CN108051473A - Thermo TDR measuring method and device based on probe spacing correction - Google Patents
Thermo TDR measuring method and device based on probe spacing correction Download PDFInfo
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- CN108051473A CN108051473A CN201711092593.9A CN201711092593A CN108051473A CN 108051473 A CN108051473 A CN 108051473A CN 201711092593 A CN201711092593 A CN 201711092593A CN 108051473 A CN108051473 A CN 108051473A
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- 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
Abstract
The present invention provides the thermal pulse otdr measurement method and device corrected based on probe spacing, the described method includes：The temperature curve that the temperature of predetermined position in two inducing probes in the probe changes over time is obtained, there are at least two predeterminated positions in each inducing probes；For any inducing probes, according to the corresponding temperature curve of each predetermined position in any inducing probes, the ratio in each predeterminated position and the probe between the distance of heated probe in any inducing probes is determined；The initial spacing and the ratio of each predeterminated position and the heated probe before the soil to be measured are inserted into according to the probe, determines each predeterminated position to the actual spacing of the heated probe.Method provided by the invention reduces the measurement error generated in practical applications due to inducing probes caused by external cause or heated probe flexural deformation, and soil ice content, thermal characteristics, the accuracy of moisture are calculated so as to improve.
Description
Technical field
The present invention relates to soil physical property fields of measurement, more particularly, to the thermal pulse corrected based on probe spacing-
Otdr measurement method and device.
Background technology
The measure of soil water-heat transfer and soil parameters is various physics, chemistry and life in research soil conditions and soil
The basis of object process.But since soil physical properties has significant room and time variability, i.e. Spatial-Temporal Variability, this leads
The consecutive tracking measurement to soil moisture content, temperature and other physical parameters has been caused to become problem.
There is Thermo TDR (Thermo-Time-Domain Reflectometry, Thermo- at present
TDR) technology (hereinafter referred to as hot-TDR technologies), thermal pulse technology and time domain reflection technology are combined, can be realized
Water content on same position, same volume soil, electrical conductivity, thermal conductivity, the consecutive tracking of thermal capacity and thermal diffusion coefficient measure.
Heat-TDR technologies are most important in the research of soil physical properties, and measurement is also very important in the measurement of soil frozen soil
Technology.
Heat-TDR technologies are combined by thermal pulse technology and time domain reflection technology as a result, having scholar in analysis TDR probes
After thermal pulse sonde configuration feature, heat-TDR measuring devices are designed, this heat-TDR measuring devices are by three parallel spies
Pin forms, and three probes are located in a plane, and length is 40mm, and diameter is 1.3mm, adjacent two stainless steel probes
Spacing is 6mm.Linear heat source and a K-type thermocouple for being located at middle part by insulation resistance wire making is housed in every probe.
Middle part probe is connected with the anode of coaxial cable, and two probes in outside are connected with the cathode of coaxial cable.
But since heat-TDR technologies in the prior art are combined by thermal pulse technology and time domain reflection technology, heat-
The accuracy that the data that TDR measuring devices measure calculate soil parameters will also be limited be subject to both technologies：
Probe flexural deformation is easy to cause when thermal pulse technology is applied in the wild, is become so as to cause probe spacing
Change, and then the data measured using heat-TDR measuring devices can be caused to generate error when calculating soil parameters.Some researches show that
The uncertainty that probe spacing generates 2% generates 4% error when can cause to calculate specific heat capacity.Also some researches show that outsides
Two probes when tilting 1 degree of angle, the soil heat diffusivity and specific heat of calculating can all generate the error of 6%-10%.Together
When, probe length can influence the accuracy of TDR technologies, and probe length is longer, and the moisture measured using TDR technologies is more accurate
Really, but probe is more long simultaneously more being easily deformed causes probe spacing to change, and ultimately results in what is obtained using thermal pulse technology measurement
Data calculate the inaccuracy such as soil thermal characteristics, moisture.Therefore limited by factors above, heat-TDR relatively common at present is surveyed
It measures the probe in device and generally all there was only 4cm long, the far smaller than shortest length required by TDR technologies, limit and utilize TDR skills
Art measures the accuracy of soil water content.On the other hand, heat-TDR measuring devices are applied when frozen soil measures, in the jelly of soil
Melt in alternation procedure, probe spacing also easily changes, and the error that can thus cause the result of measurement is very big, ultimately results in meter
The error of obtained soil ice content is also larger.
The content of the invention
It solves the above problems in order to overcome the problems referred above or at least partly, the present invention provides one kind to be based on probe spacing
The Thermo TDR measuring method and device of correction.
