CN218726933U - Ultrasonic rock longitudinal and transverse wave velocity measuring device based on coded excitation - Google Patents
Ultrasonic rock longitudinal and transverse wave velocity measuring device based on coded excitation Download PDFInfo
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Abstract
The utility model discloses an supersound rock vertical and horizontal wave speed measuring device based on coding excitation, including host system, code modulation module, emission module, the integrative transmitting probe of vertical and horizontal wave, the integrative receiving probe of vertical and horizontal wave, data acquisition module and data processing module. The measuring device disclosed by the invention applies the coding excitation technology to the measurement of the longitudinal and transverse wave sound velocity of the rock, and can improve the signal-to-noise ratio of an observed waveform under the condition of not losing resolution; different excitation voltages can be selected for rocks with different lithology, the amplitude of the transmitted signal is improved in a high-voltage excitation mode, and the signal-to-noise ratio of the observed waveform is further enhanced; adopt the longitudinal and transverse wave integral type ultrasonic probe, can measure the longitudinal wave of rock, transverse wave speed under same environment, need not to relapse dismouting probe, avoid traditional equipment to disturb because of the environmental factor that the change probe brought, improved measurement of efficiency simultaneously.
Description
Technical Field
The utility model belongs to ultrasonic wave rock measurement field, in particular to ultrasonic rock vertical and horizontal wave speed measuring device based on coding excitation in this field for the vertical and horizontal wave speed ultrasonic testing of rock test piece.
Background
The acoustic properties (elastic modulus, sound velocity, attenuation coefficient, etc.) of rock are important parameters of rock materials, and have great correlation with the internal structure of rock and rock strength. In a laboratory, the relation between the rock structure and the elastic parameters is generally researched by an ultrasonic transmission method, namely, ultrasonic pulses are transmitted at one end of a rock test piece, a transmission signal is received at the other end by using a receiving transducer, and then the recorded waveform data is analyzed to research the change of the acoustic parameters. However, in practical tests, due to the bandwidth limitation of the transducer, background noise interference, poor coupling, rock frequency attenuation and the like, the signal-to-noise ratio of the received signal is low, and the ultrasonic penetration capability is insufficient, so that the difficulty in information identification is caused.
The solution to the above problem is generally to increase the amplitude of the transmitted signal and the signal-to-noise ratio of the desired signal. Most ultrasonic rock sound velocity measurement devices achieve the increase of the amplitude of the transmitted signal by increasing the excitation voltage. Considering that the limit voltage value borne by the ultrasonic transducer and the increase of the excitation voltage can increase the design difficulty of the hardware driving circuit, the excitation voltage of the current measuring device is mostly concentrated between 200V and 400V.
The coding excitation technology is a method capable of improving the signal-to-noise ratio of effective signals, and is widely applied to the fields of medical ultrasonic imaging, radar systems, nondestructive testing and the like. The method can obtain the same signal-to-noise ratio and resolution ratio as high-power single-pulse signals by using a low-power signal generator to transmit coded signals. In consideration of the complexity of the rock ultrasonic detection problem, the introduction of the coded excitation technology into the rock ultrasonic detection field has many specific problems, such as rock frequency-dependent attenuation problem, nonlinear propagation problem of waves caused by complex structures inside rocks, and the like, which affect the compression performance of the coded excitation technology. Although some researchers have carried out related work to research and study the propagation of the coded signal in the rock and the pulse-pressing mechanism thereof, at present, no ultrasonic rock sound velocity measuring device applies the coded excitation technology to the actual rock acoustic characteristic measuring process.
SUMMERY OF THE UTILITY MODEL
The utility model aims to solve the technical problem that just can obtain higher SNR in the rock ultrasonic measurement of different conditions, improve rock measurement accuracy, start from improving emission signal amplitude and effective signal SNR two aspects, provide an ultrasonic rock vertical and horizontal wave speed measuring device and method based on coding excitation for laboratory rock mass test piece ultrasonic measurement.
