Pipe gallery joint rubber laminated piezoelectric leakage monitoring device and method

Abstract

The application discloses a kind of pipe gallery joint rubber laminated piezoelectric leakage monitoring device and method, it is related to pipe gallery leakage monitoring technical field, to solve the problem of existing pipe gallery joint leakage monitoring, waterproof adhesive strip cannot be positioned leakage point, and traditional sensor is difficult to dynamically monitor pressure signal in complex environment, there is slow response, difficult to locate, susceptible to interference problem.The device of the present application comprises pipe gallery body and laminated adhesive strip.Laminated adhesive strip is alternately laminated by at least one piezoelectric ceramic layer and at least two rubber layers, and is combined by vulcanization, is embedded in the end joint of pipe gallery body and is in compression state.Piezoelectric ceramic layer includes excitation piezoelectric ceramic layer and receiving piezoelectric ceramic layer, and multiple piezoelectric ceramic segments are arranged in the length direction of laminated adhesive strip.The precise positioning of leakage point along the way is realized, the common mode interference of environment is eliminated, the response speed reaches millisecond level alarm, and the adhesive strip has high flexibility and durability, and adapts to uneven settlement of pipe gallery.

Description

Technical Field

[0001] This invention belongs to the field of pipe gallery leakage monitoring technology, specifically, it relates to a pipe gallery joint rubber laminate piezoelectric leakage monitoring device and method. Background Technology

[0002] Integrated utility tunnels are a crucial component of urban underground infrastructure. Their joints are prone to leakage due to uneven settlement and temperature variations. Currently, waterproof sealing strips are commonly used to seal these joints. However, traditional waterproof strips only block water flow and cannot monitor leakage in real time, let alone pinpoint the exact location of the leak. Existing technologies attempt to use pressure sensors or water immersion sensors placed near the joints, but due to the humid environment, vibration, and electromagnetic interference in the tunnels, the sensor signals suffer from poor stability and long response times (typically on the order of minutes), making it difficult to achieve water permeation alarms at the second or millisecond level. Furthermore, a single sensor cannot distinguish between normal pressure fluctuations and pressure changes caused by leakage, easily leading to false alarms. Therefore, there is an urgent need for a device and method that can ensure the waterproof flexibility of the joints while achieving highly sensitive leakage monitoring and location of leak points. Summary of the Invention

[0003] In order to overcome the above-mentioned technical problems, the purpose of this invention is to provide a device and method for monitoring piezoelectric leakage of rubber laminates in pipe gallery joints.

[0004] The objective of this invention can be achieved through the following technical solutions: A pipe gallery joint rubber laminated piezoelectric leakage monitoring device includes a pipe gallery body and a laminated rubber strip, wherein the laminated rubber strip is an integral rubber strip formed by alternating layers of at least one piezoelectric ceramic layer and at least two rubber layers and vulcanization bonding. The laminated rubber strip is embedded in the joint at the end of the pipe gallery body, and the laminated rubber strip is in a compressed state within the joint. The piezoelectric ceramic layer includes at least one excitation piezoelectric ceramic layer and at least one receiving piezoelectric ceramic layer. The excitation piezoelectric ceramic layer is used to generate mechanical vibration in response to an externally applied excitation electrical signal, and the receiving piezoelectric ceramic layer is used to sense the mechanical vibration and output a response electrical signal. The laminated adhesive strip is divided into multiple piezoelectric ceramic segments along its length. Each piezoelectric ceramic segment contains at least one piezoelectric ceramic layer, and each piezoelectric ceramic segment is connected to an independent signal lead-out line for realizing the location of leakage along the line. The signal lead has a stress relief structure at one end near the laminated adhesive strip. The stress relief structure includes a flexible sheath, spring tube, or corrugated tube extending from the end of the laminated adhesive strip.

[0005] As a preferred embodiment of the present invention, the piezoelectric ceramic layer is disposed between two adjacent rubber layers.