On the one hand, the present invention provides a kind of Thermo TDR measuring method based on probe spacing correction, bags
It includes：
Before probe in Thermo TDR measuring device is inserted into soil to be measured, the probe is inserted into
In the material for knowing thermal conductivity and thermal capacity, it is bent to obtain in the probe the corresponding temperature of predetermined position in two inducing probes
Line；According to each temperature curve, the initial spacing of each predeterminated position and the heated probe is determined.The good initial spacing of calibration
Afterwards, following steps are performed：
S1 after the probe in Thermo TDR measuring device is inserted into soil to be measured, is obtained two in the probe
The temperature curve that the temperature of predetermined position changes over time in a inducing probes, each inducing probes are interior to have at least two in advance
If position；
S2, it is bent according to the corresponding temperature of each predetermined position in any inducing probes for any inducing probes
Line determines the ratio in each predeterminated position and the probe between the distance of heated probe in any inducing probes；
S3, according to the probe be inserted into each predeterminated position and the heated probe before the soil to be measured it is initial between
Away from and the ratio, determine each predeterminated position to the actual spacing of the heated probe；
S4 according to the actual spacing of each predeterminated position to the heated probe, calculates the physical parameter of soil to be measured, institute
Stating the physical parameter of soil to be measured includes：Ice content, thermal diffusion coefficient and the thermal capacity of soil to be measured.
Preferably, S2 is specifically included：
It is bent according to the corresponding temperature of each predetermined position in any inducing probes for any inducing probes
Line determines that the temperature of soil to be measured described in each predetermined position rises to corresponding time duration during maximum；
According to each time duration and the thermal diffusion coefficient of the soil to be measured, determine each in any inducing probes
Ratio in predeterminated position and the probe between the distance of heated probe.
Preferably, the actual spacing of each predeterminated position to the heated probe is determined by the following method：
For any inducing probes, if judging to know, tool there are two predeterminated position, passes through in any inducing probes
Formula ri=ri0+a1*liEach predeterminated position is calculated to the actual spacing of the heated probe, wherein, i represents i-th of default position
It puts, i=1 or 2, riFor the actual spacing of i-th of predeterminated position to the heated probe, ri0It is i-th of predeterminated position to described
The initial spacing of heated probe, liFor i-th of predeterminated position to the distance of the backshank of any inducing probes,P1For r1With r2Ratio.
Preferably, the actual spacing of each predeterminated position to the heated probe is determined by the following method：
For any inducing probes, if judging to know, tool there are three predeterminated position, passes through in any inducing probes
Formula rj=rj0+a2*lj+b*lj 2Each predeterminated position is calculated to the actual spacing of the heated probe, wherein, j is represented j-th
Predeterminated position, j=1 or 2 or 3, rjFor the actual spacing of j-th of predeterminated position to the heated probe, rj0For j-th of default position
It puts to the initial spacing of the heated probe, ljFor j-th of predeterminated position to the distance of the backshank of any inducing probes,P1For r1With r2Ratio, P2For r2With r3Ratio,
On the other hand, the present invention provides a kind of Thermo TDR measuring device based on probe spacing correction, bags
It includes：First inducing probes, the second inducing probes, heated probe, data acquisition unit, correction unit and parameter calculation unit；
At least two temperature measuring units are both provided in first inducing probes and second inducing probes, it is each described
Temperature measuring unit is used to measure the temperature of position；Heater strip is provided in the heated probe, for for the soil to be measured
Earth heats；
The data acquisition unit is used to gather the temperature value that each temperature measuring unit obtains, and the temperature that will be collected
Value input extremely correction unit；
The correction unit is used for according to above-mentioned method, calculates the reality between the temperature measuring unit and the heated probe
Border spacing；
The parameter calculation unit is used for the actual spacing obtained according to the correction unit, calculates soil to be measured
Physical parameter, the physical parameter of the soil to be measured include：Ice content, thermal diffusion coefficient and the thermal capacity of soil to be measured.
Preferably, described device further includes：Time-domain reflectometry unit and coaxial cable；
The outer conductor of described coaxial cable one end is visited respectively with the outer wall of first inducing probes and second sensing
The outer wall connection of pin, the inside conductor of described coaxial cable one end are connected with the heated probe outer wall, and the coaxial cable is another
End is connected with the time-domain reflectometry unit；
The time-domain reflectometry unit is connected with the data acquisition unit.
Preferably, described device further includes：Noise reduction amplifying circuit；
The noise reduction amplifying circuit includes the first capacitance, the second capacitance and noise reduction integrated circuit；
First capacitance is arranged in first inducing probes, and second capacitance is arranged on second sensing and visits
In pin, first capacitance and second capacitance are connected with the heated probe, first capacitance and second electricity
Hold to enhance second reflected signal strength of TDR waveforms；
The noise reduction integrated circuit is connected on the inside conductor between the coaxial cable and the heated probe, the drop
Integrated circuit of making an uproar disturbs for reducing noise signal.
Preferably for any inducing probes in first inducing probes and second inducing probes, described
The temperature that each temperature measuring unit measures in one inducing probes, with any inducing probes middle position described in synchronization
Temperature between relative different be less than 0.01 DEG C.
Thermo TDR measuring method and device provided by the invention based on probe spacing correction, pass through acquisition
The corresponding temperature curve of at least two predetermined positions in each inducing probes, and according to each pre- in any inducing probes
If corresponding temperature curve at position, each predeterminated position and heated probe in the probe in any inducing probes are determined
Distance between ratio；Each predeterminated position and the heated probe before the soil to be measured are inserted into according to the probe
Initial spacing and the ratio, determine each predeterminated position to the actual spacing of the heated probe；According to each default position
The physical parameter for the actual spacing of the heated probe, calculating soil to be measured is put, the physical parameter of the soil to be measured includes：
Ice content, thermal diffusion coefficient and the thermal capacity of soil to be measured.Method provided by the invention reduces in practical applications due to outer
The measurement error generated due to caused inducing probes or heated probe flexural deformation calculates soil ice content, heat so as to improve
Characteristic, the accuracy of moisture.
