CN105738479B - The method and device of flexure element test geomaterial small strain viscoelastic parameters - Google Patents
The method and device of flexure element test geomaterial small strain viscoelastic parameters Download PDFInfo
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- CN105738479B CN105738479B CN201610096076.8A CN201610096076A CN105738479B CN 105738479 B CN105738479 B CN 105738479B CN 201610096076 A CN201610096076 A CN 201610096076A CN 105738479 B CN105738479 B CN 105738479B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
- G01N29/04—Analysing solids
- G01N29/07—Analysing solids by measuring propagation velocity or propagation time of acoustic waves
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
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- G01N2291/02—Indexing codes associated with the analysed material
- G01N2291/028—Material parameters
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Abstract
The invention discloses a kind of method and devices of flexure element test geomaterial small strain viscoelastic parameters.Process prepares cylindrical sample first, and test obtains its density；Cylindrical sample is shelved in foam rods, flexure element and reception flexure element will be motivated to be connected to the both ends of cylindrical sample, the piezoelectric ceramics of two flexure elements is inserted into same depth in cylindrical sample；Flexure element excitation is motivated to issue pulse signal, signal is through propagation in cylindrical sample and reflects, and is received flexure element record and receives, and the pumping signal of sending and reception signal are obtained the viscoelastic parameters including elastic parameter and damping ratio after processing.Compared with current material viscoelastic parameters test method, the advantages that present invention has the ability of test small strain viscoelastic parameters, and has test device simple, and testing efficiency is high, and physical relation is clear.
Description
Technical field
The present invention relates to material parameter test method and device, and in particular to a kind of flexure element tests geomaterial
It is viscous to obtain its small strain by geomaterial wave testing and analysis processing for the method and device of small strain viscoelastic parameters
Elastic parameter.
Background technique
Carry out Dynamic Analysis of Foundation or when dynamic model test, the dynamic stress-strain relationship of geomaterial often by
It is reduced to ideal viscoelastic model, mechanical characteristic is characterized by elasticity modulus and damping ratio；Material viscoelasticity parameter testing
Accuracy will directly affect the degree of reliability of kinematic analysis or test.For uniformly continuous and the biggish material of rigidity is (such as complete
Whole rock), cantilever beam vibratory drilling method can be used in the test of viscoelastic parameters, which defines and test result test sample
The influence of vibration frequency and amplitude is smaller.And soil body material is due to being discrete multiphase medium, and not applicable cantilever method, it is small
Viscoelastic parameters test need to pass through resonant column test or free vibration column test under strained condition.The testing procedure of resonant column test is opposite
Complexity needs to obtain sample resonant frequency by way of frequency sweep, calculates the elastic parameter of sample material；Finding resonant frequency
When, frequency sweep plays the role of pre- vibration to sample and encrypts, and it is bigger than normal to will cause test material elasticity modulus test result；Resonant column test side
Boundary's condition is unknown, and the vibration characteristics of excitational equipment itself will affect test result.And free vibration column test is only to sample single static(al)
Load, obtains its resonant frequency by sample self-vibration characteristic, test method is convenient compared with resonant column test；Make without vibration encryption in advance
With the influence to sample is smaller, and measuring accuracy is compared with resonant column test height.But still that there are boundary conditions is unknown for free vibration column test
Disadvantage, test result needs are modified.In summary, the survey of geomaterial viscoelastic parameters under the conditions of small strain
Examination still lacks a kind of unification, simplicity, reliable method.
Summary of the invention
In order to solve the problems, such as background technique, the invention proposes a kind of flexure element test geomaterial is small
Strain the method and device of viscoelastic parameters: only by a wave testing, can analytical calculation geomaterial viscoplasticity
Parameter simplifies the test mode method of geomaterial parameter；Experimental rig is simple, it is only necessary to which flexure element corollary apparatus can be complete
At test.
