CN-121977419-A - Method and device for determining length of bored pile of transmission line tower and storage medium

CN121977419ACN 121977419 ACN121977419 ACN 121977419ACN-121977419-A

Abstract

The invention relates to a method and a device for determining the length of a bored pile of a transmission line tower, and a storage medium. The method for determining the length of the bored pile of the transmission line tower comprises the following steps of establishing a coordinate system taking a pile axial direction as a z-axis and taking a horizontal plane as an xOy plane, laying a measuring line in a position parallel to the z-axis and at a preset horizontal distance from the center of the pile, collecting magnetic field data along the measuring line, preprocessing the collected magnetic field data to obtain preprocessed data at least comprising a horizontal component B x and a vertical component B z , extracting a plurality of characteristic positions for judging the length of a reinforcement cage based on the preprocessed data, and calculating the length of the reinforcement cage by utilizing the characteristic positions according to a mapping relation between the preset characteristic positions and the length of the reinforcement cage. The invention improves the accuracy and repeatability of the length estimation and realizes the high-efficiency, nondestructive and high-reliability length detection of the pile foundation of the transmission line tower.

Inventors

LI KAITE
WU KEWEI
CAO YAZHOU
GAO RUNDONG
YANG JIAN
Yu Danyao
LIU JIAYAO
XU XIANGNAN
JIANG YIFENG
TIAN XIAO
YAO GUANSHENG

Assignees

国网电力工程研究院有限公司
国家电网有限公司

Dates

Publication Date: 20260505
Application Date: 20251222

Claims (10)

1. A method for determining the length of a bored pile of a transmission line tower, comprising the steps of: Establishing a coordinate system taking the axial direction of the pile as a z-axis and the horizontal plane as an xOy plane, laying a measuring line along the direction parallel to the z-axis and at a preset horizontal distance from the center of the pile, and collecting magnetic field data along the measuring line; Preprocessing the acquired magnetic field data to obtain preprocessed data at least comprising a horizontal component B x and a vertical component B z ; extracting a plurality of characteristic positions for judging the length of the reinforcement cage based on the preprocessing data; And calculating the length of the reinforcement cage by utilizing the characteristic positions according to the pre-established mapping relation between the characteristic positions and the length of the reinforcement cage.
2. The method of claim 1, wherein the feature locations comprise: A first characteristic position corresponding to a maximum value of the horizontal component B x ; the zero crossing point position of the vertical component B z corresponds to a second characteristic position; And a third characteristic position corresponding to the maximum position of the gradient dB z /dz of the vertical component B z .
3. The method according to claim 2, wherein the calculating the length of the reinforcement cage according to the pre-established mapping relationship between the characteristic position and the length of the reinforcement cage by using the characteristic position specifically includes: Based on the first characteristic position, the second characteristic position and the third characteristic position, calculating to obtain a corresponding length estimated value through respective mapping functions; Calculating uncertainty of each length estimation value; and carrying out weighted fusion on the length estimation value based on the uncertainty of the length estimation value to obtain a final reinforcement cage length estimation value.
4. The method according to claim 1, characterized in that the uncertainty σl, i of the length estimate is obtained by the following calculation formula: Wherein, sigma L,i is uncertainty of the length estimation value; u i , the characteristic position (unit: m) corresponding to the ith criterion, wherein the A criterion takes the peak position coordinate x \* along the axial direction of the pile, the B criterion takes the zero crossing position z 0 of B z , and the C criterion takes the peak position z p of dB z /dz; θ is the calibration/environmental parameter; The first derivative of the mapping function f i with respect to u i at point u i ; Standard deviation/uncertainty (unit: m) of feature location u i ; the uncertainty σ μi of the feature position is obtained by the following calculation formula: In the formula, A i , the peak height of the ith characteristic curve in the neighborhood of the characteristic position; sigma B,i , standard deviation of background noise (consistent with magnetic field unit) of the ith curve in the neighborhood of the characteristic position; c 2,i , performing secondary fitting B (u) approximately equal to the absolute value of a quadratic term coefficient obtained by c 0 +c 2 (u-u \* ) 2 on the neighborhood of the characteristic position of the ith curve; wherein u is the space coordinate argument (unit: m) along the measurement path; b (u) a functional representation of the magnetic field component curve recorded at position u; and c 0 constant term/local baseline in the quadratic fit. And c 2 , quadratic term coefficient in quadratic fitting.
5. The method of claim 1, further comprising the step of anomaly detection and adaptation prior to said weighted fusion of said length estimates based on their uncertainty: Monitoring abnormal indexes of the magnetic field environment in real time, wherein the abnormal indexes at least comprise background magnetic field baseline difference values at two ends of a measuring line and/or energy duty ratio of low-frequency components in a magnetic field signal; and when any abnormal index exceeds a preset threshold, judging that the magnetic field environment is abnormal, increasing uncertainty corresponding to one or more length estimated values affected by the abnormality, and carrying out weighted fusion.
6. The method of claim 1, wherein the preprocessing comprises performing soft/hard iron calibration, attitude compensation, altimetry error correction, and bandpass or adaptive filtering on the magnetic field data.
7. The method according to claim 1, wherein the mapping relationship is obtained by analytical derivation of equivalent magnetized cylindrical models of the reinforcement cage, and by parameter calibration or fitting correction of standard reinforcement cage samples of known length.
8. An apparatus for determining the length of a transmission tower pile foundation reinforcement cage, comprising: The magnetic field acquisition unit is used for acquiring magnetic field data along the z-direction measuring line; the gesture and positioning unit is used for providing gesture information and measuring line position information of the sensor; A processing unit for executing the method of any one of claims 1 to 7 and outputting the reinforcement cage length estimation value and the confidence information; and the display and storage unit is used for presenting and storing the processing result.
9. The apparatus of claim 8, wherein the magnetic field acquisition unit is a single-channel or multi-channel magnetic sensor array, and the sensor is a fluxgate, hall, or atomic magnetometer; the processing unit comprises an abnormality detection module for monitoring the change of the environmental geomagnetism so as to carry out differential correction.
10. A computer readable storage medium having stored thereon an execution program which, when executed, implements the method of any of claims 1 to 7.

