For some of granular materials with large cohesive force

such as strong bond soil or cementitious sand and gravel and so on

their macroscopic creep behavior is mainly dependent on the properties of particle contact under low stress conditions. This paper aims at proposing a two-dimensional isotropic creep property of granular materials through the granular micromechanical approach. To achieve this objective

firstly an appropriate rate-dependent force-displacement relationship is introduced to describe the discrete inter-granular properties of granular materials. Secondly

with help of the Laplace transform

the solution for overall behavior of granular materials in the framework of linearly elasticity can be directly used for the solution of the associated linearly viscoelastic problem in the Laplace space; and then

the main problem is to accurately produce the inverse Laplace transform in the time domain. Thirdly

by taking respectively Reuss static

and Voigt and general kinematic localization assumptions

we obtain analytically the corresponding overall creep behavior of granular materials. Further

the upper and lower bounds of overall creep property are established. Finally

the obtained results compared with the numerical simulation by PFC2D are provided to illustrate their validation.