The value of Poisson's ratio is a crucial parameter in rock mechanics and engineering
for both intact rock and rock mass. Poisson's ratio has not gotten the attention it
merits compared to other essential mechanical characteristics of intact rock and rock
mass. Limited relationships exist between rock mass classification systems (such as
RMR, RMQR, Q, and GSI) and Poisson's ratio. This paper provides a comprehensive review
of models proposed by various researchers for estimating Poisson's ratio for rock
mass. The different methods are compared, and new general equations are derived. The
results indicate that the Poisson's ratio value of rock mass is inversely proportional
to its quality and strength and depends on the Poisson's ratio value of the intact
rock. Specifically, a linear equation is obtained using the RMR or GSI system, showing
that the Poisson's ratio increases as the quality and strength of the rock mass decrease.
The Q system has a logarithmic link between the rock mass quality and Poisson's ratio.
It should be noted that the derived equations are applicable only under the assumption
of a homogeneous isotropic rock mass.