A steel sheet pile water level monitoring device based on capacitance detection

Abstract

The application discloses a kind of steel sheet pile water level monitoring devices based on capacitance detection, adopt steel sheet pile body (2) as first common electrode, insulating layer (6) is arranged on the inner side surface of steel sheet pile, and long strip auxiliary electrode plate (3) is vertically fixed in the inner side of insulating layer (6), so that the two parallel arrangements form a coupled capacitance sensitive structure, realize the integration of monitoring device and steel sheet pile integration;At the same time, the ceramic capacitor sensor is set at the warning water level and the dangerous water level height, and the water level monitoring alarm is realized by using the dielectric constant difference between water and air.The application does not need to punch and arrange, and there is no mechanical moving part, which effectively solves the problem that the traditional water level monitoring equipment installation is easy to damage the structure and cannot be integrated, and is suitable for high turbidity and high impurity foundation pit environment.

Description

Technical Field

[0001] This invention belongs to the field of geotechnical engineering monitoring technology, and relates to water level monitoring, specifically to a steel sheet pile water level monitoring device based on capacitance detection. Background Technology

[0002] Steel sheet piles are widely used in foundation pit support due to their advantages such as quick construction and reusability. However, the safety of foundation pit projects depends not only on the strength of the support structure but also on changes in the groundwater level. Fluctuations in the groundwater level directly affect the foundation pit's heave stability and seepage stability, while also causing displacement and deformation of the surrounding soil, posing a critical constraint on the overall safety of the foundation pit and the stability of the surrounding environment.

[0003] Currently, commonly used water level monitoring methods in foundation pit engineering mainly include float-type water level gauges, pressure-type water level gauges, and ultrasonic water level gauges. However, these traditional monitoring methods have significant limitations in the application of sheet pile foundation pits: Installation is complex and structurally damaging: Traditional methods usually require the separate installation of logging wells in the foundation pit or drilling holes in the structure for installation, which is not only cumbersome but may also damage the water-stopping performance or structural integrity of the steel sheet piles.

[0004] Poor environmental adaptability: The environment of the foundation pit is usually harsh, containing a large amount of silt and debris. Float-type and ultrasonic equipment are easily affected by silt accumulation and debris entanglement, leading to distorted monitoring data or equipment jamming.

[0005] Low integration: Existing monitoring equipment is mostly an independent system that cannot be integrated with the sheet pile body, making it difficult to deploy flexibly in a narrow foundation pit space, and the maintenance cost is high.

[0006] Therefore, there is an urgent need to develop a new type of water level monitoring device that can be closely integrated with sheet piles to solve the above problems and achieve real-time, accurate, and maintenance-free monitoring of the water level in the foundation pit. Summary of the Invention

[0007] To address the shortcomings of existing technologies, this invention provides a sheet pile water level monitoring device based on capacitance detection. The device employs a sheet pile body 2 as the first electrode, covers the inner surface of the sheet pile with an epoxy resin insulating layer 6, and fixes a vertically elongated auxiliary electrode plate 3 inside the epoxy resin insulating layer 6. This design allows the auxiliary electrode plate 3 to be arranged parallel to the sheet pile body 2, forming a coupled capacitance-sensitive structure. This achieves integrated sensor-support structure integration without additional space occupation. By installing ceramic capacitance sensors at preset heights such as warning and danger water levels, the device utilizes the significant difference in dielectric constant between water (dielectric constant approximately 80) and air (dielectric constant approximately 1). When the water level reaches the preset height, a sudden change in dielectric constant triggers an early warning signal, eliminating the need for any moving mechanical parts. This solves the problem of traditional float-type and ultrasonic devices being susceptible to data distortion or equipment jamming due to siltation and debris entanglement in harsh foundation pit environments.

[0008] To achieve the above objectives, the present invention adopts the following technical solution: A sheet pile water level monitoring device based on capacitance detection includes a sheet pile body 2, an auxiliary electrode plate 3, a signal processing and transmission module, and a power supply module for powering the entire device. An insulating layer 6 is provided on the inner surface of the sheet pile body 2, and the auxiliary electrode plate 3 is disposed on the inner surface of the insulating layer 6. The auxiliary electrode plate 3 and the sheet pile body 2 are arranged parallel to each other, and the two cooperate to form a coupled capacitance-sensitive structure. The sheet pile body 2 and the auxiliary electrode plate 3 are electrically connected to the signal processing and transmission module via wires to achieve real-time water level monitoring.

