Geomembrane deformation leakage detection system based on built-in piezoelectric film and construction method

Abstract

The invention discloses a piezoelectric film built-in geomembrane deformation leakage detection system and a construction method, and relates to the field of piezoelectric sensing technology and anti-seepage technology, the detection system comprises a distributed piezoelectric film, a multi-channel impedance acquisition instrument and a multi-channel voltage acquisition instrument, the distributed piezoelectric films are laminated between the lower side geomembrane and the upper side geomembrane and are arranged along the geomembranes in a criss-cross manner, and the distributed piezoelectric films are electrically connected with the multi-channel impedance acquisition instrument and the multi-channel voltage acquisition instrument. The geomembrane deformation and leakage detection can be well realized, and the detection cost is reduced.

Description

Technical Field

[0001] The present invention relates to the field of piezoelectric sensing technology and anti-seepage technology, and in particular to a geomembrane deformation and leakage detection system based on a built-in piezoelectric film and a construction method. Background Art

[0002] With the acceleration of my country's urbanization process, the output of urban garbage has increased dramatically, and the growth momentum is unabated. At present, the main way to deal with urban garbage is landfill. The core of the landfill is the anti-seepage system. As a new type of flexible anti-seepage material, geomembrane has been widely used in the anti-seepage project of landfill. However, the landfill environment is complex, and geomembranes are often easily deformed and damaged due to excessive local force or uneven foundation settlement, thereby losing their anti-seepage ability. Therefore, only by accurately detecting the deformation process of the geomembrane, transmitting the detection signal in a timely manner and making early warning analysis, and timely warning of deformation and damage that may occur in actual projects, can the anti-seepage effect of the geomembrane be better realized.

[0003] The commonly used methods for geomembrane detection are electrode method, resistivity method, fiber Bragg grating, distributed optical fiber, etc. The traditional electrode method has poor accuracy and cannot grasp the stress state of the geomembrane, and cannot even accurately locate the leakage position. The most commonly used distributed optical fiber also has many disadvantages: (1) The optical fiber core is relatively fragile and requires the protection of an outer layer of steel strands; (2) Air or dust enters the flange, causing the laser to be unable to transmit and thus losing the optical fiber signal; (3) The optical fiber demodulator is relatively expensive and is monopolized by foreign technology.

[0004] Polyvinylidene fluoride polymer (PVDF) piezoelectric film is a new type of polymer piezoelectric material with the advantages of high sensitivity, fast response speed, wide frequency response range and the ability to achieve self-driving and self-sensing. Nowadays, PVDF piezoelectric film is mostly used in concrete structure health detection, and is rarely used in anti-seepage projects such as geomembrane deformation and leakage detection.

[0005] Based on this, we propose a geomembrane deformation and leakage detection system and construction method based on piezoelectric film to solve the above problems. Summary of the invention

[0006] The purpose of the present invention is to provide a geomembrane deformation and leakage detection system and construction method based on a piezoelectric film, so as to solve the problems existing in the above-mentioned prior art, realize the detection of geomembrane deformation and leakage well, and reduce the detection cost.

[0007] To achieve the above object, the present invention provides the following solutions:

[0008] The present invention provides a geomembrane deformation and leakage detection system based on a piezoelectric film, comprising a distributed piezoelectric film, a multi-channel impedance collector and a multi-channel voltage collector. The distributed piezoelectric film is pressed between a lower geomembrane and an upper geomembrane, and is arranged in a criss-cross pattern along the geomembrane. The distributed piezoelectric film is electrically connected to the multi-channel impedance collector and the multi-channel voltage collector.

[0009] Preferably, the distributed piezoelectric film includes a PVDF piezoelectric film, a silver ink electrode, a PET protective layer, a crimping terminal, a rivet and a piezoelectric film connecting wire. The silver ink electrodes are provided on both sides of the PVDF piezoelectric film, one of the silver ink electrodes is provided with a positive electrode, and the other silver ink electrode is provided with a negative electrode. The positive electrode and the negative electrode are each connected to a piezoelectric film connecting wire through a crimping terminal, and the crimping terminal is anchored to the positive electrode or the negative electrode through the rivet, and the PET protective layer is wrapped around the PVDF piezoelectric film and the silver ink electrodes on both sides.

