Abstract
The effect of strain softening in geotechnical design of fills in areas with soft sensitive clays is studied by a large number of finite element analyses. The reduction in undrained shear strength with increasing shear strain after the peak value will reduce the maximum fill height before failure compared with a perfectly plastic material. The finite element program Plaxis together with the material model NGI-ADPSoft are used in this study. A non-local strain formulation is used in NGI-ADPSoft to overcome the crucial problem of mesh dependent results typical for this type of problems. The effect of brittleness is then fully controlled by input parameters. The material properties are taken from NGI’s database of undrained shear test results on high quality block samples. The effect of strain-softening is quantified by establishing a scaling factor Fsoftening that gives the ratio between the calculated capacity without and with the effect of softening. The purpose is then that the peak undrained shear strength of sensitive clays simply can be divided by this factor before used in conventional limit equilibrium analyses with a strain independent (perfectly plastic) assumption to indirectly account for the effect of brittleness.
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Acknowledgments
The authors would like to thank the Norwegian Public Road Administration and the Norwegian Water Resources and Energy Directorate that partly have funded this research work. A special thank is also given to Dr. Grimstad at Oslo and Akershus University College of Applied Sciences who has developed the automated calculation procedure in Plaxis which was essential for performing this large parametric study. Finally, the authors wish to acknowledge Prof. Steinar Nordal at NTNU and Prof. Minna Karstunen at Chalmers University of Technology for the review and constructive feedback on this paper.
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Jostad, H.P., Fornes, P., Thakur, V. (2014). Effect of Strain-Softening in Design of Fills on Gently Inclined Areas with Soft Sensitive Clays. In: L'Heureux, JS., Locat, A., Leroueil, S., Demers, D., Locat, J. (eds) Landslides in Sensitive Clays. Advances in Natural and Technological Hazards Research, vol 36. Springer, Dordrecht. https://doi.org/10.1007/978-94-007-7079-9_24
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DOI: https://doi.org/10.1007/978-94-007-7079-9_24
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