The stabilization of underground spaces is one of the most challenging topics in engineering geology. There are several methods to determine the type of tunnel stabilization system, but most of these methods have several weaknesses. Therefore, the development of a method that comprehensively considers almost all parameters influencing tunnel stability and their interdependencies has not received sufficient attention. The aim of this research is to investigate the parameters influencing the stability of tunnels using the rock mechanics system method. In this paper, 6 tunnels with different geological characteristics were selected. The effective parameters on the primary stabilization of these tunnels were coded using the ESQ method. Subsequent analyses were performed using the RES rock engineering system method to estimate and evaluate the optimal tunnel stabilization system. The results showed that parameters such as weathering of the joint surface, backfill and joint spacing played a more effective role than other parameters. For comparison, the analyses were also carried out using the RMR rock mass ranking method. The comparison between the results of the RES and RMR methods showed that the results of the RES method are in better agreement with the actual tunnel conditions and the shotcrete thickness of the proposed stabilization system of the studied tunnels. Since there is no limit to the number of input parameters in this method and, on the other hand, the mutual influence of the parameters on each other is considered, the relationships obtained from the RES method in this research can be effectively used in engineering projects along with other methods.
