Experimental data on the relationship of the residual shear strength of rocks in closed cracks with the functional characteristics of intact rocks – the tensile and compressive components of adhesion, the roughness of the crack surfaces, and the level of normal stresses are presented. A unified integrated approach determines the shear strength of intact and destroyed rocks, the residual shear strength of closed rough cracks has been developed. The approach provides for the selection of stress intervals corresponding to different types of fracture, for each of which a strength criterion is proposed, expressed in terms of functional characteristics of intact rock. An express method for estimating the residual shear strength of rocks by cracks with a rough surface has been developed, in which an improved method of loading samples with spherical indentors is used as a basic test method. The express method implements the transition from the data of mechanical tests of samples with spherical indentors to the shear strength indicators for cracks in the rock mass, taking into account the level of normal stresses and the roughness of the crack surfaces measured in field conditions. In this case the roughness scale developed by Barton is used. The express method is informative and available in the fieldwork.
The paper presents results of an experimental study on strength characteristics of the rock mass as applied to the assessment of open-pit slope stability. Formulas have been obtained that describe a correlation between ultimate and residual strength of rock samples and residual shear strength along the weakening surface. A new method has been developed to calculate residual interface strength of the rock mass basing on data from the examination of small-scale monolith samples with opposing spherical indentors. A method has been proposed to estimate strength characteristics (structural weakening coefficients and internal friction angles) of the fractured near-slope rock mass. The method relies on test data from shattering small-scale monolith samples with spherical indentors, taking into ac- count contact conditions along the weakening surface, and can be applied in the field conditions. It is acceptable to use irregular-shaped samples in thetests.
Consideration is given to the method of the geometric addition of forces over the most stressed slip surface in estimation of open-pit slope stability. The limits of its application are defined.
The results of modeling and estimation based on the finite element method, of propagation boundaries of horizontal deformations with due account of structural features of rock mass, and also strength and deformational properties of various lithological differences composing the open-pit slope are represented.
With permanent increasing of depth of open pit exploitation stress strain behavior of side array changes, so the choice of the necessary and corresponding to reality geomechanical scheme is an important issue. Currently,there is large number of software to estimation the stability slopes. This article provides a comparison of different programs based on numerical method and the method of limiting equilibrium.
The analysis of graphs shows seismic events repeatability and seismic events distribution during the day, by days of the week and by months was made. It is shown, that seismic activity in Kuzbass region has a mixed natural and manmade character and figures of repeatability have interim character, the majority of seismic events occur in the time of blasting operations in open pit mining, but the distribution by month of the year corresponds to planetary pattern – the larg est number of events takes place in March, August and December. It was suggested that the spring increase in seismic activity lead to reduced stability of mine slopes during the snowmelt of landslides formation.
Estimation of earthquakes seismic effect for slope stability of coal strip mine «Chernigovets» in Kemerovo region by means of pseudo-static analysis and physical modeling is conducted. Relevancy to take into account not only maximum accelerations but also continuance of oscillations is showed.
The review of factors influencing rock mass strength is given. Methods of definition for sample strength changeover to rock mass are considered in the article.
