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Geomechanics and Engineering Volume 8, Number 4, April 2015 , pages 559-594 DOI: https://doi.org/10.12989/gae.2015.8.4.559 |
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Analyzing consolidation data to obtain elastic viscoplastic parameters of clay |
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Thu M. Le, Behzad Fatahi, Mahdi Disfani and Hadi Khabbaz
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| Abstract | ||
| A nonlinear creep function incorporated into the elastic visco-plastic model may describe the long-term soil deformation more accurately. However, by applying the conventional procedure, there are challenges to determine the model parameters due to limitation of suitable data points. This paper presents a numerical solution to obtain several parameters simultaneously for a nonlinear elastic visco-plastic (EVP) model using the available consolidation data. The finite difference scheme using the Crank-Nicolson procedure is applied to solve a set of coupled partial differential equations of the time dependent strain and pore water pressure dissipation. The model parameters are determined by applying the algorithm of trust-region reflective optimisation in conjunction with the finite difference solution. The proposed method utilises all available consolidation data during dissipation of the excess pore water pressure to determine the required model parameters. Moreover, the reference time in the elastic visco-plastic model can readily be adopted as a unit of time; denoting creep is included in the numerical predictions explicitly from the very first time steps. In this paper, the settlement predictions of thick soft clay layers are presented and discussed to evaluate and compare the accuracy and reliability of the proposed method against the graphical procedure to obtain the model parameters. In addition, comparison of the available experimental results to the numerical predictions confirms the accuracy of the numerical procedure. | ||
| Key Words | ||
| elastic viscoplastic, finite difference solution, creep, soft soils | ||
| Address | ||
| (1) Thu M. Le, Behzad Fatahi, Hadi Khabbaz: Centre for Built Infrastructure Research, School of Civil and Environmental Engineering, University of Technology Sydney (UTS), Sydney, 15 Broadway, Ultimo NSW 2007 Australia; (2) Mahdi Disfani: Melbourne School of Engineering, The University of Melbourne, Parkville, VIC, 3010, Australia. | ||