Description of the drawings
Fig. 1 is a kind of Thermo TDR measuring method based on probe spacing correction provided in an embodiment of the present invention
Flow diagram；
Fig. 2 is to have two in a kind of Thermo TDR measuring device provided in an embodiment of the present invention in inducing probes
Inducing probes flare schematic diagram during a predeterminated position；
Fig. 3 is to have three in a kind of Thermo TDR measuring device provided in an embodiment of the present invention in inducing probes
Inducing probes flare schematic diagram during a predeterminated position；
Fig. 4 is to have three in a kind of Thermo TDR measuring device provided in an embodiment of the present invention in inducing probes
Inducing probes introversion schematic diagram during a predeterminated position；
Fig. 5 is a kind of Thermo TDR measuring device based on probe spacing correction provided in an embodiment of the present invention
Structure chart；
Fig. 6 is a kind of Thermo TDR measuring device based on probe spacing correction provided in an embodiment of the present invention
Structure chart.
Specific embodiment
With reference to the accompanying drawings and examples, the specific embodiment of the present invention is described in further detail.Implement below
Example is not limited to the scope of the present invention for illustrating the present invention.
It is surveyed as shown in Figure 1, one embodiment of the invention provides a kind of Thermo TDR based on probe spacing correction
Amount method, including：
S1 after the probe in Thermo TDR measuring device is inserted into soil to be measured, is obtained two in the probe
The temperature curve that the temperature of predetermined position changes over time in a inducing probes, each inducing probes are interior to have at least two in advance
If position；
S2, it is bent according to the corresponding temperature of each predetermined position in any inducing probes for any inducing probes
Line determines the ratio in each predeterminated position and the probe between the distance of heated probe in any inducing probes；
S3, according to the probe be inserted into each predeterminated position and the heated probe before the soil to be measured it is initial between
Away from and the ratio, determine each predeterminated position to the actual spacing of the heated probe；
S4 according to the actual spacing of each predeterminated position to the heated probe, calculates the physical parameter of soil to be measured, institute
Stating the physical parameter of soil to be measured includes：Ice content, thermal diffusion coefficient and the thermal capacity of soil to be measured.
Specifically, method provided in this embodiment is to Thermo TDR (Thermo-Time-Domain
Reflectometry, Thermo-TDR) measuring device middle probe spacing correction, probe spacing is corrected be due to
When inserting a probe into soil to be measured, it may make probe that bending or offset occur, cause the spacing between adjacent two probe
It changes, initial spacing when making the actual spacing between adjacent two probe and being not inserted into soil to be measured generates deviation, at this time
The corresponding probe spacing of data that Thermo TDR measuring device measurement obtains be actual spacing rather than initial spacing,
If still error will be generated to calculate soil parameters with the original spacing of probe.
So the present invention is realized using Thermo TDR measuring device, in Thermo TDR measuring device
With probe, probe specifically may include two inducing probes and a heated probe, and two inducing probes are separately positioned on heating
The both sides of probe, and the distance between two inducing probes and heated probe are known as initial spacing when will be not inserted into soil to be measured,
The distance between latter two inducing probes of soil to be measured and heated probe will be inserted into and be known as actual spacing.Thermo TDR
Probe in measuring device can be used as thermal pulse probe and TDR probes simultaneously.
After the probe of device is inserted into soil to be measured, to determine actual spacing, obtain first in two inducing probes
The temperature curve that the temperature of predetermined position changes over time, each inducing probes are interior to have at least two predeterminated positions.In this regard,
It should be noted that being provided with heater strip in centrally located heated probe, heater strip generates heat after being powered, and makes treating for surrounding
Soil moisture rise is surveyed, the temperature curve of acquisition is the curve that temperature changes over time, and can in each predetermined position
Generate a temperature curve.In the present embodiment, the selection needs of predeterminated position meet some requirements in each inducing probes,
The relative deviation of the temperature of each predetermined position got in synchronization and the temperature of the inducing probes middle position
It is less than 0.01 DEG C.
In the present embodiment, by obtaining the corresponding temperature curve of at least two predetermined positions in each inducing probes, and
According to the corresponding temperature curve of each predetermined position in any inducing probes, determine each in any inducing probes
Ratio in predeterminated position and the probe between the distance of heated probe；Before the soil to be measured being inserted into according to the probe
Initial spacing and the ratio of each predeterminated position with the heated probe, determine each predeterminated position to the heating
The actual spacing of probe.Bearing calibration provided by the invention reduces in practical applications due to inducing probes caused by external cause
Or heated probe flexural deformation and the measurement error that generates, calculate soil ice content, thermal characteristics, the standard of moisture so as to improve
True property.
On the basis of above-described embodiment, S2 is specifically included：
It is bent according to the corresponding temperature of each predetermined position in any inducing probes for any inducing probes
Line determines that the temperature of soil to be measured described in each predetermined position rises to corresponding time duration during maximum；
According to each time duration and the thermal diffusion coefficient of the soil to be measured, determine each in any inducing probes
Ratio in predeterminated position and the probe between the distance of heated probe.
