SU1377389A1 - Method of evaluating strained state of rock body - Google Patents

Abstract

The invention relates to mining. The purpose of the invention is to increase the accuracy of assessment by improving the quality of selection of acoustic emission signals. Create an array of acoustic emission signals in the array. The reference spectra are determined during the technological break. The sensitivity of the receiver is selected so that the distance to the nearest noise source is 2–3 times its radius of sensitivity to acoustic emission signals. Allocate signals against the background noise and determine the intensity of the selected signals. The amplitude-frequency spectrum of each recorded signal is determined. Compare between themselves the magnitude of the correction signals with pre-defined standards of the amplitude-frequency spectra of various types of acoustic emission signals and process noise. Signals whose spectrum correction value is maximal with the reference spectrum of acoustic emission signals are triggered. For better informative-. The amplitude-frequency spectrum of the recorded spectrum is compared with at least two spectral standards corresponding to the stages of the deformation of the array. 2 hp f-ly, 1 ill. I (L

Description

The invention relates to mining and is intended to control the state of a rock mass.

The purpose of the invention is to improve the accuracy of assessment by improving the quality of selection of acoustic emission signals and increasing the information content.

The method is carried out as follows.

Initially, a source of acoustic emission signals is found or artificially created in the rock mass, during a technological break, signals are recorded, changing the distance between their source and receiver from a few centimeters to the radius of the maximum sensitivity of the latter by acoustic emission signals 5 m), and their spectra are determined, which are taken for reference. At the same time, monitor the deformations of the source of acoustic signals from the area of the array that are serving as the source and observe the recorded signals, respectively, the stages of elastic and elastic-plastic deformation of the section. The obtained spectra of the recorded signals are taken as reference for various stages of array deformation.

Then, also during the technological break, alternately commissioning the equipment serving as a source of interference and changing the distance between it and the receiver from a value of 2-3 of the above-mentioned radii to the value of the radius of the receiver’s sensitivity zone for a particular type of interference, and detecting noise spectra, which are reference spectra of technological noise.

Immediately before assessing the state of the array, the technological environment is analyzed taking into account the detected distances from the registration point to noise sources, the interference spectra standards are set, the receiver’s sensitivity is selected so that the distance to the nearest noise source is 2-3 times higher. The radius of the receiver's sensitivity zone was higher by the acoustic emission signals, and in accordance with it, the standards of the spectra of the acoustic emission signals are set.

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After that, a hole is drilled in the rock mass, a geophone is installed in it, its reliable acoustic contact with the massif is provided, and acoustic emission signals are recorded. Next, the amplitude-frequency spectrum of these signals is determined and its correlation values are determined with the standards of the amplitude-frequency spectra of various types of acoustic emission signals and process noise. The obtained correlation values are compared and the signals for which the correlation value of their spectrum with the reference spectrum of acoustic emission signals is maximum is selected. The intensity of the extracted signals is determined and the stress state of the array is judged by it.

The method can be implemented, for example, using a device whose block diagram is shown in the drawing.

The device includes a geophone consisting of a piezoceramic transducer 1 and preamplifier 2, amplifier 3, spectrum analyzer 4, analog-digital converter 5, random access memory 6, persistent storage 7, meter 8 of the correlation characteristics 8, microcontroller 9 and counters 10 pulses.

The processing of acoustic emission signals and noise by the specified device is as follows. When an acoustic pulse is applied to the geophone, the output of piezo transducer 1 generates an electrical signal with a frequency spectrum from 150 Hz to 150 kHz, an amplitude of 1-3 mV and a duration of 1-2 ms, which is amplified by preamplifier 2 and amplifier 3. Next, an analyzer 4 of the spectrum with the broadband spectrum determines the amplitude-frequency spectrum of the signal, which, after being converted by the analog-digital converter 5, is stored in the random access memory 6 for the time during which the correlation characteristics of the determination of the values of its correlation with the reference spectra recorded in the Permanent Memory 7 proceeds. Comparison between the correlation values of the signal classification according to its maximum value according to type

the source, the formation of the counting pulse in case the signal is received by the acoustic emission, and also the microcontroller Troller 9 controls the operation of the hardware complex in accordance with the program embedded in it.

The application of the proposed method makes it possible to increase the accuracy of estimating the stress state of the rock mass and to ensure an improvement in the quality of the prediction of the dynamic manifestations of rock pressure.

Claims (3)

1. A method for estimating the stress state of a rock mass, including registration in the signal array acoustic emission, their isolation from the background of noise and determination of the intensity of the selected signals, which are judged on the stress state of the array, characterized in that, in order to improve the accuracy of the estimate by improving the quality of the selection of acoustic emission signals, determine the amplitude-frequency five 0 five the spectrum of each recorded signal is compared with each other by the magnitude of its correlation with the predefined standards of the amplitude-frequency spectra of various types of acoustic emission signals and process noise and the signals are selected, the magnitude of which correlates the spectrum with the reference spectrum of acoustic emission signals is maximum. 2. Method POP1, characterized in that the reference spectra are determined during the technological break by selecting the sensitivity of the receiving device so that the distance to the nearest noise source is 2-3 times its radius of sensitivity to acoustic emission signals. 3. Method POP1, characterized in that, in order to improve the information content, the amplitude-frequency spectrum of the recorded signal is. They are compared with at least two spectra of the acoustic emission signal, corresponding to the stages of elastic and elastic-plastic deformation of the array.