RU2071563C1 - Device for determining degree of rock mass impact- or outburst-hazard - Google Patents

Abstract

FIELD: mining engineering. SUBSTANCE: determination of degree of hazard and registration of pulse emittance of electromagnetic or resilient oscillations of crushing fissures caused by ultimate stresses are effected by device having in series connected sensor of acoustic or electromagnetic emission, primary amplifier, attenuator, peak-amplitude amplifier and recorder, also pulse shaper and indication unit. Device is provided with energy indicator, switchgear, analogue-digital converter, and microprocessor unit. Amplifier output is connected with first inputs of peak-amplitude recorder, energy indicator, event shaper with its output connected with second input of analogue- digital converter whose first input is connected with switchgear output. First and second inputs of switchgear are connected with outputs of peak amplitude recorder and energy indicator respectively. Output of analogue- digital converter is connected to indication unit input through microprocessor unit which is double-way communicated with attenuator, amplifier, peak- amplitude recorder, energy indicator, event shaper, and switchgear. EFFECT: high efficiency. 6 dwg

Description

 The invention relates to mining and can be used to assess the degree of danger of sections of mine workings by dynamic phenomena such as rock shocks or sudden emissions of coal, rock and gas by registering pulsed radiation of electromagnetic or elastic vibrations from fracture cracks formed in the rocks around the stresses underground workings.

 A device for determining the degree of impact hazard of sections of a rock massif (ed. St. CCCP N 1421862, E 2 C 39/00, 1988), comprising a series-connected sensor, pre-amplifier, high-pass filter, attenuator and amplifier, giving parallel channel in each of which includes a threshold element, pulse shaper and counter, connected in series, as well as a trigger, an OR element, and an indication unit. This device counts the number of N (A1) and N (A2) pulses exceeding the amplitude of two fixed thresholds A1 and A2, and the observation time is limited to reaching the specified capacitance of the counter N1 or N2 on any channel. The difference N (A2) and N1 (filling the counter N1) or the difference N (A1) and N2 (filling the counter N2) is determined and the danger is estimated by the sign of this difference: if the sign is positive, then the coefficient b for the power-law dependence of the activity of seismic acoustic pulses on the amplitude is positive and the site is not dangerous, if the sign is negative, then the coefficient b is negative and the site is dangerous.

In the specified device:
fixed amplitude thresholds sharply limit the range of favorable operating conditions of the device,
the absence of restrictions on the maximum signal amplitudes does not allow selection of high-amplitude industrial noise,
the time for collecting information is not fixed, which does not allow to compare the activity of emissions in different areas,
hazard assessment only by the sign of coefficient b is not sufficiently reliable.

 Closest to the invention in technical essence is a device for determining the degree of shock hazard of rocks by acoustic emission according to ed. St. USSR N 1520243 E 21 C 39/00, 1989, which contains a series-connected sensor, preamplifier, filter, amplifier, amplitude selector, as well as a shaper, counters, dividers, a pulse number input unit, comparison units, a timer, AND and OR elements, indicators. In this device, the activity of acoustic emission N (a1) and N (a2) is determined on two thresholds a1 and a2 of amplitude selection, according to the values of N (a1) and N (a2) for a given ratio a1 / a2, the pulse amplitude distribution index b is estimated, then by the activity of acoustic emission at the first threshold N (a1) and indicator b, the shock hazard category is determined as follows: if N (a1) is higher than the critical value n1, then the degree of shock hazard of the site is determined by comparing the indicator b with its critical values B1 and B2, and if B1 < b <B2, then the site is referred to dangerous (category 2), and if b <B1, then the site is classified as especially dangerous (category 1). For b> B2, the site is considered non-hazardous (category 2) (see figure 5).