[0006] As a preferred embodiment of the present invention, the rubber layer is made of nitrile rubber or EPDM rubber, and the piezoelectric ceramic layer is made of lead zirconate titanate piezoelectric ceramic.

[0007] In a preferred embodiment of the present invention, the rubber layer comprises, by weight, 100 parts of a rubber matrix, 20-80 parts of a non-conductive reinforcing filler, and 1-3 parts of a vulcanizing agent; the rubber matrix is ​​nitrile rubber or ethylene propylene diene monomer (EPDM) rubber, the non-conductive reinforcing filler is at least one of silica, carbon black, calcium carbonate, or silicate, and the volume resistivity of the rubber layer is greater than 10 Ω·cm. 12 Ω·cm.

[0008] As a preferred embodiment of the present invention, the thickness of each rubber layer is gradient-distributed in the stack thickness direction, with the thickness of the rubber layer near the outer side being greater than that of the rubber layer near the inner side; the thickness of the piezoelectric ceramic layer is 0.1mm to 1.0mm, the thickness of the rubber layer is 0.5mm to 2.0mm, and the thickness of the rubber layer is greater than that of the piezoelectric ceramic layer.

[0009] As a preferred embodiment of the present invention, the laminated adhesive strip further includes at least one layer of reference piezoelectric ceramic element, which is isolated from the joint pressure and is used to collect environmental common-mode signals; The device also includes a differential signal processing module for differentially processing the output signal of the piezoelectric ceramic layer and the output signal of the reference piezoelectric ceramic element to eliminate common-mode interference.

[0010] A method for monitoring piezoelectric leakage of rubber laminates in pipe gallery joints based on the above-mentioned device includes the following steps: S1. The laminated adhesive strip is embedded in the joint; S2. Continuously acquire and receive the response electrical signal output by the piezoelectric ceramic layer through the signal lead-out line; S3. Analyze the response electrical signal. When it is determined that the amplitude attenuation, phase shift, or frequency response change of the response electrical signal relative to the excitation electrical signal exceeds a preset threshold, output a leakage alarm signal.

[0011] As a preferred technical solution of the present invention, in step S3, the response electrical signal is first subjected to frequency domain analysis to extract characteristic frequency components related to leakage. When the amplitude of the characteristic frequency components exceeds a preset amplitude threshold and the duration exceeds a preset time threshold, a leakage alarm signal is output. The duration threshold is 1 to 50 milliseconds.

[0012] As a preferred embodiment of the present invention, it further includes a phased warning step: when the instantaneous amplitude of the response electrical signal exceeds a first threshold, a first-level warning signal is output; when more than a predetermined number of threshold-exceeding events are detected within a preset time window, a second-level warning signal is output.

[0013] Compared with the prior art, the present invention has the following beneficial effects: 1. Precise Leakage Location: By dividing the laminated adhesive strip into multiple independent piezoelectric ceramic segments along its length, with each segment connected to an independent signal lead, when leakage occurs at the location of a segment, the response electrical signal output by that segment changes significantly, thereby enabling the location of the leakage along the entire length of the strip and solving the problem that traditional methods cannot determine the specific leakage point.

[0014] 2. Fast response speed: By adopting the mechanical vibration and electrical signal conversion mechanism of the piezoelectric ceramic layer, pressure changes caused by leakage can be detected within milliseconds. Combined with the duration threshold setting of 1 to 50 milliseconds, rapid alarm can be achieved.

[0015] 3. Strong anti-interference capability: At least one layer of reference piezoelectric ceramic element is set to isolate it from the joint pressure, and the environmental common-mode interference (such as temperature drift and vibration noise) is eliminated through differential signal processing module, which improves the reliability and accuracy of monitoring.

[0016] 4. Good flexibility and durability: The rubber layer and the piezoelectric ceramic layer are alternately laminated and vulcanized together. The thickness of the rubber layer is greater than that of the piezoelectric ceramic layer, and the outer rubber layer is even thicker. This ensures the flexibility of the rubber strip and prevents it from being damaged when the pipe gallery settles unevenly or the joints are misaligned. It also maintains its waterproof and monitoring functions for a long time.

