Dual column soil moisture test method

Abstract

The application discloses a double-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 measurement method cannot accurately warn geological disasters due to only taking resistance as an index. The application carries out impedance spectrum measurement and resistance measurement on the soil layer through multiple electrode pairs, obtains impedance spectrum and resistance, the impedance spectrum includes impedance modulus and phase, and more abundant information can be provided. Meanwhile, the two soil testing columns are symmetrically arranged on the left and right, the distance between the two columns provides a larger horizontal span, so that the data measured by the electrode pairs between the two columns can better represent the average condition of the whole monitoring area. The comprehensive correlation coefficient is obtained by comprehensively calculating the resistance correlation coefficient, the impedance modulus correlation coefficient and the phase correlation coefficient, so that the closest calibrated soil moisture content distribution soil layer to the monitoring soil layer can be more accurately determined.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of soil moisture content testing, and particularly relates to a double-column soil moisture content testing method. BACKGROUND

[0002] Soil moisture content refers to the amount of water contained in a unit volume or weight of soil, which is one of the key factors affecting plant growth, soil physical properties and ecological processes. Accurate measurement of soil moisture content is of great significance for agricultural irrigation management, water resource protection, environmental protection and geological disaster warning.

[0003] In the prior art, soil moisture content measurement methods often rely on resistance measurement. The principle is that water increases the soil conductivity, and the resistance decreases. For example, the patent for invention with publication number CN111257374B discloses a soil moisture content and nitrogen content monitoring method, device, equipment and storage medium, which includes the steps of: inputting the voltage value, resistance value and capacitance value into the soil moisture content and nitrogen content prediction model, and outputting the corresponding moisture content and nitrogen content of the soil to be measured; wherein, the voltage value, resistance value and capacitance value of the monitored soil sample are used as training samples, and the moisture content and nitrogen content corresponding to the soil sample are used as training labels for training.

[0004] Although the invention obtains soil moisture content through resistance value, it has the problem of inaccuracy. Soil is a multiphase system containing solid, liquid and gaseous states. Resistance can only reflect the overall resistance encountered by the current and cannot distinguish different forms of water, which limits its accuracy. Specifically, first, the relationship between soil resistivity and moisture content is nonlinear and affected by soil type. For example, in sandy soil, the change of water content has little effect on resistance; while in clay, a small change in water content can cause significant fluctuations in resistivity. Temperature also affects resistance measurement results because it changes the ion migration rate. Second, soil is composed of minerals, air, water, organic matter, etc., and these components will affect the electrical properties. Therefore, resistance changes may be the result of the combined action of multiple factors, not just changes in moisture content, so using resistance as an indicator alone is not enough to accurately reflect soil moisture content, and thus cannot accurately warn of geological disasters. SUMMARY

[0005] In view of the above problems in the prior art, the present application provides a double-column soil moisture content testing method, which solves the problem that the existing soil moisture content measurement method cannot accurately warn of geological disasters due to using resistance as the only indicator.

[0006] In order to achieve the above purpose, the technical scheme adopted by the present application is as follows:

[0007] A double-column soil moisture content testing method is provided, characterized by comprising the steps of:

[0008] S1. Two soil test columns are fixed symmetrically in the monitored soil layer; wherein, two adjacent sides of the two soil test columns are provided with multiple soil electrodes connected to the soil moisture measurement circuit through a wire selection circuit, and the soil moisture measurement circuit is remotely communicated with the host computer.

[0009] S2. Pair all soil electrodes into electrode pairs, number all electrode pairs and the measurement frequency points of the impedance spectrum measurement circuit in the soil moisture measurement, and use the host computer to make the soil moisture measurement circuit turn on one of the electrode pairs through the wire selection circuit.

[0010] S3. The impedance spectrum measurement circuit and the bridge measurement circuit in the soil moisture measurement circuit are used to respectively measure the impedance spectrum and the phase between the selected conductive electrode pairs, where the impedance spectrum includes an impedance modulus and a phase.