Description

Method and device for determining length of bored pile of transmission line tower and storage medium Technical Field The invention belongs to the technical field of electromagnetic measurement, and particularly relates to a method and device for determining the length of a bored pile of a transmission line tower, and a storage medium. Background In the foundation engineering of the transmission line tower, the bored pile is widely applied due to high bearing capacity and good adaptability. The actual embedded length of the reinforcement cage in the pile is a key parameter for measuring the quality of the pile foundation and ensuring the structural safety. The traditional pile length detection method has a plurality of limitations in engineering practice, and is difficult to meet the field detection requirements of high efficiency, non-damage and high reliability. At present, the length detection of a reinforcement cage of a bored pile of a transmission line tower mainly depends on an excavation/core drilling rechecking method, an acoustic method and an electromagnetic method. And (5) excavating/drilling core rechecking, and confirming the end position of the reinforcement cage through construction record, lofting rechecking, partial excavation or drilling core sampling. The core drilling method utilizes the core drilling technology and the operation technology to drill a concrete core sample along the length direction of the pile body. If the rock-soil characteristics of the pile end bearing layer are required to be identified, a rock-soil core sample below the pile end is also required to be drilled. The integrity and length of the pile body can be determined and detected by observing and analyzing the core sample, and the method can also be used for detecting the strength of the concrete of the pile body, the thickness of the sediment at the bottom of the pile and the like. Such methods are destructive and inefficient, costly, and not suitable for large-scale screening. The acoustic type method includes a low strain reflection wave method and a sound wave transmission method. Such methods evaluate pile body integrity and length based on the propagation characteristics of stress waves or sound waves in the pile body. However, it focuses more on identifying defects and concrete property changes, and is less directly indicative of the specific interface "reinforcement cage end" and is susceptible to coupling conditions, pouring interfaces and material differences. After the pile top is connected with the upper structure, the reflected wave signal is easy to interfere, the accuracy of judging the length is reduced, the sound wave transmission rule needs to pre-embed the sound measuring tube, and the detection effect is greatly influenced by the coupling condition and the uniformity of the concrete. The electromagnetic method utilizes a reinforcement cage to detect disturbance of a geomagnetic field, and common methods include a zero crossing method based on a vertical component B z of a geomagnetic background and an electromagnetic induction method of which part needs external excitation. The method has the defects that the magnetic method based on B z and the gradient thereof is easy to have low-frequency drift and inconsistent base line under the interference of hot working remanence, geomagnetic non-uniformity or peripheral temporary steel structure, so that zero crossing point or gradient peak position deviation is caused, and the judging length is unstable. The power transmission engineering field has the characteristics of more metal components, frequent temporary facilities, large environmental change and the like, requires a detection means to be nondestructive and rapid, can stably give the length of the reinforcement cage in a complex magnetic environment, and can provide interpretable confidence information so as to support batch census and repeated measurement of key piles. The existing method based on B z or the gradient thereof is insufficient in stability under abnormal working conditions. In view of the foregoing, a new nondestructive detection method for the length of a bored pile reinforcement cage is needed to solve the problem of insufficient stability in a complex magnetic environment. Disclosure of Invention In order to solve the technical problems, the invention provides a method for determining the length of a bored pile of a transmission line tower, which comprises the following steps: Establishing a coordinate system taking the axial direction of the pile as a z-axis and the horizontal plane as an xOy plane, laying a measuring line along the direction parallel to the z-axis and at a preset horizontal distance from the center of the pile, and collecting magnetic field data along the measuring line; Preprocessing the acquired magnetic field data to obtain preprocessed data at least comprising a horizontal component B x and a vertical component B z; extracting a plurality of characteris