire prestresses to adjust the attitude of the tower so that the tower as a whole can achieve self-balance.

[0087] The beneficial effects of this invention are:

[0088] The in-situ dismantling method for transmission towers of this invention employs a bottom-up, segment-by-segment dismantling approach. A winch slowly pulls the tower off the ground, prioritizing the dismantling of the lowest segment. A heavy-duty AGV (Automated Guided Vehicle) is used to pull the segment out, and a crane lifts it out of the construction area. The winch then slowly lowers the remaining tower, and the clamp assembly is moved up one segment to secure the remaining tower structure. This process is repeated for complete dismantling. This eliminates the need for high-altitude work, resulting in a low risk factor. Furthermore, during dismantling, the invention analyzes the tower's stress characteristics and, without removing the existing guy wires, gradually and synchronously tightens the winch's guy wires at equal intervals to maintain constant lateral tension. Simultaneously, based on sensor data and robust control, the lateral tension is fine-tuned to ensure the tower's sway is less than the system's preset value. During descent, synchronously tightened four-way guy cables control the tower to remain perpendicular to the ground. Under system control, this method achieves a simple, safe, and efficient dismantling process, significantly simplifying the construction process, improving work efficiency, and reducing the time and danger of high-altitude work. Attached Figure Description

[0089] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments of the present invention will be briefly described below. Obviously, the drawings described below are merely some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without any creative effort.

[0090] Figure 1 This is a tower type diagram of the long-span guyed tower described in this invention.

[0091] Figure 2 This is a system schematic diagram of the in-situ dismantling method for power transmission towers described in this invention.

[0092] Figure 3 This is a diagram showing the relationship between the elongation and stress of the steel wire rope described in this invention.

[0093] Figure 4 This is a simplified diagram of the iron tower model described in this invention.

[0094] Figure 5 This is a stress diagram of the iron tower under wind load as described in this invention.

[0095] Figure 6 This is a diagram showing the stress on the pull-wire under strong wind load as described in this invention.

[0096] Figure 7This is a diagram showing the magnitude of the tension at the drawstring node as described in this invention. Detailed Implementation

[0097] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0098] The accompanying drawings are for illustrative purposes only and are schematic diagrams, not actual images. They should not be construed as limiting the scope of this patent. To better illustrate the embodiments of the present invention, some parts in the drawings may be omitted, enlarged, or reduced, and do not represent the actual dimensions of the product. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.

[0099] In the accompanying drawings of the embodiments of the present invention, the same or similar reference numerals correspond to the same or similar components. In the description of the present invention, it should be understood that if terms such as "upper," "lower," "left," "right," "inner," and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the terms used to describe positional relationships in the drawings are only for illustrative purposes and should not be construed as limiting the present patent. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0100] In the description of this invention, unless otherwise explicitly specified and limited, the term "connection" or similar designation indicating a connection between components should be interpreted broadly. For example, it can refer to a fixed connection, a detachable connection, or an integral part; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can refer to the internal communication between two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0101] like Figure 1 As shown, the present invention provides a method for in-situ dismantling of power transmission towers, comprising the following steps:

[0102] S1. Calculate the downward pressure on the tower, design the bearing capacity of the gantry frame based on this downward pressure, and determine the burial depth of the ground anchors. The specific calculation process is as follows:

[0103] like Figure 1 As shown, based on the design of the gantry and the control requirements for the lifting and lowering of the guyed tower, it is necessary to calculate the load-bearing foundation of the system. The self-weight of the tower being dismantled in this embodiment is 164.5 tons, and the pulling force of the winch used is as follows:

[0104] Table 1: Winch Cable Values

[0105] Pulling lines pull wire specifications Initial stress of the tension wire (tons) upper layer 2XS-907 14.51 lower level 1XS-907 7.26

[0106] S11. Calculate the downward pressure on the tower:

[0107] The vertical component of the force on the string is

[0108] ton

[0109] The downward pressure on the tower is ton

[0110] In the formula This is the initial stress of the upper tension wire. This is the initial stress of the lower layer of guy wire. The weight of the tower itself;