[0011] S4, repeat steps S2 to S3 until all electrode pairs are measured and the 、 and ,in, For the number The resistance between the electrode pairs, and They are numbered The electrode pairs and the frequency points are numbered Impedance modulus and phase.

[0012] S5. According to 、 and Calculate the correlation coefficient with the calibration data.

[0013] Calibration data includes 、 and ,in, For the The soil moisture content distribution in the calibrated soil layer is numbered as The resistance between the electrode pairs, and Respectively The soil moisture content distribution in the calibrated soil layer is numbered as The electrode pairs and the frequency points are numbered Impedance modulus and phase.

[0014] The correlation coefficient includes 、 、 and ; 、 and They are and The resistance correlation coefficient between and The impedance modulus correlation coefficient between and The phase correlation coefficient between pass 、 and Calculated to monitor the soil layer and the The comprehensive correlation coefficient of the calibrated soil moisture distribution soil layers.

[0015] S6. Acquisition The maximum value , 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.

[0016] S7. Based on the actual soil moisture content, distribution of soil layers and geological structure of the monitored soil layer, the geological disaster warning level of the monitored soil layer is given by expert evaluation.

[0017] In this scheme, by arranging two soil test columns symmetrically, and selecting two soil electrodes on the two soil test columns for impedance spectrum measurement and resistance measurement, the impedance spectrum and resistance are obtained. The impedance spectrum includes the impedance mode and phase, which can provide richer information. At the same time, because the two soil test columns are arranged symmetrically, the distance between them provides a larger horizontal span, so that the data measured by the cross-electrode pairs between them can better represent the average conditions of the entire monitoring area. In addition, the comprehensive correlation coefficient of this scheme is obtained by combining the resistance correlation coefficient, the impedance mode correlation coefficient, and the phase correlation coefficient. It is more convenient to determine the calibration soil moisture distribution layer that is closest to the monitored soil layer. The calibration soil moisture distribution layer is the benchmark value set for the calibration experiment. Considering the complex and changeable conditions of the actual monitored soil layer, 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 to ensure the continuity and stability of the monitoring work, which facilitates experts to assess the accurate geological disaster warning level.

[0018] Furthermore, each soil testing column includes a cylindrical outer shell with a conical bottom, a top cover, a filling layer within the shell, and an electrode sandwich between the inner wall of the shell and the outer wall of the filling layer. Multiple soil electrodes are fixed to one side of the electrode sandwich. One end of each soil electrode passes through multiple measurement holes on one side of the outer wall of the shell to contact the soil. The other ends of each soil electrode are connected to the soil moisture measurement circuit via electrode connecting wires. The soil testing column is easy to install and maintain, ensuring the stability and repeatability of measurement results.

[0019] Furthermore, the inner wall of each 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, helping to reduce errors caused by device movement, and enhancing the reliability of test results.

[0020] Furthermore, the outer wall of the conical structure at the bottom of each housing is provided with multiple fixing holes for the locking clips to pass through. Multiple guide holes are vertically arranged inside the filling column. The bottoms of these 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.

[0021] Furthermore, multiple measurement holes on two adjacent sides of the two housings are evenly spaced along the height direction. This even distribution of measurement holes ensures consistency in the soil contact area of ​​each electrode, thereby improving the comparability of soil moisture measurements at different depths.

[0022] Furthermore, a fixing plate for fixing the soil moisture measurement 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.

[0023] Furthermore, the soil moisture measurement circuit includes three wire gating circuits, each of which includes a first wire gating circuit, a second wire gating circuit, and a third wire gating circuit, all connected to a microprocessor. The second and third wire gating circuits are respectively connected to a bridge measurement circuit and an impedance spectrum measurement circuit, each of which is connected to the first wire gating circuit. The first wire gating circuit is used to selectively conduct multiple soil electrodes located on the left soil test column, while the second and third wire gating circuits are used to selectively conduct multiple soil electrodes located on the right soil test column. The three wire gating circuits allow for selective conduction of different combinations of soil electrodes. Combined with the bridge measurement circuit and the impedance spectrum measurement circuit, this circuit achieves precise measurement of soil moisture between selected electrodes, enhancing system flexibility and adaptability to meet diverse measurement needs.

