The design and construction of long and deep tunnels, particularly those at great depths, is generally associated with a high level of risks due to a series of uncertainties involved, and the success of such tunneling projects depends on the correct identification of associated geo-mechanical hazards and excavation behavior and proper choice of the supports section. The situation is more criticalfor tunneling in Himalayan regions which are relatively weaker formations. Active and continuous movement of Hinalayan ranges creates slope instability phenomena thereby changing the landscape and posing challenges to conventional tunnel designs and constructions. Hence, a robust approach needs to be adopted for determining the optimal support system (or combination of systems) forexcavationof tunnels, based on the principles of risk analysis and multi-criteria analysis. The current paper presents Geodata's approach for determining geomechanical hazards and adopting relevant tunnel support system. In particular, the scheme proposed is essentially based on the combination of two classification systems: the first is basically centered on the results of stress analysis, while the second, which is made up of the RMR system, is specifically directed towards the representation of the geo-structural characteristics of the rock mass and to the relative self-supporting capacity.