[0111] S12. After determining the total pressure under the tower, calculate the vertical bearing capacity of a single pile of the gantry crane based on the site conditions:

[0112] The pile type used in this embodiment is a mud-wall drilled (percussion) cast-in-place pile, and the partial factor for the vertical bearing capacity of the pile foundation is: The pile type is circular, with a diameter d = 1000 mm, a circumference L = 3.1415926 m, and a cross-sectional area of... ;

[0113] In this embodiment, the first soil layer at the construction site is plain fill, and the standard value of the ultimate lateral resistance is... Soil layer thickness h = 2.1m, soil liquefaction reduction factor Calculate the limiting side resistance ;

[0114] The second soil layer is silt, and the standard value of the ultimate lateral resistance is... Soil layer thickness h = 26.6 m, soil liquefaction reduction factor Calculate the limiting side resistance ;

[0115] The third soil layer is medium sand, with the standard value of ultimate lateral resistance being... Soil layer thickness h = 3.4 m, soil liquefaction reduction factor Calculate the limiting side resistance ;

[0116] Calculate the total ultimate lateral resistance of a single pile of the gantry crane in each soil layer:

[0117]

[0118] Standard value of extreme end resistance Calculate the limiting end resistance:

[0119]

[0120] Calculate the design value of total side drag:

[0121]

[0122] Calculate the design value of the end resistance:

[0123]

[0124] Calculate the design value of the vertical bearing capacity of the foundation pile:

[0125]

[0126] Based on the above calculations, this embodiment uses a large slab foundation combined with cast-in-place piles. The bearing capacity of the entire new foundation is: 4*1612+4681.04=11129.07KN=1112.907T. Since the self-weight of the tower is 164.5 tons, plus the downward pressure of the wire rope of 54.63 tons and the weight of the gantry frame hanging components of 42 tons, the total downward pressure on the tower body is 261.13 tons. The maximum bearing capacity of the new foundation is calculated to be 1112.907 tons, with a safety factor of 4.26, which meets the construction requirements.

[0127] S13. In this embodiment, a 20-ton ground anchor with a 2m*0.5m specification is mainly used with a corresponding ground anchor rod to determine the burial depth of the ground anchor:

[0128]

[0129]

[0130] In the formula The soil volume for the ground anchor pull-out resistance. For soil density, take ; Let k = 2.0 be the safety factor for the pull-out resistance of the ground anchor; a is the angle between the force direction of the ground anchor and the ground surface, taken as a = 45°; d is the width of the ground anchor. Where is the length of the ground anchor, and h is the burial depth of the ground anchor. For the soil pull-out angle, take ;

[0131] Calculations show that the anchor burial depth is 3m. The anchor pull-out resistance is then verified using this depth. The specific verification results are shown in the table below.

[0132] Table 2: Calculation Table for Pull-out Force of Ground Anchors

[0133]

[0134] Calculations show that the anchor burial depth can meet the construction requirements.

[0135] S2. Perform a wind load stress analysis on the entire tower and calculate the optimal prestress of the guy wires. The specific calculation process is as follows:

[0136] Ultra-high voltage (UHV) transmission lines are typical tall structures, with wind load being their primary controlling load. Accidents of transmission towers collapsing due to severe vibrations caused by strong winds are frequent. Unlike traditional self-supporting transmission towers, the high flexibility of guyed towers makes them more sensitive to wind loads. The difficulties in wind-resistant design of guyed transmission towers mainly include the following aspects: First, guyed towers are complex spatial structures composed of tower heads, main columns, and guy wires, exhibiting strong geometric nonlinearity. This characteristic poses significant challenges to the research and analysis of guyed towers. Second, the lack of research materials, analysis reports, measured data on wind vibration response, and experimental data related to guyed towers has led to a lack of in-depth understanding of their static and dynamic characteristics. Third, while current national standards and publications mostly specify the wind vibration coefficient for self-supporting transmission towers, they rarely address the issue of determining the wind vibration coefficient for guyed transmission towers.

