SU1113544A1 - Method of determining stressed state of rock massif - Google Patents

Abstract

A METHOD FOR DETERMINING THE STRESSED STATE OF A MASSIF OF MOUNTAIN BREEDS, based on recording acoustic emission pulses that occur in the studied part of the massif during the drilling of a well, and determining their intensity, which is judged by the 6 state of the massif, characterized by , acoustic emission pulses are simultaneously recorded at two points of the array located from the bottom of the well at a distance (and at a distance from each other Cj.j 0.1 fo where (.g is the diameter of the bottom of the well, equalize them Pulse amplitude- by considering the attenuation coefficient breed and the distance between the points and matched in amplitude and fa.1e exclude pulses when determining intensiv§ NOSTA CO ate 4.:

Description

The invention relates to mining and is intended to determine the stress state of a rock mass using acoustic emission.

The known method for determining the stress state of an array of rocks is based on the registration of acoustic emission pulses and the determination of their intensity 1.

However, this method cannot be used in cases where natural acoustic emission is poorly developed or not observed at all.

There is also known a method for determining the stress state of a rock massif, based on the registration of acoustic emission pulses that occur in the studied area of the massif during the drilling process and determine their intensity, which determines the state of the massif {2J.

This method is characterized by low measurement accuracy, due to the fact that simultaneously with the acoustic emission pulses, pulses resulting from the interaction of a drilling tool with an array are recorded.

The aim of the invention is to improve the measurement accuracy.

The goal is achieved by the fact that according to the method of onsetting the stress state of a rock massif, based on the registration of acoustic emission pulses arising in the studied area of the massif during the drilling of a well, and determining their intensity, which determines the state of the array, the pulses acoustic emissions are simultaneously recorded in two fireboxes of the array located at the flank of the well at a distance f, and at a distance from each other (. ,, where fjj is the diameter of the flank of the well, equalize the amplitude pulses Therefore, taking into account the attenuation coefficient of the rock and the distance between the points and the pulses coinciding in amplitude and phase, are excluded in determining the intensity.

The essence of the invention is as follows.

In the studied area of the rock mass, the well is drilled and, receive signals at two points located at a distance from the bottom of the well (the point of application of external influence) fp, which is chosen so as to ensure that the size of the external impact area is small compared to Cd- In practice, the following condition is met, (l) j where C (is the maximum size of the area of external influence.

The receiving points have distance between each other, h-g, which is chosen

so that it provides a confident separation of received signals. In practice, comply with the condition

f,., lfo- (2)

Due to the fact that the zone of influence of the external influence is much larger than the length of the area of application of the external action and the coordinates of the emission points of the acoustic emission signals do not coincide with the coordinates of the point of application of the external action, it is possible to receive simultaneous registration as well as reception of signals at two points amplitudes of external stimuli signals, and non-simultaneous recording of informative acoustic emission signals.

The simultaneity of recording signals emitted at an external exposure point is achieved by forcibly delaying signals from the receiving point more closely located to the external impact point.

In this case, the delay time should be equal.

W, (3)

Ij delay time;

5 where

C, (. G, the distance from the point of application of the external influence to the points of reception;

C is the speed of propagation of elastic waves.

lilf

In the case of j. li, 1, 0.

Equality of amplitude of the signals emitted at the point of external influence is achieved by adjusting the amplitude of the signals from one of the receiving points, taking into account the coefficient of rock attenuation and the distance between points.

The drawing shows the device by which the proposed method is carried out.

The device comprises a receiver 1 connected to the meter 2, an additional receiver 3 located at a distance less than or equal to the distance from the first receiver to the point of application of the external influence and connected to the meter 2 through the amplitude controller 4, the delay line 5 and the inverter 6.

The device works as follows.

The signals from the receiver 1 are fed to the input of the meter 2.

The signals from the Additional receiver 3 are fed to the input of the amplitude control 4, which is adjusted to the minimum meter reading. This achieves equality in amplitude of the signals emitted at the point of external influence and received by receivers 1 and 3. From the output of the amplitude controller 4, signals arrive at the input of delay line 5, the delay time of which is determined by formula (3). The delay line provides simultaneous input to the meter input 2 signals emitted at the point of external influence and received by receivers 1 and 3. From the output of the delay line 5, the signals received by receiver L are fed through inverter 6 to the input of meter 2 and summed up with signals received by the receiver 1. Since the signals emitted at the point of external influence and received by receivers I and 3 are equal in amplitude and arrive at the input of meter 2 at the same time, but opposite in phase, they mutually exclude each other. At the same time, acoustic emission signals emitted outside the point of external action, entering the input of the meter 2, are recorded by it.

Registered acoustic emission pulses determine the normalized acoustic emission intensity N N

NHE-normalized acoustic emission intensity;

NO- the intensity of acoustic emission at the working wall;

N is the intensity of acoustic emission at a distance

X from the production wall.

By changing the value of N, one can judge the stress state of the rock mass and the position of the maximum of the reference pressure zone.

The advantages of this method are that, by improving the reliability and reliability of estimating the stress state of sections of a rock mass, it is possible to more reliably and reliably determine the likelihood of dynamic occurrences of rock pressure (rock blows, sudden emissions of coal, rock and gas) , to evaluate the results of measures aimed at reducing the pressure of the mountains, more correctly determine. modes of support and mining mechanisms, which is important to ensure the safe conduct of mining operations 5 and to prevent injuries to mining workers.

Claims (1)

METHOD FOR DETERMINING STRESS STATE OF ARRAY ROCKS, based on the registration of acoustic emission pulses arising in the studied area of the array during the drilling of the well, and the determination of their intensity, according to which the state of the array is judged, characterized in that, in order to improve the accuracy of measurements, acoustic emission pulses are simultaneously recorded in two points of the array located from the bottom of the well at a distance and at a distance from each other 2> 0.1 t _o , where lg is the diameter of the bottom of the well, the impulses are equalized in amplitude, taking into account the rock attenuation coefficient s and distances between points and pulses coinciding in amplitude and phase are excluded when determining the intensity. SU,. „1113544