The utility model adopts the following technical scheme:
in an ultrasonic rock longitudinal and transverse wave velocity measuring device based on coded excitation, the improvement is that: the device comprises a main control module, a code modulation module, a transmitting module, a longitudinal and transverse wave integrated transmitting probe, a longitudinal and transverse wave integrated receiving probe, a data acquisition module and a data processing module; the main control module is electrically connected with the code modulation module, the transmitting module, the data acquisition module and the data processing module, and sends a set code to the code modulation module according to a user instruction sent by the data processing module, and sets an excitation voltage, a longitudinal wave channel and a transverse wave channel of the transmitting module; the code modulation module performs phase modulation on the set code sent by the main control module to generate a phase code signal and sends the phase code signal to the transmitting module; the transmitting module generates positive and negative high-voltage excitation signals according to the phase coding signals, and excites the longitudinal and transverse wave integrated transmitting probe from a set longitudinal wave channel or transverse wave channel by using the positive and negative high-voltage excitation signals, so that the longitudinal and transverse wave integrated transmitting probe emits ultrasonic mechanical waves to the rock, the longitudinal and transverse wave integrated receiving probe receives the ultrasonic mechanical waves transmitted through the rock, converts the ultrasonic mechanical waves into transmission wave electric signals and transmits the transmission wave electric signals to the data acquisition module, and the data acquisition module performs pre-amplification, gain adjustment, filtering and A/D conversion on the received transmission wave electric signals to obtain transmission wave original waveforms which are uploaded to the data processing module through the main control module.
Furthermore, the master control module adopts ZYNQ-7020 as a master control chip.
Further, the code modulation module adopts spartan6 as a main chip.
Further, the excitation voltage of the transmitting module reaches 800V at most.
Furthermore, the transmitting module comprises a high-voltage MOS combined tube, a relay and a DC adjustable high-voltage module; the high-voltage MOS combined tube comprises an N-MOS tube, a P-MOS tube and a driving chip EL7222, the transmitting module converts a phase coding signal into a control signal of the N-MOS tube and a control signal of the P-MOS tube, the N-MOS tube transmits a positive high-voltage excitation signal when being conducted, and the P-MOS tube transmits a negative high-voltage excitation signal when being conducted; the main control module controls the transmitting module to switch a longitudinal wave channel and a transverse wave channel through a relay; the main control module sets the excitation voltage of the transmitting module through the DC adjustable high-voltage module.
Furthermore, the data acquisition module adopts a 14-bit high-speed ADC, and the sampling rate reaches 65MPS.
In a method of measuring using the above measuring device, the improvement comprising the steps of:
and 3, performing phase modulation on the set code sent by the main control module by using a code modulation module to generate a phase code signal s (t), and sending the phase code signal s (t) to a transmitting module, wherein a phase modulation function is expressed as follows:
in the above-mentioned formula, the compound has the following structure,
represents linear convolution, delta () represents square wave, T represents time, T represents termination time, T is more than or equal to 0 and less than or equal to T, p (T) is a sub-pulse function, c is coding, and N is coding length;
step 6, the data acquisition module performs pre-amplification, gain adjustment, filtering and A/D conversion on the received transmission wave electric signal to obtain a transmission wave original waveform r (t) and sends the transmission wave original waveform r (t) to the main control module;
and 7, uploading the original transmitted wave waveform r (t) to a data processing module by a main control module, performing pulse compression by the data processing module to obtain a pulse compression waveform h (t), maximizing the signal-to-noise ratio by the pulse compression through a matched filter, and expressing the pulse response function of the matched filter as follows:
h(t)＝w·s(τ d -t) (2)
in the above formula: w is a gain factor, τ d For the duration of the excitation signal, s (τ) d -t) represents τ d -a phase encoded signal at time t;
and 8, after the data processing module acquires the pulse compression waveform h (t), automatically picking up the first arrival of the pulse compression waveform by using a Bayes information criterion, and calculating the wave velocity of the measured rock according to the first arrival, wherein the calculation formula of the Bayes information criterion is as follows:
BIC(q 0 )＝q 0 ln(var{X(1,q 0 )})+(M-q 0 -1)ln(var{X(q 0 +1,M)})-q 0 ln(M) (3)
in the above formula: BIC represents Bayesian information value of observed waveform data, the minimum point is the accurate position of first arrival, X represents observed waveform data, M is the number of sampling points of observed waveform, q 0 The first arrival position is represented and var represents the variance.