[0024] Furthermore, The calculation method is:

[0025]

[0026]

[0027]

[0028] in, It is the average resistance measured by all electrode pairs in the monitored soil layer; for The product of is the total number of soil electrodes in a soil test column; For the The average resistance measured by all electrode pairs in a calibrated soil moisture distribution layer.

[0029] Furthermore, The calculation method is:

[0030]

[0031]

[0032]

[0033] in, It is the average value of the impedance modulus measured by all electrode pairs in the monitoring soil layer; for The product of is the total number of soil electrodes in a soil test column; is the total number of frequency points in the impedance spectrum measurement circuit; For the The impedance modulus average value of all electrode pairs in the calibration soil moisture content distribution soil layer.

[0034] Further, The calculation method is:

[0035]

[0036]

[0037]

[0038] Wherein, The phase average value of all electrode pairs in the calibration soil moisture content distribution soil layer is monitored. The product of The total number of soil electrodes in a soil test column; The total number of frequency points in the impedance spectrum measurement circuit; The phase average value of the first The phase average value of all electrode pairs in the calibration soil moisture content distribution soil layer.

[0039] The application discloses a double-column soil moisture content testing method, which has the beneficial effects that:

[0040] The application obtains impedance spectrum and resistance by symmetrically arranging two soil test columns and selecting two soil electrodes on the two soil test columns for impedance spectrum measurement and resistance measurement, the impedance spectrum includes impedance modulus and phase, and can provide more abundant information, and since the two soil test columns are symmetrically arranged, the distance between the two soil test columns provides a larger horizontal span, so that the data measured by the electrode pairs between the two soil test columns can better represent the average condition of the entire monitoring area. The comprehensive correlation coefficient is obtained by comprehensively calculating the resistance correlation coefficient, the impedance modulus correlation coefficient and the phase correlation coefficient, and can better determine the calibration soil moisture content distribution soil layer closest to the monitoring soil layer. BRIEF DESCRIPTION OF DRAWINGS

[0041] Figure 1 The flowchart of the double-column soil moisture content testing method is shown in the figure;

[0042] Figure 2 The structural diagram of the two soil test columns is shown in the figure;

[0043] Figure 3 The internal structure diagram of the soil test column is shown in the figure;

[0044] Figure 4 The structural diagram of the shell is shown in the figure;

[0045] Figure 5 The cross-sectional view of the shell is shown in the figure; ​

[0046] Figure 6 Schematic diagram of the structure of the electrode interlayer;

[0047] Figure 7 Schematic diagram of the structure of the soil electrode;

[0048] Figure 8 is a top view of the filling layer;

[0049] Figure 9 is the internal schematic diagram of the filling layer;

[0050] Figure 10 is a structural diagram of the fixed plate;

[0051] Figure 11 This is the circuit diagram of the soil moisture measurement circuit;

[0052] Figure 12 A circuit diagram for a wire gating circuit;

[0053] Figure 13 This is the circuit diagram of the impedance spectrum measurement circuit;

[0054] Figure 14 This is the circuit diagram of the bridge measurement circuit;

[0055] Among them: 1. Shell; 5. Electrode interlayer; 7. Soil electrode; 8. Electrode connecting wire; 9. Conductor; 12. Impedance spectrum measurement circuit; 13. Bridge measurement circuit; 14. Microprocessor; 15. Communication interface; 16. Power supply circuit; 30. Filling layer; 40. Fixing plate; 50. Top cover. DETAILED DESCRIPTION

[0056] 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.

[0057] Example 1

[0058] This embodiment provides a dual-column soil moisture testing method, which aims to solve the problem that existing soil moisture measurement methods cannot accurately reflect soil moisture because they only use resistance as an indicator. It will be demonstrated in detail below.

