Author 1:
Name & Surname: Nikolenko P. V.
Company: College of Mining, National University of Science and Technology—MISiS (Moscow, Russia)
Work Position: Assistant Professor
Scientific Degree: Candidate of Engineering Sciences
Contacts: ftkp@mail.ru

Author 2:
Name & Surname: Nabatov V. V.
Company: College of Mining, National University of Science and Technology—MISiS (Moscow, Russia)
Work Position: Assistant Professor
Scientific Degree: Candidate of Engineering Science

The article presents a promising method to control stresses and strains in rock mass based on acoustic emission and stress memory effect in some anisotropic composites. In the continuous monitoring mode, the method allows detecting the excess of a preset critical level by major principal stress and estimating the stress orientation change in the plane orthogonal to the measurement hole axis. Based on the analysis, the most appreciable interference capable to reduce accuracy and reliability of stress control is moisture pin the control zone and natural and induced acoustic noise. It is experimentally proved that even a short-term contact with water results in considerable distortion of stress memory effect and, consequently, in loss of efficiency of control using a composite such as cloth laminate PTK. It is found that hydrophobic coating totally eliminates influence of moisture on acoustic emission and stress memory effect in a material under testing. In the framework of a lab experiment, it is shown that acoustic noise is an interference that exerts substantial impact on detection of acoustic emission in the tested specimens. At a signal/noise ratio close to one, the stress control efficiency is minimal. The authors propose an efficient filtering procedure based on using crosscorrelations between the reference and test signals and based on data censoring on the ground of their statistical analysis. The procedure enables identification of acoustic emission signals against noise background at the equal ratio of amplitudes of the signals and noise, and makes it possible to determine exact time of acoustic emission-based stress memory effect in the tested specimen of an anisotropic composite. With such filtering algorithm, the interference protection and reliability of stress monitoring in rock mass around excavations are highly improved.
The study was supported by the Russian Foundation for Basic Research (Agreement No. 14-05-31201\15).

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