Nowadays, studying creep behaviors of rocks is of a great significant in constructing underground structures. The current methods for determining creep parameters of rock masses are mostly procured in laboratories using processed rock specimens. The disadvantage of the abovementioned methods is the neglect of cracks and the homogeneity of rock masses. Therefore, to estimate accurately true creep behaviors of rocks, it is necessary to translate creep parameters of rock specimens in laboratory into those of in-situ rock masses. The authors present the method for determining creep parameters of rock masses using bending-compression tests and transforming Even-Hoek’s deformation modulus formula. As a result, the translated formula of creep parameters between rock specimens and rock masses is acquired.


During exploitation and operation of underground constructions numerous defects and deflection of bearing structures are observed due to the lack of consideration for rheological processes in rock masses. Rock rheological mechanism comprises two basic processes, which are defined as relaxation and creep. Both of them relate to the continuous adjustment of strain and stress states in rocks with time. Creep tests are carried out by applying a constant static load on the test specimens. Afterwards the curve dependencies of gradually increasing deformation or displacement on time are recorded. The graphics of rock specimens relaxation behaviors are plotted by fixing the values of applied prescribed deformation on test specimens and recording the reduction of tress with time. Besides, the term of “long-term strength” also is used to describe rheological behaviors of rock masses based on the results gained from creep and relaxation tests at various loading states [1, 3, 5].

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