Calculation of: Rock Quality Designation (RQD), Coefficients A2, A3, A4, A5, A6, A7, F1, F2, F3, F4, Basic RMR, Corrected RMR, Cohesion, Friction Angle, Deformation Modulus, Class, SMR (Slope Mass Rating).
In the design of civil engineering infrastructure, whether related to slope stability or underground works, it is often difficult to obtain detailed information on the strength and deformability characteristics of the involved rock mass. Therefore, it becomes essential to use a framework that can meet these requirements—an empirical method to solve problems arising from limited knowledge or experience in a specific area. The classifications by Bieniawski and Romana (the latter derived from the former, which was considered too ‘conservative’) address these needs and challenges. Bieniawski’s classification is based on field or laboratory surveys of six parameters:
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A1: Uniaxial compressive strength;
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A2: Rock Quality Designation Index (RQD);
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A3: Spacing of discontinuities;
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A4: Condition of discontinuities;
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A5: Groundwater conditions;
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A6: Orientation of discontinuities.
From these six parameters, the Rock Mass Rating (RMR, Bieniawski) is derived, and with the corrections introduced by Romana in 1985, the Slope Mass Rating (SMR).
In practice, RMR is differentiated as:
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Basic RMR (RMRb) = A1 + A2 + A3 + A4 + A5
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Corrected RMR (RMRc) = (A1 + A2 + A3 + A4 + A5) + A6