Underground structure outer wall leakage detection method, system and device

Abstract

The invention relates to the technical field of ultrasonic detection, in particular to an underground structure outer wall leakage detection method, system and device, and the method comprises the steps: analyzing the disorder condition of the ultrasonic waveform of a detection point of an underground structure outer wall, and obtaining the steel bar region possibility of the detection point; screening to obtain a target detection point according to the possible symmetry condition of the transverse and longitudinal steel bar areas in the local range of the detection point; according to the steel bar area possibility of each detection point in the target range of the target detection point and the ultrasonic amplitude of each detection point at each moment, the standard amplitude of each moment in the steel bar standard waveform is obtained, the steel bar standard waveform is removed from the ultrasonic waveform, an abnormal signal waveform is obtained, and leakage detection is carried out on the underground structure outer wall. According to the method, feature modeling is carried out on the interference of the reinforcing steel bars and the reinforcing steel bars are eliminated, obstacles are cleared away for underground structure outer wall leakage detection, and therefore the underground structure outer wall leakage detection precision and reliability are improved.

Description

Technical Field

[0001] This invention relates to the field of ultrasonic testing technology, specifically to a method, system, and device for detecting leakage in the exterior walls of underground structures. Background Technology

[0002] Underground structures refer to man-made structures built below the earth's surface that serve functions such as load-bearing, enclosure, and space utilization. They encompass types such as building basements, underground parking garages, subway tunnels, underground utility tunnels, foundation pit support structures, and hydraulic tunnels. Among these, the exterior walls of underground structures act as a crucial barrier to isolate groundwater from the internal space. Groundwater infiltration can lead to steel corrosion, accelerated concrete carbonization, weakened structural load-bearing capacity, and even safety hazards such as crack propagation and wall spalling. Therefore, leak detection of the exterior walls of underground structures is extremely important.

[0003] The commonly used detection method is ultrasonic testing. Ultrasonic testing is performed on the exterior walls of underground structures, and the waveform characteristics of the received ultrasonic waves are analyzed. The leakage status of the wall is determined through waveform analysis: When the wall structure is intact and leak-free, the ultrasonic waveform only presents the initial wave and the normal interface wave, with sharp and clear peaks, stable peak spacing, and no extraneous noise between the initial wave and the interface wave. The overall waveform is regular and without abnormal disturbances. If there are leakage channels in the wall, the accumulated water at the leakage point will change the acoustic properties of the medium, and the crack interface will also cause sound wave scattering and reflection disorder. In this case, irregular additional amplitude peaks will appear between the initial wave and the interface wave—these extraneous peaks have chaotic shapes, obvious amplitude fluctuations, and unpredictable peak spacing.

[0004] Because the exterior walls of underground structures are typically made of reinforced concrete (with main bars and stirrups arranged in a dense steel mesh), ultrasonic waves encountering rigid media like steel reinforcement during propagation experience strong reflection and scattering, directly disrupting the continuity of sound wave propagation. The reflected signals from the steel reinforcement create numerous additional peaks in the received ultrasonic waveform—non-initial waves and abnormal interface waves. These peaks are often periodic (matching the spacing of the steel reinforcement) and have significantly higher amplitudes than the leakage defect signals. They not only obscure the clear outlines of the initial and interface waves but also superimpose with the clutter from the leakage defects, making it difficult to distinguish between the steel reinforcement reflection signals and the leakage defect signals, thus affecting the detection accuracy of leaks in the exterior walls of underground structures. Summary of the Invention

[0005] To address the technical problem that interference from reflected signals from reinforcing steel bars affects the detection accuracy of leaks in the exterior walls of underground structures, the present invention aims to provide a method, system, and device for detecting leaks in the exterior walls of underground structures. The specific technical solution adopted is as follows: In a first aspect of the present invention, a method for detecting leakage in the exterior walls of underground structures is provided, comprising: By analyzing the chaotic ultrasonic waveforms at the detection points of the underground structure's exterior wall, the probability of the steel reinforcement area at the detection points can be obtained. Based on the symmetry of the possible transverse and longitudinal reinforcement areas within the local area of ​​the detection point, the reference value of the detection point for participating in the acquisition of the standard waveform of the reinforcement is determined. The target detection points are selected based on the reference value of each detection point; The standard amplitude of the standard waveform of the steel reinforcement at each moment is obtained from the probability of the steel reinforcement area at each detection point within the target range of the target detection point and the ultrasonic amplitude at each detection point at each moment. The standard waveform of the steel bar is removed from the ultrasonic waveform to obtain the abnormal signal waveform; Based on the abnormal signal waveform, leakage detection is performed on the exterior walls of the underground structure.

[0006] In an exemplary embodiment, the process of obtaining the probability of the reinforcing steel area includes: Select several peaks from the maxima in the ultrasonic waveform; The peak intensity is obtained from the average amplitude of the peak. The degree of fluctuation in the peak time interval is obtained from the time interval between adjacent peaks; The probability of the rebar region is obtained from the peak intensity, the fluctuation degree of the peak time interval, and the number of peaks; the probability of the rebar region is positively correlated with the peak intensity and the number of peaks, and negatively correlated with the fluctuation degree of the peak time interval.

[0007] In one exemplary embodiment, the reference acquisition process includes: The probability difference of the rebar region for each pair of symmetrical points in the horizontal direction with the detection point as the center is obtained to obtain the horizontal symmetry feature; the pair of symmetrical points includes two other detection points that have a positional symmetry relationship with the detection point as the center; the horizontal symmetry feature is inversely correlated with the probability difference of the rebar region for each pair of symmetrical points in the horizontal direction. The longitudinal symmetry feature is obtained by acquiring the probability difference of the rebar region for each pair of symmetrical points in the longitudinal direction centered on the detection point; the longitudinal symmetry feature is inversely correlated with the probability difference of the rebar region for each pair of symmetrical points in the longitudinal direction. The reference is obtained by integrating the horizontal symmetry features and the vertical symmetry features.

[0008] In an exemplary embodiment, the step of selecting target detection points based on the reference value of each detection point includes: The reference value of each detection point is determined and the value of the preset reference value threshold is determined. If there is a detection point with a reference value greater than the preset reference value threshold, the detection point with the highest reference value is selected as the target detection point.

