In this paper, the application of the disturbed state concept model for the assessment of liquefaction potential is examined through experimental and analytical investigation. In order to achieve a more realistic description of the dynamic responses of saturated sands, the disturbed state concept model was modified based on the dynamic effective stress path and excess pore pressure development. Static and cyclic undrained triaxial tests were performed for sands with different relative densities and confining stresses. Based on test results, a classification of liquefaction phases was proposed, in terms of the dynamic effective stress path and the excess pore pressure development. This was adopted into the modified disturbed state concept model. The liquefaction assessment method is also proposed, using the disturbed state concept model based on the deviatoric plastic strain trajectory. Factors of safety, calculated from the equivalent cyclic stress concept, were compared with the proposed method using the original and modified disturbed state concept models. This was proposed by using examples with different soil and earthquake conditions.