Interpretation of cone penetration test in clay with smoothed particle finite element method

Cone penetration test (CPT) is widely used to explore the in situ soil mechanical properties and the stratigraphy. The numerical simulation of CPT can help understand its mechanical process and link the testing data to soil properties. However, this task is challenging due to multiple (i.e., geometric, material and contact) nonlinearity of the problem. This study extends a large deformation numerical framework, smoothed particle finite element method (SPFEM), to address this problem. A finite element formulation for multibody frictional contact problems is incorporated to deal with the interaction between the steel cone and soil. An explicit stress point integration scheme with substepping is adopted to solve the elastoplastic constitutive equation of soil. The details of the novel numerical procedure are demonstrated. Using the developed approach, parametric studies are conducted for both undrained Tresca soil and fully drained modified Cam-Clay. The correctness and robustness of the proposed approach are validated. For the undrained Tresca soil, a linear relationship between the cone factor Nkt\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$N_{kt}$$\end{document} and the natural logarithm of rigidity index ln(Ir)\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\mathrm {ln}(I_{r})$$\end{document} is confirmed, and then, a new equation for the interpretation of soil undrained shear strength is proposed. For fully drained modified Cam-Clay, the effects of some model parameters and earth pressure coefficient at-rest K0\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$K_0$$\end{document} on the drained cone factor are elucidated. Direct numerical simulation of CPT with SPFEM can provide an effective approach to determine some key parameters of the soil constitutive model and therefore improve the accuracy of numerical simulation for engineering applications.