[0059] A double column soil moisture test method, reference Figure 1 , including the steps of:

[0060] S1. Reference Figure 2, two soil test columns are fixed symmetrically in the monitored soil layer; wherein, a plurality of soil electrodes 7 are provided on two adjacent sides of the two soil test columns, each of which is connected to the soil moisture measurement circuit through a wire gating circuit, and the soil moisture measurement circuit is remotely communicated with the host computer.

[0061] S2. Pair all soil electrodes 7 into electrode pairs, number all electrode pairs and the measurement frequency points of the impedance spectrum measurement circuit 12 in soil moisture measurement, and use the host computer to make the soil moisture measurement circuit turn on one of the electrode pairs through the wire selection circuit.

[0062] In this implementation, the symmetrical placement of the two soil test columns provides a greater horizontal span, making the data measured by the straddling electrode pairs more representative of the average conditions across the entire monitoring area. This dual-column measurement also expands the current path, reducing the impact of local anomalies on overall measurement results and improving data accuracy and stability.

[0063] S3. The impedance spectrum measurement circuit 12 and the bridge measurement circuit 13 in the soil moisture measurement circuit respectively measure the impedance spectrum and phase between the selected conductive electrode pairs, where the impedance spectrum includes an impedance modulus and a phase.

[0064] S4, repeat steps S2 to S3 until all electrode pairs are measured and the 、 and ,in, For the number The resistance between the electrode pairs, and They are numbered The electrode pairs and the frequency points are numbered The impedance magnitude and phase of

[0065] S5. According to 、 and Calculate the correlation coefficient with the calibration data.

[0066] Calibration data includes 、 and ,in, For the The soil moisture content distribution in the calibrated soil layer is numbered as The resistance between the electrode pairs, and Respectively The soil moisture content distribution in the calibrated soil layer is numbered The electrode pairs and the frequency points are numbered The impedance magnitude and phase of

[0067] The correlation coefficient includes 、 、 and ; 、 and They are and The resistance correlation coefficient between and The impedance modulus correlation coefficient between and The phase correlation coefficient between pass 、 and Calculated to monitor the soil layer and the The comprehensive correlation coefficient of the calibrated soil moisture distribution soil layers.

[0068] S6. Acquisition The maximum value , 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.

[0069] S7. Based on the actual soil moisture content, distribution of soil layers and geological structure of the monitored soil layer, the geological disaster warning level of the monitored soil layer is given by expert evaluation.

[0070] As a further solution of this embodiment, The calculation method is:

[0071]

[0072]

[0073]

[0074] in, It is the average resistance measured by all electrode pairs in the monitored soil layer; for The product of is the total number of soil electrodes in a soil test column; For the The average resistance measured by all electrode pairs in a calibrated soil moisture distribution layer.

[0075] The calculation method is:

[0076]

[0077]

[0078]

[0079] wherein, is the average impedance modulus measured by all electrode pairs in the monitoring soil layer; is the total number of frequency points in the impedance spectrum measurement circuit; is the average impedance modulus measured by the th electrode pair in the calibration soil moisture distribution layer.

[0080] The calculation method is:

[0081]

[0082]

[0083]

[0084] wherein, is the average phase measured by all electrode pairs in the monitoring soil layer; is the average phase measured by the th electrode pair in the calibration soil moisture distribution layer.

[0085] The calculation method is: .

[0086] The comprehensive correlation coefficient is calculated by comprehensively calculating the resistance correlation coefficient, the impedance modulus correlation coefficient and the phase correlation coefficient, which is more convenient to determine the calibration soil moisture distribution layer closest to the monitoring soil layer. The calibration soil moisture distribution layer is the reference value set by the calibration experiment. Considering the complex and variable conditions of the actual monitoring soil layer, the calibration experiment soil layer has stronger robustness. Even when the environmental conditions change, the strategy can be quickly adjusted through comparison of the calibration data to ensure the continuity and stability of the monitoring work, and it is convenient for experts to assess the accurate geological disaster warning level.

[0087] Specifically, referring to Figure 3 , as the specific structure of the soil test column, each soil test column includes an outer shell 1, an electrode sandwich layer 5, a plurality of soil electrodes 7, a filling layer 30, a fixing plate 40 and a top cover 50.

