ИСТИНА

The report presents the experimental study of the damage evolution under triax-ial non-proportional loading of sandstones using the Triaxial Independent Loading Test System (TILTS) with in situ continuous registration of acoustic emission (AE) signals on the TILTS’ load-ing plate and stress-free faces of the cubic samples. A comparative analysis of the AE data reg-istered on the samples and the plate was carried out which allowed establishing the qualitative correspondence of the change of AE total counts during the sandstone deformation. The conducted experiments prove that it is possible to register AE by fixing the sensor on one of the TILTS’ loading plates, thus to measure AE under non-proportional unequal-component compression. In addition, the location of the AE sensor on the TILTS’ plate allows registering AE signals at the stages of localization, fragmentation and macrodefect growth when there is a significant discontinuity of the damaged sample. This makes it possible to obtain information on the nature of damage evolution even at the strain-softening stage and gives new prospects for studying the damage accumulation under triaxial proportional and non-proportional loading of rocks. For proper studies of the energy redistribution principles during damage occurrence and evolution, a two-level structural-phenom-enological model of quasi-static deformation of brittle rocks was developed. The model allowed to introduce quantitative measures that can be used to describe the conditions for the transition to localized failure and decoding of AE signals.