Author 1:
Name & Surname: Andreiko S. A.
Company: Mining Institute, Ural Branch, Russian Academy of Sciences (Perm, Russia)
Work Position: Head of Geotechnological Processes Laboratory
Scientific Degree: Doctor of Engineering Sciences
Contacts: e-mail: ssa@mi-perm.ru

Author 2:
Name & Surname: Litvinovskaya N. A.
Company: Mining Institute, Ural Branch, Russian Academy of Sciences (Perm, Russia)
Work Position: Researcher
Scientific Degree: Candidate of Engineering Sciences

Author 3:
Name & Surname: Lyalina T. A.
Company: Mining Institute, Ural Branch, Russian Academy of Sciences (Perm, Russia)
Work Position: Engineer

Associated with activation of hazardous gas dynamic processes (GDP) in shearer mining of potassium salt such as sudden failure of floor rock mass together with gas emission in underground excavations in Berezniki Mine-4 and Berezniki Mine-2, the geological and structural conditions of GDP sources in salt rock mass have been studied and described in the article. Geological and mine-technical conditions of floor rock failure in underground excavations are analyzed. Free gas content of floor rocks is tested inside the areas of anticlinal fold dislocations and linear potassium bedding. Statistical analysis of data on gas content of different areas in the salt rock mass is performed. It has experimentally been proved that different areas of the salt rock mass have different gas content, and this is not due to stochastic variation of gas content in experimental samplings. Based on the experimental findings, the mechanism of formation of gas dynamic event sources in the areas of anticlinal fold dislocations has been determined. The sources of gas dynamic events in the excavation floor rocks occur at strike joints (exfoliation and separation) and transverse fractures at roots of the anticlinal folds. An approach is formulated and recommendations are made on predicting hazardous sites where floor rock failure is probable in development and breakage headings in potassium mines. Based on the research findings on gas content and gas dynamic characteristics of salt rock mass, parameters ((length and spacing) of preventive degassing hole drilling in the floor of underground excavations are substantiated as the basic means of avoiding sudden floor rock failure accompanied with gas emission. The offered method has been trialed and recommended for all potassium mines of Uralkali.
This work was supported by the Russian Foundation for Basic Research and by the Perm Krai Government, projects nos. 07-05-97607, 09-05-99023, 11-05-96023.

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