ABSTRACT
Comprehensive characterization of the geological, geotechnical, and hydrogeological conditions along the entire tunnel alignment or corridor is a fundamental requirement for the design of a rock tunnel. A comprehensive geological plan map should be prepared and present all relevant geological information at an appropriate scale. Key reference locations including the proposed tunnel alignment should be presented on the geological plan map. Rock mass fractures have a strong influence of excavation stability for rock tunnels. Each identified family of rock mass fractures should be thoroughly described using appropriate geological terms including the presence of smooth surfaces and slickensides, weak infilling, and weak wall rock. The deterioration potential or non-durability of any type of rock to be encountered along a tunnel alignment should be thoroughly evaluated and quantified and presented in terms of the severity of deterioration and swelling potential. The groundwater conditions prevailing along a tunnel alignment play an important role in both the design and construction of rock tunnels.