The technical solution adopted by the invention is as follows:
One, a kind of method of flexure element test geomaterial small strain viscoelastic parameters, comprising the following steps:
1) column type geomaterial sample is prepared, obtains its density of material by weighing, surveying volume；
2) excitation flexure element and reception flexure element are connected to cylindrical sample by fixed column type geomaterial sample
Both ends, the piezoelectric ceramics of two flexure elements is inserted into same depth in column type geomaterial sample；
3) signal generator generates pulse voltage signal as pumping signal, is divided into two-way, wherein all the way through power amplification
It is sent to oscillograph recording after device amplification, another way leads to excitation flexure element, motivates in column type geomaterial sample
Elastic body wave, bulk wave approximate one-dimensional propagation in column type test sample, the higher shearing wave of energy are met styletable free boundary and can be sent out
Raw to reflect, the fluctuation for generating reflection in test process in sample is received flexure element and successively receives, and is converted into voltage signal through electricity
As signal is received after the amplification of lotus amplifier, it is sent to oscillograph recording.
4) analysis receives signal, by perfect elastic body wave theory and one-dimensional wave theory, calculates and obtains geotechnical engineering
Material small strain viscoelastic parameters.
The elastic parameter is specifically calculated in the following ways and is obtained: just reaching signal according to pumping signal and elastic body wave
Time difference obtains the bulk wave velocity of wave that signal is propagated in column type test sample, then according to perfect elastic body wave theory by following
Equations obtain the elastic parameter of the column type test sample material, and elastic parameter includes modulus of shearing, Young's modulus and Poisson
Than:
G=ρ Vs 2
Wherein, G indicates modulus of shearing, and E indicates Young's modulus, and μ indicates Poisson's ratio, and ρ indicates density of material, VpFor ground work
Journey material compresses velocity of wave propagation, VsVelocity of wave propagation is sheared for geomaterial.
The geomaterial compresses velocity of wave propagation VpVelocity of wave propagation V is sheared with geomaterialsIt is respectively adopted
Following formula calculates:
Wherein, T0For the take-off time point of pumping signal, TpFor the first passage time point of compressional wave, TsFirst for shearing wave reaches
Time point, t0The system delay of circuit is tested between excitation flexure element and reception flexure element, L is the length of column type test sample
Degree, l are the insertion depth of flexure element piezoelectric ceramics.
The elastic parameter is specifically calculated in the following ways and obtained: analysis receives in signal and successively reaches shearing wave
Attenuation is calculated using the following equation the damping ratio for obtaining geomaterial material in conjunction with the propagation distance of shearing wave:
Wherein, VsGeomaterial shears velocity of wave propagation, and S indicates attenuation coefficient (αf) with the relation curve of frequency (f)
Slope at main energy frequency range.
Attenuation coefficient (the αf) with the slope S of the relation curve of frequency (f) at main energy frequency range use following formula
It calculates:
Wherein, Δ αfIt is shearing wave in the variable quantity of main energy frequency range attenuation coefficient, Δ f is the main energy frequency range of shearing wave
Section is long.
It keeps the cylindrical sample hanging as far as possible when test, prevents bulk wave from transmiting in communication process, cause to calculate
Obtained damping ratio is bigger than normal.
Square wave or sine wave can be used in the pulse signal.
Two, a kind of device of flexure element test geomaterial small strain viscoelastic parameters:
Including test sample, receive flexure element, excitation flexure element, foam rods, signal generator, power amplifier, charge
Amplifier and oscillograph, test sample are placed in the plane by foam rods, and it is curved that the both ends of test sample are connected separately with reception
Qu Yuan and excitation flexure element, receive flexure element and the piezoelectric ceramic piece of flexure element are motivated to be inserted into test sample, receive curved
Qu Yuanjing charge amplifier is connect with oscillograph, excitation flexure element connect through power amplifier with oscillograph, power amplifier and
Signal generator connection.
To be inserted into the depth of test sample identical with the piezoelectric ceramic piece of excitation flexure element for the reception flexure element.
The test sample is in the form of a column, and Ratio of long radius to short radius is greater than 3.The draw ratio of column type test sample is answered larger to guarantee body
Wave in the sample can approximation regard one-dimensional propagation as.
