Finite Element Analysis of Cone Penetration in Soil for Prediction of Hardpan Location

Abstract

An accurate determination of soil hardpan location is important for maximum precision tillage performance. Cone penetrometers are often used to locate hardpans in soils. This determination in layered soils is more complex due to the complexity of soil reaction to cone penetration. An axisymmetric finite element (FE) model was developed to simulate cone penetration for the prediction of the hardpan location in a layered Norfolk sandy loam soil. The soil was considered as a non-linear elastic-plastic material, and it was modeled using a Drucker-Prager model with the Hardening option in ABAQUS, a commercially available FE package. ABAQUS/Explicit was used to simulate soil-cone contact pair interaction. The results showed that the FE model captured the penetration resistance trend with two deflection points indicating the start of the hardpan and the peak cone penetration resistance. The FE-predicted results showed the hardpan at a depth of 7.29 cm compared to 11.08 cm from cone penetration tests. Soil moisture, bulk density, and cone surface conditions significantly affected the predicted and experimental results. The simulation also showed soil deformation zones about 3 times the diameter of the cone that developed around the advancing cone.