The rock mass deformation modulus is an important input parameter in deformation analysis of rock mass. The quantity of this parameter is affected by intact rock strength and rock mass environment that is considered in this paper by sensitivity analysis of rock mass classification related empirical equations. Results show that the influence of rock mass environment on rock mass modulus is more than intact rock strength especially in RMR and GSI classification systems. Whereas, difference of intact rock strength and rock mass environment effect is low in Q and RMi systems.
The rock mass deformation modulus is an important input parameter in any analysis of rock structures and structures in or on rock. Although field tests are better methods to determine this parameter, but they are so time consuming and imply notable costs and operational difficulties. The rock mass modulus is affected by intact rock strength (σci) and rock mass condition: joint sets number, spacing and surface condition that in this paper is called rock mass environment (RME). The rock mass classification systems assess the rock mass behavior based on σci and RME, so effects of these parameters are considered in related equation inherently. Since in each classification scheme, effects of σci and RME are taken into account differently, therefore investigating of these parameters influence on related empirical equations results can provide a better understanding in rock mass deformability concept.
In this paper the influence of σci and RME on rock mass modulus is being considered by sensitivity analysis of estimated deformation modulus in empirical equations to σci and RME (as input parameters). In this respect, a variation range is selected for each input parameter. @Risk software is used to find the influence of effective parameters.