The column test sample is propped by two foam rods, and two position of the fulcrum are respectively test sample both ends far from end
0.2 times of face bulk sample strong point to guarantee the minimum of peak value moment of flexure suffered by column test sample, and then reduces sample Stress non-homogeneity point
Influence of the cloth to test result.
Element of the flexure element as test Rock And Soil shear wave velocity develops existing ten several years, answering in soil test
With also comparative maturity.Nowadays, there is preferable popularization, without being merely present in Scientific Research in University Laboratory.Flexure element is surveyed
Try based on wave theory it is relatively complete, many years application also have preferable effect, be that current laboratory test is more reliable
Wave velocity testing element.
The main material of flexure element of the present invention is piezoelectric ceramics, and cubic deformation can be generated under the excitation of voltage.Excitation
Flexure element can both generate shearing wave under the excitation of voltage, can also generate compressional wave.In previous flexure element application process,
Near-field effect caused by compressional wave is often eliminated, in order that obtaining clearly shearing wave signal.But near field conversely speaking,
Effect also reflects the compression velocity of wave of sample material.The limitation of meta structure form by bending, the shearing wave energy generated are remote
Greater than compressional wave.Compressible wave is propagated fastly, is reached prior to shearing wave and is received flexure element, so in the pressure for receiving signal Small Amplitude
Contracting wave arriving signal is easy to differentiate.As for shearing wave, energy is higher by compressional wave an order of magnitude, the presence of compressional wave not shadow
Ring its differentiation for just reaching signal.If so, compression velocity of wave and the shearing of test material can be obtained by the analysis to signal is received
Velocity of wave.By perfect elastic body wave theory it is found that bulk wave velocity of wave is related with the Young's modulus, modulus of shearing, Poisson's ratio of material, together
When consider in three elastic parameters relation of equal quantity, it will be able to three equations of column solve three unknown quantitys.
Test method of the present invention need to first prepare column type geomaterial sample, select compared with big L/D ratio to guarantee that bulk wave exists
Approximate one-dimensional propagation in sample.The two sides of sample are inserted into the excitation end of flexure element and receiving end respectively.Occurred when test by signal
Device generates pulse voltage signal, makes that flexure element is motivated to motivate elastic body wave (shearing wave and compression in column type test sample
Wave), bulk wave is propagated along specimen length direction, is received flexure element by the other end and is received.Energy is higher simultaneously, decaying is slower cuts
It cuts wave and encounters free boundary back reflection in the column test sample other end, continue in sample internal communication.In experimentation as far as possible
Guarantee that sample is hanging, reduces the transmission of shearing wave on the contact surface, internal damping is enabled to become the main original for causing bulk wave to be decayed
Cause.Receiving end flexure element can obtain multiple shearing wave reflection signals in primary excitation, to these signal difference wave crests
Amplitude is analyzed, so that it may attenuation of the wave in communication process is obtained, thus according to the resistance of flight distance calculation material
Buddhist nun's ratio.
Beneficial effects of the present invention:
This invention simplifies the test methods of geomaterial parameter.
The meaning of the present invention laboratory apparatus expensive without more sets, is achieved with rock only with flexure element relevant apparatus
Native two sets of indexs of engineering material small strain viscoplasticity reduce testing cost.
During test, by the excitation and reception of sample bending two ends member, one group of fluctuation signal has just included ground work
The relevant information of journey material small strain viscoelastic parameters；Originally complicated test procedure is eliminated, strong operability saves test
Time；When signal is analyzed, the perfect elastic body wave theory of foundation is easily understood, explicit physical meaning.
The method of the present invention is tested based on bulk wave, is that material parameter is obtained in the case where geomaterial is lossless.So
Same sample can the retest under different control conditions, eliminate the possible uncontrollable influence of sample preparation again.Through trying
Verifying, using the reliability with higher of result acquired by the method for the present invention.
