Rock mass classification systems and the finite element numerical method were applied to design support systems for the proposed underground openings.
It covers the investigations on the initial in-situ stress distribution features, rock mechanical properties, engineering rock mass classifications by different methods, numerical modeling for stability and support analysis, proper measures for rock excavation and support.
Finally, the empirical methods based on RQD are used to determine the deformation modulus and unconfined compressive strength of rock masses at five different sites including 13 cases, and the results are compared with those obtained by other empirical methods based on rock mass classification indices such as rock mass rating (RMR), Q-system (Q) and geological strength index (GSI).
The RMR and GSI methods were utilized for rock mass classification.
Basic Quality (BQ) method is a basic national standard of rock mass classification suitable for different industries in geomechanics and geotechnical engineering in China.
The rock mass classification systems (RMR, Q, GSI, RSR, SRC and RMi), the convergence confinement method and a 2D finite element computer software, Phase2 were used for empirical and numerical method, respectively.
The rock mass classification of the tunnel grounds was performed by utilizing the RMR method, Q system, NATM and the Geological Strength Index (GSI) classification which was followed by performing a geotechnical investigation along the tunnel grounds in order to obtain the geotechnical parameters for the stability analyses of the portals and of the tunnel.
Since in many cases rock quality designation (RQD) is the only rock mass classification index available, this paper outlines the key aspects on determination of RQD and evaluates the empirical methods based on RQD for determining the deformation modulus and unconfined compressive strength of rock masses.
Indeed, our classification method separated freestanding TRiCs into two groups, and our statistical analyses show that the difference in mass within the cavity between the groups is significant.
The rock mass classification, assessment of tunnel stability and necessary support types were carried out with Q, RMR and RMi systems as empirical tunnel support design methods.
