CN101718579A - Method and system for measuring shear wave velocity of rock soil - Google Patents
Method and system for measuring shear wave velocity of rock soil Download PDFInfo
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- CN101718579A CN101718579A CN200910259842A CN200910259842A CN101718579A CN 101718579 A CN101718579 A CN 101718579A CN 200910259842 A CN200910259842 A CN 200910259842A CN 200910259842 A CN200910259842 A CN 200910259842A CN 101718579 A CN101718579 A CN 101718579A
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Abstract
The invention discloses a method and a system for measuring the shear wave velocity of rock soil. The method comprises that: firstly, a vibration source generates shear waves of which frequency is f1 at a time t0; a counter is triggered to begin counting at the time t0+tc, wherein the frequency of the trigger pulse of the counter is f2 and tc is a preset triggered counting delay; a detection signal which is output by a detection probe at a position n in a well hole is subjected to anti-interference processing to obtain square waves which are input to a shear wave receiving and processing circuit and have the frequency f1, wherein n is not less than 0; the counter stops counting at the time t1(n) when the shear wave receiving and processing circuit receives the square waves; and the comprehensive shear wave velocity of a travel route between the position n and the vibration source is calculated through the following formula. The method and the system of the invention can effectively improve the measurement accuracy of the shear wave velocity of the rock soil.
Description
Technical field
The present invention relates to a kind of measuring method and measuring system of ground kinetic parameter, relate in particular to a kind of system of measuring the method for shear wave velocity of rock soil and can realizing this method.
Background technology
Measuring the rock-soil layer shear wave velocity is one of important means of determining the moving parameter of tested ground, fields such as it is widely used in, and the earthquake peace is commented, construction work design and planning.Conventional measuring method all is to produce a unknown shearing wave (frequency, phase place and amplitude the unknown) by transient excitation, and the first motion of finding out acceptance point with artificial naked eyes on wave recording calculates the velocity of propagation of shearing wave in this rock stratum with the difference in the vibration source exciting moment constantly then.This measuring method is owing to need the artificial identification that participates in, and makes that the signal antijamming capability is relatively poor because frequency acceptance band is too wide, so its measuring error is bigger, generally about 15%-25%.In addition, in order to improve signal to noise ratio (S/N ratio), in most cases must be with artificial method exciting, the normal mode that adopts is hammering, has so just increased the workload of measuring process greatly, thereby has reduced efficiency of measurement.
Summary of the invention
One object of the present invention is to solve the low problem of present shear wave velocity of rock soil measuring accuracy, and a kind of new method of measuring shear wave velocity of rock soil is provided.
The technical solution adopted in the present invention is: a kind of method of measuring shear wave velocity of rock soil, and at first, producing frequency by vibration source at moment t0 is the shearing wave of f1; Begin counting at moment t0+tc flip-flop number, the frequency of the trigger pulse of described counter is f2, and wherein, tc is the time-delay of preset trigger counting; The detection signal that comprises described shearing wave that will be positioned at the demodulation probe output at n place, wellhole position carries out anti-interference process, and the output frequency that obtains inputing to the shearing wave receiving processing circuit is the square wave of f1, wherein, and n 〉=0; Described counter stops counting when the shearing wave receiving processing circuit receives the moment t1 (n) of described square wave;
The comprehensive shear wave velocity of stroke at n place, described vibration source in-position
Computing formula as follows, wherein, the unit of described time is ms, the unit of described frequency is MHz:
Wherein, D (n) is in the described demodulation probe at position n place and the air line distance between the vibration source; N (n) is described counter in the count value of moment t0+tc during the t1 (n) constantly.
Preferably, the process that described vibration source produces shearing wave is as follows, frequency is that the dutycycle of f0 is that 50% original square wave carries out frequency division through frequency divider and obtains the basic square wave that frequency is f1, it is the sine wave of f1 that described basic square wave amplifies back formation frequency through shaping, and described sine wave makes super magnetic horn export described shearing wave at moment t0 under the effect of switching tube.