Detailed description of the invention
Fig. 1 is the method for the present invention test device schematic diagram；
Fig. 2 is embodiment high polymer column sample wave testing signal；
Fig. 3 is that the test of embodiment high polymer is preceding reaches shearing wave signal Fourier spectrum three times；
Fig. 4 is the relation curve of embodiment high polymer shearing wave attenuation coefficient and frequency.
In figure: 1, test sample；2, receive flexure element；3, motivate flexure element；4, piezoelectric ceramic piece；5, foam rods；6, letter
Number generator；7, power amplifier；8, charge amplifier；9, oscillograph；10, compressional wave first passage time point；11, shearing wave just reaches
Time point；12, shearing wave is reached for the first time；13, second of arrival shearing wave；14, third time reaches shearing wave；15, bulk wave swashs
Encourage time point.
Specific embodiment
The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.
This method is based on flexure element test device, obtains test material by the analysis to bulk wave velocity of wave and bulk wave decaying
Viscoplasticity index.
This method test device includes receiving flexure element 2, excitation flexure element 3, foam rods 5, signal generator 6, power to put
Big device 7, charge amplifier 8 and oscillograph 9, test need to prepare the biggish cylindrical sample of draw ratio, and with contact few as far as possible
Area is shelved in foam rods 5, and position of the fulcrum is that sample both ends are respectively retracted 0.2L.When test, sample one end flexure element is motivated
Pulse signal, the signal include compressional wave and shearing wave component, receive flexure element record by the other end after propagating in sample.
Contrast signal motivates receiving time difference to can get the velocity of wave of two kinds of bulk waves, to calculate the soil body by perfect elastic body wave theory
Elastic parameter.Meanwhile reflection occurs at styletable free boundary and continues to propagate for the shearing wave that energy is higher, decaying is slower, compares
The shearing wave successively reached can grasp the case where shearing wave is with range attenuation, estimate the damping ratio of sample material whereby.
Specifically, the concrete operations principle process of the method for the present invention is as follows:
Step 1: preparation is in the form of a column the column type geomaterial sample of a length of L, and the density p of test sample.Sample
Draw ratio should be greater than 3, with guarantee bulk wave in the sample can approximation regard one-dimensional propagation as.
Step 2: determining the system delay t of test circuit0, determine that flexure element receives the initial take-off direction of signal.
Step 3: as shown in Figure 1, causing the damping ratio being calculated inclined to prevent bulk wave from transmiting in communication process
Greatly, the test sample 1 being in the form of a column need to be placed in the plane by foam rods 5 when test, position of the fulcrum is the retraction of sample both ends
0.2L, L are the total length of column sample.The both ends of test sample 1, which are connected separately with, receives flexure element 2 and excitation flexure element 3, connects
It receives flexure element 2 and the piezoelectric ceramic piece 4 of flexure element 3 is motivated to be inserted into test sample 1, record each flexure element piezoelectric ceramics
Insertion depth l.
Step 4: circuit connection such as Fig. 1, signal generator generates pulse signal, after power amplifier, the signal point
For two-way: motivating flexure element 3 all the way, vibrate piezoelectric ceramics in the sample, while generating shearing wave and compressional wave；Another way connects
To oscillograph 9, pumping signal is recorded.The bulk wave that excitation flexure element 3 evokes is propagated along specimen length direction, is connect in the other end
It receives flexure element 2 to receive, is converted into electric signal.The higher shearing wave of energy is met styletable free boundary and can be reflected simultaneously, causes
Shearing wave carrys out back propagation in sample.
Step 5: the wave signal recording the excitation of transient state and successively reaching.The take-off time point of pumping signal is calculated as
T0, receive in signal, what is reached at first belongs to compressional wave, the first passage time point T using first voltage fluctuation as compressional wavep.It cuts
Wave energy is cut greater than compressional wave, so significantly increasing in section with voltage magnitude, with the initial take-off direction consistent first of flexure element
First passage time point T of a balance of voltage position as shearing waves.The system that the first passage time of bulk wave subtracts test device again is missed
Difference, as the actual propagation time in the sample of bulk wave consider further that propagation distance can calculate compressional wave in sample and propagate
Velocity of wave VpVelocity of wave V is propagated with shearing waves.Calculation formula is as follows:
Step 6: according to elastic wave prorogation theory it is found that there are following relationships between elastic parameter and bulk wave velocity of wave:
G=ρ Vs 2 (4)
G --- modulus of shearing；
E --- Young's modulus；
μ --- Poisson's ratio；
ρ --- density of material.
