CN103472127B - Unsaturated soil soil water characteristic Quantitative detection sensor and application thereof - Google Patents

Abstract

The sensor for rapid quantitative detection of unsaturated soil-water characteristics of the present invention is provided with a coupling coil at one end of a completely sealed and waterproof casing, and at the other end with a junction box including a power supply input end and a detection signal output end; an AC/DC conversion circuit is arranged inside the casing And the following CV, the module composed of ACVG plus IA is connected to the module composed of acv/dcv plus VA; acv/dcv is connected to the output terminal of the detection signal; the sensor connects a 100MHz AC current in the coupling coil to generate a high stability , Micro-extra-level AC magnetic field, and then activate the charged particles of soil water in the unsaturated soil to polarize it, thereby forming a microelectronic current, which is detected by the detection circuit. It can be used for real-time observation indoors and outdoors. It has the advantages of fast, sensitive, small error and small volume.

Description

Rapid Quantitative Detection Sensor for Unsaturated Soil Water Characteristics and Its Application

technical field

The invention relates to a detection technology of soil-water characteristics of unsaturated soil, in particular to a sensor for rapid quantitative detection of soil-water characteristics of unsaturated soil and an application thereof.

technical background

Most of the soil encountered in the process of large-scale engineering construction is in an unsaturated state. Unsaturated soil is a solid-liquid-gas three-phase composite medium, and its engineering properties are very complex. In recent years, the theory of unsaturated soil mechanics has been widely used in the evaluation of slope stability and the prediction of rainfall landslides, and the soil-water characteristic curve plays an important role in unsaturated soil mechanics. (1) The soil-water characteristic curve The unsaturated soil permeability coefficient can be calculated by combining the curve with the horizontal soil column permeability test data; (2) The mathematical model of the soil-water characteristic curve is one of the constitutive relations of the unsaturated soil; (3) The soil-water characteristic curve can be Estimate the strength, deformation and hydraulic coefficient of the excavated soil. Therefore, the soil-water characteristic curve (SWCC) has attracted the attention of many scholars as the basic test content of unsaturated soil theory research. Some scholars have developed and used suction sensors that can measure high suction values. Although the principles of these sensors are similar, when the sensors themselves are different, the test methods used are also different, which need to be designed according to the actual test conditions. At present, there are two main methods for analyzing the suction of unsaturated soils: direct method and indirect method. For moisture content observation, commonly used methods include in-situ testing—that is, direct measurement by in-situ sampling, volumetric moisture content probe measurement, and other indirect measurement methods, such as neutron moisture meter, gamma ray measurement, etc.

Above-mentioned method, all there is the unsatisfactory place in engineering use. Such as the hygrometer method in the direct measurement technology, the disadvantages are: the calibration and measurement equipment are more complicated, the environmental requirements are high, and it cannot be used for on-site measurement; the suction value below 100kPa cannot be measured; the thermocouple is in an acidic environment. It is easy to corrode, and after each calibration or use, it must be measured and cleaned according to the manufacturer's instructions; it is difficult to analyze the results measured with a dirty or unqualified hygrometer. The same tensiometer method also has disadvantages, such as: (1) High requirements for use: once air appears in the measurement system, the pore water pressure measurement of the closed system will be wrong, so it is very important to ensure that there is no air in the tensiometer tube. Before use, it is necessary to ensure that the ceramic head is not blocked and cracked, and then remove the air in the tensiometer as much as possible, and saturate the ceramic head and plastic tube of the tensiometer with water that removes air. Pressure gauge readings recorded at the surface must be head corrected for the height of the water column in the tensiometer tube. (2) Limitations of use: a. The ceramic head of the tensiometer must be in good contact with the soil to ensure that the water in the soil is continuous with the water in the tensiometer tube, but this is not easy to determine (especially in the field). b. The ceramic head is fragile and easy to crack, and once cracked, it cannot be used again. c. The measurement range will be limited by the "cavitation" phenomenon: when the pore water pressure is close to minus one atmospheric pressure, the water will be vaporized, which will cause air in the measurement system and cannot be read correctly. It can be seen that the absolute value of the negative pore water pressure measured by the tensiometer will not exceed one standard atmospheric pressure. d. The measurement range will also be limited by the air intake value of the ceramic head: to ensure that the air intake value of the ceramic head must be greater than the suction force of the substrate to be measured, otherwise the air will pass through the ceramic plate and enter the measurement system. The disadvantages of the pressure plate instrument are: a. When using the axial translation technology for long-term tests, it is difficult to ensure that there are no air bubbles in the water pressure measurement system: because the permeability coefficient of the soil sample and the ceramic plate with high air intake value are low, the balance The time tends to be longer. Pore air may diffuse through the water in the high air intake value ceramic plate during this period and appear as bubbles under the ceramic plate, making the measured matrix suction low. b. The air intake value of the ceramic plate is inversely proportional to the maximum pore diameter of the plate, while the permeability coefficient becomes larger with the increase of the plate pore diameter. There is a strong contradiction between the air intake value and the permeability coefficient of the ceramic plate.