[0009] Furthermore, the auxiliary electrode plate 3 is fixed to the inner surface of the insulating layer 6 by insulating fasteners or high-strength adhesive.

[0010] Furthermore, the auxiliary electrode plate 3 is a single continuous vertical strip of metal plate, the length of which is consistent with the height of the sheet pile body 2, and the length covers the entire effective water level monitoring range from the bottom of the foundation pit to the top of the sheet pile body 2; the width is set to 50mm~200mm.

[0011] Furthermore, the insulating layer 6 is made of epoxy resin and is tightly attached to the inner surface of the sheet pile body 2 by coating or casting, with a thickness of 2mm to 5mm.

[0012] Furthermore, the signal processing and transmission module includes a data acquisition module and a wireless transmission terminal. The data acquisition module adopts a general-purpose data acquisition instrument with multi-channel AI / DI access capability. The steel sheet pile body 2 is connected to the grounding terminal of the data acquisition instrument through a wire. The auxiliary electrode plate 3 is connected to an independent capacitor-to-voltage conversion circuit through a wire. After linearly converting the capacitance change into a standard voltage or current signal, it is connected to the analog input interface of the data acquisition instrument.

[0013] Furthermore, the data acquisition device integrates a central processing unit, which has a pre-set data processing program that embeds a water level inverse calculation formula. in: The total capacitance of the coupled capacitor-sensitive structure is measured by a general-purpose data acquisition instrument through a capacitance-to-voltage conversion circuit. The vacuum permittivity, The width of auxiliary electrode plate 3, This refers to the electrode spacing, which is equivalent to the thickness of the insulating layer 6. is the relative permittivity of air. Let H be the relative permittivity of water, and H be the total height of the auxiliary electrode plate 3.

[0014] Furthermore, the data acquisition device is encapsulated in a stainless steel waterproof junction box 1 with an IP67 protection rating.

[0015] Furthermore, the water level monitoring device also includes an early warning sensing component, which is fixed to the inner surface of the insulating layer 6 by an insulating bracket or an insulating clamp.

[0016] Furthermore, the early warning sensing component includes a warning water level sensor 4 and a danger water level sensor 5, both of which are non-contact ceramic capacitive sensors with their sensing surfaces facing the water body inside the steel sheet pile. The signal output terminals of the water level sensor 4 and the danger water level sensor 5 are respectively connected to two independent switch input interfaces of the data acquisition module via wires to achieve graded alarms.

[0017] Furthermore, all the conductors are double-shielded corrosion-resistant cables, with an internal double shielding layer of aluminum foil Mylar and tinned copper mesh, and an outer extruded polyurethane or nylon sheath.

[0018] Compared with the prior art, the present invention has the following beneficial effects: 1. This invention directly uses the steel sheet pile body 2 as a common electrode, without the need for additional drilling, thus avoiding damage to the support structure. It has a high degree of structural integration, is easy to install, and can be adapted to foundation pit engineering scenarios with limited space and complex working conditions.

[0019] 2. This invention uses a ceramic capacitive sensor to achieve non-contact water level detection. It relies on the difference in dielectric constant between water and air to sense changes in water level. When the water level reaches a preset height, the dielectric constant changes abruptly, thereby triggering an early warning signal. There are no mechanical moving parts, which fundamentally solves the defects of traditional float-type water level gauges that are prone to jamming and ultrasonic equipment that is easily interfered with by silt and debris. It can be stably applied to the water environment of foundation pits with high turbidity and high impurities.

[0020] 3. The invention adopts a full capacitive detection mechanism, with no mechanical wear and loss; coupled with an IP67 protective shell and corrosion-resistant shielded cables, it can adapt to underground humid and corrosive environments, eliminating the need for frequent manual cleaning and maintenance, and effectively extending the service life of the device.

[0021] 4. This invention uses a parallel plate capacitor structure to sense dynamic changes in water level in real time and linearly, and combines it with a wireless transmission module to achieve accurate early warning of water level classification. The device is simple to deploy and easy to construct, which greatly reduces the construction difficulty and overall operation and maintenance cost of foundation pit water level monitoring. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the overall structure of a steel sheet pile water level monitoring device based on capacitance detection according to the present invention. Figure 2 for Figure 1 Middle AA section view; Figure 3 This is a schematic diagram showing the installation location of the early warning sensing component in this invention; Figure 4 This is a block diagram illustrating the control principle of a steel sheet pile water level monitoring device system based on capacitance detection, according to the present invention.

