Research Center for Geomechanics and Mining Practice Problems, Saint-Petersburg Mining University, Saint-Petersburg, Russia:

S. V. Tsirel, Senior Researcher, Doctor of Engineering Sciences
A. A. Pavlovich, Head of Laboratory, Candidate of Engineering Sciences, pavlovich_aa@pers.spmi.ru
N. Ya. Melnikov, Researcher, Candidate of Engineering Sciences

The optimal and stable ultimate pitwall limit design is highly critical for safe open pit mining. Currently, open pit mining is carried out increasingly more often in difficult geological conditions, including steeply dipping bedding. Given such conditions, the pitwall slope stability is a challenging problem, and the conventional designs of pitwall parameters lack reliability. Anti-dip bedding slopes deform with origination of large fractures while preserving the overall stability, with the safety factor higher than the standard value in isotropic slope designs. Stability estimation of such slopes should take into account both the load-carrying capacity of a slope and the eventual displacement size. On this basis, and from the joint physical and numerical modeling evidence, a procedure has been developed to determine pitwall parameters starting from the initiation of large fractures, by means of allowable displacement calculation and graphical determination of the stability factor of a slope at any stage of deformation. The procedure proves that the integration of the physical simulation and numerical modeling allows benefitting from both. The physical simulation reveals peculiarities of pitwall deformation. The numerical modeling supports designing in various geological and geotechnical conditions. Collation of the results enables more reliable prediction of slope stability in different conditions much in advance of a limit state.

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