[0017] 5. Phased early warning: By setting different thresholds and cumulative event counts, a tiered response from early warning to alarm can be achieved, avoiding false alarms or missed alarms caused by a single threshold. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the overall structure of the present invention; Figure 2 This is a cross-sectional view of the laminated adhesive strip of the present invention; Figure 3 This is an enlarged view of point A in the present invention; Figure 4This is the overall flowchart of the present invention.

[0020] Figure label: 1. Pipe gallery body; 2. Joint; 3. Laminated rubber strip; 31. Piezoelectric ceramic layer; 32. Rubber layer; 4. Signal lead-out line; 5. Stress relief structure. Detailed Implementation

[0021] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby providing a clearer and more explicit definition of the scope of protection of the present invention: Example 1

[0022] I. Device Structure A pipe gallery joint rubber laminate piezoelectric leakage monitoring device includes a pipe gallery body 1 and laminate rubber strips 3.

[0023] Specifically, the laminated rubber strip 3 is an integral strip formed by alternating layers of two rubber layers 31 and one piezoelectric ceramic layer 32, bonded together by high-temperature vulcanization. The specific lamination sequence is: first rubber layer 31, piezoelectric ceramic layer 32, second rubber layer 31. The piezoelectric ceramic layer 32 is completely enclosed by the rubber layers 31, that is, the piezoelectric ceramic layer 32 is disposed between the first rubber layer 31 and the second rubber layer 31.

[0024] Specifically, the rubber layer 31 is made of nitrile rubber (NBR). The piezoelectric ceramic layer 32 is made of lead zirconate titanate piezoelectric ceramic (PZT-5A type). After the laminated rubber strip 3 is vulcanized, the piezoelectric ceramic layer 32 is polarized with a polarization voltage of 2kV / mm, a polarization temperature of 120℃, and a polarization time of 30 minutes.

[0025] Specifically, the cross-section of the laminated rubber strip 3 is rectangular, with a length of 6 mm, a width of 35 mm, and a thickness of 6 mm. Among them, the thickness of the piezoelectric ceramic layer 32 is 0.5 mm, and the thickness of the upper and lower rubber layers 31 is 2.75 mm each.

[0026] Specifically, the piezoelectric ceramic layer 32 includes an excitation piezoelectric ceramic layer and a receiving piezoelectric ceramic layer, which are arranged side by side in the same horizontal plane with a horizontal distance of 5 mm between them. The upper and lower surfaces of the excitation piezoelectric ceramic layer are connected to the first excitation wire and the second excitation wire respectively through conductive silver paste, and the upper and lower surfaces of the receiving piezoelectric ceramic layer are connected to the first receiving wire and the second receiving wire respectively through conductive silver paste. The excitation wire and the receiving wire together constitute the signal lead-out line 4.

[0027] Specifically, the laminated adhesive strip 3 is segmented along its length into multiple piezoelectric ceramic segments. The segmentation method is as follows: the length of the laminated adhesive strip 3 is divided into segments every 250mm, and each segment contains a set of excitation piezoelectric ceramic layers and a set of receiving piezoelectric ceramic layers. The piezoelectric ceramic layers 32 between adjacent segments are physically completely disconnected, with a gap of 15mm, and this gap area is filled only by the rubber layer 31. The excitation and receiving wires for each segment are independently led out, meaning each segment has four wires (two excitation and two receiving). The signal lead-out lines 4 of all segments extend from the same end of the laminated adhesive strip 3.

[0028] Specifically, a stress relief structure 5 is provided on each signal lead 4 near the end of the laminated rubber strip 3. In this embodiment, the stress relief structure 5 is a corrugated tube with a length of 40 mm. The corrugated tube is sleeved on the outside of the signal lead 4. One end of the corrugated tube is fixed to the end face of the laminated rubber strip 3 by vulcanization, and the other end of the corrugated tube is a free end. The signal lead 4 passes through the free end and connects to an external data acquisition device. The corrugated tube is made of polytetrafluoroethylene, with a wall thickness of 0.3 mm and a corrugation spacing of 2 mm.

