Abstarct: The main objective of the present study in stability analysis and designing a suitable supporting system to provide an adequate stability for the formation tunnels during their construction period. To achieve these goals all geological and geomechanical data along the tunnels were collected to be used in engineering rock mass classification using RMR and Q systems. The results of both classification methods show that the quality of the rock mass is very weak in the CZ zone but those of the LM1 and LM2 zones are in normal. Further investigation on these three groups of rock mass by ground response diagrams illustrates that a relatively vast plastic zone is produced around parts of tunnel located in rocks of the CZ zone, while it is negligible for the LM1 and LM2 zones. Following these, a set of comprehensive two dimensional numerical analysis was performed using UDEC software and their results have been checked and compared with those acquired by empirical RMR and Q systems and by analyzing ground response diagrams. At the next stage using UNWEDGE package a joint survey was performed to check the probability of rock wedge forming and then they have been investigated for the demanded safety factor.