ABSTRACT
The reliability of slopes stability analysis of open pits depends not only on the correctness of the chosen design scheme and method, but also on the physical and mechanical properties of the rock mass taken into account. In this regard, it is suggested to measure the strength characteristics of the rock mass with account of the slope stress state and its failure mechanism.
In the capacity of failure mechanisms of constructive elements of the open pit slopes the following types were considered: slope destruction by cutting and reversing of strong blocks with no unfavorably oriented weakening surfaces; the implementation of a special limit state along an extended weakening surface; mixed failure mechanism, which includes the actualization of a special limiting state along the weakening surface, and joints development by cutting and reversing blocks of rock as well.
Using failure envelope Mohr circles stresses as rock mass strength estimate indicators, corresponding to conditions of uneven volume compression and joint action of both compressive and tensile stress is suggested.
A phenomenological approach to assessment of the strength criteria of a rock mass is suggested basing on the results of a complex mass laboratory tests of samples including volume compression (suppressing stabilometric tests), splitting with counter-directed spherical indenters and cutting under compression along the weakening surfaces (joints of both natural and man-made origin), taking into account the lithological composition and jointing parameters (orientation and intensity of joint systems) of the mass.
Formulae to measure the calculated parameters of the strength certificate (adhesion and angles of internal friction) of the rock mass through analogous indicators of solid specimens, taking into account the jointing parameters, the type and intensity of the stressed state in the rock mass are suggested.
