A system for monitoring the moisture content of slope soil based on piezoelectric intelligent aggregate

Abstract

The invention discloses a system for monitoring the moisture content of slope soil based on piezoelectric intelligent aggregate, comprising a computer, an NI data acquisition and analysis system, a power amplifier, a piezoelectric intelligent aggregate sensor, a sliding slope, a sliding bed, a slope body, a piezoelectric ceramic sheet and an electric conductor. The invention relates to the technical field of a long-term online monitoring method for the moisture content of soil slopes. The system for monitoring the moisture content of slope soil based on piezoelectric intelligent aggregates forms a set of easy-to-use, economical and efficient moisture content data acquisition and analysis processing system, and combines with Labview, Matlab and other related processing software to perform long-term real-time online monitoring of the moisture content of soil slopes, realizes long-term, online, remote and rapid monitoring of the moisture content inside the soil slopes, can accurately evaluate the moisture content of each key position inside the soil slopes, has a fast response speed and the whole system has good stability and durability.

Description

Technical Field

[0001] The invention relates to the technical field of long-term online monitoring methods for soil slope moisture content, and in particular to a system for monitoring slope soil moisture content based on piezoelectric intelligent aggregates. Background Art

[0002] The deep water content of the slope is one of the basic parameters for evaluating the stability of soil slopes, and it is also a basic physical quantity for evaluating the engineering properties of slope soil. Many studies have shown that the size of the soil water content has a very important impact on geological disasters such as slope instability and sliding, large-scale collapse and landslides. At present, there are many methods used to determine the water content of the soil. According to their different characteristics and application scope, they can be divided into local methods and regional methods. The local method is mainly through indoor tests and some on-site original point measurement methods, such as drying method, resistivity method, time domain reflection method, ground penetrating radar method and frequency domain reflection method. The regional method is to grasp and determine the water content of the entire slope soil as a whole through some macroscopic methods, such as infrared sensing method, remote sensing imaging method and spectral analysis method. Due to sensor technology and other reasons, slope water content monitoring has always been a recognized problem at home and abroad, and the measurement results of the internal water content of the slope by different methods are also quite different.

[0003] Most of the local measurement methods mentioned above are suitable for use in laboratories, and they are all point measurements. They cannot continuously obtain the moisture content of the soil deep in the slope, which limits their application in slope stability analysis and landslide monitoring and early warning. The regional method can only make a rough estimate of the overall moisture content of the soil on the surface of the slope, and cannot achieve accurate measurement. Chen Zhuo from Nanjing University coupled hydrophilic rubber with optical fiber, and used FBG optical fiber sensing technology to obtain the moisture content of the soil by measuring the deformation of the optical fiber. This method is reliable when the moisture content is low, but the test accuracy is difficult to guarantee under conditions of higher moisture content. In addition, the optical fiber sensor is placed deep in the soil slope for a long time. Affected by harsh environmental conditions, its measurement characteristic value will drift, affecting its measurement accuracy. Summary of the invention

[0004] 1. Technical issues to be solved

[0005] In view of the deficiencies in the prior art, the present invention provides a system for monitoring the moisture content of slope soil based on piezoelectric intelligent aggregate, which solves the problem of low accuracy in the existing monitoring of the moisture content of slope soil.

[0006] (II) Technical solution

[0007] To achieve the above-mentioned purpose, the present invention provides the following technical solution: a system for monitoring the moisture content of slope soil based on piezoelectric intelligent aggregate, comprising a computer, an NI data acquisition and analysis system, a power amplifier, a piezoelectric intelligent aggregate sensor, a sliding slope, a sliding bed, a slope body, a piezoelectric ceramic sheet and an electric conductor.

[0008] The NI data acquisition and analysis system is externally connected to a computer, and the NI data acquisition and analysis system is electrically connected to a power amplifier.

[0009] A slope body is arranged on the sliding slope surface of the slide bed. A plurality of piezoelectric intelligent aggregate sensors are built in the slope body. The piezoelectric intelligent aggregate sensors are electrically connected to the NI data acquisition and analysis system and the power amplifier respectively.

