A study on mechanical characteristics of the unloading rock mass

The natural mechanic condition of the rock mass is discussed. According to the unloading test of the rock mass, a study is done on the relationship between stress and strain and its characteristics. In different stages of unloading, the result shows that the relation of unloading rock mass between stress and strain is nonlinear, and the deformation modulus changes gradually. Based on the size effect study on unloading rock mass, the data displays that the deformation modulus and tense strength is sensitive to the size of sample in test. All this discovery is useful and meaningful for engineering application, which reveals the unloading rock mass is different from the traditional loading rock mass theory, more attention is asked for the research of unloading rock mass in engineering practice.