Specifically, due to being provided with heater strip in heated probe, a linear heat source can be regarded as.Determined according to heat transfer
Rule, in an infinitely great uniform isothermal medium, the thermal pulse that linear heat source is sent is radial to infarctional.For soil
Certain point in earth, temperature, which changes over time, to be represented by equation below (1)：
Wherein, Δ T (r, t) changes with time value for temperature, unit for DEG C, Ei is exponential integral, and α is thermal diffusion system
Number, unit m2s-1, ρ is the soil weight, and unit is kg m-3, c is specific heat capacity appearance, and unit is J kg-1K-1, ρ c are Soil Thermal
Capacity, unit are J m-3K-1, t0For the electric-heating-wire-heating time, unit s, q ' for unit length in the unit time heating wire institute
The heat of release, unit are J m-1s-1.Heating wire is from 0 to t0Period in continuous heating, probe can be obtained using above formula
The numerical value that predetermined position temperature rises when spacing is r.
Wherein,
Wherein, Δ TmBe temperature rise maximum, tmIt is and Δ TmAt the time of corresponding.
According to formula (1), it can obtain representing the temperature curve of temperature change value and time Relationship.According to obtained temperature
It writes music line, you can determine that the temperature of each predetermined position rises to corresponding time duration during maximum.
The temperature value of each predetermined position can be obtained by the temperature measuring unit for being arranged on the predetermined position, and temperature measuring unit can
Thermistor or thermocouple are selected, also or all other suitable temperature elements.
According to the time duration tmWith the expression formula (2) of the thermal diffusion coefficient α of the soil to be measured, it may be determined that described
Ratio in any inducing probes in each predeterminated position and the probe between the distance of heated probe.
By taking one of inducing probes as an example, tool is there are two predeterminated position in the inducing probes, on each predeterminated position
Temperature measuring unit there are one setting.It is each default after the probe in Thermo TDR measuring device is inserted into soil to be measured
It can obtain a temperature curve at position, also there are one corresponding Δ TmAnd tm,
Define tmiCorresponding time duration when rising to highest for the temperature that i-th of temperature measuring unit measures corresponds to what is obtained
Thermal diffusion coefficient is represented by：
Wherein, i=1,2 or 3, riFor i-th of temperature measuring unit and the distance of heated probe；And have：
Assuming that soil to be measured is uniform, then the thermal diffusion coefficient α that each temperature measuring unit measurement obtains1、α2And α3It is phase
With, there will be following relations：
η1、η2、η3Between relation be represented by：
Wherein, P1For r1With r2Between ratio, P2For r2With r3Between ratio.
The ratio between the distance of heated probe in each predeterminated position and the probe is obtained.It similarly can obtain another
Ratio in one inducing probes in each predeterminated position and the probe between the distance of heated probe, this will not be repeated here.
On the basis of above-described embodiment, the probe in Thermo TDR measuring device is inserted into soil to be measured
Before, it further includes：Obtain each predeterminated position and the initial spacing of the heated probe in each inducing probes.
Specifically, the probe in the Thermo TDR measuring device can be inserted into known thermal conductivity and thermal capacitance
In the material of amount, the corresponding temperature curve of predetermined position in two inducing probes is obtained in the probe；According to each temperature
Curve determines the initial spacing of each predeterminated position and the heated probe.Preferably, agar material may be selected.
On the basis of above-described embodiment, S3 is specifically included：
According to initial distance corresponding with each predeterminated position and the ratio, determine each predeterminated position to described
The actual spacing of heated probe.
Specifically, the actual spacing of each predeterminated position to the heated probe is determined by the following method：
For any inducing probes, if judging to know, tool there are two predeterminated position, passes through in any inducing probes
Formula ri=ri0+a1*liEach predeterminated position is calculated to the actual spacing of the heated probe, wherein, i represents i-th of default position
It puts, i=1 or 2, riFor the actual spacing of i-th of predeterminated position to the heated probe, ri0It is i-th of predeterminated position to described
The initial spacing of heated probe, liFor i-th of predeterminated position to the distance of the backshank of any inducing probes,P1For r1With r2Ratio.
