Application of RMR and Q geomechanical classification systems along the proposed Mujib Tunnel route, central Jordan

Abstract

This paper highlights the engineering geological investigations that have been carried out along the proposed Mujib Tunnel. The geomechanical classifications – rock mass rating (RMR) and Q index for tunnelling purposes – have been used to categorize the rock mass along the proposed tunnel. This tunnel will be driven into the Cambrian Sandstones (Um Ishrin Sandstone Formation) which are characterized by two to three sets of structural discontinuities. The geotechnical information obtained from drilled boreholes as well as from surface discontinuity mapping using scanline techniques indicates fractured sandstone along the proposed tunnel. This would be classified as very poor to fair quality material using the Q indexand RMR values. An expert system was used to obtain the design parameters of the proposed tunnel and to determine the support requirements.