[0023] In the diagram: 1-Waterproof junction box, 2-Sheet pile body, 3-Auxiliary electrode plate, 4-Warning water level sensor, 5-Danger water level sensor, 6-Insulation layer, 7-Riverbed / foundation, 8-Normal water level line, 9-Warning water level line, 10-Danger water level line. Detailed Implementation

[0024] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0025] The present invention discloses a steel sheet pile water level monitoring device based on capacitance detection, comprising a coupled capacitance sensitive structure and a signal processing and transmission module.

[0026] like Figure 1 , Figure 2As shown, the coupling capacitance sensitive structure includes a sheet pile body 2. An insulating layer 6 is provided on the inner surface of the sheet pile body 2. An auxiliary electrode plate 3 is fixed to the inner surface of the insulating layer 6 by insulating fasteners or high-strength adhesive. The auxiliary electrode plate 3 is arranged parallel to the sheet pile body 2 and is a single continuous vertical strip of metal plate. Its length direction is consistent with the height direction of the sheet pile body 2, covering the entire effective water level monitoring range from the bottom of the pit to the top of the sheet pile body 2. Its width is set to 50mm~200mm to ensure sufficient capacitance sensing area. The thickness of the insulating layer 6, i.e., the electrode spacing between the auxiliary electrode plate 3 and the sheet pile body 2, is controlled at 2mm~5mm to ensure the sensitivity of capacitance sensing and structural stability. The insulating layer 6 is preferably made of epoxy resin, which is tightly adhered to the surface of the sheet pile body 2 through coating or casting processes. The function of the insulating layer 6 is to ensure reliable electrical insulation between the sheet pile body 2 and the auxiliary electrode plate 3, preventing short circuits. The sheet pile body 2 serves as the first electrode, with its lead wire connected to the grounding terminal of the signal processing and transmission module. The auxiliary electrode plate 3 serves as the second electrode (signal sensing electrode), connected to the analog input interface of the signal processing and transmission module. The sheet pile body 2, the insulation layer 6, and the auxiliary electrode plate 3 together constitute a parallel plate capacitor structure, i.e., a coupled capacitor-sensitive structure. When the water level in the foundation pit changes, the height of the auxiliary electrode plate 3 submerged by water changes accordingly. Since the sheet pile body 2 and the auxiliary electrode plate 3 constitute a parallel plate capacitor, their total capacitance can be considered as the parallel superposition of the capacitance of the submerged part and the air-filled part. Let the total height of the auxiliary electrode plate 3 be H, and the submerged height, i.e., the current water level height, be H. According to the principle of parallel-plate capacitors, the total capacitance of this coupled capacitor-sensitive structure is... It can be represented as: in: The total capacitance of the coupled capacitor-sensitive structure is measured by a general-purpose data acquisition instrument through a capacitance-to-voltage conversion circuit. The vacuum permittivity, The width of auxiliary electrode plate 3, The distance between the plates is the thickness of the insulating layer 6. It is the relative permittivity of air (approximately equal to 1). It is the relative permittivity of water (approximately 80).

[0027] Taking typical engineering parameters as an example: If the auxiliary electrode plate width W = 100 mm, the electrode plate spacing d = 3 mm, and the total electrode plate height H = 1000 mm (i.e., the monitoring range is 1 meter), when the water level is at its lowest (i.e., h = 0, and the medium between the electrodes is air), the initial capacitance... When the water level rises to the top of the electrode plates (i.e., h = H = 1000 mm, the plates are completely submerged), the capacitor... Therefore, the capacitance variation range ΔC of this coupled capacitor-sensitive structure is approximately 295 pF to 23.6 nF. Adjusting the plate width, spacing, or height will change the absolute value of the capacitance accordingly, but the overall magnitude remains within the picofarad to nanofarad range, falling entirely within the mature measurement range of existing capacitance detection technologies.

[0028] With a fixed electrode structure, the total capacitance C is linearly related to the water immersion height h; as the water level rises, the water immersion height... As the relative permittivity of water increases, it gradually replaces the relative permittivity of air, increasing the effective permittivity between the electrode plates and thus the coupling capacitance. This increases accordingly. The signal processing module detects the capacitance value. The current real-time water level can be calculated from the changes in the water level. .