The utility model has the advantages that:
the utility model discloses a measuring device, which applies the coding excitation technology in the rock longitudinal and transverse wave sound velocity measurement, can improve the signal-to-noise ratio of the observation waveform without losing resolution; different excitation voltages can be selected for rocks with different lithology, the amplitude of the transmitted signal is improved in a high-voltage excitation mode, and the signal-to-noise ratio of the observed waveform is further enhanced; adopt the longitudinal and transverse wave integral type ultrasonic probe, can measure the longitudinal wave of rock, transverse wave speed under same environment, need not to relapse dismouting probe, avoid traditional equipment to disturb because of the environmental factor that the change probe brought, improved measurement of efficiency simultaneously.
The utility model discloses a measuring method improves the SNR of observing the waveform and to the measurement accuracy of rock longitudinal and transverse wave speed through adopting phase modulation and pulse compression signal reception technique.
Drawings
FIG. 1 is a block diagram of the measurement device disclosed in the present invention;
fig. 2 is a schematic circuit diagram of a transmitting module in the measuring device disclosed in the present invention;
FIG. 3 is a schematic flow diagram of a measurement method disclosed herein;
FIG. 4 is a graph comparing observed waveforms for coded excitation and single pulse excitation.
Reference numerals: the device comprises a main control module, a coding modulation module 2, a transmitting module 3, a longitudinal and transverse wave integrated transmitting probe 4, a longitudinal and transverse wave integrated receiving probe 5, a data acquisition module 6 and a data processing module 7.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in further detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
As shown in fig. 1, the measuring device includes a main control module 1, a code modulation module 2, a transmitting module 3, a longitudinal and transverse wave integrated transmitting probe 4, a longitudinal and transverse wave integrated receiving probe 5, a data acquisition module 6 and a data processing module 7; by adopting the longitudinal and transverse wave integrated probe, the longitudinal wave sound velocity and the transverse wave sound velocity can be measured successively after the rock test piece is successfully installed, the longitudinal wave and transverse wave sound velocity can be measured in the same experimental environment, the interference caused by the introduction of the external environment due to the repeated replacement of the measuring probe is avoided, and the measuring efficiency is improved while the accuracy of the rock longitudinal and transverse wave velocity measurement is enhanced.
The main control module is electrically connected with the code modulation module, the transmitting module, the data acquisition module and the data processing module, and sends a set code to the code modulation module according to a user instruction sent by the data processing module, and sets an excitation voltage, a longitudinal wave channel and a transverse wave channel of the transmitting module; the code modulation module performs phase modulation on the set code sent by the main control module, generates a phase code signal and sends the phase code signal to the transmitting module; the transmitting module generates positive and negative high-voltage excitation signals according to the phase coding signals, and excites the longitudinal and transverse wave integrated transmitting probe from a set longitudinal wave channel or transverse wave channel by using the positive and negative high-voltage excitation signals, so that the longitudinal and transverse wave integrated transmitting probe emits ultrasonic mechanical waves to the rock, the longitudinal and transverse wave integrated receiving probe receives the ultrasonic mechanical waves transmitted through the rock, converts the ultrasonic mechanical waves into transmission wave electric signals and transmits the transmission wave electric signals to the data acquisition module, and the data acquisition module performs pre-amplification, gain adjustment, filtering and A/D conversion on the received transmission wave electric signals to obtain transmission wave original waveforms which are uploaded to the data processing module through the main control module.
The main control module adopts ZYNQ-7020 as a main control chip and is responsible for the work flow control, the instruction receiving and execution, the excitation voltage control, the transmission wave data acquisition and uploading and the like.
The code modulation module adopts spartan6 as a main chip and is responsible for carrying out phase modulation on binary codes to generate phase coding signals, so that the problem of low efficiency caused by direct code sending is avoided, and frequency spectrum control can be better carried out.
