Mining Institute, Ural Branch, Russian Academy of Sciences, Perm, Russia:

S. S. Andreiko, Head of Laboratory, Professor, Doctor of Engineering Sciences, ssa@mi-perm.ru
O. V. Ivanov, Senior Researcher, Candidate of Engineering Sciences

Belaruskali JSC, Soligorsk, Belarus:

I. A. Podlesny, Chief Engineer

Saint-Petersburg Mining University, Saint-Petersburg, Russia:
Yu. G. Sirenko, Associate Professor, Candidate of Engineering Sciences

The article presents the results of research aimed at development of a method for preventing gas-dynamic phenomena in roof rocks in entries to potassium stratum II at Belaruskali’s Mine Management 3. The geological and mining conditions of spontaneous roof collapse in the U-turn chamber of potassium stratum II were analyzed. The spontaneous collapse of roof rocks in the U-turn chamber according to the conditions of the roof rock failure behavior and consequences is classified as a delayed gas-dynamic phenomenon in the form of a sudden rock fall accompanied by gas release under the influence of free gas pressure in gas clusters induced in the contact areas in roof rocks undermined in the course of the U-turn chamber heading. The mechanism of delayed collapses of roof rocks accompanied by gas release in underground openings is analyzed as a case-study of entries to potassium stratum II using the in-mine experimental data on gas-dynamic characteristics of roof rocks non-undermined and undermined by stoping in potassium stratum III. Based on the estimates of the possible development of delayed gas-dynamic phenomena, the necessity of preventive degassing of roof rocks in the U-turn chambers and in other underground openings with a similar span is shown. The parameters of preventive degassing drilling in roof rocks of potassium stratum II in different geotechnical conditions are proposed with regard to the estimated patterns of contact clusters of free gases in roof rocks.

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