For any inducing probes, if judging to know, tool there are three predeterminated position, passes through in any inducing probes
Formula rj=rj0+a2*lj+b*lj 2Each predeterminated position is calculated to the actual spacing of the heated probe, wherein, j is represented j-th
Predeterminated position, j=1 or 2 or 3, rjFor the actual spacing of j-th of predeterminated position to the heated probe, rj0For j-th of default position
It puts to the initial spacing of the heated probe, ljFor j-th of predeterminated position to the distance of the backshank of any inducing probes,P1For r1With r2Ratio, P2For r2With r3Ratio,
Specifically, if judging to know, tool is there are two predeterminated position in a certain inducing probes, as shown in Fig. 2, in heated probe 1
It is provided with heater strip 4, is correspondingly arranged on heating unit 5 and heating unit 6 on predeterminated position in inducing probes 2, heating unit 5 arrives
The distance of heated probe 1 is initial spacing r10, the distance of heating unit 6 to heated probe 1 is initial spacing r20, pop one's head in and do not insert
When entering into soil to be measured, the distance of 5 position of heating unit and the backshank of inducing probes 2 is l1, 6 institute of heating unit is in place
It is l to put with the distance of the backshank of inducing probes 22。
Can be deformed upon after probe is inserted into soil to be measured, make each heating unit to heated probe distance simultaneously
It is not initial spacing, but becomes r respectively1And r2, pitch changing value is respectively Δ r1With Δ r2, then have：
ri=ri0+δri, (i=1,2) (8)
Wherein, δ riAbsolute value be equal to Δ ri, the predetermined position where i-th of temperature measuring unit is away between heated probe 1
Away from variation δ riCan approximate representation be：
δri=a1*li, (i=1,2) (9)
Wherein, a1For unknowm coefficient.
It can be drawn according to formula (7), formula (8) and formula (9)：
It is obtained by formula (10)P1For r1With r2Ratio.The result acquired is substituted into formula (8)
With in formula (9) i.e. can obtain actual spacing.
It is bent it should be noted that Fig. 2 illustrates only inducing probes 2 to the direction away from heated probe 1, but due to formula
(8) the δ r iniIt can just bear, therefore method provided by the invention is equally applicable to inducing probes 2 to close to the side of heated probe 1
To the situation of bending, specific implementation step is identical with above-mentioned steps, and details are not described herein.
Specifically, if judging to know, tool is there are three predeterminated position in a certain inducing probes, as shown in figure 3, on the basis of Fig. 2
On, a heating unit 7 is with the addition of, the distance of heating unit 7 to heated probe 1 is initial spacing r30, probe is not inserted into treating
When surveying in soil, the distance of 7 position of heating unit and the backshank of inducing probes 2 is l3。
It can be deformed upon after probe is inserted into soil to be measured, the distance of heating unit 5 to heated probe is not just
Beginning spacing r10, but become r1, the distance of heating unit 6 to heated probe 1 is not initial spacing r20, but become r2, add
Hot cell 7 arrives the distance of heated probe 1 nor initial spacing r30, but become r3, pitch changing value is respectively Δ r1、
Δr2With Δ r3, then have：
rj=rj0+δrj, (j=1,2,3) (11)
Wherein, δ rjAbsolute value be equal to Δ rj, the predetermined position where j-th of temperature measuring unit is away between heated probe 1
Away from variation δ ri, can approximate representation be：
δrj=a2*lj+b*lj 2, (j=1,2,3) (12)
Wherein, a2For unknowm coefficient.
It can be drawn according to formula (7), formula (11) and formula (12)：
It is obtained by formula (13) P1For r1With r2Ratio, P2For r2With r3Ratio.It will ask
The result obtained substitutes into formula (11) and formula (12) and can obtain actual spacing.
Fig. 4 is tool in inducing probes there are three during predeterminated position, after probe is inserted into soil to be measured inducing probes 2 to
Situation about being bent close to the direction of heated probe 1.Specific bearing calibration is with above-mentioned inducing probes 2 to the side away from heated probe 1
Identical to the situation of bending, details are not described herein by the present invention.
On the basis of above-described embodiment, when having in inducing probes more than three predeterminated positions, each predeterminated position
The temperature value at place can be obtained by the temperature measuring unit for being arranged on the predetermined position, and three default positions are randomly choosed from temperature measuring unit
The temperature measuring unit at place is put, actual spacing can be obtained using the above method, details are not described herein by the present invention.
Explanation is needed exist for, the distance of heating unit of the present invention to heated probe is actually that heating unit arrives
The distance of heater strip in heated probe, heated probe and inducing probes of the present invention are each attached on fixed cell 11, are visited
The postamble of pin refers to probe and the position of the plane contact of fixed cell 11.
On the basis of above-described embodiment, S4 is specifically included：According to each predeterminated position to the reality of the heated probe
Spacing, calculates the physical parameter of soil to be measured, and the physical parameter of the soil to be measured includes：The ice content of soil to be measured, thermal expansion
Dissipate coefficient and thermal capacity.
Specifically, obtained actual spacing is substituting in the corresponding temperature curve formula (1) of each predetermined position, and
The thermal diffusion coefficient of soil to be measured and soil heat capacity to be measured can be obtained respectively using formula (2) and formula (3).
For calculating the ice content of soil to be measured, measured first by the TDR in Thermo TDR measuring device single
Member calculates the moisture θ of soilw, specific method is as follows:
For the probe of known length (L), TDR measuring units are sent in probe electromagnetic wave propagation speed VpIt can be with table
It is shown as：
Times of the wherein t between two secondary reflection of electromagnetic wave, wherein first reflection be contacted in electromagnetic wave rigid connection it is to be measured
It is reflected during soil, the second secondary reflection is reflected in the syringe needle of electromagnetic wave to tat probe.When electromagnetic wave is in non-homogeneous soil to be measured
During middle propagation, spread speed is decided by the dielectric constant K of the soil to be measureda, wherein having：
Wherein, c be the speed of electromagnetic wave in a vacuum, c=3 × 108m s-1, formula (15) is substituting to formula (14) can
：
TDR units calculate the formula of the moisture of soil to be measured：
The dielectric constant K that formula (16) is calculateda, formula (17) is substituting to, finally obtains the moisture of soil to be measured
Content.
