Abstract: To study macro and micro mechanical properties of cone penetration tests in structured sand, a pure sand ground was prepared firstly under 10 g condition. Then, a bond contact model considering bond thickness was implemented into the pure sand ground to prepare the structured sand ground. A penetrometer composed of four sides of rigid walls was moving downward to simulate cone penetration tests in structured sand ground. The results showed that with the increase of penetration depth, the tip resistance increased gradually but the growth rate slowed down step by step. When the tip reached the critical depth, the tip resistance began fluctuating around a certain value. The contact force chain around the tip is very concentrated. With the increasing penetration depth, the concentrative degree of contact force chain increased gradually and the concentration range of contact force chain expanded gradually. In the process of penetration, the soil around the penetrometer underwent a significant loading and unloading process, and the principal stress direction took rotation. The farther away from the penetrometer, the slower rotation speed of the principal stress, and the smaller the final rotation angle. The averaged pure rotation rate (APR) at different depths changed in a qualitatively identical way, but the APR maximum values increased gradually with the depth of soil. The cone penetration breaks the bond between the soil particles. There are two main kinds of bond failure modes, tension-shear breakage and compression-shear breakage, and the number of tensile-shear breakage is much more than that of compression-shear breakage.

Key words: cone penetration tests, structured sand, distinct element method, macro and micro mechanical properties