CN116359277A - Method for in-situ monitoring of volume weight of non-rigid soil - Google Patents
Method for in-situ monitoring of volume weight of non-rigid soil Download PDFInfo
- Publication number
- CN116359277A CN116359277A CN202310086020.4A CN202310086020A CN116359277A CN 116359277 A CN116359277 A CN 116359277A CN 202310086020 A CN202310086020 A CN 202310086020A CN 116359277 A CN116359277 A CN 116359277A
- Authority
- CN
- China
- Prior art keywords
- soil
- probe
- rigid
- heat pulse
- target non
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 239000002689 soil Substances 0.000 title claims abstract description 303
- 238000000034 method Methods 0.000 title claims abstract description 39
- 238000012544 monitoring process Methods 0.000 title claims abstract description 34
- 238000011065 in-situ storage Methods 0.000 title claims abstract description 23
- 239000000523 sample Substances 0.000 claims abstract description 171
- 239000004519 grease Substances 0.000 claims abstract description 12
- 229920001296 polysiloxane Polymers 0.000 claims abstract description 12
- 238000013213 extrapolation Methods 0.000 claims abstract description 6
- 238000010438 heat treatment Methods 0.000 claims description 49
- 238000001514 detection method Methods 0.000 claims description 21
- 239000004576 sand Substances 0.000 claims description 12
- 239000004927 clay Substances 0.000 claims description 9
- 239000011888 foil Substances 0.000 claims description 9
- 230000008859 change Effects 0.000 claims description 8
- 230000035945 sensitivity Effects 0.000 claims description 8
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 8
- 229920001817 Agar Polymers 0.000 claims description 6
- 238000001035 drying Methods 0.000 claims description 5
- 238000004364 calculation method Methods 0.000 claims description 4
- 238000005520 cutting process Methods 0.000 claims description 4
- 238000012937 correction Methods 0.000 claims description 3
- 230000004044 response Effects 0.000 claims description 3
- 238000013461 design Methods 0.000 abstract description 17
- 238000005516 engineering process Methods 0.000 abstract description 7
- 230000008569 process Effects 0.000 abstract description 7
- 230000007774 longterm Effects 0.000 abstract description 4
- 230000008602 contraction Effects 0.000 abstract description 3
- 238000005336 cracking Methods 0.000 abstract description 3
- 230000007547 defect Effects 0.000 abstract description 3
- 238000005259 measurement Methods 0.000 description 5
- 230000001276 controlling effect Effects 0.000 description 2
- 230000005284 excitation Effects 0.000 description 2
- 230000006698 induction Effects 0.000 description 2
- 230000009471 action Effects 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 239000002734 clay mineral Substances 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 238000005429 filling process Methods 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 230000000704 physical effect Effects 0.000 description 1
- 230000005855 radiation Effects 0.000 description 1
- 238000002310 reflectometry Methods 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 238000005070 sampling Methods 0.000 description 1
- 230000008961 swelling Effects 0.000 description 1
- 230000001360 synchronised effect Effects 0.000 description 1
- 238000012795 verification Methods 0.000 description 1
Images
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N25/00—Investigating or analyzing materials by the use of thermal means
- G01N25/20—Investigating or analyzing materials by the use of thermal means by investigating the development of heat, i.e. calorimetry, e.g. by measuring specific heat, by measuring thermal conductivity
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/02—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance
- G01N27/22—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating capacitance
- G01N27/221—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating capacitance by investigating the dielectric properties
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/02—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance
- G01N27/22—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating capacitance
- G01N27/223—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating capacitance for determining moisture content, e.g. humidity
Landscapes
- Chemical & Material Sciences (AREA)
- General Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Health & Medical Sciences (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- Investigating Or Analyzing Materials Using Thermal Means (AREA)
Abstract
The invention relates to a method for in-situ monitoring of the volume weight of non-rigid soil, which aims at the problems of increased contact thermal resistance, field temperature drift and the like generated in the expansion and contraction process of the non-rigid soil, adopts brand new design, and on the principle of a thermal pulse-time domain reflection technology, utilizes a soil thermal pulse probe and a soil moisture probe to fill up the technical blank of long-term in-situ monitoring of the volume weight dynamics of the soil by a plurality of probes, determines the volume weight value of the non-rigid soil according to a design model based on the acquisition of the soil thermal conductivity value and the soil volume moisture content value, and adopts high-thermal conductivity silicone grease to improve the thermal contact between the soil thermal pulse probe and the soil aiming at the soil thermal pulse probe, thereby overcoming the defect of increased volume weight prediction error caused by the cracking of the non-rigid soil in the traditional method; the volume weight prediction deviation under different weather conditions caused by ambient temperature drift during field monitoring is corrected by a linear extrapolation method; the method is improved and optimized, is easy to operate and implement under field conditions, improves the accuracy of in-situ monitoring of the volume weight of the non-rigid soil, and has popularization significance.
