Role of Defects in Rock Mass Classification

Despite the advancement of the sophisticated numerical modelling techniques used to estimate rock mass strength, rock mass classification still remains as one of the key inputs and fundamental tools for rock mass characterization, especially in the early stages of project development. A challenge faced by practitioners who use rock mass classification schemes is the appropriate description and incorporation of rock mass defects—especially those outside the category known as “open joints”. This paper discusses the author’s experiences with various techniques used to describe and assess such defects.