For the heat conduction sensor method in the indirect measurement technology, its disadvantages are: a. There are special requirements for the manufacture and use of the ceramic head of the heat conduction sensor. b. Thermal diffusion causes the probe to have a temperature gradient along the radial direction, resulting in temperature stress, and long-term use is prone to cracks; because the permeability coefficient of the soil decreases with the decrease of water content, the balance time of the sensor is longer when measuring the high suction force; it cannot be continuous 1. Real-time measurement: After the data is collected once, the next measurement operation can only be performed after the temperature rise in the middle of the probe returns to zero, otherwise the basic conditions of each thermal diffusion are different. The disadvantages of the filter paper method are: a. When using it, it is necessary to distinguish the difference between the non-contact filter paper method and the contact filter paper method. The former is suitable for measuring high suction values > 100kPa, and the latter is more suitable for measuring low suction. In addition, it is likely that total suction is measured rather than matrix suction. In addition, the filter paper must be dust-free quantitative analysis type II filter paper (conforming to ASTME832 standard), which is very demanding. b. When measuring the equilibrium water content, high-precision balances and ovens with an accuracy of 0.0001 grams are required, so it must be carried out in the laboratory with undisturbed or disturbed soil samples taken from the field. c. The application has obvious limitations and is difficult to automate. At present, it is manual operation, especially in the data acquisition stage, which requires high manual technology. The results are greatly affected by the operator and laboratory conditions, and the accuracy is difficult to guarantee; the balance time is long. , The equilibrium time generally takes 7~10 days; if the initial wet filter paper is used, it usually takes 21~25 days. d. The water storage characteristics of the filter paper material may affect the high suction range. For the contact filter paper method, it is difficult to ensure good contact between the filter paper and the soil sample.

In addition to the above methods, some scholars also use time-domain reflectometry (TDR). In this technical method, the dielectric constant of soil not only changes with the water content of the soil, but also is affected by the density, temperature, salinity, mineral composition, etc. of the soil. Among them, the particle size and bulk density of the soil have the greatest influence on the calibration curve. In addition, the capacitive suction meter is suitable for measuring the suction below 200kPa, but the influence of the electrolyte dissolved in water on the output value of the sensor needs to be considered.

As the foundation construction of large-scale projects and the prevention and treatment of side slopes and landslides are paid more and more attention, it is hoped that a simple and easy-to-use detection device can be studied as soon as possible. This device should be able to quickly and accurately grasp the unsaturated soil Soil and water characteristics to meet indoor and field engineering use.

Contents of the invention

An object of the present invention is to provide a sensor for rapid quantitative detection of soil water characteristics of unsaturated soil.

The sensor for rapid quantitative detection of soil water characteristics of unsaturated soil of the present invention includes coupling coils, ACVG, IA, acv/dcv, VA, AC/DC, CV for detecting the water content of soil samples;

Each group of coupling coils is a combination of two coils L1 and L2 nested together to form mutual coupling, and the coil L1 is the excitation coil that generates the main magnetic field, and the coil L2 is the feedback coil that extracts the change of the microelectronic current ;

The IA connection coil L1 in the module composed of ACVG and IA constitutes an alternating current with a frequency of 100MHz, an intensity of 1 to 10 microtesla, and a stability of ±0.5 microtesla to generate a microelectronic flow when the object under test is excited. magnetic field circuit;