Description
Technical Field
The invention relates to a method for in-situ monitoring of the volume weight of non-rigid soil, and belongs to the technical field of soil physical property measurement.
Background
The soil volume weight is one of the most common indexes for representing the soil structure, and plays an important role in regulating and controlling the water and gas transmission of the soil and the growth process of crops. At present, the dynamic change of the volume weight of the obtained soil is mainly carried out by a field interval sampling method, which is time-consuming and labor-consuming, and a continuous dynamic process of the soil structure cannot be obtained.
The thermal pulse-time domain reflectometry (Thermo-TDR) technology can utilize the synchronously acquired soil thermal characteristics and water content to reversely calculate the soil volume weight, so that the continuous monitoring of the soil volume weight is realized. However, at present, the heat pulse-time domain reflection technology is not commercially applied, but the manufacturing process of the self-made probe is complex, and some uncertainty differences exist between the probes, so that the wide application of the technology is limited. The method has the advantages that the method combines the marketized soil moisture and heat pulse probes, realizes accurate volume weight measurement in different rigid soil types, and further improves the application prospect of the technology.
However, for non-rigid soils rich in swelling clay minerals, the severe shrinkage of the soil not only causes significant deformation of the probe itself, but also the soil fissures develop gradually during water loss. The air gap formed between the probe and the soil remarkably increases the contact thermal resistance of the soil, so that a larger error is generated in the volume weight prediction. In the field monitoring process, the volume weight prediction has more uncertainty, for example, besides the pulse heating process, the measurement of the thermal characteristics of the field soil is more susceptible to the influence of solar radiation and ambient temperature drift, so that larger deviation of the volume weight prediction between day and night or under different weather conditions is caused. Therefore, there is a need to develop an in-situ monitoring method for the non-rigid soil volume weight, which is accurate, convenient and easy to popularize, and fills the technical blank of monitoring the soil volume weight dynamic by combining multiple probes.
Disclosure of Invention
The invention aims to solve the technical problems of increased contact thermal resistance, field temperature drift and the like in a non-rigid soil expansion process, and provides a method for in-situ monitoring of the volume weight of non-rigid soil.
The invention adopts the following technical scheme for solving the technical problems: the invention designs a method for in-situ monitoring of the volume weight of non-rigid soil, which is based on the simultaneous detection of the thermal conductivity and the volume water content of target non-rigid soil by a soil heat pulse probe and a soil moisture probe, and comprises the following steps of A to C, so as to realize the soil volume weight value rho of the target non-rigid soil b Is detected;
step A. Based on the probe sensitivity S of the soil heat pulse probe, the length L of the heating wire in the soil heat pulse probe, the resistance R of the heating wire in the soil heat pulse probe, and the voltage U at two ends of the heating wire in the soil heat pulse probe heater The output voltage U of the probe before and after the heating of the soil heat pulse probe corresponding to the preset heating time of the probe 0 And U 1 Obtaining a soil heat conductivity value lambda of target non-rigid soil, and then entering a step B;
step B, obtaining the soil volume moisture value theta of the target non-rigid soil according to the soil dielectric constant Eb of the target non-rigid soil obtained by the soil moisture probe v Then enter step C;
step C, according to the soil thermal conductivity value lambda and soil volume moisture content value theta of the target non-rigid soil v For the following model:
iterative calculation to obtain soil total porosity phi of target non-rigid soil and soil of target non-rigid soilVolume weight value ρ b Wherein α=0.67 f clay +0.24，β＝1.97f sand +1.87ρ b -1.36f sand ρ b -0.95，f sand And f clay Respectively representing sand grain and clay grain content, lambda of target non-rigid soil dry Indicating the dry soil thermal conductivity.