Preferably, described demodulation probe is under the effect of joining humorous electric capacity, make its resonance frequency also be f1, the process of the anti-interference process of described detection signal is as follows, and the precipitous described square wave in lower edge was gone up in formation after described detection signal amplified and amplify shaping through preposition amplification, frequency-selecting successively.
Another object of the present invention is to provide a kind of system that can realize the measurement shear wave velocity of rock soil of said method.
The technical solution adopted in the present invention is: a kind of system of measuring shear wave velocity of rock soil comprises vibration source, receives processing unit, identification circuit and shearing wave receiving processing circuit;
Described vibration source comprises square-wave generator, and output frequency is that the dutycycle of f0 is 50% original square wave; Frequency divider carries out frequency division to described original square wave and handles, and obtaining frequency is the basic square wave of f1; Shaping and power amplification unit carry out the shaping processing and amplifying to described basic square wave, obtain the sine wave that frequency is f1; And, super magnetic horn, being connected with the described super magnetic horn of control between described super magnetic horn and described shaping and the power amplification unit is the switching tube of the shearing wave of f1 at moment t0 output frequency;
Described reception processing unit comprises demodulation probe, and described demodulation probe is joined and had that to make its resonance frequency be humorous electric capacity of joining of f1, and described demodulation probe is used to receive the detection signal that comprises described shearing wave; It is that the square wave of f1 is to described shearing wave receiving processing circuit that described reception processing unit is used for output frequency;
Described identification circuit comprises pulse producer, and output frequency is the trigger pulse of f2; Counter is used for counting under the effect of trigger pulse; Computing unit is used for computing counter at the count value N (n) of moment t0+tc during the t1 (n) constantly, and wherein, described shearing wave receiving processing circuit received the moment of described square wave, n 〉=0 when described moment t1 (n) was positioned at n place, position for described demodulation probe; Described computing unit is controlled the described sine wave of described switching tube conducting at moment t0, and wherein, described tc is the time-delay of computing unit preset trigger counting; Counting control unit, described counting control unit begin counting in moment t0+tc flip-flop number under the control of computing unit, stop rolling counters forward in moment t1 (n) under the control of described shearing wave receiving processing circuit.
Preferably, described reception processing unit also comprises pre-amplification circuit, is used for described detection signal is carried out preposition processing and amplifying, obtains preamplification signal; Selective frequency amplifier circuit is used for described preamplification signal is carried out the frequency-selecting processing and amplifying, and obtaining frequency is the frequency-selecting amplifying signal of f1; Shaping amplification circuit is used for described frequency-selecting amplifying signal is carried out final shaping processing and amplifying, exports described shearing wave.
Preferably, described demodulation probe comprises a plurality of wave detectors that are positioned on the different directions.
Preferably, described shearing wave receiving processing circuit comprise one be controlled by described computing unit often open flip-flop number switch and a normally closed termination counter switch that is controlled by described shearing wave receiving processing circuit.
Beneficial effect of the present invention is: the method for measurement shear wave velocity of rock soil of the present invention has adopted the generator of controlled known vibration source (frequency, phase place and amplitude are known) as shearing wave, and this gives the automatic identification of signal and improves measuring accuracy and created condition precedent; In addition, this method has adopted advanced signal measurement technique and measuring element simultaneously, thereby has realized shear wave velocity of rock soil is carried out high-acruracy survey, and measuring error is between 1% one 3%, and also improved efficiency of measurement, the test duration of 50 meters dark wellholes generally only needs 10 minutes.
Description of drawings
Fig. 1 is the schematic diagram of vibration source of the present invention;
Fig. 2 is the schematic diagram of reception processing unit of the present invention;
Fig. 3 is the schematic diagram of identification circuit of the present invention;
Fig. 4 is the principle schematic of the method for measurement shear wave velocity of rock soil of the present invention.
Embodiment
Now in conjunction with the accompanying drawings the method and system of measurement shear wave velocity of rock soil of the present invention are described in detail.
Shown in Fig. 1,2 and 3, the system of described measurement shear wave velocity of rock soil comprises vibration source 10, receives processing unit 20, identification circuit 30 and shearing wave receiving processing circuit 40.
