Numerical Parametric Study of Piezocone Penetration in Anisotropically Consolidated Clay

 

Lei Wei

Geotechnical Engineer, Hillis-Carnes Engineering Associates, Inc., Waldorf, MD, USA
e-mail: lwei2@lsu.edu

Murad Abu-Farsakh

Research Assistant Professor, Louisiana Transportation Research Center, Louisiana State University, Baton Rouge, LA, USA
e-mail: mabuf@ltrc.lsu.edu

and

Mehmet T. Tumay

Georgia Gulf Distinguished Professor, Associate Dean for Research & Graduate Studies, College of Engineeringg, Louisiana State University, Baton Rouge, LA, USA
e-mail: mtumay@eng.lsu.edu

ABSTRACT

A finite element analysis is performed to analyze the effect of soil anisotropy on the piezocone penetration test (PCPT) in normally consolidated clay. The piezocone penetration is numerically simulated based on a large strain formulation using the commercial finite element code ABAQUS. The Anisotropic Modified Cam Clay Model (AMCCM) by Dafalias (1987) was chosen and implemented into ABAQUS through the user subroutine UMAT. For verification purposes, numerical simulations were first performed on previously conducted calibration chamber PCPT tests, and the predicted results were compared with the measured values. For different initial stress conditions, the tip resistance, sleeve friction and excess pore pressure profiles are provided. To show the effect of soil anisotropy, the predicted results from using AMCCM and MCCM (Modified Cam Clay Model) models were compared. The results show that the AMCCM gives better predictions than the MCCM. Finally, non-uniform normal and frictional stress distributions were found along both the cone tip and the shaft surface.

KEYWORDS: finite element; piezocone penetration; initial stress anisotropy

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