PENNSYLVANIA STATE UNIV UNIVERSITY PARK DEPT OF MINERAL ENGINEERING
This report discusses tunnel design procedures based on various rock mass classification systems. A comparison is made between the tunnel support design based on the classical Terzaghi rock load method and the support selection based on the RSR Concept, the Geomechanics Classification, and the Q-System. These classification systems are described in detail and guidelines are given for step-by-step application of the three methods. Using an actual tunnel case history, an evaluation is made of the current design practice by comparing it with the design approaches involving the three rock mass classification systems. It is concluded that the current design practice may lead to overdesign of support, and recommendations are made for improved procedures that would ensure the construction of safe and more economical rock tunnels. Finally, a few areas are identified where more research would benefit the current tunnel design practice.