[0010] The piezoelectric intelligent aggregate sensor comprises a piezoelectric ceramic sheet and an electric wire for connecting with an external electrical component.

[0011] Preferably, the method for monitoring moisture content comprises the following steps: Step (1) burying the piezoelectric intelligent aggregate sensor in the deep part of the slope body at a position where the moisture content of the soil needs to be monitored, and maintaining the directionality and position accuracy of the piezoelectric intelligent aggregate sensor during burying.

[0012] Step (2) Connect the relevant equipment in the monitoring system, turn on the power supply and turn on the instrument switch, and excite the piezoelectric intelligent aggregate sensor with a high-frequency excitation signal through the NI data acquisition and analysis system. The sweep signal frequency is 100-150KHz, the amplitude is 3V, and the period is 1s;

[0013] Step (3) Based on the inverse piezoelectric effect of the piezoelectric smart material, the piezoelectric smart aggregate sensor converts the electrical signal into a stress wave signal. After the piezoelectric smart aggregate sensors installed at different positions in the slope body receive the stress wave signal, based on the direct piezoelectric effect of the piezoelectric smart material, the signal is converted back into an electrical signal and collected and stored by the NI data acquisition and analysis system.

[0014] Step (4) establishes a functional relationship between the stress wave signal received by the piezoelectric intelligent aggregate sensor and the moisture content of the slope soil based on the amplitude, energy, mode, wave velocity, propagation path and propagation time of the stress wave signal propagated inside the slope, and then determines the moisture content at different positions of the slope.

[0015] Preferably, in step (2), a high-frequency and high-voltage signal amplifier is used to amplify the excitation signal.

[0016] Preferably, before performing step (4), the received stress wave signal is first filtered and subjected to noise reduction processing.

[0017] Preferably, in step (2), the high-frequency signal excited by the piezoelectric intelligent aggregate sensor through the NI data acquisition and analysis system is a sine frequency sweep wave.

[0018] Preferably, in step (4), the amplitude, energy, mode, wave velocity, propagation path and propagation time of the stress wave signal received by the sensor and propagated inside the slope are compared with the system test calibration to determine the moisture content at different locations inside the soil slope.

[0019] Preferably, the system test calibration comprises the following steps:

[0020] Step (I): Collect representative soil samples from the soil slope to be monitored and place them in a drying oven to fully dry until they are completely dry and the mass of the soil sample no longer decreases;

[0021] Step (II): Take out the soil sample and weigh it to obtain the mass of the soil sample in a completely dry state as m1. At this time, the moisture content of the soil is 0%;

[0022] Step (III): Stir and mix the completely dried soil sample with the same mass of water, and use a mold to make a soil slope specimen. At this time, the initial moisture content of the slope specimen is 100%. Before making the slope specimen, a piezoelectric intelligent aggregate sensor is pre-buried at a specific position inside the soil slope specimen. The two sensors are separated by a certain distance, which is consistent with the sensor spacing in the soil slope to be monitored. To ensure the stability and reliability of the test results, the number of specimens is three groups;

[0023] Step (IV): using the monitoring system of the present invention and the wave method in the active sensing method, stress wave signal detection is performed on three groups of soil slope specimens to obtain waveform information of received stress waves when the initial water content is 100%;