However, in this device:
the upper threshold of the amplitude of informative signals is not set, which does not allow to exclude the influence of high-amplitude industrial interference;
the readings are compared only at two amplitude levels a1 and a2 (at two points of the distribution index b), which leads to a high error in calculating the parameter b;
the selected amplitude ratio a2 / a1 is a constant for this device, and when the level of signal amplitudes changes, the error in measuring signals of different dynamic ranges will be different;
assessment of the shock hazard category does not include selection of passage during the collection of information about the state of an array of random interference signals, leading to distortion of the results;
the use of one parameter n1 as a criterion worsens the reliability and reliability of the forecast, because there are cases when the degree of shock hazard varies from the 3rd category to the 1st without an intermediate stage (see Fig. 5), which leads to unreasonably high costs for the application of control measures in non-hazardous areas.

 To increase the reliability of the forecast and determine the degree of impact and outburst hazard of rocks, a device is proposed that contains a serially connected acoustic or electromagnetic emission sensor, a preamplifier, attenuator, an amplifier and a peak amplitude meter, as well as a pulse shaper and an indication unit equipped with an energy meter, commutator, and analog -digital converter and microprocessor unit. The output of the amplifier is connected to the inputs of the peak amplitude meter, energy meter, and event shaper, the output of which is connected to the second input of the peak amplitude meter and to the first input of the analog-to-digital converter, the second input of which is connected to the output of the switch. The outputs of the peak amplitude meter and energy meter are connected respectively to the first and second inputs of the switch, the output of the analog-to-digital converter is connected to the input of the display unit through the ports of the microprocessor unit, and the microprocessor unit is connected by two-way communication with an attenuator, amplifier, peak amplitude meter, energy meter, shaper events and switch.

 Figure 1 shows the structural diagram of the device; figure 2 output signals of the sensor, attenuator and amplifier; figure 3 distribution of accounts by amplitude levels; figure 4 the principle of determining the shock and outburst hazard with two thresholds n1 and n2; figure 5 the principle of determining the impact hazard at a single threshold n1 (as in the prototype), figure 6 distribution of bills by energy levels. Figures 4 and 5 indicate: A amplitude, N number of events, n1 and n2 criteria values for the number of events obtained at the data set stage, B1, B2 criteria values of the amplitude distribution of pulses obtained at the data set stage, 1, 2, 3 degree danger. The dots show the results of measurements, the lines show the interface between different degrees of shock hazard.

 The device contains (Fig. 1) a series-connected sensor 1, preamplifier 2, attenuator 3, amplifier 4. The output of amplifier 4 is connected to the inputs of a peak amplitude meter 5 and an energy meter 6, the outputs of which are connected to the inputs of the switch 7. The output of the switch 7 is fed to the input analog-to-digital converter (ADC) 8. The output of amplifier 4 is simultaneously connected to the input of an event shaper 9, which controls the operation of peak amplitude meter 5 and the operation of ADC 8. The signal in ADC 8 is digitally displayed on the display of the display unit 10 devices through the ports of the microprocessor of the microprocessor unit 11. Each of the above nodes, except for the sensor, the ADC preamplifier, and the indicating unit, is connected by complex multi-wire connections to the microprocessor unit 11, constructed, for example, based on the K 1830 BE31 microprocessor set. This kit contains a standard set of functional units: the microprocessor itself, random access memory (RAM), programmable program memory, keyboard (not shown in the drawing). The microprocessor unit 11 receives and sends information to the device units via standard microprocessor ports, generates a timing diagram for controlling the operation of the device, supports keyboard and display unit maintenance and an interactive dialogue with the operator at the stage of entering the initial parameters and outputting the results to the computer in order to obtain a hard copy (printout ) results and (or) further processing by high-level programs at the stage of developing criteria. Also, the microprocessor unit 11 receives information from the ADC 8.

 The device analyzes two parameters of the emission process: activity and an indicator of the amplitude distribution of signals.