[0088] The outer shell 1, referring to Figure 4. 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 by a casting process. A plurality of circular measuring holes are provided on the outer wall surface of the cylindrical structure. The plurality of measuring holes on the outer shell 1 are evenly spaced along the height direction, and the plurality of measuring holes on the two soil test columns are symmetrically arranged. The measuring holes are evenly distributed in the height direction, which ensures the consistency of the soil contact area of ​​the soil electrode 7 in each measuring hole, thereby improving the comparability between the measured values ​​of soil moisture content at different depths. Reference Figure 4 ,in Figure 4 2-1, 2-2, 2-3 and 2-N are all measuring holes.

[0089] The outer wall of the conical structure at the bottom of the housing 1 is provided with a plurality of fixing holes for the lock to pass through. 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 housing 1. The distance between adjacent measuring holes is 120 degrees. Figure 4 ,in Figure 4 3-1 and 3-2 are both fixing holes.

[0090] Electrode sandwich 5, reference Figure 6 The electrode interlayer 5 is a cylindrical structure made of insulating material. In this embodiment, polytetrafluoroethylene is used. The outer diameter of the electrode interlayer 5 is smaller than the inner diameter of the upper half of the shell 1, so that the electrode interlayer 5 can be inserted into the shell 1 and fit tightly against the shell 1. The height of the electrode interlayer 5 is slightly higher than the height of the uppermost and lowermost measuring holes. An electrode mounting hole is opened at the position of the measuring hole corresponding to the shell 1. Figure 6 , where 6-1, 6-2, 6-3 and 6-N in the figure are electrode mounting holes.

[0091] The electrode mounting holes can be circular, with a radius less than 0.8 times the radius of the measuring hole in the housing 1. Multiple soil electrodes 7 are fixed to the electrode interlayer 5 through the electrode mounting holes. One end of each of the soil electrodes 7 passes through the multiple measuring holes in the housing 1 to contact the soil. The other ends of each of the soil electrodes 7 are electrically connected to the soil moisture measurement circuit via electrode connecting wires 8.

[0092] Soil electrode 7, reference Figure 7 The soil electrode 7 is circular and smaller than the electrode mounting hole. It is glued to the electrode mounting hole. One end of the soil electrode 7 is connected to the electrode connecting wire 8. The electrode connecting wire 8 is a connecting wire with a conductor 9 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 with a screw. The electrode connecting wire 8 is led out from the top, passes through the connecting wire hole from the top, and is fixed to the electrode connector. The electrode connector is electrically connected to the wire selection circuit via a connecting cable.

[0093] The filling layer 30, refer to Figure 9 The filling layer 30 is made of engineering plastic, which is the same shape as the inside of the shell 1, and is installed in the shell 1 to fix the electrode sandwich 5 in the shell 1. The inside of the filling layer 30 is vertically provided with a plurality of guide holes, the bottoms of the plurality of guide holes are each curvedly provided and respectively communicate with a plurality of fixing holes, the tips of a plurality of locks respectively enter the plurality of guide holes and drill out of the plurality of fixing holes into the soil. The lock is a strip-shaped cylinder with a pointed head; the lock is used to pass through the guide hole and embed into the soil, and the material used has good stress and certain deformation capacity. Refer to Figure 9 , Figure 9 31-1 in the above is a guide hole. The design of the fixing hole on the outer wall of the conical structure and the guide hole and the lock inside makes the whole device firmly embedded in the soil, and can remain stable even in soft or slippery ground conditions. For long-term monitoring, the lock can prevent data deviation caused by equipment displacement

[0094] In order to facilitate the filling layer 30 to be installed in the shell 1, refer to 5 and Figure 8 A plurality of guide grooves are provided on the inner wall of the shell 1 along the height direction, and a flange is provided on the outer wall of the filling layer 30 to slidably cooperate with the plurality of guide grooves. Figure 8 32-1, 32-2, 32-3 and 32-4 in the above are flanges, Figure 5 4-1, 4-2, 4-3 and 4-4 in the above are guide grooves. The design of the guide groove and the flange makes the filling layer 30 slide up and down in the shell 1 without rotating, ensuring the consistency of the position of the soil electrode 7, improving the measurement accuracy, helping to reduce the error caused by the movement of the device, and enhancing the reliability of the test results. The guide hole of the present embodiment is three, and is arranged in a circular shape with an interval of °.