As a preferred technical scheme of the invention: in the step A, the probe sensitivity S based on the soil heat pulse probe, the length L of the heating wire in the soil heat pulse probe, the resistance R of the heating wire in the soil heat pulse probe and the voltage U at two ends of the heating wire in the soil heat pulse probe are adopted heater The output voltage U of the probe before and after the heating of the soil heat pulse probe corresponding to the preset heating time of the probe 0 And U 1 The following formula is adopted:
obtaining a soil thermal conductivity value lambda of the target non-rigid soil, wherein S represents the probe sensitivity of the soil heat pulse probe, Q represents the electric power of each meter of heating wire in the soil heat pulse probe, and DeltaU represents U 1 And U 0 The difference between them, and then step B is entered.
As a preferred technical scheme of the invention: in the step B, according to the soil dielectric constant Eb of the target non-rigid soil obtained by the soil moisture probe, the following formula is adopted:
θ v ＝4.3×10 -6 ×Eb 3 -5.5×10 -4 ×Eb 2 +2.92×10 -2 ×Eb-5.3×10 -2
obtaining the soil volume moisture value theta of the target non-rigid soil v Then step C is entered.
As a preferred technical scheme of the invention: and (C) detecting the target non-rigid soil by the soil heat pulse probe in the step A, removing detection data of a preset daytime period, and executing the step A according to the detection data of the preset nighttime period to obtain a soil heat conductivity value lambda of the target non-rigid soil.
As a preferred technical scheme of the invention: in the step A, with respect to the detection of the target non-rigid soil by the soil heat pulse probe, for detection data of a preset night time period, the following linear extrapolation formula is adopted:
U 0 (t)＝at+b
fitting to obtain a trend equation U of the output voltage of the soil heat pulse probe corresponding to the probe before heating along with the change of time (t) 0 (t) correcting the influence of the ambient background temperature on the detection data in the monitoring process of the preset night time period, and applying U according to at 1 Result update U of-at 1 Updating and obtaining the output voltage U of the correction probe after the soil heat pulse probe is heated corresponding to the preset probe heating time length 1 Wherein a, b represent equation fitting parameters.
As a preferred technical scheme of the invention: before the soil moisture probe detects the target non-rigid soil, the soil moisture probe and the drying method are respectively applied to obtain the measured value of the soil cutting ring sample, and the linear relation between the measured value and the soil cutting ring sample is obtained for subsequently correcting the error of the soil moisture probe on the target non-rigid soil detection.
As a preferred technical scheme of the invention: in the step a, based on the obtaining of the soil thermal conductivity value λ of the target non-rigid soil, the method further comprises the following steps of k=k reference ×T reference Obtaining the soil thermal diffusivity K of the target non-rigid soil, and further obtaining the soil volumetric heat capacity C of the target non-rigid soil according to C=lambda/K; wherein K is reference Shows the thermal diffusivity of the standard reference agar gel at 20 ℃, T reference Represents the time period required for the output voltage to drop to 37% of DeltaU after heating of a standard reference agar gel at 20 ℃, deltaU representing U 1 And U 0 And the difference value T represents the response time length of the probe output voltage reduced to 37% of DeltaU after the soil heat pulse probe is heated corresponding to the preset probe heating time length.
As a preferred technical scheme of the invention: before the soil heat pulse probe is used for detecting the target non-rigid soil, the high heat conduction silicone grease is smeared on the surface of the soil heat pulse probe foil, and the smearing thickness of the high heat conduction silicone grease is not more than 1mm because the heat pulse probe accurately measures the influence (radius is 4 mm) of the space range of the soil heat characteristic.
Compared with the prior art, the method for in-situ monitoring of the volume weight of the non-rigid soil has the following technical effects:
(1) The invention designs a method for in-situ monitoring of the volume weight of non-rigid soil, which aims at the problems of increased contact thermal resistance, field temperature drift and the like generated in the expansion and contraction process of the non-rigid soil, adopts brand new design, and on the principle of a thermal pulse-time domain reflection technology, utilizes a soil thermal pulse probe and a soil moisture probe to fill up the technical blank of long-term in-situ monitoring of the volume weight dynamics of the soil by a plurality of probes, determines the volume weight value of the non-rigid soil according to a design model based on the acquisition of a soil thermal conductivity value and a soil volume moisture content value, and adopts high-thermal conductivity silicone grease to improve the thermal contact between the soil thermal pulse probe and the soil aiming at the soil thermal pulse probe, thereby overcoming the defect of increased volume weight prediction error caused by non-rigid soil cracking in the original method; in the design, the volume weight prediction deviation caused by the ambient temperature drift in the field monitoring process is corrected by a linear extrapolation method; the whole design method can realize accurate prediction of the volume weight of the non-rigid soil under indoor and outdoor conditions.
