JH classification method is confirmed by the database of up to 6,101 sections of tunnels constructed by Japan Highway Public Corporation. The method can figure out either strength or deformability of rock mass, further appropriating the amount of rock bolts, thickness of shotcrete and size of pitch of steel ribs just after the blasting procedure. Based on these advantages of JH method, in this study, according to data of five deep and long tunnels in Iran, two equations for estimation of value of JH method from Q and RMR classification systems were developed. These equations were able to optimize the support system for Q and RMR classification systems. From data processing, it is pointed out that the JH method for the design of support system in underground working is more reliable than the Q and RMR classification systems.
The most important points in the design of support systems for underground structures can be referred to initial studies to determine the type of rock and the rock mass. Various methods have been proposed for designing and analyzing in underground spaces. The use of these methods requires knowledge of their limitations. Bieniawski (1984) also holds that the quality of input data for design with design requirement is necessary. Experimental methods always have fewer limitations and need tests to that are not costly in the projects. Several methods for the classification of rock masses for the design of support system are presented which include: Barton (1974) Hoek & Brown (1980) and Bieniawski (1984)..
All data used was collected from five tunnels including Golab, Behesht Abad, DashteZahab, Alborz and Sabzkooh Tunnels in Iran. General specifications of tunnels and geological properties of rock mass can be seen in Table 1. Geomechanical properties of rock masses are shown in Table 2.