The ice content formula of soil to be measured is as follows：
C=ρbcs+θwρwcw+faρaca+θiρici (18)
Wherein, C be soil to be measured thermal capacity, faFor the volume fraction shared by soil air to be measured, θwFor soil to be measured
Moisture, θiFor the ice volume content of soil to be measured, θwWith θiUnit be m3m-3；ρbIt is single for the unit weight of soil to be measured
Position is kg m-3, csFor the specific heat capacity of solid in soil to be measured, unit is J kg-1K-1, ρw, ρaAnd ρiRespectively moisture, air and
The density of ice, unit are kg m-3；cw、caAnd ciThe respectively specific heat capacity of moisture, air and ice, unit are J kg-1K-1。
It is generally all omitted for air item, therefore above formula is reduced to：
C=ρbcs+θwρwcw+θiρici (19)
Formula (17) is substituting to formula (19), and the thermal capacity of soil to be measured is obtained according to formula (3), utilizes conventional side
Method can obtain ρb、cs, the ice content θ of soil to be measured can be finally obtained according to formula (19)i：
As shown in figure 5, another embodiment of the present invention provides a kind of Thermo TDR based on probe spacing correction
Measuring device, including：First inducing probes 51, the second inducing probes 53, heated probe 52, data acquisition unit 54, correction are single
Member 55 and parameter calculation unit 56；
At least two temperature measuring units are both provided in first inducing probes 51 and second inducing probes 53, each
The temperature measuring unit is used to measure the temperature of position；Heater strip is provided in the heated probe 52, for for described in
Soil heating to be measured；
The data acquisition unit 54 is used to gather the temperature value that each temperature measuring unit obtains, and the temperature that will be collected
Angle value is inputted to correction unit 55；
The correction unit 55 is used for according to above-mentioned bearing calibration, calculates each temperature measuring unit and the heated probe
Between actual spacing；
The parameter calculation unit 56 is used for the actual spacing obtained according to the correction unit 55, calculates soil to be measured
The physical parameter of earth, the physical parameter of the soil to be measured include：Ice content, thermal diffusion coefficient and the thermal capacity of soil to be measured.
On the basis of above-described embodiment, the Thermo TDR measuring device based on probe spacing correction further includes：
Time-domain reflectometry unit and coaxial cable；
The outer conductor of described coaxial cable one end is visited respectively with the outer wall of first inducing probes and second sensing
The outer wall connection of pin, the inside conductor of described coaxial cable one end is connected with the heated probe outer wall, the coaxial cable it is another
One end is connected with the time-domain reflectometry unit；
The time-domain reflectometry unit is connected with the data acquisition unit.
On the basis of above-described embodiment, the Thermo TDR measuring device based on probe spacing correction further includes：
Noise reduction amplifying circuit；
The noise reduction amplifying circuit includes the first capacitance, the second capacitance and noise reduction integrated circuit；
First capacitance is arranged in first inducing probes, and second capacitance is arranged on second sensing and visits
In pin, first capacitance and second capacitance are connected with the heated probe, first capacitance and second electricity
Hold to enhance second reflected signal strength of TDR waveforms；
The noise reduction integrated circuit is connected on the inside conductor between the coaxial cable and the heated probe, the drop
Integrated circuit of making an uproar disturbs for reducing noise signal.
On the basis of above-described embodiment, for any sense in first inducing probes and second inducing probes
Answer probe, the temperature that each temperature measuring unit measures in any inducing probes, with any sensing described in synchronization
Relative different between the temperature of probe middle position is less than 0.01 DEG C.
Specifically, as shown in fig. 6, the Thermo TDR measuring device based on probe spacing correction in Fig. 6 includes adding
Thermal probe 1, inducing probes 2, inducing probes 3, fixed cell 11, TDR measuring units 29, data collecting instrument 24 and power supply 23.
Wherein, heater strip 4 is provided in heated probe 1, heater strip 4 is nichrome material.Heater strip 4 is led by external
Line 19 is connected with power supply 23.Reference resistance 25 is also associated between relay 26 and power supply 23, the resistance value of reference resistance 25 is 1
Ω.The both ends of reference resistance 25 are connected with data collecting instrument 24.Heated probe 1, inducing probes 2 and inducing probes 3 are each attached to
On fixed cell 11, coaxial cable 12 is provided in fixed cell 11, the outer conductor of 12 one end of coaxial cable is visited respectively with sensing
Pin 2 is connected with the outer wall of inducing probes 3, and the inside conductor of 12 one end of coaxial cable is connected with 1 outer wall of heated probe.Inducing probes 2
With a capacitance 27 is respectively arranged in inducing probes 3, capacitance 27 is connected by conducting wire with heated probe 1, to enhance TDR waveforms
Second reflected signal strength, and an external noise reduction integrates electricity on the inside conductor between coaxial cable 12 and heated probe 1
Road.Explanation is needed exist for, first reflected signal of TDR waveforms refers to：After probe is inserted into soil to be measured, TDR is surveyed
The signal that the electromagnetic wave that amount unit 29 emits is reflected when rigid connection contacts soil to be measured；Second reflected signal of TDR waveforms be
Refer to：The electromagnetic wave that TDR measuring units 29 emit to tat probe syringe needle when the signal that reflects.Second reflected signal of TDR waveforms
Intensity is the intensity of second reflected signal detected.