[0029] II. Installation Method The aforementioned laminated adhesive strip 3 is embedded in the joint 2 between the ends of the two sections of the pipe gallery body 1. During installation, ensure that the upper surface of the laminated adhesive strip 3 is tightly fitted with the mating surface of the first section of the pipe gallery body 1, and the lower surface of the laminated adhesive strip 3 is tightly fitted with the mating surface of the second section of the pipe gallery body 1. The length direction of the laminated adhesive strip 3 is consistent with the extension direction of the joint 2.

[0030] The laminated rubber strip 3 is in a compressed state within the joint 2, with a compression amount of 12% of the original thickness of the laminated rubber strip 3. This compression is achieved as follows: when the two sections of the pipe gallery body 1 are joined together, the designed width of the joint 2 is 5mm, while the original thickness of the laminated rubber strip 3 is 6mm. After installation, the rubber strip is compressed by 1mm, achieving a compression rate of 12%.

[0031] III. Monitoring Methods Leakage monitoring using the above-mentioned device includes the following steps: S1. The laminated adhesive strip 3 is embedded in the joint 2 so that the two surfaces of the laminated adhesive strip 3 are tightly fitted to the mating surfaces of the two sections of the pipe gallery body 1.

[0032] S2. Continuously acquire the response electrical signal output by the piezoelectric ceramic layer through signal lead-out line 4. The specific acquisition method is as follows: an external signal generator applies a continuous sinusoidal excitation signal with a frequency of 80kHz and a peak-to-peak voltage of 10V to the piezoelectric ceramic layer through an excitation wire; the response electrical signal output by the piezoelectric ceramic layer is received and transmitted to an oscilloscope or data acquisition card through a receiving wire, with a sampling frequency of 1MHz.

[0033] S3. Analyze the response electrical signal: First, perform a Fast Fourier Transform on the response electrical signal to obtain the amplitude at the 80kHz frequency component. Compare this amplitude with the initial calibration value (the 80kHz amplitude measured under dry, leak-free conditions) and calculate the amplitude attenuation rate. When the amplitude attenuation rate exceeds 25% and the duration exceeds 5 milliseconds, a leakage alarm signal is output.

[0034] The initial calibration value is measured within 24 hours after the installation of the laminated adhesive strip 3. During the measurement, ensure that the joint 2 is dry, leak-free, and the ambient temperature is within the range of 15℃ to 25℃. Example 2

[0035] The differences between this embodiment and Embodiment 1 are as follows: I. Differences in Device Structure 1. The laminated rubber strip 3 is formed by alternating layers of three rubber layers 31 and two piezoelectric ceramic layers 32, with the specific lamination sequence being: first rubber layer 31, first piezoelectric ceramic layer 32, second rubber layer 31, second piezoelectric ceramic layer 32, and third rubber layer 31.

[0036] In this design, the first piezoelectric ceramic layer 32 serves as the excitation piezoelectric ceramic layer, and the second piezoelectric ceramic layer 32 serves as the receiving piezoelectric ceramic layer. That is, the excitation layer and the receiving layer are arranged vertically along the stack thickness direction, rather than horizontally side by side.

[0037] 2. The laminated adhesive strip 3 also includes a reference piezoelectric ceramic element. This reference piezoelectric ceramic element is made of the same material as the receiving piezoelectric ceramic layer (both are PZT-5A type) and has the same dimensions. This reference piezoelectric ceramic element is encapsulated within an independent, sealed chamber inside the laminated adhesive strip 3. This sealed chamber is formed by an additional rubber layer 31, is filled with air, and is connected to the external atmosphere via a capillary tube, thus ensuring that the pressure inside the chamber is always equal to atmospheric pressure. However, the upper and lower surfaces of this reference piezoelectric ceramic element do not come into contact with any pressure within the joint 2; that is, water pressure or pressure changes within the joint 2 do not directly affect the reference piezoelectric ceramic element. Nevertheless, this reference piezoelectric ceramic element can still sense changes in ambient temperature and overall mechanical vibration.