[0029] This design directly utilizes the existing sheet pile body 2 as the electrode, eliminating the need to drill holes in the pile body, thus preserving the water-stopping performance and structural integrity of the sheet pile, and achieving "zero space occupation" fusion of the sensor and the support structure.

[0030] To provide dual safety assurance, the sheet pile water level monitoring device based on capacitance detection of this invention is also equipped with an early warning sensing component, such as... Figure 1 , Figure 3 As shown, to clearly illustrate the water level classification system, Figure 3The diagram also shows the riverbed / foundation 7 where the sheet pile 2 is located, the normal water level 8, and the preset warning water level 9 and danger water level 10. The early warning sensing assembly includes a warning water level sensor 4 and a danger water level sensor 5. Both sensors are non-contact ceramic capacitive sensors, arranged side-by-side with the auxiliary electrode plate 3 without overlapping. They are fixed to the surface of the insulating layer 6 on the inner wall of the sheet pile using an insulating bracket or insulating clamp, ensuring electrical isolation between the sensor and the sheet pile body 2. The sensor sensing surface faces the water body inside the sheet pile. The warning water level sensor 4 is installed at the preset warning water level 9; the danger water level sensor 5 is installed at the preset danger water level 10. According to the engineering safety design requirements, the warning water level line 9 is set 50mm~100mm below the highest designed water level of the foundation pit (i.e., 50~100mm below the highest water level); the danger water level line 10 is set at the highest designed water level of the foundation pit, or at the critical water level that may cause sudden surges, quicksand, or other hazards, depending on the engineering hydrogeological conditions. When the water level rises and touches the sensor's sensing surface, the electric field distribution at the sensor's front end changes significantly due to the intervention of water, thereby triggering a switching signal. It should be noted that the brackets or clamps used to fix the warning water level sensor 4 and the danger water level sensor 5 must be made of insulating materials (such as nylon, polytetrafluoroethylene, or epoxy resin, etc.). If conductive materials such as metal are used for the brackets, an unexpected conductive path or parasitic capacitance will be introduced between the sheet pile body 2 and the sensor, interfering with the sensor's own electric field distribution, causing the switching signal to be falsely triggered or fail, thus compromising the reliability of the non-contact ceramic capacitor early warning mechanism. The use of insulating brackets ensures that the sensor only responds to changes in the dielectric constant of the water, guaranteeing the accuracy of the early warning function. This mechanism has no moving mechanical parts, completely solving the problems of traditional float-type devices being easily jammed by silt accumulation and ultrasonic devices being easily interfered with by debris on the water surface. Even in harsh environments such as pits and turbid water, it can achieve maintenance-free and accurate point-based alarms.

[0031] The signal processing and transmission module is the data processing hub of the sheet pile water level monitoring device based on capacitance detection in this invention. This module includes a data acquisition module and a wireless transmission terminal. The data acquisition module uses existing general-purpose monitoring data acquisition equipment for geotechnical engineering safety. For example, general-purpose data acquisition instruments with multi-channel AI / DI access capabilities from companies such as Geokon and NARI can be selected. These instruments integrate multi-channel signal conditioning circuits, multi-channel analog-to-digital converters (ADCs), and a central processing unit, eliminating the need for customized circuit design for this device. The data acquisition instrument is encapsulated in a stainless steel waterproof junction box 1 with an IP67 protection rating, providing complete dustproof and short-term immersion protection, ensuring the dryness and safety of the internal circuitry during rainy seasons or in high-humidity environments.

