SU1315620A1 - Method of preventing rock shocks - Google Patents

Abstract

The invention relates to the mining industry and can be used in mining operations in a shock-hazardous massif. The goal is to reduce the cost of preventing rock bursts by reducing the volume of shock measures. To do this, using the instruments, acoustic emission (AE) intensity (number of pulses per unit time) is measured simultaneously by two amplitude levels. The first amplitude level is set to exceed the level of acoustic noise signals, and the second one to exceed the first, for example, twice. Then, the critical value of the intensity of the AE and the index b of the amplitude distribution of the pulses of the AE are determined. Mountain areas are identified in which at the same time the AE value exceeds the critical one and the amplitude distribution index of the AE pulses is less than or equal to one. Shockproof measures are carried out at these sites. The AE measurements are then repeated at two amplitude levels and the exponent b is determined. If b is again less than or equal to one, the vibration-hazardous measures are repeated. i (L O9

Description

The invention relates to the mining industry and may be used in mining operations in a shock-hazardous massif.

The aim of the invention is to reduce the cost of preventing rock bursts by reducing the amount of anti-shock measures.

The method is carried out as follows.

On the sections of the rock mass establish a converter of elastic waves into electrical signals. Instruments are used to measure acoustic emission intensity (the number of pulses per unit time) using two amplitude levels.

The first amplitude level is set to exceed the level of acoustic noise signals, and the second amplitude level is set to exceed the first, for example, twice. Amplitude levels can be any, but their values should be known. The critical magnitude of the acoustic emission intensity is determined for these impact rocks.

Then, the index of the amplitude distribution of acoustic emission pulses is determined by the formula

Ua,, and:

l, 1 - / :: -.

where b ,, aj

Uc ,,,

and.

the amplitude distribution of acoustic emission pulses; amplitude levels. AT;

acoustic emission intensity at amplitude levels a and a, imp / s, and allocate rock areas where the acoustic emission value simultaneously exceeds the critical one and the amplitude distribution index of acoustic emission pulses is less than or equal to unity (L1). And it is only in these areas that shock measures are carried out (for example, blasting camouflage explosive charges, drilling relief wells).

After performing the blowout preventive measure, the acoustic emission intensity is again measured at two amplitude levels and the indicator b is determined.

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If, then the measures are considered effective. Otherwise, additional anti-blowout measures are carried out.

Example. At the mine in the mine face at the horizon of 410 m, the intensity of acoustic emission is measured simultaneously over two amplitude levels for 20 min at 15 V

to and a, 0.3 V. At the same time, Uo, 50 imp in 15 s, and „30 imp in 15 s. The critical value of the acoustic emission intensity for impact-hazardous rocks of the mine is 3 pulses per 15 s.

 5 Indicator b is equal to:

, and,, db - and - / - 0.83. and “2 a

It has been established experimentally that in shock-hazardous rocks with an unstable steady state of destroying rocks, the proportion of acoustic emission pulses with large amplitudes (fraction of strong pulses) increases,

the expense of which decreases the index b.

25

Since CDd 503 imp in 15 s and b. anti-shock measures are carried out at this section of the rocks - blasting camouflage explosives charges,

30 located in the boreholes of the walls and slaughtering. Subsequent measurements of the acoustic emission intensity showed that U, 38 pulses in 15 seconds, pulses in 15 seconds at a, 0.15 V and a 0.3 V. Then, 1. This is a review35

telstvuet about the effectiveness of anti-shock measures.

Claims (1)

Invention Formula 40 A method of preventing rock bursts, including measuring the intensity of acoustic emission in a rock mass at an amplitude level, determining the critical magnitude of the intensity of acoustic emission of shock-hazardous rocks, conducting shock-proof measures in areas of rock with an intensity of acoustic emission that is higher than critical, and monitoring the effectiveness of these measures, due to the fact that, in order to reduce the cost of preventing rock bursts by reduce the volume of shock-proof measures, measure the intensity of acoustic emission simultaneously from two amplitude levels, determine the magnitude of the amplitude distribution 50 55 3 13156204 acoustic emission pulses according to the intensity of acoustic the ratio of emission at amplitude levels-V - / n x a and a-d, cps, and where b is the index of the amplitude ratio and shockproof measures of determining impulses in the rock mass tic emission, an indicator of amplitude distribution, and ai-amplitude levels, b .M, while measures are considered to be effective when reached.