Rock mass consists of intact rock and discontinuity features which are formed a lot of blocks. Discrete Fracture Networks (DFN) makes a more closely geometrical model to the reality and Discrete Element Method (DEM) is a strong numerical tool for simulating the former complex media. Using DEM modeling the deformability of the rock mass and also individual blocks within the model are calculated. Such displacements may cause unbalance subsidence in dam foundations and therefore it has a great influence on stability of dams. Existence of water flow through the fractures may also increase the instability of dam foundation mainly due to the effect of pore pressure. Dynamic loading from different sources such as earthquake is also oscillated blocks, which is an important factor in the structural instability. In the previous research work in this field of study, they did not performed a systematic numerical modeling to take into account all aforementioned phenomena on dam foundation using a hybrid DFN-DEM approach which is the main objective of this research work. The basic geometrical and mechanical parameters for numerical modeling were taken from Rudbar-Lorestan dam site. To avoid of random effect, a large number of stochastic DFN model was generated and the rate of foundation subsidence under different loading conditions are calculated. Dynamic analysis was performed based on the history of a Design Basis Earthquake. The results show a great degree of uncertainty between the calculated subsidence values from equivalent continuous and discontinuous media. The calculated subsidence value in different part of foundation is different. The maximum estimated subsidence was 10cm in dry condition. During the dynamic loading the rock blocks were experienced vibration and they were move up to 5cm from their original locations which may have a harmful impact in dam body.
