Rock mass usually refers to natural geological rock mass within a certain engineering range which undergoes various geological processes and retains permanent deformation and geological structure traces under the long-term effect of ground stress.[1] In a narrow sense, rock mass is composed of rocks (rock blocks) and discontinuous/structural planes. The structure plays a major role in controlling the mechanics and deformation characteristics of rock mass. Therefore, the properties of the structural plane must be considered in the engineering classification of rock mass.