College of Mining, National University of Science and Technology–MISIS, Moscow, Russia:

A. S. Voznesensky, Professor, Doctor of Engineering Sciences, аl48@mail.ru
M. N. Krasilov, Post-Graduate Student
Ya. O. Kutkin, Assistant, Candidate of Engineering Sciences
V. V. Koryakin, Assistant

The College of Mining of the National University of Science and Technology—MISIS accomplishes R&D on Anker-Test device meant for the nondestructive inspection of rock bolts in underground mines. The device is equipped with the data recording and processing block with a display, which allows on-the-spot examination of rock bolting. The device implements the shock response spectrum analysis; measures amplitudes Am and frequencies Fm of maximums in percussion spectrums; and successively displays shape and spectrum of signals, and the identification diagram, where each signal is represented by a point in the Fm–Am frame. The field trial of Anker-Test device was carried out in underground excavations reinforced with polymer-coated steel rock bolts in KNAUF Gips Novomoskovsk mine. Two sites were selected for the tests: stope roof 11 m high, rock bolts 1.m long with the spacing of 0.5–1 m; crosscut roof 6.5 m high, rock bolts 1.2 m long with the spacing of 2 m. Prior to starting the tests, a few signals were recorded from the knowingly weak and high-tension rock bolts. These signals served as a reference. During laboratory processing of the recorded signals, the optimal signal bandwidth was selected. The frequency monitoring was based on values averaged over 10 signals. The article presents a diagram of standard parameters of signal spectra in the coordinates Fm–Am for high-tension and weak rock bolts in a stope roof. A t-test of difference of two population means shows that the hypothesis that two population means are equal is valid for samplings of the parameters of the consimilar states (both bolts are under high tension, or both bolts are weak). The samplings of the parameters of different states show that two population means are unequal. The trials display the efficiency of Anker-Test device in handling the set objectives.
This study has been carried out under research plan No. 109 in the framework of the basic part of the research assignment issued by the Ministry of Education and Science of the Russian Federation for 2016.

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