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The most widely used definition was developed in 1964 by D. U. Deere. It is the borehole core recovery percentage incorporating only pieces of solid core that are longer than 100 mm in length measured along the centerline of the core. In this respect pieces of core that are not hard and sound should not be counted though they are 100 mm in length.
The following 13 pages are in this category, out of 13 total. ... Core recovery parameters; G. Geological Strength Index; M. Mining rock mass rating; N.
Input Chart for determining RMR parameter intact rock strength Input Chart for determining RMR combined parameters RQD and discontinuity spacing. The details for calculating RMR are given by Edumine [4] and provide a series of tables for RMR determination while the latest charts for the same purpose are given in the references and further reading.
Nowadays the classification system itself is not very often used, but the determination of the RQD as index for rock core quality is standard practice in any geotechnical rock drilling, and is used in many, more recent, rock mass classification systems, such as RMR and Q-system (see above). Rock Structure Rating (RSR)
The parameters to calculate the RMR value are similar to those used in the RMR system of Bieniawski. This may be confusing, as some of the parameters in the MRMR system are modified, such as the condition parameter that includes groundwater presence and pressure in the MRMR system whereas groundwater is a separate parameter in the RMR system of ...
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construction parameters: size of tunnel; direction of drive; method of excavation. The RSR value of any tunnel section is obtained by summing the weighted numerical values determined for each parameter. The RSR concept is a very useful method for selecting steel rib support for rock tunnels.
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