One of the most important parameters required in the design of major structures and other facilities on rock is the modulus of the rock mass.
In evaluating the stress/strain behavior of rock, the rock mass modulus is not only the most important parameter, it is also the most difficult to determine. Modulus measurements are performed, in situ and in the laboratory, both statically and dynamically. The results rarely agree.
In this paper, a literature search of current practices in modulus determination for rock mechanics problems is performed.
Various available methods in determining this parameter are critically examined.
Factors affecting the determination of rock mass modulus are discussed from a theoretical standpoint and from the author's practical experience with major power plant foundations.
Recommendations regarding methods of determining rock mass modulus for various rock mechanics problems are provided.
The results of the work incorporate considerations of geology, statics, dynamics, and laboratory and field measurements and engineering.