[0095] The fixing plate 40, refer to Figure 10 The fixing plate 40 is located at the top of the filling layer 30, and is used to bolt fix the measuring circuit. The middle part of the fixing plate 40 is provided with a connection line perforation for a plurality of electrode connection lines 8 to pass through. The fixing plate 40 is a disc structure, the outer side is an external thread, and the external thread matches with the internal thread on the inner side of the top of the shell 1; the fixing plate 40 is fixed on the top of the shell 1 by the outer side external thread and the inner side internal thread on the top of the shell 1. The fixing plate 40 has four circuit board fixing holes for installing the circuit board of the soil humidity measuring circuit. Refer to Figure 10 , Figure 10 42-1, 42-2, 42-3 and 42-4 in the above are circuit board fixing holes.

[0096] The top cover 50, refer to Figure 3 The top cover 50 matches with the external thread on the top of the shell 1, and is used to be installed on the top of the shell 1 and seal the shell 1.

[0097] This embodiment provides a method for installing two soil testing columns, including the following steps:

[0098] Step 1: Place the electrode interlayer 5 on the filling layer 30 and install it into the housing 1; when inserting, the soil electrode 7 corresponds to the measuring hole of the housing 1 and is concentric with the soil electrode 7, and the soil electrode 7 does not touch the housing 1;

[0099] Step 2: Use a hammer to hammer the shell 1 into the monitored soil layer;

[0100] Step 3: With the pointed ends of the three lock buckles facing downward, 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.

[0101] Step 4: Pass the connecting wire 9 through the connecting wire hole and install it to the electrode connector; and install the fixing plate 40 on the housing 1.

[0102] Step 5: Connect the electrode connector to the circuit board;

[0103] Step 6: Mount the circuit board of the measuring circuit onto the fixing plate 40;

[0104] Step 7: Install the top cover 50 onto the housing 1;

[0105] Step 8: Repeat steps 1 to 8 to symmetrically fix the two soil test columns in the monitoring soil.

[0106] Specifically, as a specific circuit of the soil moisture measurement circuit of this embodiment, refer to Figure 12 The soil moisture measurement circuit includes three wire gating circuits, each of which includes a first wire gating circuit, a second wire gating circuit, and a third wire gating circuit, each of which is connected to the microprocessor 14. The microprocessor 14 is electrically connected to the power supply circuit 16.

[0107] The second and third wire gating circuits are connected to the bridge measurement circuit 13 and the impedance spectrum measurement circuit 12, respectively. Both the bridge measurement circuit 13 and the impedance spectrum measurement circuit 12 are connected to the first wire gating circuit. The first wire gating circuit is used to selectively conduct the multiple soil electrodes 7 located on the left soil test column; the second and third wire gating circuits are used to selectively conduct the multiple soil electrodes 7 located on the right soil test column. The three wire gating circuits allow for selective conduction of different combinations of soil electrodes 7. Combined with the bridge measurement circuit 13 and the impedance spectrum measurement circuit 12, this allows for precise measurement of soil moisture between selected electrodes, enhancing system flexibility and adaptability to meet diverse measurement needs.

[0108] refer to Figure 11 ,Figure 12 11-1, 11-2 and 11-3 are first, second and third wire selection circuits respectively, and the microprocessor 14 is connected with the first, second and third wire selection circuits through the control cable respectively, Figure 11 17-1, 17-2 and 17-3 are control cables.

[0109] Preferably, the first wire selection circuit is used for selecting the left soil electrode, and the second and third wire selection circuits are used for selecting the right soil electrode. Wherein, Figure 2 2-L1, 2-L2, 2-L3 and 2-LN are left soil electrodes, and 2-R1, 2-R2, 2-R3 and 2-RN are right soil electrodes, i.e. the value of N in this embodiment is 4.