Drawings
FIGS. 1a, 1b and 1c are schematic diagrams of a structure of a TP01 heat pulse probe and a 5TE moisture probe connected with a CR3000 data collector respectively;
FIG. 2 is a 5TE soil moisture probe measurement θ v Value and drying theta v A relationship between;
FIG. 3 is a graph showing the relationship between day and night monitoring data and ambient temperature before and after calibration;
fig. 4 shows the relationship between the predicted value and the measured value of the bulk density.
Detailed Description
The following describes the embodiments of the present invention in further detail with reference to the drawings.
In practical application, before a soil moisture probe detects target non-rigid soil, respectively applying the soil moisture probe and a drying method to obtain a measured value of a soil ring cutter sample, and obtaining a linear relation between the measured value and the soil ring cutter sample, wherein the measured value is used for subsequently correcting an error of the soil moisture probe in detecting the target non-rigid soil; after the measurement, the PVC sample was dried at 105 ℃ to a constant weight, and the moisture probe error was corrected by the linear relationship between the dried value and the measured value, as shown in fig. 2.
Before the soil heat pulse probe is used for detecting the target non-rigid soil, the high heat conduction silicone grease is smeared on the surface of the soil heat pulse probe foil, and in the specific implementation, the smearing thickness of the high heat conduction silicone grease is not more than 1mm because the heat pulse probe accurately measures the influence (radius is 4 mm) of the space range of the soil heat characteristic; because the high heat conduction silicone grease has the heat conduction coefficient of 14.8 and 14.8WmK -1 Thermal resistance<0.0028℃W -1 Density of more than 2.6gcm -3 The insulating silicone grease with the viscosity of more than 2500poise is uniformly and thinly coated on the surface of the soil heat pulse probe foil, so that the contact thermal resistance generated between the soil and the probe after the non-rigid soil is dehydrated and cracked can be reduced.
The mounting of the probe is performed as follows.
(1) And (3) for the indoor soil column experiment, filling the soil column to half of the height, placing a TP01 probe foil on the soil surface and ensuring good contact, and then filling the other half of the soil column to the target height. And the soil column is pressed in layers in the filling process, so that the probe foil is ensured to be in good contact with the upper soil layer and the lower soil layer.
(2) In-situ monitoring of different soil layers in the field, a gap is firstly formed in the soil layer by a blade before installation, a probe foil coated with high-heat-conductivity silicone grease is carefully inserted, and a probe base is fixed by wet soil to prevent falling off during filling. After the soil is installed and buried, water is poured on the ground surface for 1-2 times to realize soil layer implementation, so that the purpose of fully contacting the soil with the probe is achieved.
Then based on the simultaneous detection of the thermal conductivity and the volumetric water content of the target non-rigid soil by the soil heat pulse probe and the soil moisture probe, the following steps A to C are executed to realize the soil volume weight value rho of the target non-rigid soil b Is detected.
Step A. Based on the probe sensitivity S of the soil heat pulse probe, the length L of the heating wire in the soil heat pulse probe, the resistance R of the heating wire in the soil heat pulse probe, and the voltage U at two ends of the heating wire in the soil heat pulse probe heater The output voltage U of the probe before and after the heating of the soil heat pulse probe corresponding to the preset heating time of the probe 0 And U 1 The following formula is adopted:
obtaining a soil thermal conductivity value lambda of the target non-rigid soil, wherein S represents the probe sensitivity of the soil heat pulse probe, Q represents the electric power of each meter of heating wire in the soil heat pulse probe, and DeltaU represents U 1 And U 0 The difference between them, and then step B is entered.
In practical application, regarding the detection process of the soil heat pulse probe on the target non-rigid soil in the step a, further designing to reject the detection data of the preset daytime period first, and then for the detection data of the preset nighttime period, according to the following linear extrapolation formula:
U 0 (t)＝at+b
fitting to obtain a trend equation U of the output voltage of the soil heat pulse probe corresponding to the probe before heating along with the change of time (t) 0 (t) correcting the influence of the ambient background temperature on the detected data during the monitoring of the preset night period, as shown in FIG. 3, and applying U according to at therein 1 Result update U of-at 1 Updating and obtaining the output voltage U of the correction probe after the soil heat pulse probe is heated corresponding to the preset probe heating time length 1 And finally, executing the step A to obtain the soil heat conductivity value lambda of the target non-rigid soil, wherein a and b represent equation fitting parameters.