The VA connection coil L2 in the module composed of acv/dcv plus VA constitutes a detection circuit for detecting changes in the microelectronic flow generated by the excitation of the object to be tested;

One end of the fully sealed and waterproof casing is provided with a coupling coil, and the other end is provided with a junction box including a power input terminal and a detection signal output terminal; the AC/DC conversion circuit and the subsequent CV are arranged in the casing, and the module composed of ACVG and IA is connected by acv A module composed of /dcv plus VA; acv/dcv is connected to the output terminal of the detection signal;

Among them, AC/DC: ~220V-50Hz AC to DC power supply circuit;

CV: constant voltage 12V circuit;

ACVG: high frequency voltage signal generator circuit;

IA: high frequency current constant current circuit;

VA: microelectronic current voltage amplifier circuit;

acv/dcv: High-frequency signal voltage to DC signal voltage circuit.

The indoor sensor used indoors is square or circular, and the coupling coil is hollow. The field sensor used in the field is circular, and the coupling coil is fully enclosed.

In order to compare dry soil and wet soil, two identical coupling coils are set in the indoor sensor used indoors. One is used to detect the inherent residual water content of the dry soil sample submitted for inspection, and the other is used to detect the change in water content of the soil sample submitted for inspection.

For the convenience of electricity use, the sensor power input terminal is provided with ~220V-50Hz interface and +12V interface; the ~220V-50Hz interface is connected to the AC/DC conversion circuit in the shell and the subsequent constant voltage 12V circuit CV.

In the sensor of the present invention, its coil is a helicoidal coil wound on a hollow frame, and after forming, its outer diameter is 12 mm, its inner diameter is 5 mm, its length is 10 mm, and its inductance is 0.5 nH to 100 μH. The material of the hollow frame is non-conductive non-conductive The metal tube is selected from quartz glass tubes, ceramic tubes and polytetrafluoroethylene plastic tubes.

Another object of the present invention is to provide an application method of a sensor for rapid quantitative detection of soil water characteristics of unsaturated soil.

The method is divided into indoor detection and field detection.

The main steps of indoor testing include:

1) Prepare the sample to be tested;

2) For the indoor sensor used, the operating power supply voltage of the experimental device is 12VDC, and the initial value of the excitation magnetic field frequency of the charge dipole polarization in the sample to be tested is set to 100MHz;

3) Load two identical samples into two coils respectively;

4) Inject pure water into the sample to be tested in one of the coupling coils, and do not add pure water to the sample in the other coupling coil;

5) Record the water content change value until the water content of the tested sample is saturated and reaches equilibrium, that is, the recorded voltage value remains unchanged;

6) According to the voltage value measured by the type of soil, the moisture content of the soil is obtained from the pre-drawn reference standard for the calibration of the relationship between voltage value and moisture content;

The main steps of field detection include:

1) Drilling holes in the soil slope;

2) Embed the field sensor in the hole, with the coupling coil facing down, close to the soil layer, and then fill the hole with soil and compact it;

3) Simulate artificial rainfall and water the soil slope where the sensor is buried;

4) Record the change value of water content until the water content of the tested sample is saturated and reaches equilibrium, that is, the recorded voltage value remains unchanged;

5) According to the measured voltage value of the soil type, the moisture content of the soil is obtained from the pre-drawn calibration reference standard of the voltage value-moisture content relationship.

Indoor detection step 1) First, put the silt that has passed through a 2mm sieve into the coupling coil, and then compact it into a dense shape. Its geometric dimensions are cylinders with a diameter of 5 mm and a height of 10 mm. In the specific implementation process, step 1) and step 3) can also be combined, and the sample to be tested can be directly loaded into the coupling coil in powder form, compacted, and a certain height of the soil column can be guaranteed, which can save trouble and can Avoid the situation that the prefabricated test sample cannot be put into the coupling coil due to the size change.

Indoor detection step 5) Record the change value of water content every minute.

In the field detection step 1), the size of the drilling hole is at least equal to the outer diameter of the field sensor, and the depth is at least equal to the length of the field sensor.

In the field detection step 4) record the change value of water content every minute.

According to the principle that different minerals in unsaturated soil produce micro-electron flow effect under the action of AC electromagnetic field, the unsaturated soil is placed in the AC electromagnetic field, and the change of micro-electron flow is detected, so as to obtain the soil water content in unsaturated soil and properties of soil.