[0137] Therefore, pattern recognition is required for guyed tower systems, and the lifting system design should be carried out based on the guyed tower model. Reasonable model simplification can reduce complexity, improving computational efficiency and saving computation time while ensuring accuracy. The simplification of the guyed tower mechanical model includes both structural simplification and guy wire simplification. Guy wire simplification can typically employ the bilinear rod element method or the multi-segment linear rod element method. The multi-segment linear rod element method offers higher accuracy than the bilinear rod element method; therefore, this embodiment uses the multi-segment linear rod element method, based on the relationship between wire rope elongation and stress (see reference). Figure 3 The final simplified mechanical model of the single-column guyed tower is as follows: Figure 4 As shown.

[0138] During construction, guyed towers rely on taut guy wires to maintain their balance. The equilibrium state of the tower under the weight of the tower body, conductors, and guy wire tension is called the initial state, and the stress in the guy wires in the initial state is called the initial prestress of the guy wires. In the design of guyed towers, the selection of the initial prestress of the guy wires is crucial to the strength, stiffness, and stability of the tower; therefore, wind load analysis of the entire tower is necessary.

[0139] S21. Calculate the magnitude of the wind load on the tower:

[0140]

[0141] In the formula This is the standard value of wind load. Basic wind pressure, This is the wind pressure height variation coefficient. This is the wind load shape coefficient. This is the wind load adjustment factor. The calculated value of the projected area to withstand wind pressure;

[0142] S22. Calculate the moment at the base of the tower, and obtain the corresponding calculated values ​​according to different wind load combinations:

[0143]

[0144] In the formula Let q be the moment of the wind load on the lifting root, q be the wind load of each segment, and h be the height of the center of gravity of each wind load relative to the root of the tower.

[0145] When calculating the wind load on the tower in segments, This is the algebraic sum of the moments of each wind load on its root.

[0146] S23. Based on the wind force level classification standard in Table 3, determine the wind speed corresponding to the wind pressure.

[0147] Table 3: Wind Force Classification Standards

[0148] Wind force level Wind speed (m / s) Wind pressure (kg / m²) 0 0-0.2 0-0.0025 1 0.3-1.5 0.0056-0.014 2 1.6-3.3 0.016-0.68 3 3.4-5.4 0.72-1.82 4 5.5-7.9 1.89-3.9 5 8.0-10.7 4-7.16 6 10.8-13.8 7.29-11.9 7 13.9-17.1 12.08-18.08 8 17.2-20.7 18.49-26.78 9 20.8-24.4 27.04-37.21 10 24.5-28.4 37.52-50.41 11 28.5-32.6 50.77-66.42

[0149] S24. According to the relevant provisions of the "Technical Specification for Design of 110kV~750kV Overhead Transmission Lines DLT5154—2012", "Design Specification for Tall Structures GB50135—2019" and "Technical Specification for Design of Tower Structures of Overhead Transmission Lines DLT5154—2012", when the winch is working, the prestress of the guy wire should be referenced to the above standards. Combined with the above stress analysis of the tower, the optimal prestress of the guy wire can be obtained.

[0150] In this embodiment, the upper guy wire uses two combined 6-strand steel wire ropes with a diameter of 34mm and a breaking strength of 769KN; the lower guy wire uses one steel wire rope of the same specification. Different prestresses are applied to the guy wires, and the stress state and displacement of key parts of the tower are calculated using ANSYS finite element analysis software at a wind speed of 30m / s (see reference). Figure 4 and Figure 5 The calculation results are shown in the table below:

[0151] Table 4: Stress State and Offset Data of the Iron Tower

[0152]

[0153] Based on the above analysis, the following conclusions can be drawn:

[0154] (1) Under strong wind load, the deformation of the guyed tower is mainly the rigid body rotation of the main material around the bottom hinge point;

[0155] (2) The stress and nodal displacement of the guyed tower members change linearly with the initial prestress of the guy wire in the initial state and nonlinearly under strong wind load.