The detection and verification of the soil heat pulse probe on the target non-rigid soil is specifically based on the soil background temperature (T 0 ) Trend equation of change over time (t):
T 0 ＝at+b
the temperature of the heat pulse induction needle (T) during the heating process is deducted v ) The change of the soil background temperature in the air is obtained, and the induction needle temperature change (T) under the single action of pulse heating is obtained c ) And then fitting to obtain the thermal characteristics of the soil:
T c ＝T v -at
in this patent, the TP01 heat pulse probe converts the temperature change (DeltaT) of soil into a minute voltage output value (DeltaU), so that T is v The trend equation of (t) is converted into:
U 0 (t)＝at+b
will T c (t) equation conversion to U 180 (t) equation:
U 1 (t)＝U 1 -at
in practical implementation, based on the acquisition of the soil thermal conductivity value λ of the target non-rigid soil, the design is further based on k=k reference ×T reference Obtaining the soil thermal diffusivity K of the target non-rigid soil, and further obtaining the soil volumetric heat capacity C of the target non-rigid soil according to C=lambda/K; wherein K is reference Represents the thermal diffusivity of a standard reference agar gel at 20 ℃, typically 0.14X10% -6 m 2 s -1 ，T reference Represents the time required for the output voltage to drop to 37% of DeltaU after heating of a standard reference agar gel at 20℃and is typically 19s, deltaU represents U 1 And U 0 And the difference value T represents the response time length of the probe output voltage reduced to 37% of DeltaU after the soil heat pulse probe is heated corresponding to the preset probe heating time length.
And B, according to the soil dielectric constant Eb of the target non-rigid soil obtained by the soil moisture probe, the following formula is adopted:
θ v ＝4.3×10 -6 ×Eb 3 -5.5×10 -4 ×Eb 2 +2.92×10 -2 ×Eb-5.3×10 -2
obtaining the soil volume moisture value theta of the target non-rigid soil v Then step C is entered.
In practical application, the linear relation between the initial soil moisture probe and the measured value of the soil ring cutter sample obtained by the drying method is used for correcting the error of the soil moisture probe on the target non-rigid soil detection.
Step C, according to the soil thermal conductivity value lambda and soil volume moisture content value theta of the target non-rigid soil v For the following model:
iterative calculation to obtain soil total porosity phi of target non-rigid soil and soil volume weight value rho of target non-rigid soil b Wherein α=0.67 f clay +0.24，β＝1.97f sand +1.87ρ b -1.36f sand ρ b -0.95，f sand And f clay Respectively representing sand grain and clay grain content, lambda of target non-rigid soil dry Indicating the dry soil thermal conductivity.
The above design was applied to practice, and a soil heat pulse probe was used as a TP01 heat pulse probe of Hukseflux company, as shown in FIG. 1a, for long-term monitoring of soil heat characteristic values, and the probe was of a foil type design (width 20mm, length 60mm, thickness 0.15 mm). The heating wire is positioned on the central axis of the foil, and two thermopile probes are respectively arranged at 4mm on two sides of the heating wire and are connected in series.
The soil moisture probe is used for measuring soil volume moisture content, and can be commonly used moisture probes such as TDR100, 5TE, EC-5, 315H, etc., specifically METER company 5TE soil moisture probe is selected, as shown in FIG. 1b, the probe adopts Frequency Domain Reflection (FDR) technology, and the apparent dielectric constant of soil is measured according to the propagation frequency of electromagnetic wave in soil, thereby obtaining soil volume moisture content (θ) v ，cm 3 cm -3 )。
In the practical application, in the execution of the steps A to C, a data acquisition device is respectively connected with a soil heat pulse probe and a soil moisture probe and is used for synchronously acquiring the soil heat characteristic and the soil moisture value; when the solar cell is used outdoors, a 12v battery and a solar panel are installed, and a CR3000 data collector of Campbell company is specifically selected and used in the design, as shown in figure 1 c. The data acquisition device is respectively connected with the TP01 soil heat pulse probe and the 5TE moisture probe and is used for synchronously acquiring the soil heat characteristic and the soil moisture value.
And further adopting LoggerNet software to write a control program for controlling the heating time, the measuring interval, the soil thermal characteristic value and the synchronous calculation and output of the soil volume water content value of the thermal pulse probe.
