The cyclic mobility model proposed in this paper is of a generalized plasticity-multiple mechanism type. The salient feature of the present approach is that the
concept of the multiple mechanism, within the framework of plasticity theory defined in strain space, is used as a vehicle for decomposing the complex mechanism
into a set of one dimensional mechanisms. This makes it possible to obtain not only incremental but also integrated constitutive relations. The undrained stress path is idealized with the concept of liquefaction front, which is defined in the effective stress space as an envelope of stress points gradually approaching failure line.
　Once coded into the finite element program, most of the existing models suffer from serious difficulty in the numerical solution process when effective stress path becomes very close to the failure line.
　A numerically robust approach is proposed in this paper by introducing a scheme for gradually enlarging scale of shear strain with the progress of cyclic mobility.