Excavation Rock Mass Rating (ERMR) system is developed on the basis of numerous investigations for different civil engineering and mining projects in R. Macedonia. In this system, all Rock Masses are divided in seven classes. For each class, an adequate technology of excavation is suggested. Beside other analyses, the correlation of ERMR with known rock mass systems is given in order to have data for parallel use in solving of different practical problems. Notes about possible practical application of the system are analyzed and results presented in short. It can be underlined, that the ERMR system is more adequate for assessment of type of excavation technology for soft and hard rock, while for coarse grained sedimentary rocks, somewhat modified classification can be used.

1 Introduction

One of the main problems in rock engineering is to predict ease of excavation of rock masses in an appropriate manner. This is very significant in earthworks for civil engineering works and in surface mines because of the quantity of excavation masses. In fact, this is one of the key problems in organization and technology of excavation, prediction of costs and safety aspects.

Several authors give effort to establish acceptable methodologies for practical use in this important scientific and practical field, as: Franklin et al. (1971), Weaver (1975), Kirsten (1982), Abdullatif & Cruden (1983), Pettifer & Fookes (1994), Singh et al. (1987), Jovanovski (2001), Tsiambaos & Saroglou (2010).

In general, in all classifications, main parameters for assessment of excavatability are uniaxial compressive strength, weathering degree, spacing of discontinuities, hardness, seismic velocity, continuity, aperture, orientation and roughness of joints etc. Anyhow, no particular method is universally accepted because of the complex nature of the rock masses and difficulties in determination of the input parameters.

Having this in mind, a classification system called ERMR (Excavation Rock Mass Rating) is presented.

The classification is developed on the bases of numerous investigations for different structures, with a main idea to have possibility to determine easy of excavation for non-coherent and coherent soils, weak and hard rock masses in one method (Jovanovski 2001).

Beside the analyses, several correlations of ERMR with known rock mass systems are given in order to have basis for parallel usage of the system for different practical problems.

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