Modeling of Three Flat Coal Seams Strata Developing at Open Pit Miming Tatiana Gvozdkova, Sergey Markov, Nuray Demirel and Serony Anyona E3S Web Conf., 21 (2017) 01024 Published online: 10 November 2017 DOI: 10.1051/e3sconf/20172101024