[0024] Step (V) Calibration of relative moisture content: Place the soil slope specimen on a digital balance and place it in a 40°C constant temperature box to dry it and lose water. The evaporation amount of moisture in the soil slope specimen is obtained according to the reading of the balance, weighed and recorded as mi, and then the moisture content of the specimen is calculated. Stress wave signal detection is performed at this moisture content to obtain stress wave information under different relative moisture content conditions; for each working condition, a single pulse wave with a sinusoidal sweep frequency of 100 to 150KHz is used for testing; the sweep wave is used to compare the differences in the received stress wave signals under different moisture content conditions, and the relevant moisture content evaluation index is calculated through post-data analysis and processing. At the same time, the sweep wave detects the loss of waves of different frequency components under different moisture content conditions, and through time domain analysis and frequency domain analysis of the sweep signal, the influence of moisture content on different excitation frequency signals is determined, and the excitation frequency suitable for moisture content monitoring is selected. In the swept frequency wave detection stage, the NI data acquisition and analysis system first transmits a sine swept frequency wave. The signal is amplified by the power amplifier and then input into the piezoelectric smart aggregate sensor located on one side of the specimen. Due to the inverse piezoelectric effect, the electrical signal is converted into a stress wave vibration signal and propagates in the slope specimen in the form of a wave. The piezoelectric smart aggregate sensor located on the other side of the specimen receives the stress wave signal and converts it into an electrical signal and transmits it back to the NI data acquisition and analysis system.

[0025] Step (VI) Data analysis and processing: Under different water content conditions, the average amplitude value of the received stress wave signal is analyzed to obtain the variation trend of the stress wave amplitude with the water content; at the same time, the energy index based on the wavelet packet is calculated based on the collected stress wave information to obtain the variation trend of the waveform energy with the water content at different frequencies; the water content in the soil slope specimen is preliminarily determined based on the relative size of the stress wave amplitude, energy index, etc.; the formula is used to calculate the water content of the soil slope specimen.

[0026] MCI i =d·ω·s·(I i -I 0 ) / I 0 100%

[0027] Calculate the moisture index, where MIi is the moisture index, Ii is the amplitude and energy index of the received stress wave signal under the i-th working condition, I0 is the amplitude and energy index of the received stress wave under the initial state, ω is the frequency influence coefficient of the excitation signal, d is the influence coefficient of the distance between sensors on the stress wave signal, and s is the influence coefficient of the soil parameter. The monitoring system with different excitation sweep waves, different sensor spacings, and different types of soil is calibrated to determine the values ​​of parameters ω, d, and s, and the moisture index of the soil slope under different moisture content conditions can be obtained.

[0028] Preferably, in step (V), the optimal excitation frequency range of the sinusoidal sweep is 100 to 150 kHz, the sweep signal amplitude is 3 V, and the period is 1 s.

[0029] (III) Beneficial effects

[0030] The present invention provides a system for monitoring the moisture content of slope soil based on piezoelectric intelligent aggregate. It has the following beneficial effects:

[0031] The system for monitoring the moisture content of slope soil based on piezoelectric smart aggregate is a new nondestructive test (NDT) method. It uses a piezoelectric smart aggregate sensor array (Smart aggregate transducer) to set up inside the soil slope and integrate related functional devices to form a set of easy-to-use, economical and efficient moisture content data acquisition, analysis and processing system. In combination with Labview, Matlab and other related processing software, it can monitor the moisture content of the soil slope in real time online for a long time, realize the long-term, online, remote and rapid monitoring of the moisture content inside the soil slope, and can accurately evaluate the moisture content of each key position inside the soil slope. The response speed is fast and the whole system has good stability and durability. The test results show that the sensor and integrated system have good adaptability, stability and high measurement accuracy, and can be widely used in various soil slope engineering structures. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a schematic diagram of a specific device of the soil moisture content monitoring method of the present invention;

[0033] Figure 2 This is a schematic diagram of the internal structure of the piezoelectric ceramic sheet implanted smart aggregate of the present invention;

[0034] Figure 3 This is a time domain signal diagram of the piezoelectric intelligent aggregate receiving stress waves when the moisture content is 20% according to the present invention;

[0035] Figure 4 This is a time domain signal diagram of the piezoelectric intelligent aggregate receiving stress waves when the moisture content is 40% according to the present invention;

[0036] Figure 5 This is a time domain signal diagram of the piezoelectric intelligent aggregate receiving stress waves when the moisture content is 60%;

[0037] Figure 6 This is a time domain signal diagram of the piezoelectric intelligent aggregate receiving stress waves when the moisture content is 80% according to the present invention;

[0038] Figure 7 This is a time domain signal diagram of the piezoelectric intelligent aggregate receiving stress waves when the moisture content is 100%;

[0039] Figure 8 It is a relationship curve diagram of soil moisture index and soil moisture content of the present invention.