After obtaining bulk wave velocity of wave, the elastic parameter of test material can be calculated directly by formula 3~5.Step 7: due to swashing
In the pulse signal of hair, the energy of compressional wave is smaller, so the bulk wave for arriving again at reception flexure element after reflection is predominantly cut
Cut wave.Shearing wave approximation regards one-dimensional propagation as in sample, and communication process geonetrical attenuation can be ignored.And test when sample almost
Vacantly, bulk wave will not transmit, so the main reason for shearing wave attenuation is caused to be exactly the material of geomaterial sample
Damping.
When analysis, the first shearing wave that successively reaches after distinguishing reflection in the time-domain signal received, and will believe every time
Number take equal long durations by discrete Fourier transform method migration into frequency domain.Since in communication process, different frequency fluctuation
Attenuation it is different, so successively reaching the energy attenuation situation of each vibration frequency in shearing wave will be calculated by following formula
--- i-th reaches shearing wave signal amplitude corresponding to each frequency f in a frequency domain；
--- jth time reaches shearing wave signal amplitude corresponding to each frequency f in a frequency domain；
αf--- the corresponding attenuation coefficient fluctuated of each frequency f.
I, j indicates the ordinal number for successively reaching receiving end shearing wave.
Step 8: according to formula 6 can get different frequency corresponding to attenuation coefficient, corresponding relationship reflects in coordinate diagram
For frequency-attenuation coefficient curve, slope are as follows:
S is attenuation coefficient (αf) and slope of frequency (f) relation curve at main energy frequency range, Δ αfIt is shearing wave in master
The variable quantity of energy frequency range attenuation coefficient, Δ f are that the section of the main energy frequency range of shearing wave is long.
Step 9: in view of the damping of general geomaterial is smaller, damping ratio can be calculated by following formula:
In formula, δ is the damping ratio of geomaterial.
The embodiment of the present invention and its specific implementation process are as follows:
The present embodiment is by earth and rockfill dam core walling material (two-pack foamable polyurethane, hereinafter referred high polymer) as test pair
As carrying out the test of material small strain viscoelastic parameters.
Step 1: prepare a length of 15cm, diameter is the column type high polymer sample of 5cm, weighing, calculate the density of sample is
169kg/m3。
Step 2: by excitation, the direct contact of reception flexure element front end piezoelectric ceramic piece, by comparing excitation, receiving letter
Number, it determines that the system delay of flexure element test is 24 μ s, determines that the initial take-off direction of flexure element reception signal is downward.
Step 3: high polymer sample 1 being placed in the plane by foam rods 5, the both ends of test sample 1 are connected separately with
Flexure element 2 and excitation flexure element 3 are received, flexure element 2 is received and the piezoelectric ceramic piece 4 of flexure element 3 is motivated to be inserted into test examination
In sample 1, the insertion depth 1cm of each flexure element piezoelectric ceramics is recorded.
Step 4: such as Fig. 1 connection circuit, signal generator generates the sinusoidal impulse voltage of 10kHz, puts through power amplifier
After big, oscillograph is led to all the way, records the actuation duration；Another way leads to excitation flexure element, and flexure element is enabled to vibrate in the sample,
Motivate elastic body wave.Bulk wave approximate one-dimensional propagation in the sample, the higher shearing wave of energy can be reflected in styletable free boundary,
The fluctuation receiving end flexure element of sample receives in test process, voltage signal is converted into, and amplify through charge amplifier, by showing
Wave device record.
