Numerical study of AE and DRA methods in sandstone and granite in orthogonal loading directions

The directional dependency of the acoustic emission (AE) and deformation rate analysis (DRA) methods was analyzed, based on the contact bond model in the two-dimensional particle flow code (PFC2D) in two types of rocks, the coarse-grained sandstone and Aue granite. Each type of rocks had two shapes, the Brazilian disk and a square shape. The mechanical behaviors of the numerical model had already been verified to be in agreement with those of the physical specimens in previous research. Three loading protocols with different loading cycles in two orthogonal directions were specially designed in the numerical tests. The results show that no memory effect is observed in the second loading in the orthogonal direction. However, both the cumulative crack number of the second loading and the differential strain value at the inflection point are influenced by the first loading in the orthogonal direction.