[0040] In the figure: 1. Computer; 2. NI data acquisition and analysis system; 3. Power amplifier; 4. Piezoelectric intelligent aggregate sensor; 5. Sliding slope; 6. Sliding bed; 7. Slope body; 8. Piezoelectric ceramic sheet; 9. Electrical conductor. DETAILED DESCRIPTION

[0041] 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.

[0042] like Figure 1-8 As shown, the present invention provides a technical solution: a system for monitoring the moisture content of slope soil based on piezoelectric intelligent aggregate, including a computer 1, a NI data acquisition and analysis system 2, a power amplifier 3, a piezoelectric intelligent aggregate sensor 4, a sliding slope 5, a slide bed 6, a slope body 7, a piezoelectric ceramic sheet 8 and an electric conductor 9.

[0043] The NI data acquisition and analysis system 2 is externally connected to the computer 1, and the NI data acquisition and analysis system 2 is electrically connected to the power amplifier (4).

[0044] A slope body 7 is arranged on the sliding slope surface 5 on the slide bed 6. The slope body 7 has a plurality of piezoelectric intelligent aggregate sensors 4 built therein. The piezoelectric intelligent aggregate sensors 4 are electrically connected to the NI data acquisition and analysis system 2 and the power amplifier 3 respectively.

[0045] The piezoelectric intelligent aggregate sensor 4 comprises a piezoelectric ceramic sheet 8 and an electrical conductor 9 for connecting to an external electrical component.

[0046] A system for monitoring the moisture content of slope soil based on piezoelectric intelligent aggregates, wherein the method for monitoring the moisture content comprises the following steps: Step (1) burying the piezoelectric intelligent aggregate sensor 4 into the deep part of the slope body 7 at a position where the moisture content of the soil needs to be monitored, and the directionality and position accuracy of the piezoelectric intelligent aggregate sensor 4 need to be maintained during the burial.

[0047] Step (2) Connect the relevant equipment in the monitoring system, turn on the power supply and turn on the instrument switch, and stimulate the piezoelectric intelligent aggregate sensor 4 with a high-frequency excitation signal through the NI data acquisition and analysis system 2. The frequency of the sweep signal is 100-150KHz, the amplitude is 3V, and the period is 1s;

[0048] In step (2), a high-frequency and high-voltage signal amplifier is used to amplify the excitation signal. In step (2), the high-frequency signal excited to the piezoelectric intelligent aggregate sensor 4 is a sine frequency sweep wave through the NI data acquisition and analysis system 2 .

[0049] Step (3) According to the inverse piezoelectric effect of the piezoelectric smart material, the piezoelectric smart aggregate sensor 4 converts the electrical signal into a stress wave signal. After the piezoelectric smart aggregate sensors 4 installed at different positions in the slope body 7 receive the stress wave signal, according to the positive piezoelectric effect of the piezoelectric smart material, the signal is converted into an electrical signal again and collected and stored by the NI data acquisition and analysis system 2;

[0050] Before performing step (4), the received stress wave signal is first filtered and subjected to noise reduction processing.

[0051] In step (4), the amplitude, energy, mode, wave velocity, propagation path and propagation time of the stress wave signal received by the piezoelectric intelligent aggregate sensor 4 and propagated inside the slope body 7 are compared with the system test calibration to determine the moisture content at different locations inside the soil slope.

[0052] Step (4) establishes a functional relationship between the stress wave signal received by the piezoelectric intelligent aggregate sensor 4 and the moisture content of the slope soil based on the amplitude, energy, mode, wave velocity, propagation path and propagation time of the stress wave signal propagated inside the slope body 7, and then determines the moisture content at different positions of the slope body 7.

