Qomroud long tunnel project in iran: Rock mass characterization along the first 10.4 km

The arid Central Iran region suffers from water shortages and a limited water supply. Supplying sufficient water to this region has been a great challenge for the Iranian water supply industry in the last few decades. To satisfy these needs, one project will convey water from the adjacent Dez Highlands to a central Iran watershed known as Qomroud; it involves four tunnels and the longest section of this project is known as the Qomroud Long Tunnel (QLT) with a length of 36 km. This article describes rock mass lithomechanical characterization along nearly 10.4 km of the QLT based on extensive engineering geology and rock mechanics studies, including surface geology, joint-fabric study, borehole drilling and logging, and field and laboratory geotechnical testing. On-site rock mass characterization was based on classification systems such as rock mass rating (RMR), Qtunneling index, rock quality designation (RQD), geological strength index (GSI) and rock mass index (RMi). For defined geomechanical units, ph sical and mechanical properties were determined using ASTM standards and ISRM suggested methods. Results obtained from different rock mass classification systems for various rock units in different sections along the tunnel are presented, compared and interpreted in this article.