[0010] Preferably, an overlapping area without piezoelectric film is reserved at the edge of the geomembrane for welding connection of joints of each piece of the geomembrane, and the distributed piezoelectric film is arranged in a transverse span at the joint of the geomembrane.

[0011] Preferably, the arrangement spacing of the distributed piezoelectric films in the transverse direction and the longitudinal direction is less than 0.5 meters.

[0012] Preferably, the thickness of the lower geomembrane and the upper geomembrane is not less than 0.75 mm, and the width of the geomembrane is not less than 6 m.

[0013] Preferably, the length of the distributed piezoelectric film is less than 6 m.

[0014] Preferably, the overlapping non-piezoelectric film area is reserved 0.2 m at the edge of the geomembrane.

[0015] The present invention also provides a construction method of the above-mentioned geomembrane deformation and leakage detection system based on built-in piezoelectric film, comprising the following steps:

[0016] (1) The geomembrane with built-in piezoelectric film is laid in the landfill. When laying the geomembrane with built-in piezoelectric film, the landfill reservoir area should be laid first and then the surrounding area. The wires between each geomembrane need to be marked with unit intervals, and the corresponding length of wires should be reserved for connecting the multi-channel impedance collector and the multi-channel voltage collector. After all the anti-seepage works are completed, concrete is poured above the landfill reservoir area. After the concrete hardens, clay is backfilled;

[0017] (2) Using a multi-channel impedance acquisition instrument and a multi-channel voltage acquisition instrument to collect data on the impedance and voltage of the distributed piezoelectric film;

[0018] (3) The collected data information is transmitted to the cloud platform server, and after being processed by the cloud platform, the risk level is determined and an alarm voice prompt is given.

[0019] Compared with the prior art, the present invention has achieved the following technical effects:

[0020] (1) Distributed piezoelectric film has the advantages of chemical corrosion resistance, high temperature resistance, oxidation resistance, and electromagnetic interference resistance, and can be well implemented in engineering inspections in complex environments such as landfills.

[0021] (2) Distributed piezoelectric film is a distributed detection method that integrates perception and transmission. The piezoelectric impedance and voltage effect of this technology can well reflect the state of the object being measured. In addition, the acquisition instrument is relatively cheap and low-cost, and is not subject to technology monopoly.

[0022] (3) The geomembrane based on the distributed piezoelectric film integrates the distributed piezoelectric film and the geomembrane into one, which not only realizes the function of autonomous detection, but also plays a certain "reinforcement" role, significantly improving the various performances of the geomembrane, and has great application prospects in anti-seepage engineering detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0024] Figure 1 It is a schematic diagram of the structure of the geomembrane with built-in piezoelectric film in the present invention;

[0025] Figure 2 It is a side view of the package of the distributed piezoelectric film in the present invention;

[0026] Figure 3 A top view of the package of the distributed piezoelectric film in the present invention;

[0027] Figure 4 This is a schematic diagram of the internal impedance-strain effect of the piezoelectric thin film sensing technology in the present invention;

[0028] Figure 5 This is a schematic diagram of the internal piezoelectric effect of the piezoelectric film sensing technology in the present invention;

[0029] Figure 6 This is a schematic diagram of the distributed piezoelectric film self-sensing technology in the present invention;

[0030] Figure 7It is a schematic diagram of the geomembrane deformation and leakage detection system based on piezoelectric film built-in in the present invention being applied to a landfill;

[0031] Figure 8 It is a construction process flow chart of the present invention.

