The Applicability of Rock Bolt Supporting Factor based on Rock Mass Behavior: A Case Study of Alborz Tunnel

A better understanding of rock mass behavior is an essential part of the design and construction of underground structures. Any improvement in the understanding of the behavior of rock mass will facilitate the improvement of the design in terms of the safety of the working environment, long-term safety of the structure, environmental effects, and sound management of public or private resources. Thus, in step one in this paper the experience gained from applying the GDE (Geo Data Engineering) multiple graph approach for rock mass classification and assessing its behavior throughout excavation of the Alborz tunnel is presented. The predicted hazards are compared with the experienced problems and suggestions are given to be considered in future works of tunnel construction. In step two, the GDE multiple graph approach is compared to the rock mass behavior types proposed by Palmstrom & Stille (2007) in terms of the continuity of rock mass. The result of this comparison together with the data obtained from rock mass classification in the Alborz tunnel are used to develop a system that determines the applicability of the rock bolt supporting factor (RSF) in different rock mass behavior classes.