The device operates as follows. Using the keyboard or entering a list of parameters from the program memory in the microprocessor unit 11, the initial registration parameters are set as time-valid measurement data. These parameters include:
minimum amplitude threshold for recording Amin signals;
the maximum amplitude of the extracted Amax signals, while signals with an amplitude above Amax are not accepted as uninformative;
the duration T of a single cycle of information accumulation with intermediate processing of its results,
minimum energy threshold for recording signals Emin;
the maximum energy of the emitted signals Emax, while signals with an amplitude above Emax are not accepted as uninformative;
integration time τ;
the number C of unit cycles in one dimension;
criteria for assessing danger according to the indications of a single cycle in the form of ultimate emission activity n2 and n1 and limit indicators of the amplitude distribution of B2 and B1 corresponding to 1.2 and 3 hazard categories;
Hazard assessment criteria for a series of unit cycles, in the form of limiting values k2 and k1 of the arithmetic average of the category from the unit ratings obtained in the series, k2 (for the 2nd category) and k1 (for the 1st hazard category).

 When assessing the hazard category by measuring the energy of emission pulses, the same criteria n1, n2, B1, B2, k1, k2 are used as when measuring peak amplitudes, but their values are different in absolute value.

 All of the above parameters are set according to the results of preliminary experimental work at the mines of this basin and then remain constant at different measurement points.

 The emission sensor 1 is installed on a controlled area of the output, give it the desired orientation and position, and turn on the peak amplitude measurement mode using the keyboard of the microprocessor unit 11. In this case, the sensor 1 converts the signals from sources located in the zone of the reference pressure of the output into electrical oscillations at the operating frequency (Fig. 2A), which, after preliminary amplification in the preamplifier 2, are fed to the input of the attenuator 3 (Fig. 2b), and then of the amplifier 4 (Fig. 2c), where the signal amplitude is converted, After that event generator 9 via the microprocessor unit 11 performs selection signal amplitude, duration and repetition frequency. Event generator 9 is a comparator with several counters connected to it, an adder and a single-shot (not shown in the drawing).

 Pulse signals selected by means of the shaper unit 9 as informative ones are identified as individual events with a characteristic in the form of peak amplitude A and from the output of the meter 5 through the switch 7 are fed to the ADC 8, and then digitally to the microprocessor unit 11. The entire range of the amplitudes of the recorded signals from Amin to Amax subdivided into a given number n> 2 bands with an increasing lower level of Ai, where i varies from 1 to n. The lower level of the first band is Amin, and the upper level of the nth band is Amax (Fig. 3). In the microprocessor unit 11, the amplitude A is compared with the threshold Ai of each of the n amplitude bands. The comparison results are realized in the form of adding a unit of account to one of n counters of the number of Ni events exceeding the level of AI. Event counters are organized programmatically in the RAM of microprocessor unit 11. Figure 3 shows the linearized distribution of peak amplitudes A of the generated event pulses at n amplitude levels. Аi peak amplitude of the i-th pulse of the event, falling into the i-th amplitude level and counted by the i-th counter as an Ni event.

 At the end of the specified observation time interval T, the amplitude distribution b and the average value Nc of the emission activity at the Amin threshold are calculated in the microprocessor unit 11 for n pairs of the threshold AI and the corresponding number of recorded events Ni.

 If, when registering radiation, the Ni event count is recorded in more than 3 amplitude bands, then the impact or outburst hazard is evaluated in the peak amplitude measurement mode, as described above. If events are recorded in three or less bands, i.e. with a low differentiation of signals by amplitudes, using the keyboard of the microprocessor unit 11, the device is put into energy measurement mode. The signal from the output of amplifier 4 goes to the input of the peak amplitude meter 5, energy meter 6, the outputs of which are connected to the input of the switch 7. The output of the switch 7 is fed to the input of the ADC 8. However, when operating in the energy measurement mode, the switch 7 passes the signal to the input of the ADC 8 only from an energy meter, which is an integrator with a given integration time t and with a control key from a microprocessor unit 11. For a given time T, the number of events T / τ is generated that are distributed according to the energy level Ei in accordance with FIG. 6 is similar to the distribution of peak amplitudes (FIG. 3). Then, the informative signals selected by the meter 6 from the output of the ADC 8 enter the microprocessor unit 11, where the signal energy E is compared with the threshold Ei of each of n energy levels. The comparison results are processed in the same way as in the peak amplitude measurement mode.