[0009] In one exemplary embodiment, the process of obtaining the standard amplitude includes: The influence weight of each detection point is obtained from the probability of the rebar area at each detection point within the target range of the target detection point; the influence weight is positively correlated with the probability of the rebar area. Based on the influence weight of each detection point, the ultrasonic amplitude of each detection point at any time is weighted and summed to obtain the standard amplitude of the steel reinforcement standard waveform at any time. Accordingly, the standard waveform of the reinforcing bar is composed of the standard amplitude at each moment.

[0010] In an exemplary embodiment, the process of acquiring the abnormal signal waveform includes: Time alignment is performed between the ultrasonic waveform and the standard waveform of the reinforcing bar. The abnormal signal waveform is obtained by subtracting the standard waveform of the steel bar from the time-aligned ultrasonic waveform.

[0011] In an exemplary embodiment, the step of detecting leakage in the exterior wall of the underground structure based on the abnormal signal waveform includes: Obtain the peak amplitude difference sequence of the abnormal signal waveform at the test point, wherein the peak amplitude difference sequence is composed of the amplitude difference between two adjacent peaks in the abnormal signal waveform; The amplitude difference fluctuation degree of the peak amplitude difference sequence is determined to obtain the initial probability of leakage of the underground structure exterior wall at the test point.

[0012] In an exemplary embodiment, after obtaining the initial probability of leakage in the underground structure's exterior wall at the test point, the method for detecting leakage in the underground structure's exterior wall further includes: Obtain the similarity of the abnormal signal waveforms between the detection point to be tested and its neighboring detection points; Based on the similarity of the abnormal signal waveform and the initial probability of leakage in the underground structure's exterior wall, the final probability of leakage in the underground structure's exterior wall at the test point is obtained; the final probability of leakage in the underground structure's exterior wall is positively correlated with both the similarity of the abnormal signal waveform and the initial probability of leakage in the underground structure's exterior wall.

[0013] In a second aspect of the present invention, an underground structure exterior wall leakage detection system is provided, comprising: a memory and a processor; the memory is connected to the processor; the memory is used to store program instructions; the processor is used to implement the above-described underground structure exterior wall leakage detection method when the program instructions are executed.

[0014] In a third aspect of the invention, an underground structure exterior wall leakage detection device is provided, comprising a computer-readable storage medium storing a computer program that, when executed by a processor, implements the steps in the above-described underground structure exterior wall leakage detection method.

[0015] This invention offers the following advantages: First, it identifies the potential reinforcing steel region at the detection point based on the clutter of the ultrasonic waveform, thus pinpointing the potential influence area of ​​this interference source. Then, it innovatively proposes evaluating the reference value of the detection point signal based on the potential lateral and longitudinal symmetry of the reinforcing steel reflection signal within a local area (derived from the regular geometric arrangement of the reinforcing steel mesh). This step is crucial; it utilizes the essential difference in spatial distribution patterns between the reinforcing steel reflection signal and leakage clutter to select the target detection point that best represents typical reinforcing steel reflection. Based on this target detection point, a standard reinforcing steel waveform is constructed, achieving the extraction and quantification of a standard signal model for the reinforcing steel from the mixed signal. This allows the standard reinforcing steel waveform to be removed from the original waveform, resulting in an abnormal signal waveform, avoiding interference from the standard reinforcing steel waveform. Finally, the purified abnormal signal waveform is used for underground structure external wall leakage detection. This invention, by modeling and eliminating the interference from reinforcing steel, removes obstacles to underground structure external wall leakage detection, thereby improving the detection accuracy and reliability. Attached Figure Description

[0016] Figure 1 This is a flowchart of the steps of a method for detecting leakage in the exterior wall of an underground structure according to an embodiment of the present invention; Figure 2 This is a schematic diagram of an ultrasonic waveform provided in one embodiment of the present invention; Figure 3 This is a reference flowchart provided in one embodiment of the present invention; Figure 4 This is a flowchart of the standard amplitude acquisition process provided in one embodiment of the present invention. Detailed Implementation

[0017] To further illustrate the technical means and effects adopted by the present invention to achieve its intended purpose, the specific implementation methods, structures, features, and effects of the present invention are described in detail below with reference to the accompanying drawings and preferred embodiments. In the following description, different "one embodiment" or "another embodiment" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics in one or more embodiments can be combined in any suitable form.

[0018] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. All data and information collected in this application have been obtained with full consent.

[0019] This embodiment provides a method for detecting leakage in the exterior walls of underground structures, which is used to detect groundwater infiltration in the exterior walls of underground structures and achieve leakage detection in the exterior walls of underground structures.

[0020] like Figure 1 As shown in the figure, the method for detecting leakage in the exterior wall of an underground structure provided in this embodiment includes the following steps: Step S1: Analyze the chaotic state of the ultrasonic waveform at the detection point of the underground structure's outer wall to obtain the probability of the steel reinforcement area at the detection point; Step S2: Based on the possible symmetry of the transverse and longitudinal reinforcement areas within the local area of ​​the detection point, determine the reference value of the detection point for participating in the acquisition of the standard waveform of the reinforcement. Step S3: Based on the reference value of each detection point, select the target detection points; Step S4: Based on the probability of the rebar area at each detection point within the target range of the target detection point, and the ultrasonic amplitude at each detection point at each moment, obtain the standard amplitude of the rebar standard waveform at each moment. Step S5: Remove the standard waveform of the steel bar from the ultrasonic waveform to obtain the abnormal signal waveform; Step S6: Based on the abnormal signal waveform, conduct leakage detection on the exterior wall of the underground structure.

[0021] The following detailed explanation of each step, in conjunction with the accompanying drawings, is provided.

[0022] Step S1: Analyze the chaotic state of the ultrasonic waveform at the detection point of the underground structure's outer wall to obtain the probability of the reinforcing steel area at the detection point.

[0023] In this embodiment, for the underground structural exterior wall requiring leakage detection, a rectangle of the underground structural exterior wall is taken as an example. The length and width of the rectangle are used as the horizontal and vertical axes of a two-dimensional plane coordinate system, respectively, and the underground structural exterior wall is mapped onto this two-dimensional plane coordinate system. Multiple detection points are preset on the underground structural exterior wall for ultrasonic testing. The layout of the detection points is set according to actual needs. In an exemplary embodiment, the underground structural exterior wall is gridded with a preset grid size, and the intersection of each grid is a detection point. The grid size is set according to actual needs; in this embodiment, it is set to 5cm × 5cm. This detection point spacing is defined as coarse scanning, used to distinguish it from fine scanning as described later.

