RU1822992C - Device for indicating acoustic emission of zones of dynamic structural rearrangement of geologic material - Google Patents

Abstract

Use: for non-destructive monitoring of the deformation state of mine workings, pillars of rocks JI-HZ1 J and engineering structures, as well as for research in the field of forecasting rock shocks and earthquakes. SUMMARY OF THE INVENTION: from an elastic energy converter 1 to an electric signal, it is transmitted to a preamplifier 2 and via a communication line 3 to blocks for determining the integrated amplitude 4, integrated energy 5 and the number of acoustic pulses 6. Unit 4 includes a linear detector or a balanced multiplier connected with a high-speed direction-to-frequency converter and a counter with a variable counting coefficient. This block can significantly increase the dynamic range of the detected pulses. Along with discrete pulses, the device can measure a noise signal of a constant and slowly varying amplitude. 3 ill. СО с 00 ю о о N3

Description

communication channel

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The invention relates to geophysical methods for studying the stress state of the earth's crust, in particular, to the prediction of earthquakes and serves to quickly identify zones of dynamic structural adjustment, determine their spatial location.

The purpose of the invention is to expand the dynamic range and increase the information content of measurements.

Figure 1 shows a block diagram of a device; figure 2 - block diagram of the integrated amplitude; Fig. 3 is a counter diagram with a variable counting coefficient.

The device contains N acoustic emission signal receivers, each of which consists of a series-connected elastic-to-electric energy converter 1, preamplifier 2. communication lines 3. integrated amplitude determination unit 4, integrated energy determination unit 5, acoustic signal quantity determining unit 6, digital-to-analog transducers 7, synchronization unit 8, and also block 9 for preliminary processing of information obtained in the unit for determining the number of acoustic signals.

This device operates as follows: an acoustic signal that arises in the object under study excites one or more converters 1 of elastic energy into electrical energy. The electric signal amplified by the preamplifier 2 is transmitted via a communication line 3 to the units for determining the integral amplitude and integrated energy 4.5 and the number of acoustic pulses 6.

The integral amplitude determination unit is arranged as follows. The signal from the communication line is fed to the input of the linear detector 10. The output unipolar signal is fed to the input of a high-speed voltage to frequency converter 11. Thus, during the integration time, which is set by the synchronization unit depending on the experiment task, the state of the counter 12 will be determined by the expression: S / IA (t) l dt. Definition Block

t

the integral energy of the signal is constructed in the same way as the integral amplitude determination unit, only instead of the linear detector 10 a multiplier is placed and the signal is supplied simultaneously to its two inputs, and the output of the balanced multiplier will have a signal proportional to the square of the instantaneous value of the signal amplitude, i.e. . during the integration time, the output of the counter 12 will be the state defined by the expression E / A (t) dt, i.e.

t

energy of the received signal over time g. Variable coefficient counter

account turns off the first counter 13 at the input of the switch and the second counter at the output from the last. The scheme works as follows: at the beginning of the counting cycle, until the 6th bit of the counter 15 is in the O state.

0 to its input comes the signal from the voltage converter to the frequency of the VLF through 1 - the input of the switch 14. After 32 pulses pass, the 6th bit of the counter 15 goes into state 1 and switches the switch 14. Now the input to the counter 15 comes only every second pulse from the VLF (the 2nd channel of the switch is working). Hence . The 7th bit of counter 15 will switch to state 1 after

0 passage of 96 pulses from the IF, After the 7th bit of the counter 15 goes to state 1, the signal from the IF takes place through the 3rd channel of the switch, i.e., the input from the IF 15 with a division ratio of 4, etc. Thus, the information capacity of the counter 15 will be 8160 pulses, i.e. the dynamic range of recording the signal energy is 78 dB with an 8-bit presentation of information.

0 The device provides the ability to measure the integrated amplitude (integrated energy) of either the entire signal, or only that part of it that exceeds the threshold of the comparator. The second mode is advisable under conditions of intense interference, not exceeding the level of the useful acoustic signal; the threshold is set above the interference level. In addition, this mode makes it possible to determine the average energy of one pulse during the integration time.

The invention has the following advantages: in contrast to known devices that do not use fully

5 data on the amplitude and duration of acoustic emission, having a higher sensitivity, this device makes it possible in principle to register not only the process of crack formation, as the most intense mechanism for generating acoustic emission, but also other mechanisms preceding crack formation and / or leading to internal rearrangement of materials and rocks, which makes it possible to select the entire set of acoustic emission signals by the nature of their generation and control of various stages of fracture tim material (elastic, plastic area, creep, creep, dilatancy treschinoobraeovanie

various levels). An important advantage of this device is its use under conditions in which discrete acoustic emission signals practically merge into continuous (duty cycle) and when discrete measurement methods give an uncontrolled error. This primarily relates to the growing process of deformation of the earth's crust during the preparation of earthquakes.

Claims (1)

SUMMARY OF THE INVENTION A device for recording acoustic emission of zones of dynamic structural adjustment of a geo-material, consisting of series-connected transforms Input from. -Sh Reset from sync device mechanical oscillator in the electric, amplifier, communication lines of the comparator, signal preprocessing unit, counter and recorder, distinguish In addition, in order to expand the dynamic range and increase the information content of measurements, a linear detector or a balanced multiplier, a high-speed voltage-to-frequency converter, and a counter with a variable counting coefficient, including the first counter at the input of the switch, are connected in series to the output of the communication line and a second counter at the output of the last connected to the input of the recorder. FIG. Z Output Fig.Z