In practical application, the positive electrode of the TP01 probe heating wire power line is connected with a 150 omega resistor in series and then is connected with a switch excitation channel (SW 12V), and the negative electrode is grounded; the positive electrode and the negative electrode of the thermopile signal line are connected with a pair of differential ports; the positive electrode of the heater voltage output line is connected with the differential port, and the negative electrode is grounded; the ground wire is grounded. Each TP01 probe occupies 1.5 pairs of differential channels; the positive electrode and the negative electrode of the 5TE soil moisture probe power line are connected with the switch excitation channel; the data signal line is connected to the single end. Since the moisture probe connector is a 3.5mm cylindrical earphone interface, a connector of corresponding size is additionally arranged to connect with the data collector in order not to damage the structure of the probe itself, as shown in fig. 1 c.
In practice, the program is started every 3 hours at the time intervals set in the above-mentioned design steps a to C. When the program is started, the heating wire is heated for 180s, so that a stable radial temperature difference is generated around the heating wire, and then the following steps A to C are executed based on the simultaneous detection of the soil heat pulse probe and the soil moisture probe on the target non-rigid soil, wherein the relation between the predicted value and the measured value of the volume weight is shown in fig. 4.
The method for in-situ monitoring of the volume weight of the non-rigid soil is designed according to the technical scheme, aims at the problems of increased contact thermal resistance, field temperature drift and the like generated in the expansion and contraction process of the non-rigid soil, adopts brand new design, utilizes a soil heat pulse probe and a soil moisture probe to fill up the technical blank of long-term in-situ monitoring of the volume weight dynamics of the soil by the combination of multiple probes, determines the volume weight value of the non-rigid soil according to a design model based on the acquisition of the soil heat conductivity value and the soil volume moisture content value, and adopts high heat conduction silicone grease to improve the thermal contact between the soil heat pulse probe and the soil aiming at the soil heat pulse probe, so that the defect of increased volume weight prediction error caused by non-rigid soil cracking in the original method is overcome; in the design, the volume weight prediction deviation caused by the ambient temperature drift in the field monitoring process is corrected by a linear extrapolation method; the whole design method can realize accurate prediction of the volume weight of the non-rigid soil under indoor and outdoor conditions.
The embodiments of the present invention have been described in detail with reference to the drawings, but the present invention is not limited to the above embodiments, and various changes can be made within the knowledge of those skilled in the art without departing from the spirit of the present invention.
Claims (8)
1. A method for in-situ monitoring of the volume weight of non-rigid soil, which is characterized in that: based on the simultaneous detection of the thermal conductivity and the volumetric water content of the target non-rigid soil by the soil heat pulse probe and the soil moisture probe, the following steps A to C are executed to realize the soil volume weight value rho of the target non-rigid soil b Is detected;
step A. Based on the probe sensitivity S of the soil heat pulse probe, the length L of the heating wire in the soil heat pulse probe, the resistance R of the heating wire in the soil heat pulse probe, and the voltage U at two ends of the heating wire in the soil heat pulse probe heater The output voltage U of the probe before and after the heating of the soil heat pulse probe corresponding to the preset heating time of the probe 0 And U 1 Obtaining a soil heat conductivity value lambda of target non-rigid soil, and then entering a step B;
step B, obtaining the soil volume moisture value theta of the target non-rigid soil according to the soil dielectric constant Eb of the target non-rigid soil obtained by the soil moisture probe v ThenEntering a step C;
step C, according to the soil thermal conductivity value lambda and soil volume moisture content value theta of the target non-rigid soil v For the following model:
iterative calculation to obtain soil total porosity phi of target non-rigid soil and soil volume weight value rho of target non-rigid soil b Wherein α=0.67 f clay +0.24，β＝1.97f sand +1.87ρ b -1.36f sand ρ b -0.95，f sand And f clay Respectively representing sand grain and clay grain content, lambda of target non-rigid soil dary Indicating the dry soil thermal conductivity.
2. A method of in situ monitoring of non-rigid soil bulk density as claimed in claim 1 wherein: in the step A, the probe sensitivity S based on the soil heat pulse probe, the length L of the heating wire in the soil heat pulse probe, the resistance R of the heating wire in the soil heat pulse probe and the voltage U at two ends of the heating wire in the soil heat pulse probe are adopted heater The output voltage U of the probe before and after the heating of the soil heat pulse probe corresponding to the preset heating time of the probe 0 And U 1 The following formula is adopted:
obtaining a soil thermal conductivity value lambda of the target non-rigid soil, wherein S represents the probe sensitivity of the soil heat pulse probe, Q represents the electric power of each meter of heating wire in the soil heat pulse probe, and DeltaU represents U 1 And U 0 The difference between them, and then step B is entered.
