Engineers generally employ empirical methods to estimate the properties of rock mass for the stability assessment of structures and feasibility studies since in-situ tests are usually expensive to perform. For such purposes, rock mass classification systems such as RMR and Q system are often used. The authors have been concerned with the relations among rock mass classes and their physical and mechanical properties for some time and they gathered in-situ and laboratory test data from the sites in Japan as well as those at other parts of the world. These data are compiled and processed through an integrated data-base. The authors studied the relations between RMR value and the rock mass properties such as unit weight, deformation modulus, uniaxial compressive strength, friction angle, elastic wave velocity. Several direct empirical relations between the properties and RMR value are established. In addition, some relations for the normalised properties of rock masses by those of intact rock as a function of RMR value are also established. The validity of these relations is tested against the actual data together with similar relations proposed by others.
Mechanical properties of rock masses are of great concern when engineers assess the stability of structures in rock masses. Therefore in-situ tests are required to obtain these properties. However, these experiments are both cumbersome and expensive. For this reason, they are not performed unless the structures are of great importance. The authors have been concerned with this aspect of rock masses and they have been gathering the results of in-situ and laboratory tests together with rock classifications of test sites (Aydan et al. 1997). Although many data come from the sites in Japan, the data from other parts of the world have been also gathered. These data are compiled and processed through an integrated data-base.
