A numerical study of the penetration test at constant rod velocity

Penetration tests are widely used in geotechnical engineering for the on site characterization of mechanical properties of soils. This paper proposes a numerical study of static penetration tests on granular material using Discrete Element Method and in particular molecular dynamics in 2 dimensions (Cundall and Strack, 1979). The results first showed the ability of the model to reproduce qualitatively the results of penetration tests classically obtained in experimental conditions. Then, the energy balance of the test is analyzed at the macroscopic and microscopic to understand local parameters influencing this test and how to interpret this test. The most part of the source energy is irreversibly lost and dissipated by friction in the contacts between particles; the remaining part of energy is stored by the upper confining wall. The sample area mobilized by frictional dissipation remains approximately the same as penetration velocity increases but the dissipated energy level increases for particles in this area.