This paper presents the results of performance analysis on the support systems recommended by the RMR (rock mass rating) rock mass classification system. Rock-support interaction is analyzed by means of both numerical and multiple regression modeling. Five different rock mass conditions were assumed from very poor to very good, each representing varied RMR. Extensive computer simulations were conducted to investigate the stresses, displacements, and yielded zones around a circular opening excavated at different depths, and under different rock conditions. The performances of the RMR recommended support systems were analyzed and the stability of excavation was evaluated. Multiple regression modeling was conducted to assess the relationship between support pressure, depth, and tunnel deformation for different rock conditions. Regression models were derived and the response surfaces were constructed, showing the interaction between tunnel depth, support pressure, and tunnel displacement. Using the derived models and the constructed response surfaces, engineers are able to describe the support performance and assess the practical range of expected deformation for their specific site conditions. Also, the approach presented can be used for any special case.