3. A method of in situ monitoring of non-rigid soil bulk density as claimed in claim 1 wherein: in the step B, according to the soil dielectric constant Eb of the target non-rigid soil obtained by the soil moisture probe, the following formula is adopted:
θ v ＝4.3×10 -6 ×Eb 3 -5.5×10 -4 ×Eb 2 +2.92×10 -2 ×Eb-5.3×10 -2
obtaining the soil volume moisture value theta of the target non-rigid soil v Then step C is entered.
4. A method of in situ monitoring of non-rigid soil bulk density as claimed in claim 1 wherein: and (C) detecting the target non-rigid soil by the soil heat pulse probe in the step A, removing detection data of a preset daytime period, and executing the step A according to the detection data of the preset nighttime period to obtain a soil heat conductivity value lambda of the target non-rigid soil.
5. The method for in situ monitoring of the volume weight of non-rigid soil of claim 4, wherein: in the step A, with respect to the detection of the target non-rigid soil by the soil heat pulse probe, for detection data of a preset night time period, the following linear extrapolation formula is adopted:
U 0 (t)＝at+b
fitting to obtain a trend equation U of the output voltage of the soil heat pulse probe corresponding to the probe before heating along with the change of time (t) 0 (t) correcting the influence of the ambient background temperature on the detection data in the monitoring process of the preset night time period, and applying U according to at 1 Result update U of-at 1 Updating and obtaining the output voltage U of the correction probe after the soil heat pulse probe is heated corresponding to the preset probe heating time length 1 Wherein a, b represent equation fitting parameters.
6. A method of in situ monitoring of non-rigid soil bulk density as claimed in claim 1 wherein: before the soil moisture probe detects the target non-rigid soil, the soil moisture probe and the drying method are respectively applied to obtain the measured value of the soil cutting ring sample, and the linear relation between the measured value and the soil cutting ring sample is obtained for subsequently correcting the error of the soil moisture probe on the target non-rigid soil detection.
7. A method of in situ monitoring of non-rigid soil bulk density as claimed in claim 1 wherein: in the step a, based on the obtaining of the soil thermal conductivity value λ of the target non-rigid soil, the method further comprises the following steps of k=k reference ×T reference Obtaining the soil thermal diffusivity K of the target non-rigid soil, and further obtaining the soil volumetric heat capacity C of the target non-rigid soil according to C=lambda/K; wherein K is reference Shows the thermal diffusivity of the standard reference agar gel at 20 ℃, T reference Represents the time period required for the output voltage to drop to 37% of DeltaU after heating of a standard reference agar gel at 20 ℃, deltaU representing U 1 And U 0 And the difference value T represents the response time length of the probe output voltage reduced to 37% of DeltaU after the soil heat pulse probe is heated corresponding to the preset probe heating time length.
8. A method of in situ monitoring of non-rigid soil bulk density as claimed in claim 1 wherein: before the soil heat pulse probe is used for detecting the target non-rigid soil, the high-heat-conductivity silicone grease is smeared on the surface of the soil heat pulse probe foil, and the smearing thickness of the high-heat-conductivity silicone grease is not more than 1mm.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202310086020.4A CN116359277A (en) | 2023-02-09 | 2023-02-09 | Method for in-situ monitoring of volume weight of non-rigid soil |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202310086020.4A CN116359277A (en) | 2023-02-09 | 2023-02-09 | Method for in-situ monitoring of volume weight of non-rigid soil |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN116359277A true CN116359277A (en) | 2023-06-30 |
Family
ID=86926435
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202310086020.4A Pending CN116359277A (en) | 2023-02-09 | 2023-02-09 | Method for in-situ monitoring of volume weight of non-rigid soil |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN116359277A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117191894A (en) * | 2023-11-06 | 2023-12-08 | 湖南省交通规划勘察设计院有限公司 | Soil physical property testing system and method based on thermal response and storage medium |