[0038] 3. The device also includes a differential signal processing module. This module uses an AD620 instrumentation amplifier chip and its surrounding resistors and capacitors. The output signal from the receiving piezoelectric ceramic layer is connected to the non-inverting input of the AD620, the output signal from the reference piezoelectric ceramic element is connected to the inverting input of the AD620, the reference terminal of the AD620 is grounded, and the output is the differential signal. The differential gain is set to 10.

[0039] II. Differences in Installation Methods The independent sealed chamber of the reference piezoelectric ceramic element is integrally formed during the vulcanization molding of the laminated adhesive strip 3, requiring no additional on-site operations. The remaining installation methods are the same as in Example 1.

[0040] III. Differences in Monitoring Methods In step S2, the acquired signals include: the raw signal output from the received piezoelectric ceramic layer, the common-mode signal output from the reference piezoelectric ceramic element, and the differential signal output from the differential signal processing module. This method uses differential signals for analysis.

[0041] In step S3, frequency domain analysis is performed on the differential signal to extract the 80kHz characteristic frequency component. When the amplitude of this characteristic frequency component decays by more than 20% relative to the initial calibration value and the duration exceeds 10 milliseconds, a leakage alarm signal is output.

[0042] In addition, this embodiment also includes a phased warning step: when the amplitude attenuation rate of the differential signal at 80kHz is between 10% and 20% and the duration exceeds 5 milliseconds, a first-level warning signal (yellow alarm light flashes) is output; when 3 or more over-threshold events (attenuation rate ≥ 20% and duration ≥ 10 milliseconds) are detected within a 10-second time window, a second-level warning signal (buzzer sounds intermittently) is output regardless of whether a single event has triggered an alarm. Example 3

[0043] The differences between this embodiment and Embodiment 1 are as follows: I. Differences in Rubber Layer Material Formulation The rubber layer 31 comprises, by weight, 100 parts of nitrile rubber (NBR), 40 parts of silica, 3 parts of carbon black, 1.5 parts of sulfur, 5 parts of zinc oxide, 1 part of stearic acid, 1.2 parts of accelerator DM, and 1 part of antioxidant RD.

[0044] The above components were mixed evenly on a two-roll mill at a mixing temperature of 50°C for 15 minutes to obtain a compound. Then, it was stacked with the polarized piezoelectric ceramic layer 32 in a mold and vulcanized at 160°C and 10MPa pressure for 30 minutes to obtain a laminated rubber strip 3 with an integral structure.

[0045] Tests showed that the volume resistivity of the rubber layer 31 in this embodiment is 8 × 10⁻⁶. 12 The resistance (Ω·cm) measured using a high-resistance meter at 500V DC voltage meets the insulation requirements, thus avoiding electrical short circuits between the piezoelectric ceramic layers 32.

[0046] II. Differences between piezoelectric ceramic materials The piezoelectric ceramic layer 32 is made of PZT-5H type piezoelectric ceramic, with a piezoelectric constant d33 of 650pC / N and a relative permittivity of 3800.

[0047] III. Differences in Stress-Relief Structures In this embodiment, the stress relief structure 5 adopts a spring tube structure. Specifically, a flexible sheath with a length of 30mm extends from the end of the laminated rubber strip 3. This flexible sheath is made of the same material as the rubber layer 31 of the laminated rubber strip 3 and is integrally formed. The inner diameter of the flexible sheath is slightly larger than the outer diameter of the signal lead 4. A helical spring is installed in the annular gap between the flexible sheath and the signal lead 4. The helical spring has a length of 25mm, a wire diameter of 0.3mm, and an outer diameter of 3mm. One end of the helical spring is fixed to the end face of the laminated rubber strip 3 with adhesive, and the other end of the helical spring freely rests against the outer surface of the insulation layer of the signal lead 4. When the signal lead 4 is stretched or bent, the helical spring undergoes elastic deformation to absorb stress and prevent the root of the signal lead 4 (i.e., the connection point with the piezoelectric ceramic layer 32) from bearing excessive stress.

