Abstract: Investigation of dam behavior during the construction and service phases is a very useful tool to control, to correct and to optimize the design process and to provide required contrivances during these phases. The aim is to prevent the probable damages and destructions and to maximize the commercial efficiency of the project. Because of mentioned reasons, installation of suitable instrumentations for analysis of effective parameters in performance and stability of dam during different periods is inevitable. In the present study, behavior of pore water pressure inside the foundation of Alavian dam (Iran) is studied. Plaxis is used to model the dam and the predicted results are compared with the measured ones. Then, the effect of foundation and cut-off wall permeability on the distribution of pore water pressure inside the foundation is investigated.