Abstract: Using model tests and numerical simulation by PFC2D,the mobilization mechanism of toe resistance of piles in sand was studied.The variations of soil displacement,soil stress and void ratio around pile toe with the increase of toe resistance were observed in the model tests.At the same local displacement,compared with that in loose sand,larger toe resistance would be mobilized in dense sand because the influenced soil zones around the pile toe were larger.At the starting of the mobilization of toe resistance,the displacements of the soils around pile toe were vertical and inclined expansion downward.However,the displacements of the soils around pile toe turned to be horizontal and inclined expansion upward in the limit state of toe resistance.It was shown by the soil displacement,the stress field,and the variations of void ratios in the soils around the pile toe that the mobilization of toe resistance was accompanied with the sphere shape expansion of the soils around the pile toe.In the numerical simulation using PFC2D,the pile and sands were simulated by walls and particles,respectively.The results of numerical simulation were well consistent with those of the model tests.