Noise reduction integrated circuit is by control circuit 13, CMOS (Complementary Metal Oxide
Semiconductor, complementary metal oxide semiconductor) turn ECL (Emitter Coupled Logic, emitter-coupled logic
Lock) unit 14, ECL15, delayer 16, microprocessor 17, ECL18 and clock 28 form.It, can by external noise reduction integrated circuit
To reduce noise signal interference.
Inside conductor in heated probe 1 is connected by 19 both ends of external wire with power supply 23, relay 26 respectively.Sensing is visited
The inside conductor of the temperature measuring unit 5,6,7 set in the axial direction in pin 2 is respectively by conducting wire 20,21,22 and data collecting instrument 24
It connecting, the inside conductor of the temperature measuring unit 8,9,10 set in the axial direction in inducing probes 3 is connected respectively with data collecting instrument 24,
Since connection mode is identical with the inside conductor connection mode of the temperature measuring unit 5,6,7 in inducing probes 2, do not draw again herein.This
By the use of data collecting instrument as data acquisition unit in embodiment.
TDR measuring units 29 are connected by conducting wire 30 with 12 other end of coaxial cable.
In order to increase signal-to-noise ratio, temperature measuring unit 5, temperature measuring unit 6 and temperature measuring unit 7 are on the axis direction of inducing probes 2
Distance to ensure as optimal pre-determined distance so that above-mentioned updating formula can be used normally, and each temperature measuring unit
Position will cause the temperature that each temperature measuring unit measures, with the temperature of 2 middle position of synchronization inducing probes it
Between relative deviation to be less than 0.01 DEG C.2 centre position of inducing probes is referred between the syringe needle and backshank of inducing probes 2
Centre position on length direction.
The Thermo TDR measuring device based on probe spacing correction provided in the present embodiment, is adopted by data
Collection instrument gathers the data that temperature measuring unit measurement obtains in each probe, each probe, and enters data into correction unit, obtains reality
Spacing, parameter calculation unit are treated according to the obtained actual spacing of correction unit and the measurement result of TDR measuring units, calculating
The physical parameter of soil is surveyed, device provided by the invention can accurately draw and bend on the spot using middle probe, tilt it
Actual spacing afterwards, and soil parameters is calculated exactly with reference to other parameters.
On the basis of above-described embodiment, length and the diameter of heated probe 1 meet the wireless wire model of thermal pulse, and
Length meets the electromagnetic wave propagation intensity that TDR measuring units 29 send, the resolution ratio of data collecting instrument 24 and coaxial simultaneously
Cable 12, conducting wire 30, each connector and the dielectric absorption in soil to be measured decay intensity requirement.
On the basis of above-described embodiment, with thermal conductivity is higher and the preferable material of electrical insulating property, curable sealing material
Expect filling into fixed module 11, to ensure to insulate with ambient enviroment, preferably the sealing material is epoxy resin, can be according to actual need
Select other materials met.
On the basis of above-described embodiment, the fixed module is filling by the curable sealing material to insulate.
On the basis of above-described embodiment, hollow stainless steel tube that the heated probe and inducing probes are.
The present invention's can correct the Thermo TDR measuring device of spacing and its correction side of middle probe spacing in situ
Method can correct the spacing of inducing probes and heated probe, by setting at least two temperature measuring units in inducing probes on the spot
Draw the actual spacing of inducing probes and heated probe in measurement exactly, reduce thermal pulse method in practical applications by
In the measurement error that the reasons such as inducing probes or heated probe bending, inclination generate, so as to improve soil ice content, Re Te
Property, the accuracy of moisture, and apparatus structure provided by the invention is simple, measurement quick and precisely, low cost, available for original
Position monitoring in real time.
Finally, method of the invention is only preferable embodiment, is not intended to limit the scope of the present invention.It is all
Within the spirit and principles in the present invention, any modifications, equivalent replacements and improvements are made should be included in the protection of the present invention
Within the scope of.
Claims (9)
1. a kind of Thermo TDR measuring method based on probe spacing correction, which is characterized in that including：
S1 after the probe in Thermo TDR measuring device is inserted into soil to be measured, obtains two senses in the probe
The temperature curve that the temperature of predetermined position in probe is answered to change over time, each inducing probes are interior to have at least two default positions
It puts；
S2, for any inducing probes, according to the corresponding temperature curve of each predetermined position in any inducing probes, really
Ratio in fixed any inducing probes in each predeterminated position and the probe between the distance of heated probe；
S3, according to the probe be inserted into the initial spacing of each predeterminated position and the heated probe before the soil to be measured,
And the ratio, determine each predeterminated position to the actual spacing of the heated probe；
S4 according to the actual spacing of each predeterminated position to the heated probe, calculates the physical parameter of soil to be measured, described to treat
Surveying the physical parameter of soil includes：Ice content, thermal diffusion coefficient and the thermal capacity of soil to be measured.