Step 5: as shown in Fig. 2, in figure, the voltage for receiving signal occurs the type signal that the present embodiment is tested at first
Fuctuation within a narrow range, the compressional wave that this is small by energy, velocity of wave is fast cause, and fuctuation within a narrow range beginning is compressional wave first passage time point 10；
Then, it receives signal and obvious fluctuation occurs, voltage magnitude increases.Because determining that the initial take-off direction of flexure element is downward before,
So obviously to fluctuate at section voltage first time decline as shearing wave first passage time point 11；Pumping signal is sinusoidal voltage pulse,
Its ski-jump is bulk wave actuation duration point 15.
Step 6: each calculating parameter value can be obtained from Fig. 2, and calculate and obtain bulk wave velocity of wave.Each time in the present embodiment
The reading of point and velocity of wave calculated result such as table 1.
High polymer material small strain viscoelastic parameters test result in 1 the present embodiment of table
Step 7: receiving signal back segment and be clearly present the shearing wave signal that several different times reach, use dotted line ellipse in Fig. 2
Circle goes out.According to the sequencing for fluctuating arrival in signal is received, can be classified as reaching shearing wave 12 for the first time, second
Shearing wave 13 is reached, and third time reaches shearing wave 14.
Step 8: the long durations 1.024ms analyses (totally 1024 sampled points) such as wave signal takes respectively are reached three times by preceding:
By time-domain signal by discrete Fourier transform method migration to frequency domain, as a result as shown in figure 3, the fundamental frequency of signal is 976Hz.It removes
There is peak value near 8000Hz frequency in the corresponding DC component of 0Hz frequency, three curves.Thus in the present embodiment,
The main energy frequency range of shearing wave signal is 6836Hz to 8789Hz.Then, shearing wave signal is reached before calculating according to the following formula three times
Between any two, the corresponding attenuation coefficient of each frequency
--- i-th reaches shearing wave signal amplitude corresponding to each frequency f in a frequency domain；
--- jth time reaches shearing wave signal amplitude corresponding to each frequency f in a frequency domain；
αf--- the corresponding attenuation coefficient fluctuated of each frequency f.
I, j indicates the shearing wave ordinal number for successively reaching receiving end flexure element.
Step 9: calculated result can be drawn in three curves in attenuation coefficient-frequency coordinate system, obtain at main energy frequency range
Slope S, as shown in Figure 4.The corresponding data point of main energy frequency is irised out with dashed rectangle in Fig. 4, three curves in frame
All there is similar slope, wherein Δ αfTake in dashed rectangle the corresponding decaying system of two frequencies of 8789Hz and 6836Hz on each curve
Several differences, length Δ f this example of main energy frequency section are 1953Hz.
It finally calculates and obtains damping ratio, wherein previously having measured the V of shear wave velocitysTake 253m/s.Calculated result such as the following table 2 institute
Show:
2 high polymer damping ratio test result of table
By embodiment as it can be seen that the method for the present invention device is simple and effective, merely with flexure element and corresponding test equipment, only pass through
The excitation and reception of signal, so that it may obtain geomaterial small strain viscoelastic parameters.Explicit physical meaning passes through reason
Think the wave theory and one-dimensional wave theory of elastomer, it is established that wave signal and geomaterial small strain viscoelastic parameters
Between relationship, obvious technical effects are prominent, are applicable to the lossless inspection of a variety of geomaterial small strain viscoelastic parameters
It surveys, has a wide range of application.
