Engineering geological investigations along the Meram railway tunnel, Konya, Turkey

Abstract

This paper presents the results of the geological and geotechnical studies of the rock masses along the Meram railway tunnel. The study area consists of limestone which is the base rock and covers a large area between the entrance and exit portals and sandstone which is only observed at the slope of the hill that overlies the tunnel. Results obtained from rock mechanics testing indicate that the limestone along the tunnel route is a moderately strong rock with an average uniaxial compressive strength of 61.88 MPa. Rock mass qualities of the rock units along the tunnel were determined by means of rock mass rating (RMR), Geomechanics Classification (Q) system and New Australian Tunneling Method (NATM). The study shows a very poor-to-fair rock mass conditions, with a rock mass rating (RMR) ranging from 40 to 49 and rock mass quality (Q-system) ranges between 0.69 and 2.52. The limestone was classified according to NATM into two ground categories, which are B2 (friable) and B3 (very friable). Correlations with the RMR, Q-systems and NATM suggested rock bolts and shotcrete as a suitable preliminary support system for the rock mass during excavation.