[0110] In this embodiment, the communication interface 15 adopts the M905R-433 wireless transparent transmission module of Zhengzhou Yiling Electronics Technology Co., Ltd., and the microprocessor 14 chip adopts the microprocessor 14 of Atmel Company AR91RM9200 type. The impedance spectrum measurement circuit therein can refer to the impedance spectrum measurement circuit in the invention patent with the publication number CN103105418B, the concrete monitoring and detecting instrument with steel bars as electrodes and the monitoring and detecting method thereof.

[0111] Reference Figure 12 The first, second and third wire selection circuits are composed of 7 chips MM74HC4051 of the United States National Semiconductor Company, U1~U7, and 1 chip MM74HC4052 of the United States National Semiconductor Company, U8. A1, B1, C1, A2, B2, C2, A3, B3, C3, A4, B4, C4, A5, B5, C5, A6, B6, C6, A7, B7 in the figure are connected with the microcontroller to control the input address code; 54-a and 54-b are respectively short-circuited with 55-a and 55-b of the bridge measurement circuit 13, or are respectively short-circuited with POLE1 and POLE2 of the impedance spectrum measurement circuit 12.

[0112] The impedance spectrum measurement circuit 12 refers to Figure 13 The chip of the impedance spectrum measurement circuit 12 is the chip AD5933 of the United States Analog Devices, Inc. Figure 13 POLE1 and POLE2 are short-circuited with 54-a and 54-b. SCL and SDA are connected with the impedance measurement control interface of the measurement control microprocessor 14.

[0113] The bridge measurement circuit 13 refers to Figure 14 , Figure 14The 55-a, 55-b in the figure are short-circuited with 54-A, 54-A in the figure; 57 interface is short-circuited with the microprocessor 14, wherein Figure 14 The two clock signals CLK-1 and CLK-2 in the figure are provided by the microprocessor 14.

[0114] Embodiment 2

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

[0116] This embodiment gives the making method of the calibration soil moisture distribution soil layer, which comprises the following steps:

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

[0118] (2) Dry the soil samples and grind them with a grinder;

[0119] (3) Take the dried soil and water, and stir them with a blender;

[0120] (4) Put the soil samples into multiple test boxes in the way of uniform humidity and layered humidity, and install humidity sensors according to the two types of calibration soil moisture distribution soil layers of uniform humidity and layered humidity completed by the humidity sensors.

[0121] Among them, the length, width and height of the test box are all 1 meter. The uniform humidity represents that all the soil is of one humidity. The layered humidity represents that the humidity is layered and increased in the direction from bottom to top.

[0122] In this embodiment, calibration soil moisture distribution soil layers with uniform humidities of 5%, 10%, 15%, …, and 50% are made, a total of ten; calibration soil moisture distribution soil layers with layered humidities are 7, which are all set in layers of 20 centimeters thick, and the layered humidities are shown in Table 1:

[0123] Table 1 Layered humidities of 7 calibration soil moisture distribution soil layers

[0124]

[0125] Therefore, this embodiment has a total of 17 calibration soil moisture distribution soil layers, i.e. .

[0126] Although the specific embodiments of the invention are described in detail with reference to the accompanying drawings, it should not be understood as limiting the protection scope of the patent. Various modifications and variations made by those skilled in the art within the scope described in the claims are still within the protection scope of the patent.