Described vibration source comprises square-wave generator, frequency divider 102, shaping amplifying unit 103 and super magnetic horn 105.Described square-wave generator comprises crystal oscillator 101 and CMOS phase inverter, and the dutycycle that this square-wave generator output frequency is f0 is 50% original square wave.102 pairs of original square waves of described frequency divider carry out frequency division to be handled, and obtaining frequency is the basic square wave of f1, and in order to reduce the decay of shearing wave in ground and the interference of neighbourhood noise, the numerical value of f1 is preferably 300～500Hz, and concrete numerical value should not elected the integral multiple of 50Hz as.Because will promote super magnetic horn 105 needs certain power, therefore, carry out the shaping processing and amplifying by described shaping and 103 pairs of described basic square waves of power amplification unit, obtain frequency and be the sine wave of single f1, and output power is adjustable between 100w～1000w usually.Being connected with the described super magnetic horn 105 of control between super magnetic horn 105 and described shaping and the power amplification unit 103 is the switching tube 104 of the shearing wave of f1 at moment t0 output frequency.
Described reception processing unit 20 comprises demodulation probe 201, pre-amplification circuit 203, selective frequency amplifier circuit 204 and shaping amplification circuit 205.In this area, adopt wave detector as detection device usually, determine because the direction of wave detector in wellhole is difficult, therefore, in order to guarantee that demodulation probe 201 can detect enough big vibration signal, in the present embodiment, demodulation probe 201 is preferably and comprises a plurality ofly, is generally three, is positioned at the wave detector on the different directions; Described demodulation probe 201 is joined and is had that to make its resonance frequency be humorous electric capacity of joining of f1, can improve selectivity and the sensitivity that signal detects greatly like this, has promptly effectively improved the signal to noise ratio (S/N ratio) of the detection signal of demodulation probe 201 outputs.Described pre-amplification circuit 203 is used for described detection signal is carried out preposition processing and amplifying, obtains preamplification signal, and the gain amplifier of described pre-amplification circuit 203 can be selected between 20～100.Described selective frequency amplifier circuit 204 is used for described preamplification signal is carried out the frequency-selecting processing and amplifying, obtaining frequency is the frequency-selecting amplifying signal of f1, utilize the single characteristics of frequency f 1 of useful signal, present embodiment can amplify useful signal by the arrowband selective frequency amplifier circuit of high quality factor, and effectively curbs the outer undesired signal of band.Described shaping amplification circuit 205 is used for described frequency-selecting amplifying signal is carried out final shaping processing and amplifying, and the precipitous square wave in lower edge is to shearing wave receiving processing circuit 40 shown in Figure 4 in the output.
Described identification circuit 30 comprises pulse producer 301, counting control unit 302, counter 303 and computing unit 304.The frequency of described pulse producer output continous-stable is the trigger pulse of f2, and this trigger pulse is as the weights and measures of a standard.Counter 303 is used for counting under the effect of trigger pulse, for the resolution that improves time difference identification and the precision of record, frequency configuration with trigger pulse in the present embodiment is 20MHz, correspondingly, must improve the frequency of counter 303, adopt high speed binary counting chip in the present embodiment, here the chip of Cai Yonging is that cutoff frequency is 80MHz, model is 12 binary counting chips of 74HC4040, in addition, improve registration accuracy, must increase the figure place of counter 303, formed 24 scale-of-two high-speed counters by two 74HC4040 chips here.Described counting control unit 302 begins counting in moment t0+tc flip-flop number 303 under the control of computing unit 302, and stops counter 303 countings in moment t1 (n) under the control of described shearing wave receiving processing circuit 40; Wherein, described moment t1 (n) receives the moment of described square wave when demodulation probe 201 is positioned at n place, wellhole position for described shearing wave receiving processing circuit 40, n 〉=0, the n value is to represent that the air line distance between demodulation probe 201 and the vibration source 10 was 0 at 0 o'clock, and the big more expression demodulation probe 201 of n value is far away more apart from the air line distance of vibration source 10.Described computing unit 304 is used for computing counter at the count value N (n) of moment t0+tc during the t1 (n) constantly, and wherein, N (n) expression is positioned at the corresponding count value in n place, wellhole position with demodulation probe 201; Described computing unit 304 is controlled the described sine wave of described switching tube conducting at moment t0, and wherein, described tc is the time-delay of computing unit 304 preset trigger counting, and described computing unit 304 can be the most frequently used CPU.