[0053] System test calibration includes the following steps:

[0054] Step (I): Collect representative soil samples from the soil slope to be monitored and place them in a drying oven to fully dry until they are completely dry and the mass of the soil sample no longer decreases;

[0055] Step (II): Take out the soil sample and weigh it to obtain the mass of the soil sample in a completely dry state as m1. At this time, the moisture content of the soil is 0%;

[0056] Step (III): Stir and mix the completely dried soil sample with the same mass of water, and use a mold to make a soil slope specimen. At this time, the initial moisture content of the slope specimen is 100%. Before making the slope specimen, a piezoelectric intelligent aggregate sensor 4 is pre-buried at a specific position inside the soil slope specimen. The two sensors are separated by a certain distance, which is consistent with the sensor spacing in the soil slope to be monitored. To ensure the stability and reliability of the test results, the number of specimens is three groups;

[0057] Step (IV): using the monitoring system of the present invention and the wave method in the active sensing method, stress wave signal detection is performed on three groups of soil slope specimens to obtain waveform information of received stress waves when the initial water content is 100%;

[0058] Step (V) Calibration of relative moisture content: Place the soil slope specimen on a digital balance and place it in a 40°C constant temperature box to dry it and lose water. The evaporation amount of moisture in the soil slope specimen is obtained according to the reading of the balance, weighed and recorded as mi, and then the moisture content of the specimen is calculated. Stress wave signal detection is performed at this moisture content to obtain stress wave information under different relative moisture content conditions; for each working condition, a single pulse wave with a sinusoidal sweep frequency of 100 to 150KHz is used for testing; the sweep wave is used to compare the differences in the received stress wave signals under different moisture content conditions, and the relevant moisture content evaluation index is calculated through post-data analysis and processing. At the same time, the sweep wave detects the loss of waves of different frequency components under different moisture content conditions, and through time domain analysis and frequency domain analysis of the sweep signal, the influence of moisture content on different excitation frequency signals is determined, and the excitation frequency suitable for moisture content monitoring is selected. In the sweep wave detection stage, the NI data acquisition and analysis system first emits a sine sweep wave, which is amplified by the power amplifier 3 and then input into the piezoelectric smart aggregate sensor 4 located on one side of the specimen. Due to the inverse piezoelectric effect, the electrical signal is converted into a stress wave vibration signal and propagates in the slope specimen in the form of a wave. The piezoelectric smart aggregate sensor 4 located on the other side of the specimen receives the stress wave signal and converts it into an electrical signal, which is then transmitted back to the NI data acquisition and analysis system 2.

[0059] In step (V), the optimal excitation frequency range of the sinusoidal sweep is 100 to 150 kHz, the sweep signal amplitude is 3 V, and the period is 1 s.

[0060] Step (VI) Data analysis and processing: Under different water content conditions, the average amplitude value of the received stress wave signal is analyzed to obtain the variation trend of the stress wave amplitude with the water content; at the same time, the energy index based on the wavelet packet is calculated based on the collected stress wave information to obtain the variation trend of the waveform energy with the water content at different frequencies; the water content in the soil slope specimen is preliminarily determined based on the relative size of the stress wave amplitude, energy index, etc.; the formula is used to calculate the water content of the soil slope specimen.

[0061] MCI i =d·ω·s·(I i -I 0 ) / I 0 100%

[0062] Calculate the moisture index, where MIi is the moisture index, Ii is the amplitude and energy index of the received stress wave signal under the i-th working condition, I0 is the amplitude and energy index of the received stress wave under the initial state, ω is the frequency influence coefficient of the excitation signal, d is the influence coefficient of the distance between sensors on the stress wave signal, and s is the influence coefficient of the soil parameter. The monitoring system with different excitation sweep waves, different sensor spacings, and different types of soil is calibrated to determine the values ​​of parameters ω, d, and s, and the moisture index of the soil slope under different moisture content conditions can be obtained.

[0063] When using, step 1: calibrate the system before use according to different excitation frequencies, sensor spacings and soil slopes of different soil types; after the calibration, the corresponding relationship between the moisture index and the moisture content of the soil slope under the conditions of this type of soil slope and this excitation frequency and sensor spacing can be obtained.