The invented and designed rapid quantitative detection method of unsaturated soil-water characteristics is that the unsaturated soil is sieved into the coupling coil and compacted to form a cylinder; a 100MHz AC current is connected to the coupling coil to generate a high stability , micro-extra-level AC magnetic field, and then activate the charged particles of soil water in the unsaturated soil to polarize it, thus forming a microelectronic current. It is found through experiments that the magnitude of the microelectronic current intensity is related to the properties and water content of the unsaturated soil, and the microelectronic current is converted into a DC voltage signal through a high-sensitivity detection sensor. Finally, the soil water content in the tested sample is obtained according to the output voltage variation.

The IA connection coil L1 in the module composed of ACVG and IA constitutes an AC magnetic field circuit, which is used to generate high frequency, high Stability and micro-level AC magnetic field activates the charged particles of soil water in unsaturated soil to polarize them to form microelectronic current.

The VA connection coil L2 in the module composed of acv/dcv plus VA constitutes a detection circuit for detecting changes in the microelectronic flow generated by the excitation of the object to be tested, and is used to convert the microelectronic current into a DC voltage signal and detect it.

Make cylinders of silt and clay that are important to be tested as samples in turn, and obtain the analog voltage value output by the sensor under the action of the AC magnetic field for unsaturated soil with a certain moisture content, that is, the calibration reference standard for a certain unsaturated soil;

Compare the voltage value of the sample to be tested with the voltage of the standard sample, and obtain its content according to the corresponding analog voltage increment;

The soil water content of various unsaturated soils is proportional to the influence of the sensor output voltage increment. If the voltage increment of the soil water content of an unsaturated soil is obtained, the corresponding voltage increment can be identified. The soil water content of the unsaturated soil.

The sensor for rapid quantitative detection of unsaturated soil and water characteristics of the present invention has the physical quantity that can convert electrons carried by substances such as soil and water into microelectronic currents, and then reflect the soil and water of unsaturated soil samples to be tested according to the strength of the physical quantity of electricity Characteristics change law and quick test of soil water content. It can be used for real-time observation indoors and outdoors.

The advantages of the present invention are: 1) No need for sample pretreatment, direct sample injection and detection, short detection time; 2) The output of the sensor is a DC voltage signal, with high sensitivity, small error, good linearity and repeatability, and the experiment Proved detection reproducibility: ±1.5%, relative error: ±1.5%. 3), can be directly connected with monitoring equipment, easy to realize high-speed online real-time monitoring and control; 4), strong anti-interference ability, can work normally in harsh environments; 5), the sensor is small in size, easy to install and debug, simple to operate, High cost performance.

Description of drawings

Fig. 1 is the structure schematic diagram of fast quantitative detection sensor of unsaturated soil water characteristic of the present invention; Wherein a is the exterior structure of indoor sensor; b is the internal structure of a; c is the external structure of field sensor; d is the internal structure of c; The marks are expressed as: 1-indoor coupling coil, 2-outdoor coupling coil, 3-power input and detection signal output junction box, 4-housing; 5-module composed of ACVG plus IA, 6-acv/dcv plus Modules composed of VA;

Fig. 2 is a general diagram of the electrical principle of the sensor of the present invention;

Fig. 3 The relationship of moisture content in samples 4 ^# and 5 ^# of Yellow River silt (0.6g) with time;

Fig. 4 The relationship of moisture content in the Yellow River silt (0.3g) A ^# , B ^# samples with time;

Figure 5 shows the linearity and repeatability of the sensor for different unsaturated soil water detection;

Figure 6 shows the results of field experiments on silty clay in the North Sea.

detailed description

Example 1

indoor sensor

See Figure 1a and Figure 1b. Two identical coupling coils 1 are arranged at one end of the completely sealed and waterproof casing 4, and a junction box 3 including a power supply input end and a detection signal output end is arranged at the other end; an AC/DC conversion circuit and a subsequent CV are arranged in the casing (see Figure 2), module 5 composed of ACVG plus IA is connected to module 6 composed of acv/dcv plus VA; acv/dcv is connected to the detection signal output. IA is connected to coil L1 in the module composed of ACVG plus IA, and VA is connected to coil L2 in the module composed of acv/dcv plus VA. Coupling coil 1 is a combination of two coils L1 and L2 nested together to form a mutual coupling effect, and coil L1 is an excitation coil for generating a main magnetic field, and coil L2 is a feedback coil for extracting microelectronic current changes.