[0032] In the figure: 1-distributed piezoelectric film, 2-multi-channel impedance collector, 3-multi-channel voltage collector, 4-lower geomembrane, 5-upper geomembrane, 6-geomembrane, 7-PVDF piezoelectric film, 8-silver ink electrode, 9-PET protective layer, 10-crimping terminal, 11-rivet, 12-piezoelectric film connecting wire, 13-positive electrode, 14-negative electrode, 15-landfill, 16-concrete, 17-backfill clay, 18-cold pressed terminal, 19-non-woven geotextile, 20-sand, 21-overlap, 22-viscous liquid, 23-welding, 24-data display, 25-alarm signal light, 26-GCL swelling waterproof blanket, 27-base layer. DETAILED DESCRIPTION

[0033] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0034] The purpose of the present invention is to provide a geomembrane deformation and leakage detection system and construction method based on a piezoelectric film, so as to solve the problems existing in the prior art, realize the detection of geomembrane deformation and leakage well, and reduce the detection cost.

[0035] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0036] like Figure 1-Figure 6 As shown, the present invention provides a geomembrane deformation and leakage detection system based on a piezoelectric film, including a distributed piezoelectric film 1, a multi-channel impedance collector 2 and a multi-channel voltage collector 3. The distributed piezoelectric film 1 is pressed between the lower geomembrane 4 and the upper geomembrane 5, and is arranged crisscross along the geomembrane 6. The distributed piezoelectric film 1 is electrically connected to the multi-channel impedance collector 2 and the multi-channel voltage collector 3.

[0037] In this embodiment, the distributed piezoelectric film 1 includes a PVDF piezoelectric film 7, a silver ink electrode 8, a PET protective layer 9, a crimping terminal 10, a rivet 11 and a piezoelectric film connecting wire 12. Silver ink electrodes 8 are provided on both sides of the PVDF piezoelectric film 7, one silver ink electrode 8 is provided with a positive electrode 13, and the other silver ink electrode 8 is provided with a negative electrode 14. The positive electrode 13 and the negative electrode 14 are each connected to a piezoelectric film connecting wire 12 through a crimping terminal 10, and the crimping terminal 10 is anchored to the positive electrode 13 or the negative electrode 14 through the rivet 11. The PET protective layer 9 is wrapped around the PVDF piezoelectric film 7 and the silver ink electrodes 8 on both sides.

[0038] The distributed piezoelectric film 1 is adhered to the surface of the lower geomembrane 4 with 502 strong glue, and then extruded and rolled with the upper geomembrane 5 to form an integral structure. After the geomembrane 6 (i.e., piezoelectric self-sensing geomembrane) built in the piezoelectric film is extruded and rolled, there should be no appearance defects such as bubbles, cracks, and delamination to ensure the deformation coordination of the distributed piezoelectric film 1 and the lower geomembrane 4 and the upper geomembrane 5. The piezoelectric film connecting wire 12 refers to the layout of the soft core circuit to ensure that the wire layout is clear. Finally, the cold-pressed terminal 18 is used to connect the piezoelectric film connecting wire 12 at the edge of the film to facilitate later wiring.

[0039] In this embodiment, an overlapping non-piezoelectric film area is reserved at the edge of the geomembrane 6 for welding the joints of each geomembrane 6. A distributed piezoelectric film 1 is arranged in a transverse span at the joints of the geomembrane 6 to focus on detecting the joints.

[0040] In this embodiment, in order to ensure the detection accuracy, the arrangement interval of the distributed piezoelectric film 1 in the transverse direction and the longitudinal direction is less than 0.5 meters.

[0041] In this embodiment, the thickness of the lower geomembrane 4 and the upper geomembrane 5 is not less than 0.75 mm, and the width of the geomembrane 6 is not less than 6 m.

[0042] In this embodiment, the length of the distributed piezoelectric film 1 is less than 6 m.

[0043] In this embodiment, an overlapping area without piezoelectric film is reserved for 0.2 m at the edge of the geomembrane 6 .