[0064] Step 2: bury the piezoelectric intelligent aggregate sensor 4 in the deep part of the slope body 7 (soil slope) where the soil moisture content needs to be monitored. During the burial, the directionality and position accuracy of the piezoelectric intelligent aggregate sensor 4 must be maintained.

[0065] Step 3: Connect the relevant equipment in the monitoring system, turn on the power and turn on the instrument switch, and send a high-frequency excitation signal to the piezoelectric intelligent aggregate sensor 4 through the NI data acquisition and analysis system 2. The sweep signal frequency is 100-150KHz, the amplitude is 3V, and the period is 1s;

[0066] The entire stress wave data collection process is very short, only 1 second, so the volatilization of water inside the soil slope during this process can be completely ignored. It is assumed that the water content inside the slope remains unchanged during each data collection process.

[0067] Step 4: Based on the inverse piezoelectric effect of the piezoelectric smart material, the piezoelectric smart aggregate sensor 4 converts the electrical signal into a stress wave signal. After receiving the stress wave signal, the piezoelectric smart aggregate sensor 4 installed at different positions in the slope body 7 converts the signal into an electrical signal again based on the positive piezoelectric effect of the piezoelectric smart material and collects and stores it by the oscilloscope;

[0068] Step 5: Determine the moisture content at different positions of the slope body according to the amplitude, energy, mode, wave velocity, propagation path and propagation time of the stress wave signal received by the piezoelectric intelligent aggregate sensor 4 propagating inside the slope body 7. Calculate the moisture index of the soil slope between the sensors by formula (1).

[0069] Step 6: According to the system calibration results, the moisture content index of the soil slope is obtained by detecting the stress wave waveform information to determine the moisture content information of the monitored soil slope.

[0070] In summary, the system for monitoring the moisture content of slope soil based on piezoelectric smart aggregate sets a piezoelectric smart aggregate sensor array (Smart aggregate transducer) inside the soil slope and integrates relevant functional devices to form a set of easy-to-use, economical and efficient moisture content data acquisition, analysis and processing system. In combination with Labview, Matlab and other related processing software, the system can conduct long-term real-time online monitoring of the moisture content of the soil slope, realize long-term, online, remote and rapid monitoring of the moisture content inside the soil slope, accurately evaluate the moisture content of each key position inside the soil slope, respond quickly and the whole system has good stability and durability.

[0071] It should be noted that the electrical components appearing in this article are all connected to the external main controller and 220V mains electricity, and the main controller can be a conventional known device for controlling computers, etc. Its control principle, internal structure and control switch mode are all conventional means of the prior art, which are directly quoted here without further elaboration. In this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0072] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A system for monitoring the moisture content of slope soil based on piezoelectric intelligent aggregate, characterized in that: It includes a computer (1), a NI data acquisition and analysis system (2), a power amplifier (3), a piezoelectric intelligent aggregate sensor (4), a sliding slope (5), a sliding bed (6), a slope body (7), a piezoelectric ceramic sheet (8), and an electric conductor (9); The NI data acquisition and analysis system (2) is externally connected to the computer (1), and the NI data acquisition and analysis system (2) is electrically connected to the power amplifier (3); A slope body (7) is arranged on the sliding slope surface (5) on the slide bed (6), and a plurality of piezoelectric intelligent aggregate sensors (4) are built into the slope body (7), and the piezoelectric intelligent aggregate sensors (4) are electrically connected to the NI data acquisition and analysis system (2) and the power amplifier (3) respectively; The piezoelectric intelligent aggregate sensor (4) comprises a piezoelectric ceramic sheet (8) and an electrical conductor (9) for connecting to an external electrical component; When using, step 1: calibrate the system before use according to different excitation frequencies, sensor spacings and soil slopes of different soil types; after the calibration, the corresponding relationship between the moisture index and moisture content of the soil slope under the conditions of this type of soil slope, this excitation frequency and sensor spacing can be obtained; Step 2: bury the piezoelectric intelligent aggregate sensor (4) in the deep part of the slope body (7) where the soil moisture content needs to be monitored. When burying the piezoelectric intelligent aggregate sensor (4), the directionality and position accuracy of the piezoelectric intelligent aggregate sensor (4) must be maintained; Step 3: Connect the relevant equipment in the monitoring system, turn on the power supply and turn on the instrument switch, and send a high-frequency excitation signal to the piezoelectric intelligent aggregate sensor (4) through the NI data acquisition and analysis system (2). The sweep signal frequency is 100~150KHz, the amplitude is 3V, and the period is 1s; The entire stress wave data collection process is very short, only 1 second, so the volatilization of water inside the soil slope during this process can be completely ignored. It is assumed that the water content inside the slope remains unchanged during each data collection process. Step 4: Based on the inverse piezoelectric effect of the piezoelectric smart material, the piezoelectric smart aggregate sensor (4) converts the electrical signal into a stress wave signal. After receiving the stress wave signal, the piezoelectric smart aggregate sensors (4) installed at different positions in the slope body (7) convert the signal into an electrical signal again based on the direct piezoelectric effect of the piezoelectric smart material and collect and store it on the oscilloscope; Step 5: Determine the moisture content at different positions of the slope body (7) based on the amplitude, energy, mode, wave velocity, propagation path and propagation time of the stress wave signal received by the piezoelectric intelligent aggregate sensor (4) and propagated inside the slope body (7); calculate the moisture content index of the soil slope between the sensors by formula (1); Step 6: According to the system calibration results, the moisture content index of the soil slope is obtained by detecting the stress wave waveform information to determine the moisture content information of the monitored soil slope.