See Figure 2.

AC/DC:~220V-50Hz AC to DC power supply circuit;

CV: high stability, low temperature wave coefficient, constant voltage 12v circuit;

ACVG: high frequency voltage signal generator circuit;

IA: high frequency current constant current circuit;

VA: voltage amplifier circuit;

acv/dcv: High-frequency signal voltage to DC signal voltage circuit.

The sensor is square, and the coupling coil 1 is hollow.

The sensor power input terminal is provided with a ~220V-50Hz interface and a +12V interface; the ~220V-50Hz interface is connected to the AC/DC conversion circuit in the shell 4 and the subsequent constant voltage 12v circuit CV.

Coil L1 and coil L2 are nested together, which is a spiral tube coil wound on an air-core skeleton, with an outer diameter of 12mm, an inner diameter of 5mm, a length of 10mm, and an inductance of 0.5nH to 100μH. The material of the hollow skeleton is polytetrafluoroethylene Vinyl tubing.

Example 2

Outdoor Sensor

See Figure 1c and Figure 1d. The sensor is circular, and a coupling coil 2 is arranged at one end of a completely sealed and waterproof casing 4, and the coupling coil is fully enclosed. The material of the hollow core frame wound with the coil is a ceramic tube.

All the other are identical with embodiment 1.

Application Example 1

Indoor testing

This example is for the detection of the soil and water characteristics of the Yellow River silt and Guilin red clay. The main steps are as follows:

1 Experimental materials

The soil used in the test was silt from the Yellow River Delta and red clay from Yanshan Mountain in Guilin City. The remolded soil sample was passed through a 2mm sieve, and the specific gravity of the silt in the Yellow River Delta was measured to be 2.71; the liquid limit was 22.6, and the plastic limit was 14.6 . The specific gravity of Yanshan red clay in Guilin City is 2.72; the liquid limit is 47.4, and the plastic limit is 26.7.

2 Sample preparation

Sample preparation steps: Put the silt that has passed through a 2mm sieve into the coupling coil, and compact it with a metal rod to form a dense shape. Its geometric dimensions are 5mm in diameter and 20mm in height; and 5mm in diameter and 12m in height.

3 Experimental methods

3.1 Experimental conditions

In order to examine the feasibility of this method, the weight and total water absorption of the sample to be tested are known. There are two types of specifications, as mentioned earlier. The operating power supply voltage of the experimental device is 12VDC, and the initial value of the excitation magnetic field frequency of the charge dipole polarization in the sample to be tested is set to 100MHz.

3.2 Experimental steps

1) Inject 0.30g of the Yellow River silt sample (a cylinder with a diameter of 5mm and a height of 12m) into 0.15ml of pure water, and record the change in water content every minute until the water content of the tested sample is saturated and reaches equilibrium.

2) Inject 0.30g of the Yellow River silt sample (a cylinder with a diameter of 5mm and a height of 12m) into 0.10ml of pure water, and record the change in water content every minute until the water content of the tested sample reaches equilibrium. Then add 0.02ml of pure water, continue to observe the change value of the water content, and record the data every minute until the water content of the tested sample reaches equilibrium.

3) Inject 0.30g of Guilin red clay sample (5mm in diameter and 12m in height) into 0.15ml of pure water, and record the water content change value every minute until the water content of the tested sample is saturated and reaches equilibrium.

4) Inject 0.30g of Guilin red clay sample (5mm in diameter and 12m in height) into 0.10ml of pure water, and record the change of water content every minute until the water content of the tested sample reaches equilibrium. Then add 0.10ml of pure water, continue to observe the change of water content, and record the data every minute until the water content of the tested sample reaches equilibrium.

5) Inject 0.60g of the dense Yellow River silt sample (5mm in diameter and 22mm in height) into 0.30ml of pure water, and record the change in water content every minute until the water content of the tested sample is saturated and reaches equilibrium.

