Rock mass characterization for an underground excavation support system: The Sabzkuh water conveyance tunnel, Iran

Abstract

There are various structural and geological stratigraphies in study area. The main lithology includes the shale, marl, limestone and dolomite that belong to the Cambrian to upper Cretaceous besides Quaternary deposits. To identify the engineering and geotechnical characteristics of the rock mass along the tunnel route, the results of laboratory and in situ tests, geophysical explorations (geoelectrical methods), field observations and borehole logging charts have been used. The well-known rock mass classification systems for tunnelling purposes (RMR, GSI and Q-system) have been used. Using the GSI classification system for rock mass, the modified Hock- Brown criterion parameters of the rock mass for typical section were determined. The RMR was used to determine the required support for the entire length of tunnel. Also the Q system was used to compare the required support from Q system with the RMR system. Finally rock-support interaction analysis was conducted for a typical cross section of the tunnel. Using the above empirical and analytical methods, the required supports were compared for a typical section. © 2004 Elsevier Ltd.