 At the end of the time interval T, the energy distribution index b and the averaged value Nc of emission activity at the threshold Ec are calculated for n pairs of threshold values Ei and the corresponding number of recorded events Ni (Fig. 6).

 The choice of a measurement mode for assessing the degree of impact and outburst hazard of rocks (by peak amplitude A or by energy of signals E) is made depending on the degree of differentiation of the input signal: if it is insufficient to isolate a particular event and assign it to any amplitude level, then go to the registration of artificially generated events with their subsequent assignment to a particular energy level, which allows us to identify stress state anomalies by slowly varying signals alam.

Next, the values of Nc and b are compared with the hazard criteria (figure 4) and determine the hazard category of the site from the condition:
if Nc <n2 for any b or Nc> n2, b> B2, then the rating is “non-hazardous” (category 3);
if n2 <Nc <n1, b <B2 or Nc <n2, B1 <b <B2, then the rating is “dangerous” (category 2);
if Nc> n1, b <B1, then the rating is “increased danger” (category 1).

 When conducting a series of observations in one measurement (C> 1), the numerical values of the shock and outburst hazard categories obtained in unit cycles are summed up and, at the end of the measurement, the device calculates the arithmetic mean value (k) of the estimate and compares it with the criteria: if k <k2 , then the rating is “not dangerous” (3rd category), if k2 <k <k1, then the rating is dangerous (2nd category), if k> k1, then the rating is “increased danger” (1st category).

 Using the device, unlike the prototype and other devices of a similar purpose, significantly increases the reliability and reliability of the forecast and assessment of impact and outburst hazard of rocks and allows you to select the optimal values of the measurement parameters (Amin, Amax, T, C, n1, n2, B1, B2, k1 , k2) in a wide range and, if necessary, change them directly in the mine with regard to different mining and geological and mining conditions, as well as automatically measure at the selected optimal param values moat, providing for the selection of the interference, the accumulation of information, analysis and delivery of the final result in a hazard assessment categories directly in the mine without any operator in the calculations. In addition, the use of the invention improves the accuracy of determining the index of the amplitude distribution b and the averaged activity Nc by increasing the number of comparable levels of assessment of emission activity to n> 2; moreover, to evaluate these parameters, different options for approximating the distribution can be set, depending on the processing program ( linear, exponential, exponential, etc.), allows to increase the reliability and reliability of the separation of hazardous areas from non-hazardous and highly dangerous due to the introduction of double gradation of the criterion of limit activity (along with n1, its lower level n2 is introduced), which allows us to differentiate the volume and cost of the costs of measures to bring the site into a non-hazardous state.

 The invention also makes it possible to automatically perform a series of measurements and evaluate the hazard category by the ratio of the category ratings for individual reports in the series, which significantly increases the reliability of the received information by eliminating random noise.

Claims (1)

 A device for determining the degree of shock and outburst hazard of rocks, containing a series-connected acoustic or electromagnetic emission sensor, a preamplifier, attenuator, amplifier and peak amplitude meter, as well as an event shaper and an indication unit, characterized in that it is equipped with an energy meter, a switch, analog a digital converter and a microprocessor unit, the amplifier output being connected to the first inputs of a peak amplitude meter, an energy meter, and an event shaper, the output of which is connected to the second input of the peak amplitude meter and to the second input of the analog-to-digital converter, the first input of which is connected to the output of the switch, the first and second inputs of the latter are connected to the outputs of the peak amplitude meter and energy meter, respectively, the output of the analog-to-digital converter is connected to the input the indication unit through a microprocessor unit, and the latter is connected by two-way communication with an attenuator, amplifier, peak amplitude meter, energy meter, former event and switch.

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