IDENTIFICATION OF GEOMECHANICAL AND GEOTECHNICAL STRUCTURES USING THE VIBROACOUSTIC METHOD FOR AUTOMATED STABILITY MONITORING SYSTEMS OF GROUND BUILDINGS AND MINE WORKINGS

Abstract

Purpose. Identification of geomechanical and geotechnical structures by vibroacoustic method to improve reliability and automation level of ground buildings and mine working stability monitoring. Methods. Classical wave theory, experimental studies in laboratory and field conditions. Results. The most important feature of acoustic wave propagation in fractured media is the complexity of the wave pattern, since at each boundary between adjacent layers four new waves are formed – two reflected (longitudinal and transverse) and two refracted, each of them, when falling on another boundary, will cause a similar process. In the near-surface layer, classical acoustic waveguides are formed – sections of rock limited in one or two directions by voids, cracks or other media. As a result, the divergence of waves to the sides is eliminated or reduced, so their propagation along the layers occurs with less attenuation than in an unbounded homogeneous or inhomogeneous medium. To control elements of geomechanical and geotechnical structures, normal waves (modes) propagated in such acoustic waveguides without changing their structure should be used. When upper limit of the frequency range for recording acoustic signal of the response of a plane-parallel or block structure to the applied shock is lowered, the range of possible sounding bases expands. Within this range, the first mode of normal resonant oscillations is registered, and its limits shift towards an increase of the absolute value. The identification of geomechanical and geotechnical structures for systems of automated vibroacoustic control of stability of the mine workings was carried out. Originality. It is established that system control is ensured by identifying local geomechanical objects as the systems with lumped parameters, and changes in the load of the system elements should be controlled by analyzing the compliance between parameters of the system’s response to the exciting stimulation and the quasi-stationary criterion. In contrast to the known methods, automated control should be carried out with taking into account the stages of the oscillatory process development. Practical implications. The research results contribute to improvement of reliability and automation of the ground buildings and mine working stability monitoring. Keywords: vibroacoustic methods, identification of geomechanical structures, ground buildings and mine workings stability, automation of mine workings stability monitoring.