[0024] Connect the ultrasonic transducer to the main unit, calibrate the equipment's transmission power and gain parameters to ensure stable ultrasonic signal output; apply high-viscosity coupling agent to the transducer probe to eliminate air interference. Hold the transducer vertically against the detection point, apply uniform pressure, keep the probe firmly attached to the wall without slipping, and scan each detection point one by one. The main unit automatically stores the ultrasonic waveform acquired at each detection point.

[0025] Taking any detection point as an example, obtain the ultrasonic waveform of that detection point within a preset time period, such as... Figure 2 As shown, the horizontal axis represents time, in microseconds, and the vertical axis represents the ultrasonic amplitude, in volts, essentially the voltage intensity of the received ultrasonic signal. Because building materials such as concrete severely attenuate high-frequency ultrasonic waves, lower-frequency ultrasonic waves are typically used for penetration testing. The center frequency is generally between 20 kHz and 200 kHz, with further commonly used frequencies around 50 kHz to 100 kHz. To ensure signal quality, in engineering practice, a sampling frequency of 4 to 10 times the signal center frequency is usually chosen. Taking a center frequency of 50 kHz as an example, according to the 4-10 rule, the ultrasonic sampling frequency should be between 200 kHz and 500 kHz. The specific value is set according to the actual situation. The duration of the preset time period is set according to actual needs, usually between 1 millisecond and 2 milliseconds. For thicker walls or situations requiring observation of later attenuation, it may be necessary to extend it to 5 milliseconds or longer.

[0026] Analyzing the chaotic nature of the ultrasonic waveform at the detection point helps determine its likelihood of being located in a rebar-affected area. The rebar in the underground structure's exterior wall is arranged regularly with equal spacing according to design specifications (main reinforcement spacing is typically 10–20 cm). When ultrasonic waves propagate through concrete, they encounter rigid metallic media like rebar, resulting in strong reflections due to abrupt changes in acoustic impedance (rebar impedance is approximately 5 times that of concrete), forming high-amplitude signals. Since the rebar spacing is fixed, the time difference between the sound wave and adjacent rebars is constant, reflected in the waveform as equally spaced spikes. This characteristic differs significantly from the ultrasonic waveform in areas without rebar, which only contain initial and interface waves. To ensure the scanning density covers the rebar distribution characteristics and avoid missing rebar reflection signals due to excessively large step sizes, a coarse scan of the entire underground structure's exterior wall is performed with a step size of 5 cm. As described above, if the ultrasonic waveform at the detection point exhibits equally spaced high-amplitude spikes, it can be preliminarily determined that the detection point is highly likely to belong to a rebar-affected area. In an exemplary embodiment, the maximum values ​​of the ultrasonic waveform at the detection point are obtained, and then several peaks are selected from these maximum values. The peaks are the maximum values ​​with higher peak values. As an example, a noise threshold value is preset. The principle for setting the noise threshold value is that it is higher than the general maximum value. The noise threshold value can be obtained by: performing ultrasonic testing on a wall of the same type without steel reinforcement in a laboratory to obtain an experimental ultrasonic waveform, obtaining the maximum value among the maximum values ​​in the experimental ultrasonic waveform, and then, in order to improve reliability, the noise threshold value can be 1.5 times the maximum value among the maximum values ​​in the experimental ultrasonic waveform; or, obtaining the average amplitude of each maximum value in the ultrasonic waveform at the detection point, and then, the noise threshold value can be the average amplitude value of a preset multiple, such as 2 times.

[0027] By comparing the magnitudes of each maxima in the ultrasonic waveform at the detection point with a noise threshold, the maxima exceeding the noise threshold are identified as spikes, thus obtaining the individual spikes in the ultrasonic waveform at the detection point and determining the number of spikes. In an exemplary embodiment, the number of maxima in the ultrasonic waveform at the detection point is obtained, and the ratio of the number of spikes to the number of maxima is calculated to normalize the number of spikes and eliminate the influence of dimensions. If there is rebar at the detection point, there should be a sufficient number of spikes in the ultrasonic waveform to ensure the statistical significance of the analysis. Therefore, the larger the normalized number of spikes, the higher the probability of a rebar area at the detection point; the two are positively correlated.

[0028] The average amplitude of each peak is calculated, and the peak intensity is obtained from this average amplitude. A higher average amplitude corresponds to a higher peak intensity; the two are positively correlated. In an exemplary embodiment, the amplitude of the largest peak (i.e., the maximum value in the ultrasonic waveform at that detection point) is obtained, and the ratio of the average amplitude to this maximum value is calculated. This ratio is the peak intensity, thus normalizing the average amplitude and eliminating dimensionality. Since reinforcing steel, as a rigid medium, causes abrupt changes in acoustic impedance, it typically generates high-intensity reflected signals. Therefore, a higher peak intensity indicates a higher likelihood of a reinforcing steel region at the detection point, and the two are positively correlated. The peak intensity, combined with the number of peaks, considers both peak intensity and peak density, forming a composite index.

[0029] The timing of each peak in the ultrasonic waveform at the detection point is determined, thereby obtaining the time interval between each pair of adjacent peaks. The fluctuation degree of the peak time interval is obtained from the time interval between each pair of adjacent peaks. In an exemplary embodiment, the standard deviation is used to characterize the fluctuation degree. To ensure the standard deviation is within the range of 0-1 and dimensionless, facilitating subsequent data processing, this embodiment obtains the maximum time interval among all the time intervals between pairs of adjacent peaks. The ratio of the time interval between each pair of adjacent peaks to this maximum time interval is calculated, thus normalizing the time interval between each pair of adjacent peaks and eliminating the influence of dimensions. Then, the standard deviation of the time intervals between all the normalized pairs of adjacent peaks is calculated, and the result is the fluctuation degree of the peak time interval. Since the reinforcing bars are arranged at equal intervals according to design specifications, each peak should exhibit a highly regular time interval, resulting in a smaller calculated fluctuation degree of the peak time interval. Therefore, the smaller the fluctuation degree of the peak time interval, the more likely the detection point corresponds to a reinforcing bar area, and the higher the probability of the detection point being a reinforcing bar area; the two are inversely correlated.

