G. E. Yakovitskaya

Mechanical-electromagnetic transformations in rocks on failure

The authors present energy estimations of mechanical-electromagnetic transformations in rock specimens under compression that can be of use to diagnosing rockburst hazard rate in underground mines.

Background Electromagnetic Rock Radiation Recorded in Underground Workings of the Tashtagol Mine

Background electromagnetic radiation of rocks in underground workings of the Tashtagol mine at a depth up to 760 m is characterized by uniform distribution law with the parameters whose variation within monthly intervals does not exceed 5-20%.

Monitoring dynamic rock pressure events using improved EME recording instrumentation

The article reports electromagnetic emission (EME) measurements in rocks using REMI-2 equipment and recording–diagnosing system RDS REMI-3 developed jointly at the Institute of Mining and Novosibirsk State Technical University. REMI-2 measures EME signal strength and displays the results digitally. RDS REMI-3 is advantageous over earlier designed equipment as it downloads measurement data in the embedded memory. The EME records are displayed as oscillograms to enable detecting initial stage of rock failure based on analysis of change in structure, parameters and spectrum-and-time behavior of EME signals.

Integrated measurement and recording of loads, displacements and electromagnetic emission in rocks under uniaxial compression

The authors describe an automatized three-channel system intended for joint recoding of loads, displacements and electromagnetic emission in rock samples subjected to uniaxial compression testing. This system includes an optoelectronic displacement sensor. The developed and tested controller and computer product allow synchronous three-channel recording, analysis and processing of experimental data, and displaying of the analytical results.

A MODEL OF ELECTROMAGNETIC RADIATION SIGNALS OF LOADED ROCKS

UDC 622.831 Since the time of discovering electromagnetic radiation (EMR) accompanying the formation and growth of cracks [1] investigations of this phenomenon have developed in the direction of studying the physics of the process, in particular, a study of the kinetics of cracking of loaded rocks and in applied directions [2, 3]. On the basis of data on recording EMR pulses models of the kinetics of accumulation of cracks as a quasi-stationary stochastic process with independent increments [2] and correlated persistent (trend-preserving) pulsed process [3] were constructed. An experimental check of these models was based on calculating the number of pulses recorded during loading of the rock specimens under laboratory conditions, in which case the shape of the EMR signal, possibility of superposition of pulses in time, polarization of the signal, distance of the detector from the EMR sources (cracks), etc., were not taken into account. Consideration of the aforemen- tioned factors becomes especially urgent when investigating the process of cracking in large rock masses, where the rate of flow of EMR pulses can be considerable. In connection with this, it is necessary to develop a model of the EMR signal in interrelation to the kinetics of accumulation of cracks and shape of the EMR pulses from cracks taken individually. The purpose of the present work was to develop a model of the EMR signal occurring during cracking of rocks in interrelation to the kinetics of accumulation of cracks and shape of the EMR pulses from individually taken cracks.

Electromagnetic Signals during Static and Dynamic Loading of Rock Samples

The characteristic parameters are determined for electromagnetic emission signals during dynamic impact on the brittle and plastic rock samples. The dependence of variation in amplitudes, pulse duration, and spectral characteristics on the load is investigated.

Instrumentation System for Synchronous Recording of EME and Mechanical Deformation Parameters in Lab-Scale Tests of Rock Specimens

The instrumentation system designed for the synchronous recording of electromechanical emission and mechanical deformation parameters in lab-scale tests of rock specimens is presented. Based on the data of implemented tests, the change in the structure and spectrum of EME signals at the prediscontinuity stage in rocks is determined, and the failure prediction criteria are proposed.

Effect of external pulsed low-energy impact on destruction of pre-loaded rock specimens

The authors study the influence of external pulsed low-energy impact (blows) applied to different rock specimens exposed to loading up to failure on the electromagnetic radiation record layout.

Rock failure diagnostics based on structural changes in the electromagnetic emission signals by stages of rock loading

The paper discusses results of the laboratory loading of rock samples and synchronous recording of the electromagnetic emission and load rate. It is shown that appearance of low frequency components in the structure of the electromagnetic emission signals at the first stages of loading can be the sign of a discontinuity.

On Prediction of Rock Failure on the Basis of Recording the Pulses of Electromagnetic Radiation

The solution is considered for the problem on synthesis of optimal algorithm of failure prediction on the basis of recording the pulses of electromagnetic radiation. Poissons nonstationary process is taken as the model for radiant flow of pulses. Algorithms obtained ensure automatic trimming for the characteristics of background radiation. The characteristics of algorithm efficiency and results of practical approbation are given.