6) Inject 0.60g of non-compact Yellow River silt sample (5mm in diameter and 22mm in height) into 0.30ml of pure water, and record the water content change value every minute until the water content of the tested sample is saturated and reaches equilibrium.

4. Experimental results

4.1 Comparison of water absorption of Yellow River silt samples

Yellow River silt (0.6g) 4 ^# , 5 ^# , after being pressurized and compacted, 0.30ml of pure water was injected, and then the soil-water characteristic curve of the data was collected every 5 minutes, as shown in Figure 3. After samples 4 ^# and 5 ^# were injected with 0.30ml of pure water at time t ₀ , the sensor reflected that the moisture in the soil increased rapidly, and had entered a saturated state at time t ₁₅ . Because residual water appeared above the sample and remained unchanged after several minutes, this indicated that the water content in the soil was saturated.

Yellow River silt (0.3g) A ^# is slightly compacted, and the soil-water characteristic curve of injecting 0.15ml of pure water is shown in Figure 4. It can be seen from Figure 4 that when 0.15ml of pure water is injected at t ₀ , the sensor reflects that the water in the soil increases rapidly, and it has entered a saturated state at t ₄ . Because there is residual water above the sample, which remains unchanged after several minutes, this indicates that the water content in the soil is saturated.

The soil-water characteristic curve of Yellow River powder soil (0.3g) B ^# , after being slightly compacted, was injected with 0.10ml and 0.02ml of pure water in two stages, as shown in Figure 4. After injecting _0.10ml of pure water at time _t0 , the sensor reflected that the moisture in the soil increased rapidly, and it seemed to be saturated at time t4. In order to confirm whether it is correct or not, inject 0.02ml of pure water at t ₂₅ . The sensor reflects that the water content in the soil continues to rise, but it begins to drop slightly until it reaches equilibrium at time _t34 , and there is remaining water above the sample, which indicates that the water content in the soil is saturated.

It can be seen from Figure 3 and Figure 4 that after the water content in the soil reaches saturation, and then inject water into the sample, the sensitive value of the sensor no longer changes with the increase of water.

4.2 Sensor performance comparison

In summary, the curve A ^# in Fig. 4 is that the weight of the tested sample is 0.3g, and the volume is After applying 0.15ml of pure water to the Yellow River silt, as time goes by, the results of water absorption changes are recorded every minute. Curve B# is the weight of the tested sample is 0.3g, the volume is After the Yellow River silt was applied with different milliliters of pure water at different times, the results of water absorption changes were recorded every minute as time went by. Among them, from time t ₀ to time t ₂₅ is the change curve of applying 0.1ml of pure water, and from t ₂₅ - to t ₃₅ is the change curve of adding 0.02ml of pure water.

From the time _t3 to _t25 of the A ^# curve, the water content fluctuates obviously up and down, and the water content of the B ^# curve also fluctuates obviously up and down from the time _t3 to _t15 . This shows that the soil water content is unstable until it reaches saturation, which also reflects the difference in suction. From another point of view, these two curves also reflect that when the water content in the soil is saturated, they are coincident. This shows that the water content sensed by the sensor is very repeatable. It can also be seen from their linearity curves (Figure 5) that their linearity is very good and the error is very small.

Application Example 2

Field detection

This example is aimed at the detection of soil water characteristics of silty clay in the North Sea. The main steps are as follows:

1. The embedding point is selected on an artificial soil slope with a vertical height of 2 meters and a slope of about 35 degrees, which is silty clay;

2. Drilling, with a diameter of 0.050 meters and a depth of 0.30 meters, the hole is perpendicular to the slope, and the vertical height from the ground level is 0.5 meters;

3. Bury the sensor with the end of the coupling coil facing down, backfill the removed soil into the hole and compact it, and then open a 0.1-meter-wide and 0.05-meter-deep groove at 0.1 meters below the hole;

4. Power on the sensor and preheat for 2 minutes;

5. Simulate artificial rainfall, water the soil slope, and observe the change of water content in the soil;

6. Record data, record the output voltage value of the sensor every 1 minute, until the output voltage value of the sensor remains unchanged, stop watering, and the experiment ends.

It can be seen from Figure 6 that the output voltage value of the sensor has a good linear relationship with the water content in the soil, and the linearity is very good in the range of 10-60% water content, and the error is very small.