[0156] (3) When the initial prestress of the guy wire is less than the critical prestress of the guy wire, the main material is balanced mainly by the tension of the guy wire on the windward side and the wind load. Therefore, as the initial prestress increases, the displacement of the guy wire tower nodes decreases, while the working stress of the guy wire, the axial force of the members, and the reaction force of the main material support remain basically unchanged. When the prestress is 50 MPa, the offset and stress at the positions of the upper and lower guy wires of the tower are within the design requirements. According to calculations, the stability of the control system is highest when the actual stress of the wire rope is 80 MPa.

[0157] S3, such as Figure 2 As shown, this embodiment uses a clamp assembly to hold the main tower material. The clamp assembly is connected to the gantry frame through four pulley blocks to form a fixed system for the tower lifting base. The winch is connected to the ground anchor through a pull bar and to the clamp assembly through the pulley blocks, which can apply tension or release force to the clamp assembly. The pulley blocks are connected to the gantry frame through a tension sensor, which transmits the tension bearing status of each leg of the tower and the load of the entire gantry frame to the control system in real time. The control system adjusts the working status of each winch in real time.

[0158] S4. Accelerometers are installed on each of the four legs of the tower. These sensors transmit real-time data to the control system, which calculates the corresponding tilt angle and smooths the data. Simultaneously, it quickly identifies the winch closest to the highest point of the platform in the current state, calculates the difference in position between the other winches, and drives the corresponding winch to perform rope winding or unwinding operations, ensuring all legs of the tower are at the same height. The specific analysis process is as follows:

[0159] The lifting system uses four pulley blocks and clamps for support during the lifting and lowering of the main tower structure. To maintain safety during the lifting process, controlling the levelness of the lifting system is essential. However, the working plane formed by the four-point support has the problem of static instability, which can easily lead to the phenomenon of "virtual support" in application, where one leg is not under force or is suspended in the air, causing uneven force on the winch at each point. Therefore, it is necessary to suppress the "virtual support" phenomenon through control algorithms during the leveling process.

[0160] The essence of leveling is to adjust any two intersecting straight lines on the platform plane to a horizontal state. Only when the two straight lines on the platform plane are perpendicular to each other will they not interfere with each other during their respective leveling processes. In practice, accelerometers need to be installed in the X and Y directions of the platform to measure the horizontal tilt angle of the platform in the X and Y directions, respectively.

[0161] This embodiment adopts a "chasing" leveling method with position error control based on the characteristics of the system. The implementation process is as follows: First, the tilt angle signals transmitted back by two sensors are obtained. According to the corresponding algorithm, the winch that is closest to the highest point of the platform in the current state is quickly determined. At the same time, the difference between the positions of other winches reaching the highest point is calculated and transmitted to the control system of the corresponding winch. The winch is driven to wind up and unwind the rope. After multiple adjustments, all the outriggers of the tower will be at the same height, thereby achieving the goal of leveling.

[0162] Specifically, the calculation process for the tilt angle value in this embodiment is as follows:

[0163] S41. Calculate the roll angle and pitch angle of each tower leg:

[0164]

[0165]

[0166] In the formula The roll angle of the object's posture is the rotation angle around the X-axis. The pitch angle of the object's posture is the rotation angle around the Y-axis. , , These are the triaxial acceleration components measured by the accelerometer;

[0167] The above calculation formula is applied to the specific case of detecting tower tilt. Since the measured vertical acceleration component is always greater than zero, the formula actually only uses the top branch. According to technical specifications, the basic tilt angle data that the online tower tilt monitoring device needs to collect and transmit back from the sensor are the longitudinal tilt angle and the transverse tilt angle. By reasonably positioning the sensor on the tower, for example, with the Z-axis pointing upwards and the X-axis aligned with the power line direction, the above method yields... Angle and The angle corresponds to the angle of inclination along the line and the angle of inclination along the horizontal line.

