Physical modeling and arbitrary Lagrangian–Eulerian finite element analysis of indentation of a sensitive clay by a flat-ended axisymmetrical indenter

Abstract

Abstract Because indentation tests which are used in several engineering fields allow obtaining material strength parameters in a fast, reliable and reproducible manner, the present study was initiated with the aim of finding out whether such tests could also be used in geotechnical engineering. Experimental results are obtained from undrained indentation tests performed with a rigid flat-tipped, cylindrical indenter on Champlain clay specimens in order to deduce values of elastic moduli and yield stresses. These values are compared to those deduced from unconfined compression tests. Results of an Arbitrary Lagrangian–Eulerian (ALE) based finite element analysis that simulates such test are also presented. It is assumed that the clay behaves as a linear-elastic, perfectly plastic material obeying von-Mises yield criterion. A frictionless contact interface is chosen to realistically model interactions on the indenter-clay, clay-platen and clay-ring interfaces. The paper presents distributions of contact pressures beneath the indenter and along lateral and lower boundaries. Typical contours of von Mises deviator stress and equivalent plastic strain corresponding to different indentation depths in the clay specimen are presented. It is also shown that the presence of hairline cracks on the clay along the perimeter of the indenter and the limited thickness of the sample affect the deduced values of Young’s modulus and yield stress.

Keywords

• Flat-ended cylindrical indentation tests
• Sensitive clay
• FEM modelling
• Abaqus explicit
• Young’s modulus and yield stress
• Comparisons