The user can select different codes and excitation voltages according to the requirement, the maximum excitation voltage of the transmitting module reaches 800V, the problems that common ultrasonic equipment is low in excitation voltage and cannot continuously excite and transmit the codes are effectively solved, and transmitting signals with high amplitude can be generated.
The longitudinal wave and transverse wave integrated probe is responsible for generating and receiving ultrasonic signals and can respectively generate and receive longitudinal wave signals and transverse wave signals in the same measuring environment.
As shown in fig. 2, the transmitting module includes a high-voltage MOS combination tube, a relay, and a DC adjustable high-voltage module; the high-voltage MOS combined tube comprises an N-MOS tube Q1, a P-MOS tube Q2 and a driving chip EL7222, and can continuously send positive and negative high-voltage excitation signals, a transmitting module converts phase coding signals into control signals SIGL + and SIGL-of the N-MOS tube and the P-MOS tube, the N-MOS tube is connected with positive voltage, the P-MOS tube is connected with negative voltage, when the code is 1, a positive pulse signal SIGL + triggers the N-MOS tube to be conducted and transmits the positive high-voltage excitation signals, and when the code is 0, a negative pulse signal SIGL-triggers the P-MOS tube to be conducted and transmits the negative high-voltage excitation signals. The main control module controls the transmitting module to switch a longitudinal wave channel and a transverse wave channel through a relay K1;
the excitation voltage is provided by a DC adjustable high-voltage module, the high-voltage module is controlled by voltage, and the main control module sets the excitation voltage of the transmitting module through the DC adjustable high-voltage module.
The data acquisition module is responsible for processing and acquiring the electric signal of the transmission wave, adopts a 14-bit high-speed ADC, has a sampling rate of 65MPS and can realize accurate acquisition of the electric signal of the transmission wave.
The data processing module is an upper computer module and is responsible for receiving the original waveform of the transmitted wave sent by the main control module and performing pulse compression processing to obtain a pulse compression waveform, and performing initial pickup of the sound wave and calculation of the sound velocity.
The embodiment also discloses a measuring method, which uses the measuring device and comprises the following steps:
and 3, performing phase modulation on the set code sent by the main control module by using a code modulation module to generate a phase code signal s (t), and sending the phase code signal s (t) to a transmitting module, wherein a phase modulation function is expressed as follows:
in the above formula, the first and second carbon atoms are,
representing a linear convolution, δ () representing a square wave, T representing time, T representing terminationAt the moment, T is more than or equal to 0 and less than or equal to T, p (T) is a sub-pulse function, c is coding, and N is coding length;
step 6, the data acquisition module performs pre-amplification, gain adjustment, filtering and A/D conversion on the received transmission wave electric signal to obtain a transmission wave original waveform r (t) and sends the transmission wave original waveform r (t) to the main control module;
h(t)＝w·s(τ d -t) (2)
in the above formula: w is a gain factor, τ d The duration of the excitation signal, s (τ) d -t) represents τ d -a phase encoded signal at time t;
the electric signal of the transmitted wave is pre-amplified and gain-adjusted, and then the data processing module performs pulse compression on the original waveform of the transmitted wave, so that the signal-to-noise ratio of the signal can be greatly improved, and a more accurate first arrival of the transmitted wave is extracted.
And 8, after the data processing module acquires the pulse compression waveform h (t), automatically picking up the first arrival of the pulse compression waveform by using a Bayesian information criterion, and calculating the wave velocity of the detected rock according to the first arrival, wherein the calculation formula of the Bayesian information criterion is as follows:
BIC(q 0 )＝q 0 ln(var{X(1,q 0 )})+(M-q 0 -1)ln(var{X(q 0 +1,M)})-q 0 ln(M) (3)
in the above formula: BIC represents Bayesian information value of observed waveform data, the minimum point is the accurate position of first arrival, X represents observed waveform data, M is the number of sampling points of observed waveform, q 0 The first arrival position is represented and var represents the variance.
