ABSTRACT
However, the rock, in essence, is a kind of heterogeneous material contains defects such as lots of micro-crack, as well as some inclusions. Propagation of defect stress concentration and crack development plays an important role in the process of deformation and failure of surrounding rock, especially the process of splitting and unloading crack. Based on this understanding, fracture mechanics, damage mechanics, and statistical mechanics method have got a booming developed. These micro mechanical methods make assumptions for the size, shape and angle of micro-crack, which is helpful in the research of the distribution and propagation of stress around the single crack periphery.