Claims (8)

1. unsaturated soil soil water characteristic Quantitative detection sensor, is characterized in that: comprise the pickup coil for detecting soil sample water cut, ACVG, IA, acv/dcv, VA, AC/DC, CV;

Often organize pickup coil to be combined by two coil L1 forming mutual coupling effect nested together and coil L2, and its coil L1 is the magnetizing coil producing main field, coil L2 is the tickler extracting the change of microelectronics stream;

ACVG adds the IA connecting coil L1 in the module of IA composition, forms the AC magnetic field circuit making determinand excited target produce microelectronics stream; Its frequency is 100MHz, intensity is 1 ~ 10 micro-tesla;

Acv/dcv adds the VA connecting coil L2 in the module of VA composition, forms the testing circuit detecting the microelectronics stream change that determinand excited target produces;

One end of the shell of complete water-tight arranges described pickup coil, and the other end arranges the terminal box comprising power input and detection signal output terminal; AC/DC change-over circuit and subsequent CV are set in shell, are added module that IA forms and acv/dcv by ACVG and add the module that VA forms; Add by ACVG model calling that IA forms and add by acv/dcv the module that VA forms; Acv/dcv connects detection signal output terminal; Power input setting ~ 220V-50Hz interface and+12V interface; AC/DC change-over circuit in ~ 220V-50Hz interface connected with outer casing and subsequent CV;

Wherein, AC/DC: ~ 220V-50Hz AC/DC power circuit;

CV: constant voltage 12v circuit;

ACVG: high-frequency voltage signal generator circuit;

IA: high-frequency current constant-current circuit;

VA: microelectronics stream voltage amplifier circuit;

Acv/dcv: high-frequency signal voltage turns direct-flow signal voltage circuit.

2. sensor according to claim 1, is characterized in that: be square or circular at the indoor type sensor of indoor use, and pickup coil is hollow, and the outdoor type sensor used in the wild is circle, and pickup coil is totally enclosed.

3. sensor according to claim 2, is characterized in that: at indoor type sensor setting two duplicate pickup coils of indoor use.

4. the application process of sensor in unsaturated soil soil water characteristic Quantitative detection of claim 2, is characterized in that: be divided into indoor detection and field to detect,

Indoor detection key step comprises:

1) tested sample is prepared;

2) the indoor type sensor used, the working power voltage of experimental provision is 12VDC, makes the charge dipole muon polarization excitation field initial frequency in tested sample be set as 100MHz;

3) two same are respectively charged in two pickup coils by test agent;

4) injected pure water to one of them pickup coil by test agent, the sample in another pickup coil does not add pure water;

5) change of moisture content value is recorded, until reached balance, till the magnitude of voltage namely recorded is constant by the water cut of test agent is saturated;

6) measure magnitude of voltage according to the type of soil, obtain this soil's water content from the calibration normative reference of pre-rendered magnitude of voltage ~ water percentage relation;

Field is detected key step and is comprised:

1) hole at slight slope;

2) outdoor type sensor is imbedded in hole, soil layer, is close to down in pickup coil one end, then with soil, compacting is filled up in hole;

3) simulate rainmaking, water to the slight slope burying sensor underground;

4) change of moisture content value is recorded, until reached balance, till the magnitude of voltage namely recorded is constant by the water cut of test agent is saturated;

5) measure magnitude of voltage according to the type of soil, obtain this soil's water content from the calibration normative reference of pre-rendered magnitude of voltage ~ water percentage relation.

5. method according to claim 4, is characterized in that: indoor detecting step 1) be that the silt crossing 2mm sieve loads in container, hit real compact formed for physical dimension be the right cylinder of diameter 5mm, high 10mm ~ 22mm; Or step 1) and step 3) are merged, directly will be loaded in pickup coil with powdery by test agent, and hit reality.

6. method according to claim 5, is characterized in that: at indoor detecting step 5) each a minute record change of moisture content value.

7. method according to claim 5, is characterized in that: detecting step 1 in the wild), bore size is that diameter at least equals outdoor type sensor external diameter, the degree of depth at least equals outdoor type sensor length.

8. method according to claim 5, is characterized in that: detecting step 4 in the wild) each a minute record change of moisture content value.