[0048] IV. Differences in Monitoring Methods In step S3, frequency domain analysis is not performed; instead, the instantaneous amplitude of the response electrical signal output by the piezoelectric ceramic layer is directly monitored. Specifically, the response electrical signal is converted into a voltage signal by a charge amplifier and then sent to a comparator circuit. When the instantaneous voltage value exceeds 2.5 times the normal baseline value (the average amplitude when there is no leakage) and the duration exceeds 1 millisecond, the comparator outputs a high level, triggering a leakage alarm signal.

[0049] Working principle: The laminated rubber strip 3 is embedded in the joint 2 at the end of the pipe gallery body 1 and kept in a compressed state, so that the two surfaces of the laminated rubber strip 3 are tightly attached to the mating surfaces of the two sections of the pipe gallery body 1. An external excitation electrical signal is applied to the excitation piezoelectric ceramic layer through the signal lead 4, and the excitation piezoelectric ceramic layer generates mechanical vibration under the inverse piezoelectric effect; this vibration is transmitted to the receiving piezoelectric ceramic layer through the rubber layer 31, and the receiving piezoelectric ceramic layer converts the induced vibration into a response electrical signal under the direct piezoelectric effect, and outputs it through the signal lead 4.

[0050] When no leakage occurs at the pipe gallery joint, the acoustic boundary conditions inside the laminated rubber strip 3 and at the contact interface are stable, and the response electrical signal remains within a certain range. When leakage occurs, leaking water or water pressure intrudes into the joint 2, changing the stress distribution and interface contact state of the laminated rubber strip 3, leading to changes in the propagation characteristics of mechanical vibration, thereby causing amplitude attenuation, phase shift, or frequency response changes in the response electrical signal. By continuously monitoring the change in the response electrical signal relative to the excitation electrical signal and comparing it with a preset threshold, it is possible to determine whether leakage has occurred.

[0051] To pinpoint the location of leaks, the laminated adhesive strip 3 is divided into multiple independent piezoelectric ceramic segments along its length, each segment connected to an independent signal lead 4. When a leak occurs at the location of a particular segment, only the response electrical signal of that segment changes significantly, thus determining the location of the leak.

[0052] The stress-relieving structure 5 installed near the end of the signal lead 4, close to the laminated rubber strip 3, can absorb displacement differences when uneven settlement or changes in joint width occur in the pipe gallery, preventing breakage at the root of the signal lead 4. The installation of a reference piezoelectric ceramic element and differential processing of its output signal with the receiving piezoelectric ceramic layer can eliminate common-mode interference from ambient temperature, overall vibration, etc., improving monitoring accuracy. The phased early warning mechanism achieves a graded response from early warning to alarm by setting different thresholds and cumulative event counts.

[0053] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0054] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A piezoelectric leakage monitoring device for rubber laminates at pipe gallery joints, characterized in that, It includes the pipe gallery body (1) and the laminated rubber strip (3), wherein the laminated rubber strip (3) is an integral rubber strip formed by alternating layers of at least one piezoelectric ceramic layer (32) and at least two rubber layers (31) and vulcanization. The laminated rubber strip (3) is embedded in the joint (2) at the end of the pipe gallery body (1), and the laminated rubber strip (3) is in a compressed state in the joint (2); The piezoelectric ceramic layer (32) includes at least one excitation piezoelectric ceramic layer and at least one receiving piezoelectric ceramic layer. The excitation piezoelectric ceramic layer is used to generate mechanical vibration in response to an externally applied excitation electrical signal, and the receiving piezoelectric ceramic layer is used to sense the mechanical vibration and output a response electrical signal. The laminated adhesive strip (3) is divided into multiple piezoelectric ceramic segments along its length. Each piezoelectric ceramic segment contains at least one piezoelectric ceramic layer (32), and each piezoelectric ceramic segment is connected to an independent signal lead (4) for realizing the location of leakage along the path. The signal lead (4) has a stress relief structure (5) at one end near the laminated adhesive strip (3). The stress relief structure (5) includes a flexible sheath, spring tube or corrugated tube extending from the end of the laminated adhesive strip (3).