[0168] S42. Calculate the tilt angle of the iron tower relative to the natural gravity axis:

[0169]

[0170] The data obtained through the above formula is in radians. By converting radians to angles, the natural angle value can be obtained. However, since the tower is located in an outdoor environment, it is often affected by external weather, geological conditions, and its own internal factors. Besides actual swaying and tilting, there is often interference from vibration clutter. Accelerometers, being highly sensitive, are easily affected by this noise. Therefore, a Kalman filter algorithm is needed to smooth the initial data and enhance its effectiveness.

[0171] The specific process of smoothing and filtering the tilt angle data in this embodiment is as follows:

[0172] S43. The accelerometer reads the acceleration values ​​of the three axes at millisecond intervals and calculates the aforementioned angle values ​​in real time to obtain a data sequence of tilt angle values. Then, a Kalman filter is used to iterate through the tilt angle value sequence to predict the tilt angle value.

[0173]

[0174] In the formula, X is the predicted value of the state at time k based on the information at time k-1, A is the state transition matrix, and B is the control input matrix. For the control input at time k, initially set A=1 in the formula. =0;

[0175] S44. Calculate the covariance of the predicted tilt angle values:

[0176]

[0177] In the formula Let be the covariance matrix of the predicted state at time k. Let Q be the covariance matrix of the optimal state estimate at time k-1, and let Q be the system noise covariance matrix.

[0178] S45. Update Kalman coefficients:

[0179]

[0180] In the formula Let H be the Kalman gain at time k, H be the observation matrix, and R be the observation noise covariance matrix. Initially, H is set to 1 in the formula.

[0181] S46. Calculate the current optimal value and the covariance of the optimal value:

[0182]

[0183]

[0184] In the formula Let k be the observation value at time k;

[0185] S47. After iterating through all the data in the data sequence, the effective tilt angle value after filtering can be obtained.

[0186] S5. The in-situ dismantling system for power transmission towers used in this embodiment includes multiple sensors. The primary goal of designing a multi-sensor system is to combine, correlate, and integrate measurement data from multiple sensors and relevant information from related databases to obtain more comprehensive and reliable data. However, many problems arise in achieving this goal, such as data correlation, sensor uncertainty, and data management. The most fundamental problem lies in the inherent uncertainty in the sensor measurement system. This uncertainty arises not only from measurement inaccuracies and noise but also from the inconsistency of individual sensors. This embodiment addresses the issue of how to handle the uncertainty and inconsistency of data from various sensor nodes in sensor network data fusion. Depending on whether filters are applied to sensor data, fused data, or both, a Bayesian fusion algorithm using a Kalman filter is employed to fuse data from multiple sensors. The specific fusion process is as follows:

[0187] S51. Based on the system's dynamic model, use the sensor's state estimate and covariance estimate from the previous moment to predict the sensor's state and covariance at the current moment; when new detection data is obtained, calculate the Kalman gain according to the update equation, and then update the state estimate and covariance estimate.

[0188] S52. Calculate the weights of each Kalman filter result:

[0189]

[0190] In the formula This is the covariance estimate of the Kalman filter at time k;

[0191] S53. Bayesian fusion using weighted averaging:

[0192]

[0193]

[0194] In the formula These are the estimated states after fusion. This is the estimated value of the fused covariance.

[0195] The Bayesian fusion algorithm using Kalman filters in this embodiment solves the problems of uncertainty and inconsistency in sensor data. The algorithm combines the improved Bayesian fusion algorithm with Kalman filters, proving that Kalman filters can improve the sum of squared residuals and the variance of the estimated values. It can be applied to the complex multi-sensor data fusion scenario in this embodiment.