As shown in Figure 3, described counting control unit 302 can comprise one be controlled by computing unit 302 often open flip-flop number switch k0 and a normally closed termination counter switch k1 who is controlled by described shearing wave receiving processing circuit 40, promptly send one during when computing unit 302 with the synchronous control signal of t0+tc constantly, often open flip-flop number switch k0 conducting, counter 303 begins counting, when shearing wave receiving processing circuit 40 is that send and t1 is synchronous control signal, normally closed termination counter switch k1 disconnects, and counting finishes.
At first, producing frequency by vibration source at moment t0 is the shearing wave of f1; Begin counting at moment t0+tc flip-flop number, the frequency of the trigger pulse of described counter is f2, and wherein, tc is the time-delay of preset trigger counting; The detection signal that comprises described shearing wave that will be positioned at the demodulation probe output at wellhole n layer place carries out anti-interference process, the output frequency that obtains importing the shearing wave receiving processing circuit is the square wave of f1, wherein, n is an integer, and the 0th layer is 0 for the vertical range between described demodulation probe and the vibration source; Described counter stops counting when the shearing wave receiving processing circuit receives the moment t1 (n) of described square wave.
The comprehensive shear wave velocity of stroke
The calculating formula process as follows, wherein, the unit of described time is ms, the unit of described frequency is MHz:
Td(n)＝t1(n)-t0-td (1)
Wherein, Td (n) passes to the duration of the demodulation probe 201 that is positioned at ground position n from vibration source for described shearing wave; Td is the time-delay that described reception processing unit 20 produces, and its numerical value is:
td＝t1(0)-t0-Td(0) (2)
Wherein, Td (0)=0; (3)
Wherein, D (n) is in the demodulation probe 201 at n place, ground position and the air line distance between the vibration source 10;
t1(n)-t0＝N(n)/(f2×10
3)+tc (5)
Aggregative formula (1) to (5) draws the comprehensive shear wave velocity of described stroke
For:
Shear wave velocity Vs between ground n2 position and the n1 position (computing method of n1 → n2) are as follows, and wherein numerical value n2 is greater than numerical value n1:
Vs(n1→n2)＝(D(n2-D(n1))/(Td(n2)-Td(n1)) (7)
Formula (1) and (5) substitution formula (7) are drawn:
Vs(n1→n2)＝(D(n2)-D(n1))×f2×10
3/(N(n2)-N(n1))
As from the foregoing, the method for measurement shear wave velocity of rock soil of the present invention is not only simple, and has the high and high characteristics of efficient of precision.
To sum up institute for preferred embodiment of the present invention, is not to be used for limiting practical range of the present invention only.Be that all equivalences of doing according to the content of the present patent application claim change and modification, all should belong to technology category of the present invention.
Claims (7)
1. a method of measuring shear wave velocity of rock soil is characterized in that: at first, be the shearing wave of f1 by vibration source in moment t0 generation frequency; Begin counting at moment t0+tc flip-flop number, the frequency of the trigger pulse of described counter is f2, and wherein, tc is the time-delay of preset trigger counting; The detection signal that comprises described shearing wave that will be positioned at the demodulation probe output at n place, wellhole position carries out anti-interference process, and the output frequency that obtains inputing to the shearing wave receiving processing circuit is the square wave of f1, wherein, and n 〉=0; Described counter stops counting when the shearing wave receiving processing circuit receives the moment t1 (n) of described square wave;
The comprehensive shear wave velocity of stroke at n place, described vibration source in-position
Computing formula as follows, wherein, the unit of described time is ms, the unit of described frequency is MHz:
Wherein, D (n) is in the described demodulation probe at position n place and the air line distance between the vibration source; N (n) is described counter in the count value of moment t0+tc during the t1 (n) constantly.