2. According to the system for monitoring the moisture content of slope soil based on piezoelectric intelligent aggregate according to claim 1, the method for monitoring the moisture content comprises the following steps: Step (1) burying the piezoelectric intelligent aggregate sensor (4) in the deep part of the slope body (7) at a position where the moisture content of the soil needs to be monitored, and maintaining the directionality and position accuracy of the piezoelectric intelligent aggregate sensor (4) during burying; Step (2) Connect the relevant equipment in the monitoring system, turn on the power supply and turn on the instrument switch, and stimulate the piezoelectric intelligent aggregate sensor (4) with a high-frequency excitation signal through the NI data acquisition and analysis system (2), the sweep signal frequency is 100~150KHz, the amplitude is 3V, and the period is 1s; Step (3) Based on the inverse piezoelectric effect of the piezoelectric smart material, the piezoelectric smart aggregate sensor (4) converts the electrical signal into a stress wave signal. After receiving the stress wave signal, the piezoelectric smart aggregate sensor (4) installed at different positions in the slope body (7) converts the signal into an electrical signal again based on the positive piezoelectric effect of the piezoelectric smart material, and the signal is collected and stored by the NI data acquisition and analysis system (2); Step (4) establishes a functional relationship between the amplitude, energy, mode, wave velocity, propagation path and propagation time of the stress wave signal received by the piezoelectric intelligent aggregate sensor (4) and the moisture content of the slope soil, thereby determining the moisture content at different positions of the slope body (7).

3. The method for monitoring the moisture content of slope soil based on piezoelectric intelligent aggregate according to claim 2 is characterized by: In the step (2), a high-frequency and high-voltage signal amplifier is used to amplify the excitation signal.

4. The method for monitoring the moisture content of slope soil based on piezoelectric intelligent aggregate according to claim 2 is characterized by: Before performing step (4), the received stress wave signal is first filtered and subjected to noise reduction processing.

5. The method for monitoring the moisture content of slope soil based on piezoelectric intelligent aggregate according to claim 2 is characterized by: In the step (2), the high-frequency signal excited by the piezoelectric intelligent aggregate sensor (4) through the NI data acquisition and analysis system (2) is a sine frequency sweep wave.

6. The method for monitoring the moisture content of slope soil based on piezoelectric intelligent aggregate according to claim 2 is characterized by: In the step (4), the amplitude, energy, mode, wave velocity, propagation path and propagation time of the stress wave signal received by the piezoelectric intelligent aggregate sensor (4) propagating inside the slope body (7) are compared with the system test calibration to determine the moisture content at different positions inside the soil slope.