Claims (4)
1. a kind of method of flexure element test geomaterial small strain viscoelastic parameters, it is characterized in that the following steps are included:
1) column type geomaterial sample is prepared, obtains its density of material by weighing, surveying volume；
2) excitation flexure element and reception flexure element are connected to the two of cylindrical sample by fixed column type geomaterial sample
End, the piezoelectric ceramics of two flexure elements are inserted into same depth in column type geomaterial sample；
3) signal generator generates pulse voltage signal as pumping signal, is divided into two-way, wherein putting all the way through power amplifier
It is sent to oscillograph recording after big, another way leads to excitation flexure element, motivates elasticity in column type geomaterial sample
Bulk wave, the fluctuation that reflection is generated in sample are received flexure element and successively receive, be converted into voltage signal and amplify through charge amplifier
Afterwards as signal is received, it is sent to oscillograph recording；
4) analysis receives signal, calculates and obtains geomaterial small strain viscoelastic parameters；
The elastic parameter is specifically calculated in the following ways and obtained: signal, which is propagated, in analysis cylindrical sample successively reaches shearing
The attenuation of wave is calculated using the following equation the damping ratio for obtaining cylindrical sample in conjunction with the propagation distance of shearing wave:
Wherein, VsVelocity of wave propagation is sheared for geomaterial, S indicates attenuation coefficient αfRelation curve with frequency f is in main energy
Measure the slope at frequency range；
The attenuation coefficient αfIt is calculated using the following equation with the slope S of the relation curve of frequency f at main energy frequency range:
Wherein, Δ αfIt is shearing wave in the variable quantity of main energy frequency range attenuation coefficient, Δ f is the section of the main energy frequency range of shearing wave
It is long；
Attenuation coefficient α corresponding to different frequency is obtained using following formulaf: it is first distinguished from the time-domain signal received anti-
The shearing wave successively reached afterwards is penetrated, and takes equal long durations to pass through discrete Fourier transform method migration to frequency domain each signal
In, then the successive energy attenuation situation for reaching each vibration frequency in shearing wave calculated by following formula:
--- i-th reaches shearing wave signal amplitude corresponding to each frequency f in a frequency domain；
--- jth time reaches shearing wave signal amplitude corresponding to each frequency f in a frequency domain；
αf--- the corresponding attenuation coefficient fluctuated of each frequency f；
I, j indicates that the ordinal number for successively reaching receiving end shearing wave, L are the length of cylindrical sample.
2. a kind of method of flexure element test geomaterial small strain viscoelastic parameters according to claim 1,
Be characterized in: the elastic parameter is specifically calculated in the following ways and is obtained: just reaching signal according to pumping signal and elastic body wave
Between time difference, obtain geomaterial sample in signal propagate bulk wave velocity of wave, then according to perfect elastic body fluctuation reason
By solving to obtain the elastic parameter of the sample material by following formula, elastic parameter includes Young's modulus, modulus of shearing and pool
Loose ratio:
G=ρ Vs 2
Wherein, G indicates modulus of shearing, and E indicates Young's modulus, and μ indicates Poisson's ratio, and ρ indicates density of material, VpFor geotechnical engineering material
Material compression velocity of wave propagation, VsVelocity of wave propagation is sheared for geomaterial.
3. a kind of method of flexure element test geomaterial small strain viscoelastic parameters according to claim 2,
Be characterized in: the geomaterial compresses velocity of wave propagation VpVelocity of wave propagation V is sheared with geomaterialsIt is respectively adopted
Following formula calculates:
Wherein, T0For the take-off time point of pumping signal, TpFor the first passage time point of compressional wave, TsFor the first passage time of shearing wave
Point, t0The system delay of circuit is tested between excitation flexure element and reception flexure element, L is the length of cylindrical sample, and l is bending
The insertion depth of first piezoelectric ceramics.
4. a kind of method of flexure element test geomaterial small strain viscoelastic parameters according to claim 1,
It is characterized in: keeps the cylindrical sample hanging as far as possible when test.
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| CN109813807A (en) * | 2018-12-19 | 2019-05-28 | 国网江苏省电力有限公司经济技术研究院 | A kind of device of handheld piezoelectric element test rock-soil material viscoelastic parameters |
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| CN101413823A (en) * | 2008-05-12 | 2009-04-22 | 浙江大学 | Portable piezoelectric ceramic bending element soil body shear wave speed test device |
| CN102288678A (en) * | 2011-05-13 | 2011-12-21 | 浙江大学 | Method for evaluating soft soil disturbance degree by using shear wave velocity |
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