[0044] like Figure 7 and Figure 8 As shown, the construction method of the above-mentioned geomembrane deformation leakage detection system based on the built-in piezoelectric film comprises the following steps:

[0045] (1) The geomembrane 6 with built-in piezoelectric film is laid in the landfill 15. When laying the geomembrane 6 with built-in piezoelectric film, the landfill 15 storage area should be laid first and then the surrounding area. The wires between each geomembrane 6 need to be marked with unit intervals, and the corresponding length of wires are reserved for connecting the multi-channel impedance collector 2 and the multi-channel voltage collector 3. After all the anti-seepage works are completed, concrete 16 is poured above the landfill 15 storage area. After the concrete hardens, backfill clay 17 is laid on the concrete 16;

[0046] (2) Use the multi-channel impedance acquisition instrument 2 and the multi-channel voltage acquisition instrument 3 to collect data on the impedance and voltage of the distributed piezoelectric film 1; the sampling frequency of the multi-channel impedance acquisition instrument 2 is 1kHz, and the input voltage is 1V. When the distributed piezoelectric film 1 is subjected to external force, its impedance value changes. The range of the multi-channel voltage acquisition instrument 3 is 10V. When the distributed piezoelectric film 1 is subjected to fluctuations or vibrations, its voltage value suddenly changes. After all the geomembranes 6 built into the piezoelectric film are laid, connect the wires to the multi-channel impedance acquisition instrument 2 and the multi-channel voltage acquisition instrument 3 for data pre-collection to ensure the effectiveness of the wire connection.

[0047] (3) The collected data information is transmitted to the cloud platform server, and after being processed by the cloud platform, the risk level is determined and an alarm voice prompt is given.

[0048] Specifically, Figure 7As shown, the geomembrane 6 with built-in piezoelectric film is laid in the construction layout of the landfill. The anti-seepage measures of the landfill 15 are laid by laying the base layer 27, and then laying the GCL expanded waterproof blanket 26, the geomembrane 6 with built-in piezoelectric film, the non-woven geotextile 19, and the sand 20. When laying the geomembrane 6 with built-in piezoelectric film, it should be noted that the landfill 15 reservoir area should be laid first and then the surrounding area. The conductors between each geomembrane 6 need to be marked with unit intervals, and about 5 meters of conductors need to be reserved for connecting the multi-channel impedance collector 2 and the multi-channel voltage collector 3. During construction, the overlap 21 of each geomembrane 6 should be treated with emphasis. The overlap 21 of the upper and lower geomembranes 6 is bonded with adhesive 22, and then welded with electric welding. Distributed The piezoelectric film 1 focuses on detecting the leakage-prone position. After all the anti-seepage projects are completed, concrete 16 is poured above the landfill 15 storage area. After the concrete hardens, backfill clay 17 is laid, and the multi-channel impedance collector 2 and the multi-channel voltage collector 3 are turned on to start detecting the initial data and transmitting it to the data display 24. During the operation of the landfill, the data is continuously collected and transmitted to the data display 24. After being collected by the collector, the 4th generation mobile communication technology cloud platform wireless data transmission system is applied. Through the combination of the 32-bit microcontroller embedded system and the 4G module, the collected data information is transmitted to the cloud platform server through the Internet network. After the cloud platform data is processed, the risk level is delineated and an alarm voice prompt is given. The risk level judgment standard is: according to the change interval of the four characteristic parameter indicators, the risk level of the geomembrane built in the distributed piezoelectric film is divided into four levels: no risk, low risk, high risk and ultra-high risk. In addition, the alarm signal light 25 can emit white, green, yellow and red respectively according to the signal transmission of the risk level module. When the risk level reaches "high risk", an alarm voice prompt is issued.

[0049] The intrinsic mechanism of distributed piezoelectric film 1 detection, (1) impedance-strain effect, such as Figure 4 As shown, the inside of the piezoelectric film is equivalent to a combination of a resistor and a capacitor in parallel. When the piezoelectric film is subjected to external force, a 1kHz simple harmonic voltage excitation is applied to it, and the electromechanical impedance of the piezoelectric film itself is calculated by detecting the weak current in the circuit. The measured impedance is compared with the impedance in the initial state to quantify the strain of the geomembrane. (2) Piezoelectric effect, such as Figure 5 As shown, when the piezoelectric film is subjected to external force, it will undergo a slight deformation and generate positive and negative charges on the inner and outer surfaces respectively. When the external force is removed, the charges will dissipate immediately. This conversion of mechanical energy into electrical energy is called the "positive piezoelectric effect."