7. The method for monitoring the moisture content of slope soil based on piezoelectric intelligent aggregate according to claim 5 is characterized by: System test calibration includes the following steps: Step (I): Collect representative soil samples from the soil slope to be monitored and place them in a drying oven to fully dry until they are completely dry and the mass of the soil sample no longer decreases; Step (II): Take out the soil sample and weigh it to get the mass of the soil sample in a completely dry state as m1. At this time, the moisture content of the soil is 0%; Step (III): fully mixing the completely dried soil sample with water of the same mass, and using a mold to make a soil slope specimen, wherein the initial moisture content of the slope specimen is 100%; before making the slope specimen, pre-burying a piezoelectric intelligent aggregate sensor (4) at a specific position inside the soil slope specimen, with a certain distance between the two sensors, which is consistent with the distance between the sensors in the soil slope to be monitored; to ensure the stability and reliability of the test results, the number of specimens is three groups; Step (IV): Using the monitoring system and the wave method in the active sensing method, the stress wave signal of the three groups of soil slope specimens is detected to obtain the waveform information of the received stress wave when the initial water content is 100%; Step (V) Calibration of relative moisture content: Place the soil slope specimen on a digital balance and place it in a 40°C constant temperature box to dry it out; obtain the evaporation of moisture from the soil slope specimen based on the reading of the balance, weigh it and record it as mi, and then calculate the moisture content of the specimen; and perform stress wave signal detection at this moisture content to obtain stress wave information under different relative moisture content conditions; for each working condition, a single pulse wave with a sinusoidal sweep frequency of 100~150KHz is used for testing; the sweep wave is used to compare the differences in the received stress wave signals under different moisture content conditions, and calculate the relevant moisture content evaluation index through subsequent data analysis and processing; at the same time, the sweep wave detects waves of different frequency components in The loss under different moisture content conditions is determined by analyzing the time domain and frequency domain of the swept frequency signal to determine the influence of the moisture content on the different excitation frequency signals, and the excitation frequency suitable for moisture content monitoring is selected; in the swept frequency wave detection stage, the NI data acquisition and analysis system (2) first transmits a sinusoidal swept frequency wave, and the signal is amplified by the power amplifier (3) and then input into the piezoelectric smart aggregate sensor (4) located on one side of the specimen. Due to the inverse piezoelectric effect, the electrical signal is converted into a stress wave vibration signal, and propagates in the slope specimen in the form of a wave. After receiving the stress wave signal, the piezoelectric smart aggregate sensor (4) located on the other side of the specimen converts it into an electrical signal and transmits it back to the NI data acquisition and analysis system (2); Step (VI) Data analysis and processing: Under different water content conditions, the average amplitude of the received stress wave signal is analyzed to obtain the variation trend of the stress wave amplitude with the water content; at the same time, the energy index based on the wavelet packet is calculated based on the collected stress wave information to obtain the variation trend of the waveform energy with the water content at different frequencies; the water content in the soil slope specimen is preliminarily determined based on the relative size of the stress wave amplitude and the energy index; the formula is used to , Calculate the moisture index, where MIi is the moisture index, Ii is the amplitude and energy index of the received stress wave signal under the i-th working condition, I0 is the amplitude and energy index of the received stress wave under the initial state, ω is the frequency influence coefficient of the excitation signal, d is the influence coefficient of the distance between sensors on the stress wave signal, and s is the influence coefficient of the soil parameter; calibrate the monitoring system with different excitation sweep waves, different sensor spacings, and different types of soil, determine the values ​​of parameters ω, d, and s, and obtain the moisture index of the soil slope under different moisture content conditions.

8. The method for monitoring the moisture content of slope soil based on piezoelectric intelligent aggregate according to claim 7 is characterized by: In step (V), the optimal excitation frequency range of the sine sweep is 100-150 kHz, the sweep signal amplitude is 3 V, and the period is 1 s.

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