Finite element modeling and Simulations to investigate the relationship between the cone index profile and draft requirements of a compaction profile sensor with depth

Andrade-Sanchez et al. (2007, 2008) tested a compaction profile sensor and a standard cone penetrometer over a wide range of soil types and conditions and found that the unit pressure acting on the cutting edge, defined as the cone index equivalent (CIE) at a specific depth (d) was related to the cone index (CI) value at that depth, the depth of the cutting edge (d) and the interaction between CI and depth of the cutting edge (i.e., CI∗d) with a very high coefficient of multiple determination irrespective of the soil types and conditions. The objective of this study was to provide an analytical explanation for this finding. Two-dimensional axisymmetric model for soil-cone interaction and three-dimensional model for soil-tine interaction were developed using a Finite Element Method (FEM). A non-linear elasto-plastic constitutive behavior along with the Drucker-Prager yield criterion was used to represent soil cutting process. Simulations studies were conducted in 25 distinct soil types and conditions and the results indicated a similar relationship between CIE and CI as observed by Andrade-Sanchez et al (2007, 2008). These results support the existence of strong theoretical basis to the empirical relationship observed by Andrade-Sanchez et al (2007, 2008).