[0196] S6. In this embodiment, the long-span iron tower is divided into multiple tower sections. The tower is dismantled section by section from bottom to top using a reverse dismantling method. Since each tower section of the long-span iron tower has the same size and structure, a bottom-up sequence is adopted. After each section is dismantled, a rail-mounted heavy-duty AGV transport vehicle pulls the tower section out, and then a crane lifts the dismantled tower section out of the construction area. A winch slowly lowers the remaining iron tower, and then the clamp assembly is moved up one tower section to clamp the remaining main iron tower material. The above operation is repeated to dismantle the entire iron tower. The overall construction process is shown in Table 5.

[0197] Table 5: Steps for dismantling the iron tower

[0198] Demolition of tower section Demolition steps Tower Section 6 (1) The clamp assembly holds the main tower body material tightly, the old tower foundation bolts are loosened, all winches are operated, the old tower is slowly lifted off the ground and left to stand for 12 hours; (2) The tower section ⑥ is dismantled, the steel is recycled, and then the winches are operated to slowly lower the tower body, and the main tower body material is placed on the ground. Tower Section 5 (1) Manually move the clamp assembly up one tower section and clamp the main tower material of the upper layer; (2) The winch lifts the tower body, removes the flange connection bolts, and the lower tower section is transported out by a level cart and lifted away by a crane; (3) The winch slowly lowers the tower body and the main tower material lands on the ground. Tower Section 4 The same method as for dismantling tower section ④ is used to finally remove the temporary guy wires on the lower level. Tower Section ③ The same method as for dismantling tower section ④ is used to finally remove the upper temporary guy wires. Tower head and crossbeam Once the tower head is on the ground, it and the crossarm are manually dismantled using a crane.

[0199] The rail-mounted heavy-duty AGV transport vehicle used in this embodiment is an important component in the tower dismantling process. Therefore, a safety analysis and rigorous verification of the vehicle's structural strength and load-bearing capacity are still required.

[0200] Static stress analysis of the AGV transport vehicle frame shows that when the mounting surfaces of the drive wheels and follower wheels are fixed and a force of 6t is applied to the clamping compartment, the maximum stress occurs at the side plate of the clamping compartment of the frame, and the maximum displacement occurs at the bottom plate of the clamping compartment of the frame. Therefore, these two areas are reinforced in the design by using high-strength steel plates.

[0201] Simultaneously, a force model is used to calculate the maximum lateral force F that the AGV transport vehicle can withstand:

[0202] In this embodiment, the AGV transport vehicle has a left-side support force N1 of 30000N, a right-side support force N2 of 30000N, and a vehicle weight G of 20000N. Based on the selected torque balance point, the following calculations can be performed:

[0203]

[0204] Therefore, F = 36654N is calculated. If the AGV transport vehicle and the truck are to tip over, a force of 36654N needs to be continuously applied to the rear chassis of the truck. Obviously, such a lateral force F does not exist at the heavy truck assembly site. Therefore, the rail-type heavy-duty AGV transport vehicle in this embodiment is suitable for this solution and there is no risk of tipping over.

[0205] S7. During tower dismantling operations, the tension of the guy wires can be adjusted according to wind protection needs and the tower's tilt. The stronger the wind or the greater the tower's tilt, the tighter the guy wire tension needs to be, ensuring the tower's overall self-balancing ability, reducing the impact of vibration on the guy wires, and preventing tower collapse. The specific calculation process is as follows:

[0206] S71. Calculate the operating tension of the guy wires on the windward and leeward sides under different guy wire prestresses:

[0207]

[0208] In the formula For the dynamic coefficient, Let H be the moment of wind load on the base of the tower, and H be the height of the guy wire point from the ground. The angle between the wind direction and the guy wire. The angle between the guy wire and the ground;

[0209] Calculations using ANSYS finite element analysis software can determine the tension variations on the windward and leeward sides under different prestressing conditions (reference). Figure 6 and Figure 7 ):

[0210] Table 6: Tension variation on the windward and leeward sides under different prestressing wires

[0211]

[0212] Table 7: Displacement of the tower under different guy wire prestressing conditions

[0213]

[0214] S72. As can be seen from Table 6-7, the attitude of the tower can be adjusted by adjusting the tension of the guy wires. When the prestress of the guy wires is kept at a certain tension, the tower can resist the influence of wind load, so that the tower as a whole can achieve self-balance and prevent the tower from falling over.