| CN118090823A (en) * | 2024-04-26 | 2024-05-28 | 江西省水利科学院(江西省大坝安全管理中心、江西省水资源管理中心) | Method for measuring volume weight of mesoscale soil in field by using heat pulse distributed optical fiber |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113008935A (en) * | 2021-03-10 | 2021-06-22 | 中国农业大学 | In-situ measuring device and method for water content, thermal characteristics and electric conductivity of soil |
-
2023
- 2023-02-09 CN CN202310086020.4A patent/CN116359277A/en active Pending
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113008935A (en) * | 2021-03-10 | 2021-06-22 | 中国农业大学 | In-situ measuring device and method for water content, thermal characteristics and electric conductivity of soil |
Non-Patent Citations (4)
| Title |
|---|
| 卢奕丽: "基于土壤热导率定位监测容重的Thermo-TDR技术", 《中国博士学位论文全文数据库 农业科技辑》, 15 August 2017 (2017-08-15), pages 11 - 12 * |
| 张晓: "感热平衡原理测定土壤水分蒸发的改进及分解农田蒸散的实验研究", 《中国博士学位论文全文数据库 农业科技辑》, 15 August 2014 (2014-08-15), pages 28 - 34 * |
| 陈照峰: "《真空绝热板300问》", 31 January 2022, 中国建材工业出版社, pages: 28 - 29 * |
| 高福平等: "《土石坝物理场感知与数值模拟》", 31 December 2019, 河海大学出版社, pages: 29 - 30 * |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117191894A (en) * | 2023-11-06 | 2023-12-08 | 湖南省交通规划勘察设计院有限公司 | Soil physical property testing system and method based on thermal response and storage medium |
| CN117191894B (en) * | 2023-11-06 | 2024-02-23 | 湖南省交通规划勘察设计院有限公司 | Soil physical property testing system and method based on thermal response and storage medium |
| CN118090823A (en) * | 2024-04-26 | 2024-05-28 | 江西省水利科学院(江西省大坝安全管理中心、江西省水资源管理中心) | Method for measuring volume weight of mesoscale soil in field by using heat pulse distributed optical fiber |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN116359277A (en) | Method for in-situ monitoring of volume weight of non-rigid soil | |
| CN206208821U (en) | A kind of native water feature and resistivity joint test device | |
| Kiselev et al. | Automatic meteorological measuring systems for microclimate monitoring | |
| CN107607439B (en) | Automatic identification device and identification method for icing type of power transmission conductor | |
| CN103412244A (en) | Method for measuring space charge characteristics of HVDC XLPE cable under thermal-cold cycling | |
| CN1916615A (en) | Equipment for checking-out effect of heat insulation for building material, checking-out method and evaluation method | |
| CN113008935A (en) | In-situ measuring device and method for water content, thermal characteristics and electric conductivity of soil | |
| CN111679103A (en) | High-voltage cable water-blocking tape electrical performance test system based on three-electrode method | |
| CN212321405U (en) | In-situ high-flux atmospheric corrosion monitoring system | |
| CN2916627Y (en) | Field heat transmission coefficient detector for building walls | |
| CN111337797A (en) | XLPE power cable main insulation non-uniform thermal aging state evaluation method based on modified Debye model | |
| CN111077181B (en) | Device and method for testing thermal contact resistance between outer surface of medium-low voltage cable and soil | |
| CN107748187A (en) | Traditional building wall rate-of-loss of coolant method of testing | |
| CN110568262A (en) | Equipment and method for steady-state detection of heat-insulating coating | |
| CN109425551B (en) | Method for calibrating undisturbed soil of FDR frequency domain reflection type soil moisture sensor | |
| Lachenbruch | A probe for measurement of thermal conductivity of frozen soils in place | |
| CN113252724B (en) | Method for detecting heat preservation performance of external wall | |
| CN103245833B (en) | Conductive asphalt concrete resistivity measurement method based on two-electrode method | |
| CN210604785U (en) | Equipment for detecting heat-insulating coating in stable state | |
| CN114858720A (en) | Photoelectric test system and method for in-situ frozen soil ice water component identification and dynamic tracing | |
| CN115791559A (en) | Method for in-situ monitoring of soil water infiltration amount and wetting front propulsion | |
| CN208420183U (en) | A kind of ground infrared remote sensing surface temperature observation device | |
| CN113970518A (en) | In-situ high-flux atmospheric corrosion monitoring system and monitoring method thereof | |
| CN103837664B (en) | The portable measuring method for measuring of a kind of loess area natural meadow soil moisture content | |
| CN117554418B (en) | Device and method for in-situ measurement of thermal conductivity coefficient at soil point position through penetration |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination |