Single column soil moisture test method

Abstract

The application discloses a single-column soil moisture content testing method and belongs to the technical field of soil moisture content testing, and solves the problem that the existing soil moisture content testing method cannot accurately prevent geological disasters. The application obtains the measurement data containing the measurement impedance module and the measurement phase in the monitoring soil layer by using a plurality of measurement electrodes in the soil testing column, and obtains the comprehensive correlation coefficient by calculating the impedance module correlation coefficient and the phase correlation coefficient between the measurement and calibration data. The calibration soil moisture content distribution soil layer closest to the monitoring soil layer is determined by combining the impedance module and the phase, the calibration experimental soil layer has stronger robustness, even when the environmental conditions change, the strategy can be quickly adjusted by comparing the calibration data, the continuity and stability of the monitoring work are ensured, and experts can accurately evaluate the geological disaster warning level.

Description

Technical Field

[0001] The present invention relates to the technical field of soil moisture testing, and in particular to a single-column soil moisture testing method. Background Art

[0002] Soil moisture is closely related to geological hazards. High moisture content reduces soil shear strength and increases soil weight, thereby increasing the risk of landslides and debris flows. Furthermore, changes in soil moisture can lead to ground subsidence and soil collapse, particularly in soft soil areas and geological structures with cavities. Therefore, accurate monitoring of soil moisture is crucial for early warning and prevention of geological hazards.

[0003] Currently, most existing technologies assess the risk of geological disasters by directly measuring soil moisture content. For example, patent application CN111537567B discloses a needle-type soil moisture detection method, which includes a detector body and a probe rod. The probe rod is connected to the lower end of the detector body, and a control panel is provided on the upper surface of the detector body. The lower end of the probe rod is designed to be sharp. The outer wall of the lower end of the probe rod is embedded with a high-frequency electrode sheet distributed in a ring shape. The surface of the high-frequency electrode sheet is in contact with the outer wall of the lower end of the probe rod. The lower end of the probe rod is embedded in the outer wall of the probe rod. A detection port is embedded in the outer wall of the probe rod. A protective net and a permeable membrane are embedded in the detection port. The lower end of the probe rod is provided with symmetrically distributed high-frequency electrode contacts. The detector body includes a power module, a high-frequency voltage generator, a voltage meter, and a microprocessor. This invention uses the high-frequency electrode sheet to ionize the water in the soil and detects the conductivity between the high-frequency electrode contacts to quickly and effectively measure the moisture content. However, directly measuring the conductivity cannot accurately reflect the soil moisture content information, and thus cannot accurately provide early warning of geological disasters. Summary of the Invention

[0004] In response to the above-mentioned problems in the prior art, the present invention provides a single-column soil moisture testing method, which solves the problem that the existing soil moisture detection method cannot accurately prevent geological disasters.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0006] A single-column soil moisture testing method is provided, comprising the steps of:

[0007] S1. Install the soil test column in the monitoring soil layer; wherein, the soil test column is provided with Each soil electrode is electrically connected to the four measurement interfaces in the measurement circuit through four multi-way switches. is a natural number greater than or equal to 4;

[0008] S2. Place the soil in the test column. The soil electrodes are sorted and numbered respectively, and grouped into groups of 4 adjacent soil electrodes. Soil electrodes are divided into a set of measuring electrodes;

[0009] S3. The measurement data of all measuring electrodes in the monitored soil layer at different characteristic frequencies are obtained through the measurement circuit. The measurement data include and ;in, For the The measuring electrodes are The measured impedance modulus obtained at the characteristic frequency is For the The measuring electrodes are The measured phase obtained at the characteristic frequency;

[0010] S4. Calculate the correlation coefficient between the measured data and the calibration data;

[0011] The calibration data includes and , For the The first soil layer in the calibrated soil moisture distribution The measuring electrodes are The calibrated impedance modulus obtained by the characteristic frequency; For the The first soil layer in the calibrated soil moisture distribution The measuring electrodes are The calibration phase obtained at the characteristic frequency; the correlation coefficient includes 、 and , For the Calibrated soil moisture distribution in soil layers and Impedance modulus correlation coefficient between ; For the Calibrated soil moisture distribution in soil layers and The phase correlation coefficient between For the The comprehensive correlation coefficient between the calibrated soil moisture distribution soil layer and the measured data is obtained through and Calculated;

[0012] S5. Acquisition The maximum value in , will be with The corresponding calibrated soil moisture distribution soil layer is used as the actual soil moisture distribution soil layer of the monitoring soil layer;

[0013] S6. Based on the actual soil moisture content, soil layer distribution and geological structure of the monitored soil layer, the geological disaster warning level of the monitored soil layer is given by expert evaluation.

[0014] In this scheme, multiple sets of measuring electrodes in a soil test column acquire measurement data from the monitoring soil layer, including the measured impedance modulus and phase. By calculating the impedance modulus correlation coefficient and phase correlation coefficient between the measured and calibrated data and obtaining a comprehensive correlation coefficient, the impedance modulus and phase are combined to simultaneously determine the calibration soil moisture distribution layer that most closely matches the monitoring soil layer. The calibration soil moisture distribution layer serves as the baseline value for the calibration experiment. Considering the complex and variable conditions of the actual monitoring soil layer, the calibration experiment soil layer provides enhanced robustness. Even when environmental conditions change, the strategy can be quickly adjusted by comparing the calibration data, ensuring the continuity and stability of the monitoring operation and facilitating expert assessment of accurate geological hazard warning levels. The impedance modulus refers to the absolute value of the complex impedance, representing the overall resistance encountered by current passing through the medium. When the moisture content in the soil increases, the impedance modulus decreases due to water's higher dielectric constant. The phase refers to the phase difference between the voltage and current, reflecting the capacitive and inductive components of the medium. Changes in moisture content not only alter the soil's resistivity but also its capacitive properties, which in turn alters the phase. As the moisture content increases, the capacitance effect of the soil increases, causing the phase to increase. The combination of impedance mode and phase can better reflect the moisture content of the soil than conductivity alone.

[0015] Furthermore, each soil test column includes a cylindrical shell, the bottom of the shell is a conical structure, a top cover is provided on the top of the shell, a filling layer is provided inside the shell, an electrode sandwich is provided between the inner wall of the shell and the outer wall of the filling layer, and an electrode is fixed on the electrode sandwich. Soil electrodes, One end of each soil electrode passes through multiple measuring holes on the shell and contacts the soil. The other end of each soil electrode is electrically connected to the measurement circuit located on the fill layer via an electrode connection wire. The soil test column is easy to install and maintain, ensuring the stability and repeatability of the measurement results.

[0016] Furthermore, the inner wall of the housing is provided with multiple guide grooves along its height, and the outer wall of the filling layer is provided with flanges that slidably engage with the guide grooves. The design of the guide grooves and flanges allows the filling layer to slide up and down within the housing without rotating, ensuring the consistency of the soil electrode position, improving measurement accuracy, reducing errors caused by device movement, and enhancing the reliability of test results.

[0017] Furthermore, the outer wall of the conical structure at the bottom of the housing is provided with multiple fixing holes for the locking clips to pass through. Multiple guide holes are vertically arranged inside the filling layer. The bottoms of the guide holes are curved and connected to the fixing holes. The tips of the multiple locking clips enter the guide holes and drill out from them into the soil. The design of the fixing holes on the outer wall of the conical structure, the internal guide holes, and the locking clips ensures that the entire device can be firmly embedded in the soil, maintaining stability even in soft or slippery surface conditions. For long-term monitoring, the locking clips can prevent data deviation caused by device displacement.

[0018] Furthermore, the multiple measurement holes on the housing are evenly arranged in multiple layers along the height direction, with the holes on each layer arranged in a circular pattern. This uniform, layered, and circular distribution of the holes ensures consistent soil contact area between each electrode, thereby improving the comparability of soil moisture measurements at different depths. This layout also facilitates effective contact between the electrodes and the soil, further enhancing measurement accuracy.

[0019] Furthermore, a fixing plate for fixing the measuring circuit with bolts is provided on the top of the filling layer, and a connecting wire through-hole for passing a plurality of electrode connecting wires is provided in the middle of the fixing plate.

[0020] Furthermore, the measurement circuit includes four measurement interfaces: a first measurement interface, a second measurement interface, a third measurement interface, and a fourth measurement interface, which are electrically connected to four multi-way switches. The first measurement interface is electrically connected to a resistor, a sinusoidal signal generator, and the fourth measurement interface in sequence. The resistor is connected in parallel with a resistor voltage amplifier electrically connected to a resistor voltage analog-to-digital converter, which is electrically connected to a microprocessor. The sinusoidal signal generator is electrically connected to the microprocessor. The second and third measurement interfaces are both electrically connected to a soil voltage amplifier, which is electrically connected to the microprocessor via a soil voltage analog-to-digital converter. The microprocessor is signal-connected to a remote monitoring terminal via a communication interface. The measurement circuit can simultaneously obtain resistor voltage and soil voltage information, providing a basis for calculating the impedance modulus. The use of the microprocessor and remote monitoring terminal enables automated data processing and real-time transmission, greatly improving work efficiency.

[0021] Furthermore, and The calculation method includes the following steps:

[0022] S3.1, set the frequency of the sine signal generator to the first The sampling frequencies of the soil voltage analog-to-digital converter and the resistance voltage analog-to-digital converter are set to characteristic frequencies times;;

[0023] S3.2, respectively obtain The output data of 100 soil voltage analog-to-digital converters and resistance voltage analog-to-digital converters are connected to the measuring electrodes. and , and calculate 100 and The absolute deviation value, and 100 and Deviation value of

[0024] S3.3 Calculation and ;

[0025]

[0026]

[0027] in, For 100 The sum of the absolute deviations of For 100 The sum of the absolute deviations of For 100 The sequence number of the negative zero crossing point in the deviation value; For 100 The sequence number of the negative zero crossing point in the deviation value.

[0028] This solution sets the output frequency of the sinusoidal signal generator and the sampling frequency of the analog-to-digital converter, then calculates the impedance modulus based on the absolute deviation of a large number of sample points. This increases the amount of data collected, reduces the impact of random errors, and improves the accuracy of the impedance modulus calculation. This solution uses the sequence number of negative zero-crossing points to determine the phase. By analyzing a large number of sample points, a more accurate phase can be obtained and it is easier to distinguish different types of soil media.

[0029] Furthermore, the characteristic frequencies include impedance mode characteristic frequencies and phase characteristic frequencies corresponding to a plurality of calibrated soil moisture distribution layers. The method for obtaining the impedance mode characteristic frequency and phase characteristic frequency in each calibrated soil moisture distribution layer is:

[0030] The soil test column is installed in the soil layer corresponding to the soil moisture distribution, and the impedance mode mean square error and phase mean square error of all combinations of measuring electrodes at different frequencies are obtained. The frequency corresponding to the maximum value of all impedance mode mean square errors is taken as the impedance mode characteristic frequency of the soil layer corresponding to the soil moisture distribution, and the frequency corresponding to the maximum value of all phase mean square errors is taken as the impedance mode characteristic frequency of the soil layer corresponding to the soil moisture distribution.

[0031] In this solution, by measuring the impedance modulus mean square error and phase mean square error of all combinations of measuring electrodes at different frequencies and selecting the frequency corresponding to the maximum mean square error as the characteristic frequency, the optimal operating frequency that reflects changes in soil moisture can be more accurately determined. This helps improve the accuracy and reliability of subsequent soil moisture monitoring. At the same time, determining the optimal impedance modulus characteristic frequency and phase characteristic frequency can help adjust the frequency of the sinusoidal signal generator in the measurement circuit, allowing the equipment to operate within the most sensitive frequency range, thereby obtaining more accurate data. Based on this, changes in soil moisture can be detected earlier and more accurately, which is particularly important for early warning of geological disasters.

[0032] Furthermore, The calculation method is:

[0033] =

[0034]

[0035]

[0036]

[0037]

[0038]

[0039]

[0040] in, and Respectively The average impedance modulus and phase value of all combined measuring electrodes in a calibrated soil moisture distribution layer; is the total number of characteristic frequencies; K is the number of combinations of all measuring electrodes ; and They are and The average value of .

[0041] This scheme uses two parameters, impedance mode and phase, for comprehensive analysis, which can not only capture the changes in soil resistivity, but also reflect the influence of soil capacitance characteristics, which helps to monitor soil moisture content and its changing trends more comprehensively and reliably.

[0042] The present invention discloses a single-column soil moisture content testing method, which has the following beneficial effects:

[0043] The present invention uses multiple groups of measuring electrodes in the soil test column to obtain measurement data of the monitored soil layer including the measurement impedance mode and the measurement phase, and calculates the impedance mode correlation coefficient and the phase correlation coefficient between the measurement and calibration data to obtain a comprehensive correlation coefficient. By combining the impedance mode and the phase, the calibration soil moisture distribution layer closest to the monitored soil layer is simultaneously judged. The calibration experimental soil layer has stronger robustness. Even when the environmental conditions change, the strategy can be quickly adjusted by comparing the calibration data, thereby ensuring the continuity and stability of the monitoring work and facilitating experts to assess the accurate geological disaster warning level. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 This is a schematic diagram of the structure of the soil test column;

[0045] Figure 2 is a front view of the housing;

[0046] Figure 3 is a schematic cross-sectional view of the housing;

[0047] Figure 4 Schematic diagram of the structure of the electrode interlayer;

[0048] Figure 5 is a schematic diagram of the soil electrode;

[0049] Figure 6 is a top view of the filling layer;

[0050] Figure 7 is the internal schematic diagram of the filling layer;

[0051] Figure 8 is a top view of the fixed plate;

[0052] Figure 9 It is a schematic diagram of the connection between the electrode connector and the measuring circuit;

[0053] Figure 10 This is the connection diagram of the measurement circuit;

[0054] Figure 11 This is a schematic diagram of the composition of a multi-way switch;

[0055] Figure 12 Schematic diagram of the structure of the sine signal generator;

[0056] Figure 13 It is a structural diagram of the soil voltage amplifier and the resistance voltage amplifier;

[0057] Figure 14 It is a schematic diagram of the structure of the microprocessor;

[0058] Among them: 1. Shell; 2. Electrode interlayer; 22. Soil electrode; 23. Electrode connecting wire; 24. Conductor; 30. Filling layer; 40. Fixing plate; 41. Connecting wire perforation; 5. Top cover; 6. Circuit board; 101. Electrode connector; 102. Connecting cable; 103. Multi-way switch; 104. Measuring circuit; 105. Data acquisition server; 116-1. First measurement interface; 116-2. Second measurement interface; 116-3. Third measurement interface; 116-4. Fourth measurement interface; 117. Soil voltage amplifier; 118. Resistor; 119. Sine signal generator; 120. Resistor voltage amplifier; 121. Soil voltage analog-to-digital converter; 122. Resistor voltage analog-to-digital converter; 123. Microprocessor; 124. Communication interface. DETAILED DESCRIPTION

[0059] The specific embodiments of the present invention are described below to facilitate understanding of the present invention by those skilled in the art. However, it should be clear that the present invention is not limited to the scope of the specific embodiments. For those skilled in the art, as long as various changes are within the spirit and scope of the present invention as defined and determined by the appended claims, these changes are obvious, and all inventions and creations utilizing the concepts of the present invention are protected.

[0060] refer to Figure 1 This embodiment provides a single-column soil moisture testing method, the purpose of which is to solve the problem that existing soil moisture detection methods cannot prevent geological disasters. It is demonstrated in detail below.

[0061] A single-column soil moisture testing method comprises the following steps:

[0062] S1. Install the soil test column in the monitoring soil layer. Figure 1 and Figure 9 , where each soil test column is equipped with Each soil electrode 22 is electrically connected to four measurement interfaces in the measurement circuit 104 through four multi-way switches 103. is a natural number greater than or equal to 4.

[0063] S2. Place the soil in the test column. The soil electrodes 22 are sorted and numbered, and grouped into groups of four adjacent soil electrodes 22. Soil electrodes 22 divided into Set of measuring electrodes.

[0064] S3, the measurement data of all the measurement electrodes in the monitored soil layer at different characteristic frequencies are obtained through the measurement circuit 104. The measurement data include and ;in, For the The measuring electrodes are The measured impedance modulus obtained at the characteristic frequency is For the The measuring electrodes are The measured phase is obtained at the characteristic frequency.

[0065] S4. Calculate the correlation coefficient between the measured data and the calibration data.

[0066] The calibration data includes and , For the The first soil layer in the calibrated soil moisture distribution The measuring electrodes are The calibrated impedance modulus obtained by the characteristic frequency; For the The first soil layer in the calibrated soil moisture distribution The measuring electrodes are The calibration phase obtained at the characteristic frequency; the correlation coefficient includes 、 and , For the Calibrated soil moisture distribution in soil layers and Impedance modulus correlation coefficient between ; For the Calibrated soil moisture distribution in soil layers and The phase correlation coefficient between For the The comprehensive correlation coefficient between the calibrated soil moisture distribution soil layer and the measured data is obtained through and Obtained by calculation.

[0067] S5. Acquisition The maximum value in , will be with The corresponding calibrated soil moisture distribution soil layer is used as the actual soil moisture distribution soil layer of the monitoring soil layer.

[0068] S6. Based on the actual soil moisture content, soil layer distribution and geological structure of the monitored soil layer, the geological disaster warning level of the monitored soil layer is given by expert evaluation.

[0069] As a further solution of this embodiment, it is possible to judge in sequence Is the impedance modulus difference and phase difference of the group greater than the corresponding threshold value set for the calibration soil moisture distribution layer? If the impedance modulus difference and phase difference of the group of measuring electrodes are greater than the corresponding thresholds, the monitoring soil layer is located Soil electrode No. 22 and There is an abnormality in the soil moisture content between soil electrodes 22. is greater than or equal to 1 and less than or equal to Otherwise, the monitored soil layer is normal.

[0070] This embodiment If any one of the impedance modulus difference and phase difference of the group of measuring electrodes is greater than the corresponding threshold value set, it means that the soil moisture content in the monitored soil layer is abnormal and there is a possibility of a geological disaster. The inventors consider that, ideally, the simultaneous changes of the impedance modulus and phase should be considered. If both show a clear deviation trend, it is more likely to indicate that the soil moisture content has indeed changed. However, in practical applications, sometimes only one parameter may show a significant change. For example, if a large amount of free water suddenly appears in the soil, the first thing to be affected may be the impedance modulus because it is more sensitive to changes in resistivity; the change in phase will be delayed, or become less obvious under certain conditions. Vice versa, for some specific types of soil or materials, the phase may respond more sensitively to changes in moisture content than the impedance modulus.

[0071] Specifically, refer to Figure 1 As the specific structure of the soil test column, each soil test column includes a shell 1, an electrode sandwich 2, a plurality of soil electrodes 22, a filling layer 30, a fixing plate 40 and a top cover 5.

[0072] Housing 1, reference Figure 2 . The outer shell 1 is a cylindrical structure with a hollow interior, and the bottom of the outer shell 1 is a conical structure. The outer shell 1 is made of a material with good stress resistance. In this embodiment, steel is used and it is manufactured using a casting process. A plurality of circular measuring holes are provided on the outer wall of the cylindrical structure. The multiple measuring holes on the outer shell 1 are evenly divided into multiple layers along the height direction, and the multiple measuring holes on each layer are distributed in a circular shape. The measuring holes are evenly layered and distributed in a circular shape along the height direction, which ensures the consistency of the soil contact area of ​​each electrode, thereby improving the comparability between the soil moisture measurement values ​​at different depths. Such a layout also facilitates the effective contact between the electrode and the soil, further improving the measurement accuracy.

[0073] As a further solution of this embodiment, refer to Figure 2 11-1a, 11-1b, 11-1c, 11-2a, 11-2b, 11-2c, 11-3a, 11-3b and 11-3c are all measuring holes. The multiple measuring holes are divided into three layers, with six in each layer, and the cores of the six measuring holes in the same layer are on a circle in a plane, which is perpendicular to the axis of the shell 1, and the angle between the cores of the adjacent measuring holes of the shell 1 is 60°.

[0074] A plurality of fixing holes for the lock buckle to pass through are provided on the outer wall of the conical structure at the bottom of the shell. In this embodiment, three fixing holes are distributed in a ring. The plane formed by the three fixing holes is perpendicular to the axis of the shell 1, and the angle between adjacent measuring holes is 120°. Figure 2 12-1 and 12-2 are both fixing holes.

[0075] Electrode sandwich 2, reference Figure 4 The electrode interlayer 2 is a cylindrical structure made of insulating material. In this embodiment, polytetrafluoroethylene is used. The outer diameter of the electrode interlayer 2 is smaller than the inner diameter of the upper half of the shell 1, so that the electrode interlayer 2 can be inserted into the shell 1 and fit tightly against the shell 1. The height of the electrode interlayer 2 is slightly higher than the height of the uppermost and lowermost measuring holes. At the position of the measuring hole corresponding to the shell 1, an electrode mounting hole is opened. Figure 4 21-1a, 21-1b, 21-1c, 21-2a, 21-2b, 21-2c, 21-3a, 21-3b and 21-3c are all electrode mounting holes.

[0076] The electrode mounting hole can be circular, and its radius is less than 0.8 times the radius of the measuring hole of the shell 1. Soil electrodes 22, One end of each soil electrode 22 passes through a plurality of measuring holes on the housing 1 and contacts the soil. The other end of each soil electrode 22 is electrically connected to the measurement circuit 104 located on the filling layer 30 through an electrode connecting wire.

[0077] Soil electrode 22, ref. Figure 5 The soil electrode 22 is circular and smaller than the electrode mounting hole. It is glued to the electrode mounting hole. One end of the soil electrode 22 is connected to the electrode connecting wire 23. The electrode connecting wire 23 is a connecting wire with a conductor 24 in the middle and an insulating layer on the outside. The insulating layer is peeled off at both ends, one end is welded to the inner side of the electrode, and the other end is fixed to the electrode connector 101 with a screw. The electrode connecting wire 23 is led out from the top and passes through the connecting wire through-hole 41 from the top. It is fixed to the electrode connector 101. The electrode connector 101 is electrically connected to the multi-way switch 103 via the connecting cable 102.

[0078] Filling layer 30, reference Figure 7. The filling layer 30 is made of engineering plastic and has the same shape as the interior of the outer shell 1. It is installed in the outer shell 1 and is used to fix the electrode interlayer 2 in the outer shell 1. A plurality of guide holes are vertically arranged inside the filling layer. The bottoms of the plurality of guide holes are bent and respectively connected to the plurality of fixing holes. The tips of the plurality of lock buckles respectively enter the plurality of guide holes and drill out from the plurality of fixing holes into the soil. The lock buckle is a strip-shaped cylinder with a pointed end. It is made of a material with good stress resistance and a certain deformation ability. The lock buckle is used to pass through the guide hole and embed into the soil. The design of the fixing holes on the outer wall of the conical structure and the internal guide holes and lock buckles enables the entire device to be firmly embedded in the soil and remain stable even under soft or slippery surface conditions. For long-term monitoring, the lock buckle can prevent data deviation caused by equipment displacement. Figure 7 31-1, 31-2 and 31-3 are all guide holes.

[0079] In order to facilitate the filling layer 30 to be installed in the shell 1, refer to Figure 3 and Figure 6 In this embodiment, a plurality of guide grooves are provided on the inner wall of the housing 1 along the height direction, and a flange is provided on the outer wall of the filling layer 30 to slide with the plurality of guide grooves. Figure 3 13-1, 13-2, 13-3, and 13-4 are all guide grooves. Figure 6 32-1, 32-2, 32-3, and 32-4 are all flanges. The design of the guide grooves and flanges allows the filling layer 30 to slide up and down within the housing 1 without rotating, ensuring consistent positioning of the soil electrode 22, improving measurement accuracy, and helping to reduce errors caused by device movement, thereby enhancing the reliability of test results. In this embodiment, there are three guide holes, spaced 120° apart in a circular pattern.

[0080] Fixed plate 40, reference Figure 8 The fixing plate 40 is located at the top of the filling layer and is used to fix the measuring circuit 104 with bolts. A connecting wire through-hole 41 is provided in the middle of the fixing plate 40 for multiple electrode connecting wires to pass through. The fixing plate 40 is a disc structure with an external thread on the outside, which matches the internal thread on the inside of the top of the shell 1. The fixing plate 40 is fixed to the top of the shell 1 by the external thread on the outside and the internal thread on the inside of the top of the shell 1. The fixing plate 40 has four circuit board fixing holes, which are Figure 8 42 - 1 , 42 - 2 , 42 - 3 , and 42 - 4 are all used to mount the circuit board 6 of the measuring circuit 104 .

[0081] Top cover 5, reference Figure 1 The top cover 5 matches the external thread on the top of the housing 1 and is used to be installed on the top of the housing 1 so that the internal measurement circuit 104 is in a sealed state.