2. according to the method described in claim 1, it is characterized in that, S2 is specifically included：
For any inducing probes, according to the corresponding temperature curve of each predetermined position in any inducing probes,
Determine that the temperature of soil to be measured described in each predetermined position rises to corresponding time duration during maximum；
According to each time duration and the thermal diffusion coefficient of the soil to be measured, determine each default in any inducing probes
Ratio in position and the probe between the distance of heated probe.
3. according to the method described in claim 1, it is characterized in that, the probe in Thermo TDR measuring device is inserted
Enter to soil to be measured, further include：
The probe is inserted into the material of known thermal conductivity and thermal capacity, obtained pre- in two inducing probes in the probe
If corresponding temperature curve at position；
According to each temperature curve, the initial spacing of each predeterminated position and the heated probe is determined.
4. method according to any one of claim 1-3, which is characterized in that each predeterminated position to the heating
The actual spacing of probe is determined by the following method：
For any inducing probes, if judging to know, tool there are two predeterminated position, passes through formula r in any inducing probesi
=ri0+a1*liEach predeterminated position is calculated to the actual spacing of the heated probe, wherein, i represents i-th of predeterminated position, i
=1 or 2, riFor the actual spacing of i-th of predeterminated position to the heated probe, ri0For i-th of predeterminated position to the heating
The initial spacing of probe, liFor i-th of predeterminated position to the distance of the backshank of any inducing probes,
P1For r1With r2Ratio.
5. method according to any one of claim 1-3, which is characterized in that each predeterminated position to the heating
The actual spacing of probe is determined by the following method：
For any inducing probes, if judging to know, tool there are three predeterminated position, passes through formula r in any inducing probesj
=rj0+a2*lj+b*lj 2Each predeterminated position is calculated to the actual spacing of the heated probe, wherein, j represents j-th of default position
It puts, j=1 or 2 or 3, rjFor the actual spacing of j-th of predeterminated position to the heated probe, rj0For j-th of predeterminated position to institute
State the initial spacing of heated probe, ljFor j-th of predeterminated position to the distance of the backshank of any inducing probes,P1For r1With r2Ratio, P2For r2With r3Ratio,
6. a kind of Thermo TDR measuring device based on probe spacing correction, which is characterized in that including：First sensing
Probe, the second inducing probes, heated probe, data acquisition unit, correction unit and parameter calculation unit；
At least two temperature measuring units are both provided in first inducing probes and second inducing probes, each thermometric
Unit is used to measure the temperature of position；Heater strip is provided in the heated probe, for adding for the soil to be measured
Heat；
The data acquisition unit is used to gather the temperature value that each temperature measuring unit obtains, and the temperature value collected is defeated
Enter to correction unit；
The correction unit is used to, according to the method as any one of claim 1-5, calculate the temperature measuring unit and institute
State the actual spacing between heated probe；
The parameter calculation unit is used for the actual spacing obtained according to the correction unit, calculates the physics of soil to be measured
Parameter, the physical parameter of the soil to be measured include：Ice content, thermal diffusion coefficient and the thermal capacity of soil to be measured.
7. device according to claim 6, which is characterized in that further include：Time-domain reflectometry unit and coaxial cable；
The outer conductor of described coaxial cable one end respectively with the outer wall of first inducing probes and second inducing probes
Outer wall connects, and the inside conductor of described coaxial cable one end is connected with the heated probe outer wall, the coaxial cable other end and
The time-domain reflectometry unit is connected；
The time-domain reflectometry unit is connected with the data acquisition unit.
8. device according to claim 6, which is characterized in that further include：Noise reduction amplifying circuit；
The noise reduction amplifying circuit includes the first capacitance, the second capacitance and noise reduction integrated circuit；
First capacitance is arranged in first inducing probes, and second capacitance is arranged on second inducing probes
Interior, first capacitance and second capacitance are connected with the heated probe, first capacitance and second capacitance
For enhancing second reflected signal strength of TDR waveforms；
The noise reduction integrated circuit is connected on the inside conductor between the coaxial cable and the heated probe, the noise reduction collection
It is disturbed into circuit for reducing noise signal.
9. according to the device any one of claim 6-8, which is characterized in that for first inducing probes and described
Any inducing probes in second inducing probes, the temperature that each temperature measuring unit measures in any inducing probes,
Relative different between the temperature of any inducing probes middle position described in synchronization is less than 0.01 DEG C.
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| CN115355958A (en) * | 2022-07-29 | 2022-11-18 | 鲁东大学 | Whole-interval heat pulse liquid flow measuring device and method |
| CN115355958B (en) * | 2022-07-29 | 2023-08-22 | 鲁东大学 | Full-interval heat pulse liquid flow measuring device and method |
| CN116413310A (en) * | 2023-06-12 | 2023-07-11 | 深圳大学 | Test device and method for measuring heat conductivity coefficient under dynamic temperature condition |
| CN116413310B (en) * | 2023-06-12 | 2023-08-22 | 深圳大学 | Test device and method for measuring heat conductivity coefficient under dynamic temperature condition |
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Application publication date: 20180518 |