[0030] Therefore, based on the peak intensity, peak time interval fluctuation, and number of peaks at the detection point, the probability of the rebar area at the detection point can be obtained. Based on the logical analysis above, a specific calculation method for the probability of the rebar area is given below: ; in, This indicates the probability of the rebar area at the A-th detection point. This represents the number of normalized spikes at the A-th detection point. This represents the peak intensity of the spike at the A-th detection point. This represents the fluctuation degree of the peak time interval at the Ath detection point. The three parameters are averaged and then analyzed together to obtain the probability of a rebar region at the detection point. The above calculation method for the probability of a rebar region requires a high peak strength and a relatively regular peak time interval, i.e., the characteristic of "peaks with equal time intervals".

[0031] In this embodiment, if the number of spikes at the detection point is too small, such as less than 3, the probability of the detection point being a rebar area is very small, and the probability of the detection point being a rebar area can be directly determined to be 0.

[0032] It should be noted that in this embodiment, when performing fractional operations, if the denominator is zero or a foreseeable minimum value occurs, resulting in meaningless calculation results or overflow, a very small positive constant is added to the denominator to avoid calculation interruption in order to ensure the stability of the calculation. Furthermore, if the prerequisites (such as the number of maxima or peaks) required to calculate a certain feature (such as the probability of a rebar area, influence weight, etc.) do not meet the minimum requirements (e.g., the number is zero), the calculation result of that feature is directly set to zero or the minimum value, indicating that it has no valid information or its contribution is zero.

[0033] Step S2: Based on the symmetry of the possible transverse and longitudinal reinforcement areas within the local area of ​​the detection point, determine the reference value of the detection point for participating in the acquisition of the standard waveform of the reinforcement.

[0034] The reinforcing bars (main bars and stirrups) of the underground structure's exterior walls are arranged according to a standardized design module (e.g., spacing of 15cm and 20cm, symmetrically distributed in a grid pattern). If a certain detection point exhibits symmetry in the possible reinforcement areas along both the horizontal and vertical axes (i.e., transverse and longitudinal) of the two-dimensional plane coordinate system of the underground structure's exterior walls, it indicates that the reinforcement arrangement at that detection point is free from offset or deformation, accurately representing the standard signal reflected by the reinforcement. This avoids the introduction of noise due to local structural anomalies, providing a foundation for constructing a reliable reinforcement acoustic wave model (i.e., the standard waveform of the reinforcement). Conversely, if the possibility of reinforcement areas along the horizontal and vertical axes at that detection point is asymmetrical, there may be reinforcement misalignment, missing reinforcement, or local structural defects (such as cracks or holes). The waveform will be mixed with abnormal signals and cannot be used as a modeling reference for the reinforcement acoustic wave model. Therefore, for any detection point, the symmetry of the possible reinforcement areas along the horizontal and longitudinal axes within the local area of ​​the detection point determines its reference value for participating in the acquisition of the standard waveform of the reinforcement. In an exemplary embodiment, such as... Figure 3 As shown, the following is a specific acquisition process for reference: Step S21: Obtain the probability difference of the rebar area for each pair of symmetrical points in the horizontal direction with the detection point as the center, and obtain the horizontal symmetry feature.

[0035] For the A-th detection point, a local region centered on the A-th detection point is defined. Within this local region, centered on the A-th detection point, there are several detection points in the horizontal direction (i.e., the horizontal axis direction of the two-dimensional plane coordinate system of the underground structure's outer wall). Since symmetrical point pairs need to be constructed, the number of detection points in the horizontal direction within the local region centered on the A-th detection point is 2I+1. Therefore, centered on the A-th detection point, the left and right sides of the A-th detection point each contain I detection points. The Ai-th and A+i-th detection points in the horizontal direction are two other detection points centered on the A-th detection point and have a positional symmetrical relationship. This results in I pairs of symmetrical points in the horizontal direction. The value of I is set according to actual needs. Since the coarse sweep step length of the detection point is 5cm and the spacing of the main reinforcement bars is usually 10-20cm, I can be set to 20 / 5=4.

[0036] However, for edge detection points that are less than the preset range from the wall boundary (for example, the number of detection points to the left or right of the detection point is less than I), their reference value is not calculated because they cannot form a complete symmetrical point pair, or their reference value is directly set to 0, so that they do not participate in the subsequent selection of target detection points.

[0037] For any pair of symmetrical points in the horizontal direction, taking the Ai-th detection point and the (A+i-th)-th detection point as an example, the difference between the rebar region probability of the Ai-th detection point and the rebar region probability of the (A+i-th)-th detection point is calculated. Specifically, the difference is the absolute value of the difference in rebar region probability, which is taken as the rebar region probability difference of that symmetrical point pair. Thus, the rebar region probability difference of each of the I symmetrical point pairs in the horizontal direction is obtained. The smaller the rebar region probability difference, the stronger the symmetricality of the rebar region probability in the horizontal direction, and the stronger the horizontal symmetry feature of the A-th detection point. Therefore, the horizontal symmetry feature of the A-th detection point is inversely correlated with the rebar region probability difference of each symmetrical point pair in the horizontal direction. In an exemplary embodiment, the following is a method for calculating the horizontal symmetry feature of the A-th detection point: ; in, This represents the lateral symmetry feature of the A-th detection point. This indicates the probability of the rebar region at the Ai-th detection point in the horizontal direction. This represents the probability of the rebar area at the (A+i)th detection point in the horizontal direction. This represents the difference in the probability of the rebar area between the Ai-th detection point and the A+i-th detection point in the horizontal direction, and I represents the number of symmetrical point pairs in the horizontal direction.

[0038] Step S22: Obtain the probability difference of the rebar area for each pair of symmetrical points in the longitudinal direction with the detection point as the center, and obtain the longitudinal symmetry feature.

[0039] Similar to step S21, with the A-th detection point as the center, there are several detection points along the longitudinal direction (i.e., the vertical axis of the two-dimensional plane coordinate system of the underground structure's outer wall). Since symmetrical point pairs need to be constructed, the number of detection points along the longitudinal direction in the local area is 2J+1. Therefore, with the A-th detection point as the center, both the upper and lower sides of the A-th detection point contain J detection points. The Aj-th and A+j-th detection points along the longitudinal direction are two other detection points that are symmetrically positioned with the A-th detection point as the center. This results in J pairs of symmetrical points along the vertical axis. The value of J is set according to actual needs; it can be equal to or different from I. In this embodiment, I is equal to J.

[0040] For any pair of symmetrical points along the longitudinal direction, taking the Aj-th detection point and the A+j-th detection point as an example, the difference between the rebar region probability of the Aj-th detection point and the rebar region probability of the A+j-th detection point is calculated. Specifically, the difference is the absolute value of the difference in rebar region probability, which is taken as the rebar region probability difference for that pair of symmetrical points. This yields the rebar region probability difference for each of the J pairs of symmetrical points along the longitudinal direction. The smaller the rebar region probability difference, the stronger the longitudinal symmetry of the rebar region probability, and thus the stronger the longitudinal symmetry feature of the A-th detection point. Therefore, the longitudinal symmetry feature of the A-th detection point is inversely correlated with the rebar region probability difference of each pair of symmetrical points along the longitudinal direction. In an exemplary embodiment, the following is a method for calculating the longitudinal symmetry feature of the A-th detection point: ; in, This indicates the longitudinal symmetry feature of the A-th detection point. This indicates the probability of the rebar area at the Aj-th detection point in the longitudinal direction. This indicates the probability of the rebar area at the (A+j)th detection point in the longitudinal direction. J represents the difference in the probability of the rebar area between the Aj-th detection point and the A+j-th detection point in the longitudinal direction, and J represents the number of longitudinally symmetrical points.

[0041] Step S23: Integrate the horizontal symmetry features and the vertical symmetry features to obtain a reference.

[0042] The lateral and longitudinal symmetry features of the A-th detection point are integrated. Specifically, the average value of the lateral and longitudinal symmetry features of the A-th detection point is calculated, and the result is used as a reference for the A-th detection point in obtaining the standard waveform of the reinforcing steel bar. .

[0043] Step S3: Based on the reference value of each detection point, the target detection point is selected.

[0044] Step S2 obtains the reference value of each detection point for participating in the acquisition of the standard waveform of the rebar. The higher the reference value, the more likely it is to participate in the acquisition of the standard waveform of the rebar. Therefore, it is necessary to select target detection points from among the detection points based on their reference values. In an exemplary embodiment, this embodiment presets a reference value threshold. This preset reference value threshold is used to compare with the reference values ​​of each detection point, thereby obtaining reference values ​​greater than the preset reference value threshold. Reference values ​​greater than the preset reference value threshold indicate higher reference value and a certain probability of being used as target detection points. The numerical range of this preset reference value threshold is 0-1, and the specific value is set according to the actual judgment needs, such as 0.8.

[0045] The reference value of each detection point is compared with the preset reference value threshold. If there is a detection point with a reference value greater than the preset reference value threshold, the detection point with the highest reference value is determined from these points and used as the target detection point. It should be understood that if the reference value of all detection points is less than or equal to the preset reference value threshold, then none of the detection points can be used as target detection points, none can participate in obtaining the standard waveform of the reinforcing steel, and none of the detection points meet the requirements. In this case, the subsequent steps of the underground structure exterior wall leakage detection method provided in this embodiment will not be executed, all current detection points will be discarded, and detection points in other areas of the underground structure exterior wall will be reselected for detection, or the method will be terminated directly.

[0046] It should be noted that the specific values ​​of the preset thresholds (such as noise threshold, reference threshold, leakage threshold, etc.), coefficients, multiples, or ranges (such as local area size, target area size, etc.) involved in this embodiment are illustrative and not the sole limitation of the present invention. In practical engineering applications, those skilled in the art can determine or adaptively adjust these parameters based on the specific design parameters of the underground structure exterior wall to be tested (such as wall material, thickness, steel reinforcement design specifications, etc.), the performance of the testing equipment used, and the calibration data collected on-site, through conventional experimental calibration, statistical analysis, or optimization algorithms, to achieve the best testing results.

[0047] In addition, if there are at least two maximum reference detection points, then any one of them can be selected as the target detection point, or the detection point with the highest probability of the rebar area can be selected from the maximum reference detection points as the target detection point.

[0048] Step S4: Based on the probability of the rebar area at each detection point within the target range of the target detection point, and the ultrasonic amplitude at each detection point at each moment, obtain the standard amplitude of the rebar standard waveform at each moment.

[0049] After obtaining the target detection point, a square area is determined with the target detection point as the center, which is the target range of the target detection point. Since the spacing of the main bars of the steel bars is usually 10-20cm, the distance between the target detection point and the four sides of the square area is 5cm, that is, the side length of the square area is 10cm.

[0050] In this embodiment, to improve detection accuracy, the scanning step size of each detection point within the target range of the target detection point is set to be smaller, thus making each detection point within the target range a fine-scanning point. In an exemplary embodiment, the scanning step size of each detection point within the target range of the target detection point is 1cm, scanning in a "point-by-point progressive" manner. Following the process provided above, the probability of the rebar region at each detection point within the target range of the target detection point is obtained, and based on the ultrasonic waveform of each detection point within the target range of the target detection point, the ultrasonic amplitude at each moment in the ultrasonic waveform of each detection point is obtained, thereby obtaining the standard amplitude at each moment in the standard waveform of the rebar. It should be understood that the probability of the rebar region at different detection points within the target range of the target detection point may be different, and the ultrasonic waveforms at different detection points may also have certain differences. For any given moment, such as Figure 4 As shown, the following is a specific process for obtaining the standard amplitude at any given time: Step S41: Obtain the influence weight of each detection point from the probability of the rebar area of ​​each detection point within the target range of the target detection point.

[0051] For any detection point within the target detection range (including the target detection point itself), the higher the likelihood of a rebar region at that detection point, the higher the reliability of its ultrasonic waveform, the higher the importance of the ultrasonic amplitude at any given moment in that waveform, and consequently, the higher its influence weight. Conversely, the lower the likelihood of a rebar region at that detection point, the lower the reliability of its ultrasonic waveform, the lower the importance of the ultrasonic amplitude at any given moment in that waveform, and consequently, the lower its influence weight. The influence weight is positively correlated with the likelihood of a rebar region. This allows high-reliability ultrasonic waveforms to dominate the calculation of the standard amplitude, while weakening the interference of low-reliability ultrasonic waveforms. This enables the extraction of common characteristics of rebar reflection (equally spaced spikes, stable amplitude, fixed acoustic time), preventing a single anomalous ultrasonic waveform from lowering the accuracy of the standard rebar waveform.

[0052] In an exemplary embodiment, the sum of the rebar area probabilities of all detection points within the target range of the target detection point is obtained. Then, the ratio of the rebar area probabilities of each detection point within the target range of the target detection point to the sum is calculated, and the result is used as the influence weight of each detection point within the target range of the target detection point.

[0053] It should be understood that the probability of the rebar area at all test points within the target range of the target test point cannot be 0 simultaneously; that is, the sum of the probabilities of the rebar area at all test points within the target range of the target test point cannot be 0. In extreme cases, if this sum is 0, it indicates that the selected target test point does not meet the requirements. In this case, the target test point is discarded, and subsequent steps are not performed. Test points in other areas of the underground structure's exterior wall are selected for testing, or the method is terminated directly.

[0054] Step S42: Based on the influence weight of each detection point, the ultrasonic amplitude of each detection point at any time is weighted and summed to obtain the standard amplitude of the standard waveform of the steel reinforcement at any time.

[0055] It should be understood that this embodiment requires time alignment of the ultrasonic waveforms when processing data between different ultrasonic waveforms. For example, here: since it is necessary to obtain the ultrasonic amplitude at the same moment in the ultrasonic waveforms of multiple detection points, it is necessary to perform time alignment of the ultrasonic waveforms of each detection point within the target range of the target detection point. For example: using the ultrasonic waveform of the target detection point as a reference, the time shift of the ultrasonic waveforms of other detection points within the target range of the target detection point is calculated using a cross-correlation algorithm, and then the time axis alignment processing is performed on the ultrasonic waveforms of other detection points within the target range of the target detection point to ensure that the ultrasonic waveforms of each detection point within the target range of the target detection point are time aligned.

[0056] Taking time t as an example, obtain the ultrasonic amplitude at time t in the ultrasonic waveform of each detection point within the target range of the target detection point. Then, based on the influence weight of each detection point within the target range of the target detection point, perform a weighted summation of the ultrasonic amplitudes at time t in the ultrasonic waveform of each detection point within the target range of the target detection point to obtain the standard amplitude of the standard waveform of the rebar at time t. The standard amplitudes at other times are processed in the same way to obtain the standard amplitude at each time, as shown in the calculation formula below: ; in, This represents the standard amplitude at time t in the standard waveform of the reinforcing bar. This represents the influence weight of the r-th detection point within the target range of the target detection point. This represents the ultrasonic amplitude at time t in the ultrasonic waveform of the r-th detection point within the target range of the target detection point. This indicates the number of detection points within the target area of ​​the target detection point.

[0057] After obtaining the standard amplitude at each moment in the standard waveform of the reinforcing steel, the standard waveform of the reinforcing steel can be constructed based on the standard amplitude at each moment in the standard waveform of the reinforcing steel. The standard waveform of the reinforcing steel (including the reflection characteristics of concrete) accurately contains all the characteristics of the reflection of the reinforcing steel (periodic peak position, amplitude, frequency).

[0058] Step S5: Remove the standard waveform of the steel bar from the ultrasonic waveform to obtain the abnormal signal waveform.

[0059] Since the ultrasonic waveform at the detection point is a superposition of the reflected signal from the rebar and the signal of potential leakage defects, after obtaining the standard waveform of the rebar, the standard waveform can be removed from the ultrasonic waveform at the detection point to obtain the abnormal signal waveform. The abnormal signal waveform can completely eliminate the interference from the rebar, highlighting the abnormal information related to leakage and achieving effective signal separation.

[0060] The test point can be any point. The standard waveform of the reinforcing steel bar is removed from the ultrasonic waveform of the test point to obtain the abnormal signal waveform of the test point.

[0061] It should be understood that before removing the standard waveform of the rebar, the ultrasonic waveform of the test point needs to be time-aligned with the standard waveform of the rebar. In an exemplary embodiment, the rising edge of the initial wave in the standard rebar waveform is taken as the time zero point. The ultrasonic waveform of the test point is calibrated by time axis translation. For example, if the initial wave of the ultrasonic waveform of the test point is delayed by 0.2 μs, the entire waveform is shifted to the left by 0.2 μs to ensure that the initial wave of the ultrasonic waveform of the test point completely coincides with the position of the standard rebar waveform, thus eliminating the influence of the transducer trigger time difference. It should be understood that this embodiment can also select other existing time alignment methods as needed.

[0062] The abnormal signal waveform of the test point is obtained by subtracting the standard rebar waveform from the time-aligned ultrasonic waveform. The rebar reflection signals that perfectly match will cancel each other out (difference = 0), retaining only the mismatched abnormal signals (such as noise or amplitude abrupt changes caused by leakage). Since the reflection signals from leakage defects are irregular and cannot be canceled out by the standard rebar waveform, the abnormal signal waveform obtained after differentiation can completely eliminate rebar interference, highlighting leakage-related abnormal information and achieving effective signal separation.

[0063] The ultrasonic amplitude at time t in the abnormal signal waveform of the detection point is calculated as follows: ; in, This represents the ultrasonic amplitude at time t in the abnormal signal waveform of the detection point. This represents the ultrasonic amplitude at time t in the ultrasonic waveform of the test point. This represents the standard amplitude at time t in the standard waveform of the reinforcing bar. Indicates to Find the absolute value.

[0064] Step S6: Based on the abnormal signal waveform, conduct leakage detection on the exterior wall of the underground structure.

[0065] Based on the abnormal signal waveforms at the test points, leakage detection is performed on the underground structural exterior walls at those points. The abnormal signal waveforms have had their regular signals from the reinforcing steel removed. The baseline of the abnormal signal waveforms should be stable (containing only weak concrete background noise). If the abnormal signal waveforms exhibit chaotic spikes, it indicates the presence of irregular reflection interfaces in the sound wave propagation path (such as the rough surface of a leakage crack or abrupt changes in the medium in a waterlogged area). If abrupt changes in amplitude occur in the abnormal signal waveforms, it stems from increased sound wave scattering and attenuation caused by the leakage channels (the absorption of sound waves by water causes abrupt changes in reflected energy). In contrast, the abnormal signal waveforms in non-leaking areas contain only stable background noise and no abnormal fluctuations. Therefore, chaotic spikes or abrupt changes in amplitude in the abnormal signal waveforms directly indicate the presence of leakage defects and are the core characteristics for determining leakage.

[0066] The process involves acquiring the peaks in the abnormal signal waveform at the test point. In this embodiment, the peaks can be acquired by: obtaining the average value of the ultrasonic amplitude of each maximum value in the abnormal signal waveform at the test point, which is used as the reference ultrasonic amplitude. A threshold is set, which is greater than the reference ultrasonic amplitude, for example, the threshold is 1.2 times the reference ultrasonic amplitude. The maximum values ​​in the abnormal signal waveform at the test point are compared with the threshold, and the maximum values ​​that are greater than or equal to the threshold are acquired and used as the peaks in the abnormal signal waveform at the test point. Furthermore, this embodiment acquires the maximum value in the abnormal signal waveform at the test point, i.e., the maximum ultrasonic amplitude. The ultrasonic amplitude at each moment in the abnormal signal waveform at the test point is divided by the maximum ultrasonic amplitude to obtain the normalized ultrasonic amplitude at each moment in the abnormal signal waveform at the test point. The ultrasonic amplitude mentioned below refers to the normalized ultrasonic amplitude. It should be understood that in extreme cases, if the maximum ultrasonic amplitude is 0, the abnormal signal waveform is a straight line with no fluctuations and zero values, directly indicating that there is no leakage in the underground structure exterior wall at the test point.

[0067] The amplitude difference between any two adjacent peaks in the abnormal signal waveform of the test point is obtained, where the amplitude difference is the absolute value of the difference in ultrasonic amplitude. The amplitude differences between all adjacent peaks in the abnormal signal waveform of the test point are sequentially arranged to form a peak amplitude difference sequence for the test point. The degree of amplitude difference fluctuation in the peak amplitude difference sequence of the test point is determined. In an exemplary embodiment, the standard deviation is used to characterize the degree of fluctuation; that is, the standard deviation of the amplitude differences in the peak amplitude difference sequence of the test point is calculated as the degree of amplitude difference fluctuation.

[0068] The initial probability of leakage in the underground structural exterior wall at the test point is obtained based on the degree of amplitude difference fluctuation at the test point. In an exemplary embodiment, since the values ​​of each element in the peak amplitude difference sequence are all in the range of 0-1 after normalization, the maximum value range of the standard deviation of the peak amplitude difference sequence is 0-0.5. Therefore, this embodiment obtains the initial probability of leakage in the underground structural exterior wall at the test point based on the degree of amplitude difference fluctuation through a preset nonlinear mapping function. The greater the degree of amplitude difference fluctuation, the more chaotic the abnormal signal, and the higher the initial probability of leakage. Leakage detection is performed on the underground structural exterior wall at the test point based on the initial probability of leakage, for example, by comparing it with a first preset leakage threshold. If the initial probability of leakage in the underground structural exterior wall at the test point is greater than or equal to the first preset leakage threshold, it is determined that there is leakage in the underground structural exterior wall at the test point. The value range of the first preset leakage threshold is 0-1, and as an example, it is set to 0.4.

[0069] One example of a mapping function is as follows: ;k represents an adjustable gain coefficient, for example, a value of 5, used to adjust the steepness of the curve, mapping any non-negative fluctuation value to Within the probability range.

[0070] Since leakage defects (such as cracks and seepage channels) are physically existing continuous structural anomalies, the resulting sound wave scattering and reflection disturbances will affect adjacent detection points along the direction of defect extension. Therefore, as a better implementation method, after obtaining the initial probability of leakage in the underground structure's exterior wall at the detection point, the underground structure exterior wall leakage detection method provided in this embodiment also performs the following subsequent processes: Obtain the neighboring detection points of the detection point to be tested. For example, the detection points adjacent to the top, bottom, left, and right sides of the detection point to be tested can be used as the neighboring detection points of the detection point to be tested. These detection points can be the detection points determined by the coarse scan.

[0071] If a leak exists at the test point, it will typically affect neighboring test points, causing both the test point and neighboring test points to exhibit chaotic spikes or abrupt amplitude changes in their abnormal signal waveforms, with consistent location and trend of the abnormal features. Random interference (such as coupling agent bubbles, wall protrusions, and equipment electrical noise) only affects a single test point, and neighboring test points will not exhibit similar anomalies synchronously. Therefore, comparing multiple test points can effectively eliminate such accidental errors and avoid misjudgment of a single test point. Thus, the similarity between the abnormal signal waveform of the test point and the abnormal signal waveforms of its neighboring test points is obtained. In an exemplary embodiment, for any neighboring test point, the Pearson correlation coefficient between the abnormal signal waveform of the test point and the abnormal signal waveform of that neighboring test point is obtained, and the Pearson correlation coefficient is normalized. The result is the similarity between the abnormal signal waveform of the test point and the abnormal signal waveform of that neighboring test point. The normalization method for the Pearson correlation coefficient can be: (Pearson correlation coefficient + 1) / 2. Then, the average similarity between the abnormal signal waveform of the test point and the abnormal signal waveforms of its neighboring test points is calculated as the similarity between the test point and its neighboring test points. The higher the similarity between the abnormal signal waveforms of the test point and its neighboring test points, the higher the probability of leakage in the underground structure's external wall at the test point; the two are positively correlated.

[0072] The higher the initial probability of leakage in the underground structure's exterior wall at the test point, the higher the final probability of leakage in the underground structure's exterior wall at the test point; the two are positively correlated. In an exemplary embodiment, the product of the initial probability of leakage in the underground structure's exterior wall at the test point and the similarity of the abnormal signal waveform between the test point and its neighboring test points is calculated, and the result is taken as the final probability of leakage in the underground structure's exterior wall at the test point.

[0073] The leakage detection of the underground structural exterior wall at the test point is performed based on the ultimate probability of leakage at that point. For example, the probability is compared with a second preset leakage threshold. If the ultimate probability of leakage at the test point is greater than or equal to the second preset leakage threshold, then leakage is determined to exist in the underground structural exterior wall at the test point. The value range of the second preset leakage threshold is 0-1; as an example, a value of 0.3 is used.

[0074] In addition, this embodiment can also analyze the final probability of leakage of the underground structure exterior wall at multiple detection points. If the final probability of leakage of the underground structure exterior wall at multiple adjacent detection points is greater than or equal to the second preset leakage threshold, it is determined that these detection points correspond to the extension area of ​​the same leakage channel. Such continuous signals often reflect that the leakage channel is linear or strip-shaped. The strongest signal is usually the source of leakage or the core section of the channel, and it is marked.