[0082] This embodiment provides a method for installing a soil testing column, comprising the following steps:

[0083] Step 1: Place the electrode interlayer 2 on the filling layer 30 and install it into the housing 1; when inserting, the soil electrode 22 corresponds to the measuring hole of the housing 1 and is concentric with the soil electrode 22, and the soil electrode 22 does not touch the housing 1;

[0084] Step 2: Use a hammer to hammer the shell 1 into the monitored soil layer;

[0085] Step 3: Place the pointed ends of the three lock buckles downward and hammer them through the three guide holes and the fixing holes of the outer shell 1 into the soil layer, so that the lock buckle parts are in the soil, locking the outer shell 1; the top of the lock buckle is knocked into the inner layer.

[0086] Step 4: Pass the connecting wire through the connecting wire hole and install it to the electrode connector; and install the fixing plate 40 on the housing 1.

[0087] Step 5: Connect the electrode connector 101 to the circuit board 6;

[0088] Step 6: Mount the circuit board 6 of the measuring circuit 104 on the fixing plate 40;

[0089] Step 7: Install the top cover 5 onto the housing 1;

[0090] Complete the installation of the soil test column through the above 7 steps.

[0091] As a specific connection circuit of the measurement circuit 104 of this embodiment, refer to Figure 9 and Figure 10 The measurement circuit 104 includes four measurement interfaces, which are a first measurement interface 116 - 1 , a second measurement interface 116 - 2 , a third measurement interface 116 - 3 , and a fourth measurement interface 116 - 4 electrically connected to the four multi-way switches 103 .

[0092] The first measurement interface 116-1 is electrically connected to the resistor 118, the sinusoidal signal generator 119 and the fourth measurement interface 116-4 in sequence. A resistor-voltage amplifier 120 is connected in parallel to the resistor 118 and is electrically connected to a resistance-voltage analog-to-digital converter 122. The resistance-voltage analog-to-digital converter 122 is electrically connected to the microprocessor 123; the sinusoidal signal generator 119 is electrically connected to the microprocessor 123.

[0093] Both the second measurement interface 116-2 and the third measurement interface 116-3 are electrically connected to a soil voltage amplifier 117, which is electrically connected to a microprocessor 123 via a soil voltage analog-to-digital converter 121. The microprocessor 123 is signal-connected to a remote monitoring terminal via a data acquisition server 105. In this embodiment, the data acquisition server 105 includes a communication interface 124. The measurement circuit 104 can simultaneously acquire resistance voltage and soil voltage information, providing the basis for calculating the impedance modulus. The use of the microprocessor 123 and the remote monitoring terminal enables automated data processing and real-time transmission, significantly improving work efficiency.

[0094] In this embodiment, the multi-way switch 103 is a 64-choose-one switch circuit. If there are less than 64 electrodes, only a part of the design can be used, or corresponding simplification can be made. Specifically, the 64-choose-one switch circuit refers to Figure 11 , consisting of nine National Semiconductor MM74HC4051 chips, U1 to U9. Connectors N1 to N64 in the figure are connected to 64 BNC female connectors, which are then connected to the BNC female electrode array cable detector connector. Connectors A, B, C, E, D, and F are connected to the microprocessor 123. The sine signal generator 119 is a DDS integrated circuit, model AD9852, manufactured by Analog Devices, USA, with reference to Figure 12 The soil voltage amplifier 117 and the resistance voltage amplifier 120 use the same amplifier circuit, refer to Figure 13 UA1 is the integrated circuit DAC1210 produced by National Semiconductor Corporation of the United States, and UA2 is the integrated circuit AD811 produced by ANALOG DEVICES of the United States. A_IN is the analog input terminal, and A_OUT is the amplifier output terminal. A_D1-A_D10 are connected to the microprocessor 123 and are set to the gain size under the control of the microprocessor 123. The microprocessor 123 uses the integrated circuit TMS320F2812 produced by Texas Instruments of the United States, which integrates an analog-to-digital converter. Figure 14 , the microprocessor 123 is used to execute steps S2 to S4. Figure 14 ADC_IN1 is connected to the ground voltage amplifier 117, and ADC_IN2 is connected to the ground voltage amplifier resistor 118. DDS_A0-DDS_A5 and DDS_D0-DDS_D7 are control lines of the sine signal generator 119 and are connected to the sine signal generator 119. A_D1-A_D10 are connected to the programmable amplifier to control the gain of the programmable amplifier.

[0095] As a further solution of this embodiment, and The calculation method includes the following steps:

[0096] S3.1, set the frequency of the sine signal generator 119 to the first The sampling frequencies of the soil voltage analog-to-digital converter 121 and the resistance voltage analog-to-digital converter 122 are set to the first characteristic frequencies times;

[0097] S3.2, respectively obtain The output data of 100 soil voltage analog-to-digital converters 121 and resistance voltage analog-to-digital converters 122 are connected to the measuring electrodes. and , and calculate 100 and The absolute deviation value, and 100 and Deviation value of

[0098] S3.3 Calculation and ;

[0099]

[0100]

[0101] in, For 100 The sum of the absolute deviations of For 100 The sum of the absolute deviations of For 100 The sequence number of the negative zero crossing point in the deviation value; For 100 The sequence number of the negative zero crossing point in the deviation value. The sequence number of the negative zero crossing point is 100 in sequence. and The number of the deviation value that changes from positive to negative. For example: Suppose and )indivual The deviation values ​​are and , is a positive number, If it is a negative number, the sequence number of the negative zero crossing point is , is a natural number.

[0102] The method for obtaining calibration data is the same as that for measuring data, except that the serial number of the calibration test soil layer is added.

[0103] In this embodiment, the characteristic frequencies include impedance mode characteristic frequencies and phase characteristic frequencies corresponding to multiple calibrated soil moisture distribution layers. The method for obtaining the impedance mode characteristic frequency and phase characteristic frequency in each calibrated soil moisture distribution layer is:

[0104] The soil test column is installed in the soil layer corresponding to the soil moisture distribution, and the impedance mode mean square error and phase mean square error of all combinations of measuring electrodes at different frequencies are obtained. The frequency corresponding to the maximum value of all impedance mode mean square errors is taken as the impedance mode characteristic frequency of the soil layer corresponding to the soil moisture distribution, and the frequency corresponding to the maximum value of all phase mean square errors is taken as the impedance mode characteristic frequency of the soil layer corresponding to the soil moisture distribution.

[0105] As a further solution of this embodiment, The calculation method is: = .

[0106] in:

[0107]

[0108]

[0109]

[0110]

[0111]

[0112]

[0113] in, and Respectively The average impedance modulus and phase value of all combined measuring electrodes in a calibrated soil moisture distribution layer; is the total number of characteristic frequencies; that is ; K is the number of combinations of all measuring electrodes , ; and They are and The average value of .

[0114] Example 2

[0115] This embodiment is further limited on the basis of the embodiment 1. The specific improvement lies in proposing a method for producing a soil layer for calibrating the soil moisture distribution. For other parts not mentioned, refer to the embodiment 1 or the prior art.

[0116] This embodiment provides a method for calibrating soil moisture distribution layers, including the following steps:

[0117] (1) Extract soil samples from the test points of the monitoring soil layer;

[0118] (2) Dry the soil sample and grind it with a grinder;

[0119] (3) Take dried soil and water and mix them with a mixer;

[0120] (4) Place soil samples in multiple test chambers according to the uniform humidity and stratified humidity methods, and install humidity sensors. Use the humidity sensors to calibrate the soil moisture distribution of the two soil layers, uniform humidity and stratified humidity.

[0121] The test chamber measures 1 meter in length, width, and height. Uniform humidity means all soil has the same humidity. Stratified humidity means the humidity increases in layers from bottom to top.

[0122] In this embodiment, ten types of calibrated soil moisture distribution soil layers with uniform humidity of 5%, 10%, 15%, ..., and 50% were prepared respectively; a total of seven types of calibrated soil moisture distribution soil layers with stratified humidity were prepared, all of which were set in 20 cm thick layers. The stratified humidity is shown in Table 1:

[0123] Table 1 Layered humidity of soil layers for seven calibrated soil moisture distributions

[0124]

[0125] Therefore, this embodiment has a total of 17 calibrated soil moisture distribution layers, namely Calibration data and The acquisition method of is the same as that of the measurement data, except that the serial number of the calibration test soil layer is added.

[0126] In summary, the beneficial effects of this solution are:

[0127] The calibration experimental soil layer has stronger robustness. Even when environmental conditions change, the strategy can be quickly adjusted by comparing the calibration data to ensure the continuity and stability of the monitoring work, making it easier for experts to assess the accurate geological disaster warning level.

[0128] Although the specific embodiments of the invention are described in detail in conjunction with the accompanying drawings, this should not be construed as limiting the scope of protection of this patent. Within the scope described by the claims, various modifications and variations that can be made by those skilled in the art without creative work still fall within the scope of protection of this patent.

Claims

1. A single column soil moisture testing method, characterized in that: Including steps: S1. Install the soil test column in the monitoring soil layer; wherein, the soil test column is provided with Each soil electrode is electrically connected to the four measurement interfaces in the measurement circuit through four multi-way switches. is a natural number greater than or equal to 4; S2. Place the soil in the test column. The soil electrodes are sorted and numbered respectively, and grouped into groups of 4 adjacent soil electrodes. Soil electrodes are divided into a set of measuring electrodes; S3. The measurement data of all measuring electrodes in the monitored soil layer at different characteristic frequencies are obtained through the measurement circuit. The measurement data include and ;in, For the The measuring electrodes are The measured impedance modulus is obtained at the characteristic frequency , For the The measuring electrodes are The measured phase at the characteristic frequency ; S4. Calculate the correlation coefficient between the measured data and the calibration data; The calibration data includes and , For the The first soil layer in the calibrated soil moisture distribution The measuring electrodes are The calibrated impedance modulus obtained by the characteristic frequency; For the The first soil layer in the calibrated soil moisture distribution The measuring electrodes are The calibration phase obtained at the characteristic frequency; the correlation coefficient includes 、 and , For the Calibrated soil moisture distribution in soil layers and Impedance modulus correlation coefficient between ; For the Calibrated soil moisture distribution in soil layers and The phase correlation coefficient between For the The comprehensive correlation coefficient between the calibrated soil moisture distribution soil layer and the measured data is obtained through and Calculated; S5. Acquisition The maximum value in , will be with The corresponding calibrated soil moisture distribution soil layer is used as the actual soil moisture distribution soil layer of the monitoring soil layer; S6. Based on the actual soil moisture content, soil layer distribution and geological structure of the monitored soil layer, the geological disaster warning level of the monitored soil layer is given by expert evaluation.

2. The single column soil moisture testing method according to claim 1, characterized in that: The soil test column includes a cylindrical shell, a conical bottom, a top cover, a filling layer, an electrode sandwich between the inner wall of the shell and the outer wall of the filling layer, and a Soil electrodes, One end of each soil electrode passes through multiple measuring holes on the shell and contacts the soil. The other end of each soil electrode is electrically connected to a measuring circuit located on the filling layer through an electrode connecting wire.

3. The single column soil moisture testing method according to claim 2, characterized in that: A plurality of guide grooves are provided on the inner wall of the shell along the height direction, and a flange which is slidably matched with the plurality of guide grooves is provided on the outer wall of the filling layer.

4. The single column soil moisture testing method according to claim 2, characterized in that: A plurality of fixing holes for the lock buckles to pass through are provided on the outer wall of the conical structure at the bottom of the shell, and a plurality of guide holes are vertically provided inside the filling layer. The bottoms of the plurality of guide holes are curved and respectively connected to the plurality of fixing holes, and the tips of the plurality of lock buckles respectively enter the plurality of guide holes and drill out from the plurality of fixing holes into the soil.

5. The single column soil moisture testing method according to claim 2, characterized in that: The multiple measuring holes on the shell are evenly divided into multiple layers along the height direction, and the multiple measuring holes on each layer are distributed in a circular pattern.

6. The single column soil moisture testing method according to claim 2, characterized in that: A fixing plate for fixing the measuring circuit with bolts is provided on the top of the filling layer, and a connecting wire through-hole for passing a plurality of electrode connecting wires is provided in the middle of the fixing plate.

7. The single column soil moisture testing method according to claim 1, characterized in that: The measurement circuit includes four measurement interfaces, which are respectively a first measurement interface, a second measurement interface, a third measurement interface, and a fourth measurement interface electrically connected to four multi-way switches; The first measurement interface is electrically connected to the resistor, the sinusoidal signal generator, and the fourth measurement interface in sequence. The resistor is connected in parallel with a resistor-voltage amplifier electrically connected to a resistor-voltage analog-to-digital converter. The resistor-voltage analog-to-digital converter is electrically connected to a microprocessor. The sinusoidal signal generator is electrically connected to the microprocessor. The second measurement interface and the third measurement interface are both electrically connected to the soil voltage amplifier, and the soil voltage amplifier is electrically connected to the microprocessor through a soil voltage analog-to-digital converter; the microprocessor is connected to the remote monitoring terminal signal through the communication interface.

8. The single column soil moisture testing method according to claim 7, characterized in that: and The calculation method includes the following steps: S3.1, set the frequency of the sine signal generator to the first The sampling frequencies of the soil voltage analog-to-digital converter and the resistance voltage analog-to-digital converter are set to characteristic frequencies times; S3.2, respectively obtain The output data of 100 soil voltage analog-to-digital converters and resistance voltage analog-to-digital converters are connected to the measuring electrodes. and , and calculate 100 and The absolute deviation value, and 100 and Deviation value of S3.3 Calculation and ; in, For 100 The sum of the absolute deviations of For 100 The sum of the absolute deviations of For 100 The sequence number of the negative zero crossing point in the deviation value; For 100 The sequence number of the negative zero crossing point in the deviation value.

9. The single column soil moisture testing method according to claim 8, characterized in that: The characteristic frequencies include impedance mode characteristic frequencies and phase characteristic frequencies corresponding to multiple calibrated soil moisture distribution layers. The method for obtaining the impedance mode characteristic frequencies and phase characteristic frequencies in each calibrated soil moisture distribution layer is as follows: The soil test column is installed in the soil layer corresponding to the soil moisture distribution, and the impedance mode mean square error and phase mean square error of all combinations of measuring electrodes at different frequencies are obtained. The frequency corresponding to the maximum value of all impedance mode mean square errors is taken as the impedance mode characteristic frequency of the soil layer corresponding to the soil moisture distribution, and the frequency corresponding to the maximum value of all phase mean square errors is taken as the impedance mode characteristic frequency of the soil layer corresponding to the soil moisture distribution.

10. The single column soil moisture testing method according to claim 9, characterized in that: The calculation method is: = in, and Respectively The average impedance modulus and phase value of all combined measuring electrodes in a calibrated soil moisture distribution layer; is the total number of characteristic frequencies; K is the number of combinations of all measuring electrodes ; and They are and The average value of .

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