[0215] It should be stated that the above-described specific embodiments are merely preferred embodiments of the present invention and the technical principles employed. Those skilled in the art should understand that various modifications, equivalent substitutions, and variations can be made to the present invention. However, such variations, as long as they do not depart from the spirit of the present invention, should be within the scope of protection of the present invention. Furthermore, some terminology used in this specification and claims is not limiting, but merely for ease of description.

Claims

1. A method for in-situ dismantling of power transmission towers, characterized in that, Includes the following steps: S1. Calculate the downward pressure on the tower, design the bearing capacity of the gantry frame based on the downward pressure, and determine the burial depth of the ground anchor. S2. Perform a wind load stress analysis on the entire tower and calculate the optimal prestress of the guy wires; S3. The main tower structure is secured with clamping assemblies. The clamping assemblies are connected to the gantry frame via four pulley blocks to form a fixed system for the tower lifting base. The winches are connected to the ground anchors via pull bars and to the clamping assemblies via pulley blocks, enabling the application of tension or release force to the clamping assemblies. The pulley blocks are connected to the gantry frame via tension sensors, which transmit the tension load of each leg of the tower and the load of the entire gantry frame to the control system in real time. The control system then adjusts the working status of each winch in real time. S4. Install acceleration sensors on each of the four legs of the tower. The acceleration sensors transmit the real-time data to the control system. The control system calculates the corresponding tilt angle value and smooths and filters the tilt angle data. At the same time, it quickly determines the winch closest to the highest point of the platform in the current state, calculates the difference in the position of other winches reaching the highest point, and drives the corresponding winch to perform rope winding or unwinding operations so that all the legs of the tower are at the same height. S5. A Bayesian fusion algorithm using a Kalman filter is used to fuse data from multiple sensors to obtain more reliable data information. S6. Divide the tower into multiple sections and dismantle it section by section from bottom to top using the reverse dismantling method. Loosen the anchor bolts of the tower, start all the winches, and slowly pull the tower off the ground. Dismantle the bottom section, use a rail-mounted heavy-duty AGV to pull the section out, and then use a crane to lift the dismantled section out of the construction area. The winches slowly lower the remaining tower, and then move the clamp assembly up one section to hold the remaining main tower material. Repeat the above operation to dismantle the tower. S7. During the tower dismantling operation, the tension of the guy wires is adjusted according to the wind protection requirements and the tower's tilt condition, so that the tower as a whole can achieve self-balance.

2. The method for in-situ dismantling of transmission towers according to claim 1, characterized in that, Step S1 specifically includes: S11. Calculate the downward pressure on the tower: In the formula This is the initial stress of the upper tension wire. This is the initial stress of the lower layer of tension wire. The weight of the tower itself; S12. Calculate the vertical bearing capacity of a single pile of the gantry frame: In the formula Where L is the ultimate lateral resistance, h is the circumference of the circular pile, and h is the soil layer thickness. This is the standard value of the limiting side resistance. This is the soil liquefaction reduction factor; Calculate the total ultimate lateral resistance of a single pile of the gantry crane in each soil layer: Calculate the limiting end resistance: In the formula This is the standard value of the extreme end resistance. This represents the cross-sectional area of ​​the foundation pile; Calculate the design value of total side drag: In the formula This is the partial factor for the vertical bearing capacity resistance of the pile foundation; Calculate the design value of the end resistance: Calculate the design value of the vertical bearing capacity of the foundation pile: In the formula This is the partial factor for the vertical bearing capacity resistance of the pile foundation; S13. Determine the burial depth of the ground anchor: In the formula The soil volume for the pull-out resistance of the ground anchor. For soil density, Let be the safety factor for the pull-out resistance of the ground anchor, 'a' be the angle between the direction of the force on the ground anchor and the ground surface, and 'd' be the width of the ground anchor. Where is the length of the ground anchor, and h is the burial depth of the ground anchor. For soil pull-out angle.