2. The piezoelectric leakage monitoring device for rubber laminated pipe gallery joints according to claim 1, characterized in that, The piezoelectric ceramic layer (32) is disposed between two adjacent rubber layers (31).

3. The pipe gallery joint rubber laminate piezoelectric leakage monitoring device according to claim 1, characterized in that, The rubber layer (31) is made of nitrile rubber or EPDM rubber, and the piezoelectric ceramic layer (32) is made of lead zirconate titanate piezoelectric ceramic.

4. The pipe gallery joint rubber laminate piezoelectric leakage monitoring device according to claim 3, characterized in that, The rubber layer (31) comprises, by weight, 100 parts of rubber matrix, 20-80 parts of non-conductive reinforcing filler, and 1-3 parts of vulcanizing agent; the rubber matrix is ​​nitrile rubber or ethylene propylene diene monomer (EPDM) rubber, the non-conductive reinforcing filler is at least one of silica, carbon black, calcium carbonate, or silicate, and the volume resistivity of the rubber layer (31) is greater than 10 Ω·cm. 12 Ω·cm.

5. The piezoelectric leakage monitoring device for rubber laminated pipe gallery joints according to claim 1, characterized in that, The thickness of each rubber layer (31) is gradient-distributed in the stack thickness direction, with the thickness of the rubber layer near the outer side being greater than that of the rubber layer near the inner side; the thickness of the piezoelectric ceramic layer (32) is 0.1 mm to 1.0 mm, the thickness of the rubber layer (31) is 0.5 mm to 2.0 mm, and the thickness of the rubber layer (31) is greater than that of the piezoelectric ceramic layer (32).

6. The piezoelectric leakage monitoring device for rubber laminated pipe gallery joints according to claim 1, characterized in that, The laminated adhesive strip (3) also includes at least one layer of reference piezoelectric ceramic element, which is isolated from the joint pressure and is used to collect environmental common mode signals; The device also includes a differential signal processing module for differentially processing the output signal of the piezoelectric ceramic layer (32) and the output signal of the reference piezoelectric ceramic element to eliminate common-mode interference.

7. A method for monitoring piezoelectric leakage of rubber laminated pipe gallery joints based on the device described in any one of claims 1-6, characterized in that, Includes the following steps: S1. The laminated adhesive strip (3) is embedded in the joint (2); S2. The response electrical signal output by the piezoelectric ceramic layer is continuously acquired and received through the signal lead-out line (4); S3. Analyze the response electrical signal. When it is determined that the amplitude attenuation, phase shift, or frequency response change of the response electrical signal relative to the excitation electrical signal exceeds a preset threshold, output a leakage alarm signal.

8. The method for monitoring piezoelectric leakage of rubber laminates in pipe gallery joints according to claim 7, characterized in that, In step S3, the response electrical signal is first subjected to frequency domain analysis to extract characteristic frequency components related to leakage. When the amplitude of the characteristic frequency component exceeds a preset amplitude threshold and the duration exceeds a preset time threshold, a leakage alarm signal is output. The duration threshold is 1 to 50 milliseconds.

9. The method for monitoring piezoelectric leakage of rubber laminates in pipe gallery joints according to claim 7, characterized in that, It also includes a phased warning process: when the instantaneous amplitude of the response electrical signal exceeds the first threshold, a first-level warning signal is output; when more than a predetermined number of threshold-exceeding events are detected within a preset time window, a second-level warning signal is output.

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