2. the method for measurement shear wave velocity of rock soil according to claim 1, it is characterized in that: the process that described vibration source produces shearing wave is as follows, frequency is that the dutycycle of f0 is that 50% original square wave carries out frequency division through frequency divider and obtains the basic square wave that frequency is f1, it is the sine wave of f1 that described basic square wave amplifies back formation frequency through shaping, and described sine wave makes super magnetic horn export described shearing wave at moment t0 under the effect of switching tube.
3. the method for measurement shear wave velocity of rock soil according to claim 1 and 2, it is characterized in that: described demodulation probe is under the effect of joining humorous electric capacity, make its resonance frequency also be f1, the process of the anti-interference process of described detection signal is as follows, and described detection signal forms the upward precipitous described square wave in lower edge after amplifying and amplify shaping through preposition amplification, frequency-selecting successively.
4. a system of measuring shear wave velocity of rock soil is characterized in that: comprise vibration source, receive processing unit, identification circuit and shearing wave receiving processing circuit;
Described vibration source comprises square-wave generator, and output frequency is that the dutycycle of f0 is 50% original square wave; Frequency divider carries out frequency division to described original square wave and handles, and obtaining frequency is the basic square wave of f1; Shaping and power amplification unit carry out the shaping processing and amplifying to described basic square wave, obtain the sine wave that frequency is f1; And, super magnetic horn, being connected with the described super magnetic horn of control between described super magnetic horn and described shaping and the power amplification unit is the switching tube of the shearing wave of f1 at moment t0 output frequency;
Described reception processing unit comprises demodulation probe, and described demodulation probe is joined and had that to make its resonance frequency be humorous electric capacity of joining of f1, and described demodulation probe is used to receive the detection signal that comprises described shearing wave; It is that the square wave of f1 is to described shearing wave receiving processing circuit that described reception processing unit is used for output frequency;
Described identification circuit comprises pulse producer, and output frequency is the trigger pulse of f2; Counter is used for counting under the effect of trigger pulse; Computing unit is used for computing counter at the count value N (n) of moment t0+tc during the t1 (n) constantly, and wherein, described shearing wave receiving processing circuit received the moment of described square wave, n 〉=0 when described moment t1 (n) was positioned at n place, position for described demodulation probe; Described computing unit is controlled the described sine wave of described switching tube conducting at moment t0, and wherein, described tc is the time-delay of computing unit preset trigger counting; Counting control unit, described counting control unit begin counting in moment t0+tc flip-flop number under the control of computing unit, stop rolling counters forward in moment t1 (n) under the control of described shearing wave receiving processing circuit.
5. the system of measurement shear wave velocity of rock soil according to claim 4 is characterized in that: described reception processing unit also comprises pre-amplification circuit, is used for described detection signal is carried out preposition processing and amplifying, obtains preamplification signal; Selective frequency amplifier circuit is used for described preamplification signal is carried out the frequency-selecting processing and amplifying, and obtaining frequency is the frequency-selecting amplifying signal of f1; Shaping amplification circuit is used for described frequency-selecting amplifying signal is carried out final shaping processing and amplifying, exports described shearing wave.
6. according to claim 4 or 5 described a kind of systems of measuring shear wave velocity of rock soil, it is characterized in that: described demodulation probe comprises a plurality of wave detectors that are positioned on the different directions.
7. according to claim 4 or 5 described a kind of systems of measuring shear wave velocity of rock soil, it is characterized in that: described shearing wave receiving processing circuit comprise one be controlled by described computing unit often open flip-flop number switch and a normally closed termination counter switch that is controlled by described shearing wave receiving processing circuit.
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| CN114035223B (en) * | 2021-10-22 | 2023-06-02 | 中冶集团武汉勘察研究院有限公司 | Dynamic compaction earthquake shear wave measuring device and method |
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| CN114035223B (en) * | 2021-10-22 | 2023-06-02 | 中冶集团武汉勘察研究院有限公司 | Dynamic compaction earthquake shear wave measuring device and method |
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