Specifically, taking the example of detecting red sandstone with a length of 50mm, the whole measurement flow is shown in fig. 3. First, a rock specimen is placed on a measuring device and an appropriate excitation voltage is selected according to the lithology of the rock. And secondly, the transmitting module transmits positive and negative high-voltage excitation signals to the transmitting probe according to preset excitation voltage and coding information, the excitation signals penetrate through the rock test piece and are received by the receiving probe at the other end, and the original waveform of rock measurement is obtained. And then, the data processing module performs pulse compression on the acquired original waveform to obtain a pulse compressed waveform. And finally, automatically picking up the first arrival of the pulse compression waveform by using a Bayesian information criterion, and calculating the wave velocity of the tested rock test piece according to the first arrival.
Fig. 4 shows a comparison graph of observed waveforms of a single pulse excitation and a coding excitation in the red sandstone sound velocity measurement. As can be seen from the figure, the signal-to-noise ratio of the observed waveform based on the coded excitation technology is higher, and the first arrival of the ultrasonic wave is easier to be accurately picked up.
Claims (6)
1. An ultrasonic rock longitudinal and transverse wave velocity measuring device based on coded excitation is characterized in that: the device comprises a main control module, a code modulation module, a transmitting module, a longitudinal and transverse wave integrated transmitting probe, a longitudinal and transverse wave integrated receiving probe, a data acquisition module and a data processing module; the main control module is electrically connected with the code modulation module, the transmitting module, the data acquisition module and the data processing module, and sends a set code to the code modulation module according to a user instruction sent by the data processing module, and sets an excitation voltage, a longitudinal wave channel and a transverse wave channel of the transmitting module; the code modulation module performs phase modulation on the set code sent by the main control module, generates a phase code signal and sends the phase code signal to the transmitting module; the transmitting module generates positive and negative high-voltage excitation signals according to the phase coding signals, and excites the longitudinal and transverse wave integrated transmitting probe from a set longitudinal wave channel or transverse wave channel by using the positive and negative high-voltage excitation signals, so that the longitudinal and transverse wave integrated transmitting probe emits ultrasonic mechanical waves to the rock, the longitudinal and transverse wave integrated receiving probe receives the ultrasonic mechanical waves transmitted through the rock, converts the ultrasonic mechanical waves into transmission wave electric signals and transmits the transmission wave electric signals to the data acquisition module, and the data acquisition module performs pre-amplification, gain adjustment, filtering and A/D conversion on the received transmission wave electric signals to obtain transmission wave original waveforms which are uploaded to the data processing module through the main control module.
2. The ultrasonic rock longitudinal and transverse wave velocity measurement device based on coded excitation according to claim 1, characterized in that: the main control module adopts ZYNQ-7020 as a main control chip.
3. The ultrasonic rock longitudinal and transverse wave velocity measurement device based on coded excitation according to claim 1, characterized in that: the encoding modulation module adopts spartan6 as a main chip.
4. The ultrasonic rock longitudinal and transverse wave velocity measurement device based on coded excitation according to claim 1, characterized in that: the excitation voltage of the transmitting module reaches 800V at most.
5. The ultrasonic rock longitudinal and transverse wave velocity measurement device based on coded excitation according to claim 1, characterized in that: the transmitting module comprises a high-voltage MOS combined tube, a relay and a DC adjustable high-voltage module; the high-voltage MOS combined tube comprises an N-MOS tube, a P-MOS tube and a driving chip EL7222, the transmitting module converts a phase coding signal into a control signal of the N-MOS tube and a control signal of the P-MOS tube, the N-MOS tube transmits a positive high-voltage excitation signal when being conducted, and the P-MOS tube transmits a negative high-voltage excitation signal when being conducted; the main control module controls the transmitting module to switch a longitudinal wave channel and a transverse wave channel through a relay; the main control module sets the excitation voltage of the transmitting module through the DC adjustable high-voltage module.
6. The ultrasonic rock longitudinal and transverse wave velocity measurement device based on coded excitation according to claim 1, characterized in that: the data acquisition module adopts a 14-bit high-speed ADC, and the sampling rate reaches 65MPS.
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