[0075] In one exemplary embodiment, this embodiment also provides an underground structure exterior wall leakage detection system, including: a memory and a processor; the memory is connected to the processor, and the memory is used to store program instructions; the processor is used to implement the steps in the above-described underground structure exterior wall leakage detection method embodiment when the program instructions are executed.

[0076] In one exemplary embodiment, this embodiment also provides an underground structure exterior wall leakage detection device, comprising: a computer-readable storage medium storing a computer program, which, when executed by a processor, implements the steps in the above-described underground structure exterior wall leakage detection method embodiment.

[0077] It should be noted that the order of the above embodiments of the present invention is merely for descriptive purposes and does not represent the superiority or inferiority of the embodiments. The processes depicted in the accompanying drawings do not necessarily require a specific or sequential order to achieve the desired result. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0078] The various embodiments in this specification are described in a progressive manner. The same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on describing the differences from other embodiments.

Claims

1. A method for detecting leakage in the exterior walls of underground structures, characterized in that, include: By analyzing the chaotic ultrasonic waveforms at the detection points of the underground structure's exterior wall, the probability of the steel reinforcement area at the detection points can be obtained. Based on the symmetry of the possible transverse and longitudinal reinforcement areas within the local area of ​​the detection point, the reference value of the detection point for participating in the acquisition of the standard waveform of the reinforcement is determined. The target detection points are selected based on the reference value of each detection point; The standard amplitude of the standard waveform of the steel reinforcement at each moment is obtained from the probability of the steel reinforcement area at each detection point within the target range of the target detection point and the ultrasonic amplitude at each detection point at each moment. The standard waveform of the steel bar is removed from the ultrasonic waveform to obtain the abnormal signal waveform; Based on the abnormal signal waveform, leakage detection is performed on the exterior walls of the underground structure.

2. The method for detecting leakage in the exterior walls of underground structures as described in claim 1, characterized in that, The process of obtaining the probability of the rebar area includes: Select several peaks from the maxima in the ultrasonic waveform; The peak intensity is obtained from the average amplitude of the peak. The degree of fluctuation in the peak time interval is obtained from the time interval between adjacent peaks; The probability of the rebar region is obtained from the peak intensity, the fluctuation degree of the peak time interval, and the number of peaks; the probability of the rebar region is positively correlated with the peak intensity and the number of peaks, and negatively correlated with the fluctuation degree of the peak time interval.

3. The method for detecting leakage in the exterior walls of underground structures as described in claim 1, characterized in that, The reference acquisition process includes: The probability difference of the rebar region for each pair of symmetrical points in the horizontal direction with the detection point as the center is obtained to obtain the horizontal symmetry feature; the pair of symmetrical points includes two other detection points that have a positional symmetry relationship with the detection point as the center; the horizontal symmetry feature is inversely correlated with the probability difference of the rebar region for each pair of symmetrical points in the horizontal direction. The longitudinal symmetry feature is obtained by acquiring the probability difference of the rebar region for each pair of symmetrical points in the longitudinal direction centered on the detection point; the longitudinal symmetry feature is inversely correlated with the probability difference of the rebar region for each pair of symmetrical points in the longitudinal direction. The reference is obtained by integrating the horizontal symmetry features and the vertical symmetry features.

4. The method for detecting leakage in the exterior walls of underground structures as described in claim 1, characterized in that, The selection of target detection points based on the reference value of each detection point includes: The reference value of each detection point is determined and the value of the preset reference value threshold is determined. If there is a detection point with a reference value greater than the preset reference value threshold, the detection point with the highest reference value is selected as the target detection point.

5. The method for detecting leakage in the exterior walls of underground structures as described in claim 1, characterized in that, The process of obtaining the standard amplitude includes: The influence weight of each detection point is obtained from the probability of the rebar area at each detection point within the target range of the target detection point; the influence weight is positively correlated with the probability of the rebar area. Based on the influence weight of each detection point, the ultrasonic amplitude of each detection point at any time is weighted and summed to obtain the standard amplitude of the steel reinforcement standard waveform at any time. Accordingly, the standard waveform of the reinforcing bar is composed of the standard amplitude at each moment.

6. The method for detecting leakage in the exterior walls of underground structures as described in claim 1, characterized in that, The process of acquiring the abnormal signal waveform includes: Time alignment is performed between the ultrasonic waveform and the standard waveform of the reinforcing bar. The abnormal signal waveform is obtained by subtracting the standard waveform of the steel bar from the time-aligned ultrasonic waveform.

7. The method for detecting leakage in the exterior walls of underground structures as described in claim 1, characterized in that, The method of detecting leakage in the exterior walls of underground structures based on abnormal signal waveforms includes: Obtain the peak amplitude difference sequence of the abnormal signal waveform at the test point, wherein the peak amplitude difference sequence is composed of the amplitude difference between two adjacent peaks in the abnormal signal waveform; The amplitude difference fluctuation degree of the peak amplitude difference sequence is determined to obtain the initial probability of leakage of the underground structure exterior wall at the test point.

8. The method for detecting leakage in the exterior walls of underground structures as described in claim 7, characterized in that, After obtaining the initial probability of leakage in the underground structure's exterior wall at the test point, the method for detecting leakage in the underground structure's exterior wall further includes: Obtain the similarity of the abnormal signal waveforms between the detection point to be tested and its neighboring detection points; Based on the similarity of the abnormal signal waveform and the initial probability of leakage in the underground structure's exterior wall, the final probability of leakage in the underground structure's exterior wall at the test point is obtained; the final probability of leakage in the underground structure's exterior wall is positively correlated with both the similarity of the abnormal signal waveform and the initial probability of leakage in the underground structure's exterior wall.

9. A system for detecting leakage in the exterior walls of underground structures, characterized in that, include: Memory and processor; The memory is connected to the processor; The memory is used to store program instructions; The processor is configured to implement the method for detecting leakage in the exterior walls of underground structures as described in any one of claims 1-8 when program instructions are executed.

10. A device for detecting leakage in the exterior walls of underground structures, characterized in that, The invention includes a computer-readable storage medium storing a computer program that, when executed by a processor, implements the steps of the method for detecting leakage in the exterior walls of underground structures according to any one of claims 1-8.

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