Abstract: This work attempts to establish a mechanical model to compute the non linear mechanical behaviours of the granular geomaterials in cohesive contact on micro level by means of the numerical methods. The technique of analysis on the micro level, particularly to consider the cohesive property on the contact surface is given. The non linear mechanical behaviours with different coefficients of frictional are presented and the shear resistance are studied for the different micro structures. The works presented in this paper is a fundamental study for the analysis of the related problems.