Claims

1. Double-column soil moisture test method, characterized in that: Including steps: S1. Two soil test columns are fixed symmetrically in the monitored soil layer; wherein, two adjacent sides of the two soil test columns are each provided with a plurality of soil electrodes connected to a soil moisture measurement circuit via a wire gating circuit, and the soil moisture measurement circuit is remotely connected to a host computer; S2. Pair all soil electrodes into electrode pairs, number all electrode pairs and the measurement frequency points of the impedance spectrum measurement circuit in the soil moisture measurement, and use the host computer to make one of the electrode pairs of the soil moisture measurement circuit conductive through the wire gating circuit; S3, measuring the impedance spectrum and phase between the selected conductive electrode pairs using the impedance spectrum measurement circuit and the bridge measurement circuit in the soil moisture measurement circuit, respectively, where the impedance spectrum includes an impedance modulus and a phase; S4, repeat steps S2 to S3 until all electrode pairs are measured and the 、 and ,in, For the number The resistance between the electrode pairs, and They are numbered The electrode pairs and the frequency points are numbered Impedance modulus and phase; S5. According to 、 and Calculate the correlation coefficient with the calibration data; Calibration data includes 、 and ,in, For the The soil moisture content distribution in the calibrated soil layer is numbered as The resistance between the electrode pairs, and Respectively The soil moisture content distribution in the calibrated soil layer is numbered as The electrode pairs and the frequency points are numbered Impedance modulus and phase; The correlation coefficient includes 、 、 and ; 、 and They are and The resistance correlation coefficient between and The impedance modulus correlation coefficient between and The phase correlation coefficient between pass 、 and Calculated to monitor the soil layer and the Comprehensive correlation coefficient of the calibrated soil moisture distribution soil layer; S6. Acquisition The maximum value , 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; S7. Based on the actual soil moisture content, distribution of soil layers 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 double-column soil moisture testing method according to claim 1, characterized in that: 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 multiple soil electrodes are fixed on one side of the electrode sandwich. One end of the multiple soil electrodes respectively passes through multiple measuring holes on the outer wall of one side of the shell to contact the soil, and the other ends of the multiple soil electrodes are connected to the soil moisture measurement circuit through electrode connecting wires.

3. The double-column soil moisture testing method according to claim 2, characterized in that: A plurality of guide grooves are provided on the inner wall of each 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 double-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 each shell, and a plurality of guide holes are vertically provided inside the filling column. The bottoms of the plurality of guide holes are bent and respectively connected with 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 double-column soil moisture testing method according to claim 2, characterized in that: The plurality of measuring holes on two adjacent side surfaces of the two shells are evenly spaced and distributed along the height direction.

6. The double-column soil moisture testing method according to claim 2, characterized in that: A fixing plate for fixing the soil moisture measurement 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 double-column soil moisture testing method according to claim 2, characterized in that: The soil moisture measurement circuit includes three wire gating circuits, each of which includes a first wire gating circuit, a second wire gating circuit, and a third wire gating circuit, all of which are connected to the microprocessor; The second wire gating circuit and the third wire gating circuit are connected to the bridge measurement circuit and the impedance spectrum measurement circuit respectively, and the bridge measurement circuit and the impedance spectrum measurement circuit are both connected to the first wire gating circuit; Among them, the first wire gating circuit is used to select and conduct multiple soil electrodes located on the left soil test column; the second wire gating circuit and the third wire gating circuit are both used to select and conduct multiple soil electrodes located on the right soil test column.

8. The double-column soil moisture testing method according to claim 1, characterized in that: The calculation method is: in, It is the average resistance measured by all electrode pairs in the monitored soil layer; for The product of is the total number of soil electrodes in a soil test column; For the The average resistance measured by all electrode pairs in a calibrated soil moisture distribution layer.

9. The double-column soil moisture testing method according to claim 1, characterized in that: The calculation method is: in, It is the average value of the impedance modulus measured by all electrode pairs in the monitoring soil layer; for The product of is the total number of soil electrodes in a soil test column; is the total number of frequency points in the impedance spectrum measurement circuit; For the The average value of the impedance modulus measured by all electrode pairs in a calibrated soil moisture distribution layer.

10. The double-column soil moisture testing method according to claim 1, characterized in that: The calculation method is: in, It is the average phase value measured by all electrode pairs in the monitored soil layer; for The product of is the total number of soil electrodes in a soil test column; is the total number of frequency points in the impedance spectrum measurement circuit; For the The average phase value measured by all electrode pairs in a calibrated soil moisture distribution layer.

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