[0032] like Figure 4 As shown, the sheet pile body 2 serves as the common electrode, connected to the grounding terminal (GND) of the data acquisition instrument via a wire to ensure a complete capacitance detection loop. The auxiliary electrode plate 3 leads out a wire as the signal output terminal, connected to an independent capacitance-to-voltage (C / V) conversion circuit via a double-shielded corrosion-resistant cable. This circuit linearly converts the capacitance change into a standard voltage or current signal, which is then connected to the analog input interface (AI) of the data acquisition instrument. This C / V conversion circuit is encapsulated within an IP67-rated stainless steel waterproof junction box 1 at the top of the sheet pile. As a preferred example, the capacitance-to-voltage conversion circuit can use a general-purpose capacitance detection integrated circuit chip, such as the CAV424 (Analog Microelectronics GmbH), with a typical measurement range of 0.5 pF to 1 nF; or it can use the Minyuan Sensing LLM series non-contact liquid level sensing module, with a default capacitance measurement range of 0–100 pF, a maximum resolution of 0.001 pF, and customizable up to a 10 nF range. The output of this C / V conversion circuit is a standard voltage signal (e.g., 0-5V or 0-10V), which can be directly connected to the analog input channel of the data acquisition instrument. It should be noted that while the analog input channel of the data acquisition instrument (including but not limited to products from brands such as Jikang and NARI) cannot directly detect capacitance signals, it widely supports standard voltage signal inputs of 0-±5V or 0-±10V. By setting an independent C / V conversion circuit in the IP67 waterproof junction box at the top of the sheet pile, the capacitance change of the coupled capacitor-sensitive structure is converted into a standard voltage signal before being input to the acquisition instrument, thus achieving complete acquisition and processing of water level change signals. This acquisition method is a conventional technique in this field and requires no special modification or customized circuit design to the acquisition instrument. The multi-channel analog-to-digital conversion unit inside the data acquisition instrument converts the voltage / current analog signal into a digital quantity for the central processing unit to calculate the water level height. The central processing unit has a pre-set data processing program that embeds a water level inverse calculation formula, which can calculate the current water level height in real time from the digital quantity acquired by the AI ​​channel. The water level inverse calculation formula is as follows: in: The total capacitance of the coupled capacitor-sensitive structure is measured by a general-purpose data acquisition instrument through a capacitance-to-voltage conversion circuit. The vacuum permittivity, The width of auxiliary electrode plate 3, The electrode spacing (i.e., the thickness of the insulating layer (6)) It is the relative permittivity of air (approximately equal to 1). H is the relative permittivity of water (approximately 80), and H is the total height of the auxiliary electrode plate 3.

[0033] The signal output terminals of the warning water level sensor 4 and the danger water level sensor 5 are respectively connected to the independent digital input (DI) interfaces of the data acquisition instrument via double-shielded corrosion-resistant cables. When the water level submerges a sensor, the internal circuit of the sensor generates a high-low level transition. The data acquisition instrument determines whether to trigger a graded alarm by real-time monitoring the level status of the corresponding DI port.

[0034] Afterwards, the data acquisition instrument packages the processed real-time water level data and switch alarm status data together and uploads them to the remote monitoring terminal via an external wireless transmission terminal (such as a 4G / NB-IoT module) connected to the communication interface, completing the data transmission. The wireless transmission terminal is installed on top of the sheet piles or in an unobstructed safe area to ensure effective signal coverage.

[0035] This invention relates to a sheet pile water level monitoring device based on capacitance detection, equipped with an independent power supply module, preferably a high-capacity rechargeable lithium battery pack or an external solar power adapter, to support long-term unattended operation in field environments. The power output terminal of the power supply module is connected to the power input terminal of the independent capacitor-to-voltage conversion circuit of the data acquisition instrument via a waterproof power cable, providing a stable operating voltage for both. The connecting cables between the power supply module and other components also use double-shielded corrosion-resistant cables. The internal shielding layer of the cable is composed of aluminum foil Mylar and tinned copper mesh, effectively suppressing complex electromagnetic interference (EMI) around the sheet pile. The outer layer of the cable is extruded with polyurethane (PUR) or nylon corrosion-resistant sheath, possessing excellent acid and alkali resistance, wear resistance, and tensile strength, and is housed in an IP67 waterproof junction box to ensure electrical safety and long-term reliability in humid environments.

[0036] The specific workflow of this device is as follows: Under normal monitoring conditions, the data acquisition instrument periodically reads the capacitance value changes of the coupling capacitor sensitive structure through the AI ​​channel according to the preset sampling frequency (e.g., once every 10 minutes), thereby calculating the current real-time water level height, and uploading the data to the remote monitoring terminal for display and storage.

