Based on the heterogeneity of rock, by using the RFPA2D, influene of the horizontal in-situ stresses on the distributions of plastic zones is discussed. Among the current problems that rock or civil engineers face, perhaps there is none as challenging as the characterization of fluid flow though fracturing rocks, especially when they are highly stressed. In mining and civil engineering projects, the re-distribution of the stress field during the excavation of tunnels and underground chambers lead to the formation of new fractures. These damages may cause dramatic changes in the permeability of the rock masses. As a result, the rate of water flowing into the tunnels and chambers will increase.