3. The method for in-situ dismantling of transmission towers according to claim 1, characterized in that, Step S2 specifically includes: S21. Calculate the magnitude of the wind load on the tower: In the formula This is the standard value of wind load. Basic wind pressure, This is the wind pressure height variation coefficient. This is the wind load shape coefficient. This is the wind load adjustment factor. The calculated value of the projected area to withstand wind pressure; S22. Calculate the moment at the base of the tower, and obtain the corresponding calculated values ​​according to different wind load combinations: In the formula Let q be the moment of the wind load on the lifting root, q be the wind load of each segment, and h be the height of the center of gravity of each wind load relative to the root of the tower. When calculating the wind load on the tower in segments, This is the algebraic sum of the moments of each wind load on its root. S23. Determine the wind speed corresponding to the wind pressure according to the wind force classification standard; S24. Based on the reference standard for prestressed guy wires and combined with the above stress analysis of the tower, the optimal prestress of the guy wires is determined.

4. The method for in-situ dismantling of transmission towers according to claim 1, characterized in that, The specific calculation process for the tilt angle value in step S4 is as follows: S41. Calculate the roll angle and pitch angle of each tower leg: In the formula The roll angle of the object's posture is the rotation angle around the X-axis. The pitch angle of the object's posture is the rotation angle around the Y-axis. , , These are the triaxial acceleration components measured by the accelerometer; S42. Calculate the tilt angle of the iron tower relative to the natural gravity axis: Convert the above radian values ​​to natural angle values.

5. The method for in-situ dismantling of transmission towers according to claim 4, characterized in that, The specific process of smoothing and filtering the tilt angle data in step S4 is as follows: S43. The accelerometer reads the acceleration values ​​of the three axes at millisecond intervals and calculates the aforementioned angle values ​​in real time to obtain a data sequence of tilt angle values. Then, a Kalman filter is used to iterate through the tilt angle value sequence to predict the tilt angle value. In the formula, X is the predicted value of the state at time k based on the information at time k-1, A is the state transition matrix, and B is the control input matrix. For the control input at time k, initially set A=1 in the formula. =0; S44. Calculate the covariance of the predicted tilt angle: In the formula Let be the covariance matrix of the predicted state at time k. Let Q be the covariance matrix of the optimal state estimate at time k-1, and let Q be the system noise covariance matrix. S45. Update the Kalman coefficients: In the formula Let H be the Kalman gain at time k, H be the observation matrix, and R be the observation noise covariance matrix. Initially, H is set to 1 in the formula. S46. Calculate the current optimal value and the covariance of the optimal value: In the formula Let k be the observation value at time k; S47. After iterating through all the data in the data sequence, the effective tilt angle value after filtering can be obtained.

6. The method for in-situ dismantling of transmission towers according to claim 1, characterized in that, Step S5 specifically includes: S51. Based on the system's dynamic model, use the sensor's state estimate and covariance estimate from the previous moment to predict the sensor's state and covariance at the current moment; when new detection data is obtained, calculate the Kalman gain according to the update equation, and then update the state estimate and covariance estimate. S52. Calculate the weights of each Kalman filter result: In the formula This is the covariance estimate of the Kalman filter at time k; S53. Bayesian fusion using weighted averaging: In the formula These are the estimated states after fusion. This is the estimated value of the fused covariance.

7. The method for in-situ dismantling of transmission towers according to claim 1, characterized in that, Step S7 specifically includes: S71. Calculate the operating tension of the guy wires on the windward and leeward sides under different guy wire prestresses: In the formula For the dynamic coefficient, Let H be the moment of wind load on the base of the tower, and H be the height of the guy wire point from the ground. The angle between the wind direction and the guy wire. The angle between the guy wire and the ground; S72. Adjust the tension of the guy wires according to different guy wire prestresses to adjust the attitude of the tower so that the tower as a whole can achieve self-balance.

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