[0037] Simultaneously, the DI channel of the general-purpose data acquisition instrument monitors the status of the ceramic capacitive sensor in real time. Once the water level rises and touches the danger or warning water level line, the ceramic capacitive sensor at the corresponding location is triggered, and the corresponding DI channel detects a change in the signal level (e.g., from low to high). The general-purpose data acquisition instrument immediately determines this as an "exceeding danger level" or "exceeding warning level" event and prioritizes sending an alarm command to the remote monitoring terminal, achieving a dual-protection water level monitoring function. This invention utilizes the principle of capacitance detection to achieve integrated, non-contact, and intelligent water level monitoring of sheet piles, possessing high engineering application value. By deeply integrating the sensor with the sheet pile body 2, real-time monitoring and graded early warning of groundwater levels in the foundation pit are achieved.

Claims

1. A sheet pile water level monitoring device based on capacitance detection, characterized in that, The device includes a sheet pile body (2), an auxiliary electrode plate (3), a signal processing and transmission module, and a power supply module for powering the entire device. An insulating layer (6) is provided on the inner surface of the sheet pile body (2), and the auxiliary electrode plate (3) is disposed on the inner surface of the insulating layer (6). The auxiliary electrode plate (3) and the sheet pile body (2) are arranged in parallel and cooperate to form a coupling capacitor sensitive structure. The sheet pile body (2) and the auxiliary electrode plate (3) are electrically connected to the signal processing and transmission module through wires to realize real-time monitoring of water level.

2. The sheet pile water level monitoring device based on capacitance detection according to claim 1, characterized in that, The auxiliary electrode plate (3) is fixed to the inner surface of the insulating layer (6) by insulating fasteners or high-strength adhesive.

3. The sheet pile water level monitoring device based on capacitance detection according to claim 1, characterized in that, The auxiliary electrode plate (3) is a single continuous vertical strip of metal plate. Its length direction is consistent with the height direction of the sheet pile body (2). Its length covers the entire effective water level monitoring range from the bottom of the pit to the top of the sheet pile body (2). The width is set to 50mm~200mm.

4. The sheet pile water level monitoring device based on capacitance detection according to claim 1, characterized in that, The insulating layer (6) is an epoxy resin material, which is tightly attached to the inner surface of the sheet pile body (2) by coating or casting, and has a thickness of 2mm to 5mm.

5. The sheet pile water level monitoring device based on capacitance detection according to claim 1, characterized in that, The signal processing and transmission module includes a data acquisition module and a wireless transmission terminal. The data acquisition module adopts a general-purpose data acquisition instrument with multi-channel AI / DI access capability. The steel sheet pile body (2) is connected to the grounding terminal of the data acquisition instrument through a wire. The auxiliary electrode plate (3) is connected to an independent capacitor-voltage conversion circuit through a wire. After the capacitance change is linearly converted into a standard voltage or current signal, it is connected to the analog input interface of the data acquisition instrument.

6. The sheet pile water level monitoring device based on capacitance detection according to claim 5, characterized in that, The data acquisition device integrates a central processing unit, which has a pre-set data processing program that embeds a water level inverse calculation formula. in: The total capacitance of the coupled capacitor-sensitive structure is measured by a general-purpose data acquisition instrument through a capacitance-to-voltage conversion circuit. The vacuum permittivity, The width of the auxiliary electrode plate (3) The distance between the plates is the same as the thickness of the insulating layer (6). is the relative permittivity of air. H is the relative permittivity of water, and H is the total height of the auxiliary electrode plate (3).

7. The sheet pile water level monitoring device based on capacitance detection according to claim 6, characterized in that, The data acquisition instrument is encapsulated in a stainless steel waterproof junction box (1) with an IP67 protection rating.

8. The sheet pile water level monitoring device based on capacitance detection according to claim 7, characterized in that, The water level monitoring device also includes an early warning sensing component, which is fixed to the inner surface of the insulating layer (6) by an insulating bracket or an insulating clamp.

9. The sheet pile water level monitoring device based on capacitance detection according to claim 8, characterized in that, The early warning sensing component includes a warning water level sensor (4) and a danger water level sensor (5). Both of them are non-contact ceramic capacitive sensors with the sensing surface facing the water body inside the steel sheet pile. The signal output terminals of the water level sensor (4) and the danger water level sensor (5) are respectively connected to two independent switch input interfaces of the data acquisition instrument via wires to realize graded alarm.

10. The sheet pile water level monitoring device based on capacitance detection according to any one of claims 1-9, characterized in that, All conductors are double-shielded corrosion-resistant cables. The cables have an internal double shielding layer of aluminum foil Mylar and tinned copper mesh, and an outer extruded polyurethane or nylon sheath.

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