[0050] The present invention utilizes the sensitivity of piezoelectric film to stress, strain, vibration and fluctuation, and collects the impedance value of distributed piezoelectric film through a multi-channel piezoelectric impedance collector. When subjected to stress and strain, its impedance value changes. The change in impedance value is analyzed and a corresponding relationship is established with the stress and strain. The voltage signal value of the distributed piezoelectric film is collected through a multi-channel piezoelectric voltage collector. When subjected to external disturbance and vibration or fluctuation, its voltage signal suddenly changes. The corresponding leakage position is determined based on the voltage sudden change position analysis.

[0051] The present invention uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only used to help understand the method and core ideas of the present invention. At the same time, for those skilled in the art, according to the ideas of the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A geomembrane deformation and leakage detection system based on piezoelectric film, characterized in that: It includes a distributed piezoelectric film, a multi-channel impedance collector and a multi-channel voltage collector. The distributed piezoelectric film is pressed between the lower geomembrane and the upper geomembrane, and is arranged crisscross along the geomembrane. The distributed piezoelectric film is electrically connected to the multi-channel impedance collector and the multi-channel voltage collector.

2. The geomembrane deformation and leakage detection system based on piezoelectric film built-in according to claim 1 is characterized by: The distributed piezoelectric film includes a PVDF piezoelectric film, a silver ink electrode, a PET protective layer, a crimping terminal, a rivet and a piezoelectric film connecting wire. The silver ink electrodes are provided on both sides of the PVDF piezoelectric film, one of the silver ink electrodes is provided with a positive electrode, and the other silver ink electrode is provided with a negative electrode. The positive electrode and the negative electrode are each connected to a piezoelectric film connecting wire through a crimping terminal. The crimping terminal is anchored to the positive electrode or the negative electrode through the rivet, and the PET protective layer is wrapped around the PVDF piezoelectric film and the silver ink electrodes on both sides.

3. The geomembrane deformation and leakage detection system based on piezoelectric film built-in according to claim 1 is characterized in that: An overlapping area without piezoelectric film is reserved at the edge of the geomembrane for welding the joints of each piece of the geomembrane, and the distributed piezoelectric film is arranged in a transverse span at the joint of the geomembrane.

4. The geomembrane deformation and leakage detection system based on built-in piezoelectric film according to claim 1 is characterized in that: The arrangement spacing of the distributed piezoelectric films in the transverse direction and the longitudinal direction is less than 0.5 meters.

5. The geomembrane deformation and leakage detection system based on built-in piezoelectric film according to claim 1 is characterized in that: The thickness of the lower geomembrane and the upper geomembrane is not less than 0.75 mm, and the width of the geomembrane is not less than 6 m.

6. The geomembrane deformation and leakage detection system based on built-in piezoelectric film according to claim 1 is characterized by: The length of the distributed piezoelectric film is less than 6m.

7. The geomembrane deformation and leakage detection system based on built-in piezoelectric film according to claim 3 is characterized by: The overlapping non-piezoelectric film area is reserved 0.2m at the edge of the geomembrane.

8. A construction method of a geomembrane deformation and leakage detection system based on a piezoelectric film as claimed in any one of claims 1 to 7, characterized in that: The following steps are involved: (1) The geomembrane with built-in piezoelectric film is laid in the landfill. When laying the geomembrane with built-in piezoelectric film, the landfill reservoir area should be laid first and then the surrounding area. The wires between each geomembrane need to be marked with unit intervals, and the corresponding length of wires should be reserved for connecting the multi-channel impedance collector and the multi-channel voltage collector. After all the anti-seepage works are completed, concrete is poured above the landfill reservoir area. After the concrete hardens, clay is backfilled; (2) Using a multi-channel impedance acquisition instrument and a multi-channel voltage acquisition instrument to collect data on the impedance and voltage of the distributed piezoelectric film; (3) The collected data information is transmitted to the cloud platform server, and after being processed by the cloud platform, the risk level is determined and an alarm voice prompt is given.

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