V. L. Shkuratnik

Correlation of thermally induced acoustic emission and ultimate compression strength in hard rocks

The authors have experimentally established and substantiated the relation between the ultimate compression strength and the low-temperature induced acoustic emission in the compressed hard rock specimens, averaged in a preset temparature range. This relation shows itself most clearly if data sampling is subjected to pre-censoring by withdrawal of data obtained on specimens with abormal defectiveness detected from the analysis of the thermally induced acoustic emission. The study case of the ultimate strength evaluation for Kapustinsky granite by using the thermoacoustic emission measurements is reported.

Acoustic emission in composites and applications for stress monitoring in rock masses

Experimental research is focused on the effect exerted by natural anisotropy orientation in some composites on the acoustic emission sensitivity of sensors. Acoustic emission is related with the angle of load application and lamination orientation in a composite. Based on cyclic test data, it is shown that the load application angle has significant influence on acoustic emission memory effect up to its complete vanishing. Considering the revealed mechanisms, the authors propose the method of stress-strain state control in mine design elements.

Using acoustic emission memory of composites in critical stress control in rock masses

The regular patterns of initiation and show of acoustic emission memory effect in a composite are experimentally obtained from tests on cloth laminate. The authors illustrate the capacity of cloth laminate as an absolute sensitive stress-to-acoustic emission converter. The designed and tested in-hole sensor enclosing this converter indicates when incremental stress surpasses a pre-assigned critical limit.

Kaiser Effect in Rock Salt

Using the results of experiments with rock salt samples under various loading regimes as an example, the regularities of the Kaiser effect formation and manifestation in rocks with plastic properties are investigated.

Kaiser Effect in Rocks Undergone Polyaxial Loading

The basic regularities are considered for manifesting the Kaiser effect in various regimes of polyaxial loading, which is of great importance for developing the methods of stress measurement in rocks. The correspondence between the results of experimental and theoretical investigations is shown.

Physical modeling of the grain size influence on acoustic emission in the heated geomaterials

Physical modeling of deformation of a hardening composite sample with a filler made of quartz sand with different grain sizes has established a relation between the acoustic emission parameters in the heated geomaterial, its grain size and strength. Anomalous acoustic emission has been revealed within definite heating temperature ranges, correlating the geomaterial strength in the first case and with the geomaterial grain size in the second case. The resultant experimental relation between the strength and grain size of agrees with the Hall-Petch relation.

Qualitative estimation of mineral grain sizes by ultrasonic laser spectroscopy

For elastic waves in geomaterials, the method is proposed to determine experimentally the frequency dependence of attenuation factor by ultrasonic laser excitation and estimate the characteristic sizes of mineral grains. An example is shown for using the method in question for structural analysis of ferrous quartzite samples.

Abnormality detection in a rock mass density profile based on the two-dimension seismic measurements

The article provides the theoretical justification and the estimation, using computer and physical modeling, for the detectability of abnormalities in density of rock masses based on the two-dimension seismic data and using direct and inverse 2D problems solutions for SH-waves.

Thermal nonlinearity effect used in laser excitation of ultrasonic signals in geomaterials

The possibility of creating laser-ultrasonic sources of short power pulses of elastic longitudinal waves on the basis of nonlinear thermal processes in the generator medium is examined theoretically and experimentally. A three-dimensional model of thermal nonlinearity is considered, and the waveforms, spectra, and directional diagrams of signals excited in geomaterials are calculated.