During the last thirty years, the increasing need for extracting coal from new mining fields, especially from unmined protective pillars and seams that are threatened with rock bursts and rock-gas eruptions, has accelerated the development of research in the fundamental mining discipline known as rock mass mechanics or geomechanics. Generally, rock mass mechanics is concerned with rock mass movements and with the phenomena accompanying them. Extensive theoretical, laboratory, and in-situ investigations have resulted in considerable achievements in the field of rock mass mechanics. It is impossible to include all these achievements in a single monograph, and therefore in the present book the author has attempted to contruct a synthetic mathematical description of the rock mass movements and of the strain and stress state induced by mining, in particular when extracting mineral deposits.