The paper contains the statistical rows of rockbursts, sudden outbursts of methane at coal mines and ore mines in Russia for the period from 1954 to 2007, as well as the reflection in them of the eleven-year cycles of the Sun activity. Some results are presented of computer modeling of activation periods of outburst-hazardous state of rock mass at coal mines of the Kuzbass basin. Recommendations are given.
The paper presents the developed modeling program of geomechanical processes in fractured rock mass. In modeling one took into account the geometry of the mined-out space varying in the process of mining operations. Deformation and failure of rocks are modeled on directions with due account of varying anisotropy of deformational and strength properties. As a result, modeling enables to determine not only the fields of stresses and deformations, but also the failure zones and degree of strength attenuations and their orientation. An example of modeling of layer failure development of enclosing rock mass during mining of stratified deposit is included.
Consideration is given to the results of assessment of stability of the main transportation way of horizon of undercutting at the «Skalisty» ore mine of the Norilsk Co. – connecting slope. The mathematical modeling of the method for a working protection with a protective pillar has shown that this method will not ensure the stability of the mine working for the whole period of its exploitation. A new method was suggested for protection of the working with the use of preliminarily created stress relieving zone during formation of the packing massif.
The stress state of rock mass is determined by weight of overburden and the lateral earth pressure. It was stated that the stress state of rock mass has been originated with contribution of the lateral earth pressure in which the important role play the viscoelastic properties of rocks was obtained, which gives more precise assessments of stress state in rock mass than the determined ones with account of only elastic behavior.
A mathematical model of rocks as a continuous medium, describing the deformation and fracture along the oriented directions of existing or emerging systems of weakening, is proposed. Its main provisions: the strength of rocks of elementary volume is evaluated at each stage of loading along the possible directions; the degree of loading along the corresponding planes, determined by the acting stresses and strength properties along the planes of disturbances and solid material, is taken as a measure of stress state; irreversible deformation and destruction in the material develop along the planes with intensity that depends on the degree of loading along them. Examples of calculation of deformation of cylindrical samples of salt rocks under conditions of short-term and long-term laboratory tests using the proposed model are given.
