ABSTRACT
In civil engineering, rocks refer to geological materials that cannot be crushed by hand squeezing or be partially scrunched. In geology, rocks pertain to lithified solid materials of igneous, sedimentary, pyroclastic or metamorphic origin.[1] The physical properties of rocks include porosity, density, water absorption and hydraulic properties. Among them, rock porosity exerts important influence on the mechanical properties of rocks. Void spaces in rocks include pores and micro-fissures. Pores affect water flow in rocks. Conversely, the micro-fissures affect the distribution of the deformation and internal stress of rocks. The properties of micro-fissures are as important as the minerals in the rock itself. Micro-fissures can reduce rock strength. Whether the micro-fissures close or not can lead to discrete differences in the rock test results. Griffith’s strength theory explains the effects of micro-fissures on tensile strength and the brittle failure of rocks. Commonly used rock